Acoustic cavitation-based monitoring of the reversibility and permeability of ultrasound-induced blood-brain barrier opening.

PubMed

Sun, Tao; Samiotaki, Gesthimani; Wang, Shutao; Acosta, Camilo; Chen, Cherry C; Konofagou, Elisa E

2015-12-07

Cavitation events seeded by microbubbles have been previously reported to be associated with MR- or fluorescent-contrast enhancement after focused ultrasound (FUS)-induced blood-brain barrier (BBB) opening. However, it is still unknown whether bubble activity can be correlated with the reversibility (the duration of opening and the likelihood of safe reinstatement) and the permeability of opened BBB, which is critical for the clinical translation of using passive cavitation detection to monitor, predict and control the opening. In this study, the dependence of acoustic cavitation on the BBB opening duration, permeability coefficient and histological damage occurrence were thus investigated. Transcranial pulsed FUS at 1.5 MHz in the presence of systemically circulating microbubbles was applied in the mouse hippocampi (n  =  60). The stable and inertial cavitation activities were monitored during sonication. Contrast-enhanced MRI was performed immediately after sonication and every 24 h up to 6 d thereafter, to assess BBB opening, brain tissue permeability and potential edema. Histological evaluations were used to assess the occurrence of neurovascular damages. It was found that stable cavitation was well correlated with: (1) the duration of the BBB opening (r(2)  =  0.77); (2) the permeability of the opened BBB (r(2)  =  0.82); (3) the likelihood of safe opening (P  <  0.05, safe opening compared to cases of damage; P  <  0.0001, no opening compared to safe opening). The inertial cavitation dose was correlated with the resulting BBB permeability (r(2)  =  0.72). Stable cavitation was found to be more reliable than inertial cavitation at assessing the BBB opening within the pressure range used in this study. This study demonstrates that the stable cavitation response during BBB opening holds promise for predicting and controlling the restoration and pharmacokinetics of FUS-opened BBB. The stable cavitation response therefore showed great promise in predicting the BBB opening duration, enabling thus control of opening according to the drug circulation time. In addition, avoiding adverse effects in the brain and assessing the pharmacokinetics of the compounds delivered can also be achieved by monitoring and controlling the stable cavitation emissions.

Focused Ultrasound-Induced Blood-Brain Barrier Opening: Association with Mechanical Index and Cavitation Index Analyzed by Dynamic Contrast-Enhanced Magnetic-Resonance Imaging

NASA Astrophysics Data System (ADS)

Chu, Po-Chun; Chai, Wen-Yen; Tsai, Chih-Hung; Kang, Shih-Tsung; Yeh, Chih-Kuang; Liu, Hao-Li

2016-09-01

Focused ultrasound (FUS) with microbubbles can temporally open the blood-brain barrier (BBB), and the cavitation activities of microbubbles play a key role in the BBB-opening process. Previous attempts used contrast-enhanced magnetic resonance imaging (CE-MRI) to correlate the mechanical index (MI) with the scale of BBB-opening, but MI only partially gauged acoustic activities, and CE-MRI did not fully explore correlations of pharmacodynamic/pharmacokinetic behaviors. Recently, the cavitation index (CI) has been derived to serve as an indicator of microbubble-ultrasound stable cavitation, and may also serve as a valid indicator to gauge the level of FUS-induced BBB opening. This study investigates the feasibility of gauging FUS-induced BBB opened level via the two indexes, MI and CI, through dynamic contrast-enhanced (DCE)-MRI analysis as well as passive cavitation detection (PCD) analysis. Pharmacodynamic/pharmacokinetic parameters derived from DCE-MRI were characterized to identify the scale of FUS-induced BBB opening. Our results demonstrated that DCE-MRI can successfully access pharmacodynamic/pharmacokinetic BBB-opened behavior, and was highly correlated both with MI and CI, implying the feasibility in using these two indices to gauge the scale of FUS-induced BBB opening. The proposed finding may facilitate the design toward using focused ultrasound as a safe and reliable noninvasive CNS drug delivery.

Focused Ultrasound-Induced Blood-Brain Barrier Opening: Association with Mechanical Index and Cavitation Index Analyzed by Dynamic Contrast-Enhanced Magnetic-Resonance Imaging.

PubMed

Chu, Po-Chun; Chai, Wen-Yen; Tsai, Chih-Hung; Kang, Shih-Tsung; Yeh, Chih-Kuang; Liu, Hao-Li

2016-09-15

Focused ultrasound (FUS) with microbubbles can temporally open the blood-brain barrier (BBB), and the cavitation activities of microbubbles play a key role in the BBB-opening process. Previous attempts used contrast-enhanced magnetic resonance imaging (CE-MRI) to correlate the mechanical index (MI) with the scale of BBB-opening, but MI only partially gauged acoustic activities, and CE-MRI did not fully explore correlations of pharmacodynamic/pharmacokinetic behaviors. Recently, the cavitation index (CI) has been derived to serve as an indicator of microbubble-ultrasound stable cavitation, and may also serve as a valid indicator to gauge the level of FUS-induced BBB opening. This study investigates the feasibility of gauging FUS-induced BBB opened level via the two indexes, MI and CI, through dynamic contrast-enhanced (DCE)-MRI analysis as well as passive cavitation detection (PCD) analysis. Pharmacodynamic/pharmacokinetic parameters derived from DCE-MRI were characterized to identify the scale of FUS-induced BBB opening. Our results demonstrated that DCE-MRI can successfully access pharmacodynamic/pharmacokinetic BBB-opened behavior, and was highly correlated both with MI and CI, implying the feasibility in using these two indices to gauge the scale of FUS-induced BBB opening. The proposed finding may facilitate the design toward using focused ultrasound as a safe and reliable noninvasive CNS drug delivery.

Apelin-13 Protects against Ischemic Blood-Brain Barrier Damage through the Effects of Aquaporin-4.

PubMed

Chu, Heling; Yang, Xiaobo; Huang, Chuyi; Gao, Zidan; Tang, Yuping; Dong, Qiang

2017-01-01

Apelin-13 has been found to have protective effects on many neurological diseases, including cerebral ischemia. However, whether Apelin-13 acts on blood-brain barrier (BBB) disruption following cerebral ischemia is largely unknown. Aquaporin-4 (AQP4) has a close link with BBB due to the high concentration in astrocyte foot processes and regulation of astrocytes function. Here, we aimed to test Apelin-13's effects on ischemic BBB injury and examine whether the effects were dependent on AQP4. We detected the expression of AQP4 induced by Apelin-13 injection at 1, 3, and 7 days after middle cerebral artery occlusion. Meanwhile, we examined the effects of Apelin-13 on neurological function, infarct volume, and BBB disruption owing to cerebral ischemia in wild type mice, and tested whether such effects were AQP4 dependent by using AQP4 knock-out mice. Furthermore, we assessed the possible signal transduction pathways activated by Apelin-13 to regulate AQP4 expression via astrocyte cultures. It was found that Apelin-13 highly increased AQP4 expression as well as reduced neurological scores and infarct volume. Importantly, Apelin-13 played a role of BBB protection in both types of mice by reducing BBB permeability, increased vascular endothelial growth factor, upregulated endothelial nitric oxide synthase, and downregulated inducible NOS. In morphology, we demonstrated Apelin-13 suppressed tight junction opening and endothelial cell swelling via electron microscopy detection. Meanwhile, Apelin-13 also alleviated apoptosis of astrocytes and promoted angiogenesis. Interestingly, effects of AQP4 on neurological function and infarct volume varied with time course, while AQP4 elicited protective effects on BBB at all time points. Statistical analysis of 2-way analysis of variance with replication indicated that AQP4 was required for these effects. In addition, Apelin-13 upregulated phosphorylation of extracellular signal-regulated kinase (ERK) and Akt as well as AQP4 protein in cultured astrocytes. The latter was inhibited by ERK and phosphatidylinositol 3'-kinase (PI3K) inhibitors. Our data suggest that Apelin-13 protects BBB from disruption after cerebral ischemia both morphologically and functionally, which is highly associated with the increased levels of AQP4, possibly through the activation of ERK and PI3K/Akt pathways. This study provides double targets to protection of ischemic BBB damage, which can present new insights to drugs development. © 2017 S. Karger AG, Basel.

Opening the Blood-Brain Barrier with MR Imaging-guided Focused Ultrasound: Preclinical Testing on a Trans-Human Skull Porcine Model.

PubMed

Huang, Yuexi; Alkins, Ryan; Schwartz, Michael L; Hynynen, Kullervo

2017-01-01

Purpose To develop and test a protocol in preparation for a clinical trial on opening the blood-brain barrier (BBB) with magnetic resonance (MR) imaging-guided focused ultrasound for the delivery of chemotherapy drugs to brain tumors. Materials and Methods The procedures were approved by the institutional animal care committee. A trans-human skull porcine model was designed for the preclinical testing. Wide craniotomies were applied in 11 pigs (weight, approximately 15 kg). A partial human skull was positioned over the animal's brain. A modified clinical MR imaging-guided focused ultrasound brain system was used with a 3.0-T MR unit. The ultrasound beam was steered during sonications over a 3 × 3 grid at 3-mm spacing. Acoustic power levels of 3-20 W were tested. Bolus injections of microbubbles at 4 μL/kg were tested for each sonication. Levels of BBB opening, hemorrhage, and cavitation signal were measured with MR imaging, histologic examination, and cavitation receivers, respectively. A cavitation safety algorithm was developed on the basis of logistic regression of the measurements and tested to minimize the risk of hemorrhage. Results BBB openings of approximately 1 cm 3 in volume were visualized with gadolinium-enhanced MR imaging after sonication at an acoustic power of approximately 5 W. Gross examination of histologic specimens helped confirm Evans blue (bound to macromolecule albumin) extravasation, and hematoxylin-eosin staining helped detect only scattered extravasation of red blood cells. In cases where cavitation signals were higher than thresholds, sonications were terminated immediately without causing hemorrhage. Conclusion With a trans-human skull porcine model, this study demonstrated BBB opening with a 230-kHz system in preparation for a clinical trial. © RSNA, 2016 Online supplemental material is available for this article.

Real-time monitoring of focused ultrasound blood-brain barrier opening via subharmonic acoustic emission detection: implementation of confocal dual-frequency piezoelectric transducers

NASA Astrophysics Data System (ADS)

Tsai, Chih-Hung; Zhang, Jia-Wei; Liao, Yi-Yi; Liu, Hao-Li

2016-04-01

Burst-tone focused ultrasound exposure in the presence of microbubbles has been demonstrated to be effective at inducing temporal and local opening of the blood-brain barrier (BBB), which promises significant clinical potential to deliver therapeutic molecules into the central nervous system (CNS). Traditional contrast-enhanced imaging confirmation after focused ultrasound (FUS) exposure serves as a post-operative indicator of the effectiveness of FUS-BBB opening, however, an indicator that can concurrently report the BBB status and BBB-opening effectiveness is required to provide effective feedback to implement this treatment clinically. In this study, we demonstrate the use of subharmonic acoustic emission detection with implementation on a confocal dual-frequency piezoelectric ceramic structure to perform real-time monitoring of FUS-BBB opening. A confocal dual-frequency (0.55 MHz/1.1 MHz) focused ultrasound transducer was designed. The 1.1 MHz spherically-curved ceramic was employed to deliver FUS exposure to induce BBB-opening, whereas the outer-ring 0.55 MHz ceramic was employed to detect the subharmonic acoustic emissions originating from the target position. In stage-1 experiments, we employed spectral analysis and performed an energy spectrum density (ESD) calculation. An optimized 0.55 MHz ESD level change was shown to effectively discriminate the occurrence of BBB-opening. Wideband acoustic emissions received from 0.55 MHz ceramics were also analyzed to evaluate its correlations with erythrocyte extravasations. In stage-2 real-time monitoring experiments, we applied the predetermined ESD change as a detection threshold in PC-controlled algorithm to predict the FUS exposure intra-operatively. In stage-1 experiment, we showed that subharmonic ESD presents distinguishable dynamics between intact BBB and opened BBB, and therefore a threshold ESD change level (5.5 dB) can be identified for BBB-opening prediction. Using this ESD change threshold detection as a surrogate to on/off control the FUS exposure in stage-2 experiments, we demonstrated both excellent sensitivity (92%) and specificity (92.3%) in discriminating BBB-opening occurrence can be obtained in animal treatments, while concurrently achieving a high positive predicted value (95.8%). Wideband ESD was also highly correlated with the occurrence and level of erythrocyte extravasations (r 2  =  0.81). The proposed system configuration and corresponding analysis based on subharmonic acoustic emissions has the potential to be implemented as a real-time feedback control structure for reliable indication of intact FUS-BBB opening for CNS brain drug delivery.

Real-time monitoring of focused ultrasound blood-brain barrier opening via subharmonic acoustic emission detection: implementation of confocal dual-frequency piezoelectric transducers.

PubMed

Tsai, Chih-Hung; Zhang, Jia-Wei; Liao, Yi-Yi; Liu, Hao-Li

2016-04-07

Burst-tone focused ultrasound exposure in the presence of microbubbles has been demonstrated to be effective at inducing temporal and local opening of the blood-brain barrier (BBB), which promises significant clinical potential to deliver therapeutic molecules into the central nervous system (CNS). Traditional contrast-enhanced imaging confirmation after focused ultrasound (FUS) exposure serves as a post-operative indicator of the effectiveness of FUS-BBB opening, however, an indicator that can concurrently report the BBB status and BBB-opening effectiveness is required to provide effective feedback to implement this treatment clinically. In this study, we demonstrate the use of subharmonic acoustic emission detection with implementation on a confocal dual-frequency piezoelectric ceramic structure to perform real-time monitoring of FUS-BBB opening. A confocal dual-frequency (0.55 MHz/1.1 MHz) focused ultrasound transducer was designed. The 1.1 MHz spherically-curved ceramic was employed to deliver FUS exposure to induce BBB-opening, whereas the outer-ring 0.55 MHz ceramic was employed to detect the subharmonic acoustic emissions originating from the target position. In stage-1 experiments, we employed spectral analysis and performed an energy spectrum density (ESD) calculation. An optimized 0.55 MHz ESD level change was shown to effectively discriminate the occurrence of BBB-opening. Wideband acoustic emissions received from 0.55 MHz ceramics were also analyzed to evaluate its correlations with erythrocyte extravasations. In stage-2 real-time monitoring experiments, we applied the predetermined ESD change as a detection threshold in PC-controlled algorithm to predict the FUS exposure intra-operatively. In stage-1 experiment, we showed that subharmonic ESD presents distinguishable dynamics between intact BBB and opened BBB, and therefore a threshold ESD change level (5.5 dB) can be identified for BBB-opening prediction. Using this ESD change threshold detection as a surrogate to on/off control the FUS exposure in stage-2 experiments, we demonstrated both excellent sensitivity (92%) and specificity (92.3%) in discriminating BBB-opening occurrence can be obtained in animal treatments, while concurrently achieving a high positive predicted value (95.8%). Wideband ESD was also highly correlated with the occurrence and level of erythrocyte extravasations (r (2)  =  0.81). The proposed system configuration and corresponding analysis based on subharmonic acoustic emissions has the potential to be implemented as a real-time feedback control structure for reliable indication of intact FUS-BBB opening for CNS brain drug delivery.

Opening of the blood-brain barrier with an unfocused ultrasound device in rabbits.

PubMed

Beccaria, Kevin; Canney, Michael; Goldwirt, Lauriane; Fernandez, Christine; Adam, Clovis; Piquet, Julie; Autret, Gwennhael; Clément, Olivier; Lafon, Cyril; Chapelon, Jean-Yves; Carpentier, Alexandre

2013-10-01

The blood-brain barrier (BBB) is a major impediment to the intracerebral diffusion of drugs used in the treatment of gliomas. Previous studies have demonstrated that pulsed focused ultrasound (US) in conjunction with a microbubble contrast agent can be used to open the BBB. To apply the US-induced opening of the BBB in clinical practice, the authors designed an innovative unfocused US device that can be implanted in the skull and used to transiently and repeatedly open the BBB during a standard chemotherapy protocol. The goal of this preliminary work was to study the opening of the BBB induced by the authors' small unfocused US transducer and to evaluate the effects of the sonications on brain parenchyma. Craniectomy was performed in 16 healthy New Zealand White rabbits; epidural application of a single-element planar ultrasonic transducer operating at 1 MHz was then used with a pulse-repetition frequency of 1 Hz, pulse lengths of 10-35 msec, in situ acoustic pressure levels of 0.3-0.8 MPa, and sonication for 60-120 seconds. SonoVue was intravenously injected during the US applications, and opening of the BBB was determined by detecting extravasation of Evans blue dye (EBD) in brain tissues, quantitative measurement of EBD with UV-visible spectrophotometry, and contrast enhancement after Gd injection in 4.7-T MRI. A histological study was performed to determine adverse effects. An opening of the BBB was observed over a large extent of the US beam in the brain corresponding to in situ pressures of greater than 0.2 MPa. The BBB opening observed was highly significant for both EBD (p < 0.01) and MRI Gd enhancement (p < 0.0001). The BBB opening was associated with minor adverse effects that included perivascular red blood cell extravasations that were less than 150 μm in size and not visible on MR images. Moderate edema was visible on FLAIR sequences and limited to the extent of the sonication field. The results demonstrate that the BBB can be opened in large areas of the brain in rabbits with low-power, pulsed, and unfocused US with limited damage to healthy tissue.

Molecules of various pharmacologically-relevant sizes can cross the ultrasound-induced blood-brain barrier opening in vivo

PubMed Central

Choi, James J.; Wang, Shougang; Tung, Yao-Sheng; Morrison, Barclay; Konofagou, Elisa E.

2009-01-01

Focused ultrasound (FUS) is hereby shown to noninvasively and selectively deliver compounds at pharmacologically relevant molecular weights through the opened blood-brain barrier (BBB). A complete examination on the size of the FUS-induced BBB opening, the spatial distribution of the delivered agents and its dependence on the agent's molecular weight were imaged and quantified using fluorescence microscopy. BBB opening in mice (n=13) was achieved in vivo after systemic administration of microbubbles and subsequent application of pulsed FUS (frequency: 1.525 MHz, peak-rarefactional pressure in situ: 569 kPa) to the left murine hippocampus through the intact skin and skull. BBB-impermeant, fluorescent-tagged dextrans at three distinct molecular weights spanning over several orders of magnitude were systemically administered and acted as model therapeutic compounds. First, dextrans of 3 and 70 kDa were delivered trans-BBB while 2000 kDa dextran was not. Second, compared to 70 kDa dextran, a higher concentration of 3 kDa dextran was delivered through the opened BBB. Third, the 3 and 70 kDa dextrans were both diffusely distributed throughout the targeted brain region. However, high concentrations of 70 kDa dextran appeared more punctated throughout the targeted region. In conclusion, FUS combined with microbubbles opened the BBB sufficiently to allow passage of compounds of at least 70 kDa, but not greater than 2000 kDa, into the brain parenchyma. This noninvasive and localized BBB opening technique could thus provide a unique means for the delivery of compounds of several magnitudes of kDa that include agents with shown therapeutic promise in vitro, but whose in vivo translation has been hampered by their associated BBB impermeability. PMID:19900750

Chirp- and random-based coded ultrasonic excitation for localized blood-brain barrier opening

PubMed Central

Kamimura, HAS; Wang, S; Wu, S-Y; Karakatsani, ME; Acosta, C; Carneiro, AAO; Konofagou, EE

2015-01-01

Chirp- and random-based coded excitation methods have been proposed to reduce standing wave formation and improve focusing of transcranial ultrasound. However, no clear evidence has been shown to support the benefits of these ultrasonic excitation sequences in vivo. This study evaluates the chirp and periodic selection of random frequency (PSRF) coded-excitation methods for opening the blood-brain barrier (BBB) in mice. Three groups of mice (n=15) were injected with polydisperse microbubbles and sonicated in the caudate putamen using the chirp/PSRF coded (bandwidth: 1.5-1.9 MHz, peak negative pressure: 0.52 MPa, duration: 30 s) or standard ultrasound (frequency: 1.5 MHz, pressure: 0.52 MPa, burst duration: 20 ms, duration: 5 min) sequences. T1-weighted contrast-enhanced MRI scans were performed to quantitatively analyze focused ultrasound induced BBB opening. The mean opening volumes evaluated from the MRI were 9.38±5.71 mm3, 8.91±3.91 mm3 and 35.47 ± 5.10 mm3 for the chirp, random and regular sonications, respectively. The mean cavitation levels were 55.40±28.43 V.s, 63.87±29.97 V.s and 356.52±257.15 V.s for the chirp, random and regular sonications, respectively. The chirp and PSRF coded pulsing sequences improved the BBB opening localization by inducing lower cavitation levels and smaller opening volumes compared to results of the regular sonication technique. Larger bandwidths were associated with more focused targeting but were limited by the frequency response of the transducer, the skull attenuation and the microbubbles optimal frequency range. The coded methods could therefore facilitate highly localized drug delivery as well as benefit other transcranial ultrasound techniques that use higher pressure levels and higher precision to induce the necessary bioeffects in a brain region while avoiding damage to the surrounding healthy tissue. PMID:26394091

Ultrasound-Induced Blood-Brain Barrier Opening

PubMed Central

Konofagou, Elisa E.; Tung, Yao-Sheng; Choi, James; Deffieux, Thomas; Baseri, Babak; Vlachos, Fotios

2014-01-01

Over 4 million U.S. men and women suffer from Alzheimer's disease; 1 million from Parkinson's disease; 350,000 from multiple sclerosis (MS); and 20,000 from amyotrophic lateral sclerosis (ALS). Worldwide, these four diseases account for more than 20 million patients. In addition, aging greatly increases the risk of neurodegenerative disease. Although great progress has been made in recent years toward understanding of these diseases, few effective treatments and no cures are currently available. This is mainly due to the impermeability of the blood-brain barrier (BBB) that allows only 5% of the 7000 small-molecule drugs available to treat only a tiny fraction of these diseases. On the other hand, safe and localized opening of the BBB has been proven to present a significant challenge. Of the methods used for BBB disruption shown to be effective, Focused Ultrasound (FUS), in conjunction with microbubbles, is the only technique that can induce localized BBB opening noninvasively and regionally. FUS may thus have a huge impact in trans-BBB brain drug delivery. The primary objective in this paper is to elucidate the interactions between ultrasound, microbubbles and the local microenvironment during BBB opening with FUS, which are responsible for inducing the BBB disruption. The mechanism of the BBB opening in vivo is monitored through the MRI and passive cavitation detection (PCD), and the safety of BBB disruption is assessed using H&E histology at distinct pressures, pulse lengths and microbubble diameters. It is hereby shown that the BBB can be disrupted safely and transiently under specific acoustic pressures (under 0.45 MPa) and microbubble (diameter under 8 μm) conditions. PMID:22201586

Quantitative assessment of the blood-brain barrier opening caused by Streptococcus agalactiae hyaluronidase in a BALB/c mouse model.

PubMed

Luo, Su; Cao, Qing; Ma, Ke; Wang, Zhaofei; Liu, Guangjin; Lu, Chengping; Liu, Yongjie

2017-10-19

Streptococcus agalactiae is a pathogen causing meningitis in animals and humans. However, little is known about the entry of S. agalactiae into brain tissue. In this study, we developed a BALB/c mouse model based on the intravenous injection of β-galactosidase-positive Escherichia coli M5 as an indicator of blood-brain barrier (BBB) opening. Under physiological conditions, the BBB is impermeable to E. coli M5. In pathological conditions caused by S. agalactiae, E. coli M5 is capable of penetrating the brain through a disrupted BBB. The level of BBB opening can be assessed by quantitative measurement of E. coli M5 loads per gram of brain tissue. Further, we used the model to evaluate the role of S. agalactiae hyaluronidase in BBB opening. The inactivation of hylB gene encoding a hyaluronidase, HylB, resulted in significantly decreased E. coli M5 colonization, and the intravenous injection of purified HylB protein induced BBB opening in a dose-dependent manner. This finding verified the direct role of HylB in BBB invasion and traversal, and further demonstrated the practicability of the in vivo mouse model established in this study. This model will help to understand the S. agalactiae-host interactions that are involved in this bacterial traversal of the BBB and to develop efficacious strategies to prevent central nervous system infections.

Characterization of Different Microbubbles in Assisting Focused Ultrasound-Induced Blood-Brain Barrier Opening

NASA Astrophysics Data System (ADS)

Wu, Sheng-Kai; Chu, Po-Chun; Chai, Wen-Yen; Kang, Shih-Tsung; Tsai, Chih-Hung; Fan, Ching-Hsiang; Yeh, Chih-Kuang; Liu, Hao-Li

2017-04-01

Microbubbles (MBs) serve as a critical catalyst to amplify local cavitation in CNS capillary lumen to facilitate focused ultrasound (FUS) to transiently open the blood-brain barrier (BBB). However, limited understanding is available regarding the effect of different microbubbles to induce BBB opening. The aim of this study is to characterize different MBs on their effect in FUS-induced BBB opening. Three MBs, SonoVue, Definity, and USphere, were tested, with 0.4-MHz FUS exposure at 0.62-1.38 of mechanical index (MI) on rats. Evans blue, dynamic contrast-enhanced (DCE) MRI and small-animal ultrasound imaging were used as surrogates to allow molecule-penetrated quantification, BBB-opened observation, and MBs circulation/persistence. Cavitation activity was measured via the passive cavitation detection (PCD) setup to correlate with the exposure level and the histological effect. Under given and identical MB concentrations, the three MBs induced similar and equivalent BBB-opening effects and persistence. In addition, a treatment paradigm by adapting exposure time is proposed to compensate MB decay to retain the persistence of BBB-opening efficiency in multiple FUS exposures. The results potentially improve understanding of the equivalence among MBs in focused ultrasound CNS drug delivery, and provide an effective strategy for securing persistence in this treatment modality.

The Dependence of the Ultrasound-Induced Blood-Brain Barrier Opening Characteristics on Microbubble Size In Vivo

NASA Astrophysics Data System (ADS)

Choi, James J.; Feshitan, Jameel A.; Wang, Shougang; Tung, Yao-Sheng; Baseri, Babak; Borden, Mark A.; Konofagou, Elisa E.

2009-04-01

Recent neuropharmaceutical developments have led to potent disease-modifying drugs. In spite of these advancements, most agents cannot traverse the blood-brain barrier (BBB) and deposit in the brain. Focused ultrasound (FUS) with microbubbles has been shown to induce noninvasive, localized, and transient BBB opening. Although promising, safety and efficacy concerns still remain. Previously reported experiments used conventional imaging contrast agents that have a wide size distribution. In this study, we hypothesize that BBB opening characteristics are dependent on bubble diameter. A 25 μl bolus of in-house manufactured, lipid-shelled bubbles with either 1-2 or 4-5 μm diameter ranges was injected intravenously. Pulsed FUS (frequency: 1.5 MHz, peak-negative pressure: 146-607 kPa, duty cycle: 20%, duration: 1-min) was then applied to the left hippocampus of mice (n = 16) in vivo through the intact skin and skull. MRI or fluorescence microscopy was used to determine BBB opening. Contrast-enhanced (Omniscan™; 0.75 mL; molecular weight: 574 Da) MRI (9.4-T) was acquired on multiple days after sonication to determine BBB opening and closing. Fluorescence microscopy was also used to determine the feasibility of delivering large, 3 kDa dextran compounds through the BBB. The BBB opening acoustic pressure threshold for the 4-5μm bubbles was in the 146-304 kPa range while the threshold for the 1-2μm bubbles was higher. In conclusion, FUS-induced BBB opening and closing was shown to be dependent on the bubble diameter indicating the possibility of specifically designing bubbles to enhance this therapeutic application.

Anesthesia-Induced Hypothermia Attenuates Early-Phase Blood-Brain Barrier Disruption but Not Infarct Volume following Cerebral Ischemia.

PubMed

Liu, Yu-Cheng; Lee, Yu-Da; Wang, Hwai-Lee; Liao, Kate Hsiurong; Chen, Kuen-Bao; Poon, Kin-Shing; Pan, Yu-Ling; Lai, Ted Weita

2017-01-01

Blood-brain barrier (BBB) disruption is thought to facilitate the development of cerebral infarction after a stroke. In a typical stroke model (such as the one used in this study), the early phase of BBB disruption reaches a peak 6 h post-ischemia and largely recovers after 8-24 h, whereas the late phase of BBB disruption begins 48-58 h post-ischemia. Because cerebral infarct develops within 24 h after the onset of ischemia, and several therapeutic agents have been shown to reduce the infarct volume when administered at 6 h post-ischemia, we hypothesized that attenuating BBB disruption at its peak (6 h post-ischemia) can also decrease the infarct volume measured at 24 h. We used a mouse stroke model obtained by combining 120 min of distal middle cerebral arterial occlusion (dMCAo) with ipsilateral common carotid arterial occlusion (CCAo). This model produced the most reliable BBB disruption and cerebral infarction compared to other models characterized by a shorter duration of ischemia or obtained with dMCAO or CCAo alone. The BBB permeability was measured by quantifying Evans blue dye (EBD) extravasation, as this tracer has been shown to be more sensitive for the detection of early-phase BBB disruption compared to other intravascular tracers that are more appropriate for detecting late-phase BBB disruption. We showed that a 1 h-long treatment with isoflurane-anesthesia induced marked hypothermia and attenuated the peak of BBB disruption when administered 6 h after the onset of dMCAo/CCAo-induced ischemia. We also demonstrated that the inhibitory effect of isoflurane was hypothermia-dependent because the same treatment had no effect on ischemic BBB disruption when the mouse body temperature was maintained at 37°C. Importantly, inhibiting the peak of BBB disruption by hypothermia had no effect on the volume of brain infarct 24 h post-ischemia. In conclusion, inhibiting the peak of BBB disruption is not an effective neuroprotective strategy, especially in comparison to the inhibitors of the neuronal death signaling cascade; these, in fact, can attenuate the infarct volume measured at 24 h post-ischemia when administered at 6 h in our same stroke model.

Platelet activating factor induces transient blood-brain barrier opening to facilitate edaravone penetration into the brain.

PubMed

Fang, Weirong; Zhang, Rui; Sha, Lan; Lv, Peng; Shang, Erxin; Han, Dan; Wei, Jie; Geng, Xiaohan; Yang, Qichuan; Li, Yunman

2014-03-01

The blood-brain barrier (BBB) greatly limits the efficacy of many neuroprotective drugs' delivery to the brain, so improving drug penetration through the BBB has been an important focus of research. Here we report that platelet activating factor (PAF) transiently opened BBB and facilitated neuroprotectant edaravone penetration into the brain. Intravenous infusion with PAF induced a transient BBB opening in rats, reflected by increased Evans blue leakage and mild edema formation, which ceased within 6 h. Furthermore, rat regional cerebral blood flow (rCBF) declined acutely during PAF infusion, but recovered slowly. More importantly, this transient BBB opening significantly increased the penetration of edaravone into the brain, evidenced by increased edaravone concentrations in tissue interstitial fluid collected by microdialysis and analyzed by Ultra-performance liquid chromatograph combined with a hybrid quadrupole time-of-flight mass spectrometer (UPLC-MS/MS). Similarly, incubation of rat brain microvessel endothelial cells monolayer with 1 μM PAF for 1 h significantly increased monolayer permeability to (125)I-albumin, which recovered 1 h after PAF elimination. However, PAF incubation with rat brain microvessel endothelial cells for 1 h did not cause detectable cytotoxicity, and did not regulate intercellular adhesion molecule-1, matrix-metalloproteinase-9 and P-glycoprotein expression. In conclusion, PAF could induce transient and reversible BBB opening through abrupt rCBF decline, which significantly improved edaravone penetration into the brain. Platelet activating factor (PAF) transiently induces BBB dysfunction and increases BBB permeability, which may be due to vessel contraction and a temporary decline of regional cerebral blood flow (rCBF) triggered by PAF. More importantly, the PAF induced transient BBB opening facilitates neuroprotectant edaravone penetration into brain. The results of this study may provide a new approach to improve drug delivery into the brain. © 2013 International Society for Neurochemistry.

Photoacoustic micro-imaging of focused ultrasound induced blood-brain-barrier opening in a rat model

NASA Astrophysics Data System (ADS)

Wang, Po-Hsun; Hsu, Po-Hung; Liu, Hao-Li; Wang, Churng-Ren Chris; Li, Meng-Lin

2010-02-01

Blood brain barrier (BBB) prevents most of the drug from transmitting into the brain tissue and decreases the treatment performance for brain disease. One of the methods to overcome the difficulty of drug delivery is to locally increase the permeability of BBB with high-intensity focused ultrasound. In this study, we have investigated the feasibility of photoacoustic microscopy of focused-ultrasound induced BBB opening in a rat model in vivo with gold nanorods (AuNRs) as a contrast agent. This study takes advantage of the strong near-infrared absorption of AuNRs and their extravasation tendency from BBB opening foci due to their nano-scale size. Before the experiments, craniotomy was performed on rats to provide a path for focused ultrasound beam. Localized BBB opening at the depth of about 3 mm from left cortex of rat brains was achieved by delivering 1.5 MHz focused ultrasound energy into brain tissue in the presence of microbubbles. PEGylated AuNRs with a peak optical absorption at ~800 nm were then intravenously administered. Pre-scan prior to BBB disruption and AuNR injection was taken to mark the signal background. After injection, the distribution of AuNRs in rat brains was monitored up to 2 hours. Experimental results show that imaging AuNRs reveals BBB disruption area in left brains while there are no changes observed in the right brains. From our results, photoacoustic imaging plus AuNRs shows the promise as a novel monitoring strategy in identifying the location and variation of focused-ultrasound BBB-opening in a rat model.

Memory is preserved in older adults taking AT1 receptor blockers.

PubMed

Ho, Jean K; Nation, Daniel A

2017-04-26

Prior work suggests that some but not all antihypertensive treatments may benefit cognition and risk for Alzheimer's disease, independent of stroke. Angiotensin II receptor blockers (ARBs) have been highlighted as one antihypertensive drug class that may confer greatest benefit. The participants comprised 1626 nondemented adults, aged 55-91 years, recruited from Alzheimer's Disease Neuroimaging Initiative sites. Three groups were compared: ARB users (HTN-ARBs), other antihypertensive drug users (HTN-Other), and normotensives. In post hoc analyses, we also examined (1) users of ARBs and angiotensin-converting enzyme inhibitors (ACEIs), (2) users of blood-brain barrier (BBB)-crossing ARBs and users of non-BBB-crossing ARBs, and (3) users of BBB-crossing ARBs and ACEIs (BBB crossers) and users of non-BBB-crossing ARBs and ACEIs (BBB noncrossers). Groups were compared regarding cognition and magnetic resonance imaging measures of brain volume and white matter hyperintensities (WMH), using analysis of covariance and multilevel models. At baseline, the HTN-Other group performed worse than normotensives on Rey Auditory Verbal Learning Test (RAVLT) Immediate Recall (p = 0.002), Delayed Recall (p < 0.001), Recognition Memory (p = 0.001), and Trails A (p < 0.001) and B (p = 0.01). ARB users performed better than the HTN-Other group on Recognition Memory (p = 0.04) and worse than normotensives on Trails A (p = 0.04). The HTN-Other group performed worse than normotensives on Logical Memory Immediate (p = 0.02) and Delayed Recall over the 3-year follow-up (p = 0.007). Over the follow-up period, those taking BBB-crossing ARBs performed better than the HTN-Other group on AVLT Delayed Recall (p = 0.04), Logical Memory Immediate (p = 0.02), and Delayed Recall (p = 0.05). They also had fewer WMH than the HTN-Other group (p = 0.008) and those taking non-BBB-crossing ARBs (p = 0.05). There were no group differences in brain volume. Users of BBB-crossing medications (ARBs or ACEIs) showed better performance on AVLT Delayed Recall over time than all other groups, including normotensives (all p < 0.01), and had less WMH volume over time than the BBB noncrossers group (p = 0.03), although they had more WMH volume than normotensives (p = 0.01). The BBB noncrossers group performed worse than normotensives on Logical Memory Delayed Recall over time (p = 0.01), but the BBB crossers group was not significantly different (p = 0.13). Hypertensive participants demonstrated worse baseline memory and executive function, as well as greater memory decline, over the 3-year follow-up than normotensives, unless they were ARB users, who showed preserved memory compared with those taking other antihypertensive drugs. Users of BBB-crossing ARBs showed superior memory performance over time compared with other antihypertensive drug users and had less WMH volume. Users of BBB-crossing medications (ARBs or ACEIs) showed better list-learning memory performance over time than all other groups, including normotensives, and had less WMH volume over time than users of non-BBB-crossing medications. These findings demonstrate that ARBs, especially those of the BBB-crossing variety, are associated with greater memory preservation and less WMH volume than other antihypertensive medications.

Gold-nanorod contrast-enhanced photoacoustic micro-imaging of focused-ultrasound induced blood-brain-barrier opening in a rat model

NASA Astrophysics Data System (ADS)

Wang, Po-Hsun; Liu, Hao-Li; Hsu, Po-Hung; Lin, Chia-Yu; Chris Wang, Churng-Ren; Chen, Pin-Yuan; Wei, Kuo-Chen; Yen, Tzu-Chen; Li, Meng-Lin

2012-06-01

In this study, we develop a novel photoacoustic imaging technique based on gold nanorods (AuNRs) for quantitatively monitoring focused-ultrasound (FUS) induced blood-brain barrier (BBB) opening in a rat model in vivo. This study takes advantage of the strong near-infrared absorption (peak at ~800 nm) of AuNRs and the extravasation tendency from BBB opening foci due to their nano-scale size to passively label the BBB disruption area. Experimental results show that AuNR contrast-enhanced photoacoustic microscopy (PAM) successfully reveals the spatial distribution and temporal response of BBB disruption area in the rat brains. The quantitative measurement of contrast enhancement has potential to estimate the local concentration of AuNRs and even the dosage of therapeutic molecules when AuNRs are further used as nano-carrier for drug delivery or photothermal therapy. The photoacoustic results also provide complementary information to MRI, being helpful to discover more details about FUS induced BBB opening in small animal models.

Application of optical coherence tomography for in vivo monitoring of the meningeal lymphatic vessels during opening of blood-brain barrier: mechanisms of brain clearing

NASA Astrophysics Data System (ADS)

Semyachkina-Glushkovskaya, Oxana; Abdurashitov, Arkady; Dubrovsky, Alexander; Bragin, Denis; Bragina, Olga; Shushunova, Nataliya; Maslyakova, Galina; Navolokin, Nikita; Bucharskaya, Alla; Tuchin, Valery; Kurths, Juergen; Shirokov, Alexander

2017-12-01

The meningeal lymphatic vessels were discovered 2 years ago as the drainage system involved in the mechanisms underlying the clearance of waste products from the brain. The blood-brain barrier (BBB) is a gatekeeper that strongly controls the movement of different molecules from the blood into the brain. We know the scenarios during the opening of the BBB, but there is extremely limited information on how the brain clears the substances that cross the BBB. Here, using the model of sound-induced opening of the BBB, we clearly show how the brain clears dextran after it crosses the BBB via the meningeal lymphatic vessels. We first demonstrate successful application of optical coherence tomography (OCT) for imaging of the lymphatic vessels in the meninges after opening of the BBB, which might be a new useful strategy for noninvasive analysis of lymphatic drainage in daily clinical practice. Also, we give information about the depth and size of the meningeal lymphatic vessels in mice. These new fundamental data with the applied focus on the OCT shed light on the mechanisms of brain clearance and the role of lymphatic drainage in these processes that could serve as an informative platform for a development of therapy and diagnostics of diseases associated with injuries of the BBB such as stroke, brain trauma, glioma, depression, or Alzheimer disease.

Borneol, a novel agent that improves central nervous system drug delivery by enhancing blood-brain barrier permeability.

PubMed

Zhang, Qun-Lin; Fu, Bingmei M; Zhang, Zhang-Jin

2017-11-01

The clinical application of central nervous system (CNS) drugs is limited by their poor bioavailability due to the blood-brain barrier (BBB). Borneol is a naturally occurring compound in a class of 'orifice-opening' agents often used for resuscitative purposes in traditional Chinese medicine. A growing body of evidence confirms that the 'orifice-opening' effect of borneol is principally derived from opening the BBB. Borneol is therefore believed to be an effective adjuvant that can improve drug delivery to the brain. The purpose of this paper is to provide a comprehensive review of information accumulated over the past two decades on borneol's chemical features, sources, toxic and kinetic profiles, enhancing effects on BBB permeability and their putative mechanisms, improvements in CNS drug delivery, and pharmaceutical forms. The BBB-opening effect of borneol is a reversible physiological process characterized by rapid and transient penetration of the BBB and highly specific brain regional distribution. Borneol also protects the structural integrity of the BBB against pathological damage. The enhancement of the BBB permeability is associated with the modulation of multiple ATP-binding cassette transporters, including P-glycoprotein; tight junction proteins; and predominant enhancement of vasodilatory neurotransmitters. Systemic co-administration with borneol improves drug delivery to the brain in a region-, dose- and time-dependent manner. Several pharmaceutical forms of borneol have been developed to improve the kinetic and toxic profiles of co-administered drugs and enhance their delivery to the brain. Borneol is a promising novel agent that deserves further development as a BBB permeation enhancer for CNS drug delivery.

Focused ultrasound-mediated noninvasive blood-brain barrier modulation: preclinical examination of efficacy and safety in various sonication parameters.

PubMed

Shin, Jaewoo; Kong, Chanho; Cho, Jae Sung; Lee, Jihyeon; Koh, Chin Su; Yoon, Min-Sik; Na, Young Cheol; Chang, Won Seok; Chang, Jin Woo

2018-02-01

OBJECTIVE The application of pharmacological therapeutics in neurological disorders is limited by the ability of these agents to penetrate the blood-brain barrier (BBB). Focused ultrasound (FUS) has recently gained attention for its potential application as a method for locally opening the BBB and thereby facilitating drug delivery into the brain parenchyma. However, this method still requires optimization to maximize its safety and efficacy for clinical use. In the present study, the authors examined several sonication parameters of FUS influencing BBB opening in small animals. METHODS Changes in BBB permeability were observed during transcranial sonication using low-intensity FUS in 20 adult male Sprague-Dawley rats. The authors examined the effects of FUS sonication with different sonication parameters, varying acoustic pressure, center frequency, burst duration, microbubble (MB) type, MB dose, pulse repetition frequency (PRF), and total exposure time. The focal region of BBB opening was identified by Evans blue dye. Additionally, H & E staining was used to identify blood vessel damage. RESULTS Acoustic pressure amplitude and burst duration were closely associated with enhancement of BBB opening efficiency, but these parameters were also highly correlated with tissue damage in the sonicated region. In contrast, MB types, MB dose, total exposure time, and PRF had an influence on BBB opening without conspicuous tissue damage after FUS sonication. CONCLUSIONS The study aimed to identify these influential conditions and provide safety and efficacy values for further studies. Future work based on the current results is anticipated to facilitate the implementation of FUS sonication for drug delivery in various CNS disease states in the near future.

The dynamic of FUS-induced BBB Opening in Mouse Brain assessed by contrast enhanced MRI

NASA Astrophysics Data System (ADS)

Jenne, Jürgen W.; Krafft, Axel J.; Maier, Florian; Krause, Marie N.; Kleber, Susanne; Huber, Peter E.; Martin-Villalba, Ana; Bock, Michael

2010-03-01

Focused ultrasound (FUS) in combination with the administration of gas-filled microbubbles, can induce a localized and reversible opening of the blood brain barrier (BBB). Contrast enhanced magnetic resonance imaging (MRI) has been demonstrated as a precise tool to monitor such a local BBB disruption. However, the opening/closing mechanisms of the BBB with FUS are still largely unknown. In this ongoing project, we study the BBB opening dynamics in mouse brain comparing an interstitial and an intravascular MR contrast agent (CA). FUS in mouse brain was performed with an MRI compatible treatment setup (1.7 MHz fix-focus US transducer, f' = 68 mm, NA = 0.44; focus: 8.1 mm length; O/ = 1.1 mm) in a 1.5 T whole body MRI system. For BBB opening, forty 10 ms-long FUS-pulses were applied at a repetition rate of 1 Hz at 1 MPa. The i.v. administration of the micro bubbles (50 μl SonoVue®) was started simultaneously with FUS exposure. To analyze the BBB opening process, short-term and long-term MRI signal dynamics of the interstitial MR contrast agent Magnevist® and the intravascular CA Vasovist® (Bayer-Schering) were studied. To assess short-term signal dynamics, T1-weighted inversion recovery turbo FLASH images (1s) were repeatedly acquired. Repeated 3D FLASH acquisitions (90 s) were used to assess long-term MRI signal dynamics. The short-term MRI signal enhancements showed comparable time constants for both types of MR contrast agents: 1.1 s (interstitial) vs. 0.8 s (intravascular). This time constant may serve as a time constant of the BBB opening process with the given FUS exposure parameters. For the long-term signal dynamics the intravascular CA (62±10 min) showed a fife times greater time constant as the interstitial contrast agent (12±10 min). This might be explained by the high molecular weight (˜60 kDa) of the intravascular Vasovist due to its reversible binding to blood serum albumin resulting in a prolonged half-life in the blood stream compared to the interstitial CA. As the intravascular CA offers a much longer time window for therapy assessment, FUS-BBB therapy control with an intravascular CA might be favorable.

Transcranial MRI-guided FUS-induced BBB opening in the rat brain

NASA Astrophysics Data System (ADS)

Treat, Lisa H.; McDannold, Nathan J.; Hynynen, Kullervo

2004-05-01

The blood-brain barrier (BBB) has been a major limitation in treating diseases of the brain because therapeutic agents are either unable to penetrate or have dose-limiting side effects in diffuse opening of the BBB. A previous study demonstrated that focused ultrasound (FUS) can locally open the BBB in a rabbit model when a piece of skull is removed and that magnetic resonance imaging (MRI) can be used to guide and monitor the procedure. This study examined whether the same desired effect of local BBB disruption can be achieved by applying FUS through an intact skull in a rat model. Twenty-eight Sprague-Dawley rats were anesthetized, shaved, and sonicated at four focal locations in the brain, using a 1.5-MHz focused transducer. Contrast-enhanced MR images were obtained before and after sonication. The images indicated contrast agent penetration at the focal coordinates following Optison-enhanced sonication. This study demonstrated that the distortion of the ultrasound beam by the rat skull was not significant enough to inhibit focal BBB opening. Subsequent experiments using MRI-guided FUS to aid in targeted drug delivery to brain tumors in a rodent model could thus be performed more efficiently without cranial surgery. [Research funded by NIH Grant No. CA76550.

Evaluation of laser speckle contrast imaging as an intrinsic method to monitor blood brain barrier integrity

PubMed Central

Dufour, Suzie; Atchia, Yaaseen; Gad, Raanan; Ringuette, Dene; Sigal, Iliya; Levi, Ofer

2013-01-01

The integrity of the blood brain barrier (BBB) can contribute to the development of many brain disorders. We evaluate laser speckle contrast imaging (LSCI) as an intrinsic modality for monitoring BBB disruptions through simultaneous fluorescence and LSCI with vertical cavity surface emitting lasers (VCSELs). We demonstrated that drug-induced BBB opening was associated with a relative change of the arterial and venous blood velocities. Cross-sectional flow velocity ratio (veins/arteries) decreased significantly in rats treated with BBB-opening drugs, ≤0.81 of initial values. PMID:24156049

Trans-cranial opening of the blood-brain barrier in targeted regions using a stereotaxic brain atlas and focused ultrasound energy.

PubMed

Bing, Chenchen; Ladouceur-Wodzak, Michelle; Wanner, Clinton R; Shelton, John M; Richardson, James A; Chopra, Rajiv

2014-01-01

The blood-brain barrier (BBB) protects the brain by preventing the entry of large molecules; this poses a major obstacle for the delivery of drugs to the brain. A novel technique using focused ultrasound (FUS) energy combined with microbubble contrast agents has been widely used for non-invasive trans-cranial BBB opening. Traditionally, FUS research is conducted with magnetic resonance imaging (MRI) guidance, which is expensive and poses physical limitations due to the magnetic field. A system that could allow researchers to test brain therapies without MR intervention could facilitate and accelerate translational research. In this study, we present a novel FUS system that uses a custom-built FUS generator mounted on a motorized stereotaxic apparatus with embedded brain atlas to locally open the BBB in rodents. The system was initially characterized using a tissue-mimicking phantom. Rodent studies were also performed to evaluate whether non-invasive, localized BBB opening could be achieved using brain atlas-based targeting. Brains were exposed to pulsed focused ultrasound energy at 1.06 MHz in rats and 3.23 MHz in mice, with the focal pressure estimated to be 0.5-0.6 MPa through the skull. BBB opening was confirmed in gross tissue sections by the presence of Evans blue leakage in the exposed region of the brain and by histological assessment. The targeting accuracy of the stereotaxic system was better than 0.5 mm in the tissue-mimicking phantom. Reproducible localized BBB opening was verified with Evans blue dye leakage in 32/33 rats and had a targeting accuracy of ±0.3 mm. The use of higher frequency exposures in mice enabled a similar precision of localized BBB opening as was observed with the low frequency in the rat model. With this dedicated small-animal motorized stereotaxic-FUS system, we achieved accurate targeting of focused ultrasound exposures in the brain for non-invasive opening of the BBB. This system can be used as an alternative to MR-guided FUS and offers researchers the ability to perform efficient studies (30 min per experiment including preparation) at a reduced cost in a conventional laboratory environment.

Neuronavigation-guided focused ultrasound-induced blood-brain barrier opening: A preliminary study in swine

NASA Astrophysics Data System (ADS)

Liu, Hao-Li; Tsai, Hong-Chieh; Lu, Yu-Jen; Wei, Kuo-Chen

2012-11-01

FUS-induced BBB opening is a promising technique for noninvasive and local delivery of drugs into the brain. Here we propose the novel use of a neuronavigation system to guide the FUS-induced BBB opening procedure, and investigate its feasibility in vivo in large animals. We developed an interface between the neuronavigator and FUS to allow guidance of the focal energy produced by the FUS transducer. The system was tested in 29 pigs by more than 40 sonication procedures and evaluated by MRI. Gd-DTPA concentration was quantitated in vivo by MRI R1 relaxometry and compared by ICP-OES assay. Brain histology after FUS exposure was investigated by HE and TUNEL staining. Neuronavigation could successfully guide the focal beam with comparable precision to neurosurgical stereotactic procedures (2.3 ± 0.9 mm). FUS pressure of 0.43 MPa resulted in consistent BBB-opening. Neuronavigation-guided BBB-opening increased Gd-DTPA deposition by up to 1.83 mM (140% increase). MR relaxometry demonstrated high correlation to ICP-OES measurements (r2 = 0.822), suggesting that Gd-DTPA deposition can be directly measured by imaging. Neuronavigation could provide sufficient precision for guiding FUS to temporally and locally open the BBB. Gd-DTPA deposition in the brain could be quantified by MR relaxometry, providing a potential tool for the in vivo quantification of therapeutic agents in CNS disease treatment.

Multi-modality safety assessment of blood-brain barrier opening using focused ultrasound and definity microbubbles: a short-term study.

PubMed

Baseri, Babak; Choi, James J; Tung, Yao-Sheng; Konofagou, Elisa E

2010-09-01

As a potentially viable method of brain drug delivery, the safety profile of blood-brain barrier (BBB) opening using focused ultrasound (FUS) and ultrasound contrast agents (UCA) needs to be established. In this study, we provide a short-term (30-min or 5-h survival) histological assessment of murine brains undergoing FUS-induced BBB opening. Forty-nine mice were intravenously injected with Definity microbubbles (0.05 microL/kg) and sonicated under the following parameters: frequency of 1.525 MHz, pulse length of 20 ms, pulse repetition frequency of 10 Hz, peak rarefactional acoustic pressures of 0.15-0.98 MPa and two 30-s sonication intervals with an intermittent 30-s delay. The BBB opening threshold was found to be 0.15-0.3 MPa based on fluorescence and magnetic resonance imaging of systemically injected tracers. Analysis of three histological measures in hematoxylin and eosin-stained sections revealed the safest acoustic pressure to be within the range of 0.3-0.46 MPa in all examined time periods post sonication. Across different pressure amplitudes, only the samples 30 min post opening showed significant difference (p < 0.05) in the average number of distinct damaged sites, microvacuolated sites, dark neurons and sites with extravasated erythrocytes. Enhanced fluorescence around severed microvessels was also noted and found to be associated with the largest tissue effects, whereas mildly diffuse BBB opening with uniform fluorescence in the parenchyma was associated with no or mild tissue injury. Region-specific areas of the sonicated brain (thalamus, hippocampal fissure, dentate gyrus and CA3 area of hippocampus) exhibited variation in fluorescence intensity based on the position, orientation and size of affected vessels. The results of this short-term histological analysis demonstrated the feasibility of a safe FUS-UCA-induced BBB opening under a specific set of sonication parameters and provided new insights on the mechanism of BBB opening.

Perifocal and remote blood-brain barrier disruption in cortical photothrombotic ischemic lesion and its modulation by the choice of anesthesia.

PubMed

Krysl, D; Deykun, K; Lambert, L; Pokorny, J; Mares, J

2012-04-01

We assessed blood-brain barrier (BBB) disruption in early stage of photothrombotic focal cerebral ischemia in the rat. We specifically looked for contralateral changes in BBB permeability and tested the influence of two anesthetics on the results. Adult Wistar rats were randomly anesthetized with pentobarbital (PB) or ketamine-xylazine (KX). Rats received intravenously (i.v.) Rose Bengal followed by Evans Blue (EB). Stereotactically defined spots on denuded skull were irradiated by laser (532 nm) for 18 min. Twenty four hours later, rats were killed, brains perfused, fixated, sectioned and slices analyzed by fluorescence microscopy. Volume of necrosis and volume of EB-albumin extravasation were calculated. Evidence of BBB breakdown in remote brain areas was sought and compared to sham handled controls. BBB disruption was consistently present, frequently with EB-albumin accumulating cells. Total lesion volume did not significantly differ among groups (TLVPB=9.4±1.3 mm³ vs. TLVKX=8.3±2.1 mm³); same was true for the volume of necrosis (NVPB=5.1±0.7 mm³ vs. NVKX=6.3±1.9 mm³). However, volume of EB-albumin extravasation area was significantly smaller in KX group (EBEVPB=4.3±0.8 mm³ vs. EBEVKX=2.0±0.5 mm³; p=0.0293). Median background EB-fluorescence signal density was higher in PB group (p<0.0001). Furthermore, regional increase in EB-fluorescence was found in two animals in PB group. Our study shows that anesthesia with NMDA-antagonist ketamine and α2-adrenergic agonist xylazine may reduce BBB breakdown in photothrombosis. Pentobarbital anesthesia lead to increased BBB permeability in the contralateral hemisphere.

Time course of hyperosmolar opening of the blood-brain and blood-CSF barriers in spontaneously hypertensive rats.

PubMed

Al-Sarraf, Hameed; Ghaaedi, Firuz; Redzic, Zoran

2007-01-01

The time course of blood-brain barrier (BBB) and blood-CSF barrier (BCSFB) responses to hyperosmolar mannitol infusion (HMI; 1.6 M) during chronic hypertension was investigated using (14)C-sucrose as a marker of barrier integrity. (14)C-sucrose entry into CSF of both spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats 2 min after HMI increased approximately 7-fold compared to their respective control. The volume of distribution (V(d)) of (14)C-sucrose into brain cortex of SHR increased 13-fold 2 min after HMI while that in WKY rats increased only 4-fold. After HMI V(d) of (14)C-sucrose into the cortex of WKY, and CSF of both SHR and WKY remained steadily greater than their corresponding control for up to 30 min (p < 0.01), whereas in the cortex of SHR the V(d) of (14)C-sucrose reached control values 20 min after HMI (p > 0.05), indicating that after HMI the increase in paracellular diffusion of (14)C-sucrose into SHR cortex was not persistent, in contrast to WKY rats and CSF of both SHR and WKY rats. Electron microscopy of the brain cortex after HMI showed capillary endothelial cell shrinkage and perivascular swellings in the brain cortex, and in the choroid plexus opening of tight junctions were observed. Our results indicate disruption of both the BBB and the BCSFB after HMI in both SHR and WKY rats. The disruption remained persistent up to 25 min after HMI at the BBB of WKY rats and BCSFB in both animal groups, while in SHR the protective function of the BBB returned to control values 20 min after HMI. Copyright 2007 S. Karger AG, Basel.

Focused Ultrasound-Induced Blood–Brain Barrier Opening to Enhance Temozolomide Delivery for Glioblastoma Treatment: A Preclinical Study

PubMed Central

Wei, Kuo-Chen; Chu, Po-Chun; Wang, Hay-Yan Jack; Huang, Chiung-Yin; Chen, Pin-Yuan; Tsai, Hong-Chieh; Lu, Yu-Jen; Lee, Pei-Yun; Tseng, I-Chou; Feng, Li-Ying; Hsu, Peng-Wei; Yen, Tzu-Chen; Liu, Hao-Li

2013-01-01

The purpose of this study is to assess the preclinical therapeutic efficacy of magnetic resonance imaging (MRI)-monitored focused ultrasound (FUS)-induced blood-brain barrier (BBB) disruption to enhance Temozolomide (TMZ) delivery for improving Glioblastoma Multiforme (GBM) treatment. MRI-monitored FUS with microbubbles was used to transcranially disrupt the BBB in brains of Fisher rats implanted with 9L glioma cells. FUS-BBB opening was spectrophotometrically determined by leakage of dyes into the brain, and TMZ was quantitated in cerebrospinal fluid (CSF) and plasma by LC-MS\\MS. The effects of treatment on tumor progression (by MRI), animal survival and brain tissue histology were investigated. Results demonstrated that FUS-BBB opening increased the local accumulation of dyes in brain parenchyma by 3.8-/2.1-fold in normal/tumor tissues. Compared to TMZ alone, combined FUS treatment increased the TMZ CSF/plasma ratio from 22.7% to 38.6%, reduced the 7-day tumor progression ratio from 24.03 to 5.06, and extended the median survival from 20 to 23 days. In conclusion, this study provided preclinical evidence that FUS BBB-opening increased the local concentration of TMZ to improve the control of tumor progression and animal survival, suggesting its clinical potential for improving current brain tumor treatment. PMID:23527068

Development, Characterization, and Implementation of a System for Focused Ultrasound-Mediated Blood-Brain Barrier Opening in Mice

NASA Astrophysics Data System (ADS)

Valdez, Michael Aaron

The blood-brain barrier BBB refers to the set of specialized endothelial cells that line the vasculature in the brain and effectively control movement of molecules into and out of the brain. While necessary for proper brain function, the BBB blocks 98% of drugs from entering the brain and is the most significant barrier to developing therapies for neurodegenerative diseases. Active transport allows some specific molecules to cross the BBB, but therapeutic development using this route has had limited success. A number of techniques have been used to bypass the BBB, but are often highly invasive and ineffective. Over the last two decades, a minimally invasive technique to transiently open the BBB has been under development that utilizes transcranial focused ultrasound (FUS) in combination with intravascular microbubble contrast agents. This method is often carried out in conjunction with magnetic resonance imaging (MRI) to guide and assess BBB opening and has been referred to as MRI guided FUS (MRgFUS). Because of the utility of mouse models of neurological disease and the exploratory nature of MRgFUS, systems that allow BBB opening in mice are a useful and necessary tool to develop and evaluate this method for clinical application. In this dissertation project, a custom built, cost-effective FUS system for opening the BBB in mice was developed, with the objective of using this device to deliver therapeutics to the brain. Being a custom device, it was necessary to evaluate the ultrasound output, verify in vivo safety, and anticipate the therapeutic effect. The scope of the work herein consists of the design, construction, and evaluation of system that fulfills these requirements. The final constructed system cost was an order of magnitude less than any commercially available MRgFUS system. At this low price point, the hardware could allow the implementation of the methodology in many more research areas than previously possible. Additionally, to anticipate the therapeutic effect, molecules of pharmacologically-relevant sizes were delivered to brain with a novel, multispectral approach. Results demonstrated that the device was able to safely open the BBB, and macromolecule delivery showed that both molecule size and FUS pressure both influence the amount and distribution of molecules in the brain. Using different ultrasound pressures, the threshold for BBB opening was found to be ≥ 180 kPa (0.13 MI). The threshold for damage was found to be ≥ 420 kPa (0.30 MI), and was minor at this pressure, but extensive for higher pressure (870 kPa, 0.62 MI), in which minor damage was caused by this pressure. Performing a novel implementation of a diffusion model on the fluorescence images of 500, 70, and 3 kDa dextran resulted in calculated diffusion coefficients of 0.032 +/- 0.015, 12 +/- 6.0, and 0.13 +/- 0.094 square microns per second, respectively.

Paramagnetic perfluorocarbon-filled albumin-(Gd-DTPA) microbubbles for the induction of focused-ultrasound-induced blood-brain barrier opening and concurrent MR and ultrasound imaging

NASA Astrophysics Data System (ADS)

Liao, Ai-Ho; Liu, Hao-Li; Su, Chia-Hao; Hua, Mu-Yi; Yang, Hung-Wei; Weng, Yu-Ting; Hsu, Po-Hung; Huang, Sheng-Min; Wu, Shih-Yen; Wang, Hsin-Ell; Yen, Tzu-Chen; Li, Pai-Chi

2012-05-01

This paper presents new albumin-shelled Gd-DTPA microbubbles (MBs) that can concurrently serve as a dual-modality contrast agent for ultrasound (US) imaging and magnetic resonance (MR) imaging to assist blood-brain barrier (BBB) opening and detect intracerebral hemorrhage (ICH) during focused ultrasound brain drug delivery. Perfluorocarbon-filled albumin-(Gd-DTPA) MBs were prepared with a mean diameter of 2320 nm and concentration of 2.903×109 MBs ml-1 using albumin-(Gd-DTPA) and by sonication with perfluorocarbon (C3F8) gas. The albumin-(Gd-DTPA) MBs were then centrifuged and the procedure was repeated until the free Gd3+ ions were eliminated (which were detected by the xylenol orange sodium salt solution). The albumin-(Gd-DTPA) MBs were also characterized and evaluated both in vitro and in vivo by US and MR imaging. Focused US was used with the albumin-(Gd-DTPA) MBs to induce disruption of the BBB in 18 rats. BBB disruption was confirmed with contrast-enhanced T1-weighted turbo-spin-echo sequence MR imaging. Heavy T2*-weighted 3D fast low-angle shot sequence MR imaging was used to detect ICH. In vitro US imaging experiments showed that albumin-(Gd-DTPA) MBs can significantly enhance the US contrast in T1-, T2- and T2*-weighted MR images. The r1 and r2 relaxivities for Gd-DTPA were 7.69 and 21.35 s-1mM-1, respectively, indicating that the MBs represent a positive contrast agent in T1-weighted images. In vivo MR imaging experiments on 18 rats showed that focused US combined with albumin-(Gd-DTPA) MBs can be used to both induce disruption of the BBB and detect ICH. To compare the signal intensity change between pure BBB opening and BBB opening accompanying ICH, albumin-(Gd-DTPA) MB imaging can provide a ratio of 5.14 with significant difference (p = 0.026), whereas Gd-DTPA imaging only provides a ratio of 2.13 and without significant difference (p = 0.108). The results indicate that albumin-(Gd-DTPA) MBs have potential as a US/MR dual-modality contrast agent for BBB opening and differentiating focused-US-induced BBB opening from ICH, and can monitor the focused ultrasound brain drug delivery process.

Paramagnetic perfluorocarbon-filled albumin-(Gd-DTPA) microbubbles for the induction of focused-ultrasound-induced blood-brain barrier opening and concurrent MR and ultrasound imaging.

PubMed

Liao, Ai-Ho; Liu, Hao-Li; Su, Chia-Hao; Hua, Mu-Yi; Yang, Hung-Wei; Weng, Yu-Ting; Hsu, Po-Hung; Huang, Sheng-Min; Wu, Shih-Yen; Wang, Hsin-Ell; Yen, Tzu-Chen; Li, Pai-Chi

2012-05-07

This paper presents new albumin-shelled Gd-DTPA microbubbles (MBs) that can concurrently serve as a dual-modality contrast agent for ultrasound (US) imaging and magnetic resonance (MR) imaging to assist blood-brain barrier (BBB) opening and detect intracerebral hemorrhage (ICH) during focused ultrasound brain drug delivery. Perfluorocarbon-filled albumin-(Gd-DTPA) MBs were prepared with a mean diameter of 2320 nm and concentration of 2.903×10(9) MBs ml(-1) using albumin-(Gd-DTPA) and by sonication with perfluorocarbon (C(3)F(8)) gas. The albumin-(Gd-DTPA) MBs were then centrifuged and the procedure was repeated until the free Gd(3+) ions were eliminated (which were detected by the xylenol orange sodium salt solution). The albumin-(Gd-DTPA) MBs were also characterized and evaluated both in vitro and in vivo by US and MR imaging. Focused US was used with the albumin-(Gd-DTPA) MBs to induce disruption of the BBB in 18 rats. BBB disruption was confirmed with contrast-enhanced T(1)-weighted turbo-spin-echo sequence MR imaging. Heavy T(2)*-weighted 3D fast low-angle shot sequence MR imaging was used to detect ICH. In vitro US imaging experiments showed that albumin-(Gd-DTPA) MBs can significantly enhance the US contrast in T(1)-, T(2)- and T(2)*-weighted MR images. The r(1) and r(2) relaxivities for Gd-DTPA were 7.69 and 21.35 s(-1)mM(-1), respectively, indicating that the MBs represent a positive contrast agent in T(1)-weighted images. In vivo MR imaging experiments on 18 rats showed that focused US combined with albumin-(Gd-DTPA) MBs can be used to both induce disruption of the BBB and detect ICH. To compare the signal intensity change between pure BBB opening and BBB opening accompanying ICH, albumin-(Gd-DTPA) MB imaging can provide a ratio of 5.14 with significant difference (p = 0.026), whereas Gd-DTPA imaging only provides a ratio of 2.13 and without significant difference (p = 0.108). The results indicate that albumin-(Gd-DTPA) MBs have potential as a US/MR dual-modality contrast agent for BBB opening and differentiating focused-US-induced BBB opening from ICH, and can monitor the focused ultrasound brain drug delivery process.

A statistical model describing combined irreversible electroporation and electroporation-induced blood-brain barrier disruption.

PubMed

Sharabi, Shirley; Kos, Bor; Last, David; Guez, David; Daniels, Dianne; Harnof, Sagi; Mardor, Yael; Miklavcic, Damijan

2016-03-01

Electroporation-based therapies such as electrochemotherapy (ECT) and irreversible electroporation (IRE) are emerging as promising tools for treatment of tumors. When applied to the brain, electroporation can also induce transient blood-brain-barrier (BBB) disruption in volumes extending beyond IRE, thus enabling efficient drug penetration. The main objective of this study was to develop a statistical model predicting cell death and BBB disruption induced by electroporation. This model can be used for individual treatment planning. Cell death and BBB disruption models were developed based on the Peleg-Fermi model in combination with numerical models of the electric field. The model calculates the electric field thresholds for cell kill and BBB disruption and describes the dependence on the number of treatment pulses. The model was validated using in vivo experimental data consisting of rats brains MRIs post electroporation treatments. Linear regression analysis confirmed that the model described the IRE and BBB disruption volumes as a function of treatment pulses number (r(2) = 0.79; p < 0.008, r(2) = 0.91; p < 0.001). The results presented a strong plateau effect as the pulse number increased. The ratio between complete cell death and no cell death thresholds was relatively narrow (between 0.88-0.91) even for small numbers of pulses and depended weakly on the number of pulses. For BBB disruption, the ratio increased with the number of pulses. BBB disruption radii were on average 67% ± 11% larger than IRE volumes. The statistical model can be used to describe the dependence of treatment-effects on the number of pulses independent of the experimental setup.

Pharmacodynamic and Therapeutic Investigation of Focused Ultrasound-Induced Blood-Brain Barrier Opening for Enhanced Temozolomide Delivery in Glioma Treatment

PubMed Central

Liu, Hao-Li; Huang, Chiung-Yin; Chen, Ju-Yu; Wang, Hay-Yan Jack; Chen, Pin-Yuan; Wei, Kuo-Chen

2014-01-01

Focused ultrasound (FUS) exposure with the presence of microbubbles has been shown to transiently open the blood-brain barrier (BBB), and thus has potential to enhance the delivery of various kinds of therapeutic agents into brain tumors. The purpose of this study was to assess the preclinical therapeutic efficacy of FUS-BBB opening for enhanced temozolomide (TMZ) delivery in glioma treatment. FUS exposure with microbubbles was delivered to open the BBB of nude mice that were either normal or implanted with U87 human glioma cells. Different TMZ dose regimens were tested, ranging from 2.5 to 25 mg/kg. Plasma and brain samples were obtained at different time-points ranging from 0.5 to 4 hours, and the TMZ concentration within samples was quantitated via a developed LC-MS/MS procedure. Tumor progression was followed with T2-MRI, and animal survival and brain tissue histology were conducted. Results demonstrated that FUS-BBB opening caused the local TMZ accumulation in the brain to increase from 6.98 to 19 ng/mg. TMZ degradation time in the tumor core was found to increase from 1.02 to 1.56 hours. Improved tumor progression and animal survival were found at different TMZ doses (up to 15% and 30%, respectively). In conclusion, this study provides preclinical evidence that FUS-BBB opening increases the local concentration of TMZ to improve the control of tumor progression and animal survival, suggesting the potential for clinical application to improve current brain tumor treatment. PMID:25490097

Facilitation of Drug Transport across the Blood-Brain Barrier with Ultrasound and Microbubbles.

PubMed

Meairs, Stephen

2015-08-31

Medical treatment options for central nervous system (CNS) diseases are limited due to the inability of most therapeutic agents to penetrate the blood-brain barrier (BBB). Although a variety of approaches have been investigated to open the BBB for facilitation of drug delivery, none has achieved clinical applicability. Mounting evidence suggests that ultrasound in combination with microbubbles might be useful for delivery of drugs to the brain through transient opening of the BBB. This technique offers a unique non-invasive avenue to deliver a wide range of drugs to the brain and promises to provide treatments for CNS disorders with the advantage of being able to target specific brain regions without unnecessary drug exposure. If this method could be applied for a range of different drugs, new CNS therapeutic strategies could emerge at an accelerated pace that is not currently possible in the field of drug discovery and development. This article reviews both the merits and potential risks of this new approach. It assesses methods used to verify disruption of the BBB with MRI and examines the results of studies aimed at elucidating the mechanisms of opening the BBB with ultrasound and microbubbles. Possible interactions of this novel delivery method with brain disease, as well as safety aspects of BBB disruption with ultrasound and microbubbles are addressed. Initial translational research for treatment of brain tumors and Alzheimer's disease is presented.

Ultrasound-mediated delivery and distribution of polymeric nanoparticles in the normal brain parenchyma of a metastatic brain tumour model

PubMed Central

Baghirov, Habib; Snipstad, Sofie; Sulheim, Einar; Berg, Sigrid; Hansen, Rune; Thorsen, Frits; Mørch, Yrr; Åslund, Andreas K. O.

2018-01-01

The treatment of brain diseases is hindered by the blood-brain barrier (BBB) preventing most drugs from entering the brain. Focused ultrasound (FUS) with microbubbles can open the BBB safely and reversibly. Systemic drug injection might induce toxicity, but encapsulation into nanoparticles reduces accumulation in normal tissue. Here we used a novel platform based on poly(2-ethyl-butyl cyanoacrylate) nanoparticle-stabilized microbubbles to permeabilize the BBB in a melanoma brain metastasis model. With a dual-frequency ultrasound transducer generating FUS at 1.1 MHz and 7.8 MHz, we opened the BBB using nanoparticle-microbubbles and low-frequency FUS, and applied high-frequency FUS to generate acoustic radiation force and push nanoparticles through the extracellular matrix. Using confocal microscopy and image analysis, we quantified nanoparticle extravasation and distribution in the brain parenchyma. We also evaluated haemorrhage, as well as the expression of P-glycoprotein, a key BBB component. FUS and microbubbles distributed nanoparticles in the brain parenchyma, and the distribution depended on the extent of BBB opening. The results from acoustic radiation force were not conclusive, but in a few animals some effect could be detected. P-glycoprotein was not significantly altered immediately after sonication. In summary, FUS with our nanoparticle-stabilized microbubbles can achieve accumulation and displacement of nanoparticles in the brain parenchyma. PMID:29338016

Opening of brain blood barrier induced by red light and central analgesic improvement of cobra neurotoxin.

PubMed

Ye, Yong; Li, Yue; Fang, Fei

2014-05-05

Cobra neurotoxin (NT) has central analgesic effects, but it is difficult to pass through brain blood barrier (BBB). A novel method of red light induction is designed to help NT across BBB, which is based on photosensitizer activation by red light to generate reactive oxygen species (ROS) to open BBB. The effects were evaluated on cell models and animals in vivo with illumination by semiconductor laser at 670nm on photosensitizer pheophorbide isolated from silkworm excrement. Brain microvascular endothelial cells and astrocytes were co-cultured to build up BBB cell model. The radioactivity of (125)I-NT was measured in cells and tissues for NT permeation. Three ways of cranial irradiation, nasal cavity and intravascular irradiation were tested with combined injection of (125)I-NT 20μg/kg and pheophorbide 100μg/kg to rats, and organs of rats were separated and determined the radioactivity. Paw pressure test in rats, hot plate and writhing test in mice were applied to appraise the analgesic effects. NT across BBB cell model increased with time of illumination, and reached stable level after 60min. So did ROS in cells. NT mainly distributed in liver and kidney of rats, significantly increased in brain after illumination, and improved analgesic effects. Excitation of pheophorbide at red light produces ROS to open BBB, help NT enter brain, and enhance its central action. This research provides a new method for drug across BBB to improve its central role. Copyright © 2014 Elsevier B.V. All rights reserved.

Nrf2 activator ameliorates hemorrhagic transformation in focal cerebral ischemia under warfarin anticoagulation.

PubMed

Imai, Takahiko; Takagi, Toshinori; Kitashoji, Akira; Yamauchi, Keita; Shimazawa, Masamitsu; Hara, Hideaki

2016-05-01

Oxidative stress has been reported to be a main cause of neuronal cell death in ischemia reperfusion injury (IRI). Nuclear factor-erythroid 2-related factor 2 (Nrf2) is an important factor involved in anti-oxidative responses. We previously reported that bardoxolone methyl (BARD), an Nrf2 activator, prevented damage induced by IRI. In this study, we investigated the effect of BARD on hemorrhagic transformation in the context of blood brain barrier (BBB) protection. Mice received pre-treatment with warfarin (4.0 mg/kg, p.o.). IRI was subsequently induced 18 h after the warfarin administration by transient middle cerebral artery occlusion (MCAO) for 6 h. BARD (0.06, 0.2, 0.6 or 2.0 mg/kg) or saline was injected intravenously immediately after reperfusion. The infarct volume, neurological score, intracranial hemorrhage volume, and BBB permeability were evaluated 24 h after MCAO. The survival rate and behavioral functional recovery were evaluated for 7 days following IRI. Furthermore, the effects of BARD on BBB components were investigated by western blotting and immunostaining analysis. BARD suppressed warfarin-mediated increases in the intracranial hemorrhage volume without affecting the infarct volume. BBB permeability was also suppressed by administration of BARD. Western blotting showed that BARD increased expression of BBB components such as endothelial cells, pericytes, and tight junction proteins. Furthermore, immunostaining showed that BARD induced localization of Nrf2 to endothelial cells and pericytes. BARD suppressed the exacerbation hemorrhage caused by warfarin pretreatment and ameliorated BBB disruption by protecting endothelial cells, pericytes, and tight junction protein expressions. These results indicate that Nrf2 activators may be an effective therapy against hemorrhagic transformation caused by anticoagulant drugs. Copyright © 2016 Elsevier Inc. All rights reserved.

A statistical model describing combined irreversible electroporation and electroporation-induced blood-brain barrier disruption

PubMed Central

Sharabi, Shirley; Kos, Bor; Last, David; Guez, David; Daniels, Dianne; Harnof, Sagi; Miklavcic, Damijan

2016-01-01

Background Electroporation-based therapies such as electrochemotherapy (ECT) and irreversible electroporation (IRE) are emerging as promising tools for treatment of tumors. When applied to the brain, electroporation can also induce transient blood-brain-barrier (BBB) disruption in volumes extending beyond IRE, thus enabling efficient drug penetration. The main objective of this study was to develop a statistical model predicting cell death and BBB disruption induced by electroporation. This model can be used for individual treatment planning. Material and methods Cell death and BBB disruption models were developed based on the Peleg-Fermi model in combination with numerical models of the electric field. The model calculates the electric field thresholds for cell kill and BBB disruption and describes the dependence on the number of treatment pulses. The model was validated using in vivo experimental data consisting of rats brains MRIs post electroporation treatments. Results Linear regression analysis confirmed that the model described the IRE and BBB disruption volumes as a function of treatment pulses number (r2 = 0.79; p < 0.008, r2 = 0.91; p < 0.001). The results presented a strong plateau effect as the pulse number increased. The ratio between complete cell death and no cell death thresholds was relatively narrow (between 0.88-0.91) even for small numbers of pulses and depended weakly on the number of pulses. For BBB disruption, the ratio increased with the number of pulses. BBB disruption radii were on average 67% ± 11% larger than IRE volumes. Conclusions The statistical model can be used to describe the dependence of treatment-effects on the number of pulses independent of the experimental setup. PMID:27069447

Low-Pressure Burst-Mode Focused Ultrasound Wave Reconstruction and Mapping for Blood-Brain Barrier Opening: A Preclinical Examination

PubMed Central

Xia, Jingjing; Tsui, Po-Hsiang; Liu, Hao-Li

2016-01-01

Burst-mode focused ultrasound (FUS) exposure has been shown to induce transient blood-brain barrier (BBB) opening for potential CNS drug delivery. FUS-BBB opening requires imaging guidance during the intervention, yet current imaging technology only enables postoperative outcome confirmation. In this study, we propose an approach to visualize short-burst low-pressure focal beam distribution that allows to be applied in FUS-BBB opening intervention on small animals. A backscattered acoustic-wave reconstruction method based on synchronization among focused ultrasound emission, diagnostic ultrasound receiving and passively beamformed processing were developed. We observed that focal beam could be successfully visualized for in vitro FUS exposure with 0.5–2 MHz without involvement of microbubbles. The detectable level of FUS exposure was 0.467 MPa in pressure and 0.05 ms in burst length. The signal intensity (SI) of the reconstructions was linearly correlated with the FUS exposure level both in-vitro (r2 = 0.9878) and in-vivo (r2 = 0.9943), and SI level of the reconstructed focal beam also correlated with the success and level of BBB-opening. The proposed approach provides a feasible way to perform real-time and closed-loop control of FUS-based brain drug delivery. PMID:27295608

Low-Pressure Burst-Mode Focused Ultrasound Wave Reconstruction and Mapping for Blood-Brain Barrier Opening: A Preclinical Examination

NASA Astrophysics Data System (ADS)

Xia, Jingjing; Tsui, Po-Hsiang; Liu, Hao-Li

2016-06-01

Burst-mode focused ultrasound (FUS) exposure has been shown to induce transient blood-brain barrier (BBB) opening for potential CNS drug delivery. FUS-BBB opening requires imaging guidance during the intervention, yet current imaging technology only enables postoperative outcome confirmation. In this study, we propose an approach to visualize short-burst low-pressure focal beam distribution that allows to be applied in FUS-BBB opening intervention on small animals. A backscattered acoustic-wave reconstruction method based on synchronization among focused ultrasound emission, diagnostic ultrasound receiving and passively beamformed processing were developed. We observed that focal beam could be successfully visualized for in vitro FUS exposure with 0.5-2 MHz without involvement of microbubbles. The detectable level of FUS exposure was 0.467 MPa in pressure and 0.05 ms in burst length. The signal intensity (SI) of the reconstructions was linearly correlated with the FUS exposure level both in-vitro (r2 = 0.9878) and in-vivo (r2 = 0.9943), and SI level of the reconstructed focal beam also correlated with the success and level of BBB-opening. The proposed approach provides a feasible way to perform real-time and closed-loop control of FUS-based brain drug delivery.

Focused ultrasound-mediated bbb disruption is associated with an increase in activation of AKT: experimental study in rats

PubMed Central

2010-01-01

Background The Blood Brain Barrier (BBB) maintains the homeostasis of central nervous system by preventing the free passage of macromolecules from the systemic circulation into the brain. This normal physiological function of the BBB presents a challenge for delivery of therapeutic compounds into the brain. Recent studies have shown that the application of focused ultrasound together with ultrasound contrast agent (microbubbles) temporarily increases the permeability of the BBB. This effect is associated with breakdown of tight junctions, the structures that regulate the paracellular permeability of the endothelial cell layer. The influence of this ultrasound effect on the activation of intracellular signaling proteins is currently not well understood. Therefore, the aim of this study was to investigate the activation of cell survival signaling molecules in response to ultrasound-mediated BBB opening; Methods The BBB was disrupted in two four-spot lines (1-1.5 mm spacing) along the right hemisphere of rat brain with ultrasound beams (0.3 MPa, 120 s, 10 ms bursts, repetition frequency = 1 Hz) in the presence Definity microbubbles. Contrast-enhanced MRI images were acquired to assess the extent of BBB opening upon which the animals were sacrificed and the brains removed and processed for biochemical and immunohistochemical analyses; Results Immunoblotting of sonicated brain lysates resolved by SDS-PAGE demonstrated an increase in phosphorylation of Akt and its downstream signaling molecule, GSK3β, while the phosphorylation of MAPK remained unchanged. The elevated levels of pAkt and pGSK3β are still evident after 24 hours post-sonication, a time point where the integrity of the BBB is known to be re-established. Furthermore, immunofluoresence staining localized this increase in pAkt and pGSK3β levels to neuronal cells flanking the region of the disrupted BBB; Conclusions Our data demonstrates that ultrasound-mediated BBB disruption causes an activation of the Akt signaling pathway in neuronal cells surrounding the disrupted BBB. PMID:21078165

The interaction between the meningeal lymphatics and blood-brain barrier

NASA Astrophysics Data System (ADS)

Semyachkina-Glushkovskaya, O.; Abdurashitov, A.; Dubrovsky, A.; Pavlov, A.; Shushunova, N.; Maslyakova, G.; Navolokin, N.; Bucharskaya, A.; Tuchin, V.; Kurths, J.

2018-02-01

Here we show the interaction between the meningeal lymphatic system and the blood-brain barrier (BBB) function. In normal state, the meningeal lymphatic vessels are invisible on optical coherent tomography (OCT), while during the opening of the BBB, meningeal lymphatic vessels are clearly visualized by OCT in the area of cerebral venous sinuses. These results give a significant impulse in the new application of OCT for the study of physiology of meningeal lymphatic system as well as sheds light on novel strategies in the prognosis of the opening of the BBB related with many central nervous system diseases, such as stroke, brain trauma, Alzheimers disease, etc.

Effect of Synthetic Matrix Metalloproteinase Inhibitors on Lipopolysaccharide-Induced Blood-Brain Barrier Opening in Rodents: Differences in Response Based on Strains and Solvents

PubMed Central

Rosenberg, Gary A.; Estrada, Eduardo Y.; Mobashery, Shahriar

2007-01-01

Matrix metalloproteinase inhibitors (MMPIs) reduce blood-brain barrier (BBB) disruption and prevent cell death. Animal models of multiple sclerosis, cerebral ischemia and hemorrhage, and bacterial meningitis respond to treatment with MMPIs. We have used the intracerebral injection of lipopolysaccharide (LPS) in rat, which induces MMP production and results in a delayed opening of the BBB, to screen MMPIs to identify therapeutic agents. We hypothesized that the mouse would respond similarly to LPS and that the mouse/LPS model of BBB damage would be more useful for screening of MMPIs. Therefore, we adapted the rat LPS model to the mouse and compared the response to LPS and treatment with MMPIs. Wistar-Kyoto rats (WKY) and three strains of mice had stereotactic injections of LPS into the caudate. 14C-sucrose was used to measure permeability of the BBB 24 hours after injection. Initially, we tested three broad-spectrum MMPIs in the rat, BB-1101, BB-94, and BB-2293, and a MMP-2 selective inhibitor, IW449; both BB-1101 and BB-94 significantly suppressed LPS-induced BBB damage (p<0.05). In the 3 mouse strains, C57/BL6, C57/BL10, and C57/BL10HIIIR2, LPS significantly opened the BBB in C57/BL6, and it was the only strain that showed a reduction in BBB permeability with BB-94. Treatment with methylprednisolone and several broad spectrum MMPIs, including BB-1101, were ineffective in the C57/BL6. There was a significant reduction in BBB permeability seen with 10% dimethyl sulfoxide (DMSO) alone, which was used to dissolve the selective MMP-2 and -9 inhibitor, SB-3CT. The tetracycline derivative, minocycline, reduced the BBB injury in mouse by blocking the production of MMP-9. Our results show variability in rats and mice to LPS and MMPIs, which most likely is based on genetic make-up. Understanding these differences may provide important clues that could guide selection of MMPIs in treatment of neurological diseases. PMID:17184743

Magnetic Resonance Imaging Profile of Blood–Brain Barrier Injury in Patients With Acute Intracerebral Hemorrhage

PubMed Central

Aksoy, Didem; Bammer, Roland; Mlynash, Michael; Venkatasubramanian, Chitra; Eyngorn, Irina; Snider, Ryan W.; Gupta, Sandeep N.; Narayana, Rashmi; Fischbein, Nancy; Wijman, Christine A. C.

2013-01-01

Background Spontaneous intracerebral hemorrhage (ICH) is associated with blood–brain barrier (BBB) injury, which is a poorly understood factor in ICH pathogenesis, potentially contributing to edema formation and perihematomal tissue injury. We aimed to assess and quantify BBB permeability following human spontaneous ICH using dynamic contrast‐enhanced magnetic resonance imaging (DCE MRI). We also investigated whether hematoma size or location affected the amount of BBB leakage. Methods and Results Twenty‐five prospectively enrolled patients from the Diagnostic Accuracy of MRI in Spontaneous intracerebral Hemorrhage (DASH) study were examined using DCE MRI at 1 week after symptom onset. Contrast agent dynamics in the brain tissue and general tracer kinetic modeling were used to estimate the forward leakage rate (Ktrans) in regions of interest (ROI) in and surrounding the hematoma and in contralateral mirror–image locations (control ROI). In all patients BBB permeability was significantly increased in the brain tissue immediately adjacent to the hematoma, that is, the hematoma rim, compared to the contralateral mirror ROI (P<0.0001). Large hematomas (>30 mL) had higher Ktrans values than small hematomas (P<0.005). Ktrans values of lobar hemorrhages were significantly higher than the Ktrans values of deep hemorrhages (P<0.005), independent of hematoma volume. Higher Ktrans values were associated with larger edema volumes. Conclusions BBB leakage in the brain tissue immediately bordering the hematoma can be measured and quantified by DCE MRI in human ICH. BBB leakage at 1 week is greater in larger hematomas as well as in hematomas in lobar locations and is associated with larger edema volumes. PMID:23709564

Targeted drug delivery with focused ultrasound-induced blood-brain barrier opening using acoustically-activated nanodroplets.

PubMed

Chen, Cherry C; Sheeran, Paul S; Wu, Shih-Ying; Olumolade, Oluyemi O; Dayton, Paul A; Konofagou, Elisa E

2013-12-28

Focused ultrasound (FUS) in the presence of systemically administered microbubbles has been shown to locally, transiently and reversibly increase the permeability of the blood-brain barrier (BBB), thus allowing targeted delivery of therapeutic agents in the brain for the treatment of central nervous system diseases. Currently, microbubbles are the only agents that have been used to facilitate the FUS-induced BBB opening. However, they are constrained within the intravascular space due to their micron-size diameters, limiting the delivery effect at or near the microvessels. In the present study, acoustically-activated nanodroplets were used as a new class of contrast agents to mediate FUS-induced BBB opening in order to study the feasibility of utilizing these nanoscale phase-shift particles for targeted drug delivery in the brain. Significant dextran delivery was achieved in the mouse hippocampus using nanodroplets at clinically relevant pressures. Passive cavitation detection was used in the attempt to establish a correlation between the amount of dextran delivered in the brain and the acoustic emission recorded during sonication. Conventional microbubbles with the same lipid shell composition and perfluorobutane core as the nanodroplets were also used to compare the efficiency of an FUS-induced dextran delivery. It was found that nanodroplets had a higher BBB opening pressure threshold but a lower stable cavitation threshold than microbubbles, suggesting that contrast agent-dependent acoustic emission monitoring was needed. A more homogeneous dextran delivery within the targeted hippocampus was achieved using nanodroplets without inducing inertial cavitation or compromising safety. Our results offered a new means of developing the FUS-induced BBB opening technology for potential extravascular targeted drug delivery in the brain, extending the potential drug delivery region beyond the cerebral vasculature. © 2013.

Effects of agmatine on blood-brain barrier stabilization assessed by permeability MRI in a rat model of transient cerebral ischemia.

PubMed

Ahn, S S; Kim, S H; Lee, J E; Ahn, K J; Kim, D J; Choi, H S; Kim, J; Shin, N-Y; Lee, S-K

2015-02-01

BBB disruption after acute ischemic stroke and subsequent permeability increase may be enhanced by reperfusion. Agmatine has been reported to attenuate BBB disruption. Our aim was to evaluate the effects of agmatine on BBB stabilization in a rat model of transient cerebral ischemia by using permeability dynamic contrast-enhanced MR imaging at early stages and subsequently to demonstrate the feasibility of dynamic contrast-enhanced MR imaging for the investigation of new therapies. Thirty-four male Sprague-Dawley rats were subjected to transient MCA occlusion for 90 minutes. Immediately after reperfusion, agmatine (100 mg/kg) or normal saline was injected intraperitoneally into the agmatine-treated group (n = 17) or the control group, respectively. MR imaging was performed after reperfusion. For quantitative analysis, regions of interest were defined within the infarct area, and values for volume transfer constant, rate transfer coefficient, volume fraction of extravascular extracellular space, and volume fraction of blood plasma were obtained. Infarct volume, infarct growth, quantitative imaging parameters, and numbers of factor VIII-positive cells after immunohistochemical staining were compared between control and agmatine-treated groups. Among the permeability parameters, volume transfer constant and volume fraction of extravascular extracellular space were significantly lower in the agmatine-treated group compared with the control group (0.05 ± 0.02 minutes(-1) versus 0.08 ± 0.03 minute(-1), P = .012, for volume transfer constant and 0.12 ± 0.06 versus 0.22 ± 0.15, P = .02 for volume fraction of extravascular extracellular space). Other permeability parameters were not significantly different between the groups. The number of factor VIII-positive cells was less in the agmatine-treated group than in the control group (3-fold versus 4-fold, P = .037). In ischemic stroke, agmatine protects the BBB, which can be monitored in vivo by quantification of permeability by using dynamic contrast-enhanced MR imaging. Therefore, dynamic contrast-enhanced MR imaging may serve as a potential imaging biomarker for assessing the BBB stabilization properties of pharmacologic agents. © 2015 by American Journal of Neuroradiology.

Unilateral Opening of Rat Blood-Brain Barrier Assisted by Diagnostic Ultrasound Targeted Microbubbles Destruction.

PubMed

Xu, Yali; Cui, Hai; Zhu, Qiong; Hua, Xing; Xia, Hongmei; Tan, Kaibin; Gao, Yunhua; Zhao, Jing; Liu, Zheng

2016-01-01

Objective. Blood-brain barrier (BBB) is a key obstacle that prevents the medication from blood to the brain. Microbubble-enhanced cavitation by focused ultrasound can open the BBB and proves to be valuable in the brain drug delivery. The study aimed to explore the feasibility, efficacy, and safety of unilateral opening of BBB using diagnostic ultrasound targeted microbubbles destruction in rats. Methods. A transtemporal bone irradiation of diagnostic ultrasound and intravenous injection of lipid-coated microbubbles were performed at unilateral hemisphere. Pathological changes were monitored. Evans Blue extravasation grades, extraction from brain tissue, and fluorescence optical density were quantified. Lanthanum nitrate was traced by transmission electron microscopy. Results. After diagnostic ultrasound mediated microbubbles destruction, Evans Blue extravasation and fluorescence integrated optical density were significantly higher in the irradiated hemisphere than the contralateral side (all p < 0.01). Erythrocytes extravasations were demonstrated in the ultrasound-exposed hemisphere (4 ± 1, grade 2) while being invisible in the control side. Lanthanum nitrate tracers leaked through interendothelial cleft and spread to the nerve fiber existed in the irradiation side. Conclusions. Transtemporal bone irradiation under DUS mediated microbubble destruction provides us with a more accessible, safer, and higher selective BBB opening approach in rats, which is advantageous in brain targeted drugs delivery.

A NASTRAN Vibration Model of the AH-1G Helicopter Airframe. Volume 1

DTIC Science & Technology

1974-06-01

Bulkhead .012 ZZ 1863343 Bulkhead .012 AAA 1863345 Bulkhead .012 j EBB 1863546 Bulkhead .012 j ccc 1863746 Bulkhead .012 \\ ODD 1863748...123 12) 123 RULE AAA AAA AAA AAA BBB EBB AAA AAA AAA AAA BBB BBB OMIT D.O.F. 456 456 123 123 123 123 123 123 123 123 RULE...load in the member Increases. The program determines the section properties, unsytnmetrical bending stresses, element loads and shear flows for a

Hydrophilic solute transport across the rat blood-brain barrier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lucchesi, K.J.

1987-01-01

Brain capillary permeability-surface area products (PS) of hydrophilic solutes ranging in size from 180 to 5,500 Daltons were measured in rats according to the method of Ohno, Pettigrew and Rapoport. The distribution volume of 70 KD dextran at 10 minutes after i.v. injection was also measured to determine the residual volume of blood in brain tissue at the time of sacrifice. Small test solutes were injected in pairs in order to elucidate whether their transfer into the brain proceeds by diffusion through water- or lipid-filled channels or by vesicular transport. This issue was examined in rats whose blood-brain barrier (BBB)more » was presumed to be intact (untreated) and in rats that received intracarotid infusions to open the BBB (isosmotic salt (ISS) and hyperosmolar arabinose). Ohno PS values of {sup 3}H-inulin and {sup 14}C-L-glucose in untreated rats were found to decrease as the labelling time was lengthened. This was evidence that a rapidly equilibrating compartment exists between blood and brain that renders the Ohno two-compartment model inadequate for computing true transfer rate constants. When the data were reanalyzed using a multi-compartment graphical analysis, solutes with different molecular radii were found to enter the brain at approximately equal rates. Furthermore, unidirectional transport is likely to be initiated by solute adsorption to a glycocalyx coat on the luminal surface of brain capillary endothelium. Apparently, more inulin than L-glucose was adsorbed, which may account for its slightly faster transfer across the BBB. After rats were treated with intracarotid infusions of ISS or hyperosmolar arabinose, solute PS values were significantly increased, but the ratio of PS for each of the solute pairs approached that of their free-diffusion coefficients.« less

Overexpression of caveolin-1 attenuates brain edema by inhibiting tight junction degradation.

PubMed

Choi, Kang-Ho; Kim, Hyung-Seok; Park, Man-Seok; Lee, Eun-Bin; Lee, Jung-Kil; Kim, Joon-Tae; Kim, Ja-Hae; Lee, Min-Cheol; Lee, Hong-Joon; Cho, Ki-Hyun

2016-10-18

Cerebral edema from the disruption of the blood-brain barrier (BBB) after cerebral ischemia is a major cause of morbidity and mortality as well as a common event in patients with stroke. Caveolins (Cavs) are thought to regulate BBB functions. Here, we report for the first time that Cav-1 overexpression (OE) decreased brain edema from BBB disruption following ischemic insult. Edema volumes and Cav-1 expression levels were measured following photothrombosis and middle cerebral artery occlusion (MCAO). Endothelial cells that were transduced with a Cav-1 lentiviral expression vector were transplanted into rats. BBB permeability was quantified with Evans blue extravasation. Edema volume was determined from measures of the extravasation area, brain water content, and average fluorescence intensity after Cy5.5 injections. Tight junction (TJ) protein expression was measured with immunoblotting. Cav-1 expression levels and vasogenic brain edema correlated strongly after ischemic insult. Cav-1 expression and BBB disruption peaked 3 d after the MCAO. In addition, intravenous administration of endothelial cells expressing Cav-1 effectively increased the Cav-1 levels 3 d after the MCAO ischemic insult. Importantly, Cav-1 OE ameliorated the vasogenic edema by inhibiting the degradation of TJ protein expression in the acute phase of ischemic stroke. These results suggested that Cav-1 OE protected the integrity of the BBB mainly by preventing the degradation of TJ proteins in rats. These findings need to be confirmed in a clinical setting in human subjects.

MRI and quantitative autoradiographic studies following bolus injections of unlabeled and 14C-labeled gadolinium-diethylenetriamine-pentaacetic acid in a rat model of stroke yield similar distribution volumes and blood-to-brain influx rate constants

PubMed Central

Nagaraja, Tavarekere N.; Ewing, James R.; Karki, Kishor; Jacobs, Paul E.; Divine, George W.; Fenstermacher, Joseph D.; Patlak, Clifford S.; Knight, Robert A.

2012-01-01

In previous studies on a rat model of transient cerebral ischemia, the blood and brain concentrations of gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) following intravenous bolus injection were repeatedly assessed by dynamic contrast-enhanced (DCE)-MRI, and blood-to-brain influx rate constants (Ki) were calculated from Patlak plots of the data in areas with blood–brain barrier (BBB) opening. For concurrent validation of these findings, after completing the DCE-MRI study, radiolabeled sucrose or α-aminoisobutyric acid was injected intravenously, and the brain disposition and Ki values were calculated by quantitative autoradiography (QAR) assay employing the single-time equation. To overcome two of the shortcomings of this comparison, the present experiments were carried out with a radiotracer virtually identical to Gd-DTPA, Gd-[14C]DTPA, and Ki was calculated from both sets of data by the single-time equation. The protocol included 3 h of middle cerebral artery occlusion and 2.5 h of reperfusion in male Wistar rats (n = 15) preceding the DCE-MRI Gd-DTPA and QAR Gd-[14C]DTPA measurements. In addition to Ki, the tissue-to-blood concentration ratios, or volumes of distribution (VR), were calculated. The regions of BBB opening were similar on the MRI maps and autoradiograms. Within them, VR was nearly identical for Gd-DTPA and Gd-[14C]DTPA, and Ki was slightly, but not significantly, higher for Gd-DTPA than for Gd-[14C]DTPA. The Ki values were well correlated (r = 0.67; p = 0.001). When the arterial concentration–time curve of Gd-DTPA was adjusted to match that of Gd-[14C]DTPA, the two sets of Ki values were equal and statistically comparable with those obtained previously by Patlak plots (the preferred, less model-dependent, approach) of the same data (p = 0.2–0.5). These findings demonstrate that this DCE-MRI technique accurately measures the Gd-DTPA concentration in blood and brain, and that Ki estimates based on such data are good quantitative indicators of BBB injury. PMID:21674656

Wnt/β-catenin signaling controls development of the blood–brain barrier

PubMed Central

Liebner, Stefan; Corada, Monica; Bangsow, Thorsten; Babbage, Jane; Taddei, Andrea; Czupalla, Cathrin J.; Reis, Marco; Felici, Angelina; Wolburg, Hartwig; Fruttiger, Marcus; Taketo, Makoto M.; von Melchner, Harald; Plate, Karl Heinz; Gerhardt, Holger; Dejana, Elisabetta

2008-01-01

The blood–brain barrier (BBB) is confined to the endothelium of brain capillaries and is indispensable for fluid homeostasis and neuronal function. In this study, we show that endothelial Wnt/β-catenin (β-cat) signaling regulates induction and maintenance of BBB characteristics during embryonic and postnatal development. Endothelial specific stabilization of β-cat in vivo enhances barrier maturation, whereas inactivation of β-cat causes significant down-regulation of claudin3 (Cldn3), up-regulation of plamalemma vesicle-associated protein, and BBB breakdown. Stabilization of β-cat in primary brain endothelial cells (ECs) in vitro by N-terminal truncation or Wnt3a treatment increases Cldn3 expression, BBB-type tight junction formation, and a BBB characteristic gene signature. Loss of β-cat or inhibition of its signaling abrogates this effect. Furthermore, stabilization of β-cat also increased Cldn3 and barrier properties in nonbrain-derived ECs. These findings may open new therapeutic avenues to modulate endothelial barrier function and to limit the devastating effects of BBB breakdown. PMID:18955553

Dynamic monitoring of blood-brain barrier integrity using water exchange index (WEI) during mannitol and CO2 challenges in mouse brain.

PubMed

Huang, Shuning; Farrar, Christian T; Dai, Guangping; Kwon, Seon Joo; Bogdanov, Alexei A; Rosen, Bruce R; Kim, Young R

2013-04-01

The integrity of the blood-brain barrier (BBB) is critical to normal brain function. Traditional techniques for the assessment of BBB disruption rely heavily on the spatiotemporal analysis of extravasating contrast agents. However, such methods based on the leakage of relatively large molecules are not suitable for the detection of subtle BBB impairment or for the performance of repeated measurements in a short time frame. Quantification of the water exchange rate constant (WER) across the BBB using strictly intravascular contrast agents could provide a much more sensitive method for the quantification of the BBB integrity. To estimate WER, we have recently devised a powerful new method using a water exchange index (WEI) biomarker and demonstrated BBB disruption in an acute stroke model. Here, we confirm that WEI is sensitive to even very subtle changes in the integrity of the BBB caused by: (i) systemic hypercapnia and (ii) low doses of a hyperosmolar solution. In addition, we have examined the sensitivity and accuracy of WEI as a biomarker of WER using computer simulation. In particular, the dependence of the WEI-WER relation on changes in vascular blood volume, T1 relaxation of cellular magnetization and transcytolemmal water exchange was explored. Simulated WEI was found to vary linearly with WER for typically encountered exchange rate constants (1-4 Hz), regardless of the blood volume. However, for very high WER (>5 Hz), WEI became progressively more insensitive to increasing WER. The incorporation of transcytolemmal water exchange, using a three-compartment tissue model, helped to extend the linear WEI regime to slightly higher WER, but had no significant effect for most physiologically important WERs (WER < 4 Hz). Variation in cellular T1 had no effect on WEI. Using both theoretical and experimental approaches, our study validates the utility of the WEI biomarker for the monitoring of BBB integrity. Copyright © 2012 John Wiley & Sons, Ltd.

Dynamic Monitoring of Blood-Brain Barrier Integrity using Water Exchange Index (WEI) During Mannitol and CO2 Challenges in Mouse Brain

PubMed Central

Huang, Shuning; Farrar, Christian T.; Dai, Guangping; Kwon, Seon Joo; Bogdanov, Alexei A.; Rosen, Bruce R.; Kim, Young R.

2012-01-01

The integrity of the blood-brain barrier (BBB) is critical to normal brain function. Traditional techniques for assessing BBB disruption rely heavily on the spatiotemporal analysis of extravasating contrast agents. But such methods based on the leakage of relatively large molecules are not suitable to detect subtle BBB impairment or to perform repeated measurements in a short time frame. Quantification of the water exchange rate constant (WER) across the BBB using strictly intravascular contrast agents could provide a much more sensitive method for quantifying the BBB integrity. For estimating the WER, we have recently devised a powerful new method using a water exchange index (WEI) biomarker and demonstrated BBB disruption in an acute stroke model. Here we confirm that the WEI is sensitive to even very subtle changes in the integrity of the BBB caused by (1) systemic hypercapnia and (2) low doses of a hyperosmolar solution. In addition, we have examined the sensitivity and accuracy of the WEI as a biomarker of the WER using computer simulation. In particular, the dependence of the WEI-WER relation on changes in vascular blood volume, T1 relaxation of cellular magnetization, and transcytolemmal water exchange was explored. The simulated WEI was found to vary linearly with the WER for typically encountered exchange rate constants (1–4 Hz) regardless of the blood volume. However, for very high WER (>5 Hz) the WEI became progressively more insensitive to increasing WER. The incorporation of transcytolemmal water exchange, using a three-compartment tissue model, helped to extend the linear WEI regime to slightly higher WER, but had no significant effect for most physiologically important water exchange rate constants (WER<4 Hz). Variation in the cellular T1 had no effect on the WEI. Using both theoretical and experimental approaches, our study validates the utility of the WEI biomarker for monitoring BBB integrity. PMID:23055278

In-vivo imaging of blood-brain barrier permeability using positron emission tomography with 2-amino-[3-11C]isobutyric acid.

PubMed

Okada, Maki; Kikuchi, Tatsuya; Okamura, Toshimitsu; Ikoma, Yoko; Tsuji, Atsushi B; Wakizaka, Hidekatsu; Kamakura, Tomoo; Aoki, Ichio; Zhang, Ming-Rong; Kato, Koichi

2015-12-01

The blood-brain barrier (BBB) limits the entry of some therapeutics into the brain, resulting in reduced efficacy. BBB-opening techniques have been developed to enhance the entry into the brain. However, a noninvasive, highly sensitive and quantitative method for evaluating the changes in BBB permeability induced by such techniques is needed to optimize treatment protocols. We evaluated 2-amino-[3-C]isobutyric acid ([3-C]AIB) as a PET probe to quantify BBB permeability in model rats. BBB opening was induced by a lipopolysaccharide injection or focused ultrasound (FUS) sonication. [3-C]AIB distribution in the brain was evaluated by autoradiography and PET and compared with that of Evans blue, a traditional BBB permeability marker. Kinetics of [3-C]AIB was compared with that of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced MRI. The unidirectional blood-brain transfer constant (Ki) of [3-C]AIB was estimated using the Patlak plot. [3-C]AIB uptake in the lesion area was significantly higher than that in the control area and radioactivity colocalized with Evans blue in both models. [3-C]AIB uptake in the FUS-sonicated region decreased over time after sonication. The ratio of [3-C]AIB accumulation in the FUS-treated to the contralateral side increased during the experimental period, whereas that of the Gd-DTPA intensity reached a maximum at 10 min after injection and decreased thereafter. The [3-C]AIB Ki values were significantly higher in the lesion area than the control area. [3-C]AIB PET is a promising, highly sensitive and quantitative imaging method for assessment of BBB permeability.

Surfactants, not size or zeta-potential influence blood-brain barrier passage of polymeric nanoparticles.

PubMed

Voigt, Nadine; Henrich-Noack, Petra; Kockentiedt, Sarah; Hintz, Werner; Tomas, Jürgen; Sabel, Bernhard A

2014-05-01

Nanoparticles (NP) can deliver drugs across the blood-brain barrier (BBB), but little is known which of the factors surfactant, size and zeta-potential are essential for allowing BBB passage. To this end we designed purpose-built fluorescent polybutylcyanoacrylate (PBCA) NP and imaged the NP's passage over the blood-retina barrier - which is a model of the BBB - in live animals. Rats received intravenous injections of fluorescent PBCA-NP fabricated by mini-emulsion polymerisation to obtain various NP's compositions that varied in surfactants (non-ionic, anionic, cationic), size (67-464nm) and zeta-potential. Real-time imaging of retinal blood vessels and retinal tissue was carried out with in vivo confocal neuroimaging (ICON) before, during and after NP's injection. Successful BBB passage with subsequent cellular labelling was achieved if NP were fabricated with non-ionic surfactants or cationic stabilizers but not when anionic compounds were added. NP's size and charge had no influence on BBB passage and cell labelling. This transport was not caused by an unspecific opening of the BBB because control experiments with injections of unlabelled NP and fluorescent dye (to test a "door-opener" effect) did not lead to parenchymal labelling. Thus, neither NP's size nor chemo-electric charge, but particle surface is the key factor determining BBB passage. This result has important implications for NP engineering in medicine: depending on the surfactant, NP can serve one of two opposite functions: while non-ionic tensides enhance brain up-take, addition of anionic tensides prevents it. NP can now be designed to specifically enhance drug delivery to the brain or, alternatively, to prevent brain penetration so to reduce unwanted psychoactive effects of drugs or prevent environmental nanoparticles from entering tissue of the central nervous system. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthetic gelatinases inhibitor attenuates electromagnetic pulse-induced blood-brain barrier disruption by inhibiting gelatinases-mediated ZO-1 degradation in rats.

PubMed

Qiu, Lian-Bo; Zhou, Yan; Wang, Qi; Yang, Long-Long; Liu, Hai-Qiang; Xu, Sheng-Long; Qi, Yu-Hong; Ding, Gui-Rong; Guo, Guo-Zhen

2011-07-11

Previously we found that exposure to electromagnetic pulse (EMP) induced an increase in blood-brain-barrier (BBB) permeability and the degradation of tight junction protein ZO-1 in rats. Matrix metalloproteinases (MMPs), in particular gelatinases (MMP-2 and MMP-9), play a key role in degradation of tight junction proteins, are known mediators of BBB compromise. We hypothesized that the degradation of ZO-1 by gelatinases contributed to EMP-induced BBB opening. To test this hypothesis, the mRNA level of ZO-1, protein levels of MMP-2, MMP-9 and tissue inhibitor of metalloproteinases (TIMP-1 and TIMP-2) were detected in rat cerebral cortex after exposing rats to EMP at 200 kV/m for 200 pulses. It was found that the mRNA level of ZO-1 was unaltered at different time points after EMP exposure. The protein levels of MMP-2 and MMP-9 significantly increased at 3 h and 0.5 h, respectively. However, TIMP-1 (inhibitor of MMP-9) and TIMP-2 (inhibitor of MMP-2) only moderately increased after EMP exposure. In addition, in situ zymography results showed that the gelatinase activity increased in cerebral microvessels at 3 h after EMP exposure. When rats were treated with gelatinases inhibitor (SB-3CT) before EMP exposure, the EMP-induced BBB opening was attenuated and the ZO-1 degradation was reversed. Our results suggested that EMP-induced BBB opening was related to gelatinase mediated ZO-1 degradation. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Selective Limbic Blood–Brain Barrier Breakdown in a Feline Model of Limbic Encephalitis with LGI1 Antibodies

PubMed Central

Tröscher, Anna R.; Klang, Andrea; French, Maria; Quemada-Garrido, Lucía; Kneissl, Sibylle Maria; Bien, Christian G.; Pákozdy, Ákos; Bauer, Jan

2017-01-01

Human leucine-rich glioma-inactivated protein 1 encephalitis (LGI1) is an autoimmune limbic encephalitis in which serum and cerebrospinal fluid contain antibodies targeting LGI1, a protein of the voltage gated potassium channel (VGKC) complex. Recently, we showed that a feline model of limbic encephalitis with LGI1 antibodies, called feline complex partial seizures with orofacial involvement (FEPSO), is highly comparable to human LGI1 encephalitis. In human LGI1 encephalitis, neuropathological investigations are difficult because very little material is available. Taking advantage of this natural animal model to study pathological mechanisms will, therefore, contribute to a better understanding of its human counterpart. Here, we present a brain-wide histopathological analysis of FEPSO. We discovered that blood–brain barrier (BBB) leakage was present not only in all regions of the hippocampus but also in other limbic structures such as the subiculum, amygdale, and piriform lobe. However, in other regions, such as the cerebellum, no leakage was observed. In addition, this brain-region-specific immunoglobulin leakage was associated with the breakdown of endothelial tight junctions. Brain areas affected by BBB dysfunction also revealed immunoglobulin and complement deposition as well as neuronal cell death. These neuropathological findings were supported by magnetic resonance imaging showing signal and volume increase in the amygdala and the piriform lobe. Importantly, we could show that BBB disturbance in LGI1 encephalitis does not depend on T cell infiltrates, which were present brain-wide. This finding points toward another, so far unknown, mechanism of opening the BBB. The limbic predilection sites of immunoglobulin antibody leakage into the brain may explain why most patients with LGI1 antibodies have a limbic phenotype even though LGI1, the target protein, is ubiquitously distributed across the central nervous system. PMID:29093718

Selective Limbic Blood-Brain Barrier Breakdown in a Feline Model of Limbic Encephalitis with LGI1 Antibodies.

PubMed

Tröscher, Anna R; Klang, Andrea; French, Maria; Quemada-Garrido, Lucía; Kneissl, Sibylle Maria; Bien, Christian G; Pákozdy, Ákos; Bauer, Jan

2017-01-01

Human leucine-rich glioma-inactivated protein 1 encephalitis (LGI1) is an autoimmune limbic encephalitis in which serum and cerebrospinal fluid contain antibodies targeting LGI1, a protein of the voltage gated potassium channel (VGKC) complex. Recently, we showed that a feline model of limbic encephalitis with LGI1 antibodies, called feline complex partial seizures with orofacial involvement (FEPSO), is highly comparable to human LGI1 encephalitis. In human LGI1 encephalitis, neuropathological investigations are difficult because very little material is available. Taking advantage of this natural animal model to study pathological mechanisms will, therefore, contribute to a better understanding of its human counterpart. Here, we present a brain-wide histopathological analysis of FEPSO. We discovered that blood-brain barrier (BBB) leakage was present not only in all regions of the hippocampus but also in other limbic structures such as the subiculum, amygdale, and piriform lobe. However, in other regions, such as the cerebellum, no leakage was observed. In addition, this brain-region-specific immunoglobulin leakage was associated with the breakdown of endothelial tight junctions. Brain areas affected by BBB dysfunction also revealed immunoglobulin and complement deposition as well as neuronal cell death. These neuropathological findings were supported by magnetic resonance imaging showing signal and volume increase in the amygdala and the piriform lobe. Importantly, we could show that BBB disturbance in LGI1 encephalitis does not depend on T cell infiltrates, which were present brain-wide. This finding points toward another, so far unknown, mechanism of opening the BBB. The limbic predilection sites of immunoglobulin antibody leakage into the brain may explain why most patients with LGI1 antibodies have a limbic phenotype even though LGI1, the target protein, is ubiquitously distributed across the central nervous system.

Focused ultrasound-mediated drug delivery through the blood-brain barrier

PubMed Central

Burgess, Alison; Shah, Kairavi; Hough, Olivia; Hynynen, Kullervo

2015-01-01

Despite recent advances in blood-brain barrier (BBB) research, it remains a significant hurdle for the pharmaceutical treatment of brain diseases. Focused ultrasound (FUS) is one method to transiently increase permeability of the BBB to promote drug delivery to specific brain regions. An introduction to the BBB and a brief overview of the methods which can be used to circumvent the BBB to promote drug delivery is provided. In particular, we discuss the advantages and limitations of FUS technology and the efficacy of FUS-mediated drug delivery in models of disease. MRI for targeting and evaluating FUS treatments, combined with administration of microbubbles, allows for transient, reproducible BBB opening. The integration of a real-time acoustic feedback controller has improved treatment safety. Successful clinical translation of FUS has the potential to transform the treatment of brain disease worldwide without requiring the development of new pharmaceutical agents. PMID:25936845

Three Paths to Better Tyrosine Kinase Inhibition Behind the Blood-Brain Barrier in Treating Chronic Myelogenous Leukemia and Glioblastoma with Imatinib

PubMed Central

Kast, Richard E; Focosi, Daniele

2010-01-01

Chronic myelogenous leukemia (CML) can be controlled for years with the tyrosine kinase inhibitor imatinib but because imatinib poorly penetrates the blood-brain barrier (BBB), on occasion, the CML clone will thrive and evolve to an accelerated phase in the resulting imatinib sanctuary within the central nervous system. In this, CML resembles glioblastoma in that imatinib, which otherwise may be effective, cannot get to the tumor. Although a common street drug of abuse, methamphetamine is Food and Drug Administration-approved and marketed as a pharmaceutical drug to treat attention-deficit disorders. It has shown the ability to open the BBB in rodents. We have some clinical hints that it may do so in humans as well. This short note presents three new points potentially leading to better tyrosine kinase inhibition behind the BBB: 1) Pharmaceutical methamphetamine may have a useful role in treating both CML and glioblastoma by allowing higher imatinib concentrations behind the BBB. 2) The old antidepressant and monoamine oxidase inhibitor selegiline, used to treat Parkinson disease, is catabolized to methamphetamine. Selegiline, as a nonscheduled drug,may therefore be an easier way to open the BBB, allowing more effective chemotherapy with tyrosine kinases. 3) Dasatinib is a tyrosine kinase inhibitor with a spectrum of inhibition only partially overlapping that of imatinib and a mechanism of tyrosine kinase inhibition that is different from that of imatinib. The two should be additive. In addition, dasatinib crosses the BBB poorly, and it can therefore be expected to benefit from methamphetamine-assisted entry. PMID:20165690

Power cavitation-guided blood-brain barrier opening with focused ultrasound and microbubbles

NASA Astrophysics Data System (ADS)

Burgess, M. T.; Apostolakis, I.; Konofagou, E. E.

2018-03-01

Image-guided monitoring of microbubble-based focused ultrasound (FUS) therapies relies on the accurate localization of FUS-stimulated microbubble activity (i.e. acoustic cavitation). Passive cavitation imaging with ultrasound arrays can achieve this, but with insufficient spatial resolution. In this study, we address this limitation and perform high-resolution monitoring of acoustic cavitation-mediated blood-brain barrier (BBB) opening with a new technique called power cavitation imaging. By synchronizing the FUS transmit and passive receive acquisition, high-resolution passive cavitation imaging was achieved by using delay and sum beamforming with absolute time delays. Since the axial image resolution is now dependent on the duration of the received acoustic cavitation emission, short pulses of FUS were used to limit its duration. Image sets were acquired at high-frame rates for calculation of power cavitation images analogous to power Doppler imaging. Power cavitation imaging displays the mean intensity of acoustic cavitation over time and was correlated with areas of acoustic cavitation-induced BBB opening. Power cavitation-guided BBB opening with FUS could constitute a standalone system that may not require MRI guidance during the procedure. The same technique can be used for other acoustic cavitation-based FUS therapies, for both safety and guidance.

Power cavitation-guided blood-brain barrier opening with focused ultrasound and microbubbles.

PubMed

Burgess, M T; Apostolakis, I; Konofagou, E E

2018-03-15

Image-guided monitoring of microbubble-based focused ultrasound (FUS) therapies relies on the accurate localization of FUS-stimulated microbubble activity (i.e. acoustic cavitation). Passive cavitation imaging with ultrasound arrays can achieve this, but with insufficient spatial resolution. In this study, we address this limitation and perform high-resolution monitoring of acoustic cavitation-mediated blood-brain barrier (BBB) opening with a new technique called power cavitation imaging. By synchronizing the FUS transmit and passive receive acquisition, high-resolution passive cavitation imaging was achieved by using delay and sum beamforming with absolute time delays. Since the axial image resolution is now dependent on the duration of the received acoustic cavitation emission, short pulses of FUS were used to limit its duration. Image sets were acquired at high-frame rates for calculation of power cavitation images analogous to power Doppler imaging. Power cavitation imaging displays the mean intensity of acoustic cavitation over time and was correlated with areas of acoustic cavitation-induced BBB opening. Power cavitation-guided BBB opening with FUS could constitute a standalone system that may not require MRI guidance during the procedure. The same technique can be used for other acoustic cavitation-based FUS therapies, for both safety and guidance.

Endophilin-1 regulates blood-brain barrier permeability via EGFR-JNK signaling pathway.

PubMed

Chen, Lin; Liu, Wenjing; Wang, Ping; Xue, Yixue; Su, Qingjie; Zeng, Chaosheng; Shang, Xiuli

2015-05-05

Endophilin-1 (Endo1), a multifunctional protein, is essential for synaptic vesicle endocytosis. However, the role and mechanism of endophilin-1 in blood-brain barrier (BBB) function are still unclear. This study was performed to determine whether endophilin-1 regulated BBB permeability via the EGFR-JNK signaling pathway. In the present study, we found that endophilin-1 over-expression in human cerebral microvascular endothelial cell (hCMEC/D3) increased BBB permeability and meanwhile reduced the expression levels of epidermal growth factor receptor (EGFR), phosphorylated c-Jun N-terminal kinase (p-JNK). While endophilin-1 knockdown led to the contrary results. After JNK inhibitor SP600125 was administered to the endophilin-1 silenced hCMEC/D3 cells, the transendothelial electrical resistance (TEER) value was decreased and the permeability coefficient values to 4kDa and 40kDa FITC-dextran were increased. Results observed by Transmission electron microscopy (TEM) showed that tight junctions (TJs) were opened. Moreover, immunofluorescence and Western blot assays revealed the discontinuous distribution of TJ-associated proteins ZO-1, occludin on cell-cell boundaries and a significant decrease in protein expressing levels. Therefore, these results indicated that endophilin-1 positively regulated BBB permeability via the EGFR-JNK signaling pathway in hCMEC/D3 cells, which would provide an experimental basis for further research on endophilin-1 mediated the opening of BBB. Copyright © 2015 Elsevier B.V. All rights reserved.

Occipital blood-brain barrier permeability is an independent predictor of visual outcome in type 2 diabetes, irrespective of the retinal barrier: A longitudinal study.

PubMed

Abuhaiba, S I; Cordeiro, M; Amorim, A; Cruz, Â; Quendera, B; Ferreira, C; Ribeiro, L; Bernardes, R; Castelo-Branco, M

2018-01-01

Blood-brain barrier (BBB) permeability in type 2 diabetic patients has been previously shown to be altered in certain brain regions such as the basal ganglia and the hippocampus. Because of the histological and functional similarities between the BBB) and the blood-retinal barrier (BRB), we aimed to investigate how the permeability of both barriers predicts visual outcome. We included 2 control groups (acute unilateral stroke patients, n = 9; type 2 diabetics without BRB leakage n = 10) and a case study group of type 2 diabetics with established BRB leakage (n = 17). We evaluated sex, age, disease duration, metabolic impairment, retinopathy grade and BBB permeability as predictors of visual acuity at baseline, 12  and 24 months in the type 2 diabetics without BRB leakage group and the case study group. We have also explored differences in BBB permeability in the occipital lobe and frontal lobe in the 3 different groups. K trans (volume transfer coefficient) and V p (fractional plasma volume) were estimated. The BBB permeability parameter V p was higher in the case study group compared to the unaffected hemisphere of the stroke patient control group, suggesting vascular dynamics were changed in the occipital lobe of type 2 diabetics with established BRB leakage. These patients showed a significant correlation between glycated hemoglobin (HbA1C) levels and occipital and frontal K trans . We report for the first time that occipital BBB permeability is an independent predictor of visual acuity at baseline, as well as at 12 and 24 months, in type 2 diabetics with established BRB leakage. Our results suggest that occipital BBB permeability might be an independent biomarker for visual impairment in patients with established BRB leakage. © 2017 British Society for Neuroendocrinology.

Drug delivery across the blood-brain barrier using focused ultrasound

PubMed Central

Burgess, Alison; Hynynen, Kullervo H.

2015-01-01

Introduction The presence of the blood-brain barrier (BBB) is a significant impediment to the delivery of therapeutic agents to the brain for treatment of brain diseases. Focused ultrasound (FUS) has been developed as a non-invasive method for transiently increasing the permeability of the BBB to promote drug delivery to targeted regions of the brain. Areas Covered The present review briefly compares the methods used to promote drug delivery to the brain and describes the benefits and limitations of FUS technology. We summarize the experimental data which shows that FUS, combined with intravascular microbubbles, increases therapeutic agent delivery into the brain leading to significant reductions in pathology in preclinical models of disease. The potential for translation of this technology to the clinic is also discussed. Expert Opinion The introduction of MRI guidance and intravascular administration of microbubbles to FUS treatments permits the consistent, transient, and targeted opening of the BBB. The development of feedback systems and real-time monitoring techniques improve the safety of BBB opening. Successful clinical translation of FUS has the potential to revolutionize the treatment of brain disease resulting in effective, less-invasive treatments without the need for expensive drug development. PMID:24650132

Drug delivery across the blood-brain barrier using focused ultrasound.

PubMed

Burgess, Alison; Hynynen, Kullervo

2014-05-01

The presence of the blood-brain barrier (BBB) is a significant impediment to the delivery of therapeutic agents to the brain for treatment of brain diseases. Focused ultrasound (FUS) has been developed as a noninvasive method for transiently increasing the permeability of the BBB to promote drug delivery to targeted regions of the brain. The present review briefly compares the methods used to promote drug delivery to the brain and describes the benefits and limitations of FUS technology. We summarize the experimental data which shows that FUS, combined with intravascular microbubbles, increases therapeutic agent delivery into the brain leading to significant reductions in pathology in preclinical models of disease. The potential for translation of this technology to the clinic is also discussed. The introduction of magnetic resonance imaging guidance and intravascular administration of microbubbles to FUS treatments permits the consistent, transient and targeted opening of the BBB. The development of feedback systems and real-time monitoring techniques improve the safety of BBB opening. Successful clinical translation of FUS has the potential to revolutionize the treatment of brain disease resulting in effective, less-invasive treatments without the need for expensive drug development.

Transport of Poly(n-butylcyano-acrylate) nanoparticles across the blood-brain barrier in vitro and their influence on barrier integrity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rempe, Ralf; Cramer, Sandra; Huewel, Sabine

2011-03-04

Research highlights: {yields} Poly(n-butylcyano-acrylate) (PBCA) nanoparticles may be promising drug carriers. {yields} Influence of PBCA nanoparticles on the integrity of the blood-brain barrier in vitro. {yields} PBCA nanoparticles lead to a reversible disruption of the BBB in vitro after 4 h. {yields} Potential application as time-dependent and specific opener of the BBB. -- Abstract: In previous studies it was shown that polysorbate 80(PS80)-coated poly(n-butylcyano-acrylate) nanoparticles (PBCA-NP) are able to cross the blood-brain barrier (BBB) in vitro and in vivo. In order to explore and extend the potential applications of PBCA-NP as drug carriers, it is important to ascertain their effectmore » on the BBB. The objective of the present study was to determine the effect of PS80-coated PBCA-NP on the BBB integrity of a porcine in vitro model. This has been investigated by monitoring the development of the transendothelial electrical resistance (TEER) after the addition of PBCA-NP employing impedance spectroscopy. Additionally, the integrity of the BBB in vitro was verified by measuring the passage of the reference substances {sup 14}C-sucrose and FITC-BSA after addition of PBCA-NP. In this study we will show that the application of PS80-coated PBCA-NP leads to a reversible disruption of the barrier after 4 h. The observed disruption of the barrier could also be confirmed by {sup 14}C-sucrose and FITC-BSA permeability studies. Comparing the TEER and permeability studies the lowest resistances and maximal values for permeabilities were both observed after 4 h. These results indicate that PS80-coated PBCA-NP might be suitable for the use as drug carriers. The reversible disruption also offers the possibility to use these particles as specific opener of the BBB. Instead of incorporating the therapeutic agents into the NP, the drugs may cross the BBB after being applied simultaneously with the PBCA-NP.« less

Physiological and biochemical principles underlying volume-targeted therapy--the "Lund concept".

PubMed

Nordström, Carl-Henrik

2005-01-01

The optimal therapy of sustained increase in intracranial pressure (ICP) remains controversial. The volume-targeted therapy ("Lund concept") discussed in this article focuses on the physiological volume regulation of the intracranial compartments. The balance between effective transcapillary hydrostatic and osmotic pressures constitutes the driving force for transcapillary fluid exchange. The low permeability for sodium and chloride combined with the high crystalloid osmotic pressure (approximately 5700 mmHg) on both sides of the blood-brain barrier (BBB) counteracts fluid exchange across the intact BBB. Additionally, variations in systemic blood pressure generally are not transmitted to these capillaries because cerebral intracapillary hydrostatic pressure (and blood flow) is physio-logically tightly autoregulated. Under pathophysiological conditions, the BBB may be partially disrupted. Transcapillary water exchange is then determined by the differences in hydrostatic and colloid osmotic pressure between the intra- and extracapillary compartments. Pressure autoregulation of cerebral blood flow is likely to be impaired in these conditions. A high cerebral perfusion pressure accordingly increases intracapillary hydrostatic pressure and leads to increased intracerebral water content and an increase in ICP. The volume-targeted "Lund concept" has been evaluated in experimental and clinical studies to examine the physiological and biochemical (utilizing intracerebral microdialysis) effects, and the clinical experiences have been favorable.

Improved survival in rats with glioma using MRI-guided focused ultrasound and microbubbles to disrupt the blood-brain barrier and deliver Doxil

NASA Astrophysics Data System (ADS)

Aryal, Muna; Zhi Zhang, Yong; Vykhodtseva, Natalia; Park, Juyoung; Power, Chanikarn; McDannold, Nathan

2012-02-01

Blood-brain-barrier (BBB) limits the transportation of most neuropeptides, proteins (enzymes, antibodies), chemotherapeutic agents, and genes that have therapeutic potential for the treatment of brain diseases. Different methods have been used to overcome this limitation, but they are invasive, non-targeted, or require the development of new drugs. We have developed a method that uses MRI-guided focused ultrasound (FUS) combined with circulating microbubbles to temporarily open BBB in and around brain tumors to deliver chemotherapy agents. Here, we tested whether this noninvasive technique could enhance the effectiveness of a chemotherapy agent (Doxil). Using 690 kHz FUS transducer and microbubble (Definity), we induced BBB disruption in intracranially-implanted 9L glioma tumors in rat's brain in three weekly sessions. Animals who received BBB disruption and Doxil had a median survival time of 34.5 days, which was significantly longer than that found in control animals which is 16, 18.5, 21 days who received no treatment, BBB disruption only and Doxil only respectively This work demonstrates that FUS technique has promise in overcoming barriers to drug delivery, which are particularly stark in the brain due to the BBB.

Intra-Arterial Delivery of AAV Vectors to the Mouse Brain After Mannitol Mediated Blood Brain Barrier Disruption

PubMed Central

Santillan, Alejandro; Sondhi, Dolan; Dyke, Jonathan P.; Crystal, Ronald G.; Gobin, Y. Pierre; Ballon, Douglas J.

2014-01-01

The delivery of therapeutics to neural tissue is greatly hindered by the blood brain barrier (BBB). Direct local delivery via diffusive release from degradable implants or direct intra-cerebral injection can bypass the BBB and obtain high concentrations of the therapeutic in the targeted tissue, however the total volume of tissue that can be treated using these techniques is limited. One treatment modality that can potentially access large volumes of neural tissue in a single treatment is intra-arterial (IA) injection after osmotic blood brain barrier disruption. In this technique, the therapeutic of interest is injected directly into the arteries that feed the target tissue after the blood brain barrier has been disrupted by exposure to a hyperosmolar mannitol solution, permitting the transluminal transport of the therapy. In this work we used contrast enhanced magnetic resonance imaging (MRI) studies of IA injections in mice to establish parameters that allow for extensive and reproducible BBB disruption. We found that the volume but not the flow rate of the mannitol injection has a significant effect on the degree of disruption. To determine whether the degree of disruption we observed with this method was sufficient for delivery of nanoscale therapeutics, we performed IA injections of an adeno-associated viral vector containing the CLN2 gene (AAVrh.10CLN2), which is mutated in the lysosomal storage disorder Late Infantile Neuronal Ceroid Lipofuscinosis (LINCL). We demonstrated that IA injection of AAVrh.10CLN2 after BBB disruption can achieve widespread transgene production in the mouse brain after a single administration. Further, we showed that there exists a minimum threshold of BBB disruption necessary to permit the AAV.rh10 vector to pass into the brain parenchyma from the vascular system. These results suggest that IA administration may be used to obtain widespread delivery of nanoscale therapeutics throughout the murine brain after a single administration. PMID:25270115

Ultrasound-mediated blood-brain barrier disruption for targeted drug delivery in the central nervous system

PubMed Central

Aryal, Muna; Arvanitis, Costas D.; Alexander, Phillip M.; McDannold, Nathan

2014-01-01

The physiology of the vasculature in the central nervous system (CNS), which includes the blood-brain barrier (BBB) and other factors, complicates the delivery of most drugs to the brain. Different methods have been used to bypass the BBB, but they have limitations such as being invasive, non-targeted or requiring the formulation of new drugs. Focused ultrasound (FUS), when combined with circulating microbubbles, is a noninvasive method to locally and transiently disrupt the BBB at discrete targets. This review provides insight on the current status of this unique drug delivery technique, experience in preclinical models, and potential for clinical translation. If translated to humans, this method would offer a flexible means to target therapeutics to desired points or volumes in the brain, and enable the whole arsenal of drugs in the CNS that are currently prevented by the BBB. PMID:24462453

Noninvasive Blood-Brain Barrier Opening in Live Mice

NASA Astrophysics Data System (ADS)

Choi, James J.; Pernot, Mathieu; Small, Scott; Konofagou, Elisa E.

2006-05-01

Most therapeutic agents cannot be delivered to the brain because of brain's natural defense: the Blood-Brain Barrier (BBB). It has recently been shown that Focused Ultrasound (FUS) can produce reversible and localized BBB opening in the brain when applied in the presence of ultrasound contrast agents post-craniotomy in rabbits [1]. However, a major limitation of ultrasound in the brain is the strong phase aberration and attenuation of the skull bone, and, as a result, no study of trans-cranial ultrasound-targeted drug treatment in the brain in vivo has been reported as of yet. In this study, the feasibility of BBB opening in the hippocampus of wildtype mice using FUS through the intact skull and skin was investigated. In order to investigate the effect of the skull, simulations of ultrasound wave propagation (1.5 MHz) through the skull using μCT data, and needle hydrophone measurements through an ex-vivo skull were made. The pressure field showed minimal attenuation (18% of the pressure amplitude) and a well-focused pattern through the left and right halves of the parietal bone. In experiments in vivo, the brains of four mice were sonicated through intact skull and skin. Ultrasound sonications (burst length: 20 ms; duty cycle: 20%; acoustic pressure range: 2.0 to 2.7 MPa) was applied 5 times for 30 s per shot with a 30 s delay between shots. Prior to sonication, ultrasound contrast agents (Optison; 10 μL) were injected intravenously. Contrast material enhanced high resolution MR Imaging (9.4 Tesla) was able to distinguish opening of large vessels in the region of the hippocampus. These results demonstrate the feasibility of locally opening the BBB in the mouse hippocampus using focused ultrasound through intact skull and skin. Future investigations will deal with optimization and reproducibility of the technique as well as application on Alzheimer's-model mice.

MR-Guided Unfocused Ultrasound Disruption of the Rat Blood-Brain Barrier

NASA Astrophysics Data System (ADS)

Townsend, Kelly A.; King, Randy L.; Zaharchuk, Greg; Pauly, Kim Butts

2011-09-01

Therapeutic ultrasound with microbubbles can temporarily disrupt the blood-brain barrier (BBB) for drug delivery. Contrast-enhanced MRI (CE-MRI) can visualize gadolinium passage into the brain, indicating BBB opening. Previous studies used focused ultrasound, which is appropriate for the targeted delivery of drugs. The purpose of this study was to investigate unfocused ultrasound for BBB opening across the whole brain. In 10 rats, gadolinium-based MR contrast agent (Gd; 0.25 ml) was administered concurrent with ultrasound microbubbles (Optison, 0.25 ml) and circulated for 20 sec before sonication. A 753 kHz planar PZT transducer, diameter 1.8 cm, sonicated each rat brain with supplied voltage of 300, 400, or 500 mVpp for 10 sec in continuous wave mode, or at 500 mVpp at 20% duty cycle at 10 Hz for 30-300 sec. After sonication, coronal T1-weighted FSE CE-MRI images were acquired with a 3in surface coil. The imaging protocol was repeated 3-5 times after treatment. One control animal was given Gd and microbubbles, but not sonicated, and the other was given Gd and sonicated without microbubbles. Signal change in ROIs over the muscle, mesencephalon/ventricles, and the cortex/striatum were measured at 3-5 time points up to 36 min after sonication. Signal intensity was converted to % signal change compared to the initial image. In the controls, CE-MRI showed brightening of surrounding structures, but not the brain. In the continuous wave subjects, cortex/striatum signal did not increase, but ventricle/mesenchephalon signal did. Those that received pulsed sonications showed signal increases in both the cortex/striatum and ventricles/mesenchephalon. In conclusion, after pulsed unfocused ultrasound sonication, the BBB is disrupted across the whole brain, including cortex and deep grey matter, while continuous wave sonication affects only the ventricles and possibly deeper structures, without opening the cortex BBB. As time passes, the timeline of Gd passage into the brain can be visualized.

Rivaroxaban does not influence hemorrhagic transformation in a diabetes ischemic stroke and endovascular thrombectomy model.

PubMed

Liu, Feng-Di; Zhao, Rong; Feng, Xiao-Yan; Shi, Yan-Hui; Wu, Yi-Lan; Shen, Xiao-Lei; Li, Ge-Fei; Liu, Yi-Sheng; Zhao, Ying; He, Xin-Wei; Yin, Jia-Wen; Zhuang, Mei-Ting; Zhao, Bing-Qiao; Liu, Jian-Ren

2018-05-09

Managing endovascular thrombectomy (ET) in diabetic ischemic stroke (IS) with novel anticoagulants is challenging due to putative risk of intracerebral hemorrhage. The study evaluates increased hemorrhagic transformation (HT) risk in Rivaroxaban-treated diabetic rats post ET. Diabetes was induced in male Sprague-Dawley rats by intraperitoneal injection of 60 mg/kg streptozotocin. After 4-weeks, rats were pretreated orally with 30 mg/kg Rivaroxaban/saline; prothrombin time was monitored. IS and ET was induced after 1 h, by thread-induced transient middle cerebral artery occlusion (tMCAO) that mimicked mechanical ET for proximal MCA occlusion at 60 min. After 24 h reperfusion, infarct volumes, HT, blood-brain barrier (BBB) permeability, tight junction at peri-ischemic lesion and matrix metalloproteinase-9 (MMP-9) activity was measured. Diabetic rats seemed to exhibit increased infarct volume and HT at 24 h after ET than normal rats. Infarct volumes and functional outcomes did not differ between Rivaroxaban and diabetic control groups. A significant increase in HT volumes and BBB permeability under Rivaroxaban treatment was not detected. Compared to diabetic control group, neither the occludin expression was remarkably lower in the Rivaroxaban group nor the MMP-9 activity was higher. Together, Rivaroxaban does not increase HT after ET in diabetic rats with proximal MCA occlusion, since Rivaroxaban has fewer effects on post-ischemic BBB permeability.

Blood-brain barrier transport of an essential amino acid after cerebral ischemia reperfusion injury.

PubMed

Suzuki, Toyofumi; Miyazaki, Yumiko; Ohmuro, Aya; Watanabe, Masaki; Furuishi, Takayuki; Fukami, Toshiro; Tomono, Kazuo

2013-01-01

Under pathophysiological conditions such as -cerebral ischemia-reperfusion (IR), damage to cerebrovascular endothelial cells causes alterations in the blood-brain barrier (BBB) function that can exacerbate neuronal cell injury and death. Clarifying changes in BBB transport in the early period of IR is important for understanding BBB function during therapy after cerebral ischemia. The present study was aimed at clarifying changes during IR in the BBB transport of L-phenylalanine (Phe) as a substrate of L-type amino acid transporter 1. An IR model was produced in mice by blood recirculation following occlusion of the middle cerebral artery. Permeability of the BBB to [(3)H]Phe was measured after IR injury using the brain perfusion method. Confocal microscopy of the IR injury showed no brain penetration of fluorescent tracer, thus confirming BBB integrity during 45 min of ischemia. Tight junction opening was not observed at 30 min after reperfusion following ischemia for 45 min. At the time of IR, [(3)H]Phe uptake into the brain appeared saturated. The Michaelis constant and maximum transport velocity in the IR group was reduced by 22 % compared with those in controls. These results suggest that the intrinsic transport clearance of Phe is slightly decreased in the early phase of IR.

The blood-brain barrier as a target in traumatic brain injury treatment.

PubMed

Thal, Serge C; Neuhaus, Winfried

2014-11-01

Traumatic brain injury (TBI) is one of the most frequent causes of death in the young population. Several clinical trials have unsuccessfully focused on direct neuroprotective therapies. Recently immunotherapeutic strategies shifted into focus of translational research in acute CNS diseases. Cross-talk between activated microglia and blood-brain barrier (BBB) could initiate opening of the BBB and subsequent recruitment of systemic immune cells and mediators into the brain. Stabilization of the BBB after TBI could be a promising strategy to limit neuronal inflammation, secondary brain damage and acute neurodegeneration. This review provides an overview on the pathophysiology of TBI and brain edema formation including definitions and classification of TBI, current clinical treatment strategies, as well as current understanding on the underlying cellular processes. A summary of in vivo and in vitro models to study different aspects of TBI is presented. Three mechanisms proposed for stabilization of the BBB, myosin light chain kinases, glucocorticoid receptors and peroxisome proliferator-activated receptors are reviewed for their influence on barrier-integrity and outcome after TBI. In conclusion, the BBB is recommended as a promising target for the treatment of traumatic brain injury, and it is suggested that a combination of BBB stabilization and neuroprotectants may improve therapeutic success. Copyright © 2015 IMSS. Published by Elsevier Inc. All rights reserved.

Approaching complete inhibition of P-glycoprotein at the human blood-brain barrier: an (R)-[11C]verapamil PET study.

PubMed

Bauer, Martin; Karch, Rudolf; Zeitlinger, Markus; Philippe, Cécile; Römermann, Kerstin; Stanek, Johann; Maier-Salamon, Alexandra; Wadsak, Wolfgang; Jäger, Walter; Hacker, Marcus; Müller, Markus; Langer, Oliver

2015-05-01

As P-glycoprotein (Pgp) inhibition at the blood-brain barrier (BBB) after administration of a single dose of tariquidar is transient, we performed positron emission tomography (PET) scans with the Pgp substrate (R)-[(11)C]verapamil in five healthy volunteers during continuous intravenous tariquidar infusion. Total distribution volume (VT) of (R)-[(11)C]verapamil in whole-brain gray matter increased by 273 ± 78% relative to baseline scans without tariquidar, which was higher than previously reported VT increases. During tariquidar infusion whole-brain VT was comparable to VT in the pituitary gland, a region not protected by the BBB, which suggested that we were approaching complete Pgp inhibition at the human BBB.

Electroacupuncture: a new approach to open the blood-brain barrier in rats recovering from middle cerebral artery occlusion.

PubMed

Zhang, Jiangsong; Lin, Xianming; Zhou, Hui; Chen, Yuanyuan; Xiao, Shuangkai; Jiao, Junyue; Zhao, Yibin; Di, Zhong

2018-06-14

To examine for an opening effect on the blood-brain barrier (BBB) in intact rats and rats with experimental ischaemia-reperfusion (I/R) during the recovery period after various electroacupuncture (EA) treatments with different time courses, and to determine whether there is a time-dependent effect. An additional objective was to determine whether this method could induce the penetration of nerve growth factor (NGF) through the BBB. A middle cerebral artery occlusion (MCAO) model was first established. We chose different stimulation time courses and observed the effects of EA treatment (100 Hz frequency; 2 mA intensity) at GV20 and GV26 on the BBB in rats recovering from MCAO 3 weeks after modelling. The rats were injected with 2% Evans blue (EB) saline. The brain water content was measured using a wet/dry weighing method. The degree of penetration of EB was detected using spectrophotometry and laser confocal microscopy. The rats were then injected with NGF, and the concentration of NGF in the brain tissues was measured using ELISA. The increase in the BBB permeability was most notable following the 8 min EA stimulation (P<0.05), which may be advantageous for the targeted delivery of drugs (such as NGF) into the brain. Additionally, this effect did not appear to cause brain oedema (P>0.05) in healthy or MCAO rats. EA treatment for a certain stimulation time at GV20 and GV26 in MCAO rats can increase BBB permeability. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Nanobiotechnology-based strategies for crossing the blood-brain barrier.

PubMed

Jain, Kewal K

2012-08-01

The blood-brain barrier (BBB) is meant to protect the brain from noxious agents; however, it also significantly hinders the delivery of therapeutics to the brain. Several strategies have been employed to deliver drugs across this barrier and some of these may do structural damage to the BBB by forcibly opening it to allow the uncontrolled passage of drugs. The ideal method for transporting drugs across the BBB should be controlled and should not damage the barrier. Among the various approaches that are available, nanobiotechnology-based delivery methods provide the best prospects for achieving this ideal. This review describes various nanoparticle (NP)-based methods used for drug delivery to the brain and the known underlying mechanisms. Some strategies require multifunctional NPs combining controlled passage across the BBB with targeted delivery of the therapeutic cargo to the intended site of action in the brain. An important application of nanobiotechnology is to facilitate the delivery of drugs and biological therapeutics for brain tumors across the BBB. Although there are currently some limitations and concerns for the potential neurotoxicity of NPs, the future prospects for NP-based therapeutic delivery to the brain are excellent.

Glutamate-Mediated Blood-Brain Barrier Opening: Implications for Neuroprotection and Drug Delivery.

PubMed

Vazana, Udi; Veksler, Ronel; Pell, Gaby S; Prager, Ofer; Fassler, Michael; Chassidim, Yoash; Roth, Yiftach; Shahar, Hamutal; Zangen, Abraham; Raccah, Ruggero; Onesti, Emanuela; Ceccanti, Marco; Colonnese, Claudio; Santoro, Antonio; Salvati, Maurizio; D'Elia, Alessandro; Nucciarelli, Valter; Inghilleri, Maurizio; Friedman, Alon

2016-07-20

The blood-brain barrier is a highly selective anatomical and functional interface allowing a unique environment for neuro-glia networks. Blood-brain barrier dysfunction is common in most brain disorders and is associated with disease course and delayed complications. However, the mechanisms underlying blood-brain barrier opening are poorly understood. Here we demonstrate the role of the neurotransmitter glutamate in modulating early barrier permeability in vivo Using intravital microscopy, we show that recurrent seizures and the associated excessive glutamate release lead to increased vascular permeability in the rat cerebral cortex, through activation of NMDA receptors. NMDA receptor antagonists reduce barrier permeability in the peri-ischemic brain, whereas neuronal activation using high-intensity magnetic stimulation increases barrier permeability and facilitates drug delivery. Finally, we conducted a double-blind clinical trial in patients with malignant glial tumors, using contrast-enhanced magnetic resonance imaging to quantitatively assess blood-brain barrier permeability. We demonstrate the safety of stimulation that efficiently increased blood-brain barrier permeability in 10 of 15 patients with malignant glial tumors. We suggest a novel mechanism for the bidirectional modulation of brain vascular permeability toward increased drug delivery and prevention of delayed complications in brain disorders. In this study, we reveal a new mechanism that governs blood-brain barrier (BBB) function in the rat cerebral cortex, and, by using the discovered mechanism, we demonstrate bidirectional control over brain endothelial permeability. Obviously, the clinical potential of manipulating BBB permeability for neuroprotection and drug delivery is immense, as we show in preclinical and proof-of-concept clinical studies. This study addresses an unmet need to induce transient BBB opening for drug delivery in patients with malignant brain tumors and effectively facilitate BBB closure in neurological disorders. Copyright © 2016 the authors 0270-6474/16/367727-13$15.00/0.

Glutamate-Mediated Blood–Brain Barrier Opening: Implications for Neuroprotection and Drug Delivery

PubMed Central

Vazana, Udi; Veksler, Ronel; Pell, Gaby S.; Prager, Ofer; Fassler, Michael; Chassidim, Yoash; Roth, Yiftach; Shahar, Hamutal; Zangen, Abraham; Raccah, Ruggero; Onesti, Emanuela; Ceccanti, Marco; Colonnese, Claudio; Santoro, Antonio; Salvati, Maurizio; D'Elia, Alessandro; Nucciarelli, Valter; Inghilleri, Maurizio

2016-01-01

The blood–brain barrier is a highly selective anatomical and functional interface allowing a unique environment for neuro-glia networks. Blood–brain barrier dysfunction is common in most brain disorders and is associated with disease course and delayed complications. However, the mechanisms underlying blood–brain barrier opening are poorly understood. Here we demonstrate the role of the neurotransmitter glutamate in modulating early barrier permeability in vivo. Using intravital microscopy, we show that recurrent seizures and the associated excessive glutamate release lead to increased vascular permeability in the rat cerebral cortex, through activation of NMDA receptors. NMDA receptor antagonists reduce barrier permeability in the peri-ischemic brain, whereas neuronal activation using high-intensity magnetic stimulation increases barrier permeability and facilitates drug delivery. Finally, we conducted a double-blind clinical trial in patients with malignant glial tumors, using contrast-enhanced magnetic resonance imaging to quantitatively assess blood–brain barrier permeability. We demonstrate the safety of stimulation that efficiently increased blood–brain barrier permeability in 10 of 15 patients with malignant glial tumors. We suggest a novel mechanism for the bidirectional modulation of brain vascular permeability toward increased drug delivery and prevention of delayed complications in brain disorders. SIGNIFICANCE STATEMENT In this study, we reveal a new mechanism that governs blood–brain barrier (BBB) function in the rat cerebral cortex, and, by using the discovered mechanism, we demonstrate bidirectional control over brain endothelial permeability. Obviously, the clinical potential of manipulating BBB permeability for neuroprotection and drug delivery is immense, as we show in preclinical and proof-of-concept clinical studies. This study addresses an unmet need to induce transient BBB opening for drug delivery in patients with malignant brain tumors and effectively facilitate BBB closure in neurological disorders. PMID:27445149

The role of protein kinase C in the opening of blood-brain barrier induced by electromagnetic pulse.

PubMed

Qiu, Lian-Bo; Ding, Gui-Rong; Li, Kang-Chu; Wang, Xiao-Wu; Zhou, Yan; Zhou, Yong-Chun; Li, Yu-Rong; Guo, Guo-Zhen

2010-06-29

The aim of this study was to determine the role of protein kinase C signaling in electromagnetic pulse (EMP)-induced blood-brain barrier (BBB) permeability change in rats. The protein level of total PKC and two PKC isoforms (PKC-alpha, and PKC-beta II) were determined in brain cerebral cortex microvessels by Western blot after exposing rats to EMP at 200kV/m for 200 pulses with 1Hz repetition rate. It was found that the protein level of PKC and PKC-betaII (but not PKC-alpha) in cerebral cortex microvessels increased significantly at 0.5h and 1h after EMP exposure compared with sham-exposed animals and then recovered at 3h. A specific PKC antagonist (H7) almost blocked EMP-induced BBB permeability change. EMP-induced BBB tight junction protein ZO-1 translocation was also inhibited. Our data indicated that PKC signaling was involved in EMP-induced BBB permeability change and ZO-1 translocation in rat.

Blood-brain barrier dysfunction following traumatic brain injury: correlation of K(trans) (DCE-MRI) and SUVR (99mTc-DTPA SPECT) but not serum S100B.

PubMed

Winter, Craig; Bell, Christopher; Whyte, Timothy; Cardinal, John; Macfarlane, David; Rose, Stephen

2015-07-01

Damage to the blood-brain barrier (BBB) is an important secondary mechanism that occurs following traumatic brain injury (TBI) and may provide a potential therapeutic target to improve patient outcome. For such a progress to be realised, an accurate assessment of BBB compromise needs to be established. Fourteen patients with TBI were prospectively recruited. Post-traumatic BBB dysfunction was assessed using dynamic contrast-enhanced MRI (DCE-MRI), single-photon emission computerised tomography (SPECT) and serum S100B levels. A statistically significant correlation between standardised uptake value ratio (SUVR) calculated from 99mTc-DTPA SPECT and K(trans) (a volume transfer constant) from DCE-MRI was found for those eight patients who had concurrent scans. The positive correlation persisted when the data were corrected for patient age, number of days following trauma and both parameters combined. We found no statistically significant correlation between either of the imaging modalities and concurrent serum S100B levels. The correlation of SPECT with DCE-MRI suggests that either scan may be used to assess post-traumatic BBB damage. We could not support serum S100B to be an accurate measure of BBB damage when sampled a number of days following injury but the small number of patients, the heterogeneity in TBI patients and the delay following injury makes any firm conclusions regarding S100B and BBB difficult.

Glioma targeting and blood-brain barrier penetration by dual-targeting doxorubincin liposomes.

PubMed

Gao, Jian-Qing; Lv, Qing; Li, Li-Ming; Tang, Xin-Jiang; Li, Fan-Zhu; Hu, Yu-Lan; Han, Min

2013-07-01

Effective chemotherapy for glioblastoma requires a carrier that can penetrate the blood-brain barrier (BBB) and subsequently target the glioma cells. Dual-targeting doxorubincin (Dox) liposomes were produced by conjugating liposomes with both folate (F) and transferrin (Tf), which were proven effective in penetrating the BBB and targeting tumors, respectively. The liposome was characterized by particle size, Dox entrapment efficiency, and in vitro release profile. Drug accumulation in cells, P-glycoprotein (P-gp) expression, and drug transport across the BBB in the dual-targeting liposome group were examined by using bEnd3 BBB models. In vivo studies demonstrated that the dual-targeting Dox liposomes could transport across the BBB and mainly distribute in the brain glioma. The anti-tumor effect of the dual-targeting liposome was also demonstrated by the increased survival time, decreased tumor volume, and results of both hematoxylin-eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling analysis. The dual-targeting Dox liposome could improve the therapeutic efficacy of brain glioma and were less toxic than the Dox solution, showing a dual-targeting effect. These results indicate that this dual-targeting liposome can be used as a potential carrier for glioma chemotherapy. Copyright © 2013 Elsevier Ltd. All rights reserved.

Tetramethylpyrazine-2'-O-sodium ferulate attenuates blood-brain barrier disruption and brain oedema after cerebral ischemia/reperfusion.

PubMed

Xu, S-H; Yin, M-S; Liu, B; Chen, M-L; He, G-W; Zhou, P-P; Cui, Y-J; Yang, D; Wu, Y-L

2017-07-01

Disruption of blood-brain barrier (BBB) and subsequent oedema are major causes of the pathogenesis in ischaemic stroke with which the current clinical therapy remains unsatisfied. In this study, we examined the therapeutic effect of tetramethylpyrazine-2'-O-sodium ferulate (TSF)-a novel analogue of tetramethylpyrazine in alleviating BBB breakdown and brain oedema after cerebral ischaemia/reperfusion (I/R). Then, we explored the potential mechanism of the protection on BBB disruption in cerebral I/R rat models. Male Sprague-Dawley rats (250-300 g) were subjected to 120 min middle cerebral artery occlusion (MCAO), followed by 48 h reperfusion. TSF (10.8, 18 and 30 mg kg -1 ) and ozagrel (18 mg kg -1 ) were administrated by intravenous injection immediately for the first time and then received the same dose every 24 h for 2 days. We found that TSF treatment significantly attenuated the cerebral water content, infarction volume and improved neurological outcomes in MCAO rats compared to I/R models. Moreover, we investigated the effect of TSF on the BBB for that cerebral oedema is closely related to the permeability of the BBB. We found that the permeability of BBB was improved significantly in TSF groups compared to I/R model group by Evans blue leakage testing. Furthermore, the expressions of tight junction (TJ) proteins junction adhesion molecule-1 and occludin significantly decreased, but the protein expression of matrix metalloproteinase-9 (MMP-9) and aquaporin 4 (AQP4) increased after cerebral I/R, all of which were alleviated by TSF treatment. In conclusion, TSF significantly reduced BBB permeability and brain oedema, which were correlated with regulating the expression of TJ proteins, MMP-9 and AQP4. These findings provide a novel approach to the treatment of ischaemic stroke.

Controlled Ultrasound-Induced Blood-Brain Barrier Disruption Using Passive Acoustic Emissions Monitoring

PubMed Central

Arvanitis, Costas D.; Livingstone, Margaret S.; Vykhodtseva, Natalia; McDannold, Nathan

2012-01-01

The ability of ultrasonically-induced oscillations of circulating microbubbles to permeabilize vascular barriers such as the blood-brain barrier (BBB) holds great promise for noninvasive targeted drug delivery. A major issue has been a lack of control over the procedure to ensure both safe and effective treatment. Here, we evaluated the use of passively-recorded acoustic emissions as a means to achieve this control. An acoustic emissions monitoring system was constructed and integrated into a clinical transcranial MRI-guided focused ultrasound system. Recordings were analyzed using a spectroscopic method that isolates the acoustic emissions caused by the microbubbles during sonication. This analysis characterized and quantified harmonic oscillations that occur when the BBB is disrupted, and broadband emissions that occur when tissue damage occurs. After validating the system's performance in pilot studies that explored a wide range of exposure levels, the measurements were used to control the ultrasound exposure level during transcranial sonications at 104 volumes over 22 weekly sessions in four macaques. We found that increasing the exposure level until a large harmonic emissions signal was observed was an effective means to ensure BBB disruption without broadband emissions. We had a success rate of 96% in inducing BBB disruption as measured by in contrast-enhanced MRI, and we detected broadband emissions in less than 0.2% of the applied bursts. The magnitude of the harmonic emissions signals was significantly (P<0.001) larger for sonications where BBB disruption was detected, and it correlated with BBB permeabilization as indicated by the magnitude of the MRI signal enhancement after MRI contrast administration (R2 = 0.78). Overall, the results indicate that harmonic emissions can be a used to control focused ultrasound-induced BBB disruption. These results are promising for clinical translation of this technology. PMID:23029240

A polymeric micelle magnetic resonance imaging (MRI) contrast agent reveals blood-brain barrier (BBB) permeability for macromolecules in cerebral ischemia-reperfusion injury.

PubMed

Shiraishi, Kouichi; Wang, Zuojun; Kokuryo, Daisuke; Aoki, Ichio; Yokoyama, Masayuki

2017-05-10

Blood-brain barrier (BBB) opening is a key phenomenon for understanding ischemia-reperfusion injuries that are directly linked to hemorrhagic transformation. The recombinant human tissue-type plasminogen activator (rtPA) increases the risk of symptomatic intracranial hemorrhages. Recent imaging technologies have advanced our understanding of pathological BBB disorders; however, an ongoing challenge in the pre-"rtPA treatment" stage is the task of developing a rigorous method for hemorrhage-risk assessments. Therefore, we examined a novel method for assessment of rtPA-extravasation through a hyper-permeable BBB. To examine the image diagnosis of rtPA-extravasation for a rat transient occlusion-reperfusion model, in this study we used a polymeric micelle MRI contrast-agent (Gd-micelles). Specifically, we used two MRI contrast agents at 1h after reperfusion. Gd-micelles provided very clear contrast images in 15.5±10.3% of the ischemic hemisphere at 30min after i.v. injection, whereas a classic gadolinium chelate MRI contrast agent provided no satisfactorily clear images. The obtained images indicate both the hyper-permeable BBB area for macromolecules and the distribution area of macromolecules in the ischemic hemisphere. Owing to their large molecular weight, Gd-micelles remained in the ischemic hemisphere through the hyper-permeable BBB. Our results indicate the feasibility of a novel clinical diagnosis for evaluating rtPA-related hemorrhage risks. Copyright © 2017 Elsevier B.V. All rights reserved.

Vascular tight junction disruption and angiogenesis in spontaneously hypertensive rat with neuroinflammatory white matter injury.

PubMed

Yang, Yi; Kimura-Ohba, Shihoko; Thompson, Jeffrey F; Salayandia, Victor M; Cossé, Melissa; Raz, Limor; Jalal, Fakhreya Y; Rosenberg, Gary A

2018-06-01

Vascular cognitive impairment is a major cause of dementia caused by chronic hypoxia, producing progressive damage to white matter (WM) secondary to blood-brain barrier (BBB) opening and vascular dysfunction. Tight junction proteins (TJPs), which maintain BBB integrity, are lost in acute ischemia. Although angiogenesis is critical for neurovascular remodeling, less is known about its role in chronic hypoxia. To study the impact of TJP degradation and angiogenesis during pathological progression of WM damage, we used the spontaneously hypertensive/stroke prone rats with unilateral carotid artery occlusion and Japanese permissive diet to model WM damage. MRI and IgG immunostaining showed regions with BBB damage, which corresponded with decreased endothelial TJPs, claudin-5, occludin, and ZO-1. Affected WM had increased expression of angiogenic factors, Ki67, NG2, VEGF-A, and MMP-3 in vascular endothelial cells and pericytes. To facilitate the study of angiogenesis, we treated rats with minocycline to block BBB disruption, reduce WM lesion size, and extend survival. Minocycline-treated rats showed increased VEGF-A protein, TJP formation, and oligodendrocyte proliferation. We propose that chronic hypoxia disrupts TJPs, increasing vascular permeability, and initiating angiogenesis in WM. Minocycline facilitated WM repair by reducing BBB damage and enhancing expression of TJPs and angiogenesis, ultimately preserving oligodendrocytes. Copyright © 2018 Elsevier Inc. All rights reserved.

Examination of Blood-Brain Barrier (BBB) Integrity In A Mouse Brain Tumor Model

PubMed Central

On, Ngoc; Mitchell, Ryan; Savant, Sanjot D.; Bachmeier, Corbin. J.; Hatch, Grant M.; Miller, Donald W.

2013-01-01

The present study evaluates, both functionally and biochemically, brain tumor-induced alterations in brain capillary endothelial cells. Brain tumors were induced in Balb/c mice via intracranial injection of Lewis Lung carcinoma (3LL) cells into the right hemisphere of the mouse brain using stereotaxic apparatus. Blood-brain barrier (BBB) permeability was assessed at various stages of tumor development, using both radiolabeled tracer permeability and magnetic resonance imaging (MRI) with gadolinium diethylene-triamine-pentaacetate contrast enhancement (Gad-DTPA). The expression of the drug efflux transporter, P-glycoprotein (P-gp), in the BBB at various stages of tumor development was also evaluated by Western blot and immunohistochemistry. Median mouse survival following tumor cell injection was 17 days. The permeability of the BBB to 3H-mannitol was similar in both brain hemispheres at 7 and 10 days post-injection. By day 15, there was a 2-fold increase in 3H-mannitol permeability in the tumor bearing hemispheres compared to the non-tumor hemispheres. Examination of BBB permeability with Gad-DTPA contrast enhanced MRI indicated cerebral vascular permeability changes were confined to the tumor area. The permeability increase observed at the later stages of tumor development correlated with an increase in cerebral vascular volume suggesting angiogenesis within the tumor bearing hemisphere. Furthermore, the Gad-DPTA enhancement observed within the tumor area was significantly less than Gad-DPTA enhancement within the circumventricular organs not protected by the BBB. Expression of P-gp in both the tumor bearing and non-tumor bearing portions of the brain appeared similar at all time points examined. These studies suggest that although BBB integrity is altered within the tumor site at later stages of development, the BBB is still functional and limiting in terms of solute and drug permeability in and around the tumor. PMID:23184143

Long-Term Safety of Repeated Blood-Brain Barrier Opening via Focused Ultrasound with Microbubbles in Non-Human Primates Performing a Cognitive Task.

PubMed

Downs, Matthew E; Buch, Amanda; Sierra, Carlos; Karakatsani, Maria Eleni; Teichert, Tobias; Chen, Shangshang; Konofagou, Elisa E; Ferrera, Vincent P

2015-01-01

Focused Ultrasound (FUS) coupled with intravenous administration of microbubbles (MB) is a non-invasive technique that has been shown to reliably open (increase the permeability of) the blood-brain barrier (BBB) in multiple in vivo models including non-human primates (NHP). This procedure has shown promise for clinical and basic science applications, yet the safety and potential neurological effects of long term application in NHP requires further investigation under parameters shown to be efficacious in that species (500 kHz, 200-400 kPa, 4-5 μm MB, 2 minute sonication). In this study, we repeatedly opened the BBB in the caudate and putamen regions of the basal ganglia of 4 NHP using FUS with systemically-administered MB over 4-20 months. We assessed the safety of the FUS with MB procedure using MRI to detect edema or hemorrhaging in the brain. Contrast enhanced T1-weighted MRI sequences showed a 98% success rate for openings in the targeted regions. T2-weighted and SWI sequences indicated a lack edema in the majority of the cases. We investigated potential neurological effects of the FUS with MB procedure through quantitative cognitive testing of' visual, cognitive, motivational, and motor function using a random dot motion task with reward magnitude bias presented on a touchpanel display. Reaction times during the task significantly increased on the day of the FUS with MB procedure. This increase returned to baseline within 4-5 days after the procedure. Visual motion discrimination thresholds were unaffected. Our results indicate FUS with MB can be a safe method for repeated opening of the BBB at the basal ganglia in NHP for up to 20 months without any long-term negative physiological or neurological effects with the parameters used.

Phosphorylated recombinant HSP27 protects the brain and attenuates blood-brain barrier disruption following stroke in mice receiving intravenous tissue-plasminogen activator.

PubMed

Shimada, Yoshiaki; Shimura, Hideki; Tanaka, Ryota; Yamashiro, Kazuo; Koike, Masato; Uchiyama, Yasuo; Urabe, Takao; Hattori, Nobutaka

2018-01-01

Loss of integrity of the blood-brain barrier (BBB) in ischemic stroke victims initiates a devastating cascade of events causing brain damage. Maintaining the BBB is important to preserve brain function in ischemic stroke. Unfortunately, recombinant tissue plasminogen activator (tPA), the only effective fibrinolytic treatment at the acute stage of ischemic stroke, also injures the BBB and increases the risk of brain edema and secondary hemorrhagic transformation. Thus, it is important to identify compounds that maintain BBB integrity in the face of ischemic injury in patients with stroke. We previously demonstrated that intravenously injected phosphorylated recombinant heat shock protein 27 (prHSP27) protects the brains of mice with transient middle cerebral artery occlusion (tMCAO), an animal stroke-model. Here, we determined whether prHSP27, in addition to attenuating brain injury, also decreases BBB damage in hyperglycemic tMCAO mice that had received tPA. After induction of hyperglycemia and tMCAO, we examined 4 treatment groups: 1) bovine serum albumin (BSA), 2) prHSP27, 3) tPA, 4) tPA plus prHSP27. We examined the effects of prHSP27 by comparing the BSA and prHSP27 groups and the tPA and tPA plus prHSP27 groups. Twenty-four hours after injection, prHSP27 reduced infarct volume, brain swelling, neurological deficits, the loss of microvessel proteins and endothelial cell walls, and mortality. It also reduced the rates of hemorrhagic transformation, extravasation of endogenous IgG, and MMP-9 activity, signs of BBB damage. Therefore, prHSP27 injection attenuated brain damage and preserved the BBB in tPA-injected, hyperglycemic tMCAO experimental stroke-model mice, in which the BBB is even more severely damaged than in simple tMCAO mice. The attenuation of brain damage and BBB disruption in the presence of tPA suggests the effectiveness of prHSP27 and tPA as a combination therapy. prHSP27 may be a novel therapeutic agent for ischemic stroke patients whose BBBs are injured following tPA injections.

Modulatory effects of perforin gene dosage on pathogen-associated blood-brain barrier (BBB) disruption.

PubMed

Willenbring, Robin C; Jin, Fang; Hinton, David J; Hansen, Mike; Choi, Doo-Sup; Pavelko, Kevin D; Johnson, Aaron J

2016-08-31

CD8 T cell-mediated blood-brain barrier (BBB) disruption is dependent on the effector molecule perforin. Human perforin has extensive single nucleotide variants (SNVs), the significance of which is not fully understood. These SNVs can result in reduced, but not ablated, perforin activity or expression. However, complete loss of perforin expression or activity results in the lethal disease familial hemophagocytic lymphohistiocytosis type 2 (FHL 2). In this study, we address the hypothesis that a single perforin allele can alter the severity of BBB disruption in vivo using a well-established model of CNS vascular permeability in C57Bl/6 mice. The results of this study provide insight into the significance of perforin SNVs in the human population. We isolated the effect a single perforin allele has on CNS vascular permeability through the use of perforin-heterozygous (perforin+/-) C57BL/6 mice in the peptide-induced fatal syndrome (PIFS) model of immune-mediated BBB disruption. Seven days following Theiler's murine encephalomyelitis virus (TMEV) CNS infection, neuroinflammation and TMEV viral control were assessed through flow cytometric analysis and quantitative real-time PCR of the viral genome, respectively. Following immune-mediated BBB disruption, gadolinium-enhanced T1-weighted MRI, with 3D volumetric analysis, and confocal microscopy were used to define CNS vascular permeability. Finally, the open field behavior test was used to assess locomotor activity of mice following immune-mediated BBB disruption. Perforin-null mice had negligible CNS vascular permeability. Perforin-WT mice have extensive CNS vascular permeability. Interestingly, perforin-heterozygous mice had an intermediate level of CNS vascular permeability as measured by both gadolinium-enhanced T1-weighted MRI and fibrinogen leakage in the brain parenchyma. Differences in BBB disruption were not a result of increased CNS immune infiltrate. Additionally, TMEV was controlled in a perforin dose-dependent manner. Furthermore, a single perforin allele is sufficient to induce locomotor deficit during immune-mediated BBB disruption. Perforin modulates BBB disruption in a dose-dependent manner. This study demonstrates a potentially advantageous role for decreased perforin expression in reducing BBB disruption. This study also provides insight into the effect SNVs in a single perforin allele could have on functional deficit in neurological disease.

Neuroimmunological Blood Brain Barrier Opening in Experimental Cerebral Malaria

PubMed Central

Baer, Kerstin; Mikolajczak, Sebastian A.; Kappe, Stefan H. I.; Frevert, Ute

2012-01-01

Plasmodium falciparum malaria is responsible for nearly one million annual deaths worldwide. Because of the difficulty in monitoring the pathogenesis of cerebral malaria in humans, we conducted a study in various mouse models to better understand disease progression in experimental cerebral malaria (ECM). We compared the effect on the integrity of the blood brain barrier (BBB) and the histopathology of the brain of P. berghei ANKA, a known ECM model, P. berghei NK65, generally thought not to induce ECM, P. yoelii 17XL, originally reported to induce human cerebral malaria-like histopathology, and P. yoelii YM. As expected, P. berghei ANKA infection caused neurological signs, cerebral hemorrhages, and BBB dysfunction in CBA/CaJ and Swiss Webster mice, while Balb/c and A/J mice were resistant. Surprisingly, PbNK induced ECM in CBA/CaJ mice, while all other mice were resistant. P. yoelii 17XL and P. yoelii YM caused lethal hyperparasitemia in all mouse strains; histopathological alterations, BBB dysfunction, or neurological signs were not observed. Intravital imaging revealed that infected erythrocytes containing mature parasites passed slowly through capillaries making intimate contact with the endothelium, but did not arrest. Except for relatively rare microhemorrhages, mice with ECM presented no obvious histopathological alterations that would explain the widespread disruption of the BBB. Intravital imaging did reveal, however, that postcapillary venules, but not capillaries or arterioles, from mice with ECM, but not hyperparasitemia, exhibit platelet marginalization, extravascular fibrin deposition, CD14 expression, and extensive vascular leakage. Blockage of LFA-1 mediated cellular interactions prevented leukocyte adhesion, vascular leakage, neurological signs, and death from ECM. The endothelial barrier-stabilizing mediators imatinib and FTY720 inhibited vascular leakage and neurological signs and prolonged survival to ECM. Thus, it appears that neurological signs and coma in ECM are due to regulated opening of paracellular-junctional and transcellular-vesicular fluid transport pathways at the neuroimmunological BBB. PMID:23133375

Intracarotid tumor necrosis factor-alpha administration increases the blood-brain barrier permeability in cerebral cortex of the newborn pig: quantitative aspects of double-labelling studies and confocal laser scanning analysis.

PubMed

Abraham, C S; Deli, M A; Joo, F; Megyeri, P; Torpier, G

1996-04-19

Tumor necrosis factor-alpha (TNF-alpha) plays a crucial role in the pathogenesis of the central nervous system infections. The aim of the present study was to analyze quantitatively the changes in the blood-brain barrier (BBB) permeability after the intracarotid injection of TNF-alpha. Recombinant human TNF-alpha was injected into the left internal carotid artery of anesthetized newborn pigs (n = 48) in the doses of 0, 1000, 10 000 and 100 000 IU, respectively. Before, as well as 1, 2, 4, 8, and 16 h after the challenge, the extravasation of a small (sodium fluorescein (SF), mw 376), and a large (Evan's blue-albumin (EBA), mw 67 000) tracer was determined concomitantly by spectrophotometry in the cerebral cortex of the animals. There was a time- and dose-dependent increase in BBB permeability both for SF and EBA; however, significant (P < 0.05) BBB opening for albumin only developed 2 h after the challenge. In the morphological study the same excitable tracers, identical experimental protocol and groups were used. Cryostat sections of brain tissue were viewed for optical sectioning with a confocal laser scanning microscope equipped with an argon/krypton ion laser. A diffuse BBB opening for SF and a moderate perivascular extravasation for EBA were found in the cortices of TNF-alpha-treated animals. We conclude that significant increases in intravascular TNF-alpha-concentration during neonatal infections may result in vasogenic brain edema formation.

Etoposide-induced blood-brain barrier disruption. Effect of drug compared with that of solvents.

PubMed

Spigelman, M K; Zappulla, R A; Johnson, J; Goldsmith, S J; Malis, L I; Holland, J F

1984-10-01

The intracarotid infusion of the anti-neoplastic compound, etoposide, has been shown to exert a dose-dependent effect on blood-brain barrier (BBB) permeability. Etoposide, however, is formulated in a complex solvent solution containing alcohol, Tween 80, polyethylene glycol 300, and citric acid. To investigate the contribution of the solvent solution to BBB disruption, the authors studied Sprague-Dawley rats after the internal carotid artery infusion of the solvent solution with and without the addition of etoposide. Experiments were performed at four doses of drug and/or solvent. Disruption of the BBB was evaluated qualitatively by the appearance of the systemically administered dye, Evans blue, in the cerebral hemispheres and quantitatively by the ratio of gamma counts of the technetium-labeled chelate of diethylenetriaminepentaacetic acid (99mTc-DTPA) in the ipsilateral:contralateral hemisphere. Significant barrier opening was obtained in all four groups of animals infused with solvent plus etoposide. In the corresponding groups of rats infused with the solvent solution alone, BBB disruption was markedly lower. Only in the group infused with the largest dose of solvent was the hemispheric ratio of 99mTc-DTPA significantly different from saline-infused animals. Each of the groups with solvent plus etoposide had 99mTc-DTPA ratios significantly different from the control group. Intracarotid infusion and subsequent BBB disruption were well tolerated by the animals receiving either solvent alone or solvent and etoposide. Disruption of the BBB secondary to the intracarotid infusion of etoposide is primarily caused by the drug itself and not by the solvent solution.

Impairment of blood brain barrier is related with the neuroinflammation induced peripheral immune status in intracerebroventricular colchicine injected rats: An experimental study with mannitol.

PubMed

Sil, Susmita; Ghosh, Arijit; Ghosh, Tusharkanti

2016-09-01

The neurodegeneration in AD patients may be associated with changes of peripheral immune responses. Some peripheral immune responses are altered due to neuroinflammation in colchicine induced AD (cAD) rats. The leaky blood brain barrier (BBB) in cAD-rats may be involved in inducing peripheral inflammation, though there is no report in this regard. Therefore, the present study was designed to investigate the role of BBB in cADrats by altering the BBB in a time dependent manner with injection (i.v.) of mannitol (BBB opener). The inflammatory markers in the brain and serum along with the peripheral immune responses were measured after 30 and 60min of mannitol injection in cAD rats. The results showed higher inflammatory markers in the hippocampus and serum along with alterations in peripheral immune parameters in cAD rats. Although the hippocampal inflammatory markers did not further change after mannitol injection in cAD rats, the serum inflammatory markers and peripheral immune responses were altered and these changes were greater after 60min than that of 30min of mannitol injection. The present study shows that the peripheral immune responses in cAD rats after 30 and 60min of mannitol injection are related to magnitude of impairment of BBB in these conditions. It can be concluded from this study that impairment of BBB in cAD rats is related to the changes of peripheral immune responses observed in that condition. Copyright © 2016 Elsevier B.V. All rights reserved.

Altered blood-brain barrier permeability and its effect on the distribution of Evans blue and sodium fluorescein in the rat brain applied by intracarotid injection.

PubMed

Kozler, P; Pokorný, J

2003-01-01

The aim was to study the blood-brain permeability according to the distribution in the rat brain of Evans blue (EB) and sodium fluorescein (NaFl) administered by an intracarotid injection. Eighteen animals were divided into six groups according to the state of the blood-brain barrier (BBB) at the moment when the dyes were being applied. In the first two groups, the BBB was intact, in groups 3 and 4 the barrier had been opened osmotically prior to the application of the dyes, and in groups 5 and 6 a cellular edema was induced by hyperhydration before administration of the dyes. The intracellular and extracellular distribution of the dyes was studied by fluorescence microscopy. The histological picture thus represented the morphological correlate of the way BBB permeability had been changed before the application of the dyes.

Safe and stable noninvasive focal gene delivery to the mammalian brain following focused ultrasound.

PubMed

Stavarache, Mihaela A; Petersen, Nicholas; Jurgens, Eric M; Milstein, Elizabeth R; Rosenfeld, Zachary B; Ballon, Douglas J; Kaplitt, Michael G

2018-04-27

OBJECTIVE Surgical infusion of gene therapy vectors has provided opportunities for biological manipulation of specific brain circuits in both animal models and human patients. Transient focal opening of the blood-brain barrier (BBB) by MR-guided focused ultrasound (MRgFUS) raises the possibility of noninvasive CNS gene therapy to target precise brain regions. However, variable efficiency and short follow-up of studies to date, along with recent suggestions of the potential for immune reactions following MRgFUS BBB disruption, all raise questions regarding the viability of this approach for clinical translation. The objective of the current study was to evaluate the efficiency, safety, and long-term stability of MRgFUS-mediated noninvasive gene therapy in the mammalian brain. METHODS Focused ultrasound under the control of MRI, in combination with microbubbles consisting of albumin-coated gas microspheres, was applied to rat striatum, followed by intravenous infusion of an adeno-associated virus serotype 1/2 (AAV1/2) vector expressing green fluorescent protein (GFP) as a marker. Following recovery, animals were followed from several hours up to 15 months. Immunostaining for GFP quantified transduction efficiency and stability of expression. Quantification of neuronal markers was used to determine histological safety over time, while inflammatory markers were examined for evidence of immune responses. RESULTS Transitory disruption of the BBB by MRgFUS resulted in efficient delivery of the AAV1/2 vector to the targeted rodent striatum, with 50%-75% of striatal neurons transduced on average. GFP transgene expression appeared to be stable over extended periods of time, from 2 weeks to 6 months, with evidence of ongoing stable expression as long as 16 months in a smaller cohort of animals. No evidence of substantial toxicity, tissue injury, or neuronal loss was observed. While transient inflammation from BBB disruption alone was noted for the first few days, consistent with prior observations, no evidence of brain inflammation was observed from 2 weeks to 6 months following MRgFUS BBB opening, despite delivery of a virus and expression of a foreign protein in target neurons. CONCLUSIONS This study demonstrates that transitory BBB disruption using MRgFUS can be a safe and efficient method for site-specific delivery of viral vectors to the brain, raising the potential for noninvasive focal human gene therapy for neurological disorders.

Lipopolysaccharide precipitates hepatic encephalopathy and increases blood-brain barrier permeability in mice with acute liver failure.

PubMed

Chastre, Anne; Bélanger, Mireille; Nguyen, Bich N; Butterworth, Roger F

2014-03-01

Acute liver failure (ALF) is frequently complicated by infection leading to precipitation of central nervous system complications such as hepatic encephalopathy (HE) and increased mortality. There is evidence to suggest that when infection occurs in ALF patients, the resulting pro-inflammatory mechanisms may be amplified that could, in turn, have a major impact on blood-brain barrier (BBB) function. The aim of this study was to investigate the role of endotoxemia on the progression of encephalopathy in relation to BBB permeability during ALF. Adult male C57-BL6 mice with ALF resulting from azoxymethane-induced toxic liver injury were administered trace amounts of the endotoxin component lipopolysaccharide (LPS). Effects on the magnitude of the systemic inflammatory response, liver pathology and BBB integrity were measured as a function of progression of HE, defined as time to loss of corneal reflex (coma). Lipopolysaccharide caused additional two- to seven-fold (P < 0.001) increases in circulating pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), worsening liver pathology and associated increases of circulating transaminases as well as increased hyperammonaemia consistent with a further loss of viable hepatocytes. LPS treatment of ALF mice led to a rapid precipitation of hepatic coma and the BBB became permeable to the 25-kDa protein immunoglobulin G (IgG). This extravasation of IgG was accompanied by ignificant up-regulation of matrix metalloproteinase-9 (MMP-9), an endopeptidase known to modulate opening of the BBB in a wide range of neurological disorders. These findings represent the first direct evidence of inflammation-related BBB permeability changes in ALF. © 2013 John Wiley & Sons A/S. Publishing by John Wiley & Sons Ltd.

Cooling treatment transiently increases the permeability of brain capillary endothelial cells through translocation of claudin-5.

PubMed

Inamura, Akinori; Adachi, Yasuhiro; Inoue, Takao; He, Yeting; Tokuda, Nobuko; Nawata, Takashi; Shirao, Satoshi; Nomura, Sadahiro; Fujii, Masami; Ikeda, Eiji; Owada, Yuji; Suzuki, Michiyasu

2013-08-01

The blood-brain-barrier (BBB) is formed by different cell types, of which brain microvascular endothelial cells are major structural constituents. The goal of this study was to examine the effects of cooling on the permeability of the BBB with reference to tight junction formation of brain microendothelial cells. The sensorimotor cortex above the dura mater in adult male Wistar rats was focally cooled to a temperature of 5 °C for 1 h, then immunostaining for immunoglobulin G (IgG) was performed to evaluate the permeability of the BBB. Permeability produced by cooling was also evaluated in cultured murine brain endothelial cells (bEnd3) based on measurement of trans-epithelial electric resistance (TEER). Immunocytochemistry and Western blotting of proteins associated with tight junctions in bEnd3 were performed to determine protein distribution before and after cooling. After focal cooling of the rat brain cortex, diffuse immunostaining for IgG was observed primarily around the small vasculature and in the extracellular spaces of parenchyma of the cortex. In cultured bEnd3, TEER significantly decreased during cooling (15 °C) and recovered to normal levels after rewarming to 37 °C. Immunocytochemistry and Western blotting showed that claudin-5, a critical regulatory protein for tight junctions, was translocated from the membrane to the cytoplasm after cooling in cultured bEnd3 cells. These results suggest that focal brain cooling may open the BBB transiently through an effect on tight junctions of brain microendothelial cells, and that therapeutically this approach may allow control of BBB function and drug delivery through the BBB.

Neurovascular unit impairment in early Alzheimer's disease measured with magnetic resonance imaging.

PubMed

van de Haar, Harm J; Jansen, Jacobus F A; van Osch, Matthias J P; van Buchem, Mark A; Muller, Majon; Wong, Sau May; Hofman, Paul A M; Burgmans, Saartje; Verhey, Frans R J; Backes, Walter H

2016-09-01

The neurovascular unit, which protects neuronal cells and supplies them with essential molecules, plays an important role in the pathophysiology of Alzheimer's Disease (AD). The aim of this study was to noninvasively investigate 2 linked functional elements of the neurovascular unit, blood-brain barrier (BBB) permeability and cerebral blood flow (CBF), in patients with early AD and healthy controls. Therefore, both dynamic contrast-enhanced magnetic resonance imaging and arterial spin labeling magnetic resonance imaging were applied to measure BBB permeability and CBF, respectively. The patients with early AD showed significantly lower CBF and local blood volume in the gray matter, compared with controls. In the patients, we also found that a reduction in CBF is correlated with an increase in leakage rate. This finding supports the hypothesis that neurovascular damage, and in particular impairment of the neurovascular unit constitutes the pathophysiological link between CBF reduction and BBB impairment in AD. Copyright © 2016 Elsevier Inc. All rights reserved.

Novel Method for Analyzing Locomotor Ability after Spinal Cord Injury in Rats: Technical Note

PubMed Central

Shinozaki, Munehisa; Yasuda, Akimasa; Nori, Satoshi; Saito, Nobuhito; Toyama, Yoshiaki; Okano, Hideyuki; Nakamura, Masaya

2013-01-01

In the research for the treatment of spinal cord injury (SCI), the evaluation of motor function in model rats must be as objective, noninvasive, and ethical as possible. The maximum speed and acceleration of a mouse measured using a SCANET system were previously reported to vary significantly according to severity of SCI. In the present study, the motor performance of SCI model rats was examined with SCANET and assessed for Basso-Beattie-Bresnahan (BBB) score to determine the usefulness of the SCANET system in evaluating functional recovery after SCI. Maximum speed and acceleration within the measurement period correlated significantly with BBB scores. Furthermore, among several phased kinematic factors used in BBB scores, the capability of “plantar stepping” was associated with a drastic increase in maximum speed and acceleration after SCI. Therefore, evaluation of maximum speed and acceleration using a SCANET system is a useful method for rat models of SCI and can complement open field scoring scales. PMID:24097095

Focused ultrasound delivery of Raman nanoparticles across the blood-brain barrier: potential for targeting experimental brain tumors.

PubMed

Diaz, Roberto Jose; McVeigh, Patrick Z; O'Reilly, Meaghan A; Burrell, Kelly; Bebenek, Matthew; Smith, Christian; Etame, Arnold B; Zadeh, Gelareh; Hynynen, Kullervo; Wilson, Brian C; Rutka, James T

2014-07-01

Spectral mapping of nanoparticles with surface enhanced Raman scattering (SERS) capability in the near-infrared range is an emerging molecular imaging technique. We used magnetic resonance image-guided transcranial focused ultrasound (TcMRgFUS) to reversibly disrupt the blood-brain barrier (BBB) adjacent to brain tumor margins in rats. Glioma cells were found to internalize SERS capable nanoparticles of 50nm or 120nm physical diameter. Surface coating with anti-epidermal growth factor receptor antibody or non-specific human immunoglobulin G, resulted in enhanced cell uptake of nanoparticles in-vitro compared to nanoparticles with methyl terminated 12-unit polyethylene glycol surface. BBB disruption permitted the delivery of SERS capable spherical 50 or 120nm gold nanoparticles to the tumor margins. Thus, nanoparticles with SERS imaging capability can be delivered across the BBB non-invasively using TcMRgFUS and have the potential to be used as optical tracking agents at the invasive front of malignant brain tumors. This study demonstrates the use of magnetic resonance image-guided transcranial focused ultrasound to open the BBB and enable spectral mapping of nanoparticles with surface enhanced Raman scattering (SERS)-based molecular imaging for experimental tumor tracking. Copyright © 2014 Elsevier Inc. All rights reserved.

Delivery of Chemotherapeutics Across the Blood–Brain Barrier: Challenges and Advances

PubMed Central

Doolittle, Nancy D.; Muldoon, Leslie L.; Culp, Aliana Y.; Neuwelt, Edward A.

2017-01-01

The blood–brain barrier (BBB) limits drug delivery to brain tumors. We utilize intraarterial infusion of hyperosmotic mannitol to reversibly open the BBB by shrinking endothelial cells and opening tight junctions between the cells. This approach transiently increases the delivery of chemotherapy, antibodies, and nanoparticles to brain. Our preclinical studies have optimized the BBB disruption (BBBD) technique and clinical studies have shown its safety and efficacy. The delivery of methotrexate-based chemotherapy in conjunction with BBBD provides excellent outcomes in primary central nervous system lymphoma (PCNSL) including stable or improved cognitive function in survivors a median of 12 years (range 2–26 years) after diagnosis. The addition of rituximab to chemotherapy with BBBD for PCNSL can be safely accomplished with excellent overall survival. Our translational studies of thiol agents to protect against platinum-induced toxicities led to the development of a two-compartment model in brain tumor patients. We showed that delayed high-dose sodium thiosulfate protects against carboplatin-induced hearing loss, providing the framework for large cooperative group trials of hearing chemoprotection. Neuroimaging studies have identified that ferumoxytol, an iron oxide nanoparticle blood pool agent, appears to be a superior contrast agent to accurately assess therapy-induced changes in brain tumor vasculature, in brain tumor response to therapy, and in differentiating central nervous system lesions with inflammatory components. This chapter reviews the breakthroughs, challenges, and future directions for BBBD. PMID:25307218

Transcranial Cavitation Detection in Primates during Blood-Brain Barrier Opening – A Performance Assessment Study

PubMed Central

Wu, Shih-Ying; Tung, Yao-Sheng; Marquet, Fabrice; Downs, Matthew Eric; Sanchez, Carlos Sierra; Chen, Cherry Chen; Ferrera, Vincent

2014-01-01

Focused ultrasound (FUS) has been shown promise in treating the brain locally and noninvasively. Transcranial passive cavitation detection (PCD) provides methodology of monitoring the treatment in real time, while the skull effects remain a major challenge for its translation to the clinic. In this study, we investigated the sensitivity, reliability, and limitations of PCD through primate (macaque and human) skulls in vitro. The results were further correlated with the in vivo macaque studies including the transcranial PCD calibration and real-time monitoring of BBB opening, with magnetic resonance imaging assessing the opening and safety. The stable cavitation doses using harmonics (SCDh) and ultraharmonics (SCDu), the inertial cavitation dose (ICD), and the cavitation signal-to-noise ratio (SNR) were quantified based on the PCD signals. Results showed that through the macaque skull the pressure threshold for detecting the SCDh remained the same as without the skull in place, while it increased for the SCDu and ICD; through the human skull, it increased for all cavitation doses. The transcranial PCD was found reliable both in vitro and in vivo when the transcranial cavitation SNR exceeded the 1-dB detection limit through the in vitro macaque (attenuation: 4.92 dB/mm) and human (attenuation: 7.33 dB/mm) skull. In addition, using long pulses enabled reliable PCD monitoring and facilitate BBB opening at low pressures. The in vivo results showed that the SCDh became detectable at pressures as low as 100 kPa; the ICD, at 250 kPa while it could occur at lower pressures; the SCDu, at 700 kPa and was less reliable at lower pressures. Real-time monitoring of PCD was further implemented during BBB opening, with successful and safe opening achieved at 250–600 kPa in both the thalamus and the putamen. In conclusion, this study shows that transcranial PCD in macaques in vitro and in vivo as well as humans in vitro is reliable by improving the cavitation SNR beyond the 1-dB detection limit. PMID:24859660

The effect of monascin on hematoma clearance and edema after intracerebral hemorrhage in rats.

PubMed

Wang, Juan; Wang, Gaiqing; Yi, Jinying; Xu, Yi; Duan, Shuna; Li, Tong; Sun, Xin-Gang; Dong, Liang

2017-09-01

Intracerebral hemorrhage (ICH) is a particularly devastating form of stroke with high mortality and morbidity. Hematomas are the primary cause of neurologic deficits associated with ICH. The products of hematoma are recognized as neurotoxins and the main contributors to edema formation and tissue damage after ICH. Finding a means to efficiently promote absorption of hematoma is a novel clinical challenge for ICH. Peroxisome proliferator-activated receptor gamma (PPARγ) and nuclear factor erythroid 2-related factor 2 (Nrf2), had been shown that, can take potential roles in the endogenous hematoma clearance. However, monascin, a novel natural Nrf2 activator with PPARγ agonist, has not been reported to play a role in ICH. This study was designed to evaluate the effect of monascin on neurological deficits, hematoma clearance and edema extinction in a model of ICH in rats. 164 adult male Sprague-Dawley (SD) rats were randomly divided into sham; vehicle; monascin groups with low dosages (1mg/kg/day), middle dosages (5mg/kg/day) and high dosages (10mg/kg/day) respectively. Animals were euthanized at 1, 3 and 7days following neurological evaluation after surgery. We examined the effect of monascin on the brain water contents, blood brain barrier (BBB) permeability and hemoglobin levels, meanwhile reassessed the volume of hematoma and edema around the hematoma by Magnetic Resonance Imaging (MRI) in each group. The high dosage of monascin significantly improved neurological deficits, reduced the volume of hematoma in 1-7days after ICH, decreased BBB permeability and edema formation in 1-3days following ICH. Our study demonstrated that the high dosage of monascin played a neuroprotective role in ICH through reducing BBB permeability, edema and hematoma volume. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimization of Evans blue quantitation in limited rat tissue samples

PubMed Central

Wang, Hwai-Lee; Lai, Ted Weita

2014-01-01

Evans blue dye (EBD) is an inert tracer that measures plasma volume in human subjects and vascular permeability in animal models. Quantitation of EBD can be difficult when dye concentration in the sample is limited, such as when extravasated dye is measured in the blood-brain barrier (BBB) intact brain. The procedure described here used a very small volume (30 µl) per sample replicate, which enabled high-throughput measurements of the EBD concentration based on a standard 96-well plate reader. First, ethanol ensured a consistent optic path length in each well and substantially enhanced the sensitivity of EBD fluorescence spectroscopy. Second, trichloroacetic acid (TCA) removed false-positive EBD measurements as a result of biological solutes and partially extracted EBD into the supernatant. Moreover, a 1:2 volume ratio of 50% TCA ([TCA final] = 33.3%) optimally extracted EBD from the rat plasma protein-EBD complex in vitro and in vivo, and 1:2 and 1:3 weight-volume ratios of 50% TCA optimally extracted extravasated EBD from the rat brain and liver, respectively, in vivo. This procedure is particularly useful in the detection of EBD extravasation into the BBB-intact brain, but it can also be applied to detect dye extravasation into tissues where vascular permeability is less limiting. PMID:25300427

Optimization of Evans blue quantitation in limited rat tissue samples

NASA Astrophysics Data System (ADS)

Wang, Hwai-Lee; Lai, Ted Weita

2014-10-01

Evans blue dye (EBD) is an inert tracer that measures plasma volume in human subjects and vascular permeability in animal models. Quantitation of EBD can be difficult when dye concentration in the sample is limited, such as when extravasated dye is measured in the blood-brain barrier (BBB) intact brain. The procedure described here used a very small volume (30 µl) per sample replicate, which enabled high-throughput measurements of the EBD concentration based on a standard 96-well plate reader. First, ethanol ensured a consistent optic path length in each well and substantially enhanced the sensitivity of EBD fluorescence spectroscopy. Second, trichloroacetic acid (TCA) removed false-positive EBD measurements as a result of biological solutes and partially extracted EBD into the supernatant. Moreover, a 1:2 volume ratio of 50% TCA ([TCA final] = 33.3%) optimally extracted EBD from the rat plasma protein-EBD complex in vitro and in vivo, and 1:2 and 1:3 weight-volume ratios of 50% TCA optimally extracted extravasated EBD from the rat brain and liver, respectively, in vivo. This procedure is particularly useful in the detection of EBD extravasation into the BBB-intact brain, but it can also be applied to detect dye extravasation into tissues where vascular permeability is less limiting.

Tissue inhibitor of matrix metalloproteinases-1 loaded poly(lactic-co-glycolic acid) nanoparticles for delivery across the blood–brain barrier

PubMed Central

Chaturvedi, Mayank; Molino, Yves; Sreedhar, Bojja; Khrestchatisky, Michel; Kaczmarek, Leszek

2014-01-01

Aim The aim of this study was to develop poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) for delivery of a protein – tissue inhibitor of matrix metalloproteinases 1 (TIMP-1) – across the blood–brain barrier (BBB) to inhibit deleterious matrix metalloproteinases (MMPs). Materials and methods The NPs were formulated by multiple-emulsion solvent-evaporation, and for enhancing BBB penetration, they were coated with polysorbate 80 (Ps80). We compared Ps80-coated and uncoated NPs for their toxicity, binding, and BBB penetration on primary rat brain capillary endothelial cell cultures and the rat brain endothelial 4 cell line. These studies were followed by in vivo studies for brain delivery of these NPs. Results Results showed that neither Ps80-coated nor uncoated NPs caused significant opening of the BBB, and essentially they were nontoxic. NPs without Ps80 coating had more binding to endothelial cells compared to Ps80-coated NPs. Penetration studies showed that TIMP-1 NPs + Ps80 had 11.21%±1.35% penetration, whereas TIMP-1 alone and TIMP-1 NPs without Ps80 coating did not cross the endothelial monolayer. In vivo studies indicated BBB penetration of intravenously injected TIMP-1 NPs + Ps80. Conclusion The study demonstrated that Ps80 coating of NPs does not cause significant toxic effects to endothelial cells and that it can be used to enhance the delivery of protein across endothelial cell barriers, both in vitro and in vivo. PMID:24531257

Neuroprotective effect of combined ultrasound and microbubbles in a rat model of middle cerebral artery infarction

NASA Astrophysics Data System (ADS)

Fatar, M.; Griebe, M.; Stroick, M.; Kern, R.; Hennerici, M.; Meairs, S.

2005-03-01

Ultrasound-mediated microbubble thrombolysis (UMT) was performed in a middle cerebral artery occlusion model in rats to evaluate possible effects upon brain infarct volume, apoptosis, IL-6 and TNF-alpha levels, and disruption of the blood-brain barrier (BBB). The results show that infarct volume was significantly reduced (p<0.04) in the microbubble + ultrasound (MB + US) group as compared to control animals. The levels of IL-6 and TNF-alpha concentrations, as markers of tissue damage, were not significantly different. In trypan blue treated animals, no additional BBB disruption was observed for the UMT group. Likewise, there was no increase in apoptotic cell death outside the infarction area in animals treated with MB + US. The results demonstrate that UMT does not have a harmful effect upon ischemic stroke in a middle cerebral artery occlusion model of the rat. The significant reduction in brain infarction following insonation with ultrasound and microbubbles suggests a novel neuroprotective effect in ischemic stroke.

Carotid Artery Stenting and Blood-Brain Barrier Permeability in Subjects with Chronic Carotid Artery Stenosis.

PubMed

Szarmach, Arkadiusz; Halena, Grzegorz; Kaszubowski, Mariusz; Piskunowicz, Maciej; Studniarek, Michal; Lass, Piotr; Szurowska, Edyta; Winklewski, Pawel J

2017-05-08

Failure of the blood-brain barrier (BBB) is a critical event in the development and progression of diseases such as acute ischemic stroke, chronic ischemia or small vessels disease that affect the central nervous system. It is not known whether BBB breakdown in subjects with chronic carotid artery stenosis can be restrained with postoperative recovery of cerebral perfusion. The aim of the study was to assess the short-term effect of internal carotid artery stenting on basic perfusion parameters and permeability surface area-product (PS) in such a population. Forty subjects (23 males) with stenosis of >70% within a single internal carotid artery and neurological symptoms who underwent a carotid artery stenting procedure were investigated. Differences in the following computed tomography perfusion (CTP) parameters were compared before and after surgery: global cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP) and PS. PS acquired by CTP is used to measure the permeability of the BBB to contrast material. In all baseline cases, the CBF and CBV values were low, while MTT and TTP were high on both the ipsi- and contralateral sides compared to reference values. PS was approximately twice the normal value. CBF was higher (+6.14%), while MTT was lower (-9.34%) on the contralateral than on the ipsilateral side. All perfusion parameters improved after stenting on both the ipsilateral (CBF +22.66%; CBV +18.98%; MTT -16.09%, TTP -7.62%) and contralateral (CBF +22.27%, CBV +19.72%, MTT -14.65%, TTP -7.46%) sides. PS decreased by almost half: ipsilateral -48.11%, contralateral -45.19%. The decline in BBB permeability was symmetrical on the ipsi- and contralateral sides to the stenosis. Augmented BBB permeability can be controlled by surgical intervention in humans.

Blood-brain barrier leakage after status epilepticus in rapamycin-treated rats I: Magnetic resonance imaging.

PubMed

van Vliet, Erwin A; Otte, Willem M; Wadman, Wytse J; Aronica, Eleonora; Kooij, Gijs; de Vries, Helga E; Dijkhuizen, Rick M; Gorter, Jan A

2016-01-01

The mammalian target of rapamycin (mTOR) pathway has received increasing attention as a potential antiepileptogenic target. Treatment with the mTOR inhibitor rapamycin after status epilepticus reduces the development of epilepsy in a rat model. To study whether rapamycin mediates this effect via restoration of blood-brain barrier (BBB) dysfunction, contrast-enhanced magnetic resonance imaging (CE-MRI) was used to determine BBB permeability throughout epileptogenesis. Imaging was repeatedly performed until 6 weeks after kainic acid-induced status epilepticus in rapamycin (6 mg/kg for 6 weeks starting 4 h after SE) and vehicle-treated rats, using gadobutrol as contrast agent. Seizures were detected using video monitoring in the week following the last imaging session. Gadobutrol leakage was widespread and extensive in both rapamycin and vehicle-treated epileptic rats during the acute phase, with the piriform cortex and amygdala as the most affected regions. Gadobutrol leakage was higher in rapamycin-treated rats 4 and 8 days after status epilepticus compared to vehicle-treated rats. However, during the chronic epileptic phase, gadobutrol leakage was lower in rapamycin-treated epileptic rats along with a decreased seizure frequency. This was confirmed by local fluorescein staining in the brains of the same rats. Total brain volume was reduced by this rapamycin treatment regimen. The initial slow recovery of BBB function in rapamycin-treated epileptic rats indicates that rapamycin does not reduce seizure activity by a gradual recovery of BBB integrity. The reduced BBB leakage during the chronic phase, however, could contribute to the decreased seizure frequency in post-status epilepticus rats treated with rapamycin. Furthermore, the data show that CE-MRI (using step-down infusion with gadobutrol) can be used as biomarker for monitoring the effect of drug therapy in rats. Wiley Periodicals, Inc. © 2015 International League Against Epilepsy.

Revisiting atenolol as a low passive permeability marker.

PubMed

Chen, Xiaomei; Slättengren, Tim; de Lange, Elizabeth C M; Smith, David E; Hammarlund-Udenaes, Margareta

2017-10-31

Atenolol, a hydrophilic beta blocker, has been used as a model drug for studying passive permeability of biological membranes such as the blood-brain barrier (BBB) and the intestinal epithelium. However, the extent of S-atenolol (the active enantiomer) distribution in brain has never been evaluated, at equilibrium, to confirm that no transporters are involved in its transport at the BBB. To assess whether S-atenolol, in fact, depicts the characteristics of a low passive permeable drug at the BBB, a microdialysis study was performed in rats to monitor the unbound concentrations of S-atenolol in brain extracellular fluid (ECF) and plasma during and after intravenous infusion. A pharmacokinetic model was developed, based on the microdialysis data, to estimate the permeability clearance of S-atenolol into and out of brain. In addition, the nonspecific binding of S-atenolol in brain homogenate was evaluated using equilibrium dialysis. The steady-state ratio of unbound S-atenolol concentrations in brain ECF to that in plasma (i.e., K p,uu,brain ) was 3.5% ± 0.4%, a value much less than unity. The unbound volume of distribution in brain (V u, brain ) of S-atenolol was also calculated as 0.69 ± 0.10 mL/g brain, indicating that S-atenolol is evenly distributed within brain parenchyma. Lastly, equilibrium dialysis showed limited nonspecific binding of S-atenolol in brain homogenate with an unbound fraction (f u,brain ) of 0.88 ± 0.07. It is concluded, based on K p,uu,brain being much smaller than unity, that S-atenolol is actively effluxed at the BBB, indicating the need to re-consider S-atenolol as a model drug for passive permeability studies of BBB transport or intestinal absorption.

Correlations between Blood–Brain Barrier Disruption and Neuroinflammation in an Experimental Model of Penetrating Ballistic-Like Brain Injury

PubMed Central

Cartagena, Casandra M.; Lu, Xi-Chun M.; Konopko, Melissa; Dave, Jitendra R.; Tortella, Frank C.; Shear, Deborah A.

2014-01-01

Abstract Blood–brain barrier (BBB) disruption is a pathological hallmark of severe traumatic brain injury (TBI) and is associated with neuroinflammatory events contributing to brain edema and cell death. The goal of this study was to elucidate the profile of BBB disruption after penetrating ballistic-like brain injury (PBBI) in conjunction with changes in neuroinflammatory markers. Brain uptake of biotin-dextran amine (BDA; 3 kDa) and horseradish peroxidase (HRP; 44 kDa) was evaluated in rats at 4 h, 24 h, 48 h, 72 h, and 7 days post-PBBI and compared with the histopathologic and molecular profiles for inflammatory markers. BDA and HRP both displayed a uniphasic profile of extravasation, greatest at 24 h post-injury and which remained evident out to 48 h for HRP and 7 days for BDA. This profile was most closely associated with markers for adhesion (mRNA for intercellular adhesion molecule-1) and infiltration of peripheral granulocytes (mRNA for matrix metalloproteinase-9 [MMP-9] and myeloperoxidase staining). Improvement of BBB dysfunction coincided with increased expression of markers implicated in tissue remodeling and repair. The results of this study reveal a uniphasic and gradient opening of the BBB after PBBI and suggest MMP-9 and resident inflammatory cell activation as candidates for future neurotherapeutic intervention after PBBI. PMID:24138024

The blood-brain barrier: structure, function and therapeutic approaches to cross it.

PubMed

Tajes, Marta; Ramos-Fernández, Eva; Weng-Jiang, Xian; Bosch-Morató, Mònica; Guivernau, Biuse; Eraso-Pichot, Abel; Salvador, Bertrán; Fernàndez-Busquets, Xavier; Roquer, Jaume; Muñoz, Francisco J

2014-08-01

The blood-brain barrier (BBB) is constituted by a specialized vascular endothelium that interacts directly with astrocytes, neurons and pericytes. It protects the brain from the molecules of the systemic circulation but it has to be overcome for the proper treatment of brain cancer, psychiatric disorders or neurodegenerative diseases, which are dramatically increasing as the population ages. In the present work we have revised the current knowledge on the cellular structure of the BBB and the different procedures utilized currently and those proposed to cross it. Chemical modifications of the drugs, such as increasing their lipophilicity, turn them more prone to be internalized in the brain. Other mechanisms are the use of molecular tools to bind the drugs such as small immunoglobulins, liposomes or nanoparticles that will act as Trojan Horses favoring the drug delivery in brain. This fusion of the classical pharmacology with nanotechnology has opened a wide field to many different approaches with promising results to hypothesize that BBB will not be a major problem for the new generation of neuroactive drugs. The present review provides an overview of all state-of-the-art of the BBB structure and function, as well as of the classic strategies and these appeared in recent years to deliver drugs into the brain for the treatment of Central Nervous System (CNS) diseases.

Delivery of chemotherapeutics across the blood-brain barrier: challenges and advances.

PubMed

Doolittle, Nancy D; Muldoon, Leslie L; Culp, Aliana Y; Neuwelt, Edward A

2014-01-01

The blood-brain barrier (BBB) limits drug delivery to brain tumors. We utilize intraarterial infusion of hyperosmotic mannitol to reversibly open the BBB by shrinking endothelial cells and opening tight junctions between the cells. This approach transiently increases the delivery of chemotherapy, antibodies, and nanoparticles to brain. Our preclinical studies have optimized the BBB disruption (BBBD) technique and clinical studies have shown its safety and efficacy. The delivery of methotrexate-based chemotherapy in conjunction with BBBD provides excellent outcomes in primary central nervous system lymphoma (PCNSL) including stable or improved cognitive function in survivors a median of 12 years (range 2-26 years) after diagnosis. The addition of rituximab to chemotherapy with BBBD for PCNSL can be safely accomplished with excellent overall survival. Our translational studies of thiol agents to protect against platinum-induced toxicities led to the development of a two-compartment model in brain tumor patients. We showed that delayed high-dose sodium thiosulfate protects against carboplatin-induced hearing loss, providing the framework for large cooperative group trials of hearing chemoprotection. Neuroimaging studies have identified that ferumoxytol, an iron oxide nanoparticle blood pool agent, appears to be a superior contrast agent to accurately assess therapy-induced changes in brain tumor vasculature, in brain tumor response to therapy, and in differentiating central nervous system lesions with inflammatory components. This chapter reviews the breakthroughs, challenges, and future directions for BBBD. © 2014 Elsevier Inc. All rights reserved.

Amphiphilic HPMA-LMA copolymers increase the transport of Rhodamine 123 across a BBB model without harming its barrier integrity.

PubMed

Hemmelmann, Mirjam; Metz, Verena V; Koynov, Kaloian; Blank, Kerstin; Postina, Rolf; Zentel, Rudolf

2012-10-28

The successful non-invasive treatment of diseases associated with the central nervous system (CNS) is generally limited by poor brain permeability of various developed drugs. The blood-brain barrier (BBB) prevents the passage of therapeutics to their site of action. Polymeric drug delivery systems are promising solutions to effectively transport drugs into the brain. We recently showed that amphiphilic random copolymers based on the hydrophilic p(N-(2-hydroxypropyl)-methacrylamide), pHPMA, possessing randomly distributed hydrophobic p(laurylmethacrylate), pLMA, are able to mediate delivery of domperidone into the brain of mice in vivo. To gain further insight into structure-property relations, a library of carefully designed polymers based on p(HPMA) and p(LMA) was synthesized and tested applying an in vitro BBB model which consisted of human brain microvascular endothelial cells (HBMEC). Our model drug Rhodamine 123 (Rh123) exhibits, like domperidone, a low brain permeability since both substances are recognized by efflux transporters at the BBB. Transport studies investigating the impact of the polymer architecture in relation to the content of hydrophobic LMA revealed that random p(HPMA)-co-p(LMA) having 10mol% LMA is the most auspicious system. The copolymer significantly increased the permeability of Rh123 across the HBMEC monolayer whereas transcytosis of the polymer was very low. Further investigations on the mechanism of transport showed that integrity and barrier function of the BBB model were not harmed by the polymer. According to our results, p(HPMA)-co-p(LMA) copolymers are a promising delivery system for neurological therapeutics and their application might open alternative treatment strategies. Copyright © 2012 Elsevier B.V. All rights reserved.

Pathophysiology of Blood-Brain Barrier in Brain Injury in Cold and Hot Environments: Novel Drug Targets for Neuroprotection.

PubMed

Sharma, Hari Shanker; Muresanu, Dafin F; Lafuente, José V; Nozari, Ala; Patnaik, Ranjana; Skaper, Stephen D; Sharma, Aruna

2016-01-01

The blood-brain barrier (BBB) plays a pivotal role in the maintenance of central nervous system function in health and disease. Thus, in almost all neurodegenerative, traumatic or metabolic insults BBB breakdown occurs, allowing entry of serum proteins into the brain fluid microenvironment with subsequent edema formation and cellular injury. Accordingly, pharmacological restoration of BBB function will lead to neurorepair. However, brain injury which occurs following blast, bullet wounds, or knife injury appears to initiate different sets of pathophysiological responses. Moreover, other local factors at the time of injury such as cold or elevated ambient temperatures could also impact the final outcome. Obviously, drug therapy applied to different kinds of brain trauma occurring at either cold or hot environments may respond differently. This is largely due to the fact that internal defense mechanisms of the brain, gene expression, release of neurochemicals and binding of drugs to specific receptors are affected by external ambient temperature changes. These factors may also affect BBB function and development of edema formation after brain injury. In this review, the effects of seasonal exposure to heat and cold on traumatic brain injury using different models i.e., concussive brain injury and cerebral cortical lesion, on BBB dysfunction in relation to drug therapy are discussed. Our observations clearly suggest that closed head injury and open brain injury are two different entities and the external hot or cold environments affect both of them remarkably. Thus, effective pharmacological therapeutic strategies should be designed with these views in mind, as military personnel often experience blunt or penetrating head injuries in either cold or hot environments.

CORM-A1 prevents blood-brain barrier dysfunction caused by ionotropic glutamate receptor-mediated endothelial oxidative stress and apoptosis.

PubMed

Basuroy, Shyamali; Leffler, Charles W; Parfenova, Helena

2013-06-01

In cerebral microvascular endothelial cells (CMVEC) of newborn pigs, glutamate at excitotoxic concentrations (mM) causes apoptosis mediated by reactive oxygen species (ROS). Carbon monoxide (CO) produced by CMVEC or delivered by a CO-releasing molecule, CORM-A1, has antioxidant properties. We tested the hypothesis that CORM-A1 prevents cerebrovascular endothelial barrier dysfunction caused by glutamate excitotoxicity. First, we identified the glutamate receptors (GluRs) and enzymatic sources of ROS involved in the mechanism of endothelial apoptosis. In glutamate-exposed CMVEC, ROS formation and apoptosis were blocked by rotenone, 2-thenoyltrifluoroacetone (TTFA), and antimycin, indicating that mitochondrial complexes I, II, and III are the major sources of oxidative stress. Agonists of ionotropic GluRs (iGluRs) N-methyl-D-aspartate (NMDA), cis-ACPD, AMPA, and kainate increased ROS production and apoptosis, whereas iGluR antagonists exhibited antiapoptotic properties, suggesting that iGluRs mediate glutamate-induced endothelial apoptosis. The functional consequences of endothelial injury were tested in the model of blood-brain barrier (BBB) composed of CMVEC monolayer on semipermeable membranes. Glutamate and iGluR agonists reduced transendothelial electrical resistance and increased endothelial paracellular permeability to 3-kDa dextran. CORM-A1 exhibited potent antioxidant and antiapoptotic properties in CMVEC and completely prevented BBB dysfunction caused by glutamate and iGluR agonists. Overall, the endothelial component of the BBB is a cellular target for excitotoxic glutamate that, via a mechanism involving a iGluR-mediated activation of mitochondrial ROS production and apoptosis, leads to BBB opening that may be prevented by the antioxidant and antiapoptotic actions of CORMs. Antioxidant CORMs therapy may help preserve BBB functional integrity in neonatal cerebrovascular disease.

Bundle branch block after ablation for Wolff-Parkinson-White syndrome.

PubMed

Fuenmayor A, Abdel J; Rodríguez S, Yenny A

2013-09-20

Bundle branch block (BBB) is a difficult diagnosis in the Wolff-Parkinson-White syndrome (WPW). We investigated the clinical implications of BBB that appears after performing an accessory pathway (AP) ablation. We studied 199 patients with WPW who were submitted to AP ablation. Thirty (15%) exhibited BBB after the ablation. Twenty-two patients had right BBB and 8 had left BBB. Thirteen patients had right-sided AP and 17 had left-sided AP. They were compared with 82 similar patients without BBB after the AP ablation. Among the patients with BBB, 86.66% showed delays in the middle part of the QRS in the ECG recorded before ablation vs. 18.29% of the patients without BBB (p<0.05) (sensitivity 86%, specificity 81%, positive predictive value 67% and negative predictive value 93%). Forty-four percent of the patients with BBB had BBB morphology during orthodromic tachycardia vs. 10% of the patients without BBB (p<0.05) (sensitivity 44%, specificity 89%, positive predictive value 57% and negative predictive value 82%). No relationship was found between AP location and the site of the BBB. Ejection fraction was normal before (0.61 ± 0.03) and upon completion of follow-up (0.61 ± 0.07). BBB disappeared in 95.3% of the patients. Delays in the middle portion of the QRS may predict BBB after AP ablation. BBB after performing AP ablation is frequent, transient, benign, and not related to either the ablation lesion location or progression to structural heart disease. BBB after AP ablation may be related to cardiac memory. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Effect of hyperosmotic solutions on salt excretion and thirst in rats

NASA Technical Reports Server (NTRS)

Schoorlemmer, G. H.; Johnson, A. K.; Thunhorst, R. L.

2000-01-01

We investigated urinary changes and thirst induced by infusion of hyperosmotic solutions in freely moving rats. Intracarotid infusions of 0.3 M NaCl (4 ml/20 min, split between both internal carotid arteries) caused a larger increase in excretion of Na(+) and K(+) than intravenous infusions, indicating that cephalic sensors were involved in the response to intracarotid infusions. Intravenous and intracarotid infusions of hyperosmotic glycerol or urea (300 mM in 150 mM NaCl) had little or no effect, suggesting the sensors were outside the blood-brain barrier (BBB). Intracarotid infusion of hypertonic mannitol (300 mM in 150 mM NaCl) was more effective than intravenous infusion, suggesting that cell volume rather than Na(+) concentration of the blood was critical. Similarly, intracarotid infusion (2 ml/20 min, split between both sides), but not intravenous infusion of hypertonic NaCl or mannitol caused thirst. Hyperosmotic glycerol, infused intravenously or into the carotid arteries, did not cause thirst. We conclude that both thirst and electrolyte excretion depend on a cell volume sensor that is located in the head, but outside the BBB.

Agmatine attenuates brain edema through reducing the expression of aquaporin-1 after cerebral ischemia

PubMed Central

Kim, Jae Hwan; Lee, Yong Woo; Park, Kyung Ah; Lee, Won Taek; Lee, Jong Eun

2010-01-01

Brain edema is frequently shown after cerebral ischemia. It is an expansion of brain volume because of increasing water content in brain. It causes to increase mortality after stroke. Agmatine, formed by the decarboxylation of -arginine by arginine decarboxylase, has been shown to be neuroprotective in trauma and ischemia models. The purpose of this study was to investigate the effect of agmatine for brain edema in ischemic brain damage and to evaluate the expression of aquaporins (AQPs). Results showed that agmatine significantly reduced brain swelling volume 22 h after 2 h middle cerebral artery occlusion in mice. Water content in brain tissue was clearly decreased 24 h after ischemic injury by agmatine treatment. Blood–brain barrier (BBB) disruption was diminished with agmatine than without. The expressions of AQPs-1 and -9 were well correlated with brain edema as water channels, were significantly decreased by agmatine treatment. It can thus be suggested that agmatine could attenuate brain edema by limitting BBB disruption and blocking the accumulation of brain water content through lessening the expression of AQP-1 after cerebral ischemia. PMID:20029450

A dual-targeting nanocarrier based on poly(amidoamine) dendrimers conjugated with transferrin and tamoxifen for treating brain gliomas.

PubMed

Li, Yan; He, Hai; Jia, Xinru; Lu, Wan-Liang; Lou, Jinning; Wei, Yen

2012-05-01

A pH-sensitive dual-targeting drug carrier (G4-DOX-PEG-Tf-TAM) was synthesized with transferrin (Tf) conjugated on the exterior and Tamoxifen (TAM) in the interior of the fourth generation PAMAM dendrimers for enhancing the blood-brain barrier (BBB) transportation and improving the drug accumulation in the glioma cells. It was found that, on average, 7 doxorubicine (DOX) molecules, over 30 PEG(1000) and PEG(2000) chains and one Tf group were bonded on the periphery of each G4 PAMAM dendrimer, while 29 TAM molecules were encapsulated into the interior of per dendrimer. The pH-triggered DOX release was 32% at pH 4.5 and 6% at pH 7.4, indicating a comparatively fast drug release at weak acidic condition and stable state of the carrier at physiological environment. The in vitro assay of the drug transport across the BBB model showed that G4-DOX-PEG-Tf-TAM exhibited higher BBB transportation ability with the transporting ratio of 6.06% in 3 h. The carrier was internalized into C6 glioma cells upon crossing the BBB model by the coactions of TfR-mediated endocytosis and the inhibition effect of TAM to the drug efflux transports. Moreover, it also displayed the in vitro accumulation of DOX in the avascular C6 glioma spheroids made the tumor volume effectively reduced. Copyright © 2012 Elsevier Ltd. All rights reserved.

Protective actions of PJ34, a poly(ADP-ribose)polymerase inhibitor, on the blood-brain barrier after traumatic brain injury in mice.

PubMed

Tao, X; Chen, X; Hao, S; Hou, Z; Lu, T; Sun, M; Liu, B

2015-04-16

Poly(ADP-ribose) polymerase (PARP) is activated by oxidative stress and plays an important role in traumatic brain injury (TBI). The objective of this study was to investigate whether PARP activation participated in the blood-brain barrier (BBB) disruption and edema formation in a mouse model of controlled cortical impact (CCI). N-(6-oxo-5,6-dihydrophenanthridin-2-yl)-N,N-dimethylacetamide (PJ34) (10 mg/kg), a selective PARP inhibitor, was administered intraperitoneally at 5 min and 8 h after experimental CCI. After 6 h and 24 h of CCI, the permeability of the cortical BBB was determined after Evans Blue administration. The water content of the brain was also measured. Treatment with PJ34 markedly attenuated the permeability of the BBB and decreased the brain edema at 6 h and 24 h after CCI. Our data showed the up-regulation of nuclear factor-κB in cytosolic fractions and nuclear fractions in the injured cortex, and these changes were reversed by PJ34. Moreover, PJ34 significantly lessened the activities of myeloperoxidase and the levels of matrix metalloproteinase-9, enhanced the levels of occludin, laminin, collagen IV and integrin β1, reduced neurological deficits, decreased the contusion volume, and attenuated the necrotic and apoptotic neuronal cell death. These data suggest the protective effects of PJ34 on BBB integrity and cell death during acute TBI. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Efficient Blood-Brain Barrier Opening in Primates with Neuronavigation-Guided Ultrasound and Real-Time Acoustic Mapping.

PubMed

Wu, Shih-Ying; Aurup, Christian; Sanchez, Carlos Sierra; Grondin, Julien; Zheng, Wenlan; Kamimura, Hermes; Ferrera, Vincent P; Konofagou, Elisa E

2018-05-22

Brain diseases including neurological disorders and tumors remain under treated due to the challenge to access the brain, and blood-brain barrier (BBB) restricting drug delivery which, also profoundly limits the development of pharmacological treatment. Focused ultrasound (FUS) with microbubbles is the sole method to open the BBB noninvasively, locally, and transiently and facilitate drug delivery, while translation to the clinic is challenging due to long procedure, targeting limitations, or invasiveness of current systems. In order to provide rapid, flexible yet precise applications, we have designed a noninvasive FUS and monitoring system with the protocol tested in monkeys (from in silico preplanning and simulation, real-time targeting and acoustic mapping, to post-treatment assessment). With a short procedure (30 min) similar to current clinical imaging duration or radiation therapy, the achieved targeting (both cerebral cortex and subcortical structures) and monitoring accuracy was close to the predicted 2-mm lower limit. This system would enable rapid clinical transcranial FUS applications outside of the MRI system without a stereotactic frame, thereby benefiting patients especially in the elderly population.

Advancements in nano-enabled therapeutics for neuroHIV management.

PubMed

Kaushik, Ajeet; Jayant, Rahul Dev; Nair, Madhavan

This viewpoint is a global call to promote fundamental and applied research aiming toward designing smart nanocarriers of desired properties, novel noninvasive strategies to open the blood-brain barrier (BBB), delivery/release of single/multiple therapeutic agents across the BBB to eradicate neurohuman immunodeficiency virus (HIV), strategies for on-demand site-specific release of antiretroviral therapy, developing novel nanoformulations capable to recognize and eradicate latently infected HIV reservoirs, and developing novel smart analytical diagnostic tools to detect and monitor HIV infection. Thus, investigation of novel nanoformulations, methodologies for site-specific delivery/release, analytical methods, and diagnostic tools would be of high significance to eradicate and monitor neuroacquired immunodeficiency syndrome. Overall, these developments will certainly help to develop personalized nanomedicines to cure HIV and to develop smart HIV-monitoring analytical systems for disease management.

Non-invasive, neuron-specific gene therapy by focused ultrasound-induced blood-brain barrier opening in Parkinson's disease mouse model.

PubMed

Lin, Chung-Yin; Hsieh, Han-Yi; Chen, Chiung-Mei; Wu, Shang-Rung; Tsai, Chih-Hung; Huang, Chiung-Yin; Hua, Mu-Yi; Wei, Kuo-Chen; Yeh, Chih-Kuang; Liu, Hao-Li

2016-08-10

Focused ultrasound (FUS)-induced with microbubbles (MBs) is a promising technique for noninvasive opening of the blood-brain barrier (BBB) to allow targeted delivery of therapeutic substances into the brain and thus the noninvasive delivery of gene vectors for CNS treatment. We have previously demonstrated that a separated gene-carrying liposome and MBs administration plus FUS exposure can deliver genes into the brain, with the successful expression of the reporter gene and glial cell line-derived neurotrophic factor (GDNF) gene. In this study, we further modify the delivery system by conjugating gene-carrying liposomes with MBs to improve the GDNF gene-delivery efficiency, and to verify the possibility of using this system to perform treatment in the 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced animal disease model. FUS-BBB opening was verified by contrast-enhanced MRI, and GFP gene expression was verified via in vivo imaging system (IVIS). Western blots as well as enzyme-linked immunosorbent assay (ELISA) were conducted to measure protein expression, and immunohistochemistry (IHC) was conducted to test the Tyrosine hydroxylase (TH)-neuron distribution. Dopamine (DA) and its metabolites as well as dopamine active transporter (DAT) were quantitatively analyzed to show dopaminergic neuronal dopamine secretion/activity/metabolism. Motor performance was evaluated by rotarod test weekly. Results demonstrated that the LpDNA-MBs (gene-liposome-MBs) complexes successfully serve as gene carrier and BBB-opening catalyst, and outperformed the separated LpDNA/MBs administration both in terms of gene delivery and expression. TH-positive IHC and measurement of DA and its metabolites DOPAC and HVA confirmed improved neuronal function, and the proposed system also provided the best neuroprotective effect to retard the progression of motor-related behavioral abnormalities. Immunoblotting and histological staining further confirmed the expression of reporter genes in neuronal cells. This study suggests that FUS exposures with the administration of LpDNA-MBs complexes synergistically can serve as an effective gene therapy strategy for MPTP-animal treatment, and may have potential for further application to perform gene therapy for neurodegenerative disease. Copyright © 2016 Elsevier B.V. All rights reserved.

Brainstem blood brain barrier disruption using focused ultrasound: A demonstration of feasibility and enhanced doxorubicin delivery.

PubMed

Alli, Saira; Figueiredo, Carlyn A; Golbourn, Brian; Sabha, Nesrin; Wu, Megan Yijun; Bondoc, Andrew; Luck, Amanda; Coluccia, Daniel; Maslink, Colin; Smith, Christian; Wurdak, Heiko; Hynynen, Kullervo; O'Reilly, Meaghan; Rutka, James T

2018-05-15

Magnetic Resonance Image-guided Focused Ultrasound (MRgFUS) has been used to achieve transient blood brain barrier (BBB) opening without tissue injury. Delivery of a targeted ultrasonic wave causes an interaction between administered microbubbles and the capillary bed resulting in enhanced vessel permeability. The use of MRgFUS in the brainstem has not previously been shown but could provide value in the treatment of tumours such as Diffuse Intrinsic Pontine Glioma (DIPG) where the intact BBB has contributed to the limited success of chemotherapy. Our primary objective was to determine whether the use of MRgFUS in this eloquent brain region could be performed without histological injury and functional deficits. Our secondary objective was to select an effective chemotherapeutic against patient derived DIPG cell lines and demonstrate enhanced brainstem delivery when combined with MRgFUS in vivo. Female Sprague Dawley rats were randomised to one of four groups: 1) Microbubble administration but no MRgFUS treatment; 2) MRgFUS only; 3) MRgFUS + microbubbles; and 4) MRgFUS + microbubbles + cisplatin. Physiological assessment was performed by monitoring of heart and respiratory rates. Motor function and co-ordination were evaluated by Rotarod and grip strength testing. Histological analysis for haemorrhage (H&E), neuronal nuclei (NeuN) and apoptosis (cleaved Caspase-3) was also performed. A drug screen of eight chemotherapy agents was conducted in three patient-derived DIPG cell lines (SU-DIPG IV, SU-DIPG XIII and SU-DIPG XVII). Doxorubicin was identified as an effective agent. NOD/SCID/GAMMA (NSG) mice were subsequently administered with 5 mg/kg of intravenous doxorubicin at the time of one of the following: 1) Microbubbles but no MRgFUS; 2) MRgFUS only; 3) MRgFUS + microbubbles and 4) no intervention. Brain specimens were extracted at 2 h and doxorubicin quantification was conducted using liquid chromatography mass spectrometry (LC/MS). BBB opening was confirmed by contrast enhancement on T1-weighted MR imaging and positive Evans blue staining of the brainstem. Normal cardiorespiratory parameters were preserved. Grip strength and Rotarod testing demonstrating no decline in performance across all groups. Histological analysis showed no evidence of haemorrhage, neuronal loss or increased apoptosis. Doxorubicin demonstrated cytotoxicity against all three cell lines and is known to have poor BBB permeability. Quantities measured in the brainstem of NSG mice were highest in the group receiving MRgFUS and microbubbles (431.5 ng/g). This was significantly higher than in mice who received no intervention (7.6 ng/g). Our data demonstrates both the preservation of histological and functional integrity of the brainstem following MRgFUS for BBB opening and the ability to significantly enhance drug delivery to the region, giving promise to the treatment of brainstem-specific conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of magnolol on cerebral injury and blood brain barrier dysfunction induced by ischemia-reperfusion in vivo and in vitro.

PubMed

Liu, Xiaoyan; Chen, Xiaoling; Zhu, Yuanjun; Wang, Kewei; Wang, Yinye

2017-08-01

Magnolol, a neolignan compound isolated from traditional Chinese medicine Magnolia officinalis, has a potentially therapeutic influence on ischemic stroke. Previous studies have demonstrated that cerebral ischemia-reperfusion (I-R) and blood-brain barrier (BBB) are involved in the pathogeneses of stroke. Therefore, in vivo and in vitro studies were designed to investigate the effects of magnolol on I-R-induced neural injury and BBB dysfunction. In cerebral I-R model of mice, cerebral infarct volumes, brain water content, and the exudation of Evans blue were significantly reduced by intravenous injection with magnolol at the doses of 1.4, 7.0, and 35.0 μg/kg. When primary cultured microglial cells were treated with 1 μg/ml lipopolysaccharide (LPS) plus increasing concentrations of magnolol, ranging from 0.01 to 10 μmol/L, magnolol could statistically inhibit LPS-induced NO release, TNF-α secretion, and expression of p65 subunit of NF-κB in the nucleus of microglial cells. In the media of brain microvascular endothelial cells (BMECs), oxygen and glucose deprivation-reperfusion (OGD-R) could remarkably lead to the elevation of TNF-α and IL-1β levels, while magnolol evidently reversed these effects. In BBB model in vitro, magnolol dose- and time-dependently declined BBB hyperpermeability induced by oxygen and glucose deprivation (OGD), OGD-R, and ephrin-A1 treatment. More importantly, magnolol could obviously inhibit phosphorylation of EphA2 (p-EphA2) not only in ephrin-A1-treated BMECs but also in cerebral I-R model of mice. In contrast to p-EphA2, magnolol significantly increased ZO-1 and occludin levels in BMECs subjected to OGD. Taken together, magnolol can protect neural damage from cerebral ischemia- and OGD-reperfusion, which may be associated with suppressing cerebral inflammation and improving BBB function.

A new descriptor via bio-mimetic chromatography and modeling for the blood brain barrier (Part II).

PubMed

Kouskoura, Maria G; Piteni, Aikaterini I; Markopoulou, Catherine K

2018-05-25

Within the context of drug design methodology for the central nervous system (CNS), a predictive model which can shorten the process of finding new candidate drugs was developed. Therefore, the retention time of 51 molecules which are clinically established to enter the blood brain barrier (BBB), were recorded on two HPLC columns. For this purpose, a lipophilic butyl (C 4 ) stationary phase was used to simulate the behavior of a drug regarding BBB permeability and a zwitterionic-HILIC to simulate blood. The results were plotted as Y variables on two Partial Least Squares (PLS) models, while 25 specific physicochemical properties (significant for lipid bilayers BBB permeation or blood) were used as X descriptors. Both models can be utilized to predict the drugability of a new molecule avoiding needless animal experiments, as well as time and material consuming syntheses. The developed models were validated (R 2  ≥ 0.90, Q 2  ≥ 0.83), and based on the results specific variables were proved to be significant for the studied phenomenon. Additionally, a new factor symbolized as MT was introduced. MT incorporated the experimental results and it was calculated by the fraction of the sum of the retention time of the drug on the two columns (t r(butyl)  + t r(HILIC) ) divided by the molecular volume (V m ) of each analyte. This new descriptor was used as an equivalent to the logarithm of BBB permeability (logBB) and may indicate the ability of a new molecule to act as a candidate drug able to enter the BBB. Comprehending the extend of contribution of several molecular attributes to the in vivo distribution of a drug may enlighten the knowledge on pharmacokinetics and clinical variation, and enable scientists to design more efficient drug molecules. Copyright © 2018 Elsevier B.V. All rights reserved.

Serial block-face scanning electron microscopy applied to study the trafficking of 8D3-coated gold nanoparticles at the blood-brain barrier.

PubMed

Cabezón, Itsaso; Augé, Elisabet; Bosch, Manel; Beckett, Alison J; Prior, Ian A; Pelegrí, Carme; Vilaplana, Jordi

2017-07-01

Due to the physical and physiological properties of the blood-brain barrier (BBB), the transport of neurotherapeutics from blood to brain is still a pharmaceutical challenge. We previously conducted a series of experiments to explore the potential of the anti-transferrin receptor 8D3 monoclonal antibody (mAb) to transport neurotherapeutics across the BBB. In that study, gold nanoparticles (AuNPs) were coated with the 8D3 antibody and administered intravenously to mice. Transmission electron microscopy was used and a two-dimensional (2D) image analysis was performed to detect the AuNPs in the brain capillary endothelial cells (BCECs) and brain parenchyma. In the present work, we determined that serial block-face scanning electron microscopy (SBF-SEM) is a useful tool to study the transcytosis of these AuNPs across the BBB in three dimensions and we, therefore, applied it to gain more knowledge of their transcellular trafficking. The resulting 3D reconstructions provided additional information on the endocytic vesicles containing AuNPs and the endosomal processing that occurs inside BCECs. The passage from 2D to 3D analysis reinforced the trafficking model proposed in the 2D study, and revealed that the vesicles containing AuNPs are significantly larger and more complex than described in our 2D study. We also discuss tradeoffs of using this technique for our application, and conclude that together with other volume electron microscopy imaging techniques, SBF-SEM is a powerful approach that is worth of considering for studies of drug transport across the BBB.

Tariquidar-induced P-glycoprotein inhibition at the rat blood-brain barrier studied with (R)-11C-verapamil and PET.

PubMed

Bankstahl, Jens P; Kuntner, Claudia; Abrahim, Aiman; Karch, Rudolf; Stanek, Johann; Wanek, Thomas; Wadsak, Wolfgang; Kletter, Kurt; Müller, Markus; Löscher, Wolfgang; Langer, Oliver

2008-08-01

The multidrug efflux transporter P-glycoprotein (P-gp) is expressed in high concentrations at the blood-brain barrier (BBB) and is believed to be implicated in resistance to central nervous system drugs. We used small-animal PET and (R)-11C-verapamil together with tariquidar, a new-generation P-gp modulator, to study the functional activity of P-gp at the BBB of rats. To enable a comparison with human PET data, we performed kinetic modeling to estimate the rate constants of radiotracer transport across the rat BBB. A group of 7 Wistar Unilever rats underwent paired (R)-11C-verapamil PET scans at an interval of 3 h: 1 baseline scan and 1 scan after intravenous injection of tariquidar (15 mg/kg, n = 5) or vehicle (n = 2). After tariquidar administration, the distribution volume (DV) of (R)-11C-verapamil was 12-fold higher than baseline (3.68 +/- 0.81 vs. 0.30 +/- 0.08; P = 0.0007, paired t test), whereas the DVs were essentially the same when only vehicle was administered. The increase in DV could be attributed mainly to an increased influx rate constant (K1) of (R)-11C-verapamil into the brain, which was about 8-fold higher after tariquidar. A dose-response assessment with tariquidar provided an estimated half-maximum effect dose of 8.4 +/- 9.5 mg/kg. Our data demonstrate that (R)-11C-verapamil PET combined with tariquidar administration is a promising approach to measure P-gp function at the BBB.

Intracarotid administration of short-chain alkylglycerols for increased delivery of methotrexate to the rat brain.

PubMed

Erdlenbruch, Bernhard; Schinkhof, Claudia; Kugler, Wilfried; Heinemann, Dagmar E H; Herms, Jochen; Eibl, Hansjörg; Lakomek, Max

2003-06-01

1 The intracarotid administration of alkylglycerols has been reported previously by us to be a novel strategy for increased delivery of various chemotherapeutic drugs to the normal brain and brain tumors in rats. 2 Effectiveness and structure-activity relations of the most promising pentyl- and hexylglycerol derivatives have been elucidated in vivo by analyzing the transfer of methotrexate (MTX) across the blood-brain barrier (BBB) in normal rats. The effects were compared with BBB disruption using hypertonic mannitol or intracarotid infusion of bradykinin. Furthermore, toxicity of the alkylglycerols has been studied in long-term experiments. 3 Apart from 1-O-pentyldiglycerol, all alkylglycerols induced a concentration-dependent increase in MTX delivery to the brain varying from 1.1 to more than 300-fold compared to intra-arterial MTX alone. Enhanced barrier permeability rapidly approached baseline values within 5 and 120 min at the latest. Chemical structure, concentration, time schedule of injections and combination of different alkylglycerols were identified as instruments suited to regulate the MTX accumulation within a wide range. Mannitol 1.4 M resulted in very high MTX levels in the brain as observed using the highest concentrations of alkylglycerols. Intracarotid infusion of bradykinin had only a minor effect on the BBB. Using 1-O-pentylglycerol or 2-O-hexyldiglycerol, both cell culture experiments and long-term in vivo analyses including clinical, laboratory and histopathological evaluations revealed no signs of toxicity. 4 In summary, intracarotid short-chain alkylglycerols constitute a very effective and low toxic strategy for transient opening of the BBB to overcome the limited access of cytotoxic drugs to the brain.

Intracarotid administration of short-chain alkylglycerols for increased delivery of methotrexate to the rat brain

PubMed Central

Erdlenbruch, Bernhard; Schinkhof, Claudia; Kugler, Wilfried; Heinemann, Dagmar E H; Herms, Jochen; Eibl, Hansjörg; Lakomek, Max

2003-01-01

The intracarotid administration of alkylglycerols has been reported previously by us to be a novel strategy for increased delivery of various chemotherapeutic drugs to the normal brain and brain tumors in rats. Effectiveness and structure–activity relations of the most promising pentyl- and hexylglycerol derivatives have been elucidated in vivo by analyzing the transfer of methotrexate (MTX) across the blood–brain barrier (BBB) in normal rats. The effects were compared with BBB disruption using hypertonic mannitol or intracarotid infusion of bradykinin. Furthermore, toxicity of the alkylglycerols has been studied in long-term experiments. Apart from 1-O-pentyldiglycerol, all alkylglycerols induced a concentration-dependent increase in MTX delivery to the brain varying from 1.1 to more than 300-fold compared to intra-arterial MTX alone. Enhanced barrier permeability rapidly approached baseline values within 5 and 120 min at the latest. Chemical structure, concentration, time schedule of injections and combination of different alkylglycerols were identified as instruments suited to regulate the MTX accumulation within a wide range. Mannitol 1.4 M resulted in very high MTX levels in the brain as observed using the highest concentrations of alkylglycerols. Intracarotid infusion of bradykinin had only a minor effect on the BBB. Using 1-O-pentylglycerol or 2-O-hexyldiglycerol, both cell culture experiments and long-term in vivo analyses including clinical, laboratory and histopathological evaluations revealed no signs of toxicity. In summary, intracarotid short-chain alkylglycerols constitute a very effective and low toxic strategy for transient opening of the BBB to overcome the limited access of cytotoxic drugs to the brain. PMID:12812991

Targeted Gene Transfer to the Brain via the Delivery of Brain-Penetrating DNA Nanoparticles with Focused Ultrasound

PubMed Central

Mead, Brian P.; Mastorakos, Panagiotis; Suk, Jung Soo; Klibanov, Alexander L.; Hanes, Justin; Price, Richard J.

2016-01-01

Gene therapy holds promise for the treatment of many pathologies of the central nervous system (CNS), including brain tumors and neurodegenerative diseases. However, the delivery of systemically administered gene carriers to the CNS is hindered by both the blood-brain barrier (BBB) and the nanoporous and electrostatically charged brain extracelluar matrix (ECM), which acts as a steric and adhesive barrier. We have previously shown that these physiological barriers may be overcome by, respectively, opening the BBB with MR image-guided focused ultrasound (FUS) and microbubbles and using highly compact “brain penetrating” nanoparticles (BPN) coated with a dense polyethylene glycol corona that prevents adhesion to ECM components. Here, we tested whether this combined approach could be utilized to deliver systemically administered DNA-bearing BPN (DNA-BPN) across the BBB and mediate localized, robust, and sustained transgene expression in the rat brain. Systemically administered DNA-BPN delivered through the BBB with FUS led to dose-dependent transgene expression only in the FUS-treated region that was evident as early as 24 h post administration and lasted for at least 28 days. In the FUS-treated region ~42% of all cells, including neurons and astrocytes, were transfected, while less than 6% were transfected in the contralateral non-FUS treated hemisphere. Importantly, this was achieved without any sign of toxicity or astrocyte activation. We conclude that the image-guided delivery of DNA-BPN with FUS and microbubbles constitutes a safe and non-invasive strategy for targeted gene therapy to the brain. PMID:26732553

Feasibility and Safety of Intra-arterial Pericyte Progenitor Cell Delivery Following Mannitol-Induced Transient Blood-Brain Barrier Opening in a Canine Model.

PubMed

Youn, Sung Won; Jung, Keun-Hwa; Chu, Kon; Lee, Jong-Young; Lee, Soon-Tae; Bahn, Jae-jun; Park, Dong-Kyu; Yu, Jung-Suk; Kim, So-Yun; Kim, Manho; Lee, Sang Kun; Han, Moon-Hee; Roh, Jae-Kyu

2015-01-01

Stem cell therapy is currently being studied with a view to rescuing various neurological diseases. Such studies require not only the discovery of potent candidate cells but also the development of methods that allow optimal delivery of those candidates to the brain tissues. Given that the blood-brain barrier (BBB) precludes cells from entering the brain, the present study was designed to test whether hyperosmolar mannitol securely opens the BBB and enhances intra-arterial cell delivery. A noninjured normal canine model in which the BBB was presumed to be closed was used to evaluate the feasibility and safety of the tested protocol. Autologous adipose tissue-derived pericytes with platelet-derived growth factor receptor β positivity were utilized. Cells were administered 5 min after mannitol pretreatment using one of following techniques: (1) bolus injection of a concentrated suspension, (2) continuous infusion of a diluted suspension, or (3) bolus injection of a concentrated suspension that had been shaken by repeated syringe pumping. Animals administered a concentrated cell suspension without mannitol pretreatment served as a control group. Vital signs, blood parameters, neurologic status, and major artery patency were kept stable throughout the experiment and the 1-month posttreatment period. Although ischemic lesions were noted on magnetic resonance imaging in several mongrel dogs with concentrated cell suspension, the injection technique using repeated syringe shaking could avert this complication. The cells were detected in both ipsilateral and contralateral cortices and were more frequent at the ipsilateral and frontal locations, whereas very few cells were observed anywhere in the brain when mannitol was not preinjected. These data suggest that intra-arterial cell infusion with mannitol pretreatment is a feasible and safe therapeutic approach in stable brain diseases such as chronic stroke.

Blood-brain barrier and its function during inflammation and autoimmunity.

PubMed

Sonar, Sandip Ashok; Lal, Girdhari

2018-05-01

The blood-brain barrier (BBB) is an important physiologic barrier that separates CNS from soluble inflammatory mediators and effector immune cells from peripheral circulation. The optimum function of the BBB is necessary for the homeostasis, maintenance, and proper neuronal function. The clinical and experimental findings have shown that BBB dysfunction is an early hallmark of various neurologic disorders ranging from inflammatory autoimmune, neurodegenerative, and traumatic diseases to neuroinvasive infections. Significant progress has been made in the understanding of the regulation of BBB function under homeostatic and neuroinflammatory conditions. Several neurologic disease-modifying drugs have shown to improve the BBB function. However, they have a broad-acting immunomodulatory function and can increase the risk of life-threatening infections. The recent development of in vitro multicomponent 3-dimensional BBB models coupled with fluidics chamber as well as a cell-type specific reporter and knockout mice gave a new boost to our understanding of the dynamics of the BBB. In the review, we discuss the current understanding of BBB composition and recent findings that illustrate the critical regulatory elements of the BBB function under physiologic and inflammatory conditions, and also suggested the strategies to control BBB structure and function. ©2018 Society for Leukocyte Biology.

Identification of Reversible Disruption of the Human Blood-Brain Barrier Following Acute Ischemia.

PubMed

Simpkins, Alexis N; Dias, Christian; Leigh, Richard

2016-09-01

Animal models of acute cerebral ischemia have demonstrated that diffuse blood-brain barrier (BBB) disruption can be reversible after early reperfusion. However, irreversible, focal BBB disruption in humans is associated with hemorrhagic transformation in patients receiving intravenous thrombolytic therapy. The goal of this study was to use a magnetic resonance imaging biomarker of BBB permeability to differentiate these 2 forms of BBB disruption. Acute stroke patients imaged with magnetic resonance imaging before, 2 hours after, and 24 hours after treatment with intravenous tissue-type plasminogen activator were included. The average BBB permeability of the acute ischemic region before and 2 hours after treatment was calculated using a T2* perfusion-weighted source images. Change in average permeability was compared with percent reperfusion using linear regression. Focal regions of maximal BBB permeability from the pretreatment magnetic resonance imaging were compared with the occurrence of parenchymal hematoma (PH) formation on the 24-hour magnetic resonance imaging scan using logistic regression. Signals indicating reversible BBB permeability were detected in 18/36 patients. Change in average BBB permeability correlated inversely with percent reperfusion (P=0.006), indicating that early reperfusion is associated with decreased BBB permeability, whereas sustained ischemia is associated with increased BBB disruption. Focal regions of maximal BBB permeability were significantly associated with subsequent formation of PH (P=0.013). This study demonstrates that diffuse, mild BBB disruption in the acutely ischemic human brain is reversible with reperfusion. This study also confirms prior findings that focal severe BBB disruption confers an increased risk of hemorrhagic transformation in patients treated with intravenous tissue-type plasminogen activator. © 2016 American Heart Association, Inc.

Tau depletion prevents progressive blood-brain barrier damage in a mouse model of tauopathy.

PubMed

Blair, Laura J; Frauen, Haley D; Zhang, Bo; Nordhues, Bryce A; Bijan, Sara; Lin, Yen-Chi; Zamudio, Frank; Hernandez, Lidice D; Sabbagh, Jonathan J; Selenica, Maj-Linda B; Dickey, Chad A

2015-01-31

The blood-brain barrier (BBB) is damaged in tauopathies, including progressive supranuclear palsy (PSP) and Alzheimer's disease (AD), which is thought to contribute to pathogenesis later in the disease course. In AD, BBB dysfunction has been associated with amyloid beta (Aß) pathology, but the role of tau in this process is not well characterized. Since increased BBB permeability is found in tauopathies without Aß pathology, like PSP, we suspected that tau accumulation alone could not only be sufficient, but even more important than Aß for BBB damage. Longitudinal evaluation of brain tissue from the tetracycline-regulatable rTg4510 tau transgenic mouse model showed progressive IgG, T cell and red blood cell infiltration. The Evans blue (EB) dye that is excluded from the brain when the BBB is intact also permeated the brains of rTg4510 mice following peripheral administration, indicative of a bonafide BBB defect, but this was only evident later in life. Thus, despite the marked brain atrophy and inflammation that occurs earlier in this model, BBB integrity is maintained. Interestingly, BBB dysfunction emerged at the same time that perivascular tau emerged around major hippocampal blood vessels. However, when tau expression was suppressed using doxycycline, BBB integrity was preserved, suggesting that the BBB can be stabilized in a tauopathic brain by reducing tau levels. For the first time, these data demonstrate that tau alone can initiate breakdown of the BBB, but the BBB is remarkably resilient, maintaining its integrity in the face of marked brain atrophy, neuroinflammation and toxic tau accumulation. Moreover, the BBB can recover integrity when tau levels are reduced. Thus, late stage interventions targeting tau may slow the vascular contributions to cognitive impairment and dementia that occur in tauopathies.

Experimental methods and transport models for drug delivery across the blood-brain barrier.

PubMed

Fu, Bingmei M

2012-06-01

The blood-brain barrier (BBB) is a dynamic barrier essential for maintaining the micro-environment of the brain. Although the special anatomical features of the BBB determine its protective role for the central nervous system (CNS) from blood-born neurotoxins, however, the BBB extremely limits the therapeutic efficacy of drugs into the CNS, which greatly hinders the treatment of major brain diseases. This review summarized the unique structures of the BBB, described a variety of in vivo and in vitro experimental methods for determining the transport properties of the BBB, e.g., the permeability of the BBB to water, ions, and solutes including nutrients, therapeutic agents and drug carriers, and presented newly developed mathematical models which quantitatively correlate the anatomical structures of the BBB with its barrier functions. Finally, on the basis of the experimental observations and the quantitative models, several strategies for drug delivery through the BBB were proposed.

Experimental Methods and Transport Models for Drug Delivery across the Blood-Brain Barrier

PubMed Central

Fu, Bingmei M

2017-01-01

The blood-brain barrier (BBB) is a dynamic barrier essential for maintaining the micro-environment of the brain. Although the special anatomical features of the BBB determine its protective role for the central nervous system (CNS) from blood-born neurotoxins, however, the BBB extremely limits the therapeutic efficacy of drugs into the CNS, which greatly hinders the treatment of major brain diseases. This review summarized the unique structures of the BBB, described a variety of in vivo and in vitro experimental methods for determining the transport properties of the BBB, e.g., the permeability of the BBB to water, ions, and solutes including nutrients, therapeutic agents and drug carriers, and presented newly developed mathematical models which quantitatively correlate the anatomical structures of the BBB with its barrier functions. Finally, on the basis of the experimental observations and the quantitative models, several strategies for drug delivery through the BBB were proposed. PMID:22201587

Rapamycin alleviates brain edema after focal cerebral ischemia reperfusion in rats.

PubMed

Guo, Wei; Feng, Guoying; Miao, Yanying; Liu, Guixiang; Xu, Chunsheng

2014-06-01

Brain edema is a major consequence of cerebral ischemia reperfusion. However, few effective therapeutic options are available for retarding the brain edema progression after cerebral ischemia. Recently, rapamycin has been shown to produce neuroprotective effects in rats after cerebral ischemia reperfusion. Whether rapamycin could alleviate this brain edema injury is still unclear. In this study, the rat stroke model was induced by a 1-h left transient middle cerebral artery occlusion using an intraluminal filament, followed by 48 h of reperfusion. The effects of rapamycin (250 μg/kg body weight, intraperitoneal; i.p.) on brain edema progression were evaluated. The results showed that rapamycin treatment significantly reduced the infarct volume, the water content of the brain tissue and the Evans blue extravasation through the blood-brain barrier (BBB). Rapamycin treatment could improve histological appearance of the brain tissue, increased the capillary lumen space and maintain the integrity of BBB. Rapamycin also inhibited matrix metalloproteinase 9 (MMP9) and aquaporin 4 (AQP4) expression. These data imply that rapamycin could improve brain edema progression after reperfusion injury through maintaining BBB integrity and inhibiting MMP9 and AQP4 expression. The data of this study provide a new possible approach for improving brain edema after cerebral ischemia reperfusion by administration of rapamycin.

Ginsenoside Rg1 nanoparticle penetrating the blood-brain barrier to improve the cerebral function of diabetic rats complicated with cerebral infarction.

PubMed

Shen, Junyi; Zhao, Zhiming; Shang, Wei; Liu, Chunli; Zhang, Beibei; Zhao, Lingjie; Cai, Hui

2017-01-01

Diabetic cerebral infarction is with poorer prognosis and high rates of mortality. Ginsenoside Rg1 (Rg1) has a wide variety of therapeutic values for central nervous system (CNS) diseases for the neuron protective effects. However, the blood-brain barrier (BBB) restricts Rg1 in reaching the CNS. In this study, we investigated the therapeutic effects of Rg1 nanoparticle (PHRO, fabricated with γ-PGA, L-PAE (H), Rg1, and OX26 antibody), targeting transferrin receptor, on the diabetes rats complicated with diabetic cerebral infarction in vitro and in vivo. Dynamic light scattering analysis shows the average particle size of PHRO was 79±18 nm and the polydispersity index =0.18. The transmission electron microscope images showed that all NPs were spherical in shape with diameters of 89±23 nm. PHRO released Rg1 with sustained release manner and could promote the migration of cerebrovascular endothelial cells and tube formation and even penetrated the BBB in vitro. PHRO could penetrate the BBB with high concentration in brain tissue to reduce the cerebral infarction volume and promote neuronal recovery in vivo. PHRO was promising to be a clinical treatment of diabetes mellitus with cerebral infarction.

Ginsenoside Rg1 nanoparticle penetrating the blood–brain barrier to improve the cerebral function of diabetic rats complicated with cerebral infarction

PubMed Central

Shen, Junyi; Zhao, Zhiming; Shang, Wei; Liu, Chunli; Zhang, Beibei; Zhao, Lingjie; Cai, Hui

2017-01-01

Diabetic cerebral infarction is with poorer prognosis and high rates of mortality. Ginsenoside Rg1 (Rg1) has a wide variety of therapeutic values for central nervous system (CNS) diseases for the neuron protective effects. However, the blood–brain barrier (BBB) restricts Rg1 in reaching the CNS. In this study, we investigated the therapeutic effects of Rg1 nanoparticle (PHRO, fabricated with γ-PGA, L-PAE (H), Rg1, and OX26 antibody), targeting transferrin receptor, on the diabetes rats complicated with diabetic cerebral infarction in vitro and in vivo. Dynamic light scattering analysis shows the average particle size of PHRO was 79±18 nm and the polydispersity index =0.18. The transmission electron microscope images showed that all NPs were spherical in shape with diameters of 89±23 nm. PHRO released Rg1 with sustained release manner and could promote the migration of cerebrovascular endothelial cells and tube formation and even penetrated the BBB in vitro. PHRO could penetrate the BBB with high concentration in brain tissue to reduce the cerebral infarction volume and promote neuronal recovery in vivo. PHRO was promising to be a clinical treatment of diabetes mellitus with cerebral infarction. PMID:28919749

Early Blood-Brain Barrier Disruption after Mechanical Thrombectomy in Acute Ischemic Stroke.

PubMed

Shi, Zhong-Song; Duckwiler, Gary R; Jahan, Reza; Tateshima, Satoshi; Szeder, Viktor; Saver, Jeffrey L; Kim, Doojin; Sharma, Latisha K; Vespa, Paul M; Salamon, Noriko; Villablanca, J Pablo; Viñuela, Fernando; Feng, Lei; Loh, Yince; Liebeskind, David S

2018-05-01

The impact of blood-brain barrier (BBB) disruption can be detected by intraparenchymal hyperdense lesion on the computed tomography (CT) scan after endovascular stroke therapy. The purpose of this study was to determine whether early BBB disruption predicts intracranial hemorrhage and poor outcome in patients with acute ischemic stroke treated with mechanical thrombectomy. We analyzed patients with anterior circulation stroke treated with mechanical thrombectomy and identified BBB disruption on the noncontrast CT images immediately after endovascular treatment. Follow-up CT or magnetic resonance imaging scan was performed at 24 hours to assess intracranial hemorrhage. We dichotomized patients into those with moderate BBB disruption versus those with minor BBB disruption and no BBB disruption. We evaluated the association of moderate BBB disruption after mechanical thrombectomy with intracranial hemorrhage and clinical outcomes. Moderate BBB disruption after mechanical thrombectomy was found in 56 of 210 patients (26.7%). Moderate BBB disruption was independently associated with higher rates of hemorrhagic transformation (OR 25.33; 95% CI 9.93-64.65; P < .001), parenchymal hematoma (OR 20.57; 95% CI 5.64-74.99; P < .001), and poor outcome at discharge (OR 2.35; 95% CI 1.09-5.07; P = .03). The association of BBB disruption with intracranial hemorrhage remained in patients with successful reperfusion after mechanical thrombectomy. The location of BBB disruption was not associated with intracranial hemorrhage and poor outcome. Moderate BBB disruption is common after mechanical thrombectomy in a quarter of patients with acute ischemic stroke and increases the risk of intracranial hemorrhage and poor outcome. Copyright © 2018 by the American Society of Neuroimaging.

Magnetic resonance-guided motorized transcranial ultrasound system for blood-brain barrier permeabilization along arbitrary trajectories in rodents.

PubMed

Magnin, Rémi; Rabusseau, Fabien; Salabartan, Frédéric; Mériaux, Sébastien; Aubry, Jean-François; Le Bihan, Denis; Dumont, Erik; Larrat, Benoit

2015-01-01

Focused ultrasound combined with microbubble injection is capable of locally and transiently enhancing the permeability of the blood-brain barrier (BBB). Magnetic resonance imaging (MRI) guidance enables to plan, monitor, and characterize the BBB disruption. Being able to precisely and remotely control the permeabilization location is of great interest to perform reproducible drug delivery protocols. In this study, we developed an MR-guided motorized focused ultrasound (FUS) system allowing the transducer displacement within preclinical MRI scanners, coupled with real-time transfer and reconstruction of MRI images, to help ultrasound guidance. Capabilities of this new device to deliver large molecules to the brain on either single locations or along arbitrary trajectories were characterized in vivo on healthy rats and mice using 1.5 MHz ultrasound sonications combined with microbubble injection. The efficacy of BBB permeabilization was assessed by injecting a gadolinium-based MR contrast agent that does not cross the intact BBB. The compact motorized FUS system developed in this work fits into the 9-cm inner diameter of the gradient insert installed on our 7-T preclinical MRI scanners. MR images acquired after contrast agent injection confirmed that this device can be used to enhance BBB permeability along remotely controlled spatial trajectories of the FUS beam in both rats and mice. The two-axis motor stage enables reaching any region of interest in the rodent brain. The positioning error when targeting the same anatomical location on different animals was estimated to be smaller than 0.5 mm. Finally, this device was demonstrated to be useful for testing BBB opening at various acoustic pressures (0.2, 0.4, 0.7, and 0.9 MPa) in the same animal and during one single ultrasound session. Our system offers the unique possibility to move the transducer within a high magnetic field preclinical MRI scanner, thus enabling the delivery of large molecules to virtually any rodent brain area in a non-invasive manner. It results in time-saving and reproducibility and could be used to either deliver drugs over large parts of the brain or test different acoustic conditions on the same animal during the same session, therefore reducing physiological variability.

Drug transport across the blood–brain barrier

PubMed Central

Pardridge, William M

2012-01-01

The blood–brain barrier (BBB) prevents the brain uptake of most pharmaceuticals. This property arises from the epithelial-like tight junctions within the brain capillary endothelium. The BBB is anatomically and functionally distinct from the blood–cerebrospinal fluid barrier at the choroid plexus. Certain small molecule drugs may cross the BBB via lipid-mediated free diffusion, providing the drug has a molecular weight <400 Da and forms <8 hydrogen bonds. These chemical properties are lacking in the majority of small molecule drugs, and all large molecule drugs. Nevertheless, drugs can be reengineered for BBB transport, based on the knowledge of the endogenous transport systems within the BBB. Small molecule drugs can be synthesized that access carrier-mediated transport (CMT) systems within the BBB. Large molecule drugs can be reengineered with molecular Trojan horse delivery systems to access receptor-mediated transport (RMT) systems within the BBB. Peptide and antisense radiopharmaceuticals are made brain-penetrating with the combined use of RMT-based delivery systems and avidin–biotin technology. Knowledge on the endogenous CMT and RMT systems expressed at the BBB enable new solutions to the problem of BBB drug transport. PMID:22929442

Three-Dimensional Blood-Brain Barrier Model for in vitro Studies of Neurovascular Pathology

NASA Astrophysics Data System (ADS)

Cho, Hansang; Seo, Ji Hae; Wong, Keith H. K.; Terasaki, Yasukazu; Park, Joseph; Bong, Kiwan; Arai, Ken; Lo, Eng H.; Irimia, Daniel

2015-10-01

Blood-brain barrier (BBB) pathology leads to neurovascular disorders and is an important target for therapies. However, the study of BBB pathology is difficult in the absence of models that are simple and relevant. In vivo animal models are highly relevant, however they are hampered by complex, multi-cellular interactions that are difficult to decouple. In vitro models of BBB are simpler, however they have limited functionality and relevance to disease processes. To address these limitations, we developed a 3-dimensional (3D) model of BBB on a microfluidic platform. We verified the tightness of the BBB by showing its ability to reduce the leakage of dyes and to block the transmigration of immune cells towards chemoattractants. Moreover, we verified the localization at endothelial cell boundaries of ZO-1 and VE-Cadherin, two components of tight and adherens junctions. To validate the functionality of the BBB model, we probed its disruption by neuro-inflammation mediators and ischemic conditions and measured the protective function of antioxidant and ROCK-inhibitor treatments. Overall, our 3D BBB model provides a robust platform, adequate for detailed functional studies of BBB and for the screening of BBB-targeting drugs in neurological diseases.

Growth inhibition in a brain metastasis model by antibody delivery using focused ultrasound-mediated blood-brain barrier disruption.

PubMed

Kobus, Thiele; Zervantonakis, Ioannis K; Zhang, Yongzhi; McDannold, Nathan J

2016-09-28

HER2-targeting antibodies (i.e. trastuzumab and pertuzumab) prolong survival in HER2-positive breast cancer patients with extracranial metastases. However, the response of brain metastases to these drugs is poor, and it is hypothesized that the blood-brain barrier (BBB) limits drug delivery to the brain. We investigated whether we could improve the response by temporary disruption of the BBB using focused ultrasound in combination with microbubbles. To study this, we inoculated 30 nude rats with HER2-positive cells derived from a brain metastasis of a breast cancer patient (MDA-MB-361). The animals were divided into three groups: a control-group that received no treatment; an antibody-only group that received six weekly treatments of trastuzumab and pertuzumab; and an ultrasound+antibody group that received trastuzumab and pertuzumab in combination with six weekly sessions of BBB disruption using focused ultrasound. In two animals, the leakiness of the tumors before disruption was evaluated using contrast-enhanced T1-weighted magnetic resonance imaging and found that the tumors were not leaky. The same technique was used to evaluate the effectiveness of BBB disruption, which was successful in all sessions. The tumor in the control animals grew exponentially with a growth constant of 0.042±0.011mm(3)/day. None of the antibody-only animals responded to the treatment and the growth constant was 0.033±0.009mm(3)/day during the treatment period. Four of the ten animals in the ultrasound+antibody-group showed a response to the treatment with an average growth constant of 0.010±0.007mm(3)/day, compared to a growth constant 0.043±0.013mm(3)/day for the six non-responders. After the treatment period, the tumors in all groups grew at similar rates. As the tumors were not leaky before BBB disruption and there were no responders in the antibody-only group, these results show that at least in some cases disruption of the BBB is necessary for a response to the antibodies in these brain metastases. Interestingly, only some of the rats responded to the treatment. We did not observe a difference in tumor volume at the start of the treatment, nor in HER2 expression or in contrast-enhancement on MRI between the responders and non-responders to explain this. Better understanding of why certain animals respond is needed and will help in translating this technique to the clinic. In conclusion, we demonstrate that BBB disruption using focused ultrasound in combination with antibody therapy can inhibit growth of breast cancer brain metastasis. Copyright © 2016 Elsevier B.V. All rights reserved.

Green tea polyphenols alleviate early BBB damage during experimental focal cerebral ischemia through regulating tight junctions and PKCalpha signaling.

PubMed

Liu, Xiaobai; Wang, Zhenhua; Wang, Ping; Yu, Bo; Liu, Yunhui; Xue, Yixue

2013-07-21

It has been supposed that green tea polyphenols (GTPs) have neuroprotective effects on brain damage after brain ischemia in animal experiments. Little is known regarding GTPs' protective effects against the blood-brain barrier (BBB) disruption after ischemic stroke. We investigated the effects of GTPs on the expression of claudin-5, occludin, and ZO-1, and the corresponding cellular mechanisms involved in the early stage of cerebral ischemia. Male Wistar rats were subjected to a middle cerebral artery occlusion (MCAO) for 0, 30, 60, and 120 min. GTPs (400 mg/kg/day) or vehicle was administered by intragastric gavage twice a day for 30 days prior to MCAO. At different time points, the expression of claudin-5, occludin, ZO-1, and PKCα signaling pathway in microvessel fragments of cerebral ischemic tissue were evaluated. GTPs reduced BBB permeability at 60 min and 120 min after ischemia as compared with the vehicle group. Transmission electron microscopy also revealed that GTPs could reverse the opening of tight junction (TJ) barrier at 60 min and 120 min after MACO. The decreased mRNA and protein expression levels of claudin-5, occludin, and ZO-1 in microvessel fragments of cerebral ischemic tissue were significantly prevented by treatment with GTPs at the same time points after ischemia in rats. Furthermore, GTPs could attenuate the increase in the expression levels of PKCα mRNA and protein caused by cerebral ischemia. These results demonstrate that GTPs may act as a potential neuroprotective agent against BBB damage at the early stage of focal cerebral ischemia through the regulation of TJ and PKCα signaling.

Noninvasive, localized, and transient brain drug delivery using focused ultrasound and microbubbles

NASA Astrophysics Data System (ADS)

Choi, James J.

In the United States, Alzheimer's disease (AD), Parkinson's disease (PD), and brain cancer caused 72,432, 19,566 and 12,886 deaths in 2006, respectively. Whereas the number of deaths due to major disorders such as heart disease, stroke, and prostate cancer have decreased since 2006, deaths attributed to AD, PD, and brain cancer have not. Treatment options for patients with CNS disorders remain limited despite significant advances in knowledge of CNS disease pathways and development of neurologically potent agents. One of the major obstacles is that the cerebral microvasculature is lined by a specialized and highly regulated blood-brain barrier (BBB) that prevents large agents from entering the brain extracellular space. The purpose of this dissertation is to design a noninvasive, localized, and transient BBB opening system using focused ultrasound (FUS) and determine ultrasound and microbubble conditions that can effectively and safely deliver large pharmacologically-relevant-sized agents to the brain. To meet this end, an in vivo mouse brain drug delivery system using a stereotactic-based targeting method was developed. FUS was applied noninvasively through the intact skin and skull, which allowed for long-term and high-throughput studies. With this system, more than 150 mice were exposed to one of 31 distinct acoustic and microbubble conditions. The feasibility of delivering a large MRI contrast agent was first demonstrated in vivo in both wild-type and transgenic Alzheimer's disease model (APP/PS1) mice. A wide range of acoustic and microbubble conditions were then evaluated for their ability to deliver agents to a target region. Interestingly, the possible design space of parameters was found to be vast and different conditions resulted in distinct spatial distributions and doses delivered. In particular, BBB opening was shown to be dependent on the microbubble diameter, acoustic pressure, pulse repetition frequency (PRF), and pulse length (PL). Each set of conditions determined both the size of agents that can traverse the BBB, and also the level of safety of the technique. In one set of conditions (peak-rarefactional pressure: 0.61 MPa, PRF: 10 Hz, PL: 20 ms), large 70-kDa dextran was delivered to a target region, but were associated with detectable damaged sites as indicated by dark neurons, microvacuolations, and erythrocyte extravasations. Another set of conditions (peak-rarefactional pressure: 0.46 MPa, PRF: 5 Hz, PL: 0.2 ms) delivered 3-kDa dextran homogeneously and diffusely to a target region in the brain without any detectable dark neurons, microvacuolations, or erythrocyte extravasations. Each distinct set of conditions may thus be used for different clinical application, i.e., treatment of brain cancer and AD. In conclusion, an effective method to noninvasively, locally, and transiently deliver large therapeutic agents through the BBB was developed.

Glial Expression of Disease-associated Poly-glutamine Proteins Impairs the Blood-Brain Barrier in Drosophila.

PubMed

Yeh, Po-An; Liu, Ya-Hsin; Chu, Wei-Chen; Liu, Jia-Yu; Sun, Y Henry

2018-05-02

Expansion of poly-glutamine (polyQ) stretches in several proteins has been linked to neurodegenerative diseases. The effects of polyQ-expanded proteins on neurons have been extensively studied, but their effects on glia remain unclear. We found that expression of distinct polyQ proteins exclusively in all glia or specifically in the blood-brain barrier (BBB) and blood-retina barrier (BRB) glia caused cell-autonomous impairment of BBB/BRB integrity, suggesting that BBB/BRB glia are most vulnerable to polyQ-expanded proteins. Furthermore, we also found that BBB/BRB leakage in Drosophila is reflected in reversed waveform polarity based on electroretinography (ERG), making ERG a sensitive method to detect BBB/BRB leakage. The polyQ-expanded protein Atxn3-84Q forms aggregates, induces BBB/BRB leakage, restricts Drosophila lifespan, and reduces the level of Repo (a pan-glial transcriptional factor required for glial differentiation). Expression of Repo in BBB/BRB glia can rescue BBB/BRB leakage, suggesting that the reduced expression of Repo is important for the effect of polyQ on BBB/BRB impairment. Coexpression of the chaperon HSP40 and HSP70 effectively rescues the effects of Atxn3-84Q, indicating that polyQ protein aggregation in glia is deleterious. Intriguingly, coexpression of wildtype Atxn3-27Q can also rescue BBB/BRB impairment, suggesting that normal polyQ protein may have a protective function.

Strategies for transporting nanoparticles across the blood-brain barrier.

PubMed

Zhang, Tian-Tian; Li, Wen; Meng, Guanmin; Wang, Pei; Liao, Wenzhen

2016-02-01

The existence of blood-brain barrier (BBB) hampers the effective treatment of central nervous system (CNS) diseases. Almost all macromolecular drugs and more than 98% of small molecule drugs cannot pass the BBB. Therefore, the BBB remains a big challenge for delivery of therapeutics to the central nervous system. With the structural and mechanistic elucidation of the BBB under both physiological and pathological conditions, it is now possible to design delivery systems that could cross the BBB effectively. Because of their advantageous properties, nanoparticles have been widely deployed for brain-targeted delivery. This review paper presents the current understanding of the BBB under physiological and pathological conditions, and summarizes strategies and systems for BBB crossing with a focus on nanoparticle-based drug delivery systems. In summary, with wider applications and broader prospection the treatment of brain targeted therapy, nano-medicines have proved to be more potent, more specific and less toxic than traditional drug therapy.

Gpr124 is essential for blood-brain barrier integrity in central nervous system disease.

PubMed

Chang, Junlei; Mancuso, Michael R; Maier, Carolina; Liang, Xibin; Yuki, Kanako; Yang, Lu; Kwong, Jeffrey W; Wang, Jing; Rao, Varsha; Vallon, Mario; Kosinski, Cynthia; Zhang, J J Haijing; Mah, Amanda T; Xu, Lijun; Li, Le; Gholamin, Sharareh; Reyes, Teresa F; Li, Rui; Kuhnert, Frank; Han, Xiaoyuan; Yuan, Jenny; Chiou, Shin-Heng; Brettman, Ari D; Daly, Lauren; Corney, David C; Cheshier, Samuel H; Shortliffe, Linda D; Wu, Xiwei; Snyder, Michael; Chan, Pak; Giffard, Rona G; Chang, Howard Y; Andreasson, Katrin; Kuo, Calvin J

2017-04-01

Although blood-brain barrier (BBB) compromise is central to the etiology of diverse central nervous system (CNS) disorders, endothelial receptor proteins that control BBB function are poorly defined. The endothelial G-protein-coupled receptor (GPCR) Gpr124 has been reported to be required for normal forebrain angiogenesis and BBB function in mouse embryos, but the role of this receptor in adult animals is unknown. Here Gpr124 conditional knockout (CKO) in the endothelia of adult mice did not affect homeostatic BBB integrity, but resulted in BBB disruption and microvascular hemorrhage in mouse models of both ischemic stroke and glioblastoma, accompanied by reduced cerebrovascular canonical Wnt-β-catenin signaling. Constitutive activation of Wnt-β-catenin signaling fully corrected the BBB disruption and hemorrhage defects of Gpr124-CKO mice, with rescue of the endothelial gene tight junction, pericyte coverage and extracellular-matrix deficits. We thus identify Gpr124 as an endothelial GPCR specifically required for endothelial Wnt signaling and BBB integrity under pathological conditions in adult mice. This finding implicates Gpr124 as a potential therapeutic target for human CNS disorders characterized by BBB disruption.

Drug Delivery to the Brain in Alzheimer’s Disease: Consideration of the Blood-brain Barrier

PubMed Central

Banks, William A.

2012-01-01

The successful treatment of Alzheimer’s disease (AD) will require drugs that can negotiate the blood-brain barrier (BBB). However, the BBB is not simply a physical barrier, but a complex interface that is in intimate communication with the rest of the central nervous system (CNS) and influenced by peripheral tissues. This review examines three aspects of the BBB in AD. First, it considers how the BBB may be contributing to the onset and progression of AD. In this regard, the BBB itself is a therapeutic target in the treatment of AD. Second, it examines how the BBB restricts drugs that might otherwise be useful in the treatment of AD and examines strategies being developed to deliver drugs to the CNS for the treatment of AD. Third, it considers how drug penetration across the AD BBB may differ from the BBB of normal aging. In this case, those differences can complicate the treatment of CNS diseases such as depression, delirium, psychoses, and pain control in the AD population. PMID:22202501

Claudin-1 induced sealing of blood-brain barrier tight junctions ameliorates chronic experimental autoimmune encephalomyelitis.

PubMed

Pfeiffer, Friederike; Schäfer, Julia; Lyck, Ruth; Makrides, Victoria; Brunner, Sarah; Schaeren-Wiemers, Nicole; Deutsch, Urban; Engelhardt, Britta

2011-11-01

In experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis (MS), loss of the blood-brain barrier (BBB) tight junction (TJ) protein claudin-3 correlates with immune cell infiltration into the CNS and BBB leakiness. Here we show that sealing BBB TJs by ectopic tetracycline-regulated expression of the TJ protein claudin-1 in Tie-2 tTA//TRE-claudin-1 double transgenic C57BL/6 mice had no influence on immune cell trafficking across the BBB during EAE and furthermore did not influence the onset and severity of the first clinical disease episode. However, expression of claudin-1 did significantly reduce BBB leakiness for both blood borne tracers and endogenous plasma proteins specifically around vessels expressing claudin-1. In addition, mice expressing claudin-1 exhibited a reduced disease burden during the chronic phase of EAE as compared to control littermates. Our study identifies BBB TJs as the critical structure regulating BBB permeability but not immune cell trafficking into CNS during EAE, and indicates BBB dysfunction is a potential key event contributing to disease burden in the chronic phase of EAE. Our observations suggest that stabilizing BBB barrier function by therapeutic targeting of TJs may be beneficial in treating MS, especially when anti-inflammatory treatments have failed.

Cytokine Signaling Modulates Blood-Brain Barrier Function

PubMed Central

Pan, Weihong; Stone, Kirsten P.; Hsuchou, Hung; Manda, Vamshi K.; Zhang, Yan; Kastin, Abba J.

2014-01-01

The blood-brain barrier (BBB) provides a vast interface for cytokines to affect CNS function. The BBB is a target for therapeutic intervention. It is essential, therefore, to understand how cytokines interact with each other at the level of the BBB and how secondary signals modulate CNS functions beyond the BBB. The interactions between cytokines and lipids, however, have not been fully addressed at the level of the BBB. Here, we summarize current understanding of the localization of cytokine receptors and transporters in specific membrane microdomains, particularly lipid rafts, on the luminal (apical) surface of the microvascular endothelial cells composing the BBB. We then illustrate the clinical context of cytokine effects on the BBB by neuroendocrine regulation and amplification of inflammatory signals. Two unusual aspects discussed are signaling crosstalk by different classes of cytokines and genetic regulation of drug efflux transporters. We also introduce a novel area of focus on how cytokines may act through nuclear hormone receptors to modulate efflux transporters and other targets. A specific example discussed is the ATP-binding cassette transporter-1 (ABCA-1) that regulates lipid metabolism. Overall, cytokine signaling at the level of the BBB is a crucial feature of the dynamic regulation that can rapidly change BBB function and affect brain health and disease. PMID:21834767

Region-specific disruption of the blood-brain barrier following repeated inflammatory dural stimulation in a rat model of chronic trigeminal allodynia

PubMed Central

Fried, Nathan T; Maxwell, Christina R; Elliott, Melanie B; Oshinsky, Michael L

2017-01-01

Background The blood-brain barrier (BBB) has been hypothesized to play a role in migraine since the late 1970s. Despite this, limited investigation of the BBB in migraine has been conducted. We used the inflammatory soup rat model of trigeminal allodynia, which closely mimics chronic migraine, to determine the impact of repeated dural inflammatory stimulation on BBB permeability. Methods The sodium fluorescein BBB permeability assay was used in multiple brain regions (trigeminal nucleus caudalis (TNC), periaqueductal grey, frontal cortex, sub-cortex, and cortex directly below the area of dural activation) during the episodic and chronic stages of repeated inflammatory dural stimulation. Glial activation was assessed in the TNC via GFAP and OX42 immunoreactivity. Minocycline was tested for its ability to prevent BBB disruption and trigeminal sensitivity. Results No astrocyte or microglial activation was found during the episodic stage, but BBB permeability and trigeminal sensitivity were increased. Astrocyte and microglial activation, BBB permeability, and trigeminal sensitivity were increased during the chronic stage. These changes were only found in the TNC. Minocycline treatment prevented BBB permeability modulation and trigeminal sensitivity during the episodic and chronic stages. Discussion Modulation of BBB permeability occurs centrally within the TNC following repeated dural inflammatory stimulation and may play a role in migraine. PMID:28457145

Blood–brain barrier dysfunction and epilepsy: Pathophysiologic role and therapeutic approaches

PubMed Central

Marchi, Nicola; Granata, Tiziana; Ghosh, Chaitali; Janigro, Damir

2016-01-01

The blood–brain barrier (BBB) is located within a unique anatomic interface and has functional ramifications to most of the brain and blood cells. In the past, the BBB was considered a pharmacokinetic impediment to antiepileptic drug penetration into the brain; nowadays it is becoming increasingly evident that targeting of the damaged or dysfunctional BBB may represent a therapeutic approach to reduce seizure burden. Several studies have investigated the mechanisms linking the onset and sustainment of seizures to BBB dysfunction. These studies have shown that the BBB is at the crossroad of a multifactorial pathophysiologic process that involves changes in brain milieu, altered neuroglial physiology, development of brain inflammation, leukocyte–endothelial interactions, faulty angiogenesis, and hemodynamic changes leading to energy mismatch. A number of knowledge gaps, conflicting points of view, and discordance between clinical and experimental data currently characterize this field of neuroscience. As more pieces are added to this puzzle, it is apparent that each mechanism needs to be validated in an appropriate clinical context. We now offer a BBB-centric view of seizure disorders, linking several aspects of seizures and epilepsy physiopathology to BBB dysfunction. We have reviewed the therapeutic, antiseizure effect of drugs that promote BBB repair. We also present BBB neuroimaging as a tool to correlate BBB restoration to seizure mitigation. Add-on cerebrovascular drug could be of efficacy in reducing seizure burden when used in association with neuronal antiepileptic drugs. PMID:22905812

In vitro models and systems for evaluating the dynamics of drug delivery to the healthy and diseased brain.

PubMed

Modarres, Hassan Pezeshgi; Janmaleki, Mohsen; Novin, Mana; Saliba, John; El-Hajj, Fatima; RezayatiCharan, Mahdi; Seyfoori, Amir; Sadabadi, Hamid; Vandal, Milène; Nguyen, Minh Dang; Hasan, Anwarul; Sanati-Nezhad, Amir

2018-03-10

The blood-brain barrier (BBB) plays a crucial role in maintaining brain homeostasis and transport of drugs to the brain. The conventional animal and Transwell BBB models along with emerging microfluidic-based BBB-on-chip systems have provided fundamental functionalities of the BBB and facilitated the testing of drug delivery to the brain tissue. However, developing biomimetic and predictive BBB models capable of reasonably mimicking essential characteristics of the BBB functions is still a challenge. In addition, detailed analysis of the dynamics of drug delivery to the healthy or diseased brain requires not only biomimetic BBB tissue models but also new systems capable of monitoring the BBB microenvironment and dynamics of barrier function and delivery mechanisms. This review provides a comprehensive overview of recent advances in microengineering of BBB models with different functional complexity and mimicking capability of healthy and diseased states. It also discusses new technologies that can make the next generation of biomimetic human BBBs containing integrated biosensors for real-time monitoring the tissue microenvironment and barrier function and correlating it with the dynamics of drug delivery. Such integrated system addresses important brain drug delivery questions related to the treatment of brain diseases. We further discuss how the combination of in vitro BBB systems, computational models and nanotechnology supports for characterization of the dynamics of drug delivery to the brain. Copyright © 2018 Elsevier B.V. All rights reserved.

Permeability of PEGylated immunoarsonoliposomes through in vitro blood brain barrier-medulloblastoma co-culture models for brain tumor therapy.

PubMed

Al-Shehri, Abdulghani; Favretto, Marco E; Ioannou, Panayiotis V; Romero, Ignacio A; Couraud, Pierre-Olivier; Weksler, Babette Barbash; Parker, Terry L; Kallinteri, Paraskevi

2015-03-01

Owing to restricted access of pharmacological agents into the brain due to blood brain barrier (BBB) there is a need: 1. to develop a more representative 3-D-co-culture model of tumor-BBB interaction to investigate drug and nanoparticle transport into the brain for diagnostic and therapeutic evaluation. 2. to address the lack of new alternative methods to animal testing according to replacement-reduction-refinement principles. In this work, in vitro BBB-medulloblastoma 3-D-co-culture models were established using immortalized human primary brain endothelial cells (hCMEC/D3). hCMEC/D3 cells were cultured in presence and in absence of two human medulloblastoma cell lines on Transwell membranes. In vitro models were characterized for BBB formation, zonula occludens-1 expression and permeability to dextran. Transferrin receptors (Tfr) expressed on hCMEC/D3 were exploited to facilitate arsonoliposome (ARL) permeability through the BBB to the tumor by covalently attaching an antibody specific to human Tfr. The effect of anticancer ARLs on hCMEC/D3 was assessed. In vitro BBB and BBB-tumor co-culture models were established successfully. BBB permeability was affected by the presence of tumor aggregates as suggested by increased permeability of ARLs. There was a 6-fold and 8-fold increase in anti-Tfr-ARL uptake into VC312R and BBB-DAOY co-culture models, respectively, compared to plain ARLs. The three-dimensional models might be appropriate models to study the transport of various drugs and nanocarriers (liposomes and immunoarsonoliposomes) through the healthy and diseased BBB. The immunoarsonoliposomes can be potentially used as anticancer agents due to good tolerance of the in vitro BBB model to their toxic effect.

MRI measurements of Blood-Brain Barrier function in dementia: A review of recent studies.

PubMed

Raja, Rajikha; Rosenberg, Gary A; Caprihan, Arvind

2018-05-15

Blood-brain barrier (BBB) separates the systemic circulation and the brain, regulating transport of most molecules to protect the brain microenvironment. Multiple structural and functional components preserve the integrity of the BBB. Several imaging modalities are available to study disruption of the BBB. However, the subtle changes in BBB leakage that occurs in vascular cognitive impairment and Alzheimer's disease have been less well studied. Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is the most widely adopted non-invasive imaging technique for evaluating BBB breakdown. It is used as a significant marker for a wide variety of diseases with large permeability leaks, such as brain tumors and multiple sclerosis, to more subtle disruption in chronic vascular disease and dementia. DCE-MRI analysis of BBB includes both model-free parameters and quantitative parameters using pharmacokinetic modelling. We review MRI studies of BBB breakdown in dementia. The challenges in measuring subtle BBB changes and the state of the art techniques are initially examined. Subsequently, a systematic review comparing methodologies from recent in-vivo MRI studies is presented. Various factors related to subtle BBB permeability measurement such as DCE-MRI acquisition parameters, arterial input assessment, T 1 mapping and data analysis methods are reviewed with the focus on finding the optimal technique. Finally, the reported BBB permeability values in dementia are compared across different studies and across various brain regions. We conclude that reliable measurement of low-level BBB permeability across sites remains a difficult problem and a standardization of the methodology for both data acquisition and quantitative analysis is required. This article is part of the Special Issue entitled 'Cerebral Ischemia'. Copyright © 2017 Elsevier Ltd. All rights reserved.

The extracellular matrix protein laminin-10 promotes blood-brain barrier repair after hypoxia and inflammation in vitro.

PubMed

Kangwantas, Korakoch; Pinteaux, Emmanuel; Penny, Jeffrey

2016-02-01

The blood-brain barrier (BBB) of the central nervous system (CNS) is essential for normal brain function. However, the loss of BBB integrity that occurs after ischaemic injury is associated with extracellular matrix (ECM) remodelling and inflammation, and contributes to poor outcome. ECM remodelling also contributes to BBB repair after injury, but the precise mechanisms and contribution of specific ECM molecules involved are unknown. Here, we investigated the mechanisms by which hypoxia and inflammation trigger loss of BBB integrity and tested the hypothesis ECM changes could contribute to BBB repair in vitro. We used an in vitro model of the BBB, composed of primary rat brain endothelial cells grown on collagen (Col) I-, Col IV-, fibronectin (FN)-, laminin (LM) 8-, or LM10-coated tissue culture plates, either as a single monolayer culture or on Transwell® inserts above mixed glial cell cultures. Cultures were exposed to oxygen-glucose deprivation (OGD) and/or reoxygenation, in the absence or the presence of recombinant interleukin-1β (IL-1β). Cell adhesion to ECM molecules was assessed by cell attachment and cell spreading assays. BBB dysfunction was assessed by immunocytochemistry for tight junction proteins occludin and zona occludens-1 (ZO-1) and measurement of trans-endothelial electrical resistance (TEER). Change in endothelial expression of ECM molecules was assessed by semi-quantitative RT-PCR. OGD and/or IL-1 induce dramatic changes associated with loss of BBB integrity, including cytoplasmic relocalisation of membrane-associated tight junction proteins occludin and ZO-1, cell swelling, and decreased TEER. OGD and IL-1 also induced gene expression of key ECM molecules associated with the BBB, including FN, Col IV, LM 8, and LM10. Importantly, we found that LM10, but not FN, Col IV, nor LM8, plays a key role in maintenance of BBB integrity and reversed most of the key hallmarks of BBB dysfunction induced by IL-1. Our data unravel new mechanisms of BBB dysfunction induced by hypoxia and inflammation and identify LM10 as a key ECM molecule involved in BBB repair after hypoxic injury and inflammation.

Peroxisome proliferator-activated receptors and Alzheimer's disease: hitting the blood-brain barrier.

PubMed

Zolezzi, Juan M; Inestrosa, Nibaldo C

2013-12-01

The blood-brain barrier (BBB) is often affected in several neurodegenerative disorders, such as Alzheimer's disease (AD). Integrity and proper functionality of the neurovascular unit are recognized to be critical for maintenance of the BBB. Research has traditionally focused on structural integrity more than functionality, and BBB alteration has usually been explained more as a consequence than a cause. However, ongoing evidence suggests that at the early stages, the BBB of a diseased brain often shows distinct expression patterns of specific carriers such as members of the ATP-binding cassette (ABC) transport protein family, which alter BBB traffic. In AD, amyloid-β (Aβ) deposits are a pathological hallmark and, as recently highlighted by Cramer et al. (2012), Aβ clearance is quite fundamental and is a less studied approach. Current knowledge suggests that BBB traffic plays a more important role than previously believed and that pharmacological modulation of the BBB may offer new therapeutic alternatives for AD. Recent investigations carried out in our laboratory indicate that peroxisome proliferator-activated receptor (PPAR) agonists are able to prevent Aβ-induced neurotoxicity in hippocampal neurons and cognitive impairment in a double transgenic mouse model of AD. However, even when enough literature about PPAR agonists and neurodegenerative disorders is available, the problem of how they exert their functions and help to prevent and rescue Aβ-induced neurotoxicity is poorly understood. In this review, along with highlighting the main features of the BBB and its role in AD, we will discuss information regarding the modulation of BBB components, including the possible role of PPAR agonists as BBB traffic modulators.

Morphofunctional aspects of the blood-brain barrier.

PubMed

Nico, Beatrice; Ribatti, Domenico

2012-01-01

The blood-brain barrier (BBB) selectively controls the homeostasis of the Central Nervous System (CNS) environment by the specific structural and biochemical features of the endothelial cells, pericytes and glial endfeet, which represent the cellular components of the mature BBB. Endothelial tight junctions (TJs) are the most important structural component of the BBB, and molecular alteration in the phosphorylation state of some TJs proteins, like ZO-1 or occludin, are crucial in determining alterations in the control of BBB vascular permeability. Astrocytes endfeet enveloping the vessels wall, are considered important in the induction and maintenance of the BBB, through secretion of soluble factors, which modulate the expression of enzymatic complexes and antigens by endothelial cells and TJs - associated proteins. Moreover, astrocytes control water flux at BBB site by expressing a specific water channel, namely aquaporin-4 (AQP4), involved in the molecular composition of the orthogonal particles arrays (OAPs) on the perivascular glial endfeet and tightly coupled with the maintenance of the BBB integrity. Disruption of the BBB is a consistent event occurring in the development of several CNS diseases, including demyelinating lesions in the course of relapsing multiple sclerosis, stroke, Duchenne muscular dystrophy (DMD), but also mechanical injures, neurological insults, septic encephalopathy, brain tumors, permanent ischemia or transient ischemia followed by reperfusion. In most cases, these pathological conditions are associated with an increase in microvascular permeability, vasogenic edema, swollen atrocyte endfeet, and BBB disruption.

Hypoxic Stress and Inflammatory Pain Disrupt Blood-Brain Barrier Tight Junctions: Implications for Drug Delivery to the Central Nervous System.

PubMed

Lochhead, Jeffrey J; Ronaldson, Patrick T; Davis, Thomas P

2017-07-01

A functional blood-brain barrier (BBB) is necessary to maintain central nervous system (CNS) homeostasis. Many diseases affecting the CNS, however, alter the functional integrity of the BBB. It has been shown that various diseases and physiological stressors can impact the BBB's ability to selectively restrict passage of substances from the blood to the brain. Modifications of the BBB's permeability properties can potentially contribute to the pathophysiology of CNS diseases and result in altered brain delivery of therapeutic agents. Hypoxia and/or inflammation are central components of a number of diseases affecting the CNS. A number of studies indicate hypoxia or inflammatory pain increase BBB paracellular permeability, induce changes in the expression and/or localization of tight junction proteins, and affect CNS drug uptake. In this review, we look at what is currently known with regard to BBB disruption following a hypoxic or inflammatory insult in vivo. Potential mechanisms involved in altering tight junction components at the BBB are also discussed. A more detailed understanding of the mediators involved in changing BBB functional integrity in response to hypoxia or inflammatory pain could potentially lead to new treatments for CNS diseases with hypoxic or inflammatory components. Additionally, greater insight into the mechanisms involved in TJ rearrangement at the BBB may lead to novel strategies to pharmacologically increase delivery of drugs to the CNS.

Connexin channels provide a target to manipulate brain endothelial calcium dynamics and blood–brain barrier permeability

PubMed Central

De Bock, Marijke; Culot, Maxime; Wang, Nan; Bol, Mélissa; Decrock, Elke; De Vuyst, Elke; da Costa, Anaelle; Dauwe, Ine; Vinken, Mathieu; Simon, Alexander M; Rogiers, Vera; De Ley, Gaspard; Evans, William Howard; Bultynck, Geert; Dupont, Geneviève; Cecchelli, Romeo; Leybaert, Luc

2011-01-01

The cytoplasmic Ca2+ concentration ([Ca2+]i) is an important factor determining the functional state of blood–brain barrier (BBB) endothelial cells but little is known on the effect of dynamic [Ca2+]i changes on BBB function. We applied different agonists that trigger [Ca2+]i oscillations and determined the involvement of connexin channels and subsequent effects on endothelial permeability in immortalized and primary brain endothelial cells. The inflammatory peptide bradykinin (BK) triggered [Ca2+]i oscillations and increased endothelial permeability. The latter was prevented by buffering [Ca2+]i with BAPTA, indicating that [Ca2+]i oscillations are crucial in the permeability changes. Bradykinin-triggered [Ca2+]i oscillations were inhibited by interfering with connexin channels, making use of carbenoxolone, Gap27, a peptide blocker of connexin channels, and Cx37/43 knockdown. Gap27 inhibition of the oscillations was rapid (within minutes) and work with connexin hemichannel-permeable dyes indicated hemichannel opening and purinergic signaling in response to stimulation with BK. Moreover, Gap27 inhibited the BK-triggered endothelial permeability increase in in vitro and in vivo experiments. By contrast, [Ca2+]i oscillations provoked by exposure to adenosine 5′ triphosphate (ATP) were not affected by carbenoxolone or Gap27 and ATP did not disturb endothelial permeability. We conclude that interfering with endothelial connexin hemichannels is a novel approach to limiting BBB-permeability alterations. PMID:21654699

Blood-brain-barrier spheroids as an in vitro screening platform for brain-penetrating agents.

PubMed

Cho, Choi-Fong; Wolfe, Justin M; Fadzen, Colin M; Calligaris, David; Hornburg, Kalvis; Chiocca, E Antonio; Agar, Nathalie Y R; Pentelute, Bradley L; Lawler, Sean E

2017-06-06

Culture-based blood-brain barrier (BBB) models are crucial tools to enable rapid screening of brain-penetrating drugs. However, reproducibility of in vitro barrier properties and permeability remain as major challenges. Here, we report that self-assembling multicellular BBB spheroids display reproducible BBB features and functions. The spheroid core is comprised mainly of astrocytes, while brain endothelial cells and pericytes encase the surface, acting as a barrier that regulates transport of molecules. The spheroid surface exhibits high expression of tight junction proteins, VEGF-dependent permeability, efflux pump activity and receptor-mediated transcytosis of angiopep-2. In contrast, the transwell co-culture system displays comparatively low levels of BBB regulatory proteins, and is unable to discriminate between the transport of angiopep-2 and a control peptide. Finally, we have utilized the BBB spheroids to screen and identify BBB-penetrant cell-penetrating peptides (CPPs). This robust in vitro BBB model could serve as a valuable next-generation platform for expediting the development of CNS therapeutics.

Neuronal and BBB damage induced by sera from patients with secondary progressive multiple sclerosis.

PubMed

Proia, Patrizia; Schiera, Gabriella; Salemi, Giuseppe; Ragonese, Paolo; Savettieri, Giovanni; Di Liegro, Italia

2009-12-01

An important component of the pathogenic process of multiple sclerosis (MS) is the blood-brain barrier (BBB) damage. We recently set an in vitro model of BBB, based on a three-cell-type co-culture system, in which rat neurons and astrocytes synergistically induce brain capillary endothelial cells to form a monolayer with permeability properties resembling those of the physiological BBB. Herein we report that the serum from patients with secondary progressive multiple sclerosis (SPMS) has a damaging effect on isolated neurons. This finding suggests that neuronal damaging in MS could be a primary event and not only secondary to myelin damage, as generally assumed. SPMS serum affects the permeability of the BBB model, as indicated by the decrease of the transendothelial electrical resistance (TEER). Moreover, as shown by both immunofluorescence and Western blot analyses, BBB breaking is accompanied by a decrease of the synthesis as well as the peripheral localization of occludin, a structural protein of the tight junctions that are responsible for BBB properties.

Towards Improvements for Penetrating the Blood–Brain Barrier—Recent Progress from a Material and Pharmaceutical Perspective

PubMed Central

He, Quanguo; Liu, Jun; Liang, Jing; Liu, Xiaopeng; Li, Wen; Liu, Zhi; Ding, Ziyu; Tuo, Du

2018-01-01

The blood–brain barrier (BBB) is a critical biological structure that prevents damage to the brain and maintains its bathing microenvironment. However, this barrier is also the obstacle to deliver beneficial drugs to treat CNS (central nervous system) diseases. Many efforts have been made for improvement of delivering drugs across the BBB in recent years to treat CNS diseases. In this review, the anatomical and functional structure of the BBB is comprehensively discussed. The mechanisms of BBB penetration are summarized, and the methods and effects on increasing BBB permeability are investigated in detail. It also elaborates on the physical, chemical, biological and nanocarrier aspects to improve drug delivery penetration to the brain and introduces some specific drug delivery effects on BBB permeability. PMID:29570659

Evaluation of blood-brain barrier-stealth nanocomposites for in situ glioblastoma theranostics applications

NASA Astrophysics Data System (ADS)

Su, Chia-Hao; Tsai, Ching-Yi; Tomanek, Boguslaw; Chen, Wei-Yu; Cheng, Fong-Yu

2016-04-01

The blood-brain barrier (BBB) is a physiological structure of the blood vessels in the brain. The BBB efficiently traps most therapeutic drugs in the blood vessels and stops them from entering the brain tissue, resulting in a decreased therapeutic efficiency. In this study, we developed BBB-stealth nanocomposites composed of iron oxide (Fe3O4) nanoparticles (NPs) as a safe nanocarrier for glioblastoma therapy. We showed the antitumor activity of Dox/alg-Fe3O4 NPs using in vitro and in vivo tests. We demonstrated that G23-alg-Fe3O4 NPs crossed the BBB and entered the brain. In situ glioblastoma tumor-bearing mice were used to successfully evaluate the antitumor activity of G23-Dox/alg-Fe3O4 NPs. Magnetic resonance imaging (MRI) and bioluminescence imaging (BLI) confirmed the BBB crossing. The BBB-stealth nanocomposites show great potential for a proof-of-concept clinical trial as a theranostics platform for human brain tumor therapy.The blood-brain barrier (BBB) is a physiological structure of the blood vessels in the brain. The BBB efficiently traps most therapeutic drugs in the blood vessels and stops them from entering the brain tissue, resulting in a decreased therapeutic efficiency. In this study, we developed BBB-stealth nanocomposites composed of iron oxide (Fe3O4) nanoparticles (NPs) as a safe nanocarrier for glioblastoma therapy. We showed the antitumor activity of Dox/alg-Fe3O4 NPs using in vitro and in vivo tests. We demonstrated that G23-alg-Fe3O4 NPs crossed the BBB and entered the brain. In situ glioblastoma tumor-bearing mice were used to successfully evaluate the antitumor activity of G23-Dox/alg-Fe3O4 NPs. Magnetic resonance imaging (MRI) and bioluminescence imaging (BLI) confirmed the BBB crossing. The BBB-stealth nanocomposites show great potential for a proof-of-concept clinical trial as a theranostics platform for human brain tumor therapy. Electronic supplementary information (ESI) available: Experimental details. See DOI: 10.1039/c6nr00280c

Peripheral ammonia and blood brain barrier structure and function after methamphetamine.

PubMed

Northrop, Nicole A; Halpin, Laura E; Yamamoto, Bryan K

2016-08-01

An effect of the widely abuse psychostimulant, methamphetamine (Meth), is blood-brain-barrier (BBB) disruption; however, the mechanism by which Meth causes BBB disruption remains unclear. Recently it has been shown that Meth produces liver damage and consequent increases in plasma ammonia. Ammonia can mediate oxidative stress and inflammation, both of which are known to cause BBB disruption. Therefore, the current studies examined the role of peripheral ammonia in Meth-induced disruption of BBB structure and function. A neurotoxic Meth regimen (10 mg/kg, ip, q 2 h, ×4) administered to rats increased plasma ammonia and active MMP-9 in the cortex 2 h after the last Meth injection, compared to saline treated rats. At 24 h after Meth treatment, decreased immunoreactivity of BBB structural proteins, occludin and claudin-5, and increased extravasation of 10,000 Da FITC-dextran were observed, as compared to saline controls. Pretreatment with lactulose (5.3 g/kg, po, q 12 h), a drug that remains in the lumen of the intestine and promotes ammonia excretion, prevented the Meth-induced increases in plasma ammonia. These results were paralleled by the prevention of decreases in BBB structural proteins, increases in extravasation of 10,000 Da FITC-dextran and increases in active MMP-9. The results indicate that Meth-induced increases in ammonia produce BBB disruption and suggest that MMP-9 activation mediates the BBB disruption. These findings identify a novel mechanism of Meth-induced BBB disruption that is mediated by plasma ammonia and are the first to identify a peripheral contribution to Meth-induced BBB disruption. Copyright © 2016 Elsevier Ltd. All rights reserved.

Regional differences in the blood-brain-barrier of the subfornical organs of rats and ducks (Anas platyrhynchos).

PubMed

Schmid, H A

1995-01-01

Recently published electrophysiological data investigated the effect of blood borne and brain intrinsic substances on the activity of neurons in the duck subfornical organ (SFO). This study defines histologically the region in the duck SFO, where blood borne substances can possibly influence neuronal activity. Intravenous injection of Evans blue, a dye which labels brain structures devoid of a blood brain barrier (BBB), resulted in diffuse labelling of the duck SFO from the anterior commissure to the end of the organ in rostrocaudal extension. In addition, specifically labelled neurons could be observed just rostral to the diffuse Evans blue labelling and in an area dorsomedial to the large central blood vessel. The majority of the somata of these heavily stained neurons were located inside the BBB, whereas in the areas with diffuse Evans blue labelling, thus being outside the BBB, labelled cells were rarely observed. Intravenous injection of Evans blue in rats resulted similarly in diffuse labelling of the parenchyma of the medial and caudal part of the SFO, with only a few, but heavily stained cells with fusiform somata. The rostral region of the rat SFO, which is known to have a functional BBB, shows hardly any diffuse labelling, but there the majority of neurons show strong Evans blue fluorescence. It is concluded that the heavily labelled somata inside the BBB have axonal or dendritic projections to BBB-free areas, where they can take up the dye. This study gives a functional description of the extension of the SFO areas without a BBB of rats and ducks. It is concluded that blood borne agents can affect those SFO neurons which have their somata located outside the BBB as well as those located inside the BBB which have terminals projecting to BBB free regions.

In vitro blood-brain barrier permeability predictions for GABAA receptor modulating piperine analogs.

PubMed

Eigenmann, Daniela Elisabeth; Dürig, Carmen; Jähne, Evelyn Andrea; Smieško, Martin; Culot, Maxime; Gosselet, Fabien; Cecchelli, Romeo; Helms, Hans Christian Cederberg; Brodin, Birger; Wimmer, Laurin; Mihovilovic, Marko D; Hamburger, Matthias; Oufir, Mouhssin

2016-06-01

The alkaloid piperine from black pepper (Piper nigrum L.) and several synthetic piperine analogs were recently identified as positive allosteric modulators of γ-aminobutyric acid type A (GABAA) receptors. In order to reach their target sites of action, these compounds need to enter the brain by crossing the blood-brain barrier (BBB). We here evaluated piperine and five selected analogs (SCT-66, SCT-64, SCT-29, LAU397, and LAU399) regarding their BBB permeability. Data were obtained in three in vitro BBB models, namely a recently established human model with immortalized hBMEC cells, a human brain-like endothelial cells (BLEC) model, and a primary animal (bovine endothelial/rat astrocytes co-culture) model. For each compound, quantitative UHPLC-MS/MS methods in the range of 5.00-500ng/mL in the corresponding matrix were developed, and permeability coefficients in the three BBB models were determined. In vitro predictions from the two human BBB models were in good agreement, while permeability data from the animal model differed to some extent, possibly due to protein binding of the screened compounds. In all three BBB models, piperine and SCT-64 displayed the highest BBB permeation potential. This was corroborated by data from in silico prediction. For the other piperine analogs (SCT-66, SCT-29, LAU397, and LAU399), BBB permeability was low to moderate in the two human BBB models, and moderate to high in the animal BBB model. Efflux ratios (ER) calculated from bidirectional permeability experiments indicated that the compounds were likely not substrates of active efflux transporters. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative targeted proteomics for understanding the blood-brain barrier: towards pharmacoproteomics.

PubMed

Ohtsuki, Sumio; Hirayama, Mio; Ito, Shingo; Uchida, Yasuo; Tachikawa, Masanori; Terasaki, Tetsuya

2014-06-01

The blood-brain barrier (BBB) is formed by brain capillary endothelial cells linked together via complex tight junctions, and serves to prevent entry of drugs into the brain. Multiple transporters are expressed at the BBB, where they control exchange of materials between the circulating blood and brain interstitial fluid, thereby supporting and protecting the CNS. An understanding of the BBB is necessary for efficient development of CNS-acting drugs and to identify potential drug targets for treatment of CNS diseases. Quantitative targeted proteomics can provide detailed information on protein expression levels at the BBB. The present review highlights the latest applications of quantitative targeted proteomics in BBB research, specifically to evaluate species and in vivo-in vitro differences, and to reconstruct in vivo transport activity. Such a BBB quantitative proteomics approach can be considered as pharmacoproteomics.

Zika virus crosses an in vitro human blood brain barrier model.

PubMed

Alimonti, Judie B; Ribecco-Lutkiewicz, Maria; Sodja, Caroline; Jezierski, Anna; Stanimirovic, Danica B; Liu, Qing; Haqqani, Arsalan S; Conlan, Wayne; Bani-Yaghoub, Mahmud

2018-05-15

Zika virus (ZIKV) is a flavivirus that is highly neurotropic causing congenital abnormalities and neurological damage to the central nervous systems (CNS). In this study, we used a human induced pluripotent stem cell (iPSC)-derived blood brain barrier (BBB) model to demonstrate that ZIKV can infect brain endothelial cells (i-BECs) without compromising the BBB barrier integrity or permeability. Although no disruption to the BBB was observed post-infection, ZIKV particles were released on the abluminal side of the BBB model and infected underlying iPSC-derived neural progenitor cells (i-NPs). AXL, a putative ZIKV cellular entry receptor, was also highly expressed in ZIKV-susceptible i-BEC and i-NPs. This iPSC-derived BBB model can help elucidate the mechanism by which ZIKV can infect BECs, cross the BBB and gain access to the CNS.

Interleukin-1β transfer across the blood–brain barrier in the ovine fetus

PubMed Central

Sadowska, Grazyna B; Chen, Xiaodi; Zhang, Jiyong; Lim, Yow-Pin; Cummings, Erin E; Makeyev, Oleksandr; Besio, Walter G; Gaitanis, John; Padbury, James F; Banks, William A; Stonestreet, Barbara S

2015-01-01

Pro-inflammatory cytokines contribute to hypoxic–ischemic brain injury. Blood–brain barrier (BBB) dysfunction represents an important component of hypoxic–ischemic brain injury in the fetus. Hypoxic–ischemic injury could accentuate systemic cytokine transfer across the fetal BBB. There has been considerable conjecture suggesting that systemic cytokines could cross the BBB during the perinatal period. Nonetheless, evidence to support this contention is sparse. We hypothesized that ischemia–reperfusion increases the transfer of systemic interleukin-1β (IL-1β) across the BBB in the fetus. Ovine fetuses at 127 days of gestation were studied 4 hours after 30 minutes of bilateral carotid artery occlusion and compared with a nonischemic group. Recombinant ovine IL-1β protein was expressed from an IL-1β pGEX-2 T vector in E. coli BL-21 cells and purified. The BBB function was quantified in 12 brain regions using a blood-to-brain transfer constant with intravenous 125I-radiolabeled IL-1β (125I-IL-1β). Interleukin-1β crossed the intact BBB in nonischemic fetuses. Blood-to-brain transport of 125I-IL-1β was higher (P<0.05) across brain regions in fetuses exposed to ischemia–reperfusion than nonischemic fetuses. We conclude that systemic IL-1β crosses the intact fetal BBB, and that ischemia–reperfusion increases transfer of this cytokine across the fetal BBB. Therefore, altered BBB function after hypoxia–ischemia facilitates entry of systemic cytokines into the brain of the fetus. PMID:26082012

Interleukin-1β transfer across the blood-brain barrier in the ovine fetus.

PubMed

Sadowska, Grazyna B; Chen, Xiaodi; Zhang, Jiyong; Lim, Yow-Pin; Cummings, Erin E; Makeyev, Oleksandr; Besio, Walter G; Gaitanis, John; Padbury, James F; Banks, William A; Stonestreet, Barbara S

2015-09-01

Pro-inflammatory cytokines contribute to hypoxic-ischemic brain injury. Blood-brain barrier (BBB) dysfunction represents an important component of hypoxic-ischemic brain injury in the fetus. Hypoxic-ischemic injury could accentuate systemic cytokine transfer across the fetal BBB. There has been considerable conjecture suggesting that systemic cytokines could cross the BBB during the perinatal period. Nonetheless, evidence to support this contention is sparse. We hypothesized that ischemia-reperfusion increases the transfer of systemic interleukin-1β (IL-1β) across the BBB in the fetus. Ovine fetuses at 127 days of gestation were studied 4 hours after 30 minutes of bilateral carotid artery occlusion and compared with a nonischemic group. Recombinant ovine IL-1β protein was expressed from an IL-1β pGEX-2 T vector in E. coli BL-21 cells and purified. The BBB function was quantified in 12 brain regions using a blood-to-brain transfer constant with intravenous (125)I-radiolabeled IL-1β ((125)I-IL-1β). Interleukin-1β crossed the intact BBB in nonischemic fetuses. Blood-to-brain transport of (125)I-IL-1β was higher (P<0.05) across brain regions in fetuses exposed to ischemia-reperfusion than nonischemic fetuses. We conclude that systemic IL-1β crosses the intact fetal BBB, and that ischemia-reperfusion increases transfer of this cytokine across the fetal BBB. Therefore, altered BBB function after hypoxia-ischemia facilitates entry of systemic cytokines into the brain of the fetus.

Novel hits for acetylcholinesterase inhibition derived by docking-based screening on ZINC database.

PubMed

Doytchinova, Irini; Atanasova, Mariyana; Valkova, Iva; Stavrakov, Georgi; Philipova, Irena; Zhivkova, Zvetanka; Zheleva-Dimitrova, Dimitrina; Konstantinov, Spiro; Dimitrov, Ivan

2018-12-01

The inhibition of the enzyme acetylcholinesterase (AChE) increases the levels of the neurotransmitter acetylcholine and symptomatically improves the affected cognitive function. In the present study, we searched for novel AChE inhibitors by docking-based virtual screening of the standard lead-like set of ZINC database containing more than 6 million small molecules using GOLD software. The top 10 best-scored hits were tested in vitro for AChE affinity, neurotoxicity, GIT and BBB permeability. The main pharmacokinetic parameters like volume of distribution, free fraction in plasma, total clearance, and half-life were predicted by previously derived models. Nine of the compounds bind to the enzyme with affinities from 0.517 to 0.735 µM, eight of them are non-toxic. All hits permeate GIT and BBB and bind extensively to plasma proteins. Most of them are low-clearance compounds. In total, seven of the 10 hits are promising for further lead optimisation. These are structures with ZINC IDs: 00220177, 44455618, 66142300, 71804814, 72065926, 96007907, and 97159977.

12 CFR Appendix B to Subpart A of... - Appendix B to Subpart A of Part 327

Code of Federal Regulations, 2011 CFR

2011-01-01

... Converted value Standard & Poor's: AAA 1.00 AA+ 1.05 AA 1.15 AA− 1.30 A+ 1.50 A 1.80 A− 2.20 BBB+ 2.70 BBB... worse 3.00 Fitch's: AAA 1.00 AA+ 1.05 AA 1.15 AA− 1.30 A+ 1.50 A 1.80 A− 2.20 BBB+ 2.70 BBB or worse 3...

Cerebral amyloid angiopathy, blood-brain barrier disruption and amyloid accumulation in SAMP8 mice.

PubMed

del Valle, Jaume; Duran-Vilaregut, Joaquim; Manich, Gemma; Pallàs, Mercè; Camins, Antoni; Vilaplana, Jordi; Pelegrí, Carme

2011-01-01

Cerebrovascular dysfunction and β-amyloid peptide deposition on the walls of cerebral blood vessels might be an early event in the development of Alzheimer's disease. Here we studied the time course of amyloid deposition in blood vessels and blood-brain barrier (BBB) disruption in the CA1 subzone of the hippocampus of SAMP8 mice and the association between these two variables. We also studied the association between the amyloid deposition in blood vessels and the recently described amyloid clusters in the parenchyma, as well as the association of these clusters with vessels in which the BBB is disrupted. SAMP8 mice showed greater amyloid deposition in blood vessels than age-matched ICR-CD1 control mice. Moreover, at 12 months of age the number of vessels with a disrupted BBB had increased in both strains, especially SAMP8 animals. At this age, all the vessels with amyloid deposition showed BBB disruption, but several capillaries with an altered BBB showed no amyloid on their walls. Moreover, amyloid clusters showed no spatial association with vessels with amyloid deposition, nor with vessels in which the BBB had been disrupted. Finally, we can conclude that vascular amyloid deposition seems to induce BBB alterations, but BBB disruption may also be due to other factors. Copyright © 2011 S. Karger AG, Basel.

New experimental models of the blood-brain barrier for CNS drug discovery

PubMed Central

Kaisar, Mohammad A.; Sajja, Ravi K.; Prasad, Shikha; Abhyankar, Vinay V.; Liles, Taylor; Cucullo, Luca

2017-01-01

Introduction The blood-brain barrier (BBB) is a dynamic biological interface which actively controls the passage of substances between the blood and the central nervous system (CNS). From a biological and functional standpoint, the BBB plays a crucial role in maintaining brain homeostasis inasmuch that deterioration of BBB functions are prodromal to many CNS disorders. Conversely, the BBB hinders the delivery of drugs targeting the brain to treat a variety of neurological diseases. Area covered This article reviews recent technological improvements and innovation in the field of BBB modeling including static and dynamic cell-based platforms, microfluidic systems and the use of stem cells and 3D printing technologies. Additionally, the authors laid out a roadmap for the integration of microfluidics and stem cell biology as a holistic approach for the development of novel in vitro BBB platforms. Expert opinion Development of effective CNS drugs has been hindered by the lack of reliable strategies to mimic the BBB and cerebrovascular impairments in vitro. Technological advancements in BBB modeling have fostered the development of highly integrative and quasi- physiological in vitro platforms to support the process of drug discovery. These advanced in vitro tools are likely to further current understanding of the cerebrovascular modulatory mechanisms. PMID:27782770

Delivery of Biologics Across the Blood-Brain Barrier with Molecular Trojan Horse Technology.

PubMed

Pardridge, William M

2017-12-01

Biologics are potential new therapeutics for many diseases of the central nervous system. Biologics include recombinant lysosomal enzymes, neurotrophins, decoy receptors, and therapeutic antibodies. These are large molecule drugs that do not cross the blood-brain barrier (BBB). All classes of biologics have been tested, without success, in clinical trials of brain disease over the last 25 years. In none of these past clinical trials was the biologic re-engineered to enable transport across the BBB. If the biologic does not cross the BBB, the drug cannot reach the target site in brain, and success in a clinical trial is not expected. Biologics can be re-engineered for BBB transport with the use of molecular Trojan horse technology. A BBB molecular Trojan horse is a monoclonal antibody (MAb) against an endogenous BBB receptor transporter, such as the insulin receptor or transferrin receptor. The receptor-specific MAb penetrates the brain via transport on the endogenous BBB receptor. The MAb acts as a molecular Trojan horse to deliver across the BBB the biologic pharmaceutical that is genetically fused to the MAb. The lead Trojan horse is a MAb against the human insulin receptor (HIR), and HIRMAb-derived fusion proteins have entered clinical trials for the treatment of brain disease.

The neuroprotective effect of treatment with curcumin in acute spinal cord injury: laboratory investigation.

PubMed

Kim, Kyoung-Tae; Kim, Myoung-Jin; Cho, Dae-Chul; Park, Seong-Hyun; Hwang, Jeong-Hyun; Sung, Joo-Kyung; Cho, Hee-Jung; Jeon, Younghoon

2014-01-01

The purpose of this study was investigating the effects of curcumin on the histological changes and functional recovery following spinal cord injury (SCI) in a rat model. Following either sham operation or SCI, 36 male Sprague-Dawley rats were distributed into three groups: sham group, curcumin-treated group, and vehicle-injected group. Locomotor function was assessed according to the Basso, Beattie, and Bresnahan (BBB) scale in rats who had received daily intraperitoneal injections of 200 mg/kg curcumin or an equivalent volume of vehicle for 7 days following SCI. The injured spinal cord was then examined histologically, including quantification of cavitation. BBB scores were significantly higher in rats receiving curcumin than receiving vehicle (P < 0.05). The cavity volume was significantly reduced in the curcumin group as compared to the control group (P = 0.039). Superoxide dismutase (SOD) activity was significantly elevated in the curcumin group as compared to the vehicle group but was not significantly different from the sham group (P < 0.05, P > 0.05, respectively) at one and two weeks after SCI. Malondialdehyde (MDA) levels were significantly elevated in the vehicle group as compared to the sham group (P < 0.05 at 1 and 2 weeks). MDA activity was significantly reduced in the curcumin group at 2 weeks after SCI when compared to the vehicle group (P = 0.004). The numbers of macrophage were significantly decreased in the curcumin group (P = 0.001). This study demonstrated that curcumin enhances early functional recovery after SCI by diminishing cavitation volume, anti-inflammatory reactions, and antioxidant activity.

Combinatorial Approaches for the Identification of Brain Drug Delivery Targets

PubMed Central

Stutz, Charles C.; Zhang, Xiaobin; Shusta, Eric V.

2018-01-01

The blood-brain barrier (BBB) represents a large obstacle for the treatment of central nervous system diseases. Targeting endogenous nutrient transporters that transcytose the BBB is one promising approach to selectively and noninvasively deliver a drug payload to the brain. The main limitations of the currently employed transcytosing receptors are their ubiquitous expression in the peripheral vasculature and the inherent low levels of transcytosis mediated by such systems. In this review, approaches designed to increase the repertoire of transcytosing receptors which can be targeted for the purpose of drug delivery are discussed. In particular, combinatorial protein libraries can be screened on BBB cells in vitro or in vivo to isolate targeting peptides or antibodies that can trigger transcytosis. Once these targeting reagents are discovered, the cognate BBB transcytosis system can be identified using techniques such as expression cloning or immunoprecipitation coupled with mass spectrometry. Continued technological advances in BBB genomics and proteomics, membrane protein manipulation, and in vitro BBB technology promise to further advance the capability to identify and optimize peptides and antibodies capable of mediating drug transport across the BBB. PMID:23789958

Peptides and the blood–brain barrier

PubMed Central

Banks, William A.

2016-01-01

The demonstration that peptides and regulatory proteins can cross the blood–brain barrier (BBB) is one of the major contributions of Dr. Abba J. Kastin. He was the first to propose that peptides could cross the BBB, the first to show that an endogenous peptide did so, and the first to describe a saturable transport system at the BBB for peptides. His work shows that in crossing the BBB, peptides and regulatory proteins act as informational molecules, informing the brain of peripheral events. Brain-to-blood passage helps to control levels of peptides with the brain and can deliver information in the brain-to-blood direction. He showed that the transporters for peptides and proteins are not static, but respond to developmental and physiological changes and are affected by disease states. As such, the BBB is adaptive to the needs of the CNS, but when that adaption goes awry, the BBB can be a cause of disease. The mechanisms by which peptides and proteins cross the BBB offer opportunities for drug delivery of these substances or their analogs to the brain in the treatment of diseases of the central nervous system. PMID:25805003

Fluorescein isothiocyanate (FITC)-Dextran Extravasation as a Measure of Blood-Brain Barrier Permeability

PubMed Central

Natarajan, Reka; Northrop, Nicole

2017-01-01

The blood-brain barrier (BBB) is formed in part by vascular endothelial cells that constitute the capillaries and microvessels of the brain. The function of this barrier is to maintain homeostasis within the brain microenvironment and buffer the brain from changes in the periphery. A dysfunction of the BBB would permit circulating molecules and pathogens typically restricted to the periphery to enter the brain and interfere with normal brain function. As increased permeability of the BBB is associated with several neuropathologies, it is important to have a reliable and sensitive method that determines BBB permeability and the degree of BBB disruption. A detailed protocol is presented for assessing the integrity of the BBB by transcardial perfusion of a 10,000 Da FITC labeled dextran molecule and its visualization to determine the degree of extravasation from brain microvessels. PMID:28398646

CD146 coordinates brain endothelial cell–pericyte communication for blood–brain barrier development

PubMed Central

Chen, Jianan; Luo, Yongting; Hui, Hui; Cai, Tanxi; Huang, Hongxin; Yang, Fuquan; Feng, Jing; Zhang, Jingjing; Yan, Xiyun

2017-01-01

The blood–brain barrier (BBB) establishes a protective interface between the central neuronal system and peripheral blood circulation and is crucial for homeostasis of the CNS. BBB formation starts when the endothelial cells (ECs) invade the CNS and pericytes are recruited to the nascent vessels during embryogenesis. Despite the essential function of pericyte–EC interaction during BBB development, the molecular mechanisms coordinating the pericyte–EC behavior and communication remain incompletely understood. Here, we report a single cell receptor, CD146, that presents dynamic expression patterns in the cerebrovasculature at the stages of BBB induction and maturation, coordinates the interplay of ECs and pericytes, and orchestrates BBB development spatiotemporally. In mouse brain, CD146 is first expressed in the cerebrovascular ECs of immature capillaries without pericyte coverage; with increased coverage of pericytes, CD146 could only be detected in pericytes, but not in cerebrovascular ECs. Specific deletion of Cd146 in mice ECs resulted in reduced brain endothelial claudin-5 expression and BBB breakdown. By analyzing mice with specific deletion of Cd146 in pericytes, which have defects in pericyte coverage and BBB integrity, we demonstrate that CD146 functions as a coreceptor of PDGF receptor-β to mediate pericyte recruitment to cerebrovascular ECs. Moreover, we found that the attached pericytes in turn down-regulate endothelial CD146 by secreting TGF-β1 to promote further BBB maturation. These results reveal that the dynamic expression of CD146 controls the behavior of ECs and pericytes, thereby coordinating the formation of a mature and stable BBB. PMID:28827364

Non-human primate skull effects on the cavitation detection threshold of FUS-induced blood-brain barrier opening

NASA Astrophysics Data System (ADS)

Wu, Shih-Ying; Tung, Yao-Sheng; Marquet, Fabrice; Chen, Cherry C.; Konofagou, Elisa E.

2012-11-01

Microbubble (MB)-assisted focused ultrasound is a promising technique for delivering drugs to the brain by noninvasively and transiently opening the blood-brain barrier (BBB), and monitoring BBB opening using passive cavitation detection (PCD) is critical in detecting its occurrence, extent as well as assessing its mechanism. One of the main obstacles in achieving those objectives in large animals is the transcranial attenuation. To study the effects, the cavitation response through the in-vitro non-human primate (NHP) skull was investigated. In-house manufactured lipid-shelled MB (medium diameter: 4-5 um) were injected into a 4-mm channel of a phantom below a degassed monkey skull. A hydrophone confocally aligned with the FUS transducer served as PCD during sonication (frequency: 0.50 MHz, peak rarefactional pressures: 0.05-0.60 MPa, pulse length: 100 cycles, PRF: 10 Hz, duration: 2 s) for four cases: water without skull, water with skull, MB without skull and MB with skull. A 5.1-MHz linear-array transducer was also used to monitor the MB disruption. The frequency spectra, spectrograms, stable cavitation dose (SCD) and inertial cavitation dose (ICD) were quantified. Results showed that the onset of stable cavitation and inertial cavitation in the experiments occurred at 50 kPa, and was detectable throught the NHP skull since the both the detection thresholds for stable cavitation and inertial cavitation remained unchanged compared to the non-skull case, and the SCD and ICD acquired transcranially may not adequately represent the true extent of stable and inertial cavitation due to the skull attenuation.

Therapeutics for Brain Metastases, v3.

PubMed

Steeg, Patricia S; Zimmer, Alexandra; Gril, Brunilde

2016-12-15

The role of blood-brain barrier (BBB) permeability in the efficacy of brain metastasis therapeutics is debated. Both BBB-permeable and BBB-impermeable compounds were compared in a melanoma brain metastasis model using imaging through a cranial window. Only the BBB-permeable compound inhibited both the ∼30% permeable metastases and the ∼70% impermeable metastases. Clin Cancer Res; 22(24); 5953-5. ©2016 AACRSee related article by Osswald et al., p. 6078. ©2016 American Association for Cancer Research.

Current Strategies for Brain Drug Delivery

PubMed Central

Dong, Xiaowei

2018-01-01

The blood-brain barrier (BBB) has been a great hurdle for brain drug delivery. The BBB in healthy brain is a diffusion barrier essential for protecting normal brain function by impeding most compounds from transiting from the blood to the brain; only small molecules can cross the BBB. Under certain pathological conditions of diseases such as stroke, diabetes, seizures, multiple sclerosis, Parkinson's disease and Alzheimer disease, the BBB is disrupted. The objective of this review is to provide a broad overview on current strategies for brain drug delivery and related subjects from the past five years. It is hoped that this review could inspire readers to discover possible approaches to deliver drugs into the brain. After an initial overview of the BBB structure and function in both healthy and pathological conditions, this review re-visits, according to recent publications, some questions that are controversial, such as whether nanoparticles by themselves could cross the BBB and whether drugs are specifically transferred to the brain by actively targeted nanoparticles. Current non-nanoparticle strategies are also reviewed, such as delivery of drugs through the permeable BBB under pathological conditions and using non-invasive techniques to enhance brain drug uptake. Finally, one particular area that is often neglected in brain drug delivery is the influence of aging on the BBB, which is captured in this review based on the limited studies in the literature. PMID:29556336

Brain microvascular endothelial-astrocyte cell responses following Japanese encephalitis virus infection in an in vitro human blood-brain barrier model.

PubMed

Patabendige, Adjanie; Michael, Benedict D; Craig, Alister G; Solomon, Tom

2018-06-01

Japanese encephalitis virus (JEV) remains a leading cause of encephalitis, globally, which continues to grow in importance despite the availability of vaccines. Viral entry into the brain can occur via the blood-brain barrier (BBB), and inflammation at the BBB is a common final pathway in many brain infections. However, the role of the BBB during JEV infection and the contribution of the endothelial and astrocytic cell inflammation in facilitating virus entry into the brain are incompletely understood. We established a BBB model using human brain endothelial cells (HBECs) and human astrocytes. HBECs are polarised, and therefore the model was inoculated by JEV from the apical side to simulate the in vivo situation. The effects of JEV on the BBB permeability and release of inflammatory mediators from both apical and basolateral sides, representing the blood and the brain side respectively were investigated. JEV infected HBECs with limited active virus production, before crossing the BBB and infecting astrocytes. Control of JEV production by HBECs was associated with a significant increase in permeability, and with elevation of many host mediators, including cytokines, chemokines, cellular adhesion molecules, and matrix metalloproteases. When compared to the controls, significantly higher amounts of mediators were released from the apical side as opposed to the basolateral side. The increased release of mediators over time also correlated with increased BBB permeability. Treatment with dexamethasone led to a significant reduction in the release of interleukin 6 (IL6), C-C motif chemokine ligand 5 (CCL5) and C-X-C motif chemokine ligand 10 (CXCL10) from the apical side with a reduction in BBB disruption and no change in JEV production. The results are consistent with the hypothesis that JEV infection of the BBB triggers the production of a range of host mediators from both endothelial cells and astrocytes, which control JEV production but disrupt BBB integrity thus allowing virus entry into the brain. Dexamethasone treatment controlled the host response and limited BBB disruption in the model without increasing JEV production, supporting a re-investigation of its use therapeutically. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Transfection of brain capillary endothelial cells in primary culture with defined blood-brain barrier properties.

PubMed

Burkhart, Annette; Thomsen, Louiza Bohn; Thomsen, Maj Schneider; Lichota, Jacek; Fazakas, Csilla; Krizbai, István; Moos, Torben

2015-08-07

Primary brain capillary endothelial cells (BCECs) are a promising tool to study the blood-brain barrier (BBB) in vitro, as they maintain many important characteristics of the BBB in vivo, especially when co-cultured with pericytes and/or astrocytes. A novel strategy for drug delivery to the brain is to transform BCECs into protein factories by genetic modifications leading to secretion of otherwise BBB impermeable proteins into the central nervous system. However, a huge challenge underlying this strategy is to enable transfection of non-mitotic BCECs, taking a non-viral approach. We therefore aimed to study transfection in primary, non-mitotic BCECs cultured with defined BBB properties without disrupting the cells' integrity. Primary cultures of BCECs, pericytes and astrocytes were generated from rat brains and used in three different in vitro BBB experimental arrangements, which were characterised based on a their expression of tight junction proteins and other BBB specific proteins, high trans-endothelial electrical resistance (TEER), and low passive permeability to radiolabeled mannitol. Recombinant gene expression and protein synthesis were examined in primary BCECs. The BCECs were transfected using a commercially available transfection agent Turbofect™ to express the red fluorescent protein HcRed1-C1. The BCECs were transfected at different time points to monitor transfection in relation to mitotic or non-mitotic cells, as indicated by fluorescence-activated cell sorting analysis after 5-and 6-carboxylfluorescein diacetate succinidyl ester incorporation. The cell cultures exhibited important BBB characteristics judged from their expression of BBB specific proteins, high TEER values, and low passive permeability. Among the three in vitro BBB models, co-culturing with BCECs and astrocytes was well suited for the transfection studies. Transfection was independent of cell division and with equal efficacy between the mitotic and non-mitotic BCECs. Importantly, transfection of BCECs exhibiting BBB characteristics did not alter the integrity of the BCECs cell layer. The data clearly indicate that non-viral gene therapy of BCECs is possible in primary culture conditions with an intact BBB.

From nose to brain: understanding transport capacity and transport rate of drugs.

PubMed

Wu, Hongbing; Hu, Kaili; Jiang, Xinguo

2008-10-01

The unique relationship between nasal cavity and cranial cavity tissues in anatomy and physiology makes intranasal delivery to the brain feasible. An intranasal delivery provides some drugs with short channels to bypass the blood-brain barrier (BBB), especially for those with fairly low brain concentrations after a routine delivery, thus greatly enhancing the therapeutic effect on brain diseases. In the past two decades, a good number of encouraging outcomes have been reported in the treatment of diseases of the brain or central nervous system (CNS) through nasal administration. In spite of the significant merit of bypassing the BBB, direct nose-to-brain delivery still bears the problems of low efficiency and volume for capacity due to the limited volume of the nasal cavity, the small area ratio of olfactory mucosa to nasal mucosa and the limitations of low dose and short retention time of drug absorption. It is crucial that selective distribution and retention time of drugs or preparations on olfactory mucosa should be enhanced so as to increase the direct delivery efficiency. In this article, we first briefly review the nose-to-brain transport pathways, before detailing the impacts on them, followed by a comprehensive summary of effective methods, including formulation modification, agglutinant-mediated transport and a brain-homing, peptide-mediated delivery based on phage display screening technique, with a view to providing a theoretic reference for elevating the therapeutic effects on brain diseases.

Modeling the role of microglia during neurovascular development (WC10)

EPA Science Inventory

Microglia, resident brain macrophages, have important roles in blood-brain barrier (BBB) development and during focal BBB disruption. We reconstructed these complex dynamics utilizing computational and molecular methods: 1) constructing a systems map of BBB development from known...

Trafficking of adeno-associated virus vectors across a model of the blood-brain barrier; a comparative study of transcytosis and transduction using primary human brain endothelial cells.

PubMed

Merkel, Steven F; Andrews, Allison M; Lutton, Evan M; Mu, Dakai; Hudry, Eloise; Hyman, Bradley T; Maguire, Casey A; Ramirez, Servio H

2017-01-01

Developing therapies for central nervous system (CNS) diseases is exceedingly difficult because of the blood-brain barrier (BBB). Notably, emerging technologies may provide promising new options for the treatment of CNS disorders. Adeno-associated virus serotype 9 (AAV9) has been shown to transduce cells in the CNS following intravascular administration in rodents, cats, pigs, and non-human primates. These results suggest that AAV9 is capable of crossing the BBB. However, mechanisms that govern AAV9 transendothelial trafficking at the BBB remain unknown. Furthermore, possibilities that AAV9 may transduce brain endothelial cells or affect BBB integrity still require investigation. Using primary human brain microvascular endothelial cells as a model of the human BBB, we performed transduction and transendothelial trafficking assays comparing AAV9 to AAV2, a serotype that does not cross the BBB or transduce endothelial cells effectively in vivo. Results of our in vitro studies indicate that AAV9 penetrates brain microvascular endothelial cells barriers more effectively than AAV2, but has reduced transduction efficiency. In addition, our data suggest that (i) AAV9 penetrates endothelial barriers through an active, cell-mediated process, and (ii) AAV9 fails to disrupt indicators of BBB integrity such as transendothelial electrical resistance, tight junction protein expression/localization, and inflammatory activation status. Overall, this report shows how human brain endothelial cells configured in BBB models can be utilized for evaluating transendothelial movement and transduction kinetics of various AAV capsids. Importantly, the use of a human in vitro BBB model can provide import insight into the possible effects that candidate AVV gene therapy vectors may have on the status of BBB integrity. Read the Editorial Highlight for this article on page 192. © 2016 International Society for Neurochemistry.

Blood-Brain Barrier Disruption After Cardiopulmonary Bypass: Diagnosis and Correlation to Cognition.

PubMed

Abrahamov, Dan; Levran, Oren; Naparstek, Sharon; Refaeli, Yael; Kaptson, Shani; Abu Salah, Mahmud; Ishai, Yaron; Sahar, Gideon

2017-07-01

Cardiopulmonary bypass (CPB) elicits a systemic inflammatory response that may impair blood-brain barrier (BBB) integrity. BBB disruption can currently be detected by dynamic contrast enhancement magnetic resonance imaging (MRI), reflected by an increase in the permeability constant (K trans ). We aimed to determine (1) whether CPB induces BBB disruption, (2) duration until BBB disruption resolution, and (3) the obtainable correlation between BBB injury (location and intensity) and neurocognitive dysfunction. Seven patients undergoing CPB with coronary artery bypass grafting (CABG) were assigned to serial cerebral designated MRI evaluations, preoperatively and on postoperative day (POD) 1 and 5. Examinations were analyzed for BBB disruption and microemboli using dynamic contrast enhancement MRI and diffusion-weighted imaging methods, respectively. Neuropsychologic tests were performed 1 day preoperatively and on POD 5. A significant local K trans increase (0.03 min -1 vs 0.07 min -1 , p = 0.033) compatible with BBB disruption was evident in 5 patients (71%) on POD 1. Resolution was observed by POD 5 (mean, 0.012 min -1 ). The location of the disruption was most prominent in the frontal lobes (400% vs 150% K trans levels upsurge, p = 0.05). MRI evidence of microembolization was demonstrated in only 1 patient (14%). The postoperative global cognitive score was reduced in all patients (98.2 ± 12 vs 95.1 ± 11, p = 0.032), predominantly in executive and attention (frontal lobe-related) functions (91.8 ± 13 vs 86.9 ± 12, p = 0.042). The intensity of the dynamic contrast enhancement MRI BBB impairment correlated with the magnitude of cognition reduction (r = 0.69, p = 0.04). BBB disruption was evident in most patients, primarily in the frontal lobes. The location and intensity of the BBB disruption, rather than the microembolic load, correlated with postoperative neurocognitive dysfunction. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Rapamycin decreased blood-brain barrier permeability in control but not in diabetic rats in early cerebral ischemia.

PubMed

Chi, Oak Z; Kiss, Geza K; Mellender, Scott J; Liu, Xia; Weiss, Harvey R

2017-07-27

Diabetes causes functional and structural changes in blood-brain barrier (BBB). The mammalian target of rapamycin (mTOR) has been associated with glucose metabolism, diabetes, and altering BBB permeability. Since there is only a narrow therapeutic window (3h) for stroke victims, it is important to investigate BBB disruption in the early stage of cerebral ischemia. We compared the degree of BBB disruption in diabetic and in control rats at two hours of reperfusion after one hour of middle cerebral artery (MCA) occlusion with or without inhibition of mTOR. Two weeks after streptozotocin ip to induce diabetes, MCA occlusion was performed. In half of the rats, an mTOR inhibitor, rapamycin was given for 2days before MCA occlusion. After one hour of MCA occlusion and two hours of the reperfusion, the transfer coefficient (K i ) of 14 C-α-aminoisobutyric acid was determined to quantify degree of BBB disruption. Ischemia-reperfusion increased the K i in the control animals. Streptozotocin increased the K i in the ischemic-reperfused (IR-C, +22%) as well as in the contralateral cortex (CC, +40%). Rapamycin decreased the K i in the IR-C (-32%) as well as in the CC (-26%) in the control rats. However, rapamycin did not affect K i in the IR-C or in the CC in the diabetic rats. Our data demonstrated a greater BBB disruption in diabetes in the ischemic as well as non-ischemic cortex even in the early stage of cerebral ischemia-reperfusion and that acute administration of rapamycin did not significantly affect BBB permeability in diabetes. From our quantitative analysis of BBB disruption, the vulnerability of BBB in diabetes has been emphasized in the early stage of cerebral ischemia-reperfusion and a less important role of the mTOR pathway is suggested in altering BBB permeability in diabetes. Copyright © 2017 Elsevier B.V. All rights reserved.

Blood-brain barrier disruption induced by diagnostic ultrasound combined with microbubbles in mice.

PubMed

Zhao, Bingxia; Chen, Yihan; Liu, Jinfeng; Zhang, Li; Wang, Jing; Yang, Yali; Lv, Qing; Xie, Mingxing

2018-01-12

To investigate the effects of the microbubble (MB) dose, mechanism index (MI) and sonication duration on blood-brain barrier (BBB) disruption induced by diagnostic ultrasound combined with MBs as well as to investigate the potential molecular mechanism. The extent of BBB disruption increased with MB dose, MI and sonication duration. A relatively larger extent of BBB disruption associated with minimal tissue damage was achieved by an appropriate MB dose and ultrasound exposure parameters with diagnostic ultrasound. Decreased expression of ZO-1, occludin and claudin-5 were correlated with disruption of the BBB, as confirmed by paracellular passage of the tracer lanthanum nitrate into the brain parenchyma after BBB disruption. These findings indicated that this technique is a promising tool for promoting brain delivery of diagnostic and therapeutic agents in the diagnosis and treatment of brain diseases. The extent of BBB disruption was qualitatively assessed by Evans blue (EB) staining and quantitatively analyzed by an EB extravasation measurement. A histological examination was performed to evaluate tissue damage. Expression of tight junction (TJ) related proteins ZO-1, occludin and claudin-5 was determined by western blotting analysis and immunohistofluorescence. Transmission electron microscopy was performed to observe ultrastructure changes of TJs after BBB disruption.

Assessment of Blood-brain Barrier Permeability by Intravenous Infusion of FITC-labeled Albumin in a Mouse Model of Neurodegenerative Disease.

PubMed

Di Pardo, Alba; Castaldo, Salvatore; Capocci, Luca; Amico, Enrico; Vittorio, Maglione

2017-11-08

Disruption of blood-brain barrier (BBB) integrity is a common feature for different neurological and neurodegenerative diseases. Although the interplay between perturbed BBB homeostasis and the pathogenesis of brain disorders needs further investigation, the development and validation of a reliable procedure to accurately detect BBB alterations may be crucial and represent a useful tool for potentially predicting disease progression and developing targeted therapeutic strategies. Here, we present an easy and efficient procedure for evaluating BBB leakage in a neurodegenerative condition like that occurring in a preclinical mouse model of Huntington disease, in which defects in the permeability of BBB are clearly detectable precociously in the disease. Specifically, the high molecular weight fluorescein isothiocyanate labelled (FITC)-albumin, which is able to cross the BBB only when the latter is impaired, is acutely infused into a mouse jugular vein and its distribution in the vascular or parenchymal districts is then determined by fluorescence microscopy. Accumulation of green fluorescent-albumin in the brain parenchyma functions as an index of aberrant BBB permeability and, when quantitated by using Image J processing software, is reported as Green Fluorescence Intensity.

Peptides and the blood-brain barrier.

PubMed

Banks, William A

2015-10-01

The demonstration that peptides and regulatory proteins can cross the blood-brain barrier (BBB) is one of the major contributions of Dr. Abba J. Kastin. He was the first to propose that peptides could cross the BBB, the first to show that an endogenous peptide did so, and the first to describe a saturable transport system at the BBB for peptides. His work shows that in crossing the BBB, peptides and regulatory proteins act as informational molecules, informing the brain of peripheral events. Brain-to-blood passage helps to control levels of peptides with the brain and can deliver information in the brain-to-blood direction. He showed that the transporters for peptides and proteins are not static, but respond to developmental and physiological changes and are affected by disease states. As such, the BBB is adaptive to the needs of the CNS, but when that adaption goes awry, the BBB can be a cause of disease. The mechanisms by which peptides and proteins cross the BBB offer opportunities for drug delivery of these substances or their analogs to the brain in the treatment of diseases of the central nervous system. Published by Elsevier Inc.

Magnetic resonance imaging indicators of blood-brain barrier and brain water changes in young rats with kaolin-induced hydrocephalus.

PubMed

Del Bigio, Marc R; Slobodian, Ili; Schellenberg, Angela E; Buist, Richard J; Kemp-Buors, Tanya L

2011-08-11

Hydrocephalus is associated with enlargement of cerebral ventricles. We hypothesized that magnetic resonance (MR) imaging parameters known to be influenced by tissue water content would change in parallel with ventricle size in young rats and that changes in blood-brain barrier (BBB) permeability would be detected. Hydrocephalus was induced by injection of kaolin into the cisterna magna of 4-week-old rats, which were studied 1 or 3 weeks later. MR was used to measure longitudinal and transverse relaxation times (T1 and T2) and apparent diffusion coefficients in several regions. Brain tissue water content was measured by the wet-dry weight method, and tissue density was measured in Percoll gradient columns. BBB permeability was measured by quantitative imaging of changes on T1-weighted images following injection of gadolinium diethylenetriamine penta-acetate (Gd-DTPA) tracer and microscopically by detection of fluorescent dextran conjugates. In nonhydrocephalic rats, water content decreased progressively from age 3 to 7 weeks. T1 and T2 and apparent diffusion coefficients did not exhibit parallel changes and there was no evidence of BBB permeability to tracers. The cerebral ventricles enlarged progressively in the weeks following kaolin injection. In hydrocephalic rats, the dorsal cortex was more dense and the white matter less so, indicating that the increased water content was largely confined to white matter. Hydrocephalus was associated with transient elevation of T1 in gray and white matter and persistent elevation of T2 in white matter. Changes in the apparent diffusion coefficients were significant only in white matter. Ventricle size correlated significantly with dorsal water content, T1, T2, and apparent diffusion coefficients. MR imaging showed evidence of Gd-DTPA leakage in periventricular tissue foci but not diffusely. These correlated with microscopic leak of larger dextran tracers. MR characteristics cannot be used as direct surrogates for water content in the immature rat model of hydrocephalus, probably because they are also influenced by other changes in tissue composition that occur during brain maturation. There is no evidence for widespread persistent opening of BBB as a consequence of hydrocephalus in young rats. However, increase in focal BBB permeability suggests that periventricular blood vessels may be disrupted.

[Peripheral neuropathy and blood-nerve barrier].

PubMed

Kanda, Takashi

2009-11-01

It is important to know the cellular properties of endoneurial microvascular endothelial cells (PnMECs) and microvascular pericytes which constitute blood-nerve barrier (BNB), since this barrier structure in the peripheral nervous system (PNS) may play pivotal pathophysiological roles in various disorders of the PNS including inflammatory neuropathies (i.e. Guillain-Barré syndrome), vasculitic neuropathies, hereditary neuropathies and diabetic neuropathy. However, in contrast to blood-brain barrier (BBB), very few studies have been directed to BNB and no adequate cell lines originating from BNB had been launched. In our laboratory, we successfully established human immortalized cell lines originating from BNB using temperature-sensitive SV40 large T antigen and the cellular properties of human cell lines are presented in this paper. Human PnMEC cell line showed high transendothelial electrical resistance and expressed tight junction components and various types of influx as well as efflux transporters that have been reported to function at BBB. Human pericyte cell line also possessed tight junction proteins except claudin-5 and secrete various cytokines and growth factors including bFGF, VEGF, GDNF, NGF, BDNF and angiopoietin-1. Co-culture with pericytes or pericyte-conditioned media strengthend barrier properties of PnMEC, suggesting that in the PNS, peripheral nerve pericytes support the BNB function and play the same role of astrocytes in the BBB. Future accumulation of the knowledge concerning the cellular properties of BNB-forming cells will open the door to novel therapeutic strategies for intractable peripheral neuropathies.

Étude de la perméabilité de la barrière hémato-encéphalique par microdialyse après irradiation photonique monofractionnée chez le rat

NASA Astrophysics Data System (ADS)

Agin, A.; Martin, C.; Mauris, J.; Staali, F.; Diserbo, M.

1999-01-01

The effects of total-body irradiation on the permeability of rat striatal blood-brain barrier (BBB) to [ ^3H] aminoisobutyric acid (AIBA) and [ 14C] sucrose were investigated. Seven days, 6 weeks, 3 and 5 months after gamma exposure at the dose of 4.5 Gy, no modification of the permeability to both [ ^3H] AIBA and [ 14C] sucrose was observed. A transient “opening" of the BBB to [ 14C] sucrose was noticed about 28 hours following irradiation. The transport of [3H] AIBA through BBB was decreased between the 33^th and the 47^th post-radiation hour. Nous avons étudié, dans le striatum de rat, les effets d'une irradiation globale aiguë sur la perméabilité de la barrière hémato-encéphalique à l'acide [ ^3H] aminoisobutyrique et au [ 14C] saccharose. Sept jours, 6 semaines, 3 et 5 mois après exposition γ à la dose de 4,5 Gy, aucune altération de la perméabilité aux deux marqueurs n'a été observée. Une “ouverture" transitoire de la BHE au [ 14C] saccharose est notée vers la 28e heure suivant l'irradiation. Le transport du [ ^3H] aminoisobutyrate est diminué entre 33 et 47 heures après irradiation.

High-Throughput Screening for Identification of Blood-Brain Barrier Integrity Enhancers: A Drug Repurposing Opportunity to Rectify Vascular Amyloid Toxicity.

PubMed

Qosa, Hisham; Mohamed, Loqman A; Al Rihani, Sweilem B; Batarseh, Yazan S; Duong, Quoc-Viet; Keller, Jeffrey N; Kaddoumi, Amal

2016-07-06

The blood-brain barrier (BBB) is a dynamic interface that maintains brain homeostasis and protects it from free entry of chemicals, toxins, and drugs. The barrier function of the BBB is maintained mainly by capillary endothelial cells that physically separate brain from blood. Several neurological diseases, such as Alzheimer's disease (AD), are known to disrupt BBB integrity. In this study, a high-throughput screening (HTS) was developed to identify drugs that rectify/protect BBB integrity from vascular amyloid toxicity associated with AD progression. Assessing Lucifer Yellow permeation across in-vitro BBB model composed from mouse brain endothelial cells (bEnd3) grown on 96-well plate inserts was used to screen 1280 compounds of Sigma LOPAC®1280 library for modulators of bEnd3 monolayer integrity. HTS identified 62 compounds as disruptors, and 50 compounds as enhancers of the endothelial barrier integrity. From these 50 enhancers, 7 FDA approved drugs were identified with EC50 values ranging from 0.76-4.56 μM. Of these 7 drugs, 5 were able to protect bEnd3-based BBB model integrity against amyloid toxicity. Furthermore, to test the translational potential to humans, the 7 drugs were tested for their ability to rectify the disruptive effect of Aβ in the human endothelial cell line hCMEC/D3. Only 3 (etodolac, granisetron, and beclomethasone) out of the 5 effective drugs in the bEnd3-based BBB model demonstrated a promising effect to protect the hCMEC/D3-based BBB model integrity. These drugs are compelling candidates for repurposing as therapeutic agents that could rectify dysfunctional BBB associated with AD.

High-throughput screening for identification of blood-brain barrier integrity enhancers: a drug repurposing opportunity to rectify vascular amyloid toxicity

PubMed Central

Qosa, Hisham; Mohamed, Loqman A.; Al Rihani, Sweilem B.; Batarseh, Yazan S.; Duong, Quoc-Viet; Keller, Jeffrey N.; Kaddoumi, Amal

2016-01-01

The blood-brain barrier (BBB) is a dynamic interface that maintains brain homeostasis and protects it from free entry of chemicals, toxins and drugs. The barrier function of the BBB is maintained mainly by capillary endothelial cells that physically separate brain from blood. Several neurological diseases, such as Alzheimer’s disease (AD), are known to disrupt BBB integrity. In this study, a high-throughput screening (HTS) was developed to identify drugs that rectify/protect BBB integrity from vascular amyloid toxicity associated with AD progression. Assessing Lucifer Yellow permeation across in-vitro BBB model composed from mouse brain endothelial cells (bEnd3) grown on 96-well plate inserts was used to screen 1280 compounds of Sigma LOPAC®1280 library for modulators of bEnd3 monolayer integrity. HTS identified 62 compounds as disruptors, and 50 compounds as enhancers of the endothelial barrier integrity. From these 50 enhancers, 7 FDA approved drugs were identified with EC50 values ranging from 0.76–4.56 μM. Of these 7 drugs, five were able to protect bEnd3-based BBB model integrity against amyloid toxicity. Furthermore, to test the translational potential to humans, the 7 drugs were tested for their ability to rectify the disruptive effect of Aβ in the human endothelial cell line hCMEC/D3. Only 3 (etodolac, granisetron and beclomethasone) out of the 5 effective drugs in the bEnd3-based BBB model demonstrated a promising effect to protect the hCMEC/D3-based BBB model integrity. These drugs are compelling candidates for repurposing as therapeutic agents that could rectify dysfunctional BBB associated with AD. PMID:27392852

The role of the blood-brain barrier in the development and treatment of migraine and other pain disorders.

PubMed

DosSantos, Marcos F; Holanda-Afonso, Rosenilde C; Lima, Rodrigo L; DaSilva, Alexandre F; Moura-Neto, Vivaldo

2014-01-01

The function of the blood-brain barrier (BBB) related to chronic pain has been explored for its classical role in regulating the transcellular and paracellular transport, thus controlling the flow of drugs that act at the central nervous system, such as opioid analgesics (e.g., morphine) and non-steroidal anti-inflammatory drugs. Nonetheless, recent studies have raised the possibility that changes in the BBB permeability might be associated with chronic pain. For instance, changes in the relative amounts of occludin isoforms, resulting in significant increases in the BBB permeability, have been demonstrated after inflammatory hyperalgesia. Furthermore, inflammatory pain produces structural changes in the P-glycoprotein, the major efflux transporter at the BBB. One possible explanation for these findings is the action of substances typically released at the site of peripheral injuries that could lead to changes in the brain endothelial permeability, including substance P, calcitonin gene-related peptide, and interleukin-1 beta. Interestingly, inflammatory pain also results in microglial activation, which potentiates the BBB damage. In fact, astrocytes and microglia play a critical role in maintaining the BBB integrity and the activation of those cells is considered a key mechanism underlying chronic pain. Despite the recent advances in the understanding of BBB function in pain development as well as its interference in the efficacy of analgesic drugs, there remain unknowns regarding the molecular mechanisms involved in this process. In this review, we explore the connection between the BBB as well as the blood-spinal cord barrier and blood-nerve barrier, and pain, focusing on cellular and molecular mechanisms of BBB permeabilization induced by inflammatory or neuropathic pain and migraine.

The role of the blood–brain barrier in the development and treatment of migraine and other pain disorders

PubMed Central

DosSantos, Marcos F.; Holanda-Afonso, Rosenilde C.; Lima, Rodrigo L.; DaSilva, Alexandre F.; Moura-Neto, Vivaldo

2014-01-01

The function of the blood–brain barrier (BBB) related to chronic pain has been explored for its classical role in regulating the transcellular and paracellular transport, thus controlling the flow of drugs that act at the central nervous system, such as opioid analgesics (e.g., morphine) and non-steroidal anti-inflammatory drugs. Nonetheless, recent studies have raised the possibility that changes in the BBB permeability might be associated with chronic pain. For instance, changes in the relative amounts of occludin isoforms, resulting in significant increases in the BBB permeability, have been demonstrated after inflammatory hyperalgesia. Furthermore, inflammatory pain produces structural changes in the P-glycoprotein, the major efflux transporter at the BBB. One possible explanation for these findings is the action of substances typically released at the site of peripheral injuries that could lead to changes in the brain endothelial permeability, including substance P, calcitonin gene-related peptide, and interleukin-1 beta. Interestingly, inflammatory pain also results in microglial activation, which potentiates the BBB damage. In fact, astrocytes and microglia play a critical role in maintaining the BBB integrity and the activation of those cells is considered a key mechanism underlying chronic pain. Despite the recent advances in the understanding of BBB function in pain development as well as its interference in the efficacy of analgesic drugs, there remain unknowns regarding the molecular mechanisms involved in this process. In this review, we explore the connection between the BBB as well as the blood–spinal cord barrier and blood–nerve barrier, and pain, focusing on cellular and molecular mechanisms of BBB permeabilization induced by inflammatory or neuropathic pain and migraine. PMID:25339863

Inhibitory effects of alcohol on glucose transport across the blood-brain barrier leads to neurodegeneration: preventive role of acetyl-L: -carnitine.

PubMed

Abdul Muneer, P M; Alikunju, Saleena; Szlachetka, Adam M; Haorah, James

2011-04-01

Evidence shows that alcohol intake causes oxidative neuronal injury and neurocognitive deficits that are distinct from the classical Wernicke-Korsakoff neuropathy. Our previous findings indicated that alcohol-elicited blood-brain barrier (BBB) damage leads to neuroinflammation and neuronal loss. The dynamic function of the BBB requires a constant supply and utilization of glucose. Here we examined whether interference of glucose uptake and transport at the endothelium by alcohol leads to BBB dysfunction and neuronal degeneration. We tested the hypothesis in cell culture of human brain endothelial cells, neurons and alcohol intake in animal by immunofluorescence, Western blotting and glucose uptake assay methods. We found that decrease in glucose uptake correlates the reduction of glucose transporter protein 1 (GLUT1) in cell culture after 50 mM ethanol exposure. Decrease in GLUT1 protein levels was regulated at the translation process. In animal, chronic alcohol intake suppresses the transport of glucose into the frontal and occipital regions of the brain. This finding is validated by a marked decrease in GLUT1 protein expression in brain microvessel (the BBB). In parallel, alcohol intake impairs the BBB tight junction proteins occludin, zonula occludens-1, and claudin-5 in the brain microvessel. Permeability of sodium fluorescein and Evans Blue confirms the leakiness of the BBB. Further, depletion of trans-endothelial electrical resistance of the cell monolayer supports the disruption of BBB integrity. Administration of acetyl-L: -carnitine (a neuroprotective agent) significantly prevents the adverse effects of alcohol on glucose uptake, BBB damage and neuronal degeneration. These findings suggest that alcohol-elicited inhibition of glucose transport at the blood-brain interface leads to BBB malfunction and neurological complications.

Selection of a Relevant In Vitro Blood-Brain Barrier Model to Investigate Pro-Metastatic Features of Human Breast Cancer Cell Lines.

PubMed

Drolez, Aurore; Vandenhaute, Elodie; Julien, Sylvain; Gosselet, Fabien; Burchell, Joy; Cecchelli, Roméo; Delannoy, Philippe; Dehouck, Marie-Pierre; Mysiorek, Caroline

2016-01-01

Around 7-17% of metastatic breast cancer patients will develop brain metastases, associated with a poor prognosis. To reach the brain parenchyma, cancer cells need to cross the highly restrictive endothelium of the Blood-Brain Barrier (BBB). As treatments for brain metastases are mostly inefficient, preventing cancer cells to reach the brain could provide a relevant and important strategy. For that purpose an in vitro approach is required to identify cellular and molecular interaction mechanisms between breast cancer cells and BBB endothelium, notably at the early steps of the interaction. However, while numerous studies are performed with in vitro models, the heterogeneity and the quality of BBB models used is a limitation to the extrapolation of the obtained results to in vivo context, showing that the choice of a model that fulfills the biological BBB characteristics is essential. Therefore, we compared pre-established and currently used in vitro models from different origins (bovine, mice, human) in order to define the most appropriate tool to study interactions between breast cancer cells and the BBB. On each model, the BBB properties and the adhesion capacities of breast cancer cell lines were evaluated. As endothelial cells represent the physical restriction site of the BBB, all the models consisted of endothelial cells from animal or human origins. Among these models, only the in vitro BBB model derived from human stem cells both displayed BBB properties and allowed measurement of meaningful different interaction capacities of the cancer cell lines. Importantly, the measured adhesion and transmigration were found to be in accordance with the cancer cell lines molecular subtypes. In addition, at a molecular level, the inhibition of ganglioside biosynthesis highlights the potential role of glycosylation in breast cancer cells adhesion capacities.

Localized delivery of low-density lipoprotein docosahexaenoic acid nanoparticles to the rat brain using focused ultrasound.

PubMed

Mulik, Rohit S; Bing, Chenchen; Ladouceur-Wodzak, Michelle; Munaweera, Imalka; Chopra, Rajiv; Corbin, Ian R

2016-03-01

Focused ultrasound exposures in the presence of microbubbles can achieve transient, non-invasive, and localized blood-brain barrier (BBB) opening, offering a method for targeted delivery of therapeutic agents into the brain. Low-density lipoprotein (LDL) nanoparticles reconstituted with docosahexaenoic acid (DHA) could have significant therapeutic value in the brain, since DHA is known to be neuroprotective. BBB opening was achieved using pulsed ultrasound exposures in a localized brain region in normal rats, after which LDL nanoparticles containing the fluorescent probe DiR (1,1'-Dioctadecyl-3,3,3',3'-Tetramethylindotricarbocyanine Iodide) or DHA were administered intravenously. Fluorescent imaging of brain tissue from rats administered LDL-DiR demonstrated strong localization of fluorescence signal in the exposed hemisphere. LDL-DHA administration produced 2 × more DHA in the exposed region of the brain, with a corresponding increase in Resolvin D1 levels, indicating DHA was incorporated into cells and metabolized. Histological evaluation did not indicate any evidence of increased tissue damage in exposed brain regions compared to normal brain. This work demonstrates that localized delivery of DHA to the brain is possible using systemically-administered LDL nanoparticles combined with pulsed focused ultrasound exposures in the brain. This technology could be used in regions of acute brain injury or as a means to target infiltrating tumor cells in the brain. Copyright © 2016 Elsevier Ltd. All rights reserved.

Localized Delivery of Low-Density Lipoprotein Docosahexaenoic Acid Nanoparticles to the Rat Brain using Focused Ultrasound

PubMed Central

Mulik, Rohit S.; Bing, Chenchen; Ladouceur-Wodzak, Michelle; Munaweera, Imalka; Chopra, Rajiv; Corbin, Ian R.

2016-01-01

Focused ultrasound exposures in the presence of microbubbles can achieve transient, non-invasive, and localized blood-brain barrier (BBB) opening, offering a method for targeted delivery of therapeutic agents into the brain. Low-density lipoprotein (LDL) nanoparticles reconstituted with docosahexaenoic acid (DHA) could have significant therapeutic value in the brain, since DHA is known to be neuroprotective. BBB opening was achieved using pulsed ultrasound exposures in a localized brain region in normal rats, after which LDL nanoparticles containing the fluorescent probe DiR (1,1′-Dioctadecyl-3,3,3′,3′-Tetramethylindotricarbocyanine Iodide) or DHA were administered intravenously. Fluorescent imaging of brain tissue from rats administered LDL-DiR demonstrated strong localization of fluorescence signal in the exposed hemisphere. LDL-DHA administration produced 2× more DHA in the exposed region of the brain, with a corresponding increase in Resolvin D1 levels, indicating DHA was incorporated into cells and metabolized. Histological evaluation did not indicate any evidence of increased tissue damage in exposed brain regions compared to normal brain. This work demonstrates that localized delivery of DHA to the brain is possible using systemically-administered LDL nanoparticles combined with pulsed focused ultrasound exposures in the brain. This technology could be used in regions of acute brain injury or as a means to target infiltrating tumor cells in the brain. PMID:26790145

Effects of deferoxamine on blood-brain barrier disruption after subarachnoid hemorrhage.

PubMed

Li, Yanjiang; Yang, Heng; Ni, Wei; Gu, Yuxiang

2017-01-01

Blood brain barrier (BBB) disruption is a key mechanism of subarachnoid hemorrhage (SAH)-induced brain injury. This study examined the mechanism of iron-induced BBB disruption after SAH and investigated the potential therapeutic effect of iron chelation on SAH. Male adult Sprague-Dawley rats had an endovascular perforation of left internal carotid artery bifurcation or sham operation. The rats were treated with deferoxamine (DFX) or vehicle (100mg/kg) for a maximum of 7 days. Brain edema, BBB leakage, behavioral and cognitive impairment were examined. In SAH rat, the peak time of brain edema and BBB impairment in the cortex was at day 3 after SAH. SAH resulted in a significant increase in ferritin expression in the cortex. The ferritin positive cells were colocalized with endothelial cells, pericytes, astrocytes, microglia and neurons. Compared with vehicle, DFX caused less ferritin upregulation, brain water content, BBB impairment, behavioral and cognitive deficits in SAH rats. The results suggest iron overload could be a therapeutic target for SAH induced BBB damage.

Tick-borne encephalitis virus infects human brain microvascular endothelial cells without compromising blood-brain barrier integrity.

PubMed

Palus, Martin; Vancova, Marie; Sirmarova, Jana; Elsterova, Jana; Perner, Jan; Ruzek, Daniel

2017-07-01

Alteration of the blood-brain barrier (BBB) is a hallmark of tick-borne encephalitis (TBE), a life-threating human viral neuroinfection. However, the mechanism of BBB breakdown during TBE, as well as TBE virus (TBEV) entry into the brain is unclear. Here, primary human microvascular endothelial cells (HBMECs) were infected with TBEV to study interactions with the BBB. Although the number of infected cells was relatively low in culture (<5%), the infection was persistent with high TBEV yields (>10 6 pfu/ml). Infection did not induce any significant changes in the expression of key tight junction proteins or upregulate the expression of cell adhesion molecules, and did not alter the highly organized intercellular junctions between HBMECs. In an in vitro BBB model, the virus crossed the BBB via a transcellular pathway without compromising the integrity of the cell monolayer. The results indicate that HBMECs may support TBEV entry into the brain without altering BBB integrity. Copyright © 2017 Elsevier Inc. All rights reserved.

Blood-brain barrier dysfunction in mice induced by lipopolysaccharide is attenuated by dapsone.

PubMed

Zhou, Ting; Zhao, Lei; Zhan, Rui; He, Qihua; Tong, Yawei; Tian, Xiaosheng; Wang, Hecheng; Zhang, Tao; Fu, Yaoyun; Sun, Yang; Xu, Feng; Guo, Xiangyang; Fan, Dongsheng; Han, Hongbin; Chui, Dehua

2014-10-24

Blood-brain barrier (BBB) dysfunction is a key event in the development of many central nervous system (CNS) diseases, such as septic encephalopathy and stroke. 4,4'-Diaminodiphenylsulfone (DDS, Dapsone) has displayed neuroprotective effect, but whether DDS has protective role on BBB integrity is not clear. This study was designed to examine the effect of DDS on lipopolysaccharide (LPS)-induced BBB disruption and oxidative stress in brain vessels. Using in vivo multiphoton imaging, we found that DDS administration significantly restored BBB integrity compromised by LPS. DDS also increased the expression of tight junction proteins occludin, zona occludens-1 (ZO-1) and claudin-5 in brain vessels. Level of reactive oxygen species (ROS) was reduced by DDS treatment, which may due to decreased nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and NOX2 expression. Our results showed that LPS-induced BBB dysfunction could be attenuated by DDS, indicated that DDS has a therapeutic potential for treating CNS infection and other BBB related diseases. Copyright © 2014 Elsevier Inc. All rights reserved.

Differentiation and characterization of human pluripotent stem cell-derived brain microvascular endothelial cells.

PubMed

Stebbins, Matthew J; Wilson, Hannah K; Canfield, Scott G; Qian, Tongcheng; Palecek, Sean P; Shusta, Eric V

2016-05-15

The blood-brain barrier (BBB) is a critical component of the central nervous system (CNS) that regulates the flux of material between the blood and the brain. Because of its barrier properties, the BBB creates a bottleneck to CNS drug delivery. Human in vitro BBB models offer a potential tool to screen pharmaceutical libraries for CNS penetration as well as for BBB modulators in development and disease, yet primary and immortalized models respectively lack scalability and robust phenotypes. Recently, in vitro BBB models derived from human pluripotent stem cells (hPSCs) have helped overcome these challenges by providing a scalable and renewable source of human brain microvascular endothelial cells (BMECs). We have demonstrated that hPSC-derived BMECs exhibit robust structural and functional characteristics reminiscent of the in vivo BBB. Here, we provide a detailed description of the methods required to differentiate and functionally characterize hPSC-derived BMECs to facilitate their widespread use in downstream applications. Copyright © 2015 Elsevier Inc. All rights reserved.

Nanoparticle accumulation and transcytosis in brain endothelial cell layers

NASA Astrophysics Data System (ADS)

Ye, Dong; Raghnaill, Michelle Nic; Bramini, Mattia; Mahon, Eugene; Åberg, Christoffer; Salvati, Anna; Dawson, Kenneth A.

2013-10-01

The blood-brain barrier (BBB) is a selective barrier, which controls and limits access to the central nervous system (CNS). The selectivity of the BBB relies on specialized characteristics of the endothelial cells that line the microvasculature, including the expression of intercellular tight junctions, which limit paracellular permeability. Several reports suggest that nanoparticles have a unique capacity to cross the BBB. However, direct evidence of nanoparticle transcytosis is difficult to obtain, and we found that typical transport studies present several limitations when applied to nanoparticles. In order to investigate the capacity of nanoparticles to access and transport across the BBB, several different nanomaterials, including silica, titania and albumin- or transferrin-conjugated gold nanoparticles of different sizes, were exposed to a human in vitro BBB model of endothelial hCMEC/D3 cells. Extensive transmission electron microscopy imaging was applied in order to describe nanoparticle endocytosis and typical intracellular localisation, as well as to look for evidence of eventual transcytosis. Our results show that all of the nanoparticles were internalised, to different extents, by the BBB model and accumulated along the endo-lysosomal pathway. Rare events suggestive of nanoparticle transcytosis were also observed for several of the tested materials.The blood-brain barrier (BBB) is a selective barrier, which controls and limits access to the central nervous system (CNS). The selectivity of the BBB relies on specialized characteristics of the endothelial cells that line the microvasculature, including the expression of intercellular tight junctions, which limit paracellular permeability. Several reports suggest that nanoparticles have a unique capacity to cross the BBB. However, direct evidence of nanoparticle transcytosis is difficult to obtain, and we found that typical transport studies present several limitations when applied to nanoparticles. In order to investigate the capacity of nanoparticles to access and transport across the BBB, several different nanomaterials, including silica, titania and albumin- or transferrin-conjugated gold nanoparticles of different sizes, were exposed to a human in vitro BBB model of endothelial hCMEC/D3 cells. Extensive transmission electron microscopy imaging was applied in order to describe nanoparticle endocytosis and typical intracellular localisation, as well as to look for evidence of eventual transcytosis. Our results show that all of the nanoparticles were internalised, to different extents, by the BBB model and accumulated along the endo-lysosomal pathway. Rare events suggestive of nanoparticle transcytosis were also observed for several of the tested materials. Electronic supplementary information (ESI) available: Nanoparticle characterization in relevant media by Dynamic Light Scattering and SDS-PAGE. Transport study for silica nanoparticles across the BBB layer. Additional Electron Microscopy images of cells treated with the different nanoparticles investigated and details of the filters of the transwell systems. See DOI: 10.1039/c3nr02905k

Enhanced Delivery of Gold Nanoparticles with Therapeutic Potential for Targeting Human Brain Tumors

NASA Astrophysics Data System (ADS)

Etame, Arnold B.

The blood brain barrier (BBB) remains a major challenge to the advancement and application of systemic anti-cancer therapeutics into the central nervous system. The structural and physiological delivery constraints of the BBB significantly limit the effectiveness of conventional chemotherapy, thereby making systemic administration a non-viable option for the vast majority of chemotherapy agents. Furthermore, the lack of specificity of conventional systemic chemotherapy when applied towards malignant brain tumors remains a major shortcoming. Hence novel therapeutic strategies that focus both on targeted and enhanced delivery across the BBB are warranted. In recent years nanoparticles (NPs) have emerged as attractive vehicles for efficient delivery of targeted anti-cancer therapeutics. In particular, gold nanoparticles (AuNPs) have gained prominence in several targeting applications involving systemic cancers. Their enhanced permeation and retention within permissive tumor microvasculature provide a selective advantage for targeting. Malignant brain tumors also exhibit transport-permissive microvasculature secondary to blood brain barrier disruption. Hence AuNPs may have potential relevance for brain tumor targeting. However, the permeation of AuNPs across the BBB has not been well characterized, and hence is a potential limitation for successful application of AuNP-based therapeutics within the central nervous system (CNS). In this dissertation, we designed and characterized AuNPs and assessed the role of polyethylene glycol (PEG) on the physical and biological properties of AuNPs. We established a size-dependent permeation profile with respect to core size as well as PEG length when AuNPs were assessed through a transport-permissive in-vitro BBB. This study was the first of its kind to systematically examine the influence of design on permeation of AuNPs through transport-permissive BBB. Given the significant delivery limitations through the non-transport permissive and intact BBB, we also assessed the role of magnetic resonance imaging (MRI) guided focused ultrasound (MRgFUS) disruption of the BBB in enhancing permeation of AuNPs across the intact BBB and tumor BBB in vivo. MRgFUS is a novel technique that can transiently increase BBB permeability thereby allowing delivery of therapeutics into the CNS. We demonstrated enhanced delivery of AuNPs with therapeutic potential into the CNS via MRgFUS. Our study was the first to establish a definitive role for MRgFUS in delivering AuNPs into the CNS. In summary, this thesis describes results from a series of research projects that have contributed to our understanding of the influence of design features on AuNP permeation through the BBB and also the potential role of MRgFUS in AuNP permeation across the BBB.

Role of nitric oxide synthases in early blood-brain barrier disruption following transient focal cerebral ischemia.

PubMed

Jiang, Zheng; Li, Chun; Arrick, Denise M; Yang, Shu; Baluna, Alexandra E; Sun, Hong

2014-01-01

The role of nitric oxide synthases (NOSs) in early blood-brain barrier (BBB) disruption was determined using a new mouse model of transient focal cerebral ischemia. Ischemia was induced by ligating the middle cerebral artery (MCA) at its M2 segment and reperfusion was induced by releasing the ligation. The diameter alteration of the MCA, arterial anastomoses and collateral arteries were imaged and measured in real time. BBB disruption was assessed by Evans Blue (EB) and sodium fluorescein (Na-F) extravasation at 3 hours of reperfusion. The reperfusion produced an extensive vasodilation and a sustained hyperemia. Although expression of NOSs was not altered at 3 hours of reperfusion, L-NAME (a non-specific NOS inhibitor) abolished reperfusion-induced vasodilation/hyperemia and significantly reduced EB and Na-F extravasation. L-NIO (an endothelial NOS (eNOS) inhibitor) significantly attenuated cerebral vasodilation but not BBB disruption, whereas L-NPA and 7-NI (neuronal NOS (nNOS) inhibitors) significantly reduced BBB disruption but not cerebral vasodilation. In contrast, aminoguanidine (AG) (an inducible NOS (iNOS) inhibitor) had less effect on either cerebral vasodilation or BBB disruption. On the other hand, papaverine (PV) not only increased the vasodilation/hyperemia but also significantly reduced BBB disruption. Combined treatment with L-NAME and PV preserved the vasodilation/hyperemia and significantly reduced BBB disruption. Our findings suggest that nNOS may play a major role in early BBB disruption following transient focal cerebral ischemia via a hyperemia-independent mechanism.

Insights into the Effects of Complement Factor H on the Assembly and Decay of the Alternative Pathway C3 Proconvertase and C3 Convertase*

PubMed Central

Bettoni, Serena; Bresin, Elena; Remuzzi, Giuseppe; Noris, Marina; Donadelli, Roberta

2016-01-01

The activated fragment of C3 (C3b) and factor B form the C3 proconvertase (C3bB), which is cleaved by factor D to C3 convertase (C3bBb). Older studies (Conrad, D. H., Carlo, J. R., and Ruddy, S. (1978) J. Exp. Med. 147, 1792–1805; Pangburn, M. K., and Müller-Eberhard, H. J. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 2416–2420; Kazatchkine, M. D., Fearon, D. T., and Austen, K. F. (1979) J. Immunol. 122, 75–81) indicated that the complement alternative pathway regulator factor H (FH) competes with factor B for C3b binding; however, the capability of FH to prevent C3bB assembly has not been formally investigated. Moreover, in the few published studies FH did not favor C3bB dissociation. Whether FH may affect C3bBb formation from C3bB is unknown. We set up user-friendly assays based on combined microplate/Western blotting techniques that specifically detect either C3bB or C3bBb, with the aim of investigating the effect of FH on C3bB assembly and decay and C3bBb formation and decay. We document that FH does not affect C3bB assembly, indicating that FH does not efficiently compete with factor B for C3b binding. We also found that FH does not dissociate C3bB. FH showed a strong C3bBb decay-accelerating activity, as reported previously, and also exerted an apparent inhibitory effect on C3bBb formation. The latter effect was not fully attributable to a rapid FH-mediated dissociation of C3bBb complexes, because blocking decay with properdin and C3 nephritic factor did not restore C3bBb formation. FH almost completely prevented release of the smaller cleavage subunit of FB (Ba), without modifying the amount of C3bB complexes, suggesting that FH inhibits the conversion of C3bB to C3bBb. Thus, the inhibitory effect of FH on C3bBb formation is likely the sum of inhibition of C3bB conversion to C3bBb and of C3bBb decay acceleration. Further studies are required to confirm these findings in physiological cell-based settings. PMID:26903516

Viral Infection of the Central Nervous System and Neuroinflammation Precede Blood-Brain Barrier Disruption during Japanese Encephalitis Virus Infection.

PubMed

Li, Fang; Wang, Yueyun; Yu, Lan; Cao, Shengbo; Wang, Ke; Yuan, Jiaolong; Wang, Chong; Wang, Kunlun; Cui, Min; Fu, Zhen F

2015-05-01

Japanese encephalitis is an acute zoonotic, mosquito-borne disease caused by Japanese encephalitis virus (JEV). Japanese encephalitis is characterized by extensive inflammation in the central nervous system (CNS) and disruption of the blood-brain barrier (BBB). However, the pathogenic mechanisms contributing to the BBB disruption are not known. Here, using a mouse model of intravenous JEV infection, we show that virus titers increased exponentially in the brain from 2 to 5 days postinfection. This was accompanied by an early, dramatic increase in the level of inflammatory cytokines and chemokines in the brain. Enhancement of BBB permeability, however, was not observed until day 4, suggesting that viral entry and the onset of inflammation in the CNS occurred prior to BBB damage. In vitro studies revealed that direct infection with JEV could not induce changes in the permeability of brain microvascular endothelial cell monolayers. However, brain extracts derived from symptomatic JEV-infected mice, but not from mock-infected mice, induced significant permeability of the endothelial monolayer. Consistent with a role for inflammatory mediators in BBB disruption, the administration of gamma interferon-neutralizing antibody ameliorated the enhancement of BBB permeability in JEV-infected mice. Taken together, our data suggest that JEV enters the CNS, propagates in neurons, and induces the production of inflammatory cytokines and chemokines, which result in the disruption of the BBB. Japanese encephalitis (JE) is the leading cause of viral encephalitis in Asia, resulting in 70,000 cases each year, in which approximately 20 to 30% of cases are fatal, and a high proportion of patients survive with serious neurological and psychiatric sequelae. Pathologically, JEV infection causes an acute encephalopathy accompanied by BBB dysfunction; however, the mechanism is not clear. Thus, understanding the mechanisms of BBB disruption in JEV infection is important. Our data demonstrate that JEV gains entry into the CNS prior to BBB disruption. Furthermore, it is not JEV infection per se, but the inflammatory cytokines/chemokines induced by JEV infection that inhibit the expression of TJ proteins and ultimately result in the enhancement of BBB permeability. Neutralization of gamma interferon (IFN-γ) ameliorated the enhancement of BBB permeability in JEV-infected mice, suggesting that IFN-γ could be a potential therapeutic target. This study would lead to identification of potential therapeutic avenues for the treatment of JEV infection. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Synthesis and Evaluation of Neuroprotective Selenoflavanones

PubMed Central

Choi, Yong-Sung; Kim, Dong-Myung; Kim, Yoon-Jung; Yang, Sai; Lee, Kyung-Tae; Ryu, Jong Hoon; Jeong, Jin-Hyun

2015-01-01

The physicochemical properties and antioxidant activity of a molecule could be improved by the substitution of an oxygen atom in a molecule with selenium. We synthesized selenoflavanones and flavanones to evaluate their neuroprotective effects. The selenoflavanones showed improved physicochemical properties, suggestive of the ability to pass through the blood-brain barrier (BBB). They showed in vitro antioxidant effects against hydrogen peroxide, and did not result in severe cytotoxicity. Moreover, infarction volumes in a transient ischemia mouse model were significantly reduced by the selenoflavanone treatments. PMID:26690420

Blood-brain barrier disruption induced by diagnostic ultrasound combined with microbubbles in mice

PubMed Central

Liu, Jinfeng; Zhang, Li; Wang, Jing; Yang, Yali; Lv, Qing; Xie, Mingxing

2018-01-01

Objective To investigate the effects of the microbubble (MB) dose, mechanism index (MI) and sonication duration on blood-brain barrier (BBB) disruption induced by diagnostic ultrasound combined with MBs as well as to investigate the potential molecular mechanism. Results The extent of BBB disruption increased with MB dose, MI and sonication duration. A relatively larger extent of BBB disruption associated with minimal tissue damage was achieved by an appropriate MB dose and ultrasound exposure parameters with diagnostic ultrasound. Decreased expression of ZO-1, occludin and claudin-5 were correlated with disruption of the BBB, as confirmed by paracellular passage of the tracer lanthanum nitrate into the brain parenchyma after BBB disruption. Conclusions These findings indicated that this technique is a promising tool for promoting brain delivery of diagnostic and therapeutic agents in the diagnosis and treatment of brain diseases. Methods The extent of BBB disruption was qualitatively assessed by Evans blue (EB) staining and quantitatively analyzed by an EB extravasation measurement. A histological examination was performed to evaluate tissue damage. Expression of tight junction (TJ) related proteins ZO-1, occludin and claudin-5 was determined by western blotting analysis and immunohistofluorescence. Transmission electron microscopy was performed to observe ultrastructure changes of TJs after BBB disruption. PMID:29435150

Astrocytic modulation of blood brain barrier: perspectives on Parkinson's disease.

PubMed

Cabezas, Ricardo; Avila, Marcos; Gonzalez, Janneth; El-Bachá, Ramon Santos; Báez, Eliana; García-Segura, Luis Miguel; Jurado Coronel, Juan Camilo; Capani, Francisco; Cardona-Gomez, Gloria Patricia; Barreto, George E

2014-01-01

The blood-brain barrier (BBB) is a tightly regulated interface in the Central Nervous System (CNS) that regulates the exchange of molecules in and out from the brain thus maintaining the CNS homeostasis. It is mainly composed of endothelial cells (ECs), pericytes and astrocytes that create a neurovascular unit (NVU) with the adjacent neurons. Astrocytes are essential for the formation and maintenance of the BBB by providing secreted factors that lead to the adequate association between the cells of the BBB and the formation of strong tight junctions. Under neurological disorders, such as chronic cerebral ischemia, brain trauma, Epilepsy, Alzheimer and Parkinson's Diseases, a disruption of the BBB takes place, involving a lost in the permeability of the barrier and phenotypical changes in both the ECs and astrocytes. In this aspect, it has been established that the process of reactive gliosis is a common feature of astrocytes during BBB disruption, which has a detrimental effect on the barrier function and a subsequent damage in neuronal survival. In this review we discuss the implications of astrocyte functions in the protection of the BBB, and in the development of Parkinson's disease (PD) and related disorders. Additionally, we highlight the current and future strategies in astrocyte protection aimed at the development of restorative therapies for the BBB in pathological conditions.

Re-engineering therapeutic antibodies for Alzheimer's disease as blood-brain barrier penetrating bi-specific antibodies.

PubMed

Pardridge, William M

2016-12-01

Therapeutic antibodies are large molecule drugs that do not cross the blood-brain barrier (BBB). Therefore, drug development of therapeutic antibodies for Alzheimer's disease (AD) requires that these molecules be re-engineered to enable BBB delivery. This is possible by joining the therapeutic antibody with a transporter antibody, resulting in the engineering of a BBB-penetrating bispecific antibody (BSA). Areas covered: The manuscript covers transporter antibodies that cross the BBB via receptor-mediated transport systems on the BBB, such as the insulin receptor or transferrin receptor. Furthermore, it highlights therapeutic antibodies for AD that target the Abeta amyloid peptide, beta secretase-1, or the metabotropic glutamate receptor-1. BSAs are comprised of both the transporter antibody and the therapeutic antibody, as well as IgG constant region, which can induce immune tolerance or trigger transport via Fc receptors. Expert opinion: Multiple types of BSA molecular designs have been used to engineer BBB-penetrating BSAs, which differ in valency and spatial orientation of the transporter and therapeutic domains of the BSA. The plasma pharmacokinetics and dosing regimens of BSAs differ from that of conventional therapeutic antibodies. BBB-penetrating BSAs may be engineered in the future as new treatments of AD, as well as other neural disorders.

Endothelial β-Catenin Signaling Is Required for Maintaining Adult Blood-Brain Barrier Integrity and CNS Homeostasis

PubMed Central

Tran, Khiem A.; Zhang, Xianming; Predescu, Dan; Huang, Xiaojia; Machado, Roberto F.; Göthert, Joachim R.; Malik, Asrar B.; Valyi-Nagy, Tibor; Zhao, You-Yang

2015-01-01

Background The blood-brain barrier (BBB) formed by brain endothelial cells (ECs) interconnected by tight junctions (TJs) is essential for the homeostasis of the central nervous system (CNS). Although studies have shown the importance of various signaling molecules in BBB formation during development, little is known about the molecular basis regulating the integrity of the adult BBB. Methods and Results Using a mouse model with tamoxifen-inducible EC-restricted disruption of ctnnb1 (iCKO), here we show that endothelial β-catenin signaling is essential for maintaining BBB integrity and CNS homeostasis in adult. The iCKO mice developed severe seizures accompanied by neuronal injury, multiple brain petechial hemorrhages, and CNS inflammation, and all died postictal. Disruption of endothelial β-catenin induced BBB breakdown and downregulation of specific TJ proteins Claudin-1 and -3 in adult brain ECs. The clinical relevance of the data is indicated by the observation of decreased expression of Claudin-1 and nuclear β-catenin in brain ECs of hemorrhagic lesions of hemorrhagic stroke patients. Conclusion These results demonstrate the prerequisite role of endothelial β-catenin in maintaining the integrity of adult BBB. The results suggest that BBB dysfunction secondary to defective β-catenin transcription activity is a key pathogenic factor in hemorrhagic stroke, seizure activity and CNS inflammation. PMID:26538583

Safety and maximum tolerated dose of superselective intraarterial cerebral infusion of bevacizumab after osmotic blood-brain barrier disruption for recurrent malignant glioma. Clinical article.

PubMed

Boockvar, John A; Tsiouris, Apostolos J; Hofstetter, Christoph P; Kovanlikaya, Ilhami; Fralin, Sherese; Kesavabhotla, Kartik; Seedial, Stephen M; Pannullo, Susan C; Schwartz, Theodore H; Stieg, Philip; Zimmerman, Robert D; Knopman, Jared; Scheff, Ronald J; Christos, Paul; Vallabhajosula, Shankar; Riina, Howard A

2011-03-01

The authors assessed the safety and maximum tolerated dose of superselective intraarterial cerebral infusion (SIACI) of bevacizumab after osmotic disruption of the blood-brain barrier (BBB) with mannitol in patients with recurrent malignant glioma. A total of 30 patients with recurrent malignant glioma were included in the current study. The authors report no dose-limiting toxicity from a single dose of SIACI of bevacizumab up to 15 mg/kg after osmotic BBB disruption with mannitol. Two groups of patients were studied; those without prior bevacizumab exposure (naïve patients; Group I) and those who had received previous intravenous bevacizumab (exposed patients; Group II). Radiographic changes demonstrated on MR imaging were assessed at 1 month postprocedure. In Group I patients, MR imaging at 1 month showed a median reduction in the area of tumor enhancement of 34.7%, a median reduction in the volume of tumor enhancement of 46.9%, a median MR perfusion (MRP) reduction of 32.14%, and a T2-weighted/FLAIR signal decrease in 9 (47.4%) of 19 patients. In Group II patients, MR imaging at 1 month showed a median reduction in the area of tumor enhancement of 15.2%, a median volume reduction of 8.3%, a median MRP reduction of 25.5%, and a T2-weighted FLAIR decrease in 0 (0%) of 11 patients. The authors conclude that SIACI of mannitol followed by bevacizumab (up to 15 mg/kg) for recurrent malignant glioma is safe and well tolerated. Magnetic resonance imaging shows that SIACI treatment with bevacizumab can lead to reduction in tumor area, volume, perfusion, and T2-weighted/FLAIR signal.

Prediction of infarction development after endovascular stroke therapy with dual-energy computed tomography.

PubMed

Djurdjevic, Tanja; Rehwald, Rafael; Knoflach, Michael; Matosevic, Benjamin; Kiechl, Stefan; Gizewski, Elke Ruth; Glodny, Bernhard; Grams, Astrid Ellen

2017-03-01

After intraarterial recanalisation (IAR), the haemorrhage and the blood-brain barrier (BBB) disruption can be distinguished using dual-energy computed tomography (DECT). The aim of the present study was to investigate whether future infarction development can be predicted from DECT. DECT scans of 20 patients showing 45 BBB disrupted areas after IAR were assessed and compared with follow-up examinations. Receiver operator characteristic (ROC) analyses using densities from the iodine map (IM) and virtual non-contrast (VNC) were performed. Future infarction areas are denser than future non-infarction areas on IM series (23.44 ± 24.86 vs. 5.77 ± 2.77; p < 0.0001) and more hypodense on VNC series (29.71 ± 3.33 vs. 35.33 ± 3.50; p < 0.0001). ROC analyses for the IM series showed an area under the curve (AUC) of 0.99 (cut-off: <9.97 HU; p < 0.05; sensitivity 91.18 %; specificity 100.00 %; accuracy 0.93) for the prediction of future infarctions. The AUC for the prediction of haemorrhagic infarctions was 0.78 (cut-off >17.13 HU; p < 0.05; sensitivity 90.00 %; specificity 62.86 %; accuracy 0.69). The VNC series allowed prediction of infarction volume. Future infarction development after IAR can be reliably predicted with the IM series. The prediction of haemorrhages and of infarction size is less reliable. • The IM series (DECT) can predict future infarction development after IAR. • Later haemorrhages can be predicted using the IM and the BW series. • The volume of definable hypodense areas in VNC correlates with infarction volume.

A novel implantable catheter system with transcutaneous port for intermittent convection-enhanced delivery of carboplatin for recurrent glioblastoma.

PubMed

Barua, Neil U; Hopkins, Kirsten; Woolley, Max; O'Sullivan, Stephen; Harrison, Rob; Edwards, Richard J; Bienemann, Alison S; Wyatt, Marcella J; Arshad, Azeem; Gill, Steven S

2016-01-01

Inadequate penetration of the blood-brain barrier (BBB) by systemically administered chemotherapies including carboplatin is implicated in their failure to improve prognosis for patients with glioblastoma. Convection-enhanced delivery (CED) of carboplatin has the potential to improve outcomes by facilitating bypass of the BBB. We report the first use of an implantable CED system incorporating a novel transcutaneous bone-anchored port (TBAP) for intermittent CED of carboplatin in a patient with recurrent glioblastoma. The CED catheter system was implanted using a robot-assisted surgical method. Catheter targeting accuracy was verified by performing intra-operative O-arm imaging. The TBAP was implanted using a skin-flap dermatome technique modeled on bone-anchored hearing aid surgery. Repeated infusions were performed by attaching a needle administration set to the TBAP. Drug distribution was monitored with serial real-time T2-weighted magnetic resonance imaging (MRI). All catheters were implanted to within 1.5 mm of their planned target. Intermittent infusions of carboplatin were performed on three consecutive days and repeated after one month without the need for further surgical intervention. Infused volumes of 27.9 ml per day were well tolerated, with the exception of a single seizure episode. Follow-up MRI at eight weeks demonstrated a significant reduction in the volume of tumor enhancement from 42.6 ml to 24.6 ml, and was associated with stability of the patient's clinical condition. Reduction in the volume of tumor enhancement indicates that intermittent CED of carboplatin has the potential to improve outcomes in glioblastoma. The novel technology described in this report make intermittent CED infusion regimes an achievable treatment strategy.

[Study of neuron-protective effect and mechanism of neuregulin1β against cerebral ischemia reperfusion-induced injury in rats].

PubMed

Ji, Y Q; Zhang, R; Teng, L; Li, H Y; Guo, Y L

2017-07-18

Objective: Thecurrent study is to explore the neuron-protective mechanism of neuregulin1β (NRG1β) in a rat model of middle cerebral artery occlusion/reperfusion (MCAO/R) through inhibiting the c-Jun phosphorylation. Methods: After 24 h of MCAO/R (referring to Longa's method), neurobehavioral function was measured by modified neurological severity score (mNSS) test; the cerebral infarction volume was detected by triphenyltetrazolium chloride (TTC) staining; the blood brain barrier (BBB) permeability was measured by Evans Blue (EB); the neuron morphology of brain tissue was observed by Nissl stain; the ultra-structures of the neurons were observed by transmission electron microscopy (TEM); the apoptotic neurons were counted by in situ cell death detection kit colocalized with NeuN; the expressions of phospho-c-Jun was determined by immunofluorescent labeling and Western blot analysis. Results: Compared with the sham-operation rats, the rats receiving MCAO/R showed increased mNSS (9.7±1.2), cerebral infarction volume (41.4±3.0)%, permeability of BBB, deformation of neurons, ischemia-induced apoptosis (0.63±0.04), and enhanced expression of phospho-c-Jun protein (0.90±0.07) (all P <0.05). Our data indicated that NRG1β attenuated neurologic deficits (6.4±0.9), decreased the cerebral infarction volume (10.4±0.5), reduced EB extravasation (1.55±0.13) and the deformation of neurons, protected the ultra-structure of neurons, blocked ischemia-induced apoptosis (0.23±0.02), through down-regulated phospho-c-Jun expression (0.40±0.03) in MCAO/R rats ( P <0.05). Conclusion: NRG1β exerts neuron-protective effects against ischemia reperfusion-induced injury in rats through inhibiting the c-Jun phosphorylation.

Blood-brain barrier permeation and efflux exclusion of anticholinergics used in the treatment of overactive bladder.

PubMed

Chancellor, Michael B; Staskin, David R; Kay, Gary G; Sandage, Bobby W; Oefelein, Michael G; Tsao, Jack W

2012-04-01

Overactive bladder (OAB) is a common condition, particularly in the elderly. Anticholinergic agents are the mainstay of pharmacological treatment of OAB; however, many anticholinergics can cross the blood-brain barrier (BBB) and may cause central nervous system (CNS) effects, including cognitive deficits, which can be especially detrimental in older patients. Many anticholinergics have the potential to cause adverse CNS effects due to muscarinic (M(1)) receptor binding in the brain. Of note, permeability of the BBB increases with age and can also be affected by trauma, stress, and some diseases and medications. Passive crossing of a molecule across the BBB into the brain is dependent upon its physicochemical properties. Molecular characteristics that hinder passive BBB penetration include a large molecular size, positive or negative ionic charge at physiological pH, and a hydrophilic structure. Active transport across the BBB is dependent upon protein-mediated transporter systems, such as that of permeability-glycoprotein (P-gp), which occurs only for P-gp substrates, such as trospium chloride, darifenacin and fesoterodine. Reliance on active transport can be problematic since genetic polymorphisms of P-gp exist, and many commonly used drugs and even some foods are P-gp inhibitors or are substrates themselves and, due to competition, can reduce the amount of the drug that is actively transported out of the CNS. Therefore, for drugs that are preferred not to cross into the CNS, such as potent anticholinergics intended for the bladder, it is optimal to have minimal passive crossing of the BBB, although it may also be beneficial for the drug to be a substrate for an active efflux transport system. Anticholinergics demonstrate different propensities to cross the BBB. Darifenacin, fesoterodine and trospium chloride are substrates for P-gp and, therefore, are actively transported away from the brain. In addition, trospium chloride has not been detected in cerebrospinal fluid assays and does not appear to have significant CNS penetration. This article reviews the properties of anticholinergics that affect BBB penetration and active transport out of the CNS, discusses issues of increased BBB permeability in patients with OAB, and examines the clinical implications of BBB penetration on adverse events associated with anticholinergics.

Curcumin by down-regulating NF-kB and elevating Nrf2, reduces brain edema and neurological dysfunction after cerebral I/R.

PubMed

Li, Wei; Suwanwela, Nijasri C; Patumraj, Suthiluk

2016-07-01

Oxidation, inflammation, and apoptosis are three critical factors for the pathogenic mechanism of cerebral ischemia/reperfusion (I/R) injury. Curcumin exhibits substantial biological properties via anti-oxidation, anti-inflammation and anti-apoptotic effects; however, the molecular mechanism underlying the effects of curcumin against cerebral I/R injury remains unclear. To investigate the effects of curcumin on cerebral I/R injury associated with water content, infarction volume, and the expression of nuclear factor-kappa-B (NF-κB) and nuclear factor-erythroid-related factor-2 (Nrf2). Middle cerebral artery occlusion (MCAO, 1-hour occlusion and 24-hour reperfusion) was performed in male Wistar rats (n=64) as a cerebral I/R injury model. In the MCAO+CUR group, the rats were administered curcumin (300mg/kg BW, i.p.) at 30min after occlusion. The same surgical procedures were performed in SHAM rats without MCAO occlusion. At 24h post-operation, the parameters, including neurological deficit scores, blood brain barrier (BBB) disruption, water content, and infarction volume, were determined. Brain tissue NF-κB and Nrf2 expression levels were assayed through immunohistochemistry. Compared with the SHAM group, BBB disruption, neurological deficit, and increased brain water content and infarction volume were markedly demonstrated in the MCAO group. NF-κB expression was enhanced in the MCAO group. However, in the MCAO+CUR group, the upregulation of Nrf2, an anti-oxidation related protein, was consistent with a significant decline in the water content, infarction volume, and NF-κB expression. The protective effects of curcumin against cerebral I/R injury reflect anti-oxidation, anti-inflammation and anti-apoptotic activities, resulting in the elevation of Nrf2 and down-regulation of NF-κB. Copyright © 2015 Elsevier Inc. All rights reserved.

Modeling Psychomotor Retardation using iPSCs from MCT8-Deficient Patients Indicates a Prominent Role for the Blood-Brain Barrier.

PubMed

Vatine, Gad D; Al-Ahmad, Abraham; Barriga, Bianca K; Svendsen, Soshana; Salim, Ariel; Garcia, Leslie; Garcia, Veronica J; Ho, Ritchie; Yucer, Nur; Qian, Tongcheng; Lim, Ryan G; Wu, Jie; Thompson, Leslie M; Spivia, Weston R; Chen, Zhaohui; Van Eyk, Jennifer; Palecek, Sean P; Refetoff, Samuel; Shusta, Eric V; Svendsen, Clive N

2017-06-01

Inactivating mutations in the thyroid hormone (TH) transporter Monocarboxylate transporter 8 (MCT8) cause severe psychomotor retardation in children. Animal models do not reflect the biology of the human disease. Using patient-specific induced pluripotent stem cells (iPSCs), we generated MCT8-deficient neural cells that showed normal TH-dependent neuronal properties and maturation. However, the blood-brain barrier (BBB) controls TH entry into the brain, and reduced TH availability to neural cells could instead underlie the diseased phenotype. To test potential BBB involvement, we generated an iPSC-based BBB model of MCT8 deficiency, and we found that MCT8 was necessary for polarized influx of the active form of TH across the BBB. We also found that a candidate drug did not appreciably cross the mutant BBB. Our results therefore clarify the underlying physiological basis of this disorder, and they suggest that circumventing the diseased BBB to deliver active TH to the brain could be a viable therapeutic strategy. Copyright © 2017 Elsevier Inc. All rights reserved.

A stable and reproducible human blood-brain barrier model derived from hematopoietic stem cells.

PubMed

Cecchelli, Romeo; Aday, Sezin; Sevin, Emmanuel; Almeida, Catarina; Culot, Maxime; Dehouck, Lucie; Coisne, Caroline; Engelhardt, Britta; Dehouck, Marie-Pierre; Ferreira, Lino

2014-01-01

The human blood brain barrier (BBB) is a selective barrier formed by human brain endothelial cells (hBECs), which is important to ensure adequate neuronal function and protect the central nervous system (CNS) from disease. The development of human in vitro BBB models is thus of utmost importance for drug discovery programs related to CNS diseases. Here, we describe a method to generate a human BBB model using cord blood-derived hematopoietic stem cells. The cells were initially differentiated into ECs followed by the induction of BBB properties by co-culture with pericytes. The brain-like endothelial cells (BLECs) express tight junctions and transporters typically observed in brain endothelium and maintain expression of most in vivo BBB properties for at least 20 days. The model is very reproducible since it can be generated from stem cells isolated from different donors and in different laboratories, and could be used to predict CNS distribution of compounds in human. Finally, we provide evidence that Wnt/β-catenin signaling pathway mediates in part the BBB inductive properties of pericytes.

Angiopoietin-2 mediates blood-brain barrier impairment and colonization of triple-negative breast cancer cells in brain.

PubMed

Avraham, Hava Karsenty; Jiang, Shuxian; Fu, Yigong; Nakshatri, Harikrishna; Ovadia, Haim; Avraham, Shalom

2014-02-01

Although the incidence of breast cancer metastasis (BCM) in brain has increased significantly in triple-negative breast cancer (TNBC), the mechanisms remain elusive. Using in vivo mouse models for BCM in brain, we observed that TNBC cells crossed the blood-brain barrier (BBB), lodged in the brain microvasculature and remained adjacent to brain microvascular endothelial cells (BMECs). Breaching of the BBB in vivo by TNBCs resulted in increased BBB permeability and changes in ZO-1 and claudin-5 tight junction (TJ) protein structures. Angiopoietin-2 expression was elevated in BMECs and was correlated with BBB disruption. Secreted Ang-2 impaired TJ structures and increased BBB permeability. Treatment of mice with the neutralizing Ang-2 peptibody trebananib prevented changes in the BBB integrity and BMEC destabilization, resulting in inhibition of TNBC colonization in brain. Thus, Ang-2 is involved in initial steps of brain metastasis cascade, and inhibitors for Ang-2 may serve as potential therapeutics for brain metastasis. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Establishment of a simplified in vitro porcine blood–brain barrier model with high transendothelial electrical resistance

PubMed Central

Patabendige, Adjanie; Skinner, Robert A.; Abbott, N. Joan

2013-01-01

Good in vitro blood–brain barrier (BBB) models that mimic the in vivo BBB phenotype are essential for studies on BBB functionality and for initial screening in drug discovery programmes, as many potential therapeutic drug candidates have poor BBB permeation. Difficulties associated with the availability of human brain tissue, coupled with the time and cost associated with using animals for this kind of research have led to the development of non-human cell culture models. However, most BBB models display a low transendothelial electrical resistance (TEER), which is a measure of the tightness of the BBB. To address these issues we have established and optimised a robust, simple to use in vitro BBB model using porcine brain endothelial cells (PBECs). The PBEC model gives high TEER without the need for co-culture with astrocytes (up to 1300 Ω cm2 with a mean TEER of ∼800 Ω cm2) with well organised tight junctions as shown by immunostaining for occludin and claudin-5. Functional assays confirmed the presence of high levels of alkaline phosphatase (ALP), and presence of the efflux transporter, P-glycoprotein (P-gp, ABCB1). Presence of the breast cancer resistance protein (BCRP, ABCG2) was confirmed by TaqMan real-time RT-PCR assay. Real-time RT-PCR assays for BCRP, occludin and claudin-5 demonstrated no significant differences between batches of PBECs, and also between primary and passage 1 PBECs. A permeability screen of 10 compounds demonstrated the usefulness of the model as a tool for drug permeability studies. Qualitative and quantitative results from this study confirm that this in vitro porcine BBB model is reliable and robust; it is also simpler to generate than most other BBB models. This article is part of a Special Issue entitled Electrical Synapses. PMID:22789905

Normobaric Hyperoxia Reduces Blood Occludin Fragments in Rats and Patients With Acute Ischemic Stroke.

PubMed

Shi, Shuhai; Qi, Zhifeng; Ma, Qingfeng; Pan, Rong; Timmins, Graham S; Zhao, Yongmei; Shi, Wenjuan; Zhang, Yunzhou; Ji, Xunming; Liu, Ke Jian

2017-10-01

Damage of the blood-brain barrier (BBB) increases the incidence of neurovascular complications, especially for cerebral hemorrhage after tPA (tissue-type plasminogen activator) therapy. Currently, there is no effective method to evaluate the extent of BBB damage to guide tPA use. Herein, we investigated whether blood levels of tight junction proteins could serve as biomarker of BBB damages in acute ischemic stroke (AIS) in both rats and patients. We examined whether this biomarker could reflect the extent of BBB permeability during cerebral ischemia/reperfusion and the effects of normobaric hyperoxia (NBO) on BBB damage. Rats were exposed to NBO (100% O 2 ) or normoxia (21% O 2 ) during middle cerebral artery occlusion. BBB permeability was determined. Occludin and claudin-5 in blood and cerebromicrovessels were measured. Patients with AIS were assigned to oxygen therapy or room air for 4 hours, and blood occludin and claudin-5 were measured at different time points after stroke. Cerebral ischemia/reperfusion resulted in the degradation of occludin and claudin-5 in microvessels, leading to increased BBB permeability in rats. In blood samples, occludin increased with 4-hour ischemia and remained elevated during reperfusion, correlating well with its loss from ischemic cerebral microvessels. NBO treatment both prevented occludin degradation in microvessels and reduced occludin levels in blood, leading to improved neurological functions in rats. In patients with AIS receiving intravenous tPA thrombolysis, the blood occludin was already elevated when patients arrived at hospital (within 4.5 hours since symptoms appeared) and remained at a high level for 72 hours. NBO significantly lowered the level of blood occludin and improved neurological functions in patients with AIS. Blood occludin may be a clinically viable biomarker for evaluating BBB damage during ischemia/reperfusion. NBO therapy has the potential to reduce blood occludin, protect BBB, and improve outcome in AIS patients with intravenous tPA thrombolysis. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02974283. © 2017 American Heart Association, Inc.

Predict drug permeability to blood–brain-barrier from clinical phenotypes: drug side effects and drug indications

PubMed Central

Gao, Zhen; Chen, Yang; Cai, Xiaoshu; Xu, Rong

2017-01-01

Abstract Motivation: Blood–Brain-Barrier (BBB) is a rigorous permeability barrier for maintaining homeostasis of Central Nervous System (CNS). Determination of compound’s permeability to BBB is prerequisite in CNS drug discovery. Existing computational methods usually predict drug BBB permeability from chemical structure and they generally apply to small compounds passing BBB through passive diffusion. As abundant information on drug side effects and indications has been recorded over time through extensive clinical usage, we aim to explore BBB permeability prediction from a new angle and introduce a novel approach to predict BBB permeability from drug clinical phenotypes (drug side effects and drug indications). This method can apply to both small compounds and macro-molecules penetrating BBB through various mechanisms besides passive diffusion. Results: We composed a training dataset of 213 drugs with known brain and blood steady-state concentrations ratio and extracted their side effects and indications as features. Next, we trained SVM models with polynomial kernel and obtained accuracy of 76.0%, AUC 0.739, and F1 score (macro weighted) 0.760 with Monte Carlo cross validation. The independent test accuracy was 68.3%, AUC 0.692, F1 score 0.676. When both chemical features and clinical phenotypes were available, combining the two types of features achieved significantly better performance than chemical feature based approach (accuracy 85.5% versus 72.9%, AUC 0.854 versus 0.733, F1 score 0.854 versus 0.725; P < e−90). We also conducted de novo prediction and identified 110 drugs in SIDER database having the potential to penetrate BBB, which could serve as start point for CNS drug repositioning research. Availability and Implementation: https://github.com/bioinformatics-gao/CASE-BBB-prediction-Data Contact: rxx@case.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27993785

[The blood-brain barrier in ageing persons].

PubMed

Haaning, Nina; Damsgaard, Else Marie; Moos, Torben

2018-03-26

Brain capillary endothelial cells (BECs) form the ultra-tight blood-brain barrier (BBB). The permeability of the BBB increases with increasing age and neurovascular and neurodegenerative diseases. Major defects of the BBB can be initiated by increased permeability to plasma proteins in small arteriosclerotic arteries and release of proteins from degenerating neurons into the brain extracellular space. These proteins deposit in perivascular spaces, and subsequently negatively influence the BECs leading to decreased expression of barrier proteins. Detection of BBB defects by the use of non-invasive techniques is relevant for clinical use in settings with advanced age and severe brain disorders.

Dabigatran Etexilate Reduces Thrombin-Induced Inflammation and Thrombus Formation in Experimental Ischemic Stroke.

PubMed

Dittmeier, Melanie; Wassmuth, Kathrin; Schuhmann, Michael K; Kraft, Peter; Kleinschnitz, Christoph; Fluri, Felix

2016-01-01

Dabigatran etexilate (DE), a direct-acting, oral inhibitor of thrombin, significantly reduces the risk of stroke compared with traditional anticoagulants, without increasing the risk of major bleeding. However, studies on the fate of cerebral tissue after ischemic stroke in patients receiving DE are sparse and the role of dabigatran-mediated reduction of thrombin in this context has not yet been investigated. Here, we investigated whether pretreatment with DE reduces thrombin-mediated pro-inflammatory mechanisms and leakage of the blood-brain barrier (BBB) following ischemic stroke in rats. Male Wistar rats received DE (15 mg/kg) or a vehicle solution 1 hour before transient middle cerebral artery occlusion (tMCAO) for 90 minutes. Infarct volume, neurologic outcome and intracranial hemorrhage (ICH) were determined after tMCAO. Thrombin generation was indirectly assessed by measuring thrombin/antithrombin III complex. Microvascular patency was evaluated histologically. Cytokine expression and immunoreactivity of cluster of differentiation (CD) 68 were examined to characterize inflammatory processes after pretreatment with DE. BBB integrity was examined by quantifying brain edema. Rats given DE revealed a significant reduction in infarct size without an increase in ICH and significant recovery of neurologic deficits compared to controls. Administration of DE decreased thrombin generation and thrombus formation, dampened the CD68-immunoreactivity and attenuated pro-inflammatory cytokine expression in the cerebral parenchyma ipsilateral to the ischemic lesion. BBB permeability was unaltered following treatment with DE. In summary, prophylactic anticoagulation with DE improves stroke outcome by reducing thrombin-induced inflammation and thrombus formation without increasing the rate of ICH.

Objective measures of motor dysfunction after compression spinal cord injury in adult rats: correlations with locomotor rating scores.

PubMed

Semler, Joerg; Wellmann, Katharina; Wirth, Felicitas; Stein, Gregor; Angelova, Srebrina; Ashrafi, Mahak; Schempf, Greta; Ankerne, Janina; Ozsoy, Ozlem; Ozsoy, Umut; Schönau, Eckhard; Angelov, Doychin N; Irintchev, Andrey

2011-07-01

Precise assessment of motor deficits after traumatic spinal cord injury (SCI) in rodents is crucial for understanding the mechanisms of functional recovery and testing therapeutic approaches. Here we analyzed the applicability to a rat SCI model of an objective approach, the single-frame motion analysis, created and used for functional analysis in mice. Adult female Wistar rats were subjected to graded compression of the spinal cord. Recovery of locomotion was analyzed using video recordings of beam walking and inclined ladder climbing. Three out of four parameters used in mice appeared suitable: the foot-stepping angle (FSA) and the rump-height index (RHI), measured during beam walking, and for estimating paw placement and body weight support, respectively, and the number of correct ladder steps (CLS), assessing skilled limb movements. These parameters, similar to the Basso, Beattie, and Bresnahan (BBB) locomotor rating scores, correlated with lesion volume and showed significant differences between moderately and severely injured rats at 1-9 weeks after SCI. The beam parameters, but not CLS, correlated well with the BBB scores within ranges of poor and good locomotor abilities. FSA co-varied with RHI only in the severely impaired rats, while RHI and CLS were barely correlated. Our findings suggest that the numerical parameters estimate, as intended by design, predominantly different aspects of locomotion. The use of these objective measures combined with BBB rating provides a time- and cost-efficient opportunity for versatile and reliable functional evaluations in both severely and moderately impaired rats, combining clinical assessment with precise numerical measures.

Temporary disruption of the blood-brain barrier by use of ultrasound and microbubbles: safety and efficacy evaluation in rhesus macaques.

PubMed

McDannold, Nathan; Arvanitis, Costas D; Vykhodtseva, Natalia; Livingstone, Margaret S

2012-07-15

The blood-brain barrier (BBB) prevents entry of most drugs into the brain and is a major hurdle to the use of drugs for brain tumors and other central nervous system disorders. Work in small animals has shown that ultrasound combined with an intravenously circulating microbubble agent can temporarily permeabilize the BBB. Here, we evaluated whether this targeted drug delivery method can be applied safely, reliably, and in a controlled manner on rhesus macaques using a focused ultrasound system. We identified a clear safety window during which BBB disruption could be produced without evident tissue damage, and the acoustic pressure amplitude where the probability for BBB disruption was 50% and was found to be half of the value that would produce tissue damage. Acoustic emission measurements seem promising for predicting BBB disruption and damage. In addition, we conducted repeated BBB disruption to central visual field targets over several weeks in animals trained to conduct complex visual acuity tasks. All animals recovered from each session without behavioral deficits, visual deficits, or loss in visual acuity. Together, our findings show that BBB disruption can be reliably and repeatedly produced without evident histologic or functional damage in a clinically relevant animal model using a clinical device. These results therefore support clinical testing of this noninvasive-targeted drug delivery method.

Endothelial β-Catenin Signaling Is Required for Maintaining Adult Blood-Brain Barrier Integrity and Central Nervous System Homeostasis.

PubMed

Tran, Khiem A; Zhang, Xianming; Predescu, Dan; Huang, Xiaojia; Machado, Roberto F; Göthert, Joachim R; Malik, Asrar B; Valyi-Nagy, Tibor; Zhao, You-Yang

2016-01-12

The blood-brain barrier (BBB) formed by brain endothelial cells interconnected by tight junctions is essential for the homeostasis of the central nervous system. Although studies have shown the importance of various signaling molecules in BBB formation during development, little is known about the molecular basis regulating the integrity of the adult BBB. Using a mouse model with tamoxifen-inducible endothelial cell-restricted disruption of ctnnb1 (iCKO), we show here that endothelial β-catenin signaling is essential for maintaining BBB integrity and central nervous system homeostasis in adult mice. The iCKO mice developed severe seizures accompanied by neuronal injury, multiple brain petechial hemorrhages, and central nervous system inflammation, and all had postictal death. Disruption of endothelial β-catenin induced BBB breakdown and downregulation of the specific tight junction proteins claudin-1 and -3 in adult brain endothelial cells. The clinical relevance of the data is indicated by the observation of decreased expression of claudin-1 and nuclear β-catenin in brain endothelial cells of hemorrhagic lesions of hemorrhagic stroke patients. These results demonstrate the prerequisite role of endothelial β-catenin in maintaining the integrity of adult BBB. The results suggest that BBB dysfunction secondary to defective β-catenin transcription activity is a key pathogenic factor in hemorrhagic stroke, seizure activity, and central nervous system inflammation. © 2015 American Heart Association, Inc.

Astrocytic modulation of blood brain barrier: perspectives on Parkinson’s disease

PubMed Central

Cabezas, Ricardo; Ávila, Marcos; Gonzalez, Janneth; El-Bachá, Ramon Santos; Báez, Eliana; García-Segura, Luis Miguel; Jurado Coronel, Juan Camilo; Capani, Francisco; Cardona-Gomez, Gloria Patricia; Barreto, George E.

2014-01-01

The blood–brain barrier (BBB) is a tightly regulated interface in the Central Nervous System (CNS) that regulates the exchange of molecules in and out from the brain thus maintaining the CNS homeostasis. It is mainly composed of endothelial cells (ECs), pericytes and astrocytes that create a neurovascular unit (NVU) with the adjacent neurons. Astrocytes are essential for the formation and maintenance of the BBB by providing secreted factors that lead to the adequate association between the cells of the BBB and the formation of strong tight junctions. Under neurological disorders, such as chronic cerebral ischemia, brain trauma, Epilepsy, Alzheimer and Parkinson’s Diseases, a disruption of the BBB takes place, involving a lost in the permeability of the barrier and phenotypical changes in both the ECs and astrocytes. In this aspect, it has been established that the process of reactive gliosis is a common feature of astrocytes during BBB disruption, which has a detrimental effect on the barrier function and a subsequent damage in neuronal survival. In this review we discuss the implications of astrocyte functions in the protection of the BBB, and in the development of Parkinson’s disease (PD) and related disorders. Additionally, we highlight the current and future strategies in astrocyte protection aimed at the development of restorative therapies for the BBB in pathological conditions. PMID:25136294

Advances in Targeted Drug Delivery Approaches for the Central Nervous System Tumors: The Inspiration of Nanobiotechnology.

PubMed

Meng, Jianing; Agrahari, Vivek; Youm, Ibrahima

2017-03-01

At present, brain tumor is among the most challenging diseases to treat and the therapy is limited by the lack of effective methods to deliver anticancer agents across the blood-brain barrier (BBB). BBB is a selective barrier that separates the circulating blood from the brain extracellular fluid. In its neuroprotective function, BBB prevents the entry of toxins, as well as most of anticancer agents and is the main impediment for brain targeted drug delivery approaches. Nanotechnology-based delivery systems provide an attractive strategy to cross the BBB and reach the central nervous system (CNS). The incorporation of anticancer agents in various nanovehicles facilitates their delivery across the BBB. Moreover, a more powerful tool in brain tumor therapy has relied surface modifications of nanovehicles with specific ligands that can promote their passage through the BBB and favor the accumulation of the drug in CNS tumors. This review describes the physiological and anatomical features of the brain tumor and the BBB, and summarizes the recent advanced approaches to deliver anticancer drugs into brain tumor using nanobiotechnology-based drug carrier systems. The role of specific ligands in the design of functionalized nanovehicles for targeted delivery to brain tumor is reviewed. The current trends and future approaches in the CNS delivery of therapeutic molecules to tumors are also discussed.

Photoacoustic imaging for transvascular drug delivery to the rat brain

NASA Astrophysics Data System (ADS)

Watanabe, Ryota; Sato, Shunichi; Tsunoi, Yasuyuki; Kawauchi, Satoko; Takemura, Toshiya; Terakawa, Mitsuhiro

2015-03-01

Transvascular drug delivery to the brain is difficult due to the blood-brain barrier (BBB). Thus, various methods for safely opening the BBB have been investigated, for which real-time imaging methods are desired both for the blood vessels and distribution of a drug. Photoacoustic (PA) imaging, which enables depth-resolved visualization of chromophores in tissue, would be useful for this purpose. In this study, we performed in vivo PA imaging of the blood vessels and distribution of a drug in the rat brain by using an originally developed compact PA imaging system with fiber-based illumination. As a test drug, Evans blue (EB) was injected to the tail vein, and a photomechanical wave was applied to the targeted brain tissue to increase the permeability of the blood vessel walls. For PA imaging of blood vessels and EB distribution, nanosecond pulses at 532 nm and 670 nm were used, respectively. We clearly visualized blood vessels with diameters larger than 50 μm and the distribution of EB in the brain, showing spatiotemporal characteristics of EB that was transvascularly delivered to the target tissue in the brain.

Brain Invasion by Mouse Hepatitis Virus Depends on Impairment of Tight Junctions and Beta Interferon Production in Brain Microvascular Endothelial Cells

PubMed Central

Bleau, Christian; Filliol, Aveline; Samson, Michel

2015-01-01

ABSTRACT Coronaviruses (CoVs) have shown neuroinvasive properties in humans and animals secondary to replication in peripheral organs, but the mechanism of neuroinvasion is unknown. The major aim of our work was to evaluate the ability of CoVs to enter the central nervous system (CNS) through the blood-brain barrier (BBB). Using the highly hepatotropic mouse hepatitis virus type 3 (MHV3), its attenuated variant, 51.6-MHV3, which shows low tropism for endothelial cells, and the weakly hepatotropic MHV-A59 strain from the murine coronavirus group, we investigated the virus-induced dysfunctions of BBB in vivo and in brain microvascular endothelial cells (BMECs) in vitro. We report here a MHV strain-specific ability to cross the BBB during acute infection according to their virulence for liver. Brain invasion was observed only in MHV3-infected mice and correlated with enhanced BBB permeability associated with decreased expression of zona occludens protein 1 (ZO-1), VE-cadherin, and occludin, but not claudin-5, in the brain or in cultured BMECs. BBB breakdown in MHV3 infection was not related to production of barrier-dysregulating inflammatory cytokines or chemokines by infected BMECs but rather to a downregulation of barrier protective beta interferon (IFN-β) production. Our findings highlight the importance of IFN-β production by infected BMECs in preserving BBB function and preventing access of blood-borne infectious viruses to the brain. IMPORTANCE Coronaviruses (CoVs) infect several mammals, including humans, and are associated with respiratory, gastrointestinal, and/or neurological diseases. There is some evidence that suggest that human respiratory CoVs may show neuroinvasive properties. Indeed, the severe acute respiratory syndrome coronavirus (SARS-CoV), causing severe acute respiratory syndrome, and the CoVs OC43 and 229E were found in the brains of SARS patients and multiple sclerosis patients, respectively. These findings suggest that hematogenously spread CoVs may gain access to the CNS at the BBB level. Herein we report for the first time that CoVs exhibit the ability to cross the BBB according to strain virulence. BBB invasion by CoVs correlates with virus-induced disruption of tight junctions on BMECs, leading to BBB dysfunction and enhanced permeability. We provide evidence that production of IFN-β by BMECs during CoV infection may prevent BBB breakdown and brain viral invasion. PMID:26202229

Brain Invasion by Mouse Hepatitis Virus Depends on Impairment of Tight Junctions and Beta Interferon Production in Brain Microvascular Endothelial Cells.

PubMed

Bleau, Christian; Filliol, Aveline; Samson, Michel; Lamontagne, Lucie

2015-10-01

Coronaviruses (CoVs) have shown neuroinvasive properties in humans and animals secondary to replication in peripheral organs, but the mechanism of neuroinvasion is unknown. The major aim of our work was to evaluate the ability of CoVs to enter the central nervous system (CNS) through the blood-brain barrier (BBB). Using the highly hepatotropic mouse hepatitis virus type 3 (MHV3), its attenuated variant, 51.6-MHV3, which shows low tropism for endothelial cells, and the weakly hepatotropic MHV-A59 strain from the murine coronavirus group, we investigated the virus-induced dysfunctions of BBB in vivo and in brain microvascular endothelial cells (BMECs) in vitro. We report here a MHV strain-specific ability to cross the BBB during acute infection according to their virulence for liver. Brain invasion was observed only in MHV3-infected mice and correlated with enhanced BBB permeability associated with decreased expression of zona occludens protein 1 (ZO-1), VE-cadherin, and occludin, but not claudin-5, in the brain or in cultured BMECs. BBB breakdown in MHV3 infection was not related to production of barrier-dysregulating inflammatory cytokines or chemokines by infected BMECs but rather to a downregulation of barrier protective beta interferon (IFN-β) production. Our findings highlight the importance of IFN-β production by infected BMECs in preserving BBB function and preventing access of blood-borne infectious viruses to the brain. Coronaviruses (CoVs) infect several mammals, including humans, and are associated with respiratory, gastrointestinal, and/or neurological diseases. There is some evidence that suggest that human respiratory CoVs may show neuroinvasive properties. Indeed, the severe acute respiratory syndrome coronavirus (SARS-CoV), causing severe acute respiratory syndrome, and the CoVs OC43 and 229E were found in the brains of SARS patients and multiple sclerosis patients, respectively. These findings suggest that hematogenously spread CoVs may gain access to the CNS at the BBB level. Herein we report for the first time that CoVs exhibit the ability to cross the BBB according to strain virulence. BBB invasion by CoVs correlates with virus-induced disruption of tight junctions on BMECs, leading to BBB dysfunction and enhanced permeability. We provide evidence that production of IFN-β by BMECs during CoV infection may prevent BBB breakdown and brain viral invasion. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Functional redundancy of ventral spinal locomotor pathways.

PubMed

Loy, David N; Magnuson, David S K; Zhang, Y Ping; Onifer, Stephen M; Mills, Michael D; Cao, Qi-lin; Darnall, Jessica B; Fajardo, Lily C; Burke, Darlene A; Whittemore, Scott R

2002-01-01

Identification of long tracts responsible for the initiation of spontaneous locomotion is critical for spinal cord injury (SCI) repair strategies. Pathways derived from the mesencephalic locomotor region and pontomedullary medial reticular formation responsible for fictive locomotion in decerebrate preparations project to the thoracolumbar levels of the spinal cord via reticulospinal axons in the ventrolateral funiculus (VLF). However, white matter regions critical for spontaneous over-ground locomotion remain unclear because cats, monkeys, and humans display varying degrees of locomotor recovery after ventral SCIs. We studied the contributions of myelinated tracts in the VLF and ventral columns (VC) to spontaneous over-ground locomotion in the adult rat using demyelinating lesions. Animals received ethidium bromide plus photon irradiation producing discrete demyelinating lesions sufficient to stop axonal conduction in the VLF, VC, VLF-VC, or complete ventral white matter (CV). Behavior [open-field Basso, Beattie, and Bresnahan (BBB) scores and grid walking] and transcranial magnetic motor-evoked potentials (tcMMEP) were studied at 1, 2, and 4 weeks after lesion. VLF lesions resulted in complete loss or severe attenuation of tcMMEPs, with mean BBB scores of 18.0, and no grid walking deficits. VC lesions produced behavior similar to VLF-lesioned animals but did not significantly affect tcMMEPs. VC-VLF and CV lesions resulted in complete loss of tcMMEP signals with mean BBB scores of 12.7 and 6.5, respectively. Our data support a diffuse arrangement of axons within the ventral white matter that may comprise a system of multiple descending pathways subserving spontaneous over-ground locomotion in the intact animal.

A method to predict different mechanisms for blood-brain barrier permeability of CNS activity compounds in Chinese herbs using support vector machine.

PubMed

Jiang, Ludi; Chen, Jiahua; He, Yusu; Zhang, Yanling; Li, Gongyu

2016-02-01

The blood-brain barrier (BBB), a highly selective barrier between central nervous system (CNS) and the blood stream, restricts and regulates the penetration of compounds from the blood into the brain. Drugs that affect the CNS interact with the BBB prior to their target site, so the prediction research on BBB permeability is a fundamental and significant research direction in neuropharmacology. In this study, we combed through the available data and then with the help of support vector machine (SVM), we established an experiment process for discovering potential CNS compounds and investigating the mechanisms of BBB permeability of them to advance the research in this field four types of prediction models, referring to CNS activity, BBB permeability, passive diffusion and efflux transport, were obtained in the experiment process. The first two models were used to discover compounds which may have CNS activity and also cross the BBB at the same time; the latter two were used to elucidate the mechanism of BBB permeability of those compounds. Three optimization parameter methods, Grid Search, Genetic Algorithm (GA), and Particle Swarm Optimization (PSO), were used to optimize the SVM models. Then, four optimal models were selected with excellent evaluation indexes (the accuracy, sensitivity and specificity of each model were all above 85%). Furthermore, discrimination models were utilized to study the BBB properties of the known CNS activity compounds in Chinese herbs and this may guide the CNS drug development. With the relatively systematic and quick approach, the application rationality of traditional Chinese medicines for treating nervous system disease in the clinical practice will be improved.

Blood-brain barrier drug delivery of IgG fusion proteins with a transferrin receptor monoclonal antibody.

PubMed

Pardridge, William M

2015-02-01

Biologic drugs are large molecules that do not cross the blood- brain barrier (BBB). Brain penetration is possible following the re-engineering of the biologic drug as an IgG fusion protein. The IgG domain is a MAb against an endogenous BBB receptor such as the transferrin receptor (TfR). The TfRMAb acts as a molecular Trojan horse to ferry the fused biologic drug into the brain via receptor-mediated transport on the endogenous BBB TfR. This review discusses TfR isoforms, models of BBB transport of transferrin and TfRMAbs, and the genetic engineering of TfRMAb fusion proteins, including BBB penetrating IgG-neurotrophins, IgG-decoy receptors, IgG-lysosomal enzyme therapeutics and IgG-avidin fusion proteins, as well as BBB transport of bispecific antibodies formed by fusion of a therapeutic antibody to a TfRMAb targeting antibody. Also discussed are quantitative aspects of the plasma pharmacokinetics and brain uptake of TfRMAb fusion proteins, as compared to the brain uptake of small molecules, and therapeutic applications of TfRMAb fusion proteins in mouse models of neural disease, including Parkinson's disease, stroke, Alzheimer's disease and lysosomal storage disorders. The review covers the engineering of TfRMAb-avidin fusion proteins for BBB targeted delivery of biotinylated peptide radiopharmaceuticals, low-affinity TfRMAb Trojan horses and the safety pharmacology of chronic administration of TfRMAb fusion proteins. The BBB delivery of biologic drugs is possible following re-engineering as a fusion protein with a molecular Trojan horse such as a TfRMAb. The efficacy of this technology will be determined by the outcome of future clinical trials.

Adaptation of the Basso-Beattie-Bresnahan locomotor rating scale for use in a clinical model of spinal cord injury in dogs.

PubMed

Song, Rachel B; Basso, D Michele; da Costa, Ronaldo C; Fisher, Lesley C; Mo, Xiaokui; Moore, Sarah A

2016-08-01

Naturally occurring acute spinal cord injury (SCI) in pet dogs provides an important clinical animal model through which to confirm and extend findings from rodent studies; however, validated quantitative outcome measures for dogs are limited. We adapted the Basso Beattie Bresnahan (BBB) scale for use in a clinical dog model of acute thoracolumbar SCI. Based on observation of normal dogs, modifications were made to account for species differences in locomotion. Assessments of paw and tail position, and trunk stability were modified to produce a 19 point scale suitable for use in dogs, termed the canine BBB scale (cBBB). Pet dogs with naturally occurring acute SCI were assigned cBBB scores at 3, 10 and 30days after laminectomy. Scores assigned via the cBBB were stable across testing sessions in normal dogs but increased significantly between days 3 and 30 in SCI-affected dogs (p=0.0003). The scale was highly responsive to changes in locomotor recovery over a 30day period, with a standardized response mean of 1.34. Concurrent validity was good, with strong correlations observed between the cBBB and two other locomotor scales, the OSCIS (r=0.94; p<0.001) and the MFS (r=0.85; p<0.0001). cBBB scores inversely correlated with other assessments of recovery including mechanical sensory threshold (r=-0.68; p<0.0001) and coefficient of variation of stride length (r=-0.49; p<0.0001). These results support the use of the cBBB to assess locomotor recovery in canine clinical translational models of SCI. Copyright © 2016 Elsevier B.V. All rights reserved.

Blood-brain barrier transport machineries and targeted therapy of brain diseases

PubMed Central

Barar, Jaleh; Rafi, Mohammad A.; Pourseif, Mohammad M.; Omidi, Yadollah

2016-01-01

Introduction: Desired clinical outcome of pharmacotherapy of brain diseases largely depends upon the safe drug delivery into the brain parenchyma. However, due to the robust blockade function of the blood-brain barrier (BBB), drug transport into the brain is selectively controlled by the BBB formed by brain capillary endothelial cells and supported by astrocytes and pericytes. Methods: In the current study, we have reviewed the most recent literature on the subject to provide an insight upon the role and impacts of BBB on brain drug delivery and targeting. Results: All drugs, either small molecules or macromolecules, designated to treat brain diseases must adequately cross the BBB to provide their therapeutic properties on biological targets within the central nervous system (CNS). However, most of these pharmaceuticals do not sufficiently penetrate into CNS, failing to meet the intended therapeutic outcomes. Most lipophilic drugs capable of penetrating BBB are prone to the efflux functionality of BBB. In contrast, all hydrophilic drugs are facing severe infiltration blockage imposed by the tight cellular junctions of the BBB. Hence, a number of strategies have been devised to improve the efficiency of brain drug delivery and targeted therapy of CNS disorders using multimodal nanosystems (NSs). Conclusions: In order to improve the therapeutic outcomes of CNS drug transfer and targeted delivery, the discriminatory permeability of BBB needs to be taken under control. The carrier-mediated transport machineries of brain capillary endothelial cells (BCECs) can be exploited for the discovery, development and delivery of small molecules into the brain. Further, the receptor-mediated transport systems can be recruited for the delivery of macromolecular biologics and multimodal NSs into the brain. PMID:28265539

Rapid transport of CCL11 across the blood-brain barrier: regional variation and importance of blood cells.

PubMed

Erickson, Michelle A; Morofuji, Yoichi; Owen, Joshua B; Banks, William A

2014-06-01

Increased blood levels of the eotaxin chemokine C-C motif ligand 11 (CCL11) in aging were recently shown to negatively regulate adult hippocampal neurogenesis. How circulating CCL11 could affect the central nervous system (CNS) is not clear, but one possibility is that it can cross the blood-brain barrier (BBB). Here, we show that CCL11 undergoes bidirectional transport across the BBB. Transport of CCL11 from blood into whole brain (influx) showed biphasic kinetics, with a slow phase preceding a rapid phase of uptake. We found that the slow phase was explained by binding of CCL11 to cellular components in blood, whereas the rapid uptake phase was mediated by direct interactions with the BBB. CCL11, even at high doses, did not cause BBB disruption. All brain regions except striatum showed a delayed rapid-uptake phase. Striatum had only an early rapid-uptake phase, which was the fastest of any brain region. We also observed a slow but saturable transport system for CCL11 from brain to blood. C-C motif ligand 3 (CCR3), an important receptor for CCL11, did not facilitate CCL11 transport across the BBB, although high concentrations of a CCR3 inhibitor increased brain uptake without causing BBB disruption. Our results indicate that CCL11 in the circulation can access many regions of the brain outside of the neurogenic niche via transport across the BBB. This suggests that blood-borne CCL11 may have important physiologic functions in the CNS and implicates the BBB as an important regulator of physiologic versus pathologic effects of this chemokine.

Rapid Transport of CCL11 across the Blood-Brain Barrier: Regional Variation and Importance of Blood Cells

PubMed Central

Erickson, Michelle A.; Morofuji, Yoichi; Owen, Joshua B.

2014-01-01

Increased blood levels of the eotaxin chemokine C-C motif ligand 11 (CCL11) in aging were recently shown to negatively regulate adult hippocampal neurogenesis. How circulating CCL11 could affect the central nervous system (CNS) is not clear, but one possibility is that it can cross the blood-brain barrier (BBB). Here, we show that CCL11 undergoes bidirectional transport across the BBB. Transport of CCL11 from blood into whole brain (influx) showed biphasic kinetics, with a slow phase preceding a rapid phase of uptake. We found that the slow phase was explained by binding of CCL11 to cellular components in blood, whereas the rapid uptake phase was mediated by direct interactions with the BBB. CCL11, even at high doses, did not cause BBB disruption. All brain regions except striatum showed a delayed rapid-uptake phase. Striatum had only an early rapid-uptake phase, which was the fastest of any brain region. We also observed a slow but saturable transport system for CCL11 from brain to blood. C-C motif ligand 3 (CCR3), an important receptor for CCL11, did not facilitate CCL11 transport across the BBB, although high concentrations of a CCR3 inhibitor increased brain uptake without causing BBB disruption. Our results indicate that CCL11 in the circulation can access many regions of the brain outside of the neurogenic niche via transport across the BBB. This suggests that blood-borne CCL11 may have important physiologic functions in the CNS and implicates the BBB as an important regulator of physiologic versus pathologic effects of this chemokine. PMID:24706984

Blood-brain barrier transport machineries and targeted therapy of brain diseases.

PubMed

Barar, Jaleh; Rafi, Mohammad A; Pourseif, Mohammad M; Omidi, Yadollah

2016-01-01

Introduction: Desired clinical outcome of pharmacotherapy of brain diseases largely depends upon the safe drug delivery into the brain parenchyma. However, due to the robust blockade function of the blood-brain barrier (BBB), drug transport into the brain is selectively controlled by the BBB formed by brain capillary endothelial cells and supported by astrocytes and pericytes. Methods: In the current study, we have reviewed the most recent literature on the subject to provide an insight upon the role and impacts of BBB on brain drug delivery and targeting. Results: All drugs, either small molecules or macromolecules, designated to treat brain diseases must adequately cross the BBB to provide their therapeutic properties on biological targets within the central nervous system (CNS). However, most of these pharmaceuticals do not sufficiently penetrate into CNS, failing to meet the intended therapeutic outcomes. Most lipophilic drugs capable of penetrating BBB are prone to the efflux functionality of BBB. In contrast, all hydrophilic drugs are facing severe infiltration blockage imposed by the tight cellular junctions of the BBB. Hence, a number of strategies have been devised to improve the efficiency of brain drug delivery and targeted therapy of CNS disorders using multimodal nanosystems (NSs). Conclusions: In order to improve the therapeutic outcomes of CNS drug transfer and targeted delivery, the discriminatory permeability of BBB needs to be taken under control. The carrier-mediated transport machineries of brain capillary endothelial cells (BCECs) can be exploited for the discovery, development and delivery of small molecules into the brain. Further, the receptor-mediated transport systems can be recruited for the delivery of macromolecular biologics and multimodal NSs into the brain.

Endothelium-targeted overexpression of heat shock protein 27 ameliorates blood–brain barrier disruption after ischemic brain injury

PubMed Central

Jiang, Xiaoyan; Zhang, Lili; Pu, Hongjian; Hu, Xiaoming; Zhang, Wenting; Cai, Wei; Gao, Yanqin; Leak, Rehana K.; Keep, Richard F.; Bennett, Michael V. L.; Chen, Jun

2017-01-01

The damage borne by the endothelial cells (ECs) forming the blood–brain barrier (BBB) during ischemic stroke and other neurological conditions disrupts the structure and function of the neurovascular unit and contributes to poor patient outcomes. We recently reported that structural aberrations in brain microvascular ECs—namely, uncontrolled actin polymerization and subsequent disassembly of junctional proteins, are a possible cause of the early onset BBB breach that arises within 30–60 min of reperfusion after transient focal ischemia. Here, we investigated the role of heat shock protein 27 (HSP27) as a direct inhibitor of actin polymerization and protectant against BBB disruption after ischemia/reperfusion (I/R). Using in vivo and in vitro models, we found that targeted overexpression of HSP27 specifically within ECs—but not within neurons—ameliorated BBB impairment 1–24 h after I/R. Mechanistically, HSP27 suppressed I/R-induced aberrant actin polymerization, stress fiber formation, and junctional protein translocation in brain microvascular ECs, independent of its protective actions against cell death. By preserving BBB integrity after I/R, EC-targeted HSP27 overexpression attenuated the infiltration of potentially destructive neutrophils and macrophages into brain parenchyma, thereby improving long-term stroke outcome. Notably, early poststroke administration of HSP27 attached to a cell-penetrating transduction domain (TAT-HSP27) rapidly elevated HSP27 levels in brain microvessels and ameliorated I/R-induced BBB disruption and subsequent neurological deficits. Thus, the present study demonstrates that HSP27 can function at the EC level to preserve BBB integrity after I/R brain injury. HSP27 may be a therapeutic agent for ischemic stroke and other neurological conditions involving BBB breakdown. PMID:28137866

Anesthesia and Surgery Impair Blood–Brain Barrier and Cognitive Function in Mice

PubMed Central

Yang, Siming; Gu, Changping; Mandeville, Emiri T.; Dong, Yuanlin; Esposito, Elga; Zhang, Yiying; Yang, Guang; Shen, Yuan; Fu, Xiaobing; Lo, Eng H.; Xie, Zhongcong

2017-01-01

Blood–brain barrier (BBB) dysfunction, e.g., increase in BBB permeability, has been reported to contribute to cognitive impairment. However, the effects of anesthesia and surgery on BBB permeability, the underlying mechanisms, and associated cognitive function remain largely to be determined. Here, we assessed the effects of surgery (laparotomy) under 1.4% isoflurane anesthesia (anesthesia/surgery) for 2 h on BBB permeability, levels of junction proteins and cognitive function in both 9- and 18-month-old wild-type mice and 9-month-old interleukin (IL)-6 knockout mice. BBB permeability was determined by dextran tracer (immunohistochemistry imaging and spectrophotometric quantification), and protein levels were measured by Western blot and cognitive function was assessed by using both Morris water maze and Barnes maze. We found that the anesthesia/surgery increased mouse BBB permeability to 10-kDa dextran, but not to 70-kDa dextran, in an IL-6-dependent and age-associated manner. In addition, the anesthesia/surgery induced an age-associated increase in blood IL-6 level. Cognitive impairment was detected in 18-month-old, but not 9-month-old, mice after the anesthesia/surgery. Finally, the anesthesia/surgery decreased the levels of β-catenin and tight junction protein claudin, occludin and ZO-1, but not adherent junction protein VE-cadherin, E-cadherin, and p120-catenin. These data demonstrate that we have established a system to study the effects of perioperative factors, including anesthesia and surgery, on BBB and cognitive function. The results suggest that the anesthesia/surgery might induce an age-associated BBB dysfunction and cognitive impairment in mice. These findings would promote mechanistic studies of postoperative cognitive impairment, including postoperative delirium. PMID:28848542

PROGRESS AND PROBLEMS IN THE APPLICATION OF FOCUSED ULTRASOUND FOR BLOOD-BRAIN BARRIER DISRUPTION

PubMed Central

Vykhodtseva, Natalia; McDannold, Nathan; Hynynen, Kullervo

2008-01-01

Advances in neuroscience have resulted in the development of new diagnostic and therapeutic agents for potential use in the central nervous system (CNS). However, the ability to deliver the majority of these agents to the brain is limited by the blood–brain barrier (BBB), a specialized structure of the blood vessel wall that hampers transport and diffusion from the blood to the brain. Many CNS disorders could be treated with drugs, enzymes, genes, or large-molecule biotechnological products such as recombinant proteins, if they could cross the BBB. This article reviews the problems of the BBB presence in treating the vast majority of CNS diseases and the efforts to circumvent the BBB through the design of new drugs and the development of more sophisticated delivery methods. Recent advances in the development of noninvasive, targeted drug delivery by MRI-guided ultrasound-induced BBB disruption are also summarized. PMID:18511095

Magnetic resonance imaging of post-ischemic blood-brain barrier damage with PEGylated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Liu, Dong-Fang; Qian, Cheng; An, Yan-Li; Chang, Di; Ju, Sheng-Hong; Teng, Gao-Jun

2014-11-01

Blood-brain barrier (BBB) damage during ischemia may induce devastating consequences like cerebral edema and hemorrhagic transformation. This study presents a novel strategy for dynamically imaging of BBB damage with PEGylated supermagnetic iron oxide nanoparticles (SPIONs) as contrast agents. The employment of SPIONs as contrast agents made it possible to dynamically image the BBB permeability alterations and ischemic lesions simultaneously with T2-weighted MRI, and the monitoring could last up to 24 h with a single administration of PEGylated SPIONs in vivo. The ability of the PEGylated SPIONs to highlight BBB damage by MRI was demonstrated by the colocalization of PEGylated SPIONs with Gd-DTPA after intravenous injection of SPION-PEG/Gd-DTPA into a mouse. The immunohistochemical staining also confirmed the leakage of SPION-PEG from cerebral vessels into parenchyma. This study provides a novel and convenient route for imaging BBB alteration in the experimental ischemic stroke model.

Blood-brain barrier hyperpermeability precedes demyelination in the cuprizone model.

PubMed

Berghoff, Stefan A; Düking, Tim; Spieth, Lena; Winchenbach, Jan; Stumpf, Sina K; Gerndt, Nina; Kusch, Kathrin; Ruhwedel, Torben; Möbius, Wiebke; Saher, Gesine

2017-12-01

In neuroinflammatory disorders such as multiple sclerosis, the physiological function of the blood-brain barrier (BBB) is perturbed, particularly in demyelinating lesions and supposedly secondary to acute demyelinating pathology. Using the toxic non-inflammatory cuprizone model of demyelination, we demonstrate, however, that the onset of persistent BBB impairment precedes demyelination. In addition to a direct effect of cuprizone on endothelial cells, a plethora of inflammatory mediators, which are mainly of astroglial origin during the initial disease phase, likely contribute to the destabilization of endothelial barrier function in vivo. Our study reveals that, at different time points of pathology and in different CNS regions, the level of gliosis correlates with the extent of BBB hyperpermeability and edema. Furthermore, in mutant mice with abolished type 3 CXC chemokine receptor (CXCR3) signaling, inflammatory responses are dampened and BBB dysfunction ameliorated. Together, these data have implications for understanding the role of BBB permeability in the pathogenesis of demyelinating disease.

Delivery of peptide and protein drugs over the blood-brain barrier.

PubMed

Brasnjevic, Ivona; Steinbusch, Harry W M; Schmitz, Christoph; Martinez-Martinez, Pilar

2009-04-01

Peptide and protein (P/P) drugs have been identified as showing great promises for the treatment of various neurodegenerative diseases. A major challenge in this regard, however, is the delivery of P/P drugs over the blood-brain barrier (BBB). Intense research over the last 25 years has enabled a better understanding of the cellular and molecular transport mechanisms at the BBB, and several strategies for enhanced P/P drug delivery over the BBB have been developed and tested in preclinical and clinical-experimental research. Among them, technology-based approaches (comprising functionalized nanocarriers and liposomes) and pharmacological strategies (such as the use of carrier systems and chimeric peptide technology) appear to be the most promising ones. This review combines a comprehensive overview on the current understanding of the transport mechanisms at the BBB with promising selected strategies published so far that can be applied to facilitate enhanced P/P drug delivery over the BBB.

Aquaporin-4 Functionality and Virchow-Robin Space Water Dynamics: Physiological Model for Neurovascular Coupling and Glymphatic Flow

PubMed Central

Kwee, Ingrid L.

2017-01-01

The unique properties of brain capillary endothelium, critical in maintaining the blood-brain barrier (BBB) and restricting water permeability across the BBB, have important consequences on fluid hydrodynamics inside the BBB hereto inadequately recognized. Recent studies indicate that the mechanisms underlying brain water dynamics are distinct from systemic tissue water dynamics. Hydrostatic pressure created by the systolic force of the heart, essential for interstitial circulation and lymphatic flow in systemic circulation, is effectively impeded from propagating into the interstitial fluid inside the BBB by the tightly sealed endothelium of brain capillaries. Instead, fluid dynamics inside the BBB is realized by aquaporin-4 (AQP-4), the water channel that connects astrocyte cytoplasm and extracellular (interstitial) fluid. Brain interstitial fluid dynamics, and therefore AQP-4, are now recognized as essential for two unique functions, namely, neurovascular coupling and glymphatic flow, the brain equivalent of systemic lymphatics. PMID:28820467

How Cryptococcus interacts with the blood-brain barrier.

PubMed

Tseng, Hsiang-Kuang; Huang, Tseng-Yu; Wu, Alice Ying-Jung; Chen, Hsin-Hong; Liu, Chang-Pan; Jong, Ambrose

2015-01-01

Cryptococcus demonstrates predilection for invasion of the brain, but the mechanism by which Cryptococcus crosses the blood-brain barrier (BBB) to cause brain invasion is largely unknown. In order for Cryptococcus to cross the BBB, there must be a way to either cross human brain microvascular endothelial cells, which are the main constitute of the BBB, or go in between tight junctions. Recent evidence of human brain microvascular endothelial cell responses to transcellular brain invasions includes membrane rearrangements, intracellular signaling pathways and cytoskeletal activations. Several Cryptococcal genes related to the traversal of BBB have been identified, including CPS1, ITR1a, ITR3c, PLB1, MPR1, FNX1 and RUB1. In addition, Cryptococcus neoformans-derived microvesicles may contribute to cryptococcal brain invasion. Paracellularly, Cryptococcus may traverse across BBB using either routes utilizing plasmin, ammonia or macrophages in a Trojan horse mechanism.

The effects of hypoglycemic and alcoholic coma on the blood-brain barrier permeability

PubMed Central

Yorulmaz, Hatice; Seker, Fatma Burcu; Oztas, Baria

2011-01-01

In this investigation, the effects of hypoglycemic coma and alcoholic coma on the blood-brain barrier (BBB) permeability have been compared. Female adult Wistar albino rats weighing 180-230 g were divided into three groups: Control group (n=8), Alcoholic Coma Group (n=18), and Hypoglycemic Coma group (n=12). The animals went into coma approximately 3-4 hours after insulin administration and 3-5 minutes after alcohol administration. Evans blue (4mL/kg) was injected intravenously as BBB tracer. It was observed that the alcoholic coma did not significantly increase the BBB permeability in any of the brain regions when compared to control group. Changes in BBB permeability were significantly increased by the hypoglycemic coma in comparison to the control group values (p<0.01). Our findings suggest that hypoglycemic and alcoholic coma have different effects on the BBB permeability depending on the energy metabolism. PMID:21619558

Aquaporin-4 Functionality and Virchow-Robin Space Water Dynamics: Physiological Model for Neurovascular Coupling and Glymphatic Flow.

PubMed

Nakada, Tsutomu; Kwee, Ingrid L; Igarashi, Hironaka; Suzuki, Yuji

2017-08-18

The unique properties of brain capillary endothelium, critical in maintaining the blood-brain barrier (BBB) and restricting water permeability across the BBB, have important consequences on fluid hydrodynamics inside the BBB hereto inadequately recognized. Recent studies indicate that the mechanisms underlying brain water dynamics are distinct from systemic tissue water dynamics. Hydrostatic pressure created by the systolic force of the heart, essential for interstitial circulation and lymphatic flow in systemic circulation, is effectively impeded from propagating into the interstitial fluid inside the BBB by the tightly sealed endothelium of brain capillaries. Instead, fluid dynamics inside the BBB is realized by aquaporin-4 (AQP-4), the water channel that connects astrocyte cytoplasm and extracellular (interstitial) fluid. Brain interstitial fluid dynamics, and therefore AQP-4, are now recognized as essential for two unique functions, namely, neurovascular coupling and glymphatic flow, the brain equivalent of systemic lymphatics.

Focal cerebral ischemic tolerance and change in blood-brain barrier permeability after repetitive pure oxygen exposure preconditioning in a rodent model.

PubMed

Wang, Xi; Kang, Kai; Wang, Shiquan; Yao, Jianhua; Zhang, Xijing

2016-10-01

OBJECTIVE The goal of this study was to demonstrate that repetitive pure oxygen exposure preconditioning (O 2 PC) for 8 hours per day for 3 or 7 days, a practicable preconditioning for clinical use, is able to induce cerebral ischemic tolerance (IT) and further clarify the accompanying changes in the blood-brain barrier (BBB) that may be involved. METHODS A total of 68 adult male Sprague-Dawley rats and eight 1-day-old rat pups were used in this study. The adult rats were exposed to pure O 2 (38 rats) 8 hours a day for 3 or 7 days or to room air (in an identical setup) for 8 hours a day for 7 days as controls (30 rats). Arterial O 2 tension (PaO 2 ) was measured in 6 rats exposed to O 2 and 3 controls. Focal cerebral ischemia was elicited by middle cerebral artery occlusion (MCAO) in 37 rats, of which 21 had been exposed to pure O 2 for 3 or 7 days and 16 to room air for 7 days as controls. Neurological behavior was scored with the Garcia score in 15 MCAO rats, of which 10 had been exposed to pure O 2 for 3 or 7 days and 5 to room air for 7 days as controls, and cerebral infarct volumes were assessed with TTC (2,3,5-triphenyltetrazolium chloride) staining in 10 rats (5 from each group) after 7 days of exposure. Formamide-extraction method was used to detect leakage of Evans blue (EB) dye in 7 rats exposed to pure O 2 for 7 days and 7 exposed to room air for 7 days. Fluorescence microscopy was used to analyze the leaked EB in the nonischemic areas of 4 rats exposed to pure O 2 for 7 days and 4 exposed to room air for 7 days before MCAO and the brain of the rats that had not been subjected to MCAO. Astrocyte changes associated with O 2 PC were evaluated by means of fluorescence microscopy and electron microscopy in 14 rats that were exposed to the same O 2 or control conditions as the MCAO rats but without MCAO. Astrocytes were also obtained from 8 rat pups and cultured; levels of AQP4 and VEGF were detected by Western blot and ELISA in cells with and without O 2 treatment. RESULTS A significant increase in PaO 2 was seen after O 2 PC. The neurological score was significantly increased in the O 2 PC groups (10.6 ± 0.6 in the 3-day O 2 PC group, p < 0.05; 12 ± 0.84 in the 7-day O 2 PC group, p < 0.05) compared with the control group (7 ± 0.55). The ratio of cerebral infarct volume to contralateral cerebral hemisphere volume was significantly lower in the O 2 PC group than in the control group (0.204 ± 0.03 vs 0.48 ± 0.05, p < 0.05). The amount of leaked EB in the ischemic cerebral hemisphere was also lower in the O 2 -treated rats than in controls (7.53 ± 1.4 vs 11.79 ± 3.3 μg EB/g brain weight, p < 0.05). However, fluorescence microscopy showed significantly greater BBB permeability in the nonischemic areas in the O 2 PC group than in controls (p < 0.05). More red fluorescence could be observed in the nonischemic areas in both the ipsilateral and contralateral sides of the ischemic brain in the O 2 PC animals than in the nonischemic areas in the corresponding sides of the controls. Further investigation of the effect of the O 2 PC itself on the BBB of rats that were not subjected to MCAO showed that there was no EB leakage in the brain parenchyma in the rats exposed to room air, but some red fluorescence patches were noticed in the normal brain from the rats in the O 2 PC group. Astrocytes, including those from areas around the BBB, were activated in the O 2 PC group. Levels of both aquaporin 4 (AQP4) and vascular endothelial growth factor (VEGF) were significantly increased in cultured astrocytes after O 2 PC. CONCLUSIONS These findings suggest that O 2 PC is able to induce IT, which makes it a strong candidate for clinical use. Moreover, O 2 PC can also promote BBB opening, which may contribute to the induction of IT as well as representing a possible strategy for promoting drug transportation into the CNS. Activated astrocytes are likely to be involved in these processes through astrocyte-derived factors, such as AQP4 and VEGF.

12 CFR Appendix B to Subpart A of... - Appendix B to Subpart A of Part 327

Code of Federal Regulations, 2010 CFR

2010-01-01

... Converted value Standard & Poor's: AAA 1.00 AA+ 1.05 AA 1.15 AA− 1.30 A+ 1.50 A 1.80 A− 2.20 BBB+ 2.70 BBB or worse 3.00 Moody's: Aaa 1.00 Aa1 1.05 Aa2 1.15 Aa3 1.30 A1 1.50 A2 1.80 A3 2.20 Baa1 2.70 Baa2 or worse 3.00 Fitch's: AAA 1.00 AA+ 1.05 AA 1.15 AA− 1.30 A+ 1.50 A 1.80 A− 2.20 BBB+ 2.70 BBB or worse 3...

Impairment of blood-brain barrier is an early event in R6/2 mouse model of Huntington Disease.

PubMed

Di Pardo, Alba; Amico, Enrico; Scalabrì, Francesco; Pepe, Giuseppe; Castaldo, Salvatore; Elifani, Francesca; Capocci, Luca; De Sanctis, Claudia; Comerci, Laura; Pompeo, Francesco; D'Esposito, Maurizio; Filosa, Stefania; Crispi, Stefania; Maglione, Vittorio

2017-01-24

Blood-brain barrier (BBB) breakdown, due to the concomitant disruption of the tight junctions (TJs), normally required for the maintenance of BBB function, and to the altered transport of molecules between blood and brain and vice-versa, has been suggested to significantly contribute to the development and progression of different brain disorders including Huntington's disease (HD). Although the detrimental consequence the BBB breakdown may have in the clinical settings, the timing of its alteration remains elusive for many neurodegenerative diseases. In this study we demonstrate for the first time that BBB disruption in HD is not confined to established symptoms, but occurs early in the disease progression. Despite the obvious signs of impaired BBB permeability were only detectable in concomitance with the onset of the disease, signs of deranged TJs integrity occur precociously in the disease and precede the onset of overt symptoms. To our perspective this finding may add a new dimension to the horizons of pathological mechanisms underlying this devastating disease, however much remains to be elucidated for understanding how specific BBB drug targets can be approached in the future.

CNS angiogenesis and barriergenesis occur simultaneously.

PubMed

Umans, Robyn A; Henson, Hannah E; Mu, Fangzhou; Parupalli, Chaithanyarani; Ju, Bensheng; Peters, Jennifer L; Lanham, Kevin A; Plavicki, Jessica S; Taylor, Michael R

2017-05-15

The blood-brain barrier (BBB) plays a vital role in the central nervous system (CNS). A comprehensive understanding of BBB development has been hampered by difficulties in observing the differentiation of brain endothelial cells (BECs) in real-time. Here, we generated two transgenic zebrafish line, Tg(glut1b:mCherry) and Tg(plvap:EGFP), to serve as in vivo reporters of BBB development. We showed that barriergenesis (i.e. the induction of BEC differentiation) occurs immediately as endothelial tips cells migrate into the brain parenchyma. Using the Tg(glut1b:mCherry) transgenic line, we performed a genetic screen and identified a zebrafish mutant with a nonsense mutation in gpr124, a gene known to play a role in CNS angiogenesis and BBB development. We also showed that our transgenic plvap:EGFP line, a reporter of immature brain endothelium, is initially expressed in newly formed brain endothelial cells, but subsides during BBB maturation. Our results demonstrate the ability to visualize the in vivo differentiation of brain endothelial cells into the BBB phenotype and establish that CNS angiogenesis and barriergenesis occur simultaneously. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Host matrix metalloproteinases in cerebral malaria: new kids on the block against blood–brain barrier integrity?

PubMed Central

2014-01-01

Cerebral malaria (CM) is a life-threatening complication of falciparum malaria, associated with high mortality rates, as well as neurological impairment in surviving patients. Despite disease severity, the etiology of CM remains elusive. Interestingly, although the Plasmodium parasite is sequestered in cerebral microvessels, it does not enter the brain parenchyma: so how does Plasmodium induce neuronal dysfunction? Several independent research groups have suggested a mechanism in which increased blood–brain barrier (BBB) permeability might allow toxic molecules from the parasite or the host to enter the brain. However, the reported severity of BBB damage in CM is variable depending on the model system, ranging from mild impairment to full BBB breakdown. Moreover, the factors responsible for increased BBB permeability are still unknown. Here we review the prevailing theories on CM pathophysiology and discuss new evidence from animal and human CM models implicating BBB damage. Finally, we will review the newly-described role of matrix metalloproteinases (MMPs) and BBB integrity. MMPs comprise a family of proteolytic enzymes involved in modulating inflammatory response, disrupting tight junctions, and degrading sub-endothelial basal lamina. As such, MMPs represent potential innovative drug targets for CM. PMID:24467887

The Metalloprotease, Mpr1, Engages AnnexinA2 to Promote the Transcytosis of Fungal Cells across the Blood-Brain Barrier

PubMed Central

Na Pombejra, Sarisa; Salemi, Michelle; Phinney, Brett S.; Gelli, Angie

2017-01-01

Eukaryotic pathogens display multiple mechanisms for breaching the blood-brain barrier (BBB) and invading the central nervous system (CNS). Of the fungal spp., that cause disease in mammals, only some cross brain microvascular endothelial cells which constitute the BBB, and invade the brain. Cryptococcus neoformans, the leading cause of fungal meningoencephalitis, crosses the BBB directly by transcytosis or by co-opting monocytes. We previously determined that Mpr1, a secreted fungal metalloprotease, facilitates association of fungal cells to brain microvascular endothelial cells and we confirmed that the sole expression of CnMPR1 endowed S. cerevisiae with an ability to cross the BBB. Here, the gain of function conferred onto S. cerevisiae by CnMPR1 (i.e., Sc strain) was used to identify targets of Mpr1 that might reside on the surface of the BBB. Following biotin-labeling of BBB surface proteins, Sc-associated proteins were identified by LC-MS/MS. Of the 62 proteins identified several were cytoskeleton-endocytosis-associated including AnnexinA2 (AnxA2). Using an in vitro model of the human BBB where AnxA2 activity was blocked, we found that the lack of AnxA2 activity prevented the movement of S. cerevisiae across the BBB (i.e., transcytosis of Sc strain) but unexpectedly, TEM analysis revealed that AnxA2 was not required for the association or the internalization of Sc. Additionally, the co-localization of AnxA2 and Sc suggest that successful crossing of the BBB is dependent on an AxnA2-Mpr1-mediated interaction. Collectively the data suggest that AnxA2 plays a central role in fungal transcytosis in human brain microvascular endothelial cells. The movement and exocytosis of Sc is dependent on membrane trafficking events that involve AnxA2 but these events appear to be independent from the actions of AnxA2 at the host cell surface. We propose that Mpr1 activity promotes cytoskeleton remodeling in brain microvascular endothelial cells and thereby engages AnxA2 in order to facilitate fungal transcytosis of the BBB. PMID:28713781

The Metalloprotease, Mpr1, Engages AnnexinA2 to Promote the Transcytosis of Fungal Cells across the Blood-Brain Barrier.

PubMed

Na Pombejra, Sarisa; Salemi, Michelle; Phinney, Brett S; Gelli, Angie

2017-01-01

Eukaryotic pathogens display multiple mechanisms for breaching the blood-brain barrier (BBB) and invading the central nervous system (CNS). Of the fungal spp., that cause disease in mammals, only some cross brain microvascular endothelial cells which constitute the BBB, and invade the brain. Cryptococcus neoformans , the leading cause of fungal meningoencephalitis, crosses the BBB directly by transcytosis or by co-opting monocytes. We previously determined that Mpr1, a secreted fungal metalloprotease, facilitates association of fungal cells to brain microvascular endothelial cells and we confirmed that the sole expression of Cn MPR1 endowed S. cerevisiae with an ability to cross the BBB. Here, the gain of function conferred onto S. cerevisiae by Cn MPR1 (i.e., Sc strain) was used to identify targets of Mpr1 that might reside on the surface of the BBB. Following biotin-labeling of BBB surface proteins, Sc-associated proteins were identified by LC-MS/MS. Of the 62 proteins identified several were cytoskeleton-endocytosis-associated including AnnexinA2 (AnxA2). Using an in vitro model of the human BBB where AnxA2 activity was blocked, we found that the lack of AnxA2 activity prevented the movement of S. cerevisiae across the BBB (i.e., transcytosis of Sc strain) but unexpectedly, TEM analysis revealed that AnxA2 was not required for the association or the internalization of Sc. Additionally, the co-localization of AnxA2 and Sc suggest that successful crossing of the BBB is dependent on an AxnA2-Mpr1-mediated interaction. Collectively the data suggest that AnxA2 plays a central role in fungal transcytosis in human brain microvascular endothelial cells. The movement and exocytosis of Sc is dependent on membrane trafficking events that involve AnxA2 but these events appear to be independent from the actions of AnxA2 at the host cell surface. We propose that Mpr1 activity promotes cytoskeleton remodeling in brain microvascular endothelial cells and thereby engages AnxA2 in order to facilitate fungal transcytosis of the BBB.

Transporters at CNS Barrier Sites: Obstacles or Opportunities for Drug Delivery?

PubMed Central

Sanchez-Covarrubias, Lucy; Slosky, Lauren M.; Thompson, Brandon J.; Davis, Thomas P.; Ronaldson, Patrick T.

2014-01-01

The blood-brain barrier (BBB) and blood-cerebrospinal fluid (BCSF) barriers are critical determinants of CNS homeostasis. Additionally, the BBB and BCSF barriers are formidable obstacles to effective CNS drug delivery. These brain barrier sites express putative influx and efflux transporters that precisely control permeation of circulating solutes including drugs. The study of transporters has enabled a shift away from “brute force” approaches to delivering drugs by physically circumventing brain barriers towards chemical approaches that can target specific compounds of the BBB and/or BCSF barrier. However, our understanding of transporters at the BBB and BCSF barriers has primarily focused on understanding efflux transporters that efficiently prevent drugs from attaining therapeutic concentrations in the CNS. Recently, through the characterization of multiple endogenously expressed uptake transporters, this paradigm has shifted to the study of brain transporter targets that can facilitate drug delivery (i.e., influx transporters). Additionally, signaling pathways and trafficking mechanisms have been identified for several endogenous BBB/BCSF transporters, thereby offering even more opportunities to understand how transporters can be exploited for optimization of CNS drug delivery. This review presents an overview of the BBB and BCSF barrier as well as the many families of transporters functionally expressed at these barrier sites. Furthermore, we present an overview of various strategies that have been designed and utilized to deliver therapeutic agents to the brain with a particular emphasis on those approaches that directly target endogenous BBB/BCSF barrier transporters. PMID:23789948

Targeted Vascular Drug Delivery in Cerebral Cancer.

PubMed

Humle, Nanna; Johnsen, Kasper Bendix; Arendt, Gitte Abildgaard; Nielsen, Rikke Paludan; Moos, Torben; Thomsen, Louiza Bohn

2016-01-01

This review presents the present-day literature on the anatomy and physiological mechanisms of the blood-brain barrier and the problematic of cerebral drug delivery in relation to malignant brain tumors. First step in treatment of malignant brain tumors is resection, but there is a high risk of single remnant infiltrative tumor cells in the outer zone of the brain tumor. These infiltrative single-cells will be supplied by capillaries with an intact BBB as opposed to the partly leaky BBB found in the tumor tissue before resection. Even though BBB penetrance of a chemotherapeutic agent is considered irrelevant though the limited success rate for chemotherapeutic treatability of GBM tumors indicate otherwise. Therefore drug delivery strategies to cerebral cancer after resection should be tailored to being able to both penetrate the intact BBB and target the cancer cells. In this review the intact bloodbrain barrier and cerebral cancer with main focus on glioblastoma multiforme (GBM) is introduced. The GBM induced formation of a blood-tumor barrier and the consequences hereof is described and discussed with emphasis on the impact these changes of the BBB has on drug delivery to GBM. The most commonly used drug carriers for drug delivery to GBM is described and the current drug delivery strategies for glioblastoma multiforme including possible routes through the BBB and epitopes, which can be targeted on the GBM cells is outlined. Overall, this review aims to address targeted drug delivery in GBM treatment when taking the differing permeability of the BBB into consideration.

Poly(ADP-ribose) polymerase-1 regulates microglia mediated decrease of endothelial tight junction integrity.

PubMed

Mehrabadi, Abbas Rezaeian; Korolainen, Minna A; Odero, Gary; Miller, Donald W; Kauppinen, Tiina M

2017-09-01

Alzheimer's disease pathology includes, beside neuronal damage, reactive gliosis and reduced blood-brain barrier (BBB) integrity. Microglia are intimately associated with the BBB and upon AD pathology, pro-inflammatory responses of microglia could contribute to BBB damage. To study whether microglia can directly affect BBB integrity, the effects of amyloid beta (Aβ) -stimulated primary murine microglia on co-cultured mouse brain endothelial cells (bEnd3) and murine astrocyte cultures were assessed. We also assessed whether microglial phenotype modulation via poly(ADP-ribose) polymerase-1 (PARP-1) inhibition/ablation can reverse microglial impact on these BBB forming cells. Unstimulated microglia promoted expression of tight junction proteins (TJPs), zonula ocluden-1 (ZO-1) and occludin in co-cultured endothelia cells, whereas Aβ-stimulated microglia reduced endothelial expression of ZO-1 and occludin. Astrocytes co-cultured with microglia showed elevated glial fibrillary acidic protein (GFAP) expression, which was further increased if microglia had been stimulated with Aβ. Aβ induced microglial release of nitric oxide (NO) and tumour necrosis factor alpha (TNFα), which resulted in reduced endothelial expression of TJPs and increased paracellular permeability. Microglial PARP-1 inhibition attenuated these Aβ-induced events. These findings demonstrate that PARP-1 mediated microglial responses (NO and TNFα) can directly reduce BBB integrity by promoting TJP degradation, increasing endothelial cell permeability and inducing astrogliosis. PARP-1 as a modulator of microglial phenotype can prevent microglial BBB damaging events, and thus is a potential therapeutic target. Copyright © 2017 Elsevier Ltd. All rights reserved.

Differences in amyloid-β clearance across mouse and human blood-brain barrier models: kinetic analysis and mechanistic modeling.

PubMed

Qosa, Hisham; Abuasal, Bilal S; Romero, Ignacio A; Weksler, Babette; Couraud, Pierre-Oliver; Keller, Jeffrey N; Kaddoumi, Amal

2014-04-01

Alzheimer's disease (AD) has a characteristic hallmark of amyloid-β (Aβ) accumulation in the brain. This accumulation of Aβ has been related to its faulty cerebral clearance. Indeed, preclinical studies that used mice to investigate Aβ clearance showed that efflux across blood-brain barrier (BBB) and brain degradation mediate efficient Aβ clearance. However, the contribution of each process to Aβ clearance remains unclear. Moreover, it is still uncertain how species differences between mouse and human could affect Aβ clearance. Here, a modified form of the brain efflux index method was used to estimate the contribution of BBB and brain degradation to Aβ clearance from the brain of wild type mice. We estimated that 62% of intracerebrally injected (125)I-Aβ40 is cleared across BBB while 38% is cleared by brain degradation. Furthermore, in vitro and in silico studies were performed to compare Aβ clearance between mouse and human BBB models. Kinetic studies for Aβ40 disposition in bEnd3 and hCMEC/D3 cells, representative in vitro mouse and human BBB models, respectively, demonstrated 30-fold higher rate of (125)I-Aβ40 uptake and 15-fold higher rate of degradation by bEnd3 compared to hCMEC/D3 cells. Expression studies showed both cells to express different levels of P-glycoprotein and RAGE, while LRP1 levels were comparable. Finally, we established a mechanistic model, which could successfully predict cellular levels of (125)I-Aβ40 and the rate of each process. Established mechanistic model suggested significantly higher rates of Aβ uptake and degradation in bEnd3 cells as rationale for the observed differences in (125)I-Aβ40 disposition between mouse and human BBB models. In conclusion, current study demonstrates the important role of BBB in the clearance of Aβ from the brain. Moreover, it provides insight into the differences between mouse and human BBB with regards to Aβ clearance and offer, for the first time, a mathematical model that describes Aβ clearance across BBB. Copyright © 2014 Elsevier Ltd. All rights reserved.

Differences in amyloid-β clearance across mouse and human blood-brain barrier models: Kinetic analysis and mechanistic modeling

PubMed Central

Qosa, Hisham; Abuasal, Bilal S.; Romero, Ignacio A.; Weksler, Babette; Couraud, Pierre-Oliver; Keller, Jeffrey N.; Kaddoumi, Amal

2014-01-01

Alzheimer’s disease (AD) has a characteristic hallmark of amyloid-β (Aβ) accumulation in the brain. This accumulation of Aβ has been related to its faulty cerebral clearance. Indeed, preclinical studies that used mice to investigate Aβ clearance showed that efflux across blood-brain barrier (BBB) and brain degradation mediate efficient Aβ clearance. However, the contribution of each process to Aβ clearance remains unclear. Moreover, it is still uncertain how species differences between mouse and human could affect Aβ clearance. Here, a modified form of the brain efflux index method was used to estimate the contribution of BBB and brain degradation to Aβ clearance from the brain of wild type mice. We estimated that 62% of intracerebrally injected 125I-Aβ40 is cleared across BBB while 38% is cleared by brain degradation. Furthermore, in vitro and in silico studies were performed to compare Aβ clearance between mouse and human BBB models. Kinetic studies for Aβ40 disposition in bEnd3 and hCMEC/D3 cells, representative in vitro mouse and human BBB models, respectively, demonstrated 30-fold higher rate of 125I-Aβ40 uptake and 15-fold higher rate of degradation by bEnd3 compared to hCMEC/D3 cells. Expression studies showed both cells to express different levels of P-glycoprotein and RAGE, while LRP1 levels were comparable. Finally, we established a mechanistic model, which could successfully predict cellular levels of 125I-Aβ40 and the rate of each process. Established mechanistic model suggested significantly higher rates of Aβ uptake and degradation in bEnd3 cells as rationale for the observed differences in 125I-Aβ40 disposition between mouse and human BBB models. In conclusion, current study demonstrates the important role of BBB in the clearance of Aβ from the brain. Moreover, it provides insight into the differences between mouse and human BBB with regards to Aβ clearance and offer, for the first time, a mathematical model that describes Aβ clearance across BBB. PMID:24467845

In silico modeling on ADME properties of natural products: Classification models for blood-brain barrier permeability, its application to traditional Chinese medicine and in vitro experimental validation.

PubMed

Zhang, Xiuqing; Liu, Ting; Fan, Xiaohui; Ai, Ni

2017-08-01

In silico modeling of blood-brain barrier (BBB) permeability plays an important role in early discovery of central nervous system (CNS) drugs due to its high-throughput and cost-effectiveness. Natural products (NP) have demonstrated considerable therapeutic efficacy against several CNS diseases. However, BBB permeation property of NP is scarcely evaluated both experimentally and computationally. It is well accepted that significant difference in chemical spaces exists between NP and synthetic drugs, which calls into doubt on suitability of available synthetic chemical based BBB permeability models for the evaluation of NP. Herein poor discriminative performance on BBB permeability of NP are first confirmed using internal constructed and previously published drug-derived computational models, which warrants the need for NP-oriented modeling. Then a quantitative structure-property relationship (QSPR) study on a NP dataset was carried out using four different machine learning methods including support vector machine, random forest, Naïve Bayes and probabilistic neural network with 67 selected features. The final consensus model was obtained with approximate 90% overall accuracy for the cross-validation study, which is further taken to predict passive BBB permeability of a large dataset consisting of over 10,000 compounds from traditional Chinese medicine (TCM). For 32 selected TCM molecules, their predicted BBB permeability were evaluated by in vitro parallel artificial membrane permeability assay and overall accuracy for in vitro experimental validation is around 81%. Interestingly, our in silico model successfully predicted different BBB permeation potentials of parent molecules and their known in vivo metabolites. Finally, we found that the lipophilicity, the number of hydrogen bonds and molecular polarity were important molecular determinants for BBB permeability of NP. Our results suggest that the consensus model proposed in current work is a reliable tool for prioritizing potential CNS active NP across the BBB, which would accelerate their development and provide more understanding on their mechanisms, especially those with pharmacologically active metabolites. Copyright © 2017 Elsevier Inc. All rights reserved.

Characteristics of L-citrulline transport through blood-brain barrier in the brain capillary endothelial cell line (TR-BBB cells).

PubMed

Lee, Kyeong-Eun; Kang, Young-Sook

2017-05-10

L -Citrulline is a neutral amino acid and a major precursor of L -arginine in the nitric oxide (NO) cycle. Recently it has been reported that L -citrulline prevents neuronal cell death and protects cerebrovascular injury, therefore, L -citrulline may have a neuroprotective effect to improve cerebrovascular dysfunction. Therefore, we aimed to clarify the brain transport mechanism of L -citrulline through blood-brain barrier (BBB) using the conditionally immortalized rat brain capillary endothelial cell line (TR-BBB cells), as an in vitro model of the BBB. The uptake study of [ 14 C] L-citrulline, quantitative real-time polymerase chain reaction (PCR) analysis, and rLAT1, system b 0,+ , and CAT1 small interfering RNA study were performed in TR-BBB cells. The uptake of [ 14 C] L -citrulline was a time-dependent, but ion-independent manner in TR-BBB cells. The transport process involved two saturable components with a Michaelis-Menten constant of 30.9 ± 1.0 μM (Km 1 ) and 1.69 ± 0.43 mM (Km 2 ). The uptake of [ 14 C] L -citrulline in TR-BBB cells was significantly inhibited by neutral and cationic amino acids, but not by anionic amino acids. In addition, [ 14 C] L -citrulline uptake in the cells was markedly inhibited by 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH), which is the inhibitor of the large neutral amino acid transporter 1 (LAT1), B 0 , B 0,+ and harmaline, the inhibitor of system b 0,+ . Gabapentin and L -dopa as the substrates of LAT1 competitively inhibited the uptake of [ 14 C] L -citrulline. IC 50 values for L -dopa, gabapentin, L -phenylalanine and L -arginine were 501 μM, 223 μM, 68.9 μM and 33.4 mM, respectively. The expression of mRNA for LAT1 was predominantly increased 187-fold in comparison with that of system b 0,+ in TR-BBB cells. In the studies of LAT1, system b 0,+ and CAT1 knockdown via siRNA transfection into TR-BBB cells, the transcript level of LAT1 and [ 14 C] L -citrulline uptake by LAT1 siRNA were significantly reduced compared with those by control siRNA in TR-BBB cells. Our results suggest that transport of L -citrulline is mainly mediated by LAT1 in TR-BBB cells. Delivery strategy for LAT1-mediated transport and supply of L-citrulline to the brain may serve as therapeutic approaches to improve its neuroprotective effect in patients with cerebrovascular disease.

Noninvasive and Targeted Drug Delivery to the Brain Using Focused Ultrasound

PubMed Central

2013-01-01

Brain diseases are notoriously difficult to treat due to the presence of the blood-brain barrier (BBB). Here, we review the development of focused ultrasound (FUS) as a noninvasive method for BBB disruption, aiding in drug delivery to the brain. FUS can be applied through the skull to a targeted region in the brain. When combined with microbubbles, FUS causes localized and reversible disruption of the BBB. The cellular mechanisms of BBB disruption are presented. Several therapeutic agents have been delivered to the brain resulting in significant improvements in pathology in models of glioblastoma and Alzheimer’s disease. The requirements for clinical translation of FUS will be discussed. PMID:23379618

Self-amplification of nigral degeneration in Parkinson's disease: a hypothesis.

PubMed

Ionov, Ilya D

2008-12-01

This review analyzes current evidence regarding possible mechanisms of nigral damage in idiopathic Parkinson's disease (iPD). In normal brain, a specific interplay among the blood-brain barrier (BBB), substantia nigra (SN), and locus coeruleus (LC) creates the condition for a self-accelerating damage to the SN. Three vicious circles involving SN-BBB, LC-SN-BBB, and histamine-BBB-SN interactions are described. In iPD, a self-accelerating loss of nigral cells can be triggered by brain hypoperfusion and by an increased blood histamine level. iPD-associated factors such as decreased CSF levels of substance P, somatostatin, and glutamate can aggravate the vicious-circle-induced damage to the SN.

Dual role of ALCAM in neuroinflammation and blood–brain barrier homeostasis

PubMed Central

Saint-Laurent, Olivia; Bourbonnière, Lyne; Larouche, Sandra; Larochelle, Catherine; Michel, Laure; Charabati, Marc; Abadier, Michael; Zandee, Stephanie; Haghayegh Jahromi, Neda; Gowing, Elizabeth; Pittet, Camille; Lyck, Ruth; Engelhardt, Britta

2017-01-01

Activated leukocyte cell adhesion molecule (ALCAM) is a cell adhesion molecule found on blood–brain barrier endothelial cells (BBB-ECs) that was previously shown to be involved in leukocyte transmigration across the endothelium. In the present study, we found that ALCAM knockout (KO) mice developed a more severe myelin oligodendrocyte glycoprotein (MOG)35–55–induced experimental autoimmune encephalomyelitis (EAE). The exacerbated disease was associated with a significant increase in the number of CNS-infiltrating proinflammatory leukocytes compared with WT controls. Passive EAE transfer experiments suggested that the pathophysiology observed in active EAE was linked to the absence of ALCAM on BBB-ECs. In addition, phenotypic characterization of unimmunized ALCAM KO mice revealed a reduced expression of BBB junctional proteins. Further in vivo, in vitro, and molecular analysis confirmed that ALCAM is associated with tight junction molecule assembly at the BBB, explaining the increased permeability of CNS blood vessels in ALCAM KO animals. Collectively, our data point to a biologically important function of ALCAM in maintaining BBB integrity. PMID:28069965

Theranostic quantum dots for crossing blood–brain barrier in vitro and providing therapy of HIV-associated encephalopathy

PubMed Central

Xu, Gaixia; Mahajan, Supriya; Roy, Indrajit; Yong, Ken-Tye

2013-01-01

The blood–brain barrier (BBB) is a complex physiological checkpoint that restricts the free diffusion of circulating molecules from the blood into the central nervous system. Delivering of drugs and other active agents across the BBB is one of the major technical challenges faced by scientists and medical practitioners. Therefore, development of novel methodologies to address this challenge holds the key for both the diagnosis and treatment of brain diseases, such as HIV-associated encephalopathy. Bioconjugated quantum dots (QDs) are excellent fluorescent probes and nano-vectors, being designed to transverse across the BBB and visualize drug delivery inside the brain. This paper discusses the use of functionalized QDs for crossing the blood–brain barrier and treating brain disease. We highlight the guidelines for using in vitro BBB models for brain disease studies. The theranostic QDs offers a strategy to significantly improve the effective dosages of drugs to transverse across the BBB and orientate to the targets inside the brain. PMID:24298256

Mesenchymal Stem Cells Regulate Blood Brain Barrier Integrity in Traumatic Brain Injury Through Production of the Soluble Factor TIMP3

PubMed Central

Menge, Tyler; Zhao, Yuhai; Zhao, Jing; Wataha, Kathryn; Geber, Michael; Zhang, Jianhu; Letourneau, Phillip; Redell, John; Shen, Li; Wang, Jing; Peng, Zhalong; Xue, Hasen; Kozar, Rosemary; Cox, Charles S.; Khakoo, Aarif Y.; Holcomb, John B.; Dash, Pramod K.; Pati, Shibani

2013-01-01

Mesenchymal stem cells (MCSs) have been shown to have therapeutic potential in multiple disease states associated with vascular instability including traumatic brain injury (TBI). In the present study, Tissue Inhibitor of Matrix Metalloproteinase-3 (TIMP3) is identified as the soluble factor produced by MSCs that can recapitulate the beneficial effects of MSCs on endothelial function and blood brain barrier (BBB) compromise in TBI. Attenuation of TIMP3 expression in MSCs completely abrogates the effect of MSCs on BBB permeability and stability, while intravenous administration of rTIMP3 alone can inhibit BBB permeability in TBI. Our results demonstrate that MSCs increase circulating levels of soluble TIMP3, which inhibits VEGF-A induced breakdown of endothelial AJs in vitro and in vivo. These findings elucidate a clear molecular mechanism for the effects of MSCs on the BBB in TBI, and directly demonstrate a role for TIMP3 in regulation of BBB integrity. PMID:23175708

EMP-induced alterations of tight junction protein expression and disruption of the blood-brain barrier.

PubMed

Ding, Gui-Rong; Qiu, Lian-Bo; Wang, Xiao-Wu; Li, Kang-Chu; Zhou, Yong-Chun; Zhou, Yan; Zhang, Jie; Zhou, Jia-Xing; Li, Yu-Rong; Guo, Guo-Zhen

2010-07-15

The blood-brain barrier (BBB) is critical to maintain cerebral homeostasis. In this study, we examined the effects of exposure to electromagnetic pulse (EMP) on the functional integrity of BBB and, on the localization and expression of tight junction (TJ) proteins (occludin and ZO-1) in rats. Animals were sham or whole-body exposed to EMP at 200 kV/m for 400 pulses. The permeability of BBB in rat cerebral cortex was examined by using Evans Blue (EB) and lanthanum nitrate as vascular tracers. The localization and expression of TJ proteins were assessed by western blot and immunofluorescence analysis, respectively. The data indicated that EMP exposure caused: (i) increased permeability of BBB, and (ii) altered localization as well as decreased levels of TJ protein ZO-1. These results suggested that the alteration of ZO-1 may play an important role in the disruption of tight junctions, which may lead to dysfunction of BBB after EMP exposure. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Tailored delivery of analgesic ziconotide across a blood brain barrier model using viral nanocontainers

NASA Astrophysics Data System (ADS)

Anand, Prachi; O'Neil, Alison; Lin, Emily; Douglas, Trevor; Holford, Mandë

2015-08-01

The blood brain barrier (BBB) is often an insurmountable obstacle for a large number of candidate drugs, including peptides, antibiotics, and chemotherapeutic agents. Devising an adroit delivery method to cross the BBB is essential to unlocking widespread application of peptide therapeutics. Presented here is an engineered nanocontainer for delivering peptidic drugs across the BBB encapsulating the analgesic marine snail peptide ziconotide (Prialt®). We developed a bi-functional viral nanocontainer based on the Salmonella typhimurium bacteriophage P22 capsid, genetically incorporating ziconotide in the interior cavity, and chemically attaching cell penetrating HIV-Tat peptide on the exterior of the capsid. Virus like particles (VLPs) of P22 containing ziconotide were successfully transported in several BBB models of rat and human brain microvascular endothelial cells (BMVEC) using a recyclable noncytotoxic endocytic pathway. This work demonstrates proof in principle for developing a possible alternative to intrathecal injection of ziconotide using a tunable VLP drug delivery nanocontainer to cross the BBB.

Chronic depletion of gonadal testosterone leads to blood-brain barrier dysfunction and inflammation in male mice.

PubMed

Atallah, Afnan; Mhaouty-Kodja, Sakina; Grange-Messent, Valérie

2017-09-01

A dysfunction in the blood-brain barrier (BBB) is associated with many neurological and metabolic disorders. Although sex steroid hormones have been shown to impact vascular tone, endothelial function, oxidative stress, and inflammatory responses, there are still no data on the role of testosterone in the regulation of BBB structure and function. In this context, we investigated the effects of gonadal testosterone depletion on the integrity of capillary BBB and the surrounding parenchyma in male mice. Our results show increased BBB permeability for different tracers and endogenous immunoglobulins in chronically testosterone-depleted male mice. These results were associated with disorganization of tight junction structures shown by electron tomography and a lower amount of tight junction proteins such as claudin-5 and ZO-1. BBB leakage was also accompanied by activation of astrocytes and microglia, and up-regulation of inflammatory molecules such as inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), interleukin 1 beta (IL-1β), and tumor necrosis factor (TNF). Supplementation of castrated male mice with testosterone restored BBB selective permeability, tight junction integrity, and almost completely abrogated the inflammatory features. The present demonstration that testosterone transiently impacts cerebrovascular physiology in adult male mice should help gain new insights into neurological and metabolic diseases linked to hypogonadism in men of all ages.

Circulating angiotensin II gains access to the hypothalamus and brain stem during hypertension via breakdown of the blood-brain barrier.

PubMed

Biancardi, Vinicia Campana; Son, Sook Jin; Ahmadi, Sahra; Filosa, Jessica A; Stern, Javier E

2014-03-01

Angiotensin II-mediated vascular brain inflammation emerged as a novel pathophysiological mechanism in neurogenic hypertension. However, the precise underlying mechanisms and functional consequences in relation to blood-brain barrier (BBB) integrity and central angiotensin II actions mediating neurohumoral activation in hypertension are poorly understood. Here, we aimed to determine whether BBB permeability within critical hypothalamic and brain stem regions involved in neurohumoral regulation was altered during hypertension. Using digital imaging quantification after intravascularly injected fluorescent dyes and immunohistochemistry, we found increased BBB permeability, along with altered key BBB protein constituents, in spontaneously hypertensive rats within the hypothalamic paraventricular nucleus, the nucleus of the solitary tract, and the rostral ventrolateral medulla, all critical brain regions known to contribute to neurohumoral activation during hypertension. BBB disruption, including increased permeability and downregulation of constituent proteins, was prevented in spontaneously hypertensive rats treated with the AT1 receptor antagonist losartan, but not with hydralazine, a direct vasodilator. Importantly, we found circulating angiotensin II to extravasate into these brain regions, colocalizing with neurons and microglial cells. Taken together, our studies reveal a novel angiotensin II-mediated feed-forward mechanism during hypertension, by which circulating angiotensin II evokes increased BBB permeability, facilitating in turn its access to critical brain regions known to participate in blood pressure regulation.

Receptor Targeted Polymeric Nanostructures Capable of Navigating across the Blood-Brain Barrier for Effective Delivery of Neural Therapeutics.

PubMed

Dube, Taru; Chibh, Sonika; Mishra, Jibanananda; Panda, Jiban Jyoti

2017-10-18

The window of neurological maladies encompasses 600 known neurological disorders. In the past few years, an inordinate upsurge in the incidences of neuronal ailments with increased mortality rate has been witnessed globally. Despite noteworthy research in the discovery and development of neural therapeutics, brain drug delivery still encounters limited success due to meager perviousness of most of the drug molecules through the blood-brain barrier (BBB), a tight layer of endothelial cells that selectively impedes routing of the molecules across itself. In this Review, we have tried to present a comprehensive idea on the recent developments in nanoparticle based BBB delivery systems, with a focus on the advancements in receptor targeted polymeric nanoparticles pertaining to BBB delivery. We have also attempted to bridge the gap between conventional brain delivery strategies and nanoparticle based BBB delivery for in-depth understanding. Various strategies are being explored for simplifying delivery of molecules across the BBB; however, they have their own limitations such as invasiveness and need for hospitalization and surgery. Introduction of nanotechnology can impressively benefit brain drug delivery. Though many nanoparticles are being explored, there are still several issues that need to be analyzed scrupulously before a real and efficient BBB traversing nanoformulation is realized.

Blood-brain barrier breakdown promotes macrophage infiltration and cognitive impairment in leptin receptor-deficient mice.

PubMed

Stranahan, Alexis M; Hao, Shuai; Dey, Aditi; Yu, Xiaolin; Baban, Babak

2016-12-01

Accumulating evidence indicates that obesity accelerates the onset of cognitive decline. While mechanisms are still being identified, obesity promotes peripheral inflammation and increases blood-brain barrier (BBB) permeability. However, no studies have manipulated vascular permeability in obesity to determine whether BBB breakdown underlies memory deficits. Protein kinase Cβ (PKCβ) activation destabilizes the BBB, and we used a PKCβ inhibitor (Enzastaurin) to block BBB leakiness in leptin receptor-deficient (db/db) mice. Enzastaurin reversed BBB breakdown in db/db mice and normalized hippocampal function without affecting obesity or metabolism. Flow cytometric analysis of forebrain mononuclear cells (FMCs) from db/db mice revealed macrophage infiltration and induction of the activation marker MHCII in microglia and macrophages. Enzastaurin eliminated macrophage infiltration and MHCII induction, and protein array profiling revealed parallel reductions in IL1β, IL6, MCP1, and TNFα. To investigate whether these signals attract peripheral monocytes, FMCs from Wt and db/db mice were plated below migration inserts containing peritoneal macrophages. Peritoneal macrophages from db/db mice exhibit increases in transmigration that were blocked by recombinant IL1RA. These studies indicate that BBB breakdown impairs cognition in obesity and diabetes by allowing macrophage infiltration, with a potential role for IL1β in trafficking of peripheral monocytes into the brain. © The Author(s) 2016.

Isoflurane anesthesia results in reversible ultrastructure and occludin tight junction protein expression changes in hippocampal blood-brain barrier in aged rats.

PubMed

Cao, Yiyun; Ni, Cheng; Li, Zhengqian; Li, Lunxu; Liu, Yajie; Wang, Chunyi; Zhong, Yanfeng; Cui, Dehua; Guo, Xiangyang

2015-02-05

The underlying mechanism of isoflurane-induced cognitive dysfunction in older individuals is unknown. In this study, the effects of isoflurane exposure on the hippocampal blood-brain barrier (BBB) in aged rats were investigated because it was previously shown that BBB disruption involves in cognitive dysfunction. Twenty-month-old rats randomly received 1.5% isoflurane or vehicle gas as control. Hippocampal BBB ultrastructure was analyzed by transmission electron microscopy and expression of tight junction proteins was measured by western blot analysis. BBB permeability was detected with sodium fluorescein extravasation and further confirmed by immunoglobulin G immunohistochemistry. Spatial learning and memory were assessed by the Morris water maze test. Isoflurane anesthesia resulted in reversible time-dependent BBB ultrastructure morphological damage and significant decreases in expression of the tight junction proteins occludin, which contributed to sodium fluorescein and IgG leakage. Rats with isoflurane exposure also showed significant cognitive deficits in the Morris water maze test. This in vivo data indicate that occludin down-regulation may be one of the mediators of isoflurane-induced hippocampus BBB disruption, and may contribute to hippocampus-dependent cognitive impairment after isoflurane exposure in aged rats. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

A Genetic Algorithm Based Support Vector Machine Model for Blood-Brain Barrier Penetration Prediction

PubMed Central

Zhang, Daqing; Xiao, Jianfeng; Zhou, Nannan; Luo, Xiaomin; Jiang, Hualiang; Chen, Kaixian

2015-01-01

Blood-brain barrier (BBB) is a highly complex physical barrier determining what substances are allowed to enter the brain. Support vector machine (SVM) is a kernel-based machine learning method that is widely used in QSAR study. For a successful SVM model, the kernel parameters for SVM and feature subset selection are the most important factors affecting prediction accuracy. In most studies, they are treated as two independent problems, but it has been proven that they could affect each other. We designed and implemented genetic algorithm (GA) to optimize kernel parameters and feature subset selection for SVM regression and applied it to the BBB penetration prediction. The results show that our GA/SVM model is more accurate than other currently available log BB models. Therefore, to optimize both SVM parameters and feature subset simultaneously with genetic algorithm is a better approach than other methods that treat the two problems separately. Analysis of our log BB model suggests that carboxylic acid group, polar surface area (PSA)/hydrogen-bonding ability, lipophilicity, and molecular charge play important role in BBB penetration. Among those properties relevant to BBB penetration, lipophilicity could enhance the BBB penetration while all the others are negatively correlated with BBB penetration. PMID:26504797

Excitotoxicity triggered by neonatal monosodium glutamate treatment and blood-brain barrier function.

PubMed

Gudiño-Cabrera, Graciela; Ureña-Guerrero, Monica E; Rivera-Cervantes, Martha C; Feria-Velasco, Alfredo I; Beas-Zárate, Carlos

2014-11-01

It is likely that monosodium glutamate (MSG) is the excitotoxin that has been most commonly employed to characterize the process of excitotoxicity and to improve understanding of the ways that this process is related to several pathological conditions of the central nervous system. Excitotoxicity triggered by neonatal MSG treatment produces a significant pathophysiological impact on adulthood, which could be due to modifications in the blood-brain barrier (BBB) permeability and vice versa. This mini-review analyzes this topic through brief descriptions about excitotoxicity, BBB structure and function, role of the BBB in the regulation of Glu extracellular levels, conditions that promote breakdown of the BBB, and modifications induced by neonatal MSG treatment that could alter the behavior of the BBB. In conclusion, additional studies to better characterize the effects of neonatal MSG treatment on excitatory amino acids transporters, ionic exchangers, and efflux transporters, as well as the role of the signaling pathways mediated by erythropoietin and vascular endothelial growth factor in the cellular elements of the BBB, should be performed to identify the mechanisms underlying the increase in neurovascular permeability associated with excitotoxicity observed in several diseases and studied using neonatal MSG treatment. Copyright © 2015 IMSS. Published by Elsevier Inc. All rights reserved.

The role of multidrug resistance protein (MRP-1) as an active efflux transporter on blood-brain barrier (BBB) permeability.

PubMed

Lingineni, Karthik; Belekar, Vilas; Tangadpalliwar, Sujit R; Garg, Prabha

2017-05-01

Drugs acting on central nervous system (CNS) may take longer duration to reach the market as these compounds have a higher attrition rate in clinical trials due to the complexity of the brain, side effects, and poor blood-brain barrier (BBB) permeability compared to non-CNS-acting compounds. The roles of active efflux transporters with BBB are still unclear. The aim of the present work was to develop a predictive model for BBB permeability that includes the MRP-1 transporter, which is considered as an active efflux transporter. A support vector machine model was developed for the classification of MRP-1 substrates and non-substrates, which was validated with an external data set and Y-randomization method. An artificial neural network model has been developed to evaluate the role of MRP-1 on BBB permeation. A total of nine descriptors were selected, which included molecular weight, topological polar surface area, ClogP, number of hydrogen bond donors, number of hydrogen bond acceptors, number of rotatable bonds, P-gp, BCRP, and MRP-1 substrate probabilities for model development. We identified 5 molecules that fulfilled all criteria required for passive permeation of BBB, but they all have a low logBB value, which suggested that the molecules were effluxed by the MRP-1 transporter.

In Vitro Cerebrovascular Modeling in the 21st Century: Current and Prospective Technologies

PubMed Central

Palmiotti, Christopher A.; Prasad, Shikha; Naik, Pooja; Abul, Kaisar MD; Sajja, Ravi K.; Achyuta, Anilkumar H.; Cucullo, Luca

2014-01-01

The blood-brain barrier (BBB) maintains the brain homeostasis and dynamically responds to events associated with systemic and/or rheological impairments (e.g., inflammation, ischemia) including the exposure to harmful xenobiotics. Thus, understanding the BBB physiology is crucial for the resolution of major central nervous system CNS) disorders challenging both health care providers and the pharmaceutical industry. These challenges include drug delivery to the brain, neurological disorders, toxicological studies, and biodefense. Studies aimed at advancing our understanding of CNS diseases and promoting the development of more effective therapeutics are primarily performed in laboratory animals. However, there are major hindering factors inherent to in vivo studies such as cost, limited throughput and translational significance to humans. These factors promoted the development of alternative in vitro strategies for studying the physiology and pathophysiology of the BBB in relation to brain disorders as well as screening tools to aid in the development of novel CNS drugs. Herein, we provide a detailed review including pros and cons of current and prospective technologies for modelling the BBB in vitro including ex situ, cell based and computational (in silico) models. A special section is dedicated to microfluidic systems including micro-BBB, BBB-on-a-chip, Neurovascular Unit-on-a-Chip and Synthetic Microvasculature Blood-Brain Barrier. PMID:25098812

In vitro cerebrovascular modeling in the 21st century: current and prospective technologies.

PubMed

Palmiotti, Christopher A; Prasad, Shikha; Naik, Pooja; Abul, Kaisar M D; Sajja, Ravi K; Achyuta, Anilkumar H; Cucullo, Luca

2014-12-01

The blood-brain barrier (BBB) maintains the brain homeostasis and dynamically responds to events associated with systemic and/or rheological impairments (e.g., inflammation, ischemia) including the exposure to harmful xenobiotics. Thus, understanding the BBB physiology is crucial for the resolution of major central nervous system CNS) disorders challenging both health care providers and the pharmaceutical industry. These challenges include drug delivery to the brain, neurological disorders, toxicological studies, and biodefense. Studies aimed at advancing our understanding of CNS diseases and promoting the development of more effective therapeutics are primarily performed in laboratory animals. However, there are major hindering factors inherent to in vivo studies such as cost, limited throughput and translational significance to humans. These factors promoted the development of alternative in vitro strategies for studying the physiology and pathophysiology of the BBB in relation to brain disorders as well as screening tools to aid in the development of novel CNS drugs. Herein, we provide a detailed review including pros and cons of current and prospective technologies for modelling the BBB in vitro including ex situ, cell based and computational (in silico) models. A special section is dedicated to microfluidic systems including micro-BBB, BBB-on-a-chip, Neurovascular Unit-on-a-Chip and Synthetic Microvasculature Blood-brain Barrier.

Altered expression of zonula occludens-2 precedes increased blood-brain barrier permeability in a murine model of fulminant hepatic failure.

PubMed

Shimojima, Naoki; Eckman, Christopher B; McKinney, Michael; Sevlever, Daniel; Yamamoto, Satoshi; Lin, Wenlang; Dickson, Dennis W; Nguyen, Justin H

2008-01-01

Brain edema secondary to increased blood-brain barrier (BBB) permeability is a lethal complication in fulminant hepatic failure (FHF). Intact tight junctions (TJ) between brain capillary endothelial cells are critical for normal BBB function. However, the role of TJ in FHF has not been explored. We hypothesized that alterations in the composition of TJ proteins would result in increased BBB permeability in FHF. In this study, FHF was induced in C57BL/6J mice by using azoxymethane. BBB permeability was assessed with sodium fluorescein. Expression of TJ proteins was determined by Western blot, and their cellular distribution was examined using immunofluorescent microscopy. Comatose FHF mice had significant cerebral sodium fluorescein extravasation compared with control and precoma FHF mice, indicating increased BBB permeability. Western blot analysis showed a significant decrease in zonula occludens (ZO)-2 expression starting in the precoma stage. Immunofluorescent microscopy showed a significantly altered distribution pattern of ZO-2 in isolated microvessels from precoma FHF mice. These changes were more prominent in comatose FHF animals. Significant alterations in ZO-2 expression and distribution in the tight junctions preceded the increased BBB permeability in FHF mice. These results suggest that ZO-2 may play an important role in the pathogenesis of brain edema in FHF.

An isogenic blood-brain barrier model comprising brain endothelial cells, astrocytes, and neurons derived from human induced pluripotent stem cells.

PubMed

Canfield, Scott G; Stebbins, Matthew J; Morales, Bethsymarie Soto; Asai, Shusaku W; Vatine, Gad D; Svendsen, Clive N; Palecek, Sean P; Shusta, Eric V

2017-03-01

The blood-brain barrier (BBB) is critical in maintaining a physical and metabolic barrier between the blood and the brain. The BBB consists of brain microvascular endothelial cells (BMECs) that line the brain vasculature and combine with astrocytes, neurons and pericytes to form the neurovascular unit. We hypothesized that astrocytes and neurons generated from human-induced pluripotent stem cells (iPSCs) could induce BBB phenotypes in iPSC-derived BMECs, creating a robust multicellular human BBB model. To this end, iPSCs were used to form neural progenitor-like EZ-spheres, which were in turn differentiated to neurons and astrocytes, enabling facile neural cell generation. The iPSC-derived astrocytes and neurons induced barrier tightening in primary rat BMECs indicating their BBB inductive capacity. When co-cultured with human iPSC-derived BMECs, the iPSC-derived neurons and astrocytes significantly elevated trans-endothelial electrical resistance, reduced passive permeability, and improved tight junction continuity in the BMEC cell population, while p-glycoprotein efflux transporter activity was unchanged. A physiologically relevant neural cell mixture of one neuron: three astrocytes yielded optimal BMEC induction properties. Finally, an isogenic multicellular BBB model was successfully demonstrated employing BMECs, astrocytes, and neurons from the same donor iPSC source. It is anticipated that such an isogenic facsimile of the human BBB could have applications in furthering understanding the cellular interplay of the neurovascular unit in both healthy and diseased humans. Read the Editorial Highlight for this article on page 843. © 2016 International Society for Neurochemistry.

Evidence for differential changes of junctional complex proteins in murine neurocysticercosis dependent upon CNS vasculature.

PubMed

Alvarez, Jorge I; Teale, Judy M

2007-09-12

The delicate balance required to maintain homeostasis of the central nervous system (CNS) is controlled by the blood-brain barrier (BBB). Upon injury, the BBB is disrupted compromising the CNS. BBB disruption has been represented as a uniform event. However, our group has shown in a murine model of neurocysticercosis (NCC) that BBB disruption varies depending upon the anatomical site/vascular bed analyzed. In this study further understanding of the mechanisms of BBB disruption was explored in blood vessels located in leptomeninges (pial vessels) and brain parenchyma (parenchymal vessels) by examining the expression of junctional complex proteins in murine brain infected with Mesocestoides corti. Both pial and parenchymal vessels from mock infected animals showed significant colocalization of junctional proteins and displayed an organized architecture. Upon infection, the patterned organization was disrupted and in some cases, particular tight junction and adherens junction proteins were undetectable or appeared to be undergoing proteolysis. The extent and timing of these changes differed between both types of vessels (pial vessel disruption within days versus weeks for parenchymal vessels). To approach potential mechanisms, the expression and activity of matrix metalloproteinase-9 (MMP-9) were evaluated by in situ zymography. The results indicated an increase in MMP-9 activity at sites of BBB disruption exhibiting leukocyte infiltration. Moreover, the timing of MMP activity in pial and parenchymal vessels correlated with the timing of permeability disruption. Thus, breakdown of the BBB is a mutable process despite the similar structure of the junctional complex between pial and parenchymal vessels and involvement of MMP activity.

Enhancing the Delivery of Anti Retroviral Drug “Saquinavir” Across the Blood Brain Barrier Using Nanoparticles

PubMed Central

Mahajan, Supriya D.; Roy, Indrajit; Xu, GaiXia; Yong, Ken-Tye; Ding, Hong; Aalinkeel, Ravikumar; Reynolds, Jessica L.; Sykes, Donald E.; Nair, Bindukumar B.; Lin, Elaine Y.; Prasad, Paras N.; Schwartz, Stanley A.

2010-01-01

Antiretroviral drugs are ineffective at treating viral infection in the brain because they cannot freely diffuse across the blood-brain barrier (BBB). Therefore, HIV-1 viral replication persists in the central nervous system (CNS) and continues to augment the neuropathogenesis process. Nanotechnology can play a pivotal role in HIV-1 therapeutics as it can increase drug solubility, enhance systemic bioavailability, and at the same time offer multifunctionality. Moreover, following conjugation with transferrin (Tf), these drug-loaded nanoformulations can permeate across biological barriers such as the blood brain barrier (BBB) via a receptor mediated transport mechanism. In the current study, we have stably incorporated the antiviral drug, Saquinavir, within Tf-conjugated quantum rods (QRs), which are novel nanoparticles with unique optical properties. We have evaluated the transversing ability of the QR-Tf-Saquinavir nanoformulation across an in vitro model of BBB. In addition, we have analyzed the subsequent antiviral efficacy of this targeted nanoformulation in HIV-1 infected peripheral blood mononuclear cells (PBMCs), which are cultured on the basolateral end of the in vitro BBB model. Our results show a significant uptake of QR-Tf-Saquinavir by brain microvascular endothelial cells (BMVECs), which constitute the BBB. In addition, we observed a significant enhancement in the transversing capability of QR-Tf-Saquinavir across the BBB, along with a marked decrease in HIV-1 viral replication in the PBMCs. These observations indicate that drug-loaded nanoparticles can deliver therapeutics across the BBB. These results highlight the potential of this nanoformulation in the treatment of Neuro-AIDS and other neurological disorders. PMID:20426757

Optically enhanced blood-brain-barrier crossing of plasmonic-active nanoparticles in preclinical brain tumor animal models

NASA Astrophysics Data System (ADS)

Yuan, Hsiangkuo; Wilson, Christy M.; Li, Shuqin; Fales, Andrew M.; Liu, Yang; Grant, Gerald; Vo-Dinh, Tuan

2014-02-01

Nanotechnology provides tremendous biomedical opportunities for cancer diagnosis, imaging, and therapy. In contrast to conventional chemotherapeutic agents where their actual target delivery cannot be easily imaged, integrating imaging and therapeutic properties into one platform facilitates the understanding of pharmacokinetic profiles, and enables monitoring of the therapeutic process in each individual. Such a concept dubbed "theranostics" potentiates translational research and improves precision medicine. One particular challenging application of theranostics involves imaging and controlled delivery of nanoplatforms across blood-brain-barrier (BBB) into brain tissues. Typically, the BBB hinders paracellular flux of drug molecules into brain parenchyma. BBB disrupting agents (e.g. mannitol, focused ultrasound), however, suffer from poor spatial confinement. It has been a challenge to design a nanoplatform not only acts as a contrast agent but also improves the BBB permeation. In this study, we demonstrated the feasibility of plasmonic gold nanoparticles as both high-resolution optical contrast agent and focalized tumor BBB permeation-inducing agent. We specifically examined the microscopic distribution of nanoparticles in tumor brain animal models. We observed that most nanoparticles accumulated at the tumor periphery or perivascular spaces. Nanoparticles were present in both endothelial cells and interstitial matrices. This study also demonstrated a novel photothermal-induced BBB permeation. Fine-tuning the irradiating energy induced gentle disruption of the vascular integrity, causing short-term extravasation of nanomaterials but without hemorrhage. We conclude that our gold nanoparticles are a powerful biocompatible contrast agent capable of inducing focal BBB permeation, and therefore envision a strong potential of plasmonic gold nanoparticle in future brain tumor imaging and therapy.

Identification of a Novel Indoline Derivative for in Vivo Fluorescent Imaging of Blood-Brain Barrier Disruption in Animal Models

PubMed Central

2013-01-01

Disruption of the blood-brain barrier (BBB) can occur in various pathophysiological conditions. Administration of extraneous tracers that can pass the disrupted, but not the intact, BBB and detection of the extravasation have been widely used to assess BBB disruption in animal models. Although several fluorescent tracers have been successfully used, the administration of these tracers basically requires intravascular injection, which can be laborious when using small animals such as zebrafish. To identify fluorescent tracers that could be easily administered into various animal models and visualize the BBB disruption in vivo, we prepared nine structurally related indoline derivatives (IDs) as a minimum set of diverse fluorescent compounds. We found that one ID, ZMB741, had the highest affinity for serum albumin and emitted the strongest fluorescence in the presence of serum albumin of the nine IDs tested. The affinity to serum albumin and the fluorescence intensity was superior to those of Evans blue and indocyanine green that have been conventionally used to assess the BBB disruption. We showed that ZMB741 could be administered into zebrafish by static immersion or mice by intraperitoneal injection and visualizes the active disruption of their BBB. These results suggest that ZMB741 can be a convenient and versatile tool for in vivo fluorescent imaging of BBB disruption in various animal models. The strategy used in this study can also be applied to diversity-oriented libraries to identify novel fluorescent tracers that may be superior to ZMB741. PMID:23668665

bFGF Protects Against Blood-Brain Barrier Damage Through Junction Protein Regulation via PI3K-Akt-Rac1 Pathway Following Traumatic Brain Injury.

PubMed

Wang, Zhou-Guang; Cheng, Yi; Yu, Xi-Chong; Ye, Li-Bing; Xia, Qing-Hai; Johnson, Noah R; Wei, Xiaojie; Chen, Da-Qing; Cao, Guodong; Fu, Xiao-Bing; Li, Xiao-Kun; Zhang, Hong-Yu; Xiao, Jian

2016-12-01

Many traumatic brain injury (TBI) survivors sustain neurological disability and cognitive impairments due to the lack of defined therapies to reduce TBI-induced blood-brain barrier (BBB) breakdown. Exogenous basic fibroblast growth factor (bFGF) has been shown to have neuroprotective function in brain injury. The present study therefore investigates the beneficial effects of bFGF on the BBB after TBI and the underlying mechanisms. In this study, we demonstrate that bFGF reduces neurofunctional deficits and preserves BBB integrity in a mouse model of TBI. bFGF suppresses RhoA and upregulates tight junction proteins, thereby mitigating BBB breakdown. In vitro, bFGF exerts a protective effect on BBB by upregulating tight junction proteins claudin-5, occludin, zonula occludens-1, p120-catenin, and β-catenin under oxygen glucose deprivation/reoxygenation (OGD) in human brain microvascular endothelial cells (HBMECs). Both the in vivo and in vitro effects are related to the activation of the downstream signaling pathway, PI3K/Akt/Rac-1. Inhibition of the PI3K/Akt or Rac-1 by specific inhibitors LY294002 or si-Rac-1, respectively, partially reduces the protective effect of bFGF on BBB integrity. Overall, our results indicate that the protective role of bFGF on BBB involves the regulation of tight junction proteins and RhoA in the TBI model and OGD-induced HBMECs injury, and that activation of the PI3K/Akt /Rac-1 signaling pathway underlies these effects.

Detrimental effect of electromagnetic pulse exposure on permeability of in vitro blood-brain-barrier model.

PubMed

Zhou, Jia Xing; Ding, Gui Rong; Zhang, Jie; Zhou, Yong Chun; Zhang, Yan Jun; Guo, Guo Zhen

2013-02-01

To study the effect of electromagnetic pulse (EMP) exposure on permeability of in vitro blood-brain-barrier (BBB) model. An in vitro BBB model, established by co-culturing brain microvascular endothelial cells (BMVEC) and astroglial cells (AC) isolated from rat brain, was exposed to EMP at 100 kV/m and 400 kV/m, respectively. Permeability of the model was assayed by measuring the transendothelial electrical resistance (TEER) and the horseradish peroxidase (HRP) transmission at different time points. Levels of BBB tight junction-related proteins were measured at 0, 1, 2, 4, 8, 12, 16, 20, 24 h after EMP exposure by Western blotting. The TEER level was lower in BBB model group than in control group at 12 h after EMP, exposure which returned to its normal level at 24 h. The 24 h recovery process was triphasic and biphasic respectively after EMP exposure at 100 kV/m and 400 kV/m. Following exposure to 400 kV/m EMP, the HRP permeability increased at 1-12 h and returned to its normal level at 24 h. Western blotting showed that the claudin-5 and ZO-1 protein levels were changed after EMP exposure. EMP exposure at 100 kV/m and 400 kV/m can increase the permeability of in vitro BBB model and BBB tight junction-related proteins such as ZO-1 and claudin-5 may change EMP-induced BBB permeability. Copyright © 2013 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Coexistence of passive and proton antiporter-mediated processes in nicotine transport at the mouse blood-brain barrier.

PubMed

Cisternino, Salvatore; Chapy, Hélène; André, Pascal; Smirnova, Maria; Debray, Marcel; Scherrmann, Jean-Michel

2013-04-01

Nicotine, the main tobacco alkaloid leading to smoking dependence, rapidly crosses the blood-brain barrier (BBB) to become concentrated in the brain. Recently, it has been shown that nicotine interacts with some organic cation transporters (OCT), but their influence at the BBB has not yet been assessed in vivo. In this study, we characterized the transport of nicotine at the mouse luminal BBB by in situ brain perfusion. Its influx was saturable and followed the Michaelis-Menten kinetics (K(m)=2.60 mM, V(max)=37.60 nmol/s/g at pH 7.40). At its usual micromolar concentrations in the plasma, most (79%) of the net transport of nicotine at the BBB was carrier-mediated, while passive diffusion accounted for 21%. Studies on knockout mice showed that the OCT Oct1-3, P-gp, and Bcrp did not alter [(3)H]-nicotine transport at the BBB. Neither did inhibiting the transporters Mate1, Octn, or Pmat. The in vivo manipulation of intracellular and/or extracellular pH, the chemical inhibition profile, and the trans-stimulation experiments demonstrated that the nicotine transporter at the BBB shared the properties of the clonidine/proton antiporter. The molecular features of this proton-coupled antiporter have not yet been identified, but it also transports diphenhydramine and tramadol and helps nicotine cross the BBB at a faster rate and to a greater extent. The pharmacological inhibition of this nicotine/proton antiporter could represent a new strategy to reduce nicotine uptake by the brain and thus help curb addiction to smoking.

Prognostic significance of blood-brain barrier disruption in patients with severe nonpenetrating traumatic brain injury requiring decompressive craniectomy.

PubMed

Ho, Kwok M; Honeybul, Stephen; Yip, Cheng B; Silbert, Benjamin I

2014-09-01

The authors assessed the risk factors and outcomes associated with blood-brain barrier (BBB) disruption in patients with severe, nonpenetrating, traumatic brain injury (TBI) requiring decompressive craniectomy. At 2 major neurotrauma centers in Western Australia, a retrospective cohort study was conducted among 97 adult neurotrauma patients who required an external ventricular drain (EVD) and decompressive craniectomy during 2004-2012. Glasgow Outcome Scale scores were used to assess neurological outcomes. Logistic regression was used to identify factors associated with BBB disruption, defined by a ratio of total CSF protein concentrations to total plasma protein concentration > 0.007 in the earliest CSF specimen collected after TBI. Of the 252 patients who required decompressive craniectomy, 97 (39%) required an EVD to control intracranial pressure, and biochemical evidence of BBB disruption was observed in 43 (44%). Presence of disruption was associated with more severe TBI (median predicted risk for unfavorable outcome 75% vs 63%, respectively; p = 0.001) and with worse outcomes at 6, 12, and 18 months than was absence of BBB disruption (72% vs 37% unfavorable outcomes, respectively; p = 0.015). The only risk factor significantly associated with increased risk for BBB disruption was presence of nonevacuated intracerebral hematoma (> 1 cm diameter) (OR 3.03, 95% CI 1.23-7.50; p = 0.016). Although BBB disruption was associated with more severe TBI and worse long-term outcomes, when combined with the prognostic information contained in the Corticosteroid Randomization after Significant Head Injury (CRASH) prognostic model, it did not seem to add significant prognostic value (area under the receiver operating characteristic curve 0.855 vs 0.864, respectively; p = 0.453). Biochemical evidence of BBB disruption after severe nonpenetrating TBI was common, especially among patients with large intracerebral hematomas. Disruption of the BBB was associated with more severe TBI and worse long-term outcomes, but when combined with the prognostic information contained in the CRASH prognostic model, this information did not add significant prognostic value.

The interleukins-1 alpha, -1 beta, and -2 do not acutely disrupt the murine blood-brain barrier.

PubMed

Banks, W A; Kastin, A J

1992-05-01

Previous studies have suggested that some of the central nervous system (CNS) effects of interleukin-2 (IL-2) and perhaps other cytokines might be mediated through disruption of the blood-brain barrier (BBB). We investigated the ability of human IL-2 and, in selected studies, human IL-1 alpha and human IL-1 beta to disrupt the BBB to radioiodinated bovine serum albumin (RISA) after intravenous (i.v.) and intracerebroventricular (i.c.v.) injection. No disruption of the BBB occurred for up to 2 h after the i.v. injection of 2 micrograms/mouse of IL-2 (10(5) U/kg of body weight), 2 micrograms of IL-1 alpha (10(7) U/kg), or 2 micrograms of IL-1 beta (10(7) U/kg). This dose of i.v. IL-2 also did not affect BBB permeability to RISA in the brain to blood direction. Damage to the BBB induced by hypertension elicited by i.v. epinephrine was not enhanced or prolonged by IL-2. When given directly into the CNS by the i.c.v. route, 100 ng of IL-2 (2.2 x 10(5) U/kg of brain), 100 ng of IL-1 alpha (2.2 x 10(7) U/kg of brain), or 100 ng of IL-1 beta (2.2 x 10(7) U/kg of brain) had no effect on BBB integrity in either the blood to brain or the brain to blood direction. We conclude that the effects of IL-1 alpha, IL-1 beta, and IL-2 on the CNS, as studied under these conditions, are not due to disruption of the BBB but are mediated by other mechanisms including the ability of some interleukins to cross the BBB by a saturable transport system described previously.

Mimicking brain tissue binding in an in vitro model of the blood-brain barrier illustrates differences between in vitro and in vivo methods for assessing the rate of brain penetration.

PubMed

Heymans, Marjolein; Sevin, Emmanuel; Gosselet, Fabien; Lundquist, Stefan; Culot, Maxime

2018-06-01

Assessing the rate of drug delivery to the central nervous system (CNS) in vitro has been used for decades to predict whether CNS drug candidates are likely to attain their pharmacological targets, located within the brain parenchyma, at an effective dose. The predictive value of in vitro blood-brain barrier (BBB) models is therefore frequently assessed by comparing in vitro BBB permeability, usually quoted as the endothelial permeability coefficient (P e ) or apparent permeability (P app ), to their rate of BBB permeation measured in vivo, the latter being commonly assessed in rodents. In collaboration with AstraZeneca (DMPK department, Södertälje, Sweden), the in vitro BBB permeability (P app and P e ) of 27 marketed CNS drugs has been determined using a bovine in vitro BBB model and compared to their in vivo permeability (P vivo ), obtained by rat in-situ brain perfusion. The latter was taken from published data from Summerfield et al. (2007). This comparison confirmed previous reports, showing a strong in vitro/in vivo correlation for hydrophilic compounds, characterized by low brain tissue binding and a weak correlation for lipophilic compounds, characterized by high brain tissue binding. This observation can be explained by the influence of brain tissue binding on the uptake of drugs into the CNS in vivo and the absence of possible brain tissue binding in vitro. The use of glial cells (GC) in the in vitro BBB model to mimic brain tissue binding and the introduction of a new calculation method for in vitro BBB permeability (P vitro ) resulted in a strong correlation between the in vitro and in vivo rate of BBB permeation for the whole set of compounds. These findings might facilitate further in vitro to in vivo extrapolation for CNS drug candidates. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Tissue sparing, behavioral recovery, supraspinal axonal sparing/regeneration following sub-acute glial transplantation in a model of spinal cord contusion.

PubMed

Barbour, Helen R; Plant, Christine D; Harvey, Alan R; Plant, Giles W

2013-09-27

It has been shown that olfactory ensheathing glia (OEG) and Schwann cell (SCs) transplantation are beneficial as cellular treatments for spinal cord injury (SCI), especially acute and sub-acute time points. In this study, we transplanted DsRED transduced adult OEG and SCs sub-acutely (14 days) following a T10 moderate spinal cord contusion injury in the rat. Behaviour was measured by open field (BBB) and horizontal ladder walking tests to ascertain improvements in locomotor function. Fluorogold staining was injected into the distal spinal cord to determine the extent of supraspinal and propriospinal axonal sparing/regeneration at 4 months post injection time point. The purpose of this study was to investigate if OEG and SCs cells injected sub acutely (14 days after injury) could: (i) improve behavioral outcomes, (ii) induce sparing/regeneration of propriospinal and supraspinal projections, and (iii) reduce tissue loss. OEG and SCs transplanted rats showed significant increased locomotion when compared to control injury only in the open field tests (BBB). However, the ladder walk test did not show statistically significant differences between treatment and control groups. Fluorogold retrograde tracing showed a statistically significant increase in the number of supraspinal nuclei projecting into the distal spinal cord in both OEG and SCs transplanted rats. These included the raphe, reticular and vestibular systems. Further pairwise multiple comparison tests also showed a statistically significant increase in raphe projecting neurons in OEG transplanted rats when compared to SCs transplanted animals. Immunohistochemistry of spinal cord sections short term (2 weeks) and long term (4 months) showed differences in host glial activity, migration and proteoglycan deposits between the two cell types. Histochemical staining revealed that the volume of tissue remaining at the lesion site had increased in all OEG and SCs treated groups. Significant tissue sparing was observed at both time points following glial SCs transplantation. In addition, OEG transplants showed significantly decreased chondroitin proteoglycan synthesis in the lesion site, suggesting a more CNS tolerant graft. These results show that transplantation of OEG and SCs in a sub-acute phase can improve anatomical outcomes after a contusion injury to the spinal cord, by increasing the number of spared/regenerated supraspinal fibers, reducing cavitation and enhancing tissue integrity. This provides important information on the time window of glial transplantation for the repair of the spinal cord.

Localized delivery of curcumin into brain with polysorbate 80-modified cerasomes by ultrasound-targeted microbubble destruction for improved Parkinson's disease therapy

PubMed Central

Zhang, Nisi; Yan, Fei; Liang, Xiaolong; Wu, Manxiang; Shen, Yuanyuan; Chen, Min; Xu, Yunxue; Zou, Guangyang; Jiang, Peng; Tang, Caiyun; Zheng, Hairong; Dai, Zhifei

2018-01-01

Rationale: Treatment for Parkinson's disease (PD) is challenged by the presence of the blood-brain barrier (BBB) that significantly limits the effective drug concentration in a patient's brain for therapeutic response throughout various stages of PD. Curcumin holds the potential for α-synuclein clearance to treat PD; however, its applications are still limited due to its low bioavailability and poor permeability through the BBB in a free form. Methods: Herein, this paper fabricated curcumin-loaded polysorbate 80-modified cerasome (CPC) nanoparticles (NPs) with a mean diameter of ~110 nm for enhancing the localized curcumin delivery into the targeted brain nuclei via effective BBB opening in combination with ultrasound-targeted microbubble destruction (UTMD). Results: The liposomal nanohybrid cerasome exhibited superior stability towards PS 80 surfactant solubilization and longer circulation lifetime (t1/2 = 6.22 h), much longer than free curcumin (t1/2 = 0.76 h). The permeation was found to be 1.7-fold higher than that of CPC treatment only at 6 h after the systemic administration of CPC NPs. Notably, motor behaviors, dopamine (DA) level and tyrosine hydroxylase (TH) expression all returned to normal, thanks to α-synuclein (AS) removal mediated by efficient curcumin delivery to the striatum. Most importantly, the animal experiment demonstrated that the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice had notably improved behavior disorder and dopamine depletion during two-week post-observation after treatment with CPC NPs (15 mg curcumin/kg) coupled with UTMD. Conclusion: This novel CPC-UTMD formulation approach could be an effective, safe and amenable choice with higher therapeutic relevance and fewer unwanted complications than conventional chemotherapeutics delivery systems for PD treatment in the near future. PMID:29721078

Chemically-defined camelid antibody bioconjugate for the magnetic resonance imaging of Alzheimer's disease.

PubMed

Vandesquille, Matthias; Li, Tengfei; Po, Chrystelle; Ganneau, Christelle; Lenormand, Pascal; Dudeffant, Clémence; Czech, Christian; Grueninger, Fiona; Duyckaerts, Charles; Delatour, Benoît; Dhenain, Marc; Lafaye, Pierre; Bay, Sylvie

Today, molecular imaging of neurodegenerative diseases is mainly based on small molecule probes. Alternatively, antibodies are versatile tools that may be developed as new imaging agents. Indeed, they can be readily obtained to specifically target any antigen of interest and their scaffold can be functionalized. One of the critical issues involved in translating antibody-based probes to the clinic is the design and synthesis of perfectly-defined conjugates. Camelid single-domain antibody-fragments (VHHs) are very small and stable antibodies that are able to diffuse in tissues and potentially cross the blood brain barrier (BBB). Here, we selected a VHH (R3VQ) specifically targeting one of the main lesions of Alzheimer's disease (AD), namely the amyloid-beta (Aß) deposits. It was used as a scaffold for the design of imaging probes for magnetic resonance imaging (MRI) and labeled with the contrastophore gadolinium using either a random or site-specific approach. In contrast to the random strategy, the site-specific conjugation to a single reduced cysteine in the C-terminal part of the R3VQ generates a well-defined bioconjugate in a high yield process. This new imaging probe is able to cross the BBB and label Aß deposits after intravenous injection. Also, it displays improved r1 and r2 relaxivities, up to 30 times higher than a widely used clinical contrast agent, and it allows MRI detection of amyloid deposits in post mortem brain tissue of a mouse model of AD. The ability to produce chemically-defined VHH conjugates that cross the BBB opens the way for future development of tailored imaging probes targeting intracerebral antigens.

A combination therapy of neural and glial restricted precursor cells and chronic quipazine treatment paired with passive cycling promotes quipazine-induced stepping in adult spinalized rats.

PubMed

Dugan, Elizabeth A; Shumsky, Jed S

2015-11-01

In order to develop optimal treatments to promote recovery from complete spinal cord injury (SCI), we examined the combination of: (1) a cellular graft of neural and glial restricted precursor (NRP/GRP) cells, (2) passive exercise, and (3) chronic quipazine treatment on behavioral outcomes and compared them with the individual treatment elements. NRP/GRP cells were transplanted at the time of spinalization. Daily passive exercise began 1 week after injury to give sufficient time for the animals to recover. Chronic quipazine administration began 2 weeks after spinalization to allow for sufficient receptor upregulation permitting the expression of its behavioral effects. Behavioral measures consisted of the Basso, Beattie, and Bresnahan (BBB) locomotor score and percent of weight-supported steps and hops on a treadmill. Rats displayed an increased response to quipazine (BBB ≥ 9) beginning at 8 weeks post-injury in all the animals that received the combination therapy. This increase in BBB score was persistent through the end of the study (12 weeks post-injury). Unlike the individual treatment groups which never achieved weight support, the combination therapy animals were able to perform uncoordinated weight-supported stepping without a body weight support system while on a moving treadmill (6.5 m per minute) and were capable of supporting their own weight in stance during open field locomotion testing. No regeneration of descending serotonergic projections into and through the lesion cavity was observed. Furthermore, these results are a testament to the capacity of the lumbar spinal cord, when properly stimulated, to sustain functioning locomotor circuitry following complete SCI.

Moderate traumatic brain injury increases the vulnerability to neurotoxicity induced by systemic administration of 6-hydroxydopamine in mice.

PubMed

de Oliveira, Paulo Alexandre; Ben, Juliana; Matheus, Filipe Carvalho; Schwarzbold, Marcelo Liborio; Moreira, Eduardo Luiz Gasnhar; Rial, Daniel; Walz, Roger; Prediger, Rui Daniel

2017-05-15

Moderate traumatic brain injury (TBI) might increase the vulnerability to neuronal neurodegeneration, but the basis of such selective neuronal susceptibility has remained elusive. In keeping with the disruption of the blood-brain barrier (BBB) caused by TBI, changes in BBB permeability following brain injury could facilitate the access of xenobiotics into the brain. To test this hypothesis, here we evaluated whether TBI would increase the susceptibility of nigrostriatal dopaminergic fibers to the systemic administration of 6-hydroxydopamine (6-OHDA), a classic neurotoxin used to trigger a PD-like phenotype in mice, but that in normal conditions is unable to cross the BBB. Adult Swiss mice were submitted to a moderate TBI using a free weight-drop device and, 5h later, they were injected intraperitoneally with a single dose of 6-OHDA (100mg/kg). Afterwards, during a period of 4weeks, the mice were submitted to a battery of behavioral tests, including the neurological severity score (NSS), the open field and the rotarod. Animals from the TBI plus 6-OHDA group displayed significant motor and neurological impairments that were improved by acute l-DOPA administration (25mg/kg, i.p.). Moreover, the observation of the motor deficits correlates with (i) a significant decrease in the tyrosine hydroxylase levels mainly in the rostral striatum and (ii) a significant increase in the levels of striatal glial fibrillary acidic protein (GFAP) levels. On the whole, the present findings demonstrate that a previous moderate TBI event increases the susceptibility to motor, neurological and neurochemical alterations induced by systemic administration of the dopaminergic neurotoxin 6-OHDA in mice. Copyright © 2017 Elsevier B.V. All rights reserved.

New frontiers in translational research in neuro-oncology and the blood-brain barrier: report of the tenth annual Blood-Brain Barrier Disruption Consortium Meeting.

PubMed

Doolittle, Nancy D; Abrey, Lauren E; Bleyer, W Archie; Brem, Steven; Davis, Thomas P; Dore-Duffy, Paula; Drewes, Lester R; Hall, Walter A; Hoffman, John M; Korfel, Agnieszka; Martuza, Robert; Muldoon, Leslie L; Peereboom, David; Peterson, Darryl R; Rabkin, Samuel D; Smith, Quentin; Stevens, Glen H J; Neuwelt, Edward A

2005-01-15

The blood-brain barrier (BBB) presents a major obstacle to the treatment of malignant brain tumors and other central nervous system (CNS) diseases. For this reason, a meeting partially funded by an NIH R13 grant was convened to discuss recent advances and future directions in translational research in neuro-oncology and the BBB. Cell biology and transport across the BBB, delivery of agents to the CNS, neuroimaging, angiogenesis, immunotherapy, and gene therapy, as well as glioma, primary CNS lymphoma, and metastases to the CNS were discussed. Transport across the BBB relates to the neurovascular unit, which consists not only of endothelial cells but also of pericyte, glia, and neuronal elements.

[Research of bornrol promote drugs through blood-brain barrier].

PubMed

Lv, Xuxiao; Sun, Mingjiang; Sun, Fengzhi

2012-04-01

Malignant tumor, epilepsy, dementia, cerebral ischemia and other brain diseases have very high rates of disability and mortality. Currently, many drugs are developed to treat such diseases and the effect is obviously. But they can not achieve the purpose to control these diseases because many of the drugs can not pass through the blood-brain barrier (BBB). Therefore, the treatment is not good. Borneol as the represent of the aromatic resuscitation medicine, it has strong fat-soluble active ingredients, small molecular weight, volatile and through the BBB quickly. It can also promote other therapeutic drugs through the BBB. It has two-ways regulations on BBB permeability and the damage of brain tissue is small, this have important theoretical significances and application values.

Potassium Aspartate Attenuates Brain Injury Induced by Controlled Cortical Impact in Rats Through Increasing Adenosine Triphosphate (ATP) Levels, Na+/K+-ATPase Activity and Reducing Brain Edema.

PubMed

Gu, Yi; Zhang, Jie; Zhao, Yumei; Su, Yujin; Zhang, Yazhuo

2016-12-13

BACKGROUND Potassium aspartate (PA), as an electrolyte supplement, is widely used in clinical practice. In our previous study, we found PA had neuroprotective effects against apoptosis after cerebral ischemia/reperfusion in rats. In this study, we examine whether PA has protective effects on traumatic brain injury (TBI). MATERIAL AND METHODS TBI was induced by controlled cortical impact (CCI) in rats. Vehicle treatment (control) or PA treatment was administered intraperitoneally at 30 minutes after CCI. The modified neurological severity score (mNSS) and cortical lesion volume were examined. Brain edema and blood-brain barrier (BBB) integrity were measured, as well as brain ATP contents, lactic acid levels, and Na+/K+-ATPase activities. RESULTS We found that CCI induced cortical injury in rats. Acute PA treatment at the dose of 62.5 mg/kg and 125 mg/kg significantly improved neurological deficits (p<0.05 and p<0.001, respectively) and decreased the cortical lesion volume (p<0.05 and p<0.001, respectively) compared with vehicle-only treatment. PA treatment at the dose of 125 mg/kg attenuated brain edema and ameliorated BBB integrity. In addition, PA treatment significantly reduced the loss of ATP (p<0.01), reduced lactic acid levels (p<0.001), and increased the activity of Na+/K+-ATPase (p<0.01). CONCLUSIONS Our results indicate PA has neuroprotective effects on TBI through increasing ATP levels, Na+/K+-ATPase activity, and reducing brain edema. It provides experimental evidence for the clinical application of PA.

Differential Adaptations of the Musculoskeletal System after Spinal Cord Contusion and Transection in Rats.

PubMed

Lin, Ching-Yi; Androjna, Charlie; Rozic, Richard; Nguyen, Bichtram; Parsons, Brett; Midura, Ronald J; Lee, Yu-Shang

2018-04-05

Spinal cord injury (SCI) causes impaired neuronal function with associated deficits in the musculoskeletal system, which can lead to permanent disability. Here, the impact of SCI on in vivo musculoskeletal adaptation was determined by studying deficits in locomotor function and analyzing changes that occur in the muscle and bone compartments within the rat hindlimb after contusion or transection SCI. Analyses of locomotor patterns, as assessed via the Basso, Beattie, and Bresnahan (BBB) rating scale, revealed that transection animals showed significant deficits, while the contusion group had moderate deficits, compared with naïve groups. Muscle myofiber cross-sectional areas (CSA) of both the soleus and tibialis anterior muscles were significantly decreased three months after contusion SCI. Such decreases in CSA were even more dramatic in the transection SCI group, suggesting a dependence on muscle activity, which is further validated by the correlation analyses between BBB score and myofiber CSA. Bone compartment analyses, however, revealed that transection animals showed the most significant deficits, while contusion animals showed no significant differences in the trabecular bone content within the proximal tibia compartment. In general, values of bone volume per total bone volume (BV/TV) were similar across the SCI groups. Significant decreases were observed, however, in the transection animals for bone mineral content, bone mineral density, and three-dimensional trabecular structure parameters (trabecular number, thickness, and spacing) compared with the naïve and contusion groups. Together, these findings suggest an altered musculoskeletal system can be correlated directly to motor dysfunctions seen after SCI.

Inhibition of 2-AG hydrolysis differentially regulates blood brain barrier permeability after injury.

PubMed

Piro, Justin R; Suidan, Georgette L; Quan, Jie; Pi, YeQing; O'Neill, Sharon M; Ilardi, Marissa; Pozdnyakov, Nikolay; Lanz, Thomas A; Xi, Hualin; Bell, Robert D; Samad, Tarek A

2018-05-14

Acute neurological insults caused by infection, systemic inflammation, ischemia, or traumatic injury are often associated with breakdown of the blood-brain barrier (BBB) followed by infiltration of peripheral immune cells, cytotoxic proteins, and water. BBB breakdown and extravasation of these peripheral components into the brain parenchyma result in inflammation, oxidative stress, edema, excitotoxicity, and neurodegeneration. These downstream consequences of BBB dysfunction can drive pathophysiological processes and play a substantial role in the morbidity and mortality of acute and chronic neurological insults, and contribute to long-term sequelae. Preserving or rescuing BBB integrity and homeostasis therefore represents a translational research area of high therapeutic potential. Induction of general and localized BBB disruption in mice was carried out using systemic administration of LPS and focal photothrombotic ischemic insult, respectively, in the presence and absence of the monoacylglycerol lipase (MAGL) inhibitor, CPD-4645. The effects of CPD-4645 treatment were assessed by gene expression analysis performed on neurovascular-enriched brain fractions, cytokine and inflammatory mediator measurement, and functional assessment of BBB permeability. The mechanism of action of CPD-4645 was studied pharmacologically using inverse agonists/antagonists of the cannabinoid receptors CB1 and CB2. Here, we demonstrate that the neurovasculature exhibits a unique transcriptional signature following inflammatory insults, and pharmacological inhibition of MAGL using a newly characterized inhibitor rescues the transcriptional profile of brain vasculature and restores its functional homeostasis. This pronounced effect of MAGL inhibition on blood-brain barrier permeability is evident following both systemic inflammatory and localized ischemic insults. Mechanistically, the protective effects of the MAGL inhibitor are partially mediated by cannabinoid receptor signaling in the ischemic brain insult. Our results support considering MAGL inhibitors as potential therapeutics for BBB dysfunction and cerebral edema associated with inflammatory brain insults.

Pericytes as Inducers of Rapid, Matrix Metalloproteinase-9-Dependent Capillary Damage during Ischemia

PubMed Central

Underly, Robert G.; Levy, Manuel; Hartmann, David A.; Grant, Roger I.; Watson, Ashley N.

2017-01-01

Blood–brain barrier disruption (BBB) and release of toxic blood molecules into the brain contributes to neuronal injury during stroke and other cerebrovascular diseases. While pericytes are builders and custodians of the BBB in the normal brain, their impact on BBB integrity during ischemia remains unclear. We imaged pericyte-labeled transgenic mice with in vivo two-photon microscopy to examine the relationship between pericytes and blood plasma leakage during photothrombotic occlusion of cortical capillaries. Upon cessation of capillary flow, we observed that plasma leakage occurred with three times greater frequency in regions where pericyte somata adjoined the endothelium. Pericyte somata covered only 7% of the total capillary length in cortex, indicating that a disproportionate amount of leakage occurred from a small fraction of the capillary bed. Plasma leakage was preceded by rapid activation of matrix metalloproteinase (MMP) at pericyte somata, which was visualized at high resolution in vivo using a fluorescent probe for matrix metalloproteinase-2/9 activity, fluorescein isothiocyanate (FITC)-gelatin. Coinjection of an MMP-9 inhibitor, but not an MMP-2 inhibitor, reduced pericyte-associated FITC-gelatin fluorescence and plasma leakage. These results suggest that pericytes contribute to rapid and localized proteolytic degradation of the BBB during cerebral ischemia. SIGNIFICANCE STATEMENT Pericytes are a key component of the neurovascular unit and are essential for normal BBB function. However, during acute ischemia, we find that pericytes are involved in creating rapid and heterogeneous BBB disruption in the capillary bed. The mechanism by which pericytes contribute to BBB damage warrants further investigation, as it may yield new therapeutic targets for acute stroke injury and other neurological diseases involving capillary flow impairment. PMID:28053036

Antidiabetic drugs restore abnormal transport of amyloid-β across the blood-brain barrier and memory impairment in db/db mice.

PubMed

Chen, Fang; Dong, Rong Rong; Zhong, Kai Long; Ghosh, Arijit; Tang, Su Su; Long, Yan; Hu, Mei; Miao, Ming Xing; Liao, Jian Min; Sun, Hong Bing; Kong, Ling Yi; Hong, Hao

2016-02-01

Previous studies have shown significant changes in amyloid-β (Aβ) transport across the blood-brain barrier (BBB) under diabetic conditions with hypoinsulinemia, which is involved in diabetes-associated cognitive impairment. Present study employed db/db mice with hyperinsulinemia to investigate changes in Aβ transport across the BBB, hippocampal synaptic plasticity, and restorative effects of antidiabetic drugs. Our results showed that db/db mice exhibited similar changes in Aβ transport across the BBB to that of insulin-deficient mice. Chronic treatment of db/db mice with antidiabetic drugs such as metformin, glibenclamide and insulin glargine significantly decreased Aβ influx across the BBB determined by intra-arterial infusion of (125)I-Aβ(1-40), and expression of the receptor for advanced glycation end products (RAGE) participating in Aβ influx. Insulin glargine, but not, metformin or glibenclamide increased Aβ efflux across the BBB determined by stereotaxic intra-cerebral infusion of (125)I-Aβ(1-40), and expression of the low-density lipoprotein receptor related protein 1 (LRP1) participating in Aβ efflux. Moreover, treatment with these drugs significantly decreased hippocampal Aβ(1-40) or Aβ(1-42) and inhibited neuronal apoptosis. The drugs also ameliorated memory impairment confirmed by improved performance on behavioral tasks. However, insulin glargine or glibenclamide, but not metformin, restored hippocampal synaptic plasticity characterized by enhancing in vivo long-term potentiation (LTP). Further study found that these three drugs significantly restrained NF-κB, but only insulin glargine enhanced peroxisome proliferator-activated receptor γ (PPARγ) activity at the BBB in db/db mice. Our data indicate that the antidiabetic drugs can partially restore abnormal Aβ transport across the BBB and memory impairment under diabetic context. Copyright © 2015 Elsevier Ltd. All rights reserved.

Establishment of a new conditionally immortalized cell line from human brain microvascular endothelial cells: a promising tool for human blood-brain barrier studies.

PubMed

Kamiichi, Atsuko; Furihata, Tomomi; Kishida, Satoshi; Ohta, Yuki; Saito, Kosuke; Kawamatsu, Shinya; Chiba, Kan

2012-12-07

The blood-brain barrier (BBB) is formed by brain microvascular endothelial cells (BMEC) working together with astrocytes and pericytes, in which tight junctions and various transporters strictly regulate the penetration of diverse compounds into the brain. Clarification of the molecular machinery that provides such regulation using in vitro BBB models has provided important insights into the roles of the BBB in central nervous system (CNS) disorders and CNS drug development. In this study, we succeeded in establishing a new cell line, hereinafter referred to as human BMEC/conditionally immortalized, clone β (HBMEC/ciβ), as part of our ongoing efforts to develop an in vitro human BBB model. Our results showed that HBMEC/ciβ proliferated well. Furthermore, we found that HBMEC/ciβ exhibited the barrier property of restricting small molecule intercellular penetration and possessed effective efflux transporter functions, both of which are essential to a functioning BBB. Because higher temperatures are known to terminate immortalization signals, we specifically examined the effects of higher temperatures on the HBMEC/ciβ differentiation status. The results showed that higher temperatures stimulated HBMEC/ciβ differentiation, marked by morphological alteration and increases in several mRNA levels. To summarize, our data indicates that the newly established HBMEC/ciβ offers a promising tool for use in the development of a practical in vitro human BBB model that could make significant contributions toward understanding the molecular biology of CNS disorders, as well as to CNS drug development. It is also believed that the development of a specific culture method for HBMEC/ciβ will add significant value to the HBMEC/ciβ-based BBB model. Copyright © 2012 Elsevier B.V. All rights reserved.

Wnt activation of immortalized brain endothelial cells as a tool for generating a standardized model of the blood brain barrier in vitro.

PubMed

Paolinelli, Roberta; Corada, Monica; Ferrarini, Luca; Devraj, Kavi; Artus, Cédric; Czupalla, Cathrin J; Rudini, Noemi; Maddaluno, Luigi; Papa, Eleanna; Engelhardt, Britta; Couraud, Pierre Olivier; Liebner, Stefan; Dejana, Elisabetta

2013-01-01

Reproducing the characteristics and the functional responses of the blood-brain barrier (BBB) in vitro represents an important task for the research community, and would be a critical biotechnological breakthrough. Pharmaceutical and biotechnology industries provide strong demand for inexpensive and easy-to-handle in vitro BBB models to screen novel drug candidates. Recently, it was shown that canonical Wnt signaling is responsible for the induction of the BBB properties in the neonatal brain microvasculature in vivo. In the present study, following on from earlier observations, we have developed a novel model of the BBB in vitro that may be suitable for large scale screening assays. This model is based on immortalized endothelial cell lines derived from murine and human brain, with no need for co-culture with astrocytes. To maintain the BBB endothelial cell properties, the cell lines are cultured in the presence of Wnt3a or drugs that stabilize β-catenin, or they are infected with a transcriptionally active form of β-catenin. Upon these treatments, the cell lines maintain expression of BBB-specific markers, which results in elevated transendothelial electrical resistance and reduced cell permeability. Importantly, these properties are retained for several passages in culture, and they can be reproduced and maintained in different laboratories over time. We conclude that the brain-derived endothelial cell lines that we have investigated gain their specialized characteristics upon activation of the canonical Wnt pathway. This model may be thus suitable to test the BBB permeability to chemicals or large molecular weight proteins, transmigration of inflammatory cells, treatments with cytokines, and genetic manipulation.

High-density lipoprotein-based therapy reduces the hemorrhagic complications associated with tissue plasminogen activator treatment in experimental stroke.

PubMed

Lapergue, Bertrand; Dang, Bao Quoc; Desilles, Jean-Philippe; Ortiz-Munoz, Guadalupe; Delbosc, Sandrine; Loyau, Stéphane; Louedec, Liliane; Couraud, Pierre-Olivier; Mazighi, Mikael; Michel, Jean-Baptiste; Meilhac, Olivier; Amarenco, Pierre

2013-03-01

We have previously reported that intravenous injection of high-density lipoproteins (HDLs) was neuroprotective in an embolic stroke model. We hypothesized that HDL vasculoprotective actions on the blood-brain barrier (BBB) may decrease hemorrhagic transformation-associated with tissue plasminogen activator (tPA) administration in acute stroke. We used tPA alone or in combination with HDLs in vivo in 2 models of focal middle cerebral artery occlusion (MCAO) (embolic and 4-hour monofilament MCAO) and in vitro in a model of BBB. Sprague-Dawley rats were submitted to MCAO, n=12 per group. The rats were then randomly injected with tPA (10 mg/kg) or saline with or without human plasma purified-HDL (10 mg/kg). The therapeutic effects of HDL and BBB integrity were assessed blindly 24 hours later. The integrity of the BBB was also tested using an in vitro model of human cerebral endothelial cells under oxygen-glucose deprivation. tPA-treated groups had significantly higher mortality and rate of hemorrhagic transformation at 24 hours in both MCAO models. Cotreatment with HDL significantly reduced stroke-induced mortality versus tPA alone (by 42% in filament MCAO, P=0.009; by 73% in embolic MCAO, P=0.05) and tPA-induced intracerebral parenchymal hematoma (by 92% in filament MCAO, by 100% in embolic MCAO; P<0.0001). This was consistent with an improved BBB integrity. In vitro, HDLs decreased oxygen-glucose deprivation-induced BBB permeability (P<0.05) and vascular endothelial cadherin disorganization. HDL injection decreased tPA-induced hemorrhagic transformation in rat models of MCAO. Both in vivo and in vitro results support the vasculoprotective action of HDLs on BBB under ischemic conditions.

Glycolysis-mediated control of blood-brain barrier development and function.

PubMed

Salmina, Alla B; Kuvacheva, Natalia V; Morgun, Andrey V; Komleva, Yulia K; Pozhilenkova, Elena A; Lopatina, Olga L; Gorina, Yana V; Taranushenko, Tatyana E; Petrova, Lyudmila L

2015-07-01

The blood-brain barrier (BBB) consists of differentiated cells integrating in one ensemble to control transport processes between the central nervous system (CNS) and peripheral blood. Molecular organization of BBB affects the extracellular content and cell metabolism in the CNS. Developmental aspects of BBB attract much attention in recent years, and barriergenesis is currently recognized as a very important and complex mechanism of CNS development and maturation. Metabolic control of angiogenesis/barriergenesis may be provided by glucose utilization within the neurovascular unit (NVU). The role of glycolysis in the brain has been reconsidered recently, and it is recognized now not only as a process active in hypoxic conditions, but also as a mechanism affecting signal transduction, synaptic activity, and brain development. There is growing evidence that glycolysis-derived metabolites, particularly, lactate, affect barriergenesis and functioning of BBB. In the brain, lactate produced in astrocytes or endothelial cells can be transported to the extracellular space via monocarboxylate transporters (MCTs), and may act on the adjoining cells via specific lactate receptors. Astrocytes are one of the major sources of lactate production in the brain and significantly contribute to the regulation of BBB development and functioning. Active glycolysis in astrocytes is required for effective support of neuronal activity and angiogenesis, while endothelial cells regulate bioavailability of lactate for brain cells adjusting its bidirectional transport through the BBB. In this article, we review the current knowledge with regard to energy production in endothelial and astroglial cells within the NVU. In addition, we describe lactate-driven mechanisms and action of alternative products of glucose metabolism affecting BBB structural and functional integrity in developing and mature brain. Copyright © 2015 Elsevier Ltd. All rights reserved.

Blood-brain barrier KCa3.1 channels: evidence for a role in brain Na uptake and edema in ischemic stroke.

PubMed

Chen, Yi-Je; Wallace, Breanna K; Yuen, Natalie; Jenkins, David P; Wulff, Heike; O'Donnell, Martha E

2015-01-01

KCa3.1, a calcium-activated potassium channel, regulates ion and fluid secretion in the lung and gastrointestinal tract. It is also expressed on vascular endothelium where it participates in blood pressure regulation. However, the expression and physiological role of KCa3.1 in blood-brain barrier (BBB) endothelium has not been investigated. BBB endothelial cells transport Na(+) and Cl(-) from the blood into the brain transcellularly through the co-operation of multiple cotransporters, exchangers, pumps, and channels. In the early stages of cerebral ischemia, when the BBB is intact, edema formation occurs by processes involving increased BBB transcellular Na(+) transport. This study evaluated whether KCa3.1 is expressed on and participates in BBB ion transport. The expression of KCa3.1 on cultured cerebral microvascular endothelial cells, isolated microvessels, and brain sections was evaluated by Western blot and immunohistochemistry. Activity of KCa3.1 on cerebral microvascular endothelial cells was examined by K(+) flux assays and patch-clamp. Magnetic resonance spectroscopy and MRI were used to measure brain Na(+) uptake and edema formation in rats with focal ischemic stroke after TRAM-34 treatment. KCa3.1 current and channel protein were identified on bovine cerebral microvascular endothelial cells and freshly isolated rat microvessels. In situ KCa3.1 expression on BBB endothelium was confirmed in rat and human brain sections. TRAM-34 treatment significantly reduced Na(+) uptake, and cytotoxic edema in the ischemic brain. BBB endothelial cells exhibit KCa3.1 protein and activity and pharmacological blockade of KCa3.1 seems to provide an effective therapeutic approach for reducing cerebral edema formation in the first 3 hours of ischemic stroke. © 2014 American Heart Association, Inc.

Pharmacokinetics of pericyte involvement in small-molecular drug transport across the blood-brain barrier.

PubMed

Mihajlica, Nebojsa; Betsholtz, Christer; Hammarlund-Udenaes, Margareta

2018-06-19

Pericytes are perivascular cells that play important roles in the regulation of the blood-brain barrier (BBB) properties. Pericyte-deficiency causes compromised BBB integrity and increase in permeability to different macromolecules mainly by upregulated transcytosis. The aim of the present study was to investigate pericyte involvement in the extent of small-molecular drug transport across the BBB. This was performed with five compounds: diazepam, digoxin, levofloxacin, oxycodone and paliperidone. Compounds were administered at low doses via subcutaneous injections as a cassette (simultaneously) to pericyte-deficient Pdgfb ret/ret mice and corresponding WT controls. Total drug partitioning across the BBB was calculated as the ratio of total drug exposures in brain tissue and plasma (K p,brain ). In addition, equilibrium dialysis experiments were performed to estimate unbound drug fractions in brain (f u,brain ) and plasma (f u,plasma ). This enabled estimation of unbound drug partitioning coefficients (K p,uu,brain ). The results indicated slight tendencies towards increase of total brain exposures in Pdgfb ret/ret mice as reflected in K p,brain values, which were within the 2-fold limit. Part of these differences could be explained by differences in plasma protein binding. No difference was found in brain tissue binding. The combined in vivo and in vitro data resulted in no differences in BBB transport in pericyte-deficiency, as described by similar K p,uu,brain values in Pdgfb ret/ret and control mice. In conclusion, these findings imply no influence of pericytes on the extent of BBB transport of small-molecular drugs, and suggest preserved BBB features relevant for handling of this type of molecules irrespective of pericyte presence at the brain endothelium. Copyright © 2018. Published by Elsevier B.V.

Blood-CSF-barrier dysfunction is a marker for encephalitic involvement in patients with aseptic meningitis/meningoencephalitis.

PubMed

Hoyer, C; Eisele, P; Ebert, A D; Schneider, S; Gass, A; Fatar, M; Szabo, K; Alonso, A

2016-11-01

The term "aseptic meningitis" encompasses cases of meningitis with negative bacterial CSF culture, which predominantly are of viral etiology. While the clinical course is usually benign, complications such as encephalitic involvement resulting in a more severe clinical course may occur. Dysfunction of the blood-brain-barrier (BBB), which is a prerequisite for viral entry into the brain parenchyma, can be approximated using the CSF/serum albumin ratio, readily obtainable in routine CSF analysis. Analysis of CSF patterns in patients with aseptic meningitis/meningoencephalitis with a focus on BBB dysfunction as a marker for encephalitic involvement. Retrospective chart review of patients admitted to our hospital between 2004 and 2016 with a diagnosis of aseptic meningitis/meningoencephalitis. Patients with aseptic meningitis displaying clinical, MR-tomographic or electroencephalographic signs of encephalitic involvement were significantly older than patients without these features (47.4 vs. 35.5 yrs., p=0.002). In patients with meningoencephalitis, CSF analysis revealed a more severe disruption of BBB, approximated by the CSF/serum albumin ratio (p=0.002). Compromised BBB function correlated positively with length of hospitalization (p=0.007), indicative of a more severe clinical course. The number of CSF lymphocytes was found to predict the severity of the BBB disruption, which additionally was more frequently observed when herpesviridae were identified as infectious agents. We suggest that the CSF/serum albumin ratio as an estimate for BBB function should be attended to in the evaluation of patients with aseptic meningitis. Severe BBB dysfunction, older age and infection with herpesviridae appear to raise the risk for encephalitic involvement. Copyright © 2016 Elsevier B.V. All rights reserved.

Nutraceutical agents with anti-inflammatory properties prevent dietary saturated-fat induced disturbances in blood-brain barrier function in wild-type mice.

PubMed

Takechi, Ryusuke; Pallebage-Gamarallage, Menuka M; Lam, Virginie; Giles, Corey; Mamo, John C

2013-06-19

Emerging evidence suggests that disturbances in the blood-brain barrier (BBB) may be pivotal to the pathogenesis and pathology of vascular-based neurodegenerative disorders. Studies suggest that heightened systemic and central inflammations are associated with BBB dysfunction. This study investigated the effect of the anti-inflammatory nutraceuticals garlic extract-aged (GEA), alpha lipoic acid (ALA), niacin, and nicotinamide (NA) in a murine dietary-induced model of BBB dysfunction. C57BL/6 mice were fed a diet enriched in saturated fatty acids (SFA, 40% fat of total energy) for nine months to induce systemic inflammation and BBB disturbances. Nutraceutical treatment groups included the provision of either GEA, ALA, niacin or NA in the positive control SFA-group and in low-fat fed controls. Brain parenchymal extravasation of plasma derived immunoglobulin G (IgG) and large macromolecules (apolipoprotein (apo) B lipoproteins) measured by quantitative immunofluorescent microscopy, were used as markers of disturbed BBB integrity. Parenchymal glial fibrillar acidic protein (GFAP) and cyclooxygenase-2 (COX-2) were considered in the context of surrogate markers of neurovascular inflammation and oxidative stress. Total anti-oxidant status and glutathione reductase activity were determined in plasma. Brain parenchymal abundance of IgG and apoB lipoproteins was markedly exaggerated in mice maintained on the SFA diet concomitant with significantly increased GFAP and COX-2, and reduced systemic anti-oxidative status. The nutraceutical GEA, ALA, niacin, and NA completely prevented the SFA-induced disturbances of BBB and normalized the measures of neurovascular inflammation and oxidative stress. The anti-inflammatory nutraceutical agents GEA, ALA, niacin, or NA are potent inhibitors of dietary fat-induced disturbances of BBB induced by systemic inflammations.

IMM-H004, A New Coumarin Derivative, Improved Focal Cerebral Ischemia via Blood-Brain Barrier Protection in Rats.

PubMed

Niu, Fei; Song, Xiu-Yun; Hu, Jin-Feng; Zuo, Wei; Kong, Ling-Lei; Wang, Xiao-Feng; Han, Ning; Chen, Nai-Hong

2017-10-01

IMM-H004 (7-hydroxy-5-methoxy-4-methyl-3-[4-methylpiperazin-1-yl]-2H-chromen-2-one) is a novel coumarin derivative that showed better effect in improving global cerebral ischemia in rats. However, the effects and mechanisms in focal cerebral ischemia were not clear. Blood-brain barrier (BBB) protection is a vital strategy for the treatment of cerebral ischemia. This study is to investigate whether IMM-H004 improves brain ischemia injury via BBB protection. Focal brain ischemia model was induced by middle cerebral artery occlusion for 1 hour and reperfusion (MCAO/R) for 24 hours in rats. IMM-H004 (1.5, 3, 6 mg/kg) and edaravone (positive drug, 6 mg/kg) were administered after 5 minutes of occlusion. Neurological score and TTC staining were used to evaluate the effect of IMM-H004. Evans Blue (EB) staining and electron microscopy were used to assess BBB permeability. Western blot, reverse transcription-polymerase chain reaction, and immunohistochemistry were used to detect the expression of BBB structure-related proteins. Compared with the model group, IMM-H004 in the focal brain ischemia model improved neurological function and reduced cerebral infarction size and edema content. IMM-H004 sharply reduced the EB content and alleviated BBB structure. In addition, IMM-H004 increased the level of zonula occludens (ZO-1) and occluding, decreased the level of aquaporin 4 and matrix metalloproteinase 9, either in cortex or in hippocampus. And all of these changed were related to BBB protection. IMM-H004 improved cerebral ischemia injury via BBB protection. For a potential therapy drug of cerebral ischemia, IMM-H004 merits further study. Copyright © 2017. Published by Elsevier Inc.

A Bayesian approach to in silico blood-brain barrier penetration modeling.

PubMed

Martins, Ines Filipa; Teixeira, Ana L; Pinheiro, Luis; Falcao, Andre O

2012-06-25

The human blood-brain barrier (BBB) is a membrane that protects the central nervous system (CNS) by restricting the passage of solutes. The development of any new drug must take into account its existence whether for designing new molecules that target components of the CNS or, on the other hand, to find new substances that should not penetrate the barrier. Several studies in the literature have attempted to predict BBB penetration, so far with limited success and few, if any, application to real world drug discovery and development programs. Part of the reason is due to the fact that only about 2% of small molecules can cross the BBB, and the available data sets are not representative of that reality, being generally biased with an over-representation of molecules that show an ability to permeate the BBB (BBB positives). To circumvent this limitation, the current study aims to devise and use a new approach based on Bayesian statistics, coupled with state-of-the-art machine learning methods to produce a robust model capable of being applied in real-world drug research scenarios. The data set used, gathered from the literature, totals 1970 curated molecules, one of the largest for similar studies. Random Forests and Support Vector Machines were tested in various configurations against several chemical descriptor set combinations. Models were tested in a 5-fold cross-validation process, and the best one tested over an independent validation set. The best fitted model produced an overall accuracy of 95%, with a mean square contingency coefficient (ϕ) of 0.74, and showing an overall capacity for predicting BBB positives of 83% and 96% for determining BBB negatives. This model was adapted into a Web based tool made available for the whole community at http://b3pp.lasige.di.fc.ul.pt.

Novel Antitransferrin Receptor Antibodies Improve the Blood-Brain Barrier Crossing Efficacy of Immunoliposomes.

PubMed

Gregori, Maria; Orlando, Antonina; Re, Francesca; Sesana, Silvia; Nardo, Luca; Salerno, Domenico; Mantegazza, Francesco; Salvati, Elisa; Zito, Andrea; Malavasi, Fabio; Masserini, Massimo; Cazzaniga, Emanuela

2016-01-01

Surface functionalization with antitransferrin receptor (TfR) mAbs has been suggested as the strategy to enhance the transfer of nanoparticles (NPs) across the blood-brain barrier (BBB) and to carry nonpermeant drugs from the blood into the brain. However, the efficiency of BBB crossing is currently too poor to be used in vivo. In the present investigation, we compared 6 different murine mAbs specific for different epitopes of the human TfR to identify the best performing one for the functionalization of NPs. For this purpose, we compared the ability of mAbs to cross an in vitro BBB model made of human brain capillary endothelial cells (hCMEC/D3). Liposomes functionalized with the best performing mAb (MYBE/4C1) were uptaken, crossed the BBB in vitro, and facilitated the BBB in vitro passage of doxorubicin, an anticancer drug, 3.9 folds more than liposomes functionalized with a nonspecific IgG, as assessed by confocal microscopy, radiochemical techniques, and fluorescence, and did not modify the cell monolayer structural or functional properties. These results show that MYBE/4C1 antihuman TfR mAb is a powerful resource for the enhancement of BBB crossing of NPs and is therefore potentially useful in the treatment of neurologic diseases and disorders including brain carcinomas. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Delivery of therapeutic peptides and proteins to the CNS.

PubMed

Salameh, Therese S; Banks, William A

2014-01-01

Peptides and proteins have potent effects on the brain after their peripheral administration, suggesting that they may be good substrates for the development of CNS therapeutics. Major hurdles to such development include their relation to the blood-brain barrier (BBB) and poor pharmacokinetics. Some peptides cross the BBB by transendothelial diffusion and others cross in the blood-to-brain direction by saturable transporters. Some regulatory proteins are also transported across the BBB and antibodies can enter the CNS via the extracellular pathways. Glycoproteins and some antibody fragments can be taken up and cross the BBB by mechanisms related to adsorptive endocytosis/transcytosis. Many peptides and proteins are transported out of the CNS by saturable efflux systems and enzymatic activity in the blood, CNS, or BBB are substantial barriers to others. Both influx and efflux transporters are altered by various substances and in disease states. Strategies that manipulate these interactions between the BBB and peptides and proteins provide many opportunities for the development of therapeutics. Such strategies include increasing transendothelial diffusion of small peptides, upregulation of saturable influx transporters with allosteric regulators and other posttranslational means, use of vectors and other Trojan horse strategies, inhibition of efflux transporters including with antisense molecules, and improvement in pharmacokinetic parameters to overcome short half-lives, tissue sequestration, and enzymatic degradation. © 2014 Elsevier Inc. All rights reserved.

Involvement of DMT1 +IRE in the transport of lead in an in vitro BBB model.

PubMed

Wang, Qiang; Luo, Wenjing; Zhang, Wenbin; Liu, Mingchao; Song, Haifeng; Chen, Jingyuan

2011-06-01

Homeostasis of the central nervous system (CNS) microenvironment is maintained by the blood-brain barrier (BBB). The BBB is particularly vulnerable to lead (Pb) insults. This study was designed to test the hypothesis that divalent metal transporter 1 (DMT1), which is a divalent cation membrane transporter, was involved in transcellular transport across the BBB. An in vitro BBB model, which was a co-culture system of human umbilical vascular endothelial cells (ECV304) and rat glioma cells (C6), was established. Transendothelial electrical resistance (TEER) and fluoresceinisothiocyanate (FITC)-dextran permeability results showed that Pb exposure at the tested concentrations had no significant effects on intercellular tightness. Pb transport displayed properties that were associated with iron response element (IRE) positive isoform of DMT1. Accordingly, Pb transport was significantly blocked by iron (Fe). Moreover, ECV304 cells that were depleted of Fe with the chelator deferoxamine (DFO) demonstrated increased Pb transport. By transfecting ECV-304 cells with a DMT1 expression vector, overexpression of DMT1 promoted an increase in Pb transport. Treatment of ECV304 cells with DMT1 antisense oligonucleotides (ASONs) MA1 significantly inhibited the transport of Pb. Our results suggest that Pb is transported in the in vitro BBB model by a transporter with biochemical properties similar to those of the DMT1 IRE-positive isoform. Copyright © 2009 Elsevier Ltd. All rights reserved.

Alternating magnetic field-induced hyperthermia increases iron oxide nanoparticle cell association/uptake and flux in blood-brain barrier models.

PubMed

Dan, Mo; Bae, Younsoo; Pittman, Thomas A; Yokel, Robert A

2015-05-01

Superparamagnetic iron oxide nanoparticles (IONPs) are being investigated for brain cancer therapy because alternating magnetic field (AMF) activates them to produce hyperthermia. For central nervous system applications, brain entry of diagnostic and therapeutic agents is usually essential. We hypothesized that AMF-induced hyperthermia significantly increases IONP blood-brain barrier (BBB) association/uptake and flux. Cross-linked nanoassemblies loaded with IONPs (CNA-IONPs) and conventional citrate-coated IONPs (citrate-IONPs) were synthesized and characterized in house. CNA-IONP and citrate-IONP BBB cell association/uptake and flux were studied using two BBB Transwell(®) models (bEnd.3 and MDCKII cells) after conventional and AMF-induced hyperthermia exposure. AMF-induced hyperthermia for 0.5 h did not alter CNA-IONP size but accelerated citrate-IONP agglomeration. AMF-induced hyperthermia for 0.5 h enhanced CNA-IONP and citrate-IONP BBB cell association/uptake. It also enhanced the flux of CNA-IONPs across the two in vitro BBB models compared to conventional hyperthermia and normothermia, in the absence of cell death. Citrate-IONP flux was not observed under these conditions. AMF-induced hyperthermia also significantly enhanced paracellular pathway flux. The mechanism appears to involve more than the increased temperature surrounding the CNA-IONPs. Hyperthermia induced by AMF activation of CNA-IONPs has potential to increase the BBB permeability of therapeutics for the diagnosis and therapy of various brain diseases.

The ameliorative effects of exercise on cognitive impairment and white matter injury from blood-brain barrier disruption induced by chronic cerebral hypoperfusion in adolescent rats.

PubMed

Lee, Jae-Min; Park, Jong-Min; Song, Min Kyung; Oh, Yoo Joung; Kim, Chang-Ju; Kim, Youn-Jung

2017-01-18

Vascular dementia is the progressive change in blood vessels that leads to neuronal injuries in vulnerable areas induced by chronic cerebral hypoperfusion (CCH). CCH induces disruption of blood-brain barrier (BBB), and this BBB disruption can initiate the cognitive impairment and white matter injury. In the present study, we evaluated the effect of treadmill exercise on the cognitive impairment, white matter injury, and BBB disruption induced by CCH. Vascular dementia was induced by permanent bilateral common carotid arteries occlusion (BCCAO) in rats. The rats in the exercise group were made to run on a treadmill for 30min once a day for 14 weeks, starting 4 weeks after birth. Our results revealed that treadmill exercise group was alleviated the cognitive impairment and myelin degradation induced by CCH. The disruption of BBB after CCH indicates degradation of occludin, zonula occluden-1 (ZO-1), and up-regulation of matrix metalloproteinases (MMPs). Treadmill exercise may provide protective effects on BBB disruption from degradation of occludin, ZO-1, and overexpression of MMP-9 after CCH. These findings suggest that treadmill exercise ameliorates cognitive impairment and white matter injury from BBB disruption induced by CCH in rats. The present study will be valuable for means of prophylactic and therapeutic intervention for patients with CCH. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Mustard-inspired delivery shuttle for enhanced blood-brain barrier penetration and effective drug delivery in glioma therapy.

PubMed

Wang, Nan; Sun, Pei; Lv, Mingming; Tong, Gangsheng; Jin, Xin; Zhu, Xinyuan

2017-05-02

Effective penetration through the blood-brain barrier (BBB) remains a challenge for the treatment of many brain diseases. In this study, a small molecule, sinapic acid (SA), extracted from mustard, was selected as a novel bioinspired BBB-permeable ligand for efficient drug delivery in glioma treatment. SA was conjugated on the surface of zwitterionic polymer poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-encapsulated bovine serum albumin (BSA)-based nanoparticles, yielding nBSA-SA. The PMPC shell serves as a protective layer to prolong the in vivo blood circulation time with a better chance to cross the BBB. Furthermore, temozolomide (TMZ), which can be loaded onto the nanoparticles via electrostatic interactions with acrylic acid (AA) to generate AA-nBSA-SA-TMZ, was applied as an excellent chemotherapeutic drug for glioma therapy. The obtained nanoparticles with a distinct size show great BBB permeability. Through the mechanism study, it was found that the cell internalization of the SA-conjugated nanoparticles is an energy-dependent process with only transient disruption of the BBB. The biological evaluation results unambiguously suggest that drug-loaded nanoparticles can lead to strong apoptosis on the tumor site and increase the median survival time of glioma-bearing mice. Overall, this novel BBB-permeable ligand SA paves the way for the delivery of cargo into the brain and provides a powerful nanoplatform for glioma therapy via intravenous administration.

Systemic delivery of blood-brain barrier-targeted polymeric nanoparticles enhances delivery to brain tissue.

PubMed

Saucier-Sawyer, Jennifer K; Deng, Yang; Seo, Young-Eun; Cheng, Christopher J; Zhang, Junwei; Quijano, Elias; Saltzman, W Mark

2015-01-01

Delivery of therapeutic agents to the central nervous system is a significant challenge, hindering progress in the treatment of diseases such as glioblastoma. Due to the presence of the blood-brain barrier (BBB), therapeutic agents do not readily transverse the brain endothelium to enter the parenchyma. Previous reports suggest that surface modification of polymer nanoparticles (NPs) can improve their ability to cross the BBB, but it is unclear whether the observed enhancements in transport are large enough to enhance therapy. In this study, we synthesized two degradable polymer NP systems surface-modified with ligands previously suggested to improve BBB transport, and tested their ability to cross the BBB after intravenous injection in mice. All the NP preparations were able to cross the BBB, although generally in low amounts (<0.5% of the injected dose), which was consistent with prior reports. One NP produced significantly higher brain uptake (∼0.8% of the injected dose): a block copolymer of polylactic acid and hyperbranched polyglycerol, surface modified with adenosine (PLA-HPG-Ad). PLA-HPG-Ad NPs provided controlled release of camptothecin, killing U87 glioma cells in culture. When administered intravenously in mice with intracranial U87 tumors, they failed to increase survival. These results suggest that enhancing NP transport across the BBB does not necessarily yield proportional pharmacological effects.

Detrimental role of the EP1 prostanoid receptor in blood-brain barrier damage following experimental ischemic stroke

PubMed Central

Frankowski, Jan C.; DeMars, Kelly M.; Ahmad, Abdullah S.; Hawkins, Kimberly E.; Yang, Changjun; Leclerc, Jenna L.; Doré, Sylvain; Candelario-Jalil, Eduardo

2015-01-01

Cyclooxygenase-2 (COX-2) is activated in response to ischemia and significantly contributes to the neuroinflammatory process. Accumulation of COX-2-derived prostaglandin E2 (PGE2) parallels the substantial increase in stroke-mediated blood-brain barrier (BBB) breakdown. Disruption of the BBB is a serious consequence of ischemic stroke, and is mainly mediated by matrix metalloproteinases (MMPs). This study aimed to investigate the role of PGE2 EP1 receptor in neurovascular injury in stroke. We hypothesized that pharmacological blockade or genetic deletion of EP1 protects against BBB damage and hemorrhagic transformation by decreasing the levels and activity of MMP-3 and MMP-9. We found that post-ischemic treatment with the EP1 antagonist, SC-51089, or EP1 genetic deletion results in a significant reduction in BBB disruption and reduced hemorrhagic transformation in an experimental model of transient focal cerebral ischemia. These neurovascular protective effects of EP1 inactivation are associated with a significant reduction in MMP-9/-3, less peripheral neutrophil infiltration, and a preservation of tight junction proteins (ZO-1 and occludin) composing the BBB. Our study identifies the EP1 signaling pathway as an important link between neuroinflammation and MMP-mediated BBB breakdown in ischemic stroke. Targeting the EP1 receptor could represent a novel approach to diminish the devastating consequences of stroke-induced neurovascular damage. PMID:26648273

Dynamic analysis of the blood-brain barrier disruption in experimental stroke using time domain in vivo fluorescence imaging.

PubMed

Abulrob, Abedelnasser; Brunette, Eric; Slinn, Jacqueline; Baumann, Ewa; Stanimirovic, Danica

2008-01-01

The blood-brain barrier (BBB) disruption following cerebral ischemia can be exploited to deliver imaging agents and therapeutics into the brain. The aim of this study was (a) to establish novel in vivo optical imaging methods for longitudinal assessment of the BBB disruption and (b) to assess size selectivity and temporal patterns of the BBB disruption after a transient focal ischemia. The BBB permeability was assessed using in vivo time domain near-infrared optical imaging after contrast enhancement with either free Cy5.5 (1 kDa) or Cy5.5 conjugated with bovine serum albumin (BSA) (67 kDa) in mice subjected to either 60- or 20-minute transient middle cerebral artery occlusion (MCAO) and various times of reperfusion (up to 14 days). In vivo imaging observations were corroborated by ex vivo brain imaging and microscopic analyses of fluorescent tracer extravasation. The in vivo optical contrast enhancement with Cy5.5 was spatially larger than that observed with BSA-Cy5.5. Longitudinal studies after a transient 20-minute MCAO suggested a bilateral BBB disruption, more pronounced in the ipsilateral hemisphere, peaking at day 7 and resolving at day 14 after ischemia. The area differential between the BBB disruption for small and large molecules could potentially be useful as a surrogate imaging marker for assessing perinfarct tissues to which neuroprotective therapies of appropriate sizes could be delivered.

Effects of Universal Mobile Telecommunications System (UMTS) electromagnetic fields on the blood-brain barrier in vitro.

PubMed

Franke, Helmut; Streckert, Joachim; Bitz, Andreas; Goeke, Johannes; Hansen, Volkert; Ringelstein, E Bernd; Nattkämper, Heiner; Galla, Hans-Joachim; Stögbauer, Florian

2005-09-01

The extensive use of mobile phone communication has raised public concerns about adverse health effects of radiofrequency (RF) electromagnetic fields (EMFs) in recent years. A central issue in this discussion is the question whether EMFs enhance the permeability of the blood-brain barrier (BBB). Here we report an investigation on the influence of a generic UMTS (Universal Mobile Telecommunications System) signal on barrier tightness, transport processes and the morphology of porcine brain microvascular endothelial cell cultures (PBEC) serving as an in vitro model of the BBB. An exposure device with integrated online monitoring system was developed for simultaneous exposure and measuring of transendothelial electrical resistance (TEER) to determine the tightness of the BBB. PBEC were exposed continuously for up to 84 h at an average electric-field strength of 3.4-34 V/m (maximum 1.8 W/kg) ensuring athermal conditions. We did not find any evidence of RF-field-induced disturbance of the function of the BBB. After and during exposure, the tightness of the BBB quantified by 14C-sucrose and serum albumin permeation as well as by TEER remained unchanged compared to sham-exposed cultures. Permeation of transporter substrates at the BBB as well as the localization and integrity of the tight-junction proteins occludin and ZO1 were not affected either.

Localized Down-regulation of P-glycoprotein by Focused Ultrasound and Microbubbles induced Blood-Brain Barrier Disruption in Rat Brain

NASA Astrophysics Data System (ADS)

Cho, Hongseok; Lee, Hwa-Youn; Han, Mun; Choi, Jong-Ryul; Ahn, Sanghyun; Lee, Taekwan; Chang, Yongmin; Park, Juyoung

2016-08-01

Multi-drug resistant efflux transporters found in Blood-Brain Barrier (BBB) acts as a functional barrier, by pumping out most of the drugs into the blood. Previous studies showed focused ultrasound (FUS) induced microbubble oscillation can disrupt the BBB by loosening the tight junctions in the brain endothelial cells; however, no study was performed to investigate its impact on the functional barrier of the BBB. In this study, the BBB in rat brains were disrupted using the MRI guided FUS and microbubbles. The immunofluorescence study evaluated the expression of the P-glycoprotein (P-gp), the most dominant multi-drug resistant protein found in the BBB. Intensity of the P-gp expression at the BBB disruption (BBBD) regions was significantly reduced (63.2 ± 18.4%) compared to the control area. The magnitude of the BBBD and the level of the P-gp down-regulation were significantly correlated. Both the immunofluorescence and histologic analysis at the BBBD regions revealed no apparent damage in the brain endothelial cells. The results demonstrate that the FUS and microbubbles can induce a localized down-regulation of P-gp expression in rat brain. The study suggests a clinically translation of this method to treat neural diseases through targeted delivery of the wide ranges of brain disorder related drugs.

Comparative study of expression and activity of glucose transporters between stem cell-derived brain microvascular endothelial cells and hCMEC/D3 cells.

PubMed

Al-Ahmad, Abraham J

2017-10-01

Glucose constitutes a major source of energy of mammalian brains. Glucose uptake at the blood-brain barrier (BBB) occurs through a facilitated glucose transport, through glucose transporter 1 (GLUT1), although other isoforms have been described at the BBB. Mutations in GLUT1 are associated with the GLUT1 deficiency syndrome, yet none of the current in vitro models of the human BBB maybe suited for modeling such a disorder. In this study, we investigated the expression of glucose transporters and glucose diffusion across brain microvascular endothelial cells (BMECs) derived from healthy patient-derived induced pluripotent stem cells (iPSCs). We investigated the expression of different glucose transporters at the BBB using immunocytochemistry and flow cytometry and measured glucose uptake and diffusion across BMEC monolayers obtained from two iPSC lines and from hCMEC/D3 cells. BMEC monolayers showed expression of several glucose transporters, in particular GLUT1, GLUT3, and GLUT4. Diffusion of glucose across the monolayers was mediated via a saturable transcellular mechanism and partially inhibited by pharmacological inhibitors. Taken together, our study suggests the presence of several glucose transporters isoforms at the human BBB and demonstrates the feasibility of modeling glucose across the BBB using patient-derived stem cells. Copyright © 2017 the American Physiological Society.

Establishment of a Human Blood-Brain Barrier Co-culture Model Mimicking the Neurovascular Unit Using Induced Pluri- and Multipotent Stem Cells.

PubMed

Appelt-Menzel, Antje; Cubukova, Alevtina; Günther, Katharina; Edenhofer, Frank; Piontek, Jörg; Krause, Gerd; Stüber, Tanja; Walles, Heike; Neuhaus, Winfried; Metzger, Marco

2017-04-11

In vitro models of the human blood-brain barrier (BBB) are highly desirable for drug development. This study aims to analyze a set of ten different BBB culture models based on primary cells, human induced pluripotent stem cells (hiPSCs), and multipotent fetal neural stem cells (fNSCs). We systematically investigated the impact of astrocytes, pericytes, and NSCs on hiPSC-derived BBB endothelial cell function and gene expression. The quadruple culture models, based on these four cell types, achieved BBB characteristics including transendothelial electrical resistance (TEER) up to 2,500 Ω cm 2 and distinct upregulation of typical BBB genes. A complex in vivo-like tight junction (TJ) network was detected by freeze-fracture and transmission electron microscopy. Treatment with claudin-specific TJ modulators caused TEER decrease, confirming the relevant role of claudin subtypes for paracellular tightness. Drug permeability tests with reference substances were performed and confirmed the suitability of the models for drug transport studies. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Characteristics of sequential targeting of brain glioma for transferrin-modified cisplatin liposome.

PubMed

Lv, Qing; Li, Li-Min; Han, Min; Tang, Xin-Jiang; Yao, Jin-Na; Ying, Xiao-Ying; Li, Fan-Zhu; Gao, Jian-Qing

2013-02-28

Methods on how to improve the sequential targeting of glioma subsequent to passing of drug through the blood-brain barrier (BBB) have been occasionally reported. However, the characteristics involved are poorly understood. In the present study, cisplatin (Cis) liposome (lipo) was modified with transferrin (Tf) to investigate the characteristics of potential sequential targeting to glioma. In bEnd3/C6 co-culture BBB models, higher transport efficiency across the BBB and cytotoxicity in basal C6 cells induced by Cis-lipo(Tf) than Cis-lipo and Cis-solution, suggest its sequential targeting effect. Interestingly, similar liposomal morphology as that of donor compartment was first demonstrated in the receptor solution of BBB models. Meanwhile, a greater acquisition in the lysosome of bEnd3, distributed sequentially into the nucleus of C6 cells were found for the Cis-lipo(Tf). Pre-incubation of chlorpromazine and Tf inhibited this process, indicating that a clathrin-dependent endocytosis is involved in the transport of Cis-lipo(Tf) across the BBB. Copyright © 2013 Elsevier B.V. All rights reserved.

Blood-Brain Barrier Disruption Caused by Ultrasound Bursts Combined with Microbubbles Depends on Anesthesia

NASA Astrophysics Data System (ADS)

McDannold, Nathan; Zhang, Yongzhi; Vykhodtseva, Natalia

2011-09-01

Prior works on BBB disruption via inter-arterial infusions of osmotic agents have shown a strong dependence on anesthesia. Here, we investigated whether different anesthesia agents can affect ultrasound-induced BBB disruption. A piston transducer fired through a rubber aperture (frequency: 532 kHz, diameter: 4 cm, aperture diameter: 16 mm) was used to generate the ultrasound fields, and sonications combined with an ultrasound contrast agent were performed at 5 power levels. BBB disruption was quantified by measuring the MRI contrast enhancement in T1-weighted MRI, and erythrocyte extravasation characterized in light microscopy. For each exposure level tested, experiments performed with ketamine/xylazine resulted in significantly greater (P<0.05) enhancement than with isoflurane/oxygen. The onset of severe red blood cell extravasation occurred at lower power levels with ketamine/xylazine. These results suggest ultrasound-induced BBB disruption can depend on anesthesia agent, possibly due effects on the vasculature. These results suggest that care is needed in comparing experiments with different anesthesia agents and physiological factors need to be considered with ultrasound-induced BBB disruption.

Astrocyte-derived VEGF-A drives blood-brain barrier disruption in CNS inflammatory disease.

PubMed

Argaw, Azeb Tadesse; Asp, Linnea; Zhang, Jingya; Navrazhina, Kristina; Pham, Trinh; Mariani, John N; Mahase, Sean; Dutta, Dipankar J; Seto, Jeremy; Kramer, Elisabeth G; Ferrara, Napoleone; Sofroniew, Michael V; John, Gareth R

2012-07-01

In inflammatory CNS conditions such as multiple sclerosis (MS), current options to treat clinical relapse are limited, and more selective agents are needed. Disruption of the blood-brain barrier (BBB) is an early feature of lesion formation that correlates with clinical exacerbation, leading to edema, excitotoxicity, and entry of serum proteins and inflammatory cells. Here, we identify astrocytic expression of VEGF-A as a key driver of BBB permeability in mice. Inactivation of astrocytic Vegfa expression reduced BBB breakdown, decreased lymphocyte infiltration and neuropathology in inflammatory and demyelinating lesions, and reduced paralysis in a mouse model of MS. Knockdown studies in CNS endothelium indicated activation of the downstream effector eNOS as the principal mechanism underlying the effects of VEGF-A on the BBB. Systemic administration of the selective eNOS inhibitor cavtratin in mice abrogated VEGF-A-induced BBB disruption and pathology and protected against neurologic deficit in the MS model system. Collectively, these data identify blockade of VEGF-A signaling as a protective strategy to treat inflammatory CNS disease.

Aspects on the Physiological and Biochemical Foundations of Neurocritical Care

PubMed Central

Nordström, Carl-Henrik; Koskinen, Lars-Owe; Olivecrona, Magnus

2017-01-01

Neurocritical care (NCC) is a branch of intensive care medicine characterized by specific physiological and biochemical monitoring techniques necessary for identifying cerebral adverse events and for evaluating specific therapies. Information is primarily obtained from physiological variables related to intracranial pressure (ICP) and cerebral blood flow (CBF) and from physiological and biochemical variables related to cerebral energy metabolism. Non-surgical therapies developed for treating increased ICP are based on knowledge regarding transport of water across the intact and injured blood–brain barrier (BBB) and the regulation of CBF. Brain volume is strictly controlled as the BBB permeability to crystalloids is very low restricting net transport of water across the capillary wall. Cerebral pressure autoregulation prevents changes in intracranial blood volume and intracapillary hydrostatic pressure at variations in arterial blood pressure. Information regarding cerebral oxidative metabolism is obtained from measurements of brain tissue oxygen tension (PbtO2) and biochemical data obtained from intracerebral microdialysis. As interstitial lactate/pyruvate (LP) ratio instantaneously reflects shifts in intracellular cytoplasmatic redox state, it is an important indicator of compromised cerebral oxidative metabolism. The combined information obtained from PbtO2, LP ratio, and the pattern of biochemical variables reveals whether impaired oxidative metabolism is due to insufficient perfusion (ischemia) or mitochondrial dysfunction. Intracerebral microdialysis and PbtO2 give information from a very small volume of tissue. Accordingly, clinical interpretation of the data must be based on information of the probe location in relation to focal brain damage. Attempts to evaluate global cerebral energy state from microdialysis of intraventricular fluid and from the LP ratio of the draining venous blood have recently been presented. To be of clinical relevance, the information from all monitoring techniques should be presented bedside online. Accordingly, in the future, the chemical variables obtained from microdialysis will probably be analyzed by biochemical sensors. PMID:28674514

Promising approaches to circumvent the blood-brain barrier: progress, pitfalls and clinical prospects in brain cancer

PubMed Central

Papademetriou, Iason T; Porter, Tyrone

2015-01-01

Brain drug delivery is a major challenge for therapy of central nervous system (CNS) diseases. Biochemical modifications of drugs or drug nanocarriers, methods of local delivery, and blood–brain barrier (BBB) disruption with focused ultrasound and microbubbles are promising approaches which enhance transport or bypass the BBB. These approaches are discussed in the context of brain cancer as an example in CNS drug development. Targeting to receptors enabling transport across the BBB offers noninvasive delivery of small molecule and biological cancer therapeutics. Local delivery methods enable high dose delivery while avoiding systemic exposure. BBB disruption with focused ultrasound and microbubbles offers local and noninvasive treatment. Clinical trials show the prospects of these technologies and point to challenges for the future. PMID:26488496

Promising approaches to circumvent the blood-brain barrier: progress, pitfalls and clinical prospects in brain cancer.

PubMed

Papademetriou, Iason T; Porter, Tyrone

2015-01-01

Brain drug delivery is a major challenge for therapy of central nervous system (CNS) diseases. Biochemical modifications of drugs or drug nanocarriers, methods of local delivery, and blood-brain barrier (BBB) disruption with focused ultrasound and microbubbles are promising approaches which enhance transport or bypass the BBB. These approaches are discussed in the context of brain cancer as an example in CNS drug development. Targeting to receptors enabling transport across the BBB offers noninvasive delivery of small molecule and biological cancer therapeutics. Local delivery methods enable high dose delivery while avoiding systemic exposure. BBB disruption with focused ultrasound and microbubbles offers local and noninvasive treatment. Clinical trials show the prospects of these technologies and point to challenges for the future.

Modeling the Blood-Brain Barrier in a 3D triple co-culture microfluidic system.

PubMed

Adriani, G; Ma, D; Pavesi, A; Goh, E L K; Kamm, R D

2015-01-01

The need for a blood-brain barrier (BBB) model that accurately mimics the physiological characteristics of the in-vivo situation is well-recognized by researchers in academia and industry. However, there is currently no in-vitro model allowing studies of neuronal growth and/or function influenced by factors from the blood that cross through the BBB. Therefore, we established a 3D triple co-culture microfluidic system using human umbilical vein endothelial cells (HUVEC) together with primary rat astrocytes and neurons. Immunostaining confirmed the successful triple co-culture system consisting of an intact BBB with tight intercellular junctions in the endothelial monolayer. The BBB selective permeability was determined by a fluorescent-based assay using dextrans of different molecular weights. Finally, neuron functionality was demonstrated by calcium imaging.

Roles of elevated 20‑HETE in the breakdown of blood brain barrier and the severity of brain edema in experimental traumatic brain injury.

PubMed

Lu, Liyan; Wang, Mingliang; Yuan, Fang; Wei, Xiaoer; Li, Wenbin

2018-05-01

Breakdown of the blood brain barrier (BBB) is a secondary injury following traumatic brain injury (TBI) and can lead to the development of brain edema. However, the factors that contribute to the disruption of the BBB and increase the severity of brain edema in TBI remain to be elucidated. 20‑hydroxyeicosatetraenoic acid (20‑HETE) is a metabolite of arachidonic acid. The inhibition of 20‑HETEsynthesis by HET0016 has been suggested as a strategy to decrease brain edema. The present study aimed to investigate whether the elevated production of 20‑HETE in cerebral tissue may contribute to BBB breakdown and increase the severity of brain edema in rats with TBI. BBB permeability was quantified using dynamic contrast‑enhanced magnetic resonance imaging and brain edema was measured according to brain water content. Superoxide production in injured tissue was also assessed. Liquid chromatography‑mass spectrometry was used to evaluate 20‑HETE production in injured tissue. Western blot analysis was used to assess the expression of occludin, zonula occludens (ZO)‑1, matrix metalloproteinase (MMP)‑9, and proteins of the c‑Jun N‑terminal kinase (JNK) pathway. A total of 3, 24 and 72 h following the induction of TBI, 20‑HETE levels, BBB permeability and brain edema were identified to be increased, accompanied by an increase in superoxide production. Conversely, superoxide dismutase levels, in addition to the total antioxidative capability were decreased. In addition, the expression of MMP‑9 and proteins of the JNK pathway was upregulated, whereas the expression of occludin and ZO‑1 was observed to be suppressed. These results suggested that 20‑HETE may aggravate BBB disruption following TBI, via enhancing the expression of MMP‑9 and tight junction proteins. Furthermore, oxidative stress and the JNK signaling pathway may be involved in BBB dysregulation. In conclusion, the results of the present demonstrated that the production of 20‑HETE was increased in cerebral tissue following traumatic injury, thus suggesting that it may contribute to the compromise of BBB integrity and the development of brain edema.

Simulating vasogenic brain edema using chronic VEGF infusion

PubMed Central

Piazza, Martin; Munasinghe, Jeeva; Murayi, Roger; Edwards, Nancy; Montgomery, Blake; Walbridge, Stuart; Merrill, Marsha; Chittiboina, Prashant

2017-01-01

OBJECTIVE To study peritumoral brain edema (PTBE), it is necessary to create a model that accurately simulates vasogenic brain edema (VBE) without introducing a complicated tumor environment. PTBE associated with brain tumors is predominantly a result of vascular endothelial growth factor (VEGF) secreted by brain tumors, and VEGF infusion alone can lead to histological blood-brain barrier (BBB) breakdown in the absence of tumor. VBE is intimately linked to BBB breakdown. The authors sought to establish a model for VBE with chronic infusion of VEGF that can be validated by serial in-vivo MRI and histological findings. METHODS Male Fischer rats (n = 182) underwent stereotactic striatal implantation of MRI-safe brain cannulas for chronic infusion of VEGF (2–20 μg/ml). Following a preinfusion phase (4–6 days), the rats were exposed to VEGF or control rat serum albumin (1.5 μl/hr) for as long as 144 hours. Serial MRI was performed during infusion on a high-field (9.4-T) machine at 12–24, 24–36, 48–72, and 120–144 hours. Rat brains were then collected and histological analysis was performed. RESULTS Control animals and animals infused with 2 μg/ml of VEGF experienced no neurological deficits, seizure activity, or abnormal behavior. Animals treated with VEGF demonstrated a significantly larger volume (42.90 ± 3.842 mm3) of T2 hyper-attenuation at 144 hours when compared with the volume (8.585 ± 1.664 mm3) in control animals (mean difference 34.31 ± 4.187 mm3, p < 0.0001, 95% CI 25.74–42.89 mm3). Postcontrast T1 enhancement in the juxtacanalicular region indicating BBB breakdown was observed in rats undergoing infusion with VEGF. At the later time periods (120–144 hrs) the volume of T1 enhancement (34.97 ± 8.99 mm3) was significantly less compared with the region of edema (p < 0.0001). Histologically, no evidence of necrosis or inflammation was observed with VEGF or control infusion. Immunohistochemical analysis demonstrated astrocyte activation, vascular remodeling, and increased claudin-5 expression in juxtacanalicular regions. Aquaporin-4 expression was increased in both control and VEGF animals in the juxtacanalicular regions. CONCLUSIONS The results of this study show that chronic brain infusion of VEGF creates a reliable model of VBE. This model lacks necrosis and inflammation that are characteristic of previous models of VBE. The model allows for a precise investigation into the mechanism of VBE formation. The authors also anticipate that this model will allow for investigation into the mechanism of glucocorticoid action in abrogating VBE, and to test novel therapeutic strategies targeting PTBE. PMID:28059647

Diverse action of lipoteichoic acid and lipopolysaccharide on neuroinflammation, blood-brain barrier disruption, and anxiety in mice.

PubMed

Mayerhofer, Raphaela; Fröhlich, Esther E; Reichmann, Florian; Farzi, Aitak; Kogelnik, Nora; Fröhlich, Eleonore; Sattler, Wolfgang; Holzer, Peter

2017-02-01

Microbial metabolites are known to affect immune system, brain, and behavior via activation of pattern recognition receptors such as Toll-like receptor 4 (TLR4). Unlike the effect of the TLR4 agonist lipopolysaccharide (LPS), the role of other TLR agonists in immune-brain communication is insufficiently understood. We therefore hypothesized that the TLR2 agonist lipoteichoic acid (LTA) causes immune activation in the periphery and brain, stimulates the hypothalamic-pituitary-adrenal (HPA) axis and has an adverse effect on blood-brain barrier (BBB) and emotional behavior. Since LTA preparations may be contaminated by LPS, an extract of LTA (LTA extract ), purified LTA (LTA pure ), and pure LPS (LPS ultrapure ) were compared with each other in their effects on molecular and behavioral parameters 3h after intraperitoneal (i.p.) injection to male C57BL/6N mice. The LTA extract (20mg/kg) induced anxiety-related behavior in the open field test, enhanced the circulating levels of particular cytokines and the cerebral expression of cytokine mRNA, and blunted the cerebral expression of tight junction protein mRNA. A dose of LPS ultrapure matching the amount of endotoxin/LPS contaminating the LTA extract reproduced several of the molecular and behavioral effects of LTA extract . LTA pure (20mg/kg) increased plasma levels of tumor necrosis factor-α (TNF-α), interleukin-6 and interferon-γ, and enhanced the transcription of TNF-α, interleukin-1β and other cytokines in the amygdala and prefrontal cortex. These neuroinflammatory effects of LTA pure were associated with transcriptional down-regulation of tight junction-associated proteins (claudin 5, occludin) in the brain. LTA pure also enhanced circulating corticosterone, but failed to alter locomotor and anxiety-related behavior in the open field test. These data disclose that TLR2 agonism by LTA causes peripheral immune activation and initiates neuroinflammatory processes in the brain that are associated with down-regulation of BBB components and activation of the HPA axis, although emotional behavior (anxiety) is not affected. The results obtained with an LTA preparation contaminated with LPS hint at a facilitatory interaction between TLR2 and TLR4, the adverse impact of which on long-term neuroinflammation, disruption of the BBB and mental health warrants further analysis. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Zinc ions regulate opening of tight junction favouring efflux of macromolecules via the GSK3β/snail-mediated pathway.

PubMed

Xiao, Ruyue; Yuan, Lan; He, Weijiang; Yang, Xiaoda

2018-01-24

Zinc is an essential trace element presenting in particularly high concentration in the brain. In some regions, e.g. lateral amygdala, subiculum and hippocampus, rapidly-exchangeable zinc may transiently reach even up to 600 μM. To explore the possible roles of high-concentration Zn 2+ in regulating the blood-brain barrier (BBB), we investigated the effects of Zn 2+ on the functions and structures of the tight junction (TJ) with an in vitro model of a Madin-Darby canine kidney (MDCK) cell monolayer. The experimental results indicated that high concentrations (>200 μM) of Zn 2+ can affect the TJ integrity in a polarized manner. Basolateral addition of Zn 2+ led to reversible TJ opening with pore paths of r ∼ 2 nm or more depending on Zn 2+ concentration. The efflux/influx ratios of different sized probes were found to be ∼4.6 for FD4 (M W 4000) and ∼1.8 for Eu-DTPA (M W 560), suggesting that the Zn 2+ -induced paracelluar channels favour efflux especially for macromolecules. Further mechanistic studies revealed that the elevated intracellular Zn 2+ taken from the basolateral side can increase phosphorylation of glycogen synthase kinase (GSK) 3β, primarily due to the inhibition of calcineurin (CaN), thus resulting in the elevation of the snail transcriptional repressors. Subsequently, Zn 2+ can cause the down-regulation of claudin-1, breakage of occludin and ZO-1 rings, and collapse of basolateral F-actin structures. These overall factors result in the formation of a trumpet-like paracellular channel, which allows asymmetric solute permeation. The ERK1/2 and JNK1/2 pathways may also be involved in the Zn 2+ -induced TJ opening process, while the activation of matrix metalloproteinase was not observed. Our results may suggest a potential role of zinc in regulation of BBB permeability associated with brain clearance of metabolites through the glymphatic system.

Physical insights into the blood-brain barrier translocation mechanisms

NASA Astrophysics Data System (ADS)

Theodorakis, Panagiotis E.; Müller, Erich A.; Craster, Richard V.; Matar, Omar K.

2017-08-01

The number of individuals suffering from diseases of the central nervous system (CNS) is growing with an aging population. While candidate drugs for many of these diseases are available, most of these pharmaceutical agents cannot reach the brain rendering most of the drug therapies that target the CNS inefficient. The reason is the blood-brain barrier (BBB), a complex and dynamic interface that controls the influx and efflux of substances through a number of different translocation mechanisms. Here, we present these mechanisms providing, also, the necessary background related to the morphology and various characteristics of the BBB. Moreover, we discuss various numerical and simulation approaches used to study the BBB, and possible future directions based on multi-scale methods. We anticipate that this review will motivate multi-disciplinary research on the BBB aiming at the design of effective drug therapies.

Live imaging using a FRET glucose sensor reveals glucose delivery to all cell types in the Drosophila brain.

PubMed

Volkenhoff, Anne; Hirrlinger, Johannes; Kappel, Johannes M; Klämbt, Christian; Schirmeier, Stefanie

2018-04-01

All complex nervous systems are metabolically separated from circulation by a blood-brain barrier (BBB) that prevents uncontrolled leakage of solutes into the brain. Thus, all metabolites needed to sustain energy homeostasis must be transported across this BBB. In invertebrates, such as Drosophila, the major carbohydrate in circulation is the disaccharide trehalose and specific trehalose transporters are expressed by the glial BBB. Here we analyzed whether glucose is able to contribute to energy homeostasis in Drosophila. To study glucose influx into the brain we utilized a genetically encoded, FRET-based glucose sensor expressed in a cell type specific manner. When confronted with glucose all brain cells take up glucose within two minutes. In order to characterize the glucose transporter involved, we studied Drosophila Glut1, the homologue of which is primarily expressed by the BBB-forming endothelial cells and astrocytes in the mammalian nervous system. In Drosophila, however, Glut1 is expressed in neurons and is not found at the BBB. Thus, Glut1 cannot contribute to initial glucose uptake from the hemolymph. To test whether gap junctional coupling between the BBB forming cells and other neural cells contributes to glucose distribution we assayed these junctions using RNAi experiments and only found a minor contribution of gap junctions to glucose metabolism. Our results provide the entry point to further dissect the mechanisms underlying glucose distribution and offer new opportunities to understand brain metabolism. Copyright © 2017 Elsevier Ltd. All rights reserved.

The transport of nifurtimox, an anti-trypanosomal drug, in an in vitro model of the human blood-brain barrier: evidence for involvement of breast cancer resistance protein.

PubMed

Watson, Christopher P; Dogruel, Murat; Mihoreanu, Larisa; Begley, David J; Weksler, Babette B; Couraud, Pierre O; Romero, Ignacio A; Thomas, Sarah A

2012-02-03

Human African trypanosomiasis (HAT) is a parasitic disease affecting sub-Saharan Africa. The parasites are able to traverse the blood-brain barrier (BBB), which marks stage 2 (S2) of the disease. Delivery of anti-parasitic drugs across the BBB is key to treating S2 effectively and the difficulty in achieving this goal is likely to be a reason why some drugs require highly intensive treatment regimes to be effective. This study aimed to investigate not only the drug transport mechanisms utilised by nifurtimox at the BBB, but also the impact of nifurtimox-eflornithine combination therapy (NECT) and other anti-HAT drug combination therapies (CTs) on radiolabelled-nifurtimox delivery in an in vitro model of drug accumulation and the human BBB, the hCMEC/D3 cell line. We found that nifurtimox appeared to use several membrane transporters, in particular breast-cancer resistance protein (BCRP), to exit the BBB cells. The addition of eflornithine caused no change in the accumulation of nifurtimox, nor did the addition of clinically relevant doses of the other anti-HAT drugs suramin, nifurtimox or melarsoprol, but a significant increase was observed with the addition of pentamidine. The results provide evidence that anti-HAT drugs are interacting with membrane transporters at the human BBB and suggest that combination with known transport inhibitors could potentially improve their efficacy. Copyright © 2011 Elsevier B.V. All rights reserved.

Additional increased effects of mannitol-temozolomide combined treatment on blood-brain barrier permeability.

PubMed

Choi, Chunggab; Kim, Hye Min; Shon, Jeeheun; Park, Jiae; Kim, Hyeong-Taek; Oh, Seung-Hun; Kim, Nam Keun; Kim, Ok Joon

2018-03-04

The blood-brain barrier (BBB) is major obstacle in drug or stem cell treatment in chronic stroke. We hypothesized that adding mannitol to temozolomide (TMZ) is a practically applicable method for resolving the low efficacy of intravenous mannitol therapy. In this study, we investigated whether BBB permeability could be increased by this combined treatment. First, we established a chronic ischemic stroke rat model and examined changes in leakage of Evans blue dye within a lesion site, and in expression of tight junction proteins (TJPs), by this combined treatment. Additionally, in an in vitro BBB model using trans-wells, we analyzed changes in diffusion of a fluorescent tracer and in expression of TJPs. Mannitol-TMZ combined treatment not only increased the amount of Evans blue dye within the stroke lesion site, but also reduced occludin expression in rat brain microvessels. The in vitro study also showed that combined treatment increased the permeability for two different-sized fluorescent tracers, especially large size, and decreased expression of TJPs, such as occludin and ZO-1. Increased BBB permeability effects were more prominent with combined than with single treatments. Mannitol-TMZ combined treatment induced a decrease of TJPs with a consequent increase in BBB permeability. This combined treatment is clinically useful and might provide new therapeutic options by enabling efficient intracerebral delivery of various drugs that could not otherwise be used to treat many CNS diseases due to their inability to penetrate the BBB. Copyright © 2018 Elsevier Inc. All rights reserved.

Whole-brain radiation fails to boost intracerebral gefitinib concentration in patients with brain metastatic non-small cell lung cancer: a self-controlled, pilot study.

PubMed

Fang, Luo; Sun, Xiaojiang; Song, Yu; Zhang, Yiwen; Li, Fanzhu; Xu, Yaping; Ma, Shenglin; Lin, Nengming

2015-10-01

Whole-brain radiation therapy (WBRT) is generally considered as an efficient strategy to improve blood-brain barrier (BBB) permeability by damaging BBB structure and is therefore, used as a promising pretreatment of chemotherapy. However, the impact of radiotherapy on leaky BBB is still controversial for the reason that BBB of metastatic brain tumor lesion had been breached by tumor metastasizing. Herein, we conducted a self-controlled study to evaluate the effect of WBRT on the permeability of BBB in non-small cell lung cancer (NSCLC) patients with brain metastases (BM). A prospective self-controlled research was performed. Radiation-naive NSCLC patients with BM were enrolled and treated with gefitinib for 2 weeks, and then concurrently combined with WBRT for 2 weeks. Plasma and cerebrospinal fluid (CSF) before and after WBRT were collected on day 15 and 29 after the initiation of gefitinib treatment. The concentrations of gefitinib in these samples were measured by HPLC. Three patients were enrolled and evaluated. The concentrations of gefitinib in plasma and CSF pre-WBRT were comparable to those of post-WBRT. Consequently, no significant change was noted in the CSF-to-plasma ratios of gefitinib before and after WBRT (2.79 ± 1.47 vs. 2.35 ± 1.74 %, p = 0.123). The WBRT may not affect the BBB permeability by determining the concentration of gefitinib in NSCLC patients with BM.

Blood-brain barrier integrity, intrathecal immunoactivation, and neuronal injury in HIV.

PubMed

Anesten, Birgitta; Yilmaz, Aylin; Hagberg, Lars; Zetterberg, Henrik; Nilsson, Staffan; Brew, Bruce J; Fuchs, Dietmar; Price, Richard W; Gisslén, Magnus

2016-12-01

Although blood-brain barrier (BBB) impairment has been reported in HIV-infected individuals, characterization of this impairment has not been clearly defined. BBB integrity was measured by CSF/plasma albumin ratio in this cross-sectional study of 631 HIV-infected individuals and 71 controls. We also analyzed CSF and blood HIV RNA and neopterin, CSF leukocyte count, and neurofilament light chain protein (NFL) concentrations. The HIV-infected participants included untreated neuroasymptomatic patients, patients with untreated HIV-associated dementia (HAD), and participants on suppressive antiretroviral treatment (ART). The albumin ratio was significantly increased in patients with HAD compared to all other groups. There were no significant differences between untreated neuroasymptomatic participants, treated participants, and controls. BBB integrity, however, correlated significantly with CSF leukocyte count, CSF HIV RNA, serum and CSF neopterin, and age in untreated neuroasymptomatic participants. In a multiple linear regression analysis, age, CSF neopterin, and CSF leukocyte count stood out as independent predictors of albumin ratio. A significant correlation was found between albumin ratio and CSF NFL in untreated neuroasymptomatic patients and in participants on ART. Albumin ratio, age, and CD4 cell count were confirmed as independent predictors of CSF NFL in multivariable analysis. BBB disruption was mainly found in patients with HAD, where BBB damage correlated with CNS immunoactivation. Albumin ratios also correlated with CSF inflammatory markers and NFL in untreated neuroasymptomatic participants. These findings give support to the association among BBB deterioration, intrathecal immunoactivation, and neuronal injury in untreated neuroasymptomatic HIV-infected individuals.

Validation of an immortalized human (hBMEC) in vitro blood-brain barrier model.

PubMed

Eigenmann, Daniela Elisabeth; Jähne, Evelyn Andrea; Smieško, Martin; Hamburger, Matthias; Oufir, Mouhssin

2016-03-01

We recently established and optimized an immortalized human in vitro blood-brain barrier (BBB) model based on the hBMEC cell line. In the present work, we validated this mono-culture 24-well model with a representative series of drug substances which are known to cross or not to cross the BBB. For each individual compound, a quantitative UHPLC-MS/MS method in Ringer HEPES buffer was developed and validated according to current regulatory guidelines, with respect to selectivity, precision, and reliability. Various biological and analytical challenges were met during method validation, highlighting the importance of careful method development. The positive controls antipyrine, caffeine, diazepam, and propranolol showed mean endothelial permeability coefficients (P e) in the range of 17-70 × 10(-6) cm/s, indicating moderate to high BBB permeability when compared to the barrier integrity marker sodium fluorescein (mean P e 3-5 × 10(-6) cm/s). The negative controls atenolol, cimetidine, and vinblastine showed mean P e values < 10 × 10(-6) cm/s, suggesting low permeability. In silico calculations were in agreement with in vitro data. With the exception of quinidine (P-glycoprotein inhibitor and substrate), BBB permeability of all control compounds was correctly predicted by this new, easy, and fast to set up human in vitro BBB model. Addition of retinoic acid and puromycin did not increase transendothelial electrical resistance (TEER) values of the BBB model.

Recreating blood-brain barrier physiology and structure on chip: A novel neurovascular microfluidic bioreactor.

PubMed

Brown, Jacquelyn A; Pensabene, Virginia; Markov, Dmitry A; Allwardt, Vanessa; Neely, M Diana; Shi, Mingjian; Britt, Clayton M; Hoilett, Orlando S; Yang, Qing; Brewer, Bryson M; Samson, Philip C; McCawley, Lisa J; May, James M; Webb, Donna J; Li, Deyu; Bowman, Aaron B; Reiserer, Ronald S; Wikswo, John P

2015-09-01

The blood-brain barrier (BBB) is a critical structure that serves as the gatekeeper between the central nervous system and the rest of the body. It is the responsibility of the BBB to facilitate the entry of required nutrients into the brain and to exclude potentially harmful compounds; however, this complex structure has remained difficult to model faithfully in vitro. Accurate in vitro models are necessary for understanding how the BBB forms and functions, as well as for evaluating drug and toxin penetration across the barrier. Many previous models have failed to support all the cell types involved in the BBB formation and/or lacked the flow-created shear forces needed for mature tight junction formation. To address these issues and to help establish a more faithful in vitro model of the BBB, we have designed and fabricated a microfluidic device that is comprised of both a vascular chamber and a brain chamber separated by a porous membrane. This design allows for cell-to-cell communication between endothelial cells, astrocytes, and pericytes and independent perfusion of both compartments separated by the membrane. This NeuroVascular Unit (NVU) represents approximately one-millionth of the human brain, and hence, has sufficient cell mass to support a breadth of analytical measurements. The NVU has been validated with both fluorescein isothiocyanate (FITC)-dextran diffusion and transendothelial electrical resistance. The NVU has enabled in vitro modeling of the BBB using all human cell types and sampling effluent from both sides of the barrier.

Development of the blood-brain barrier: a historical point of view.

PubMed

Ribatti, Domenico; Nico, Beatrice; Crivellato, Enrico; Artico, Marco

2006-01-01

Although there has been considerable controversy since the observation by Ehrlich more than 100 years ago that the brain did not take up dyes from the vascular system, the concept of an endothelial blood-brain barrier (BBB) was confirmed by the unequivocal demonstration that the passage of molecules from blood to brain and vice versa was prevented by endothelial tight junctions (TJs). There are three major functions implicated in the term "BBB": protection of the brain from the blood milieu, selective transport, and metabolism or modification of blood- or brain-borne substances. The BBB phenotype develops under the influence of associated brain cells, especially astrocytic glia, and consists of complex TJs and a number of specific transport and enzyme systems that regulate molecular traffic across the endothelial cells. The development of the BBB is a complex process that leads to endothelial cells with unique permeability characteristics due to high electrical resistance and the expression of specific transporters and metabolic pathways. This review article summarizes the historical background underlying our current knowledge of the cellular and molecular mechanisms involved in the development and maintenance of the BBB. (c) 2006 Wiley-Liss, Inc.

Temporal and Spatial Effects of Blast Overpressure on Blood-Brain Barrier Permeability in Traumatic Brain Injury.

PubMed

Kuriakose, Matthew; Rama Rao, Kakulavarapu V; Younger, Daniel; Chandra, Namas

2018-06-06

Blast-induced traumatic brain injury (bTBI) is a "signature wound" in soldiers during training and in combat and has also become a major cause of morbidity in civilians due to increased insurgency. This work examines the role of blood-brain barrier (BBB) disruption as a result of both primary biomechanical and secondary biochemical injury mechanisms in bTBI. Extravasation of sodium fluorescein (NaF) and Evans blue (EB) tracers were used to demonstrate that compromise of the BBB occurs immediately following shock loading, increases in intensity up to 4 hours and returns back to normal in 24 hours. This BBB compromise occurs in multiple regions of the brain in the anterior-posterior direction of the shock wave, with maximum extravasation seen in the frontal cortex. Compromise of the BBB is confirmed by (a) extravasation of tracers into the brain, (b) quantification of tight-junction proteins (TJPs) in the brain and the blood, and (c) tracking specific blood-borne molecules into the brain and brain-specific proteins into the blood. Taken together, this work demonstrates that the BBB compromise occurs as a part of initial biomechanical loading and is a function of increasing blast overpressures.

Role of the blood-brain barrier in multiple sclerosis.

PubMed

Ortiz, Genaro Gabriel; Pacheco-Moisés, Fermín Paul; Macías-Islas, Miguel Ángel; Flores-Alvarado, Luis Javier; Mireles-Ramírez, Mario A; González-Renovato, Erika Daniela; Hernández-Navarro, Vanessa Elizabeth; Sánchez-López, Angélica Lizeth; Alatorre-Jiménez, Moisés Alejandro

2014-11-01

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system associated with demyelination and axonal loss eventually leading to neurodegeneration. MS exhibits many of the hallmarks of an inflammatory autoimmune disorder including breakdown of the blood-brain barrier (BBB). The BBB is a complex organization of cerebral endothelial cells, pericytes and their basal lamina, which are surrounded and supported by astrocytes and perivascular macrophages. In pathological conditions, lymphocytes activated in the periphery infiltrate the central nervous system to trigger a local immune response that ultimately damages myelin and axons. Cytotoxic factors including pro-inflammatory cytokines, proteases, and reactive oxygen and nitrogen species accumulate and may contribute to myelin destruction. Dysregulation of the BBB and transendothelial migration of activated leukocytes are among the earliest cerebrovascular abnormalities seen in MS brains and parallel the release of inflammatory cytokines. In this review we establish the importance of the role of the BBB in MS. Improvements in our understanding of molecular mechanism of BBB functioning in physiological and pathological conditions could lead to improvement in the quality of life of MS patients. Copyright © 2015 IMSS. Published by Elsevier Inc. All rights reserved.

Regeneration of neurosecretory axons into various types of intrahypothalamic graft is promoted by the absence of the blood-brain barrier: a neurophysin-immunohistochemical and horseradish peroxidase-histochemical study.

PubMed

Ouassat, M; Dellmann, H D

1997-01-15

In order to test the hypothesis that neurosecretory axon regeneration occurs only in the presence of specific vascular, perivascular, and glial microenvironments, isografts of neural lobe and optic nerve and autografts of sciatic nerve were transplanted into the hypothalamo-neurohypophysial tract at the lateral retrochiasmatic area of adult male rats. The integrity of the blood-brain barrier (BBB) to intravenously administered horseradish peroxidase (HRP), the regenerative process of neurosecretory axons, and functional recovery from lesion-induced diabetes insipidus were analyzed at 18 hr, 36 hr, 10 days, 30 days, and 80 days postsurgery. Neurophysin-positive axons invaded all grafts, as well as perivascular spaces of the adjacent hypothalamus. Wherever neurosecretory axon regeneration occurred, the BBB was breached. Reestablishment of the BBB was paralleled by a decrease in both density and staining intensity of regenerated neurophysin-positive axons. These observations illustrate that neurosecretory axon regeneration is tributary of the absence of BBB. It is speculated that blood-borne factors, provided when the BBB is breached, initiate and sustain neurosecretory axon regeneration. In addition, products of glial elements may enhance or complement the above stimulatory processes.

Sleep Restriction Impairs Blood–Brain Barrier Function

PubMed Central

He, Junyun; Hsuchou, Hung; He, Yi; Kastin, Abba J.; Wang, Yuping

2014-01-01

The blood–brain barrier (BBB) is a large regulatory and exchange interface between the brain and peripheral circulation. We propose that changes of the BBB contribute to many pathophysiological processes in the brain of subjects with chronic sleep restriction (CSR). To achieve CSR that mimics a common pattern of human sleep loss, we quantified a new procedure of sleep disruption in mice by a week of consecutive sleep recording. We then tested the hypothesis that CSR compromises microvascular function. CSR not only diminished endothelial and inducible nitric oxide synthase, endothelin1, and glucose transporter expression in cerebral microvessels of the BBB, but it also decreased 2-deoxy-glucose uptake by the brain. The expression of several tight junction proteins also was decreased, whereas the level of cyclooxygenase-2 increased. This coincided with an increase of paracellular permeability of the BBB to the small tracers sodium fluorescein and biotin. CSR for 6 d was sufficient to impair BBB structure and function, although the increase of paracellular permeability returned to baseline after 24 h of recovery sleep. This merits attention not only in neuroscience research but also in public health policy and clinical practice. PMID:25355222

Sleep restriction impairs blood-brain barrier function.

PubMed

He, Junyun; Hsuchou, Hung; He, Yi; Kastin, Abba J; Wang, Yuping; Pan, Weihong

2014-10-29

The blood-brain barrier (BBB) is a large regulatory and exchange interface between the brain and peripheral circulation. We propose that changes of the BBB contribute to many pathophysiological processes in the brain of subjects with chronic sleep restriction (CSR). To achieve CSR that mimics a common pattern of human sleep loss, we quantified a new procedure of sleep disruption in mice by a week of consecutive sleep recording. We then tested the hypothesis that CSR compromises microvascular function. CSR not only diminished endothelial and inducible nitric oxide synthase, endothelin1, and glucose transporter expression in cerebral microvessels of the BBB, but it also decreased 2-deoxy-glucose uptake by the brain. The expression of several tight junction proteins also was decreased, whereas the level of cyclooxygenase-2 increased. This coincided with an increase of paracellular permeability of the BBB to the small tracers sodium fluorescein and biotin. CSR for 6 d was sufficient to impair BBB structure and function, although the increase of paracellular permeability returned to baseline after 24 h of recovery sleep. This merits attention not only in neuroscience research but also in public health policy and clinical practice. Copyright © 2014 the authors 0270-6474/14/3414697-10$15.00/0.

β-cyclodextrin-poly(β-amino ester) nanoparticles for sustained drug delivery across the blood-brain barrier.

PubMed

Gil, Eun Seok; Wu, Linfeng; Xu, Lichong; Lowe, Tao Lu

2012-11-12

Novel biodegradable polymeric nanoparticles composed of β-cyclodextrin and poly(β-amino ester) segments have been developed for sustained drug delivery across the blood-brain barrier (BBB). The nanoparticles have been synthesized by cross-linking β-cyclodextrin with poly(β-amino ester) via the Michael addition method. The chemical, physical, and degradation properties of the nanoparticles have been characterized by matrix-assisted laser desoption/ionization time-of-flight, attenuated total reflectance Fourier transform infrared spectroscopy, nuclear magnetic resonance, dynamic light scattering, and atomic force microscopy techniques. Bovine and human brain microvascular endothelial cell monolayers have been constructed as in vitro BBB models. Preliminary results show that the nanoparticles do not affect the integrity of the in vitro BBB models, and the nanoparticles have much higher permeability than dextran control across the in vitro BBB models. Doxorubicin has been loaded into the nanoparticles with a loading efficiency of 86%, and can be released from the nanoparticles for at least one month. The developed β-cyclodextrin-poly(β-amino ester) nanoparticles might be useful as drug carriers for transporting drugs across the BBB to treat chronic diseases in the brain.

Evaluation of a New Cardiac Pacemaker

ClinicalTrials.gov

2013-06-25

Atrial Fibrillation With 2 or 3° AV or Bifascicular Bundle Branch (BBB) Block; Normal Sinus Rhythm With 2 or 3° AV or BBB Block; Sinus Bradycardia With Infrequent Pauses or Unexplained Syncope With EP Findings

Micro-SPECT/CT-based pharmacokinetic analysis of 99mTc-diethylenetriaminepentaacetic acid in rats with blood-brain barrier disruption induced by focused ultrasound.

PubMed

Yang, Feng-Yi; Wang, Hsin-Ell; Lin, Guan-Liang; Teng, Ming-Che; Lin, Hui-Hsien; Wong, Tai-Tong; Liu, Ren-Shyan

2011-03-01

This study evaluated the pharmacokinetics of (99m)Tc-diethylenetriamine pentaacetate acid ((99m)Tc-DTPA) after intravenous administration in healthy and F98 glioma-bearing F344 rats in the presence of blood-brain barrier disruption (BBB-D) induced by focused ultrasound (FUS). The pharmacokinetics of the healthy and tumor-containing brains after BBB-D were compared to identify the optimal time period for combined treatment. Healthy and F98 glioma-bearing rats were injected intravenously with Evans blue (EB) and (99m)Tc-DTPA; these treatments took place with or without BBB-D induced by transcranial FUS of 1 hemisphere of the brain. The permeability of the BBB was quantified by EB extravasation. Twelve rats were scanned for 2 h to estimate uptake of (99m)Tc radioactivity with respect to time for the pharmacokinetic analysis. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining was performed to examine tissue damage. The accumulations of EB and (99m)Tc-DTPA in normal brains or brains with a tumor were significantly elevated after the intravenous injection when BBB-D was induced. The disruption-to-nondisruption ratio of the brains and the tumor-to-ipsilateral brain ratio of the tumors in terms of radioactivity reached a peak at 45 and 60 min, respectively. EB injection followed by sonication showed that there was an increase of about 2-fold in the tumor-to-ipsilateral brain EB ratio of the target tumors (7.36), compared with the control tumors (3.73). TUNEL staining showed no significant differences between the sonicated tumors and control tumors. This study demonstrates that (99m)Tc-DTPA micro-SPECT/CT can be used for the pharmacokinetic analysis of BBB-D induced by FUS. This method should be able to provide important information that will help with establishing an optimal treatment protocol for drug administration after FUS-induced BBB-D in clinical brain disease therapy.

Dietary Docosahexaenoic Acid Supplementation Enhances Expression of Fatty Acid-Binding Protein 5 at the Blood-Brain Barrier and Brain Docosahexaenoic Acid Levels.

PubMed

Pan, Yijun; Morris, Elonie R; Scanlon, Martin J; Marriott, Philip J; Porter, Christopher Jh; Nicolazzo, Joseph A

2018-03-27

The cytoplasmic trafficking of docosahexaenoic acid (DHA), a cognitively-beneficial fatty acid, across the blood-brain barrier (BBB) is governed by fatty acid-binding protein 5 (FABP5). Lower levels of brain DHA have been observed in Alzheimer's disease (AD), which is associated with diminished BBB expression of FABP5. Therefore, upregulating FABP5 expression at the BBB may be a novel approach for enhancing BBB transport of DHA in AD. DHA supplementation has been shown to be beneficial in various mouse models of AD, and therefore, the aim of this study was to determine whether DHA has the potential to upregulate the BBB expression of FABP5, thereby enhancing its own uptake into the brain. Treating human brain microvascular brain endothelial (hCMEC/D3) cells with the maximum tolerable concentration of DHA (12.5 μM) for 72 hr resulted in a 1.4-fold increase in FABP5 protein expression. Associated with this was increased expression of fatty acid transport proteins 1 and 4. To study the impact of dietary DHA supplementation, 6-8 week old C57BL/6 mice were fed with a control diet or a DHA-enriched diet for 21 days. Brain microvascular FABP5 protein expression was upregulated 1.7-fold in mice fed the DHA-enriched diet, and this was associated with increased brain DHA levels (1.3-fold). Despite an increase in brain DHA levels, reduced BBB transport of 14 C-DHA was observed over a 1 min perfusion, possibly as a result of competitive binding to FABP5 between dietary DHA and 14 C-DHA. The current study has demonstrated that DHA can increase BBB expression of FABP5, as well as fatty acid transporters, overall increasing brain DHA levels. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Prediction of Blood-Brain Barrier Disruption and Intracerebral Hemorrhagic Infarction Using Arterial Spin-Labeling Magnetic Resonance Imaging.

PubMed

Niibo, Takeya; Ohta, Hajime; Miyata, Shirou; Ikushima, Ichiro; Yonenaga, Kazuchika; Takeshima, Hideo

2017-01-01

Arterial spin-labeling magnetic resonance imaging is sensitive for detecting hyperemic lesions (HLs) in patients with acute ischemic stroke. We evaluated whether HLs could predict blood-brain barrier (BBB) disruption and hemorrhagic transformation (HT) in acute ischemic stroke patients. In a retrospective study, arterial spin-labeling was performed within 6 hours of symptom onset before revascularization treatment in 25 patients with anterior circulation large vessel occlusion on baseline magnetic resonance angiography. All patients underwent angiographic procedures intended for endovascular therapy and a noncontrast computed tomography scan immediately after treatment. BBB disruption was defined as a hyperdense lesion present on the posttreatment computed tomography scan. A subacute magnetic resonance imaging or computed tomography scan was performed during the subacute phase to assess HTs. The relationship between HLs and BBB disruption and HT was examined using the Alberta Stroke Program Early Computed Tomography Score locations in the symptomatic hemispheres. A HL was defined as a region where CBF relative ≥1.4 (CBF relative =CBF HL /CBF contralateral ). HLs, BBB disruption, and HT were found in 9, 15, and 15 patients, respectively. Compared with the patients without HLs, the patients with HLs had a higher incidence of both BBB disruption (100% versus 37.5%; P=0.003) and HT (100% versus 37.5%; P=0.003). Based on the Alberta Stroke Program Early Computed Tomography Score locations, 21 regions of interests displayed HLs. Compared with the regions of interests without HLs, the regions of interests with HLs had a higher incidence of both BBB disruption (42.8% versus 3.9%; P<0.001) and HT (85.7% versus 7.8%; P<0.001). HLs detected on pretreatment arterial spin-labeling maps may enable the prediction and localization of subsequent BBB disruption and HT. © 2016 American Heart Association, Inc.

Quantification of transient increase of the blood–brain barrier permeability to macromolecules by optimized focused ultrasound combined with microbubbles

PubMed Central

Shi, Lingyan; Palacio-Mancheno, Paolo; Badami, Joseph; Shin, Da Wi; Zeng, Min; Cardoso, Luis; Tu, Raymond; Fu, Bingmei M

2014-01-01

Radioimmunotherapy using a radiolabeled monoclonal antibody that targets tumor cells has been shown to be efficient for the treatment of many malignant cancers, with reduced side effects. However, the blood–brain barrier (BBB) inhibits the transport of intravenous antibodies to tumors in the brain. Recent studies have demonstrated that focused ultrasound (FUS) combined with microbubbles (MBs) is a promising method to transiently disrupt the BBB for the drug delivery to the central nervous system. To find the optimal FUS and MBs that can induce reversible increase in the BBB permeability, we employed minimally invasive multiphoton microscopy to quantify the BBB permeability to dextran-155 kDa with similar molecular weight to an antibody by applying different doses of FUS in the presence of MBs with an optimal size and concentration. The cerebral microcirculation was observed through a section of frontoparietal bone thinned with a micro-grinder. About 5 minutes after applying the FUS on the thinned skull in the presence of MBs for 1 minute, TRITC (tetramethylrhodamine isothiocyanate)-dextran-155 kDa in 1% bovine serum albumin in mammalian Ringer’s solution was injected into the cerebral circulation via the ipsilateral carotid artery by a syringe pump. Simultaneously, the temporal images were collected from the brain parenchyma ~100–200 μm below the pia mater. Permeability was determined from the rate of tissue solute accumulation around individual microvessels. After several trials, we found the optimal dose of FUS. At the optimal dose, permeability increased by ~14-fold after 5 minutes post-FUS, and permeability returned to the control level after 25 minutes. FUS without MBs or MBs injected without FUS did not change the permeability. Our method provides an accurate in vivo assessment for the transient BBB permeability change under the treatment of FUS. The optimal FUS dose found for the reversible BBB permeability increase without BBB disruption is reliable and can be applied to future clinical trials. PMID:25258533

BBB-Permeable, Neuroprotective, and Neurotrophic Polysaccharide, Midi-GAGR.

PubMed

Makani, Vishruti; Jang, Yong-Gil; Christopher, Kevin; Judy, Wesley; Eckstein, Jacob; Hensley, Kenneth; Chiaia, Nicolas; Kim, Dong-Shik; Park, Joshua

2016-01-01

An enormous amount of efforts have been poured to find an effective therapeutic agent for the treatment of neurodegenerative diseases including Alzheimer's disease (AD). Among those, neurotrophic peptides that regenerate neuronal structures and increase neuron survival show a promise in slowing neurodegeneration. However, the short plasma half-life and poor blood-brain-barrier (BBB)-permeability of neurotrophic peptides limit their in vivo efficacy. Thus, an alternative neurotrophic agent that has longer plasma half-life and better BBB-permeability has been sought for. Based on the recent findings of neuroprotective polysaccharides, we searched for a BBB-permeable neuroprotective polysaccharide among natural polysaccharides that are approved for human use. Then, we discovered midi-GAGR, a BBB-permeable, long plasma half-life, strong neuroprotective and neurotrophic polysaccharide. Midi-GAGR is a 4.7kD cleavage product of low acyl gellan gum that is approved by FDA for human use. Midi-GAGR protected rodent cortical neurons not only from the pathological concentrations of co-/post-treated free reactive radicals and Aβ42 peptide but also from activated microglial cells. Moreover, midi-GAGR showed a good neurotrophic effect; it enhanced neurite outgrowth and increased phosphorylated cAMP-responsive element binding protein (pCREB) in the nuclei of primary cortical neurons. Furthermore, intra-nasally administered midi-GAGR penetrated the BBB and exerted its neurotrophic effect inside the brain for 24 h after one-time administration. Midi-GAGR appears to activate fibroblast growth factor receptor 1 (FGFR1) and its downstream neurotrophic signaling pathway for neuroprotection and CREB activation. Additionally, 14-day intranasal administration of midi-GAGR not only increased neuronal activity markers but also decreased hyperphosphorylated tau, a precursor of neurofibrillary tangle, in the brains of the AD mouse model, 3xTg-AD. Taken together, midi-GAGR with good BBB-permeability, long plasma half-life, and strong neuroprotective and neurotrophic effects has a great therapeutic potential for the treatment of neurodegenerative diseases, especially AD.

BBB-Permeable, Neuroprotective, and Neurotrophic Polysaccharide, Midi-GAGR

PubMed Central

Makani, Vishruti; Jang, Yong-gil; Christopher, Kevin; Judy, Wesley; Eckstein, Jacob; Hensley, Kenneth; Chiaia, Nicolas; Kim, Dong-Shik; Park, Joshua

2016-01-01

An enormous amount of efforts have been poured to find an effective therapeutic agent for the treatment of neurodegenerative diseases including Alzheimer’s disease (AD). Among those, neurotrophic peptides that regenerate neuronal structures and increase neuron survival show a promise in slowing neurodegeneration. However, the short plasma half-life and poor blood-brain-barrier (BBB)-permeability of neurotrophic peptides limit their in vivo efficacy. Thus, an alternative neurotrophic agent that has longer plasma half-life and better BBB-permeability has been sought for. Based on the recent findings of neuroprotective polysaccharides, we searched for a BBB-permeable neuroprotective polysaccharide among natural polysaccharides that are approved for human use. Then, we discovered midi-GAGR, a BBB-permeable, long plasma half-life, strong neuroprotective and neurotrophic polysaccharide. Midi-GAGR is a 4.7kD cleavage product of low acyl gellan gum that is approved by FDA for human use. Midi-GAGR protected rodent cortical neurons not only from the pathological concentrations of co-/post-treated free reactive radicals and Aβ42 peptide but also from activated microglial cells. Moreover, midi-GAGR showed a good neurotrophic effect; it enhanced neurite outgrowth and increased phosphorylated cAMP-responsive element binding protein (pCREB) in the nuclei of primary cortical neurons. Furthermore, intra-nasally administered midi-GAGR penetrated the BBB and exerted its neurotrophic effect inside the brain for 24 h after one-time administration. Midi-GAGR appears to activate fibroblast growth factor receptor 1 (FGFR1) and its downstream neurotrophic signaling pathway for neuroprotection and CREB activation. Additionally, 14-day intranasal administration of midi-GAGR not only increased neuronal activity markers but also decreased hyperphosphorylated tau, a precursor of neurofibrillary tangle, in the brains of the AD mouse model, 3xTg-AD. Taken together, midi-GAGR with good BBB-permeability, long plasma half-life, and strong neuroprotective and neurotrophic effects has a great therapeutic potential for the treatment of neurodegenerative diseases, especially AD. PMID:26939023

Trojan Horse Transit Contributes to Blood-Brain Barrier Crossing of a Eukaryotic Pathogen.

PubMed

Santiago-Tirado, Felipe H; Onken, Michael D; Cooper, John A; Klein, Robyn S; Doering, Tamara L

2017-01-31

The blood-brain barrier (BBB) protects the central nervous system (CNS) by restricting the passage of molecules and microorganisms. Despite this barrier, however, the fungal pathogen Cryptococcus neoformans invades the brain, causing a meningoencephalitis that is estimated to kill over 600,000 people annually. Cryptococcal infection begins in the lung, and experimental evidence suggests that host phagocytes play a role in subsequent dissemination, although this role remains ill defined. Additionally, the disparate experimental approaches that have been used to probe various potential routes of BBB transit make it impossible to assess their relative contributions, confounding any integrated understanding of cryptococcal brain entry. Here we used an in vitro model BBB to show that a "Trojan horse" mechanism contributes significantly to fungal barrier crossing and that host factors regulate this process independently of free fungal transit. We also, for the first time, directly imaged C. neoformans-containing phagocytes crossing the BBB, showing that they do so via transendothelial pores. Finally, we found that Trojan horse crossing enables CNS entry of fungal mutants that cannot otherwise traverse the BBB, and we demonstrate additional intercellular interactions that may contribute to brain entry. Our work elucidates the mechanism of cryptococcal brain invasion and offers approaches to study other neuropathogens. The fungal pathogen Cryptococcus neoformans invades the brain, causing a meningoencephalitis that kills hundreds of thousands of people each year. One route that has been proposed for this brain entry is a Trojan horse mechanism, whereby the fungus crosses the blood-brain barrier (BBB) as a passenger inside host phagocytes. Although indirect experimental evidence supports this intriguing mechanism, it has never been directly visualized. Here we directly image Trojan horse transit and show that it is regulated independently of free fungal entry, contributes to cryptococcal BBB crossing, and allows mutant fungi that cannot enter alone to invade the brain. Copyright © 2017 Santiago-Tirado et al.

Very Mild Hypothermia (35°C) Postischemia Reduces Infarct Volume and Blood/Brain Barrier Breakdown Following tPA Treatment in the Mouse.

PubMed

Cechmanek, Brian K; Tuor, Ursula I; Rushforth, David; Barber, Philip A

2015-12-01

Reperfusion therapies for stroke diminish in effectiveness and safety as time to treatment increases. Hypothermia neuroprotection for stroke is established, but its clinical translation has been hampered by uncertainties regarding optimal temperature and complications associated with moderate hypothermia. Also, hypothermia targeting temperatures of 32-33°C is associated with clinical and logistical problems related to induction and adverse side effects. We hypothesized that ischemic damage and tPA-exacerbated blood/brain barrier (BBB) breakdown produced following 30 minutes of middle cerebral artery occlusion and either 1 hour of saline or tPA infusion would be reduced by treatment with very mild cooling of 1.5°C for 48 hours followed by 24 hours of gradual rewarming. Infarct volume was reduced by 29.6% (p<0.001) and 41.9% (p<0.001) in hypothermic-tPA (Hypo_tPA)-treated and hypothermic-saline (Hypo_Sal)-treated animals compared to normothermic-tPA (Norm_tPA) and saline (Norm_Sal)-treated animals, respectively. Hypothermia also reduced IgG extravasation in tPA-treated, but not saline-treated groups compared to their normothermic controls (p<0.001). The ipsilateral-contralateral changes in optical density for IgG extravasation were 18.4% greater in the Norm_tPA than Norm_Sal (p<0.001) group. The ipsilateral-contralateral changes in optical density for IgG extravasation were reduced by 17.8% (p<0.001) in the Hypo_tPA compared to Norm_tPA group. No significant mean difference in IgG extravasation was seen between Hypo_tPA and Hypo_Sal groups (p>0.05). Very modest hypothermia to reduce the BBB breakdown could improve the availability and safety of reperfusion treatments for stroke.

MANF prevents traumatic brain injury in rats by inhibiting inflammatory activation and protecting Blood Brain Barrier.

PubMed

Li, Qing-Xin; Shen, Yu-Xian; Ahmad, Akhlaq; Shen, Yu-Jun; Zhang, Yi-Quan; Xu, Pei-Kun; Chen, Wei-Wei; Yu, Yong-Qiang

2018-06-05

Our previous studies have shown that MANF provides neuroprotective effect against ischemia/reperfusion injury and is also involved in inflammatory disease models. This work investigates the potential role and mechanism of MANF in acute brain damage after traumatic brain injury (TBI). The model of TBI was induced by Feeney free falling methods with male Sprauge-Dawley rats. The expression of MANF, 24 hrs after TBI, was detected by the immunohistochemistry, immunofluorescence, Western blot and Reverse transcription PCR(RT-PCR) techniques. After treatment with recombinant human MANF following TBI, assessment was conducted - 24 hrs later for brain water content(BWC), cerebral edema volume in MRI, neurobehavioral testing and Evans blue extravasation. Moreover, by the techniques of Western blot and RT-PCR, the expression of inflammatory cytokines(IL-1β, TNF-α) and P65 was also analyzed to explore the underlying protective mechanism of MANF. At 24 hrs after TBI, we found that endogenous MANF was widely expressed in the rat's brain tissues and different types of cells. Treatment with high dose of recombinant human MANF(20 μg/20 μL) - significantly increased the modified Garcia score, and reduced BWC as well as cerebral edema volume in MRI. Furthermore, MANF alleviated not only the blood-brain barrier(BBB) permeability, but also the expressions of IL-1β and TNF-α mRNA and protein. Besides, the activation of P65 was also inhibited. These results suggest that MANF provides neuroprotective effect against acute brain injury after TBI, via attenuating BBB disruption and intracranial neuroinflammation, while the inhibition of NF-κB signaling pathway might be a potential mechanism. Copyright © 2018 Elsevier Inc. All rights reserved.

Targeted drug delivery across the blood brain barrier in Alzheimer's disease.

PubMed

Rocha, Sandra

2013-01-01

The discovery of drugs for Alzheimer's disease (AD) therapy that can also permeate the blood brain barrier (BBB) is very difficult owing to its specificity and restrictive nature. The BBB disruption or the administration of the drug directly into the brain is not an option due to toxic effects and low diffusion of the therapeutic molecule in the brain parenchyma. A promising approach for drug systemic delivery to the central nervous system is the use of nanosized carriers. The therapeutic potential of certain nanopharmaceuticals for AD has already been demonstrated in vivo after systemic delivery. They are based on i) conjugates of drug and monoclonal antibodies against BBB endogenous receptors; ii) cationized or end terminal protected proteins/peptides; iii) liposomes and polymeric nanoparticles coated with polysorbate 80, cationic macromolecules or antibodies against BBB receptors/amyloid beta-peptides. Optimization and further validation of these systems are needed.

Build back better: implementation in Victorian bushfire reconstruction.

PubMed

Mannakkara, Sandeeka; Wilkinson, Suzanne; Potangaroa, Regan

2014-04-01

The 'build back better' (BBB) concept signals an opportunity to decrease the vulnerability of communities to future disasters during post-disaster reconstruction and recovery. The 2009 Victorian bushfires in Australia serve as a case study for this assessment of the application of core BBB principles and their outcomes. The results show that several BBB measures were successfully implemented in Victoria and are relevant for any post-disaster reconstruction effort. The BBB initiatives taken in Victoria include: land-use planning determined by hazard risk-based zoning; enforcement of structural design improvements; facilitated permit procedures; regular consultations with stakeholders; and programmes conducted for social and economic recovery. Lessons from the Victorian recovery urge the avoidance of construction in high-risk zones; fairness and representativeness in community consultations; adequate support for economic recovery; the advance establishment of recovery frameworks; and empowerment of local councils. © 2014 The Author(s). Disasters © Overseas Development Institute, 2014.

In vitro and in vivo studies on the transport of PEGylated silica nanoparticles across the blood-brain barrier.

PubMed

Liu, Dan; Lin, Bingqian; Shao, Wei; Zhu, Zhi; Ji, Tianhai; Yang, Chaoyong

2014-02-12

Transport of PEGylated silica nanoparticles (PSiNPs) with diameters of 100, 50, and 25 nm across the blood-brain barrier (BBB) was evaluated using an in vitro BBB model based on mouse cerebral endothelial cells (bEnd.3) cultured on transwell inserts within a chamber. In vivo animal experiments were further performed by noninvasive in vivo imaging and ex vivo optical imaging after injection via carotid artery. Confocal fluorescence studies were carried out to evaluate the uptake of PSiNPs by brain endothelial cells. The results showed that PSiNPs can traverse the BBB in vitro and in vivo. The transport efficiency of PSiNPs across BBB was found to be size-dependent, with increased particle size resulting in decreased efficiency. This work points to the potential application of small sized silica nanoparticles in brain imaging or drug delivery.

Planar harmonic polynomials of type B

NASA Astrophysics Data System (ADS)

Dunkl, Charles F.

1999-11-01

The hyperoctahedral group acting on icons/Journals/Common/BbbR" ALT="BbbR" ALIGN="TOP"/>N is the Weyl group of type B and is associated with a two-parameter family of differential-difference operators {Ti:1icons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> iicons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> N}. These operators are analogous to partial derivative operators. This paper finds all the polynomials h on icons/Journals/Common/BbbR" ALT="BbbR" ALIGN="TOP"/>N which are harmonic, icons/Journals/Common/Delta" ALT="Delta" ALIGN="TOP"/>Bh = 0 and annihilated by Ti for i>2, where the Laplacian 0305-4470/32/46/308/img1" ALT="(sum). They are given explicitly in terms of a novel basis of polynomials, defined by generating functions. The harmonic polynomials can be used to find wavefunctions for the quantum many-body spin Calogero model.

Analytical and Biological Methods for Probing the Blood-Brain Barrier

PubMed Central

Sloan, Courtney D. Kuhnline; Nandi, Pradyot; Linz, Thomas H.; Aldrich, Jane V.; Audus, Kenneth L.; Lunte, Susan M.

2013-01-01

The blood-brain barrier (BBB) is an important interface between the peripheral and central nervous systems. It protects the brain against the infiltration of harmful substances and regulates the permeation of beneficial endogenous substances from the blood into the extracellular fluid of the brain. It can also present a major obstacle in the development of drugs that are targeted for the central nervous system. Several methods have been developed to investigate the transport and metabolism of drugs, peptides, and endogenous compounds at the BBB. In vivo methods include intravenous injection, brain perfusion, positron emission tomography, and microdialysis sampling. Researchers have also developed in vitro cell-culture models that can be employed to investigate transport and metabolism at the BBB without the complication of systemic involvement. All these methods require sensitive and selective analytical methods to monitor the transport and metabolism of the compounds of interest at the BBB. PMID:22708905

Permeability of the blood-brain barrier to the neurotensin8-13 analog NT1.

PubMed

Banks, W A; Wustrow, D J; Cody, W L; Davis, M D; Kastin, A J

1995-10-09

Neurotensin (NT) has been suggested to be a neuropeptide with therapeutic potential. We used multiple-time regression analysis to measure the unidirectional influx constant (Ki) of a tritiated analog of NT8-13, NT1, with improved metabolic stability. The Ki of [3H]NT1 across the blood-brain barrier (BBB) was 5.12(10(-4)) ml/g-min and was decreased 66% by unlabeled NT1 system. The amount of NT1 crossing the BBB, 0.087% of the injected dose per gram of brain, is consistent with its exerting central effects after peripheral administration. The stable [3H]NT1 crossed the BBB in intact form as assessed by HPLC and completely crossed the endothelial cells that comprise the BBB as assessed by the capillary depletion method. The presence of a transport system could be important for the development of NT analogs.

Pregnane X Receptor and P-glycoprotein: a connexion for Alzheimer's disease management.

PubMed

Jain, Sumit; Rathod, Vijay; Prajapati, Rameshwar; Nandekar, Prajwal P; Sangamwar, Abhay T

2014-11-01

The translational failure between preclinical animal models and clinical outcome has alarmed us to search for a new strategy in the treatment of Alzheimer's disease (AD). Interlink between Pregnane X Receptor (PXR) and P-glycoprotein (Pgp) at the blood brain barrier (BBB) has raised hope toward a new disease modifying therapy in AD. Pgp is a major efflux transporter for beta amyloid (Aβ) at human BBB. A literature survey reveals diminished expression of Pgp transporter at the BBB in AD patients. Pregnane X Receptor is a major transcriptional regulator of Pgp. Restoration of Pgp at the BBB enhances the elimination of the Aβ from brain alongside and inhibits the apical to basolateral movement of Aβ from the circulatory blood. This review concentrates on in vitro, in vivo, and in silico advancements on the study of the PXR in context to Pgp and discusses the substrate and inhibitor specificity between PXR and Pgp.

EMP-induced BBB-disruption enhances drug delivery to glioma and increases treatment efficacy in rats.

PubMed

Li, Kangchu; Zhang, Keying; Xu, Shenglong; Wang, Xiaowu; Zhou, Yongchun; Zhou, Yan; Gao, Peng; Lin, Jiajin; Ding, Guirong; Guo, Guozhen

2018-01-01

Chemotherapy on gliomas is not satisfactorily efficient because the presence of blood-brain barriers (BBB) leads to inadequate exposure of tumor cells to administered drugs. In order to facilitate chemotherapeutics to penetrate BBB and increase the treatment efficacy of gliomas, electromagnetic pulse (EMP) was applied and the 1-(2-Chlorethyl)-cyclohexyl-nitrosourea (CCNU) lomustine concentration in tumor tissue, tumor size, tumor apoptosis, and side effects were measured in glioma-bearing rat model. The results showed that EMP exposure could enhance the delivery of CCNU to tumor tissue, facilitate tumor apoptosis, and inhibit tumor growth without obvious side effects. The data indicated that EMP-induced BBB disruption could enhance delivery of CCNU to glioblastoma multiforme and increase treatment efficacy in glioma-bearing rats. Bioelectromagnetics. 39:60-67, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) produces edema due to BBB disruption induced by MMP-9 activation in rat hippocampus.

PubMed

Pérez-Hernández, Mercedes; Fernández-Valle, María Encarnación; Rubio-Araiz, Ana; Vidal, Rebeca; Gutiérrez-López, María Dolores; O'Shea, Esther; Colado, María Isabel

2017-05-15

The recreational drug of abuse, 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) disrupts blood-brain barrier (BBB) integrity in rats through an early P2X 7 receptor-mediated event which induces MMP-9 activity. Increased BBB permeability often causes plasma proteins and water to access cerebral tissue leading to vasogenic edema formation. The current study was performed to examine the effect of a single neurotoxic dose of MDMA (12.5 mg/kg, i.p.) on in vivo edema development associated with changes in the expression of the perivascular astrocytic water channel, AQP4, as well as in the expression of the tight-junction (TJ) protein, claudin-5 and Evans Blue dye extravasation in the hippocampus of adult male Dark Agouti rats. We also evaluated the ability of the MMP-9 inhibitor, SB-3CT (25 mg/kg, i.p.), to prevent these changes in order to validate the involvement of MMP-9 activation in MDMA-induced BBB disruption. The results show that MDMA produces edema of short duration temporally associated with changes in AQP4 expression and a reduction in claudin-5 expression, changes which are prevented by SB-3CT. In addition, MDMA induces a short-term increase in both tPA activity and expression, a serine-protease which is involved in BBB disruption and upregulation of MMP-9 expression. In conclusion, this study provides evidence enough to conclude that MDMA induces edema of short duration due to BBB disruption mediated by MMP-9 activation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effective Drug Delivery in Diffuse Intrinsic Pontine Glioma: A Theoretical Model to Identify Potential Candidates

PubMed Central

El-Khouly, Fatma E.; van Vuurden, Dannis G.; Stroink, Thom; Hulleman, Esther; Kaspers, Gertjan J. L.; Hendrikse, N. Harry; Veldhuijzen van Zanten, Sophie E. M.

2017-01-01

Despite decades of clinical trials for diffuse intrinsic pontine glioma (DIPG), patient survival does not exceed 10% at two years post-diagnosis. Lack of benefit from systemic chemotherapy may be attributed to an intact bloodbrain barrier (BBB). We aim to develop a theoretical model including relevant physicochemical properties in order to review whether applied chemotherapeutics are suitable for passive diffusion through an intact BBB or whether local administration via convection-enhanced delivery (CED) may increase their therapeutic potential. Physicochemical properties (lipophilicity, molecular weight, and charge in physiological environment) of anticancer drugs historically and currently administered to DIPG patients, that affect passive diffusion over the BBB, were included in the model. Subsequently, the likelihood of BBB passage of these drugs was ascertained, as well as their potential for intratumoral administration via CED. As only non-molecularly charged, lipophilic, and relatively small sized drugs are likely to passively diffuse through the BBB, out of 51 drugs modeled, only 8 (15%)—carmustine, lomustine, erlotinib, vismodegib, lenalomide, thalidomide, vorinostat, and mebendazole—are theoretically qualified for systemic administration in DIPG. Local administration via CED might create more therapeutic options, excluding only positively charged drugs and drugs that are either prodrugs and/or only available as oral formulation. A wide variety of drugs have been administered systemically to DIPG patients. Our model shows that only few are likely to penetrate the BBB via passive diffusion, which may partly explain the lack of efficacy. Drug distribution via CED is less dependent on physicochemical properties and may increase the therapeutic options for DIPG. PMID:29164054

Blood–Brain Barrier Leakage during Early Epileptogenesis Is Associated with Rapid Remodeling of the Neurovascular Unit

PubMed Central

Breuer, Heike; Leiter, Ina; Märkel, Martin; Bascuñana, Pablo; Michalski, Dominik; Bengel, Frank M.; Löscher, Wolfgang; Meier, Martin; Bankstahl, Jens P.; Härtig, Wolfgang

2018-01-01

Abstract Increased permeability of the blood–brain barrier (BBB) following cerebral injury results in regional extravasation of plasma proteins and can critically contribute to the pathogenesis of epilepsy. Here, we comprehensively explore the spatiotemporal evolution of a main extravasation component, albumin, and illuminate associated responses of the neurovascular unit (NVU) contributing to early epileptogenic neuropathology. We applied translational in vivo MR imaging and complementary immunohistochemical analyses in the widely used rat pilocarpine post–status epilepticus (SE) model. The observed rapid BBB leakage affected major epileptogenesis-associated brain regions, peaked between 1 and 2 d post-SE, and rapidly declined thereafter, accompanied by cerebral edema generally following the same time course. At peak of BBB leakage, serum albumin colocalized with NVU constituents, such as vascular components, neurons, and brain immune cells. Surprisingly, astroglial markers did not colocalize with albumin, and aquaporin-4 (AQP4) was clearly reduced in areas of leaky BBB, indicating a severe disturbance of astrocyte-mediated endothelial-neuronal coupling. In addition, a distinct adaptive reorganization process of the NVU vasculature apparently takes place at sites of albumin presence, substantiated by reduced immunoreactivity of endothelial and changes in vascular basement membrane markers. Taken together, degenerative events at the level of the NVU, affecting vessels, astrocytes, and neurons, seem to outweigh reconstructive processes. Considering the rapidly occurring BBB leakage and subsequent impairment of the NVU, our data support the necessity of a prompt BBB-restoring treatment as one component of rational therapeutic intervention to prevent epileptogenesis and the development of other detrimental sequelae of SE. PMID:29854942

Cancer-associated fibroblast promote transmigration through endothelial brain cells in three-dimensional in vitro models.

PubMed

Choi, Yoon Pyo; Lee, Joo Hyun; Gao, Ming-Qing; Kim, Baek Gil; Kang, Suki; Kim, Se Hoon; Cho, Nam Hoon

2014-11-01

Brain metastases are associated with high morbidity as well as with poor prognosis and survival in breast cancer patients. Despite its clinical importance, metastasis of breast cancer cells through the blood-brain barrier (BBB) is poorly understood. The objective of our study was to investigate whether cancer-associated fibroblasts (CAFs) play crucial roles in breast cancer brain metastasis. Using a cell adhesion assays, in vitro BBB permeability and transmigration assays and soft agar colony formation assays, we investigated the physical roles of CAFs in breast cancer brain metastasis. We also performed immunofluorescence, flow cytometric analysis, Droplet Digital PCR and Simon™ Simple Western System to confirm changes in expression levels. We established two novel three-dimensional (3D) culture systems using a perpendicular slide chamber and applying 3D embedded culture method to reflect brain metastasis conditions. With a newly developed device, CAFs was proven to promote cell adhesion to human brain microvascular endothelial cells, in vitro BBB permeability and transmigration and colony formation of breast cancer cells. Furthermore, CAFs enhanced the invasive migration of breast cancer cells in two kinds of 3D cultures. These 3D models also reliably recapitulate the initial steps of BBB transmigration, micro-metastasis and colonization. Expression of integrin α5β1 and αvβ3, c-MET and α2,6-siayltransferase was increased in breast cancer cells that migrated through the BBB. In conclusion, based on our in vitro BBB and co-culture models, our data suggest that CAFs may play a role in breast cancer brain metastasis. © 2014 UICC.

Western diets induce blood-brain barrier leakage and alter spatial strategies in rats.

PubMed

Hargrave, Sara L; Davidson, Terry L; Zheng, Wei; Kinzig, Kimberly P

2016-02-01

Western diet (WD) intake induces obesity and metabolic dysfunction. The present study examined the effects of WD on hippocampal-dependent cognitive functioning and blood-brain barrier (BBB) permeability as a function of exposure duration, obesity phenotype, and peripheral markers of energy regulation. The use of hippocampal-dependent "place" or hippocampal-independent "response" strategies in a Y maze was assessed in male rats following 10, 40, and 90 days of WD exposure in diet-induced obese (DIO) rats, in diet resistant (DR) rats that are relatively insensitive to the obesogenic properties of WD, and in chow-fed controls. Insulin, glucose, and BBB permeability throughout several loci in the hippocampus, striatum, and cerebellum were evaluated in relation to duration of WD exposure, obesity phenotype, and type of strategy used. DIO rats had increased body weight and adiposity throughout the study, and elevated 10-day glucose and 90-day insulin levels. Throughout the study, chow-fed and DR rats reliably relied on a place strategy. DIO rats, in contrast, favored a response strategy at the 10- and 90-day time points. BBB leakage was observed in the dorsal striatum and multiple subregions of the hippocampus of DIO, but not DR or chow-fed rats. Increased ventral hippocampal BBB permeability and blood glucose levels were associated with reduced place strategy use. These data indicate that WD-induced BBB leakage is dependent on duration of diet exposure as well as obesity phenotype, and implicates BBB leakage and impaired glucoregulation in behavioral strategy and cognitive performance. (c) 2016 APA, all rights reserved).

Overview and introduction: The blood–brain barrier in health and disease

PubMed Central

Abbott, N. Joan; Friedman, Alon

2013-01-01

Summary This article introduces the special issue on “Blood–Brain Barrier and Epilepsy.” We review briefly current understanding of the structure and function of the blood–brain barrier (BBB), including its development and normal physiology, and ways in which it can be affected in pathology. The BBB formed by the endothelium of cerebral blood vessels is one of three main barrier sites protecting the central nervous system (CNS). The barrier is not a rigid structure, but a dynamic interface with a range of interrelated functions, resulting from extremely effective tight junctions, transendothelial transport systems, enzymes, and regulation of leukocyte permeation, which thereby generates the physical, transport, enzymatic, and immune regulatory functions of the BBB. The brain endothelial cells are important components of a “modular” structure, the neurovascular unit (NVU), with several associated cell types and extracellular matrix components. Modern methods have helped in identifying a range of proteins involved in barrier structure and function, and recent studies have revealed important stages, cell types, and signaling pathways important in BBB development. There is a growing list of CNS pathologies showing BBB dysfunction, with strong evidence that this can play a major role in certain disease etiologies. The articles that follow in this issue summarize in more detail reports and discussions of the recent international meeting on “BBB in Neurological Dysfunctions,” which took place recently at Ben-Gurion University of the Negev Desert Campus (Beer-Sheva, Israel), focusing on the link between experimental and clinical studies, and the ways in which these lead to improved drug treatments. PMID:23134489

Protein kinase Cβ as a therapeutic target stabilizing blood–brain barrier disruption in experimental autoimmune encephalomyelitis

PubMed Central

Lanz, Tobias V.; Becker, Simon; Osswald, Matthias; Bittner, Stefan; Schuhmann, Michael K.; Opitz, Christiane A.; Gaikwad, Sadanand; Wiestler, Benedikt; Litzenburger, Ulrike M.; Sahm, Felix; Ott, Martina; Iwantscheff, Simeon; Grabitz, Carl; Mittelbronn, Michel; von Deimling, Andreas; Winkler, Frank; Meuth, Sven G.; Wick, Wolfgang; Platten, Michael

2013-01-01

Disruption of the blood–brain barrier (BBB) is a hallmark of acute inflammatory lesions in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis. This disruption may precede and facilitate the infiltration of encephalitogenic T cells. The signaling events that lead to this BBB disruption are incompletely understood but appear to involve dysregulation of tight-junction proteins such as claudins. Pharmacological interventions aiming at stabilizing the BBB in MS might have therapeutic potential. Here, we show that the orally available small molecule LY-317615, a synthetic bisindolylmaleimide and inhibitor of protein kinase Cβ, which is clinically under investigation for the treatment of cancer, suppresses the transmigration of activated T cells through an inflamed endothelial cell barrier, where it leads to the induction of the tight-junction molecules zona occludens-1, claudin 3, and claudin 5 and other pathways critically involved in transendothelial leukocyte migration. Treatment of mice with ongoing experimental autoimmune encephalomyelitis with LY-317615 ameliorates inflammation, demyelination, axonal damage, and clinical symptoms. Although LY-317615 dose-dependently suppresses T-cell proliferation and cytokine production independent of antigen specificity, its therapeutic effect is abrogated in a mouse model requiring pertussis toxin. This abrogation indicates that the anti-inflammatory and clinical efficacy is mainly mediated by stabilization of the BBB, thus suppressing the transmigration of encephalitogenic T cells. Collectively, our data suggest the involvement of endothelial protein kinase Cβ in stabilizing the BBB in autoimmune neuroinflammation and imply a therapeutic potential of BBB-targeting agents such as LY-317615 as therapeutic approaches for MS. PMID:23959874

Increased brain uptake of targeted nanoparticles by adding an acid-cleavable linkage between transferrin and the nanoparticle core.

PubMed

Clark, Andrew J; Davis, Mark E

2015-10-06

Most therapeutic agents are excluded from entering the central nervous system by the blood-brain barrier (BBB). Receptor mediated transcytosis (RMT) is a common mechanism used by proteins, including transferrin (Tf), to traverse the BBB. Here, we prepared Tf-containing, 80-nm gold nanoparticles with an acid-cleavable linkage between the Tf and the nanoparticle core to facilitate nanoparticle RMT across the BBB. These nanoparticles are designed to bind to Tf receptors (TfRs) with high avidity on the blood side of the BBB, but separate from their multidentate Tf-TfR interactions upon acidification during the transcytosis process to allow release of the nanoparticle into the brain. These targeted nanoparticles show increased ability to cross an in vitro model of the BBB and, most important, enter the brain parenchyma of mice in greater amounts in vivo after systemic administration compared with similar high-avidity nanoparticles containing noncleavable Tf. In addition, we investigated this design with nanoparticles containing high-affinity antibodies (Abs) to TfR. With the Abs, the addition of the acid-cleavable linkage provided no improvement to in vivo brain uptake for Ab-containing nanoparticles, and overall brain uptake was decreased for all Ab-containing nanoparticles compared with Tf-containing ones. These results are consistent with recent reports of high-affinity anti-TfR Abs trafficking to the lysosome within BBB endothelium. In contrast, high-avidity, Tf-containing nanoparticles with the acid-cleavable linkage avoid major endothelium retention by shedding surface Tf during their transcytosis.

Blood–brain barrier integrity, intrathecal immunoactivation, and neuronal injury in HIV

PubMed Central

Yilmaz, Aylin; Hagberg, Lars; Zetterberg, Henrik; Nilsson, Staffan; Brew, Bruce J.; Fuchs, Dietmar; Price, Richard W.; Gisslén, Magnus

2016-01-01

Objective: Although blood–brain barrier (BBB) impairment has been reported in HIV-infected individuals, characterization of this impairment has not been clearly defined. Methods: BBB integrity was measured by CSF/plasma albumin ratio in this cross-sectional study of 631 HIV-infected individuals and 71 controls. We also analyzed CSF and blood HIV RNA and neopterin, CSF leukocyte count, and neurofilament light chain protein (NFL) concentrations. The HIV-infected participants included untreated neuroasymptomatic patients, patients with untreated HIV-associated dementia (HAD), and participants on suppressive antiretroviral treatment (ART). Results: The albumin ratio was significantly increased in patients with HAD compared to all other groups. There were no significant differences between untreated neuroasymptomatic participants, treated participants, and controls. BBB integrity, however, correlated significantly with CSF leukocyte count, CSF HIV RNA, serum and CSF neopterin, and age in untreated neuroasymptomatic participants. In a multiple linear regression analysis, age, CSF neopterin, and CSF leukocyte count stood out as independent predictors of albumin ratio. A significant correlation was found between albumin ratio and CSF NFL in untreated neuroasymptomatic patients and in participants on ART. Albumin ratio, age, and CD4 cell count were confirmed as independent predictors of CSF NFL in multivariable analysis. Conclusions: BBB disruption was mainly found in patients with HAD, where BBB damage correlated with CNS immunoactivation. Albumin ratios also correlated with CSF inflammatory markers and NFL in untreated neuroasymptomatic participants. These findings give support to the association among BBB deterioration, intrathecal immunoactivation, and neuronal injury in untreated neuroasymptomatic HIV-infected individuals. PMID:27868081

Nanoscale drug delivery systems and the blood-brain barrier.

PubMed

Alyautdin, Renad; Khalin, Igor; Nafeeza, Mohd Ismail; Haron, Muhammad Huzaimi; Kuznetsov, Dmitry

2014-01-01

The protective properties of the blood-brain barrier (BBB) are conferred by the intricate architecture of its endothelium coupled with multiple specific transport systems expressed on the surface of endothelial cells (ECs) in the brain's vasculature. When the stringent control of the BBB is disrupted, such as following EC damage, substances that are safe for peripheral tissues but toxic to neurons have easier access to the central nervous system (CNS). As a consequence, CNS disorders, including degenerative diseases, can occur independently of an individual's age. Although the BBB is crucial in regulating the biochemical environment that is essential for maintaining neuronal integrity, it limits drug delivery to the CNS. This makes it difficult to deliver beneficial drugs across the BBB while preventing the passage of potential neurotoxins. Available options include transport of drugs across the ECs through traversing occludins and claudins in the tight junctions or by attaching drugs to one of the existing transport systems. Either way, access must specifically allow only the passage of a particular drug. In general, the BBB allows small molecules to enter the CNS; however, most drugs with the potential to treat neurological disorders other than infections have large structures. Several mechanisms, such as modifications of the built-in pumping-out system of drugs and utilization of nanocarriers and liposomes, are among the drug-delivery systems that have been tested; however, each has its limitations and constraints. This review comprehensively discusses the functional morphology of the BBB and the challenges that must be overcome by drug-delivery systems and elaborates on the potential targets, mechanisms, and formulations to improve drug delivery to the CNS.

Sphingosine 1-Phosphate Activation of EGFR As a Novel Target for Meningitic Escherichia coli Penetration of the Blood-Brain Barrier

PubMed Central

Wang, Xiangru; Maruvada, Ravi; Morris, Andrew J.; Liu, Jun O.; Baek, Dong Jae; Kim, Kwang Sik

2016-01-01

Central nervous system (CNS) infection continues to be an important cause of mortality and morbidity, necessitating new approaches for investigating its pathogenesis, prevention and therapy. Escherichia coli is the most common Gram-negative bacillary organism causing meningitis, which develops following penetration of the blood–brain barrier (BBB). By chemical library screening, we identified epidermal growth factor receptor (EGFR) as a contributor to E. coli invasion of the BBB in vitro. Here, we obtained the direct evidence that CNS-infecting E. coli exploited sphingosine 1-phosphate (S1P) for EGFR activation in penetration of the BBB in vitro and in vivo. We found that S1P was upstream of EGFR and participated in EGFR activation through S1P receptor as well as through S1P-mediated up-regulation of EGFR-related ligand HB-EGF, and blockade of S1P function through targeting sphingosine kinase and S1P receptor inhibited EGFR activation, and also E. coli invasion of the BBB. We further found that both S1P and EGFR activations occurred in response to the same E. coli proteins (OmpA, FimH, NlpI), and that S1P and EGFR promoted E. coli invasion of the BBB by activating the downstream c-Src. These findings indicate that S1P and EGFR represent the novel host targets for meningitic E. coli penetration of the BBB, and counteracting such targets provide a novel approach for controlling E. coli meningitis in the era of increasing resistance to conventional antibiotics. PMID:27711202

Selective targeting of a TNFR decoy receptor pharmaceutical to the primate brain as a receptor-specific IgG fusion protein.

PubMed

Boado, Ruben J; Hui, Eric Ka-Wai; Lu, Jeff Zhiqiang; Zhou, Qing-Hui; Pardridge, William M

2010-03-01

Decoy receptors, such as the human tumor necrosis factor receptor (TNFR), are potential new therapies for brain disorders. However, decoy receptors are large molecule drugs that are not transported across the blood-brain barrier (BBB). To enable BBB transport of a TNFR decoy receptor, the human TNFR-II extracellular domain was re-engineered as a fusion protein with a chimeric monoclonal antibody (MAb) against the human insulin receptor (HIR). The HIRMAb acts as a molecular Trojan horse to ferry the TNFR therapeutic decoy receptor across the BBB. The HIRMAb-TNFR fusion protein was expressed in stably transfected CHO cells, and was analyzed with electrophoresis, Western blotting, size exclusion chromatography, and binding assays for the HIR and TNFalpha. The HIRMAb-TNFR fusion protein was radio-labeled by trititation, in parallel with the radio-iodination of recombinant TNFR:Fc fusion protein, and the proteins were co-injected in the adult Rhesus monkey. The TNFR:Fc fusion protein did not cross the primate BBB in vivo, but the uptake of the HIRMAb-TNFR fusion protein was high and 3% of the injected dose was taken up by the primate brain. The TNFR was selectively targeted to brain, relative to peripheral organs, following fusion to the HIRMAb. This study demonstrates that decoy receptors may be re-engineered as IgG fusion proteins with a BBB molecular Trojan horse that selectively targets the brain, and enables penetration of the BBB in vivo. IgG-decoy receptor fusion proteins represent a new class of human neurotherapeutics. Copyright 2010 Elsevier B.V. All rights reserved.

Cellular mechanisms of IL-17-induced blood-brain barrier disruption.

PubMed

Huppert, Jula; Closhen, Dorothea; Croxford, Andrew; White, Robin; Kulig, Paulina; Pietrowski, Eweline; Bechmann, Ingo; Becher, Burkhard; Luhmann, Heiko J; Waisman, Ari; Kuhlmann, Christoph R W

2010-04-01

Recently T-helper 17 (Th17) cells were demonstrated to disrupt the blood-brain barrier (BBB) by the action of IL-17A. The aim of the present study was to examine the mechanisms that underlie IL-17A-induced BBB breakdown. Barrier integrity was analyzed in the murine brain endothelial cell line bEnd.3 by measuring the electrical resistance values using electrical call impedance sensing technology. Furthermore, in-cell Western blots, fluorescence imaging, and monocyte adhesion and transendothelial migration assays were performed. Experimental autoimmune encephalomyelitis (EAE) was induced in C57BL/6 mice. IL-17A induced NADPH oxidase- or xanthine oxidase-dependent reactive oxygen species (ROS) production. The resulting oxidative stress activated the endothelial contractile machinery, which was accompanied by a down-regulation of the tight junction molecule occludin. Blocking either ROS formation or myosin light chain phosphorylation or applying IL-17A-neutralizing antibodies prevented IL-17A-induced BBB disruption. Treatment of mice with EAE using ML-7, an inhibitor of the myosin light chain kinase, resulted in less BBB disruption at the spinal cord and less infiltration of lymphocytes via the BBB and subsequently reduced the clinical characteristics of EAE. These observations indicate that IL-17A accounts for a crucial step in the development of EAE by impairing the integrity of the BBB, involving augmented production of ROS.-Huppert, J., Closhen, D., Croxford, A., White, R., Kulig, P., Pietrowski, E., Bechmann, I., Becher, B., Luhmann, H. J., Waisman, A., Kuhlmann, C. R. W. Cellular mechanisms of IL-17-induced blood-brain barrier disruption.

Pharmacokinetics and safety in rhesus monkeys of a monoclonal antibody-GDNF fusion protein for targeted blood-brain barrier delivery.

PubMed

Pardridge, William M; Boado, Ruben J

2009-10-01

Glial-derived neurotrophic factor (GDNF) is a potential therapy for stroke, Parkinson's disease, or drug addiction. However, GDNF does not cross the blood-brain barrier (BBB). GDNF is re-engineered as a fusion protein with a chimeric monoclonal antibody (MAb) to the human insulin receptor (HIR), which acts as a molecular Trojan horse to deliver the GDNF across the BBB. The pharmacokinetics (PK), toxicology, and safety pharmacology of the HIRMAb-GDNF fusion protein were investigated in Rhesus monkeys. The fusion protein was administered as an intravenous injection at doses up to 50 mg/kg over a 60 h period to 56 Rhesus monkeys. The plasma concentration of the HIRMAb-GDNF fusion protein was measured with a 2-site sandwich ELISA. No adverse events were observed in a 2-week terminal toxicology study, and no neuropathologic changes were observed. The PK analysis showed a linear relationship between plasma AUC and dose, a large systemic volume of distribution, as well as high clearance rates of 8-10 mL/kg/min. A no-observable-adverse-effect level is established in the Rhesus monkey for the acute administration of the HIRMAb-GDNF fusion protein. The fusion protein targeting the insulin receptor has a PK profile similar to a classical small molecule.

Distribution of polymer nanoparticles by convection-enhanced delivery to brain tumors.

PubMed

Saucier-Sawyer, Jennifer K; Seo, Young-Eun; Gaudin, Alice; Quijano, Elias; Song, Eric; Sawyer, Andrew J; Deng, Yang; Huttner, Anita; Saltzman, W Mark

2016-06-28

Glioblastoma multiforme (GBM) is a fatal brain tumor characterized by infiltration beyond the margins of the main tumor mass and local recurrence after surgery. The blood-brain barrier (BBB) poses the most significant hurdle to brain tumor treatment. Convection-enhanced delivery (CED) allows for local administration of agents, overcoming the restrictions of the BBB. Recently, polymer nanoparticles have been demonstrated to penetrate readily through the healthy brain when delivered by CED, and size has been shown to be a critical factor for nanoparticle penetration. Because these brain-penetrating nanoparticles (BPNPs) have high potential for treatment of intracranial tumors since they offer the potential for cell targeting and controlled drug release after administration, here we investigated the intratumoral CED infusions of PLGA BPNPs in animals bearing either U87 or RG2 intracranial tumors. We demonstrate that the overall volume of distribution of these BPNPs was similar to that observed in healthy brains; however, the presence of tumors resulted in asymmetric and heterogeneous distribution patterns, with substantial leakage into the peritumoral tissue. Together, our results suggest that CED of BPNPs should be optimized by accounting for tumor geometry, in terms of location, size and presence of necrotic regions, to determine the ideal infusion site and parameters for individual tumors. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of a Rat Primary Cell-Based Blood-Brain Barrier Model With Epithelial and Brain Endothelial Cell Lines: Gene Expression and Drug Transport.

PubMed

Veszelka, Szilvia; Tóth, András; Walter, Fruzsina R; Tóth, Andrea E; Gróf, Ilona; Mészáros, Mária; Bocsik, Alexandra; Hellinger, Éva; Vastag, Monika; Rákhely, Gábor; Deli, Mária A

2018-01-01

Cell culture-based blood-brain barrier (BBB) models are useful tools for screening of CNS drug candidates. Cell sources for BBB models include primary brain endothelial cells or immortalized brain endothelial cell lines. Despite their well-known differences, epithelial cell lines are also used as surrogate models for testing neuropharmaceuticals. The aim of the present study was to compare the expression of selected BBB related genes including tight junction proteins, solute carriers (SLC), ABC transporters, metabolic enzymes and to describe the paracellular properties of nine different culture models. To establish a primary BBB model rat brain capillary endothelial cells were co-cultured with rat pericytes and astrocytes (EPA). As other BBB and surrogate models four brain endothelial cells lines, rat GP8 and RBE4 cells, and human hCMEC/D3 cells with or without lithium treatment (D3 and D3L), and four epithelial cell lines, native human intestinal Caco-2 and high P-glycoprotein expressing vinblastine-selected VB-Caco-2 cells, native MDCK and MDR1 transfected MDCK canine kidney cells were used. To test transporter functionality, the permeability of 12 molecules, glucopyranose, valproate, baclofen, gabapentin, probenecid, salicylate, rosuvastatin, pravastatin, atorvastatin, tacrine, donepezil, was also measured in the EPA and epithelial models. Among the junctional protein genes, the expression level of occludin was high in all models except the GP8 and RBE4 cells, and each model expressed a unique claudin pattern. Major BBB efflux (P-glycoprotein or ABCB1) and influx transporters (GLUT-1, LAT-1) were present in all models at mRNA levels. The transcript of BCRP (ABCG2) was not expressed in MDCK, GP8 and RBE4 cells. The absence of gene expression of important BBB efflux and influx transporters BCRP, MRP6, -9, MCT6, -8, PHT2, OATPs in one or both types of epithelial models suggests that Caco-2 or MDCK models are not suitable to test drug candidates which are substrates of these transporters. Brain endothelial cell lines GP8, RBE4, D3 and D3L did not form a restrictive paracellular barrier necessary for screening small molecular weight pharmacons. Therefore, among the tested culture models, the primary cell-based EPA model is suitable for the functional analysis of the BBB.

Drugs of abuse and blood-brain barrier endothelial dysfunction: A focus on the role of oxidative stress

PubMed Central

Sajja, Ravi K; Rahman, Shafiqur

2015-01-01

Psychostimulants and nicotine are the most widely abused drugs with a detrimental impact on public health globally. While the long-term neurobehavioral deficits and synaptic perturbations are well documented with chronic use of methamphetamine, cocaine, and nicotine, emerging human and experimental studies also suggest an increasing incidence of neurovascular complications associated with drug abuse. Short- or long-term administration of psychostimulants or nicotine is known to disrupt blood-brain barrier (BBB) integrity/function, thus leading to an increased risk of brain edema and neuroinflammation. Various pathophysiological mechanisms have been proposed to underlie drug abuse-induced BBB dysfunction suggesting a central and unifying role for oxidative stress in BBB endothelium and perivascular cells. This review discusses drug-specific effects of methamphetamine, cocaine, and tobacco smoking on brain microvascular crisis and provides critical assessment of oxidative stress-dependent molecular pathways focal to the global compromise of BBB. Additionally, given the increased risk of human immunodeficiency virus (HIV) encephalitis in drug abusers, we have summarized the synergistic pathological impact of psychostimulants and HIV infection on BBB integrity with an emphasis on unifying role of endothelial oxidative stress. This mechanistic framework would guide further investigations on specific molecular pathways to accelerate therapeutic approaches for the prevention of neurovascular deficits by drugs of abuse. PMID:26661236

Permeability of Endothelial and Astrocyte Cocultures: In Vitro Blood–Brain Barrier Models for Drug Delivery Studies

PubMed Central

Li, Guanglei; Simon, Melissa J.; Cancel, Limary M.; Shi, Zhong-Dong; Ji, Xinying; Tarbell, John M.; Morrison, Barclay; Fu, Bingmei M.

2014-01-01

The blood–brain barrier (BBB) is a major obstacle for drug delivery to the brain. To seek for in vitro BBB models that are more accessible than animals for investigating drug transport across the BBB, we compared four in vitro cultured cell models: endothelial monoculture (bEnd3 cell line), coculture of bEnd3 and primary rat astrocytes (coculture), coculture with collagen type I and IV mixture, and coculture with Matrigel. The expression of the BBB tight junction proteins in these in vitro models was assessed using RT-PCR and immunofluorescence. We also quantified the hydraulic conductivity (Lp), transendothelial electrical resistance (TER) and diffusive solute permeability (P) of these models to three solutes: TAMRA, Dextran 10K and Dextran 70K. Our results show that Lp and P of the endothelial monoculture and coculture models are not different from each other. Compared with in vivo permeability data from rat pial microvessels, P of the endothelial monoculture and coculture models are not significantly different from in vivo data for Dextran 70K, but they are 2–4 times higher for TAMRA and Dextran 10K. This suggests that the endothelial monoculture and all of the coculture models are fairly good models for studying the transport of relatively large solutes across the BBB. PMID:20361260

Permeability of endothelial and astrocyte cocultures: in vitro blood-brain barrier models for drug delivery studies.

PubMed

Li, Guanglei; Simon, Melissa J; Cancel, Limary M; Shi, Zhong-Dong; Ji, Xinying; Tarbell, John M; Morrison, Barclay; Fu, Bingmei M

2010-08-01

The blood-brain barrier (BBB) is a major obstacle for drug delivery to the brain. To seek for in vitro BBB models that are more accessible than animals for investigating drug transport across the BBB, we compared four in vitro cultured cell models: endothelial monoculture (bEnd3 cell line), coculture of bEnd3 and primary rat astrocytes (coculture), coculture with collagen type I and IV mixture, and coculture with Matrigel. The expression of the BBB tight junction proteins in these in vitro models was assessed using RT-PCR and immunofluorescence. We also quantified the hydraulic conductivity (L (p)), transendothelial electrical resistance (TER) and diffusive solute permeability (P) of these models to three solutes: TAMRA, Dextran 10K and Dextran 70K. Our results show that L (p) and P of the endothelial monoculture and coculture models are not different from each other. Compared with in vivo permeability data from rat pial microvessels, P of the endothelial monoculture and coculture models are not significantly different from in vivo data for Dextran 70K, but they are 2-4 times higher for TAMRA and Dextran 10K. This suggests that the endothelial monoculture and all of the coculture models are fairly good models for studying the transport of relatively large solutes across the BBB.

Adenosine receptor agonist NECA increases cerebral extravasation of fluorescein and low molecular weight dextran independent of blood-brain barrier modulation

PubMed Central

Cheng, Chih-Chung; Yang, Ya Lan; Liao, Kate Hsiurong; Lai, Ted Weita

2016-01-01

Conventional methods for therapeutic blood-brain barrier (BBB) disruption facilitate drug delivery but are cumbersome to perform. A previous study demonstrated that adenosine receptor (AR) stimulation by 5′-N-ethylcarboxamide adenosine (NECA) increased the extravasation of intravascular tracers into the brain and proposed that AR agonism may be an effective method for therapeutic BBB disruption. We attempted to confirm the extravasation of tracers into the brain and also investigated tracer extravasation into peripheral organs and tracer retention in the blood. We found that NECA not only increased the extravasation of intravascular fluorescein and low molecular weight dextran into the brain of mice but also increased the concentrations of these tracers in the blood. In fact, the brain:blood ratio-normalized BBB permeability for either tracer is actually decreased by NECA administration. Elevated blood urea nitrogen levels in mice following NECA treatment suggested that renal function impairment was a probable cause of tracer retention. Therefore, NECA has almost no effect on the extravasation of intravascular Evans blue dye (EBD), an albumin-binding tracer with little renal clearance. Rather than inducing BBB disruption, our study demonstrated that NECA increased tracer extravasation into the brain by increasing the concentration gradient of the tracer across the BBB. PMID:27025761

Early brain injury alters the blood-brain barrier phenotype in parallel with β-amyloid and cognitive changes in adulthood.

PubMed

Pop, Viorela; Sorensen, Dane W; Kamper, Joel E; Ajao, David O; Murphy, M Paul; Head, Elizabeth; Hartman, Richard E; Badaut, Jérôme

2013-02-01

Clinical studies suggest that traumatic brain injury (TBI) hastens cognitive decline and development of neuropathology resembling brain aging. Blood-brain barrier (BBB) disruption following TBI may contribute to the aging process by deregulating substance exchange between the brain and blood. We evaluated the effect of juvenile TBI (jTBI) on these processes by examining long-term alterations of BBB proteins, β-amyloid (Aβ) neuropathology, and cognitive changes. A controlled cortical impact was delivered to the parietal cortex of male rats at postnatal day 17, with behavioral studies and brain tissue evaluation at 60 days post-injury (dpi). Immunoglobulin G extravasation was unchanged, and jTBI animals had higher levels of tight-junction protein claudin 5 versus shams, suggesting the absence of BBB disruption. However, decreased P-glycoprotein (P-gp) on cortical blood vessels indicates modifications of BBB properties. In parallel, we observed higher levels of endogenous rodent Aβ in several brain regions of the jTBI group versus shams. In addition at 60 dpi, jTBI animals displayed systematic search strategies rather than relying on spatial memory during the water maze. Together, these alterations to the BBB phenotype after jTBI may contribute to the accumulation of toxic products, which in turn may induce cognitive differences and ultimately accelerate brain aging.

A novel synergetic targeting strategy for glioma therapy employing borneol combination with angiopep-2-modified, DOX-loaded PAMAM dendrimer.

PubMed

Han, Shunping; Zheng, Hongyue; Lu, Yanping; Sun, Yue; Huang, Anhao; Fei, Weidong; Shi, Xiaowei; Xu, Xiuling; Li, Jingjing; Li, Fanzhu

2018-01-01

Glioma is the most common primary malignant brain tumour and the effect of chemotherapy is hampered by low permeability across the blood-brain-barrier (BBB). Borneol is a time-honoured 'Guide' drug in traditional Chinese medicine and has been proved to be capable of promoting free drugs into the brain efficiently, but there are still risks that free drugs, especially anti-glioma drugs, may be disassembled and metabolised before penetrating the BBB and caused the whole brain distribution. The purpose of this paper was to investigate whether borneol intervention could facilitate the BBB penetration and assist glioma treatment by combining with doxorubicin (DOX) loaded PAMAM dendrimers drug delivery system modified with Angiopep-2 (a ligand of the low-density lipoprotein receptor-related protein, which overexpress both in the BBB and gliomas). The results demonstrated that Angiopep-2 modification could actually enhance the affinity between the dendrimers and the targeting cells and finally increase the cell uptake and boost the anti-tumour ability. Borneol physical combination could further enhance the anti-tumour efficiency of this targeting drug delivery system (TDDS) after penetrating BBB. Compared with free DOX solution, this TDDS illustrated obviously sustained and pH-dependent drug release. This suggested that this synergetic strategy provided a promising way for glioma therapy.

Adenosine receptor agonist NECA increases cerebral extravasation of fluorescein and low molecular weight dextran independent of blood-brain barrier modulation.

PubMed

Cheng, Chih-Chung; Yang, Ya Lan; Liao, Kate Hsiurong; Lai, Ted Weita

2016-03-30

Conventional methods for therapeutic blood-brain barrier (BBB) disruption facilitate drug delivery but are cumbersome to perform. A previous study demonstrated that adenosine receptor (AR) stimulation by 5'-N-ethylcarboxamide adenosine (NECA) increased the extravasation of intravascular tracers into the brain and proposed that AR agonism may be an effective method for therapeutic BBB disruption. We attempted to confirm the extravasation of tracers into the brain and also investigated tracer extravasation into peripheral organs and tracer retention in the blood. We found that NECA not only increased the extravasation of intravascular fluorescein and low molecular weight dextran into the brain of mice but also increased the concentrations of these tracers in the blood. In fact, the brain:blood ratio-normalized BBB permeability for either tracer is actually decreased by NECA administration. Elevated blood urea nitrogen levels in mice following NECA treatment suggested that renal function impairment was a probable cause of tracer retention. Therefore, NECA has almost no effect on the extravasation of intravascular Evans blue dye (EBD), an albumin-binding tracer with little renal clearance. Rather than inducing BBB disruption, our study demonstrated that NECA increased tracer extravasation into the brain by increasing the concentration gradient of the tracer across the BBB.

PPAR agonist-mediated protection against HIV Tat-induced cerebrovascular toxicity is enhanced in MMP-9-deficient mice

PubMed Central

Huang, Wen; Chen, Lei; Zhang, Bei; Park, Minseon; Toborek, Michal

2014-01-01

The strategies to protect against the disrupted blood–brain barrier (BBB) in HIV-1 infection are not well developed. Therefore, we investigated the potential of peroxisome proliferator-activated receptor (PPAR) agonists to prevent enhanced BBB permeability induced by HIV-1-specific protein Tat. Exposure to Tat via the internal carotid artery (ICA) disrupted permeability across the BBB; however, this effect was attenuated in mice treated with fenofibrate (PPARα agonist) or rosiglitazone (PPARγ agonist). In contrast, exposure to GW9662 (PPARγ antagonist) exacerbated Tat-induced disruption of the BBB integrity. Increased BBB permeability was associated with decreased tight junction (TJ) protein expression and activation of ERK1/2 and Akt in brain microvessels; these effects were attenuated by cotreatment with fenofibrate but not with rosiglitazone. Importantly, both PPAR agonists also protected against Tat-induced astrogliosis and neuronal loss. Because disruption of TJ integrity has been linked to matrix metalloproteinase (MMP) activity, we also evaluated Tat-induced effects in MMP-9-deficient mice. Tat-induced cerebrovascular toxicity, astrogliosis, and neuronal loss were less pronounced in MMP-9-deficient mice as compared with wild-type controls and were further attenuated by PPAR agonists. These results indicate that enhancing PPAR activity combined with targeting MMPs may provide effective therapeutic strategies in brain infection by HIV-1. PMID:24424383

Noninvasive delivery of stealth, brain-penetrating nanoparticles across the blood-brain barrier using MRI-guided focused ultrasound

PubMed Central

Miller, G. Wilson; Song, Ji; Louttit, Cameron; Klibanov, Alexander L; Shih, Ting-Yu; Swaminathan, Ganesh; Tamargo, Rafael J.; Woodworth, Graeme F.; Hanes, Justin; Price, Richard J.

2014-01-01

The blood-brain barrier (BBB) presents a significant obstacle for the treatment of many central nervous system (CNS) disorders, including invasive brain tumors, Alzheimer’s, Parkinson’s and stroke. Therapeutics must be capable of bypassing the BBB and also penetrate the brain parenchyma to achieve a desired effect within the brain. In this study, we test the unique combination of a noninvasive approach to BBB permeabilization with a therapeutically relevant polymeric nanoparticle platform capable of rapidly penetrating within the brain microenvironment. MR-guided focused ultrasound (FUS) with intravascular microbubbles (MBs) is able to locally and reversibly disrupt the BBB with submillimeter spatial accuracy. Densely poly(ethylene-co-glycol) (PEG) coated, brain-penetrating nanoparticles (BPNs) are long-circulating and diffuse 10-fold slower in normal rat brain tissue compared to diffusion in water. Following intravenous administration of model and biodegradable BPN in normal healthy rats, we demonstrate safe, pressure-dependent delivery of 60 nm BPNs to the brain parenchyma in regions where the BBB is disrupted by FUS and MBs. Delivery of BPNs with MR-guided FUS has the potential to improve efficacy of treatments for many CNS diseases, while reducing systemic side effects by providing sustained, well-dispersed drug delivery into select regions of the brain. PMID:24979210

Trojan Horse Transit Contributes to Blood-Brain Barrier Crossing of a Eukaryotic Pathogen

PubMed Central

Santiago-Tirado, Felipe H.; Onken, Michael D.; Cooper, John A.; Klein, Robyn S.

2017-01-01

ABSTRACT The blood-brain barrier (BBB) protects the central nervous system (CNS) by restricting the passage of molecules and microorganisms. Despite this barrier, however, the fungal pathogen Cryptococcus neoformans invades the brain, causing a meningoencephalitis that is estimated to kill over 600,000 people annually. Cryptococcal infection begins in the lung, and experimental evidence suggests that host phagocytes play a role in subsequent dissemination, although this role remains ill defined. Additionally, the disparate experimental approaches that have been used to probe various potential routes of BBB transit make it impossible to assess their relative contributions, confounding any integrated understanding of cryptococcal brain entry. Here we used an in vitro model BBB to show that a “Trojan horse” mechanism contributes significantly to fungal barrier crossing and that host factors regulate this process independently of free fungal transit. We also, for the first time, directly imaged C. neoformans-containing phagocytes crossing the BBB, showing that they do so via transendothelial pores. Finally, we found that Trojan horse crossing enables CNS entry of fungal mutants that cannot otherwise traverse the BBB, and we demonstrate additional intercellular interactions that may contribute to brain entry. Our work elucidates the mechanism of cryptococcal brain invasion and offers approaches to study other neuropathogens. PMID:28143979

Prediction of blood-brain partitioning: a model based on molecular electronegativity distance vector descriptors.

PubMed

Zhang, Yong-Hong; Xia, Zhi-Ning; Qin, Li-Tang; Liu, Shu-Shen

2010-09-01

The objective of this paper is to build a reliable model based on the molecular electronegativity distance vector (MEDV) descriptors for predicting the blood-brain barrier (BBB) permeability and to reveal the effects of the molecular structural segments on the BBB permeability. Using 70 structurally diverse compounds, the partial least squares regression (PLSR) models between the BBB permeability and the MEDV descriptors were developed and validated by the variable selection and modeling based on prediction (VSMP) technique. The estimation ability, stability, and predictive power of a model are evaluated by the estimated correlation coefficient (r), leave-one-out (LOO) cross-validation correlation coefficient (q), and predictive correlation coefficient (R(p)). It has been found that PLSR model has good quality, r=0.9202, q=0.7956, and R(p)=0.6649 for M1 model based on the training set of 57 samples. To search the most important structural factors affecting the BBB permeability of compounds, we performed the values of the variable importance in projection (VIP) analysis for MEDV descriptors. It was found that some structural fragments in compounds, such as -CH(3), -CH(2)-, =CH-, =C, triple bond C-, -CH<, =C<, =N-, -NH-, =O, and -OH, are the most important factors affecting the BBB permeability. (c) 2010. Published by Elsevier Inc.

Lysophosphatidic acid receptor, LPA6, regulates endothelial blood-brain barrier function: Implication for hepatic encephalopathy.

PubMed

Masago, Kayo; Kihara, Yasuyuki; Yanagida, Keisuke; Hamano, Fumie; Nakagawa, Shinsuke; Niwa, Masami; Shimizu, Takao

2018-07-02

Cerebral edema is a life-threatening neurological condition characterized by brain swelling due to the accumulation of excess fluid both intracellularly and extracellularly. Fulminant hepatic failure (FHF) develops cerebral edema by disrupting blood-brain barrier (BBB). However, the mechanisms by which mediator induces brain edema in FHF remain to be elucidated. Here, we assessed a linkage between brain edema and lysophosphatidic acid (LPA) signaling by utilizing an animal model of FHF and in vitro BBB model. Azoxymethane-treated mice developed FHF and hepatic encephalopathy, associated with higher autotaxin (ATX) activities in serum than controls. Using in vitro BBB model, LPA disrupted the structural integrity of tight junction proteins including claudin-5, occludin, and ZO-1. Furthermore, LPA decreased transendothelial electrical resistances in in vitro BBB model, and induced cell contraction in brain endothelial monolayer cultures, both being inhibited by a Rho-associated protein kinase inhibitor, Y-27632. The brain capillary endothelial cells predominantly expressed LPA 6 mRNA, whose knockdown blocked the LPA-induced endothelial cell contraction. Taken together, the up-regulation of serum ATX in hepatic encephalopathy may activate the LPA-LPA 6 -G 12/13 -Rho pathway in brain capillary endothelial cells, leading to enhancement of BBB permeability and brain edema. Copyright © 2018 Elsevier Inc. All rights reserved.

Essentials and Perspectives of Computational Modelling Assistance for CNS-oriented Nanoparticle-based Drug Delivery Systems.

PubMed

Kisała, Joanna; Heclik, Kinga I; Pogocki, Krzysztof; Pogocki, Dariusz

2018-05-16

The blood-brain barrier (BBB) is a complex system controlling two-way substances traffic between circulatory (cardiovascular) system and central nervous system (CNS). It is almost perfectly crafted to regulate brain homeostasis and to permit selective transport of molecules that are essential for brain function. For potential drug candidates, the CNS-oriented neuropharmaceuticals as well as for those of primary targets in the periphery, the extent to which a substance in the circulation gains access to the CNS seems crucial. With the advent of nanopharmacology the problem of the BBB permeability for drug nano-carriers gains new significance. Compare to some other fields of medicinal chemistry, the computational science of nanodelivery is still prematured to offer the black-box type solutions, especially for the BBB-case. However, even its enormous complexity can be spell out the physical principles, and as such subjected to computation. Basic understanding of various physico-chemical parameters describing the brain uptake is required to take advantage of their usage for the BBB-nanodelivery. This mini-review provides a sketchy introduction into essential concepts allowing application of computational simulation to the BBB-nanodelivery design. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Blood-brain barrier shuttle peptides enhance AAV transduction in the brain after systemic administration.

PubMed

Zhang, Xintao; He, Ting; Chai, Zheng; Samulski, R Jude; Li, Chengwen

2018-09-01

The adeno-associated virus (AAV) vector has been used in preclinical and clinical trials of gene therapy for central nervous system (CNS) diseases. One of the biggest challenges of effectively delivering AAV to the brain is to surmount the blood-brain barrier (BBB). Herein, we identified several potential BBB shuttle peptides that significantly enhanced AAV8 transduction in the brain after a systemic administration, the best of which was the THR peptide. The enhancement of AAV8 brain transduction by THR is dose-dependent, and neurons are the primary THR targets. Mechanism studies revealed that THR directly bound to the AAV8 virion, increasing its ability to cross the endothelial cell barrier. Further experiments showed that binding of THR to the AAV virion did not interfere with AAV8 infection biology, and that THR competitively blocked transferrin from binding to AAV8. Taken together, our results demonstrate, for the first time, that BBB shuttle peptides are able to directly interact with AAV and increase the ability of the AAV vectors to cross the BBB for transduction enhancement in the brain. These results will shed important light on the potential applications of BBB shuttle peptides for enhancing brain transduction with systemic administration of AAV vectors. Copyright © 2018 Elsevier Ltd. All rights reserved.

Blood-brain barrier leakage after status epilepticus in rapamycin-treated rats II: Potential mechanisms.

PubMed

van Vliet, Erwin A; Otte, Willem M; Wadman, Wytse J; Aronica, Eleonora; Kooij, Gijs; de Vries, Helga E; Dijkhuizen, Rick M; Gorter, Jan A

2016-01-01

Blood-brain barrier (BBB) leakage may play a pro-epileptogenic role after status epilepticus. In the accompanying contrast-enhanced magnetic resonance imaging (CE-MRI) study we showed that the mammalian target of rapamycin (mTOR) inhibitor rapamycin reduced BBB leakage and seizure activity during the chronic epileptic phase. Given rapamycin's role in growth and immune response, the potential therapeutic effects of rapamycin after status epilepticus with emphasis on brain inflammation and brain vasculature were investigated. Seven weeks after kainic acid-induced status epilepticus, rats were perfusion fixed and (immuno)histochemistry was performed using several glial and vascular markers. In addition, an in vitro model for the human BBB was used to determine the effects of rapamycin on transendothelial electrical resistance as a measure for BBB integrity. (Immuno)histochemistry showed that local blood vessel density, activated microglia, and astrogliosis were reduced in rapamycin-treated rats compared to vehicle-treated rats. In vitro studies showed that rapamycin could attenuate TNFα-induced endothelial barrier breakdown. These data suggest that rapamycin improves BBB function during the chronic epileptic phase by a reduction of local brain inflammation and blood vessel density that can contribute to a milder form of epilepsy. Wiley Periodicals, Inc. © 2015 International League Against Epilepsy.

Whole body vibration (WBV) following spinal cord injury (SCI) in rats: Timing of intervention.

PubMed

Manthou, Marilena; Abdulla, Diana Saad Yousif; Pavlov, Stoyan Pavlov; Jansen, Ramona; Bendella, Habib; Nohroudi, Klaus; Stein, Gregor; Meyer, Carolin; Ozsoy, Ozlem; Ozsoy, Umut; Behram Kandemir, Yasemin; Sarikcioglu, Levent; Semler, Oliver; Schoenau, Eckhard; Dunlop, Sarah; Angelov, Doychin Nikolov

2017-01-01

Following spinal cord injury (SCI), exercise training provides a wide range of benefits and promotes activity-dependent synaptic plasticity. Whole body vibration (WBV) in SCI patients improves walking and spasticity as well as bone and muscle mass. However, little is known about the effects of timing or frequency of intervention. To determine which WBV-onset improves locomotor and bladder functions and influences synaptic plasticity beneficially. SCI was followed by WBV starting 1, 7, 14, 28 days after injury (WBV1, WBV7, etc.) and continued for 12 weeks. Intact animals and those receiving SCI but no WBV (No WBV), SCI plus WBV twice daily (2×WBV) and SCI followed by passive hindlimb flexion-extension (PFE) served as controls. Locomotor [BBB rating, foot stepping angle (FSA) and rump-height index (RHI)] as well as bladder function were determined at 1, 3, 6, 9, and 12 weeks. Following perfusion fixation at 12 weeks, lesion volume and immunofluorescence for astrogliosis (GFAP), microglia (IBA1) and synaptic vesicles (synaptophysin, SYN) were determined. Compared to the No WBV group, the WB7 and WBV14 groups showed significantly faster speeds of BBB score recovery though this effect was temporary. Considering RHI we detected a sustained improvement in the WBV14 and PFE groups. Bladder function was better in the WBV14, WBV28, 2×WBV and PFE groups. Synaptophysin levels improved in response to WBV7 and WBV14, but worsened after WBV28 in parallel to an increased IBA1 expression. Correlation- and principal components analysis revealed complex relationships between behavioural (BBB, FSA, RHI) and morphological (GFAP, IBA1, SYN) measurements. WBV started 14 days after SCI provides the most benefit (RHI, bladder); starting at 1day after SCI provides no benefit and starting at 28 days may be detrimental. Increasing the intensity of WBV to twice daily did not provide additional benefit.

Neuroprotective effect of interleukin-6 in a rat model of cerebral ischemia

PubMed Central

FENG, QILIN; WANG, YI; YANG, YINGDA

2015-01-01

Interleukin (IL)-6 is known to be a key cytokine in immune regulation in addition to serving crucial functions in various autoimmune diseases; however, the neuroprotective potential of IL-6 has not been fully investigated. The aim of the present study was to investigate the neuroprotective effects of the inflammatory cytokine IL-6 in a rat model of cerebral ischemia. Rat cerebral ischemia was induced by intraluminal middle cerebral artery occlusion. Following treatment with 500 or 50 ng IL-6, the infarct volumes and symptoms of neurological deficit were ameliorated. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining suggested that the IL-6 treatment reduced neuronal apoptosis in vivo, which was consistent with a lower percentage of annexin V- and caspase-3-positive cortical neurons. In addition, IL-6 in vitro induced the phosphorylation of signal transducer and activator of transcription (STAT) 3 and the expression of induced myeloid leukemia cell differentiation protein Mcl-1, but not the expression of B-cell lymphoma 2, suggesting the activation of the Janus kinase/STAT pathway by IL-6. IL-6 also appeared to be involved in the regulation of cytokine secretion and blood-brain barrier (BBB) integrity in cerebral ischemia. IL-6 downregulated a number of inflammatory cytokines, including tumor necrosis factor-α and IL-1β, as well as myeloperoxidase activity, indicating the accumulation of granulocytes in the ischemic brain tissue. IL-6 was also observed to support the integrity of the BBB by reducing Evans blue leakage in vivo and suppressing the expression of matrix metalloproteinase-9 in ischemic brain tissue. In conclusion, the results of the present study indicate that the neuroprotective effects of IL-6 in cerebral ischemia are the result of a range of processes, including the modulation of cell apoptosis, cytokine secretion and the integrity of the BBB. IL-6 could therefore be used as a therapeutic agent in clinical practice. PMID:26136879

Protecting the BBB Endothelium against Cigarette Smoke-Induced Oxidative Stress Using Popular Antioxidants: Are they really beneficial?

PubMed Central

Kaisar, Mohammad Abul; Prasad, Shikha; Cucullo, Luca

2015-01-01

Blood Brain Barrier (BBB) exposed to realistic concentrations (comparable to a chronic heavy smoker) of Cigarette Smoke Extract (CSE) triggers a strong endothelial inflammatory which can lead to the onset of neurological disorders. The involvement of Reactive Oxygen Species (ROS) in this inflammatory cascade is evident from the up-regulation of nuclear factor erythroid 2 related factor 2 (Nrf-2), a transcription factor involved in anti-oxidant response signaling in CSE exposed endothelial cells. We have shown that pre-treatment with α-tocopherol and/or ascorbic acid is highly protective for the BBB, thus suggesting that, prophylactic administration of antioxidants can reduce CSE and/or inflammatory-dependent BBB damage. We have assessed and ranked the protective effects of 5 popular OTC antioxidants (Coenzyme Q10, Melatonin, Glutathione, Lipoic acid and Resveratrol) against CSE-induced BBB endothelial damage using hCMEC/D3 cells. The analysis of pro-inflammatory cytokines release by ELISA revealed that, resveratrol, lipoic acid melatonin and Co-Q10 inhibited the BBB endothelial release of pro-inflammatory cytokines IL-6 & IL-8, reduced (not Co-Q10) CSE-induced up-regulation of Platelet Endothelial Cell Adhesion Molecule -1 (PECAM-1), Vascular Endothelial Cell Adhesion Molecule-1 (VCAM-1) & E-selectin and inhibited monocytes-endothelial cell adhesion. The anti-inflammatory effects correlated with the anti-oxidative protection endowed by these compounds as evidenced by upregulation of NADPH: Quinone Oxidoreductase 1 (NQO1) and reduced cellular oxidative stress. CSE-induced release of Vascular Endothelial Growth Factor (VEGF) was inhibited by all tested compounds although the effect was not strictly dose-dependent. Further in vivo studies are required to validate our results and expand our current study to include combinatorial treatments. PMID:26410779

Nanoscale drug delivery systems and the blood–brain barrier

PubMed Central

Alyautdin, Renad; Khalin, Igor; Nafeeza, Mohd Ismail; Haron, Muhammad Huzaimi; Kuznetsov, Dmitry

2014-01-01

The protective properties of the blood–brain barrier (BBB) are conferred by the intricate architecture of its endothelium coupled with multiple specific transport systems expressed on the surface of endothelial cells (ECs) in the brain’s vasculature. When the stringent control of the BBB is disrupted, such as following EC damage, substances that are safe for peripheral tissues but toxic to neurons have easier access to the central nervous system (CNS). As a consequence, CNS disorders, including degenerative diseases, can occur independently of an individual’s age. Although the BBB is crucial in regulating the biochemical environment that is essential for maintaining neuronal integrity, it limits drug delivery to the CNS. This makes it difficult to deliver beneficial drugs across the BBB while preventing the passage of potential neurotoxins. Available options include transport of drugs across the ECs through traversing occludins and claudins in the tight junctions or by attaching drugs to one of the existing transport systems. Either way, access must specifically allow only the passage of a particular drug. In general, the BBB allows small molecules to enter the CNS; however, most drugs with the potential to treat neurological disorders other than infections have large structures. Several mechanisms, such as modifications of the built-in pumping-out system of drugs and utilization of nanocarriers and liposomes, are among the drug-delivery systems that have been tested; however, each has its limitations and constraints. This review comprehensively discusses the functional morphology of the BBB and the challenges that must be overcome by drug-delivery systems and elaborates on the potential targets, mechanisms, and formulations to improve drug delivery to the CNS. PMID:24550672

Nano carriers for drug transport across the blood-brain barrier.

PubMed

Li, Xinming; Tsibouklis, John; Weng, Tingting; Zhang, Buning; Yin, Guoqiang; Feng, Guangzhu; Cui, Yingde; Savina, Irina N; Mikhalovska, Lyuba I; Sandeman, Susan R; Howel, Carol A; Mikhalovsky, Sergey V

2017-01-01

Effective therapy lies in achieving a therapeutic amount of drug to the proper site in the body and then maintaining the desired drug concentration for a sufficient time interval to be clinically effective for treatment. The blood-brain barrier (BBB) hinders most drugs from entering the central nervous system (CNS) from the blood stream, leading to the difficulty of delivering drugs to the brain via the circulatory system for the treatment, diagnosis and prevention of brain diseases. Several brain drug delivery approaches have been developed, such as intracerebral and intracerebroventricular administration, intranasal delivery and blood-to-brain delivery, as a result of transient BBB disruption induced by biological, chemical or physical stimuli such as zonula occludens toxin, mannitol, magnetic heating and ultrasound, but these approaches showed disadvantages of being dangerous, high cost and unsuitability for most brain diseases and drugs. The strategy of vector-mediated blood-to-brain delivery, which involves improving BBB permeability of the drug-carrier conjugate, can minimize side effects, such as being submicrometre objects that behave as a whole unit in terms of their transport and properties, nanomaterials, are promising carrier vehicles for direct drug transport across the intact BBB as a result of their potential to enter the brain capillary endothelial cells by means of normal endocytosis and transcytosis due to their small size, as well as their possibility of being functionalized with multiple copies of the drug molecule of interest. This review provids a concise discussion of nano carriers for drug transport across the intact BBB, various forms of nanomaterials including inorganic/solid lipid/polymeric nanoparticles, nanoemulsions, quantum dots, nanogels, liposomes, micelles, dendrimers, polymersomes and exosomes are critically evaluated, their mechanisms for drug transport across the BBB are reviewed, and the future directions of this area are fully discussed.

Transport across the blood-brain barrier of pluronic leptin.

PubMed

Price, Tulin O; Farr, Susan A; Yi, Xiang; Vinogradov, Serguei; Batrakova, Elena; Banks, William A; Kabanov, Alexander V

2010-04-01

Leptin is a peptide hormone produced primarily by adipose tissue that acts as a major regulator of food intake and energy homeostasis. Impaired transport of leptin across the blood-brain barrier (BBB) contributes to leptin resistance, which is a cause of obesity. Leptin as a candidate for the treatment of this obesity is limited because of the short half-life in circulation and the decreased BBB transport that arises in obesity. Chemical modification of polypeptides with amphiphilic poly(ethylene oxide)-poly(propylene oxide) block copolymers (Pluronic) is a promising technology to improve efficiency of delivery of polypeptides to the brain. In the present study, we determined the effects of Pluronic P85 (P85) with intermediate hydrophilic-lipophilic balance conjugated with leptin via a degradable SS bond [leptin(ss)-P85] on food intake, clearance, stability, and BBB uptake. The leptin(ss)-P85 exhibited biological activity when injected intracerebroventricularly after overnight food deprivation and 125I-leptin(ss)-P85 was stable in blood, with a half-time clearance of 32.3 min (versus 5.46 min for leptin). 125I-Leptin(ss)-P85 crossed the BBB [blood-to-brain unidirectional influx rate (K(i)) = 0.272 +/- 0.037 microl/g x min] by a nonsaturable mechanism unrelated to the leptin transporter. Capillary depletion showed that most of the 125I-leptin(ss)-P85 taken up by the brain reached the brain parenchyma. Food intake was reduced when 3 mg of leptin(ss)-P85 was administered via tail vein in normal body weight mice [0-30 min, p < 0.0005; 0-2 h, p < 0.001]. These studies show that the structure based Pluronic modification of leptin increased metabolic stability, reduced food intake, and allowed BBB penetration by a mechanism-independent BBB leptin transporter.

Blood-brain barrier (BBB) toxicity and permeability assessment after L-(4-¹⁰Boronophenyl)alanine, a conventional B-containing drug for boron neutron capture therapy, using an in vitro BBB model.

PubMed

Roda, E; Nion, S; Bernocchi, G; Coccini, T

2014-10-02

Since brain tumours are the primary candidates for treatment by Boron Neutron Capture Therapy, one major challenge in the selective drug delivery to CNS is the crossing of the blood-brain barrier (BBB). The present pilot study investigated (i) the transport of a conventional B-containing product (i.e., L-(4-(10)Boronophenyl)alanine, L-(10)BPA), already used in medicine but still not fully characterized regarding its CNS interactions, as well as (ii) the effects of the L-(10)BPA on the BBB integrity using an in vitro model, consisting of brain capillary endothelial cells co-cultured with glial cells, closely mimicking the in vivo conditions. The multi-step experimental strategy (i.e. Integrity test, Filter study, Transport assay) checked L-(10)BPA toxicity at 80 µg Boron equivalent/ml, and its ability to cross the BBB, additionally by characterizing the cytoskeletal and TJ's proteins by immunocytochemistry and immunoblotting. In conclusion, a lack of toxic effects of L-(10)BPA was demonstrated, nevertheless accompanied by cellular stress phenomena (e.g. vimentin expression modification), paralleled by a low permeability coefficient (0.39 ± 0.01 × 10(-3)cm min(-1)), corroborating the scarce probability that L-(10)BPA would reach therapeutically effective cerebral concentration. These findings emphasized the need for novel strategies aimed at optimizing boron delivery to brain tumours, trying to ameliorate the compound uptake or developing new targeted products suitable to safely and effectively treat head cancer. Thus, the use of in vitro BBB model for screening studies may provide a useful early safety assessment for new effective compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

Blood-brain barrier permeability is increased after acute adult stroke but not neonatal stroke in the rat

PubMed Central

Lopez, David Fernandez; Faustino, Joel; Daneman, Richard; Zhou, Lu; Lee, Sarah; Derugin, Nikita; Wendland, Michael F.; Vexler, Zinaida S

2012-01-01

The immaturity of the CNS at birth greatly affects injury after stroke but the contribution of the blood-brain barrier (BBB) to the differential response to stroke in adults and neonates is poorly understood. We asked if the structure and function of the BBB is disrupted differently in neonatal and adult rats by transient middle cerebral artery occlusion. In adult rats, albumin leakage into injured regions was markedly increased during 2–24 h reperfusion but leakage remained low in the neonates. Functional assays employing intravascular tracers in the neonates showed that BBB permeability to both large (70-kDa dextran) and small (3-kDa dextran, Gd-DTPA) tracers remained largely undisturbed 24h after reperfusion. The profoundly different functional integrity of the BBB was associated with the largely nonoverlapping patterns of regulated genes in endothelial cells purified from injured and uninjured adult and neonatal brain at 24h (endothelial transcriptome, 31,042 total probe sets). Within significantly regulated 1,266 probe sets in injured adults and 361 probe sets in neonates, changes in the gene expression of the basal lamina components, adhesion molecules, the tight junction protein occludin, and MMP-9 were among the key differences. The protein expression of collagen-IV, laminin, claudin-5, occludin and ZO-1 was also better preserved in neonatal rats. Neutrophil infiltration remained low in acutely injured neonates but neutralization of CINC-1 in the systemic circulation enhanced neutrophil infiltration, BBB permeability and injury. The markedly more integrant BBB in neonatal brain than in adult brain after acute stroke may have major implications for the treatment of neonatal stroke. PMID:22787045

MMP-9 gene silencing by a Quantum Dot-siRNA nanoplex delivery to maintain the integrity of the blood brain barrier

PubMed Central

Bonoiu, Adela; Mahajan, Supriya D.; Ye, Ling; Kumar, Rajiv; Ding, Hong; Yong, Ken-Tye; Roy, Indrajit; Aalinkeel, Ravikumar; Nair, Bindukumar; Reynolds, Jessica L; Sykes, Donald E; Imperiale, Marco A; Bergey, Earl J.; Schwartz, Stanley A.; Prasad, Paras N.

2009-01-01

The matrix-degrading metalloproteinases (MMPs), particularly MMP-9, are involved in the neuroinflammation processes leading to disrupting of the blood brain barrier (BBB), thereby exacerbating neurological diseases such as HIV-1 AIDS dementia and cerebral ischemia. Nanoparticles have been proposed to act as non-viral gene delivery vectors and have great potential for therapeutic applications in several disease states. In this study, we evaluated the specificity and efficiency of quantum dot (QD) complexed with MMP-9-siRNA (nanoplex) in downregulating the expression of MMP-9 gene in brain microvascular endothelial cells (BMVEC) that constitute the BBB. We hypothesize that silencing MMP-9 gene expression in BMVECs and other cells such as leukocytes may help prevent breakdown of the BBB and inhibit subsequent invasion of the central nervous system (CNS) by infected and inflammatory cells. Our results show that silencing of MMP-9 gene expression resulted in the upregulation of extracellular matrix (ECM) proteins like collagen I, IV, V and a decrease in endothelial permeability, as reflected by reduction of transendothelial resistance across the BBB in a well validated in-vitro BBB model. MMP-9 gene silencing also resulted in an increase in expression of the gene tissue inhibitor of metalloproteinase-1 (TIMP-1). This indicates the importance of a balance between the levels of MMP-9 and its natural inhibitor TIMP-1 in maintaining the basement membrane integrity. These studies promise the application of a novel nanoparticle based siRNA delivery system in modulating the MMP-9 activity in BMVECs and other MMP-9 producing cells. This will prevent neuroinflammation and maintain the integrity of the BBB. PMID:19477169

Cryopreservation of Brain Endothelial Cells Derived from Human Induced Pluripotent Stem Cells Is Enhanced by Rho-Associated Coiled Coil-Containing Kinase Inhibition.

PubMed

Wilson, Hannah K; Faubion, Madeline G; Hjortness, Michael K; Palecek, Sean P; Shusta, Eric V

2016-12-01

The blood-brain barrier (BBB) maintains brain homeostasis but also presents a major obstacle to brain drug delivery. Brain microvascular endothelial cells (BMECs) form the principal barrier and therefore represent the major cellular component of in vitro BBB models. Such models are often used for mechanistic studies of the BBB in health and disease and for drug screening. Recently, human induced pluripotent stem cells (iPSCs) have emerged as a new source for generating BMEC-like cells for use in in vitro human BBB studies. However, the inability to cryopreserve iPSC-BMECs has impeded implementation of this model by requiring a fresh differentiation to generate cells for each experiment. Cryopreservation of differentiated iPSC-BMECs would have a number of distinct advantages, including enabling production of larger scale lots, decreasing lead time to generate purified iPSC-BMEC cultures, and facilitating use of iPSC-BMECs in large-scale screening. In this study, we demonstrate that iPSC-BMECs can be successfully cryopreserved at multiple differentiation stages. Cryopreserved iPSC-BMECs retain high viability, express standard endothelial and BBB markers, and reach a high transendothelial electrical resistance (TEER) of ∼3000 Ω·cm 2 , equivalent to nonfrozen controls. Rho-associated coiled coil-containing kinase (ROCK) inhibitor Y-27632 substantially increased survival and attachment of cryopreserved iPSC-BMECs, as well as stabilized TEER above 800 Ω·cm 2 out to 7 days post-thaw. Overall, cryopreservation will ease handling and storage of high-quality iPSC-BMECs, reducing a key barrier to greater implementation of these cells in modeling the human BBB.

Monitoring Blood-Brain Barrier Integrity Following Amyloid-β Immunotherapy Using Gadolinium-Enhanced MRI in a PDAPP Mouse Model.

PubMed

Blockx, Ines; Einstein, Steve; Guns, Pieter-Jan; Van Audekerke, Johan; Guglielmetti, Caroline; Zago, Wagner; Roose, Dimitri; Verhoye, Marleen; Van der Linden, Annemie; Bard, Frederique

2016-09-06

Amyloid-related imaging abnormalities (ARIA) have been reported with some anti-amyloid-β (Aβ) immunotherapy trials. They are detected with magnetic resonance imaging (MRI) and thought to represent transient accumulation of fluid/edema (ARIA-E) or microhemorrhages (ARIA-H). Although the clinical significance and pathophysiology are unknown, it has been proposed that anti-Aβimmunotherapy may affect blood-brain barrier (BBB) integrity. To examine vascular integrity in aged (12-16 months) PDAPP and wild type mice (WT), we performed a series of longitudinal in vivo MRI studies. Mice were treated on a weekly basis using anti-Aβimmunotherapy (3D6) and follow up was done longitudinally from 1-12 weeks after treatment. BBB-integrity was assessed using both visual assessment of T1-weighted scans and repeated T1 mapping in combination with gadolinium (Gd-DOTA). A subset of 3D6 treated PDAPP mice displayed numerous BBB disruptions, whereas WT and saline-treated PDAPP mice showed intact BBB integrity under the conditions tested. In addition, the contrast induced decrease in T1 value was observed in the meningeal and midline area. BBB disruption events occurred early during treatment (between 1 and 5 weeks), were transient, and resolved quickly. Finally, BBB-leakages associated with microhemorrhages were confirmed by Perls'Prussian blue histopathological analysis. Our preclinical findings support the hypothesis that 3D6 leads to transient leakage from amyloid-positive vessels. The current study has provided valuable insights on the time course of vascular alterations during immunization treatment and supports further research in relation to the nature of ARIA and the utility of in vivo repeated T1 MRI as a translational tool.

Developing Enhanced Blood–Brain Barrier Permeability Models: Integrating External Bio-Assay Data in QSAR Modeling

PubMed Central

Wang, Wenyi; Kim, Marlene T.; Sedykh, Alexander

2015-01-01

Purpose Experimental Blood–Brain Barrier (BBB) permeability models for drug molecules are expensive and time-consuming. As alternative methods, several traditional Quantitative Structure-Activity Relationship (QSAR) models have been developed previously. In this study, we aimed to improve the predictivity of traditional QSAR BBB permeability models by employing relevant public bio-assay data in the modeling process. Methods We compiled a BBB permeability database consisting of 439 unique compounds from various resources. The database was split into a modeling set of 341 compounds and a validation set of 98 compounds. Consensus QSAR modeling workflow was employed on the modeling set to develop various QSAR models. A five-fold cross-validation approach was used to validate the developed models, and the resulting models were used to predict the external validation set compounds. Furthermore, we used previously published membrane transporter models to generate relevant transporter profiles for target compounds. The transporter profiles were used as additional biological descriptors to develop hybrid QSAR BBB models. Results The consensus QSAR models have R2=0.638 for fivefold cross-validation and R2=0.504 for external validation. The consensus model developed by pooling chemical and transporter descriptors showed better predictivity (R2=0.646 for five-fold cross-validation and R2=0.526 for external validation). Moreover, several external bio-assays that correlate with BBB permeability were identified using our automatic profiling tool. Conclusions The BBB permeability models developed in this study can be useful for early evaluation of new compounds (e.g., new drug candidates). The combination of chemical and biological descriptors shows a promising direction to improve the current traditional QSAR models. PMID:25862462

Paracrine signalling of inflammatory cytokines from an in vitro blood brain barrier model upon exposure to polymeric nanoparticles.

PubMed

Raghnaill, Michelle Nic; Bramini, Mattia; Ye, Dong; Couraud, Pierre-Olivier; Romero, Ignacio A; Weksler, Babette; Åberg, Christoffer; Salvati, Anna; Lynch, Iseult; Dawson, Kenneth A

2014-03-07

Nanoparticle properties, such as small size relative to large highly modifiable surface area, offer great promise for neuro-therapeutics and nanodiagnostics. A fundamental understanding and control of how nanoparticles interact with the blood-brain barrier (BBB) could enable major developments in nanomedical treatment of previously intractable neurological disorders, and help ensure that nanoparticles not intended to reach the brain do not cause adverse effects. Nanosafety is of utmost importance to this field. However, a distinct lack of knowledge exists regarding nanoparticle accumulation within the BBB and the biological effects this may induce on neighbouring cells of the Central Nervous System (CNS), particularly in the long-term. This study focussed on the exposure of an in vitro BBB model to model carboxylated polystyrene nanoparticles (PS COOH NPs), as these nanoparticles are well characterised for in vitro experimentation and have been reported as non-toxic in many biological settings. TEM imaging showed accumulation but not degradation of 100 nm PS COOH NPs within the lysosomes of the in vitro BBB over time. Cytokine secretion analysis from the in vitro BBB post 24 h 100 nm PS COOH NP exposure showed a low level of pro-inflammatory RANTES protein secretion compared to control. In contrast, 24 h exposure of the in vitro BBB endothelium to 100 nm PS COOH NPs in the presence of underlying astrocytes caused a significant increase in pro-survival signalling. In conclusion, the tantalising possibilities of nanomedicine must be balanced by cautious studies into the possible long-term toxicity caused by accumulation of known 'toxic' and 'non-toxic' nanoparticles, as general toxicity assays may be disguising significant signalling regulation during long-term accumulation.

Nanotoxicity of poly(n-butylcyano-acrylate) nanoparticles at the blood-brain barrier, in human whole blood and in vivo.

PubMed

Kolter, Marise; Ott, Melanie; Hauer, Christian; Reimold, Isolde; Fricker, Gert

2015-01-10

Therapy of diseases of the central nervous system is a major challenge since drugs have to overcome the blood-brain barrier (BBB). A powerful strategy to enhance cerebral drug concentration is administration of drug-loaded poly(n-butylcyano-acrylate) (PBCA) nanoparticles coated with polysorbate 80 (PS80). This study evaluates the toxicity of PBCA-nanoparticles at the BBB, representing the target organ, the inflammatory response in human whole blood, as the site of administration and in a rat model in vivo. PBCA-nanoparticles were prepared by a mini-emulsion method and characterized concerning size, surface charge, shape and PS80-adsorption. The influence on metabolic activity, cell viability and integrity of the BBB was analyzed in an in vitro model of the BBB. In ex vivo experiments in human whole blood the release of 12 inflammatory cytokines was investigated. In addition, the inflammatory response was studied in vivo in rats and complemented with the analysis of different organ toxicity parameters. PBCA-nanoparticles showed time- and concentration-dependent effects on metabolic activity, cell viability and BBB integrity. No cell death or loss of metabolic activity was observed for nanoparticle-concentrations ≤500μg/ml up to 3h of treatment. Within 12 tested inflammatory cytokines, only interleukin-8 displayed a significant release after nanoparticle exposure in human blood. No severe inflammatory processes or organ damages were identified in rats in vivo. Thus, PBCA-nanoparticles are a promising drug delivery system to overcome the BBB since they showed hardly any cytotoxic or inflammatory effect at therapeutic concentrations and incubation times. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhanced blood-brain barrier transmigration using a novel transferrin embedded fluorescent magneto-liposome nanoformulation

NASA Astrophysics Data System (ADS)

Ding, Hong; Sagar, Vidya; Agudelo, Marisela; Pilakka-Kanthikeel, Sudheesh; Subba Rao Atluri, Venkata; Raymond, Andrea; Samikkannu, Thangavel; Nair, Madhavan P.

2014-02-01

The blood-brain barrier (BBB) is considered as the primary impediment barrier for most drugs. Delivering therapeutic agents to the brain is still a big challenge to date. In our study, a dual mechanism, receptor mediation combined with external non-invasive magnetic force, was incorporated into ferrous magnet-based liposomes for BBB transmigration enhancement. The homogenous magnetic nanoparticles (MNPs), with a size of ˜10 nm, were synthesized and confirmed by TEM and XRD respectively. The classical magnetism assay showed the presence of the characteristic superparamagnetic property. These MNPs encapsulated in PEGylated fluorescent liposomes as magneto-liposomes (MLs) showed mono-dispersion, ˜130 ± 10 nm diameter, by dynamic laser scattering (DLS) using the lipid-extrusion technique. Remarkably, a magnetite encapsulation efficiency of nearly 60% was achieved. Moreover, the luminescence and hydrodynamic size of the MLs was stable for over two months at 4 ° C. Additionally, the integrity of the ML structure remained unaffected through 120 rounds of circulation mimicking human blood fluid. After biocompatibility confirmation by cytotoxicity evaluation, these fluorescent MLs were further embedded with transferrin and applied to an in vitro BBB transmigration study in the presence or absence of external magnetic force. Comparing with magnetic force- or transferrin receptor-mediated transportation alone, their synergy resulted in 50-100% increased transmigration without affecting the BBB integrity. Consequently, confocal microscopy and iron concentration in BBB-composed cells further confirmed the higher cellular uptake of ML particles due to the synergic effect. Thus, our multifunctional liposomal magnetic nanocarriers possess great potential in particle transmigration across the BBB and may have a bright future in drug delivery to the brain.

Enhanced blood-brain barrier transmigration using a novel transferrin embedded fluorescent magneto-liposome nanoformulation.

PubMed

Ding, Hong; Sagar, Vidya; Agudelo, Marisela; Pilakka-Kanthikeel, Sudheesh; Atluri, Venkata Subba Rao; Raymond, Andrea; Samikkannu, Thangavel; Nair, Madhavan P

2014-02-07

The blood-brain barrier (BBB) is considered as the primary impediment barrier for most drugs. Delivering therapeutic agents to the brain is still a big challenge to date. In our study, a dual mechanism, receptor mediation combined with external non-invasive magnetic force, was incorporated into ferrous magnet-based liposomes for BBB transmigration enhancement. The homogenous magnetic nanoparticles (MNPs), with a size of ∼10 nm, were synthesized and confirmed by TEM and XRD respectively. The classical magnetism assay showed the presence of the characteristic superparamagnetic property. These MNPs encapsulated in PEGylated fluorescent liposomes as magneto-liposomes (MLs) showed mono-dispersion, ∼130 ± 10 nm diameter, by dynamic laser scattering (DLS) using the lipid-extrusion technique. Remarkably, a magnetite encapsulation efficiency of nearly 60% was achieved. Moreover, the luminescence and hydrodynamic size of the MLs was stable for over two months at 4 ° C. Additionally, the integrity of the ML structure remained unaffected through 120 rounds of circulation mimicking human blood fluid. After biocompatibility confirmation by cytotoxicity evaluation, these fluorescent MLs were further embedded with transferrin and applied to an in vitro BBB transmigration study in the presence or absence of external magnetic force. Comparing with magnetic force- or transferrin receptor-mediated transportation alone, their synergy resulted in 50-100% increased transmigration without affecting the BBB integrity. Consequently, confocal microscopy and iron concentration in BBB-composed cells further confirmed the higher cellular uptake of ML particles due to the synergic effect. Thus, our multifunctional liposomal magnetic nanocarriers possess great potential in particle transmigration across the BBB and may have a bright future in drug delivery to the brain.

Regulation of immune cell infiltration into the CNS by regional neural inputs explained by the gate theory.

PubMed

Arima, Yasunobu; Kamimura, Daisuke; Sabharwal, Lavannya; Yamada, Moe; Bando, Hidenori; Ogura, Hideki; Atsumi, Toru; Murakami, Masaaki

2013-01-01

The central nervous system (CNS) is an immune-privileged environment protected by the blood-brain barrier (BBB), which consists of specific endothelial cells that are brought together by tight junctions and tight liner sheets formed by pericytes and astrocytic end-feet. Despite the BBB, various immune and tumor cells can infiltrate the CNS parenchyma, as seen in several autoimmune diseases like multiple sclerosis (MS), cancer metastasis, and virus infections. Aside from a mechanical disruption of the BBB like trauma, how and where these cells enter and accumulate in the CNS from the blood is a matter of debate. Recently, using experimental autoimmune encephalomyelitis (EAE), an animal model of MS, we found a "gateway" at the fifth lumber cord where pathogenic autoreactive CD4+ T cells can cross the BBB. Interestingly, this gateway is regulated by regional neural stimulations that can be mechanistically explained by the gate theory. In this review, we also discuss this theory and its potential for treating human diseases.

A choline derivate-modified nanoprobe for glioma diagnosis using MRI

NASA Astrophysics Data System (ADS)

Li, Jianfeng; Huang, Shixian; Shao, Kun; Liu, Yang; An, Sai; Kuang, Yuyang; Guo, Yubo; Ma, Haojun; Wang, Xuxia; Jiang, Chen

2013-04-01

Gadolinium (Gd) chelate contrast-enhanced magnetic resonance imaging (MRI) is a preferred method of glioma detection and preoperative localisation because it offers high spatial resolution and non-invasive deep tissue penetration. Gd-based contrast agents, such as Gd-diethyltriaminepentaacetic acid (DTPA-Gd, Magnevist), are widely used clinically for tumor diagnosis. However, the Gd-based MRI approach is limited for patients with glioma who have an uncompromised blood-brain barrier (BBB). Moreover, the rapid renal clearance and non-specificity of such contrast agents further hinders their prevalence. We present a choline derivate (CD)-modified nanoprobe with BBB permeability, glioma specificity and a long blood half-life. Specific accumulation of the nanoprobe in gliomas and subsequent MRI contrast enhancement are demonstrated in vitro in U87 MG cells and in vivo in a xenograft nude model. BBB and glioma dual targeting by this nanoprobe may facilitate precise detection of gliomas with an uncompromised BBB and may offer better preoperative and intraoperative tumor localization.

Current State and Future Perspectives in QSAR Models to Predict Blood- Brain Barrier Penetration in Central Nervous System Drug R&D.

PubMed

Morales, Juan F; Montoto, Sebastian Scioli; Fagiolino, Pietro; Ruiz, Maria E

2017-01-01

The Blood-Brain Barrier (BBB) is a physical and biochemical barrier that restricts the entry of certain drugs to the Central Nervous System (CNS), while allowing the passage of others. The ability to predict the permeability of a given molecule through the BBB is a key aspect in CNS drug discovery and development, since neurotherapeutic agents with molecular targets in the CNS should be able to cross the BBB, whereas peripherally acting agents should not, to minimize the risk of CNS adverse effects. In this review we examine and discuss QSAR approaches and current availability of experimental data for the construction of BBB permeability predictive models, focusing on the modeling of the biorelevant parameter unbound partitioning coefficient (Kp,uu). Emphasis is made on two possible strategies to overcome the current limitations of in silico models: considering the prediction of brain penetration as a multifactorial problem, and increasing experimental datasets through accurate and standardized experimental techniques.

Social stress induces neurovascular pathology promoting depression

PubMed Central

Menard, Caroline; Pfau, Madeline L.; Hodes, Georgia E.; Kana, Veronika; Wang, Victoria X.; Bouchard, Sylvain; Takahashi, Aki; Flanigan, Meghan E.; Aleyasin, Hossein; LeClair, Katherine B.; Janssen, William G.; Labonté, Benoit; Parise, Eric M.; Lorsch, Zachary S.; Golden, Sam A.; Heshmati, Mitra; Tamminga, Carol; Turecki, Gustavo; Campbell, Matthew; Fayad, Zahi; Tang, Cheuk Ying; Merad, Miriam; Russo, Scott J.

2017-01-01

Studies suggest that heightened peripheral inflammation contributes to the pathogenesis of major depressive disorder. We investigated the effect of chronic social defeat stress, a mouse model of depression, on blood-brain barrier (BBB) permeability and infiltration of peripheral immune signals. We found reduced expression of endothelial cell tight junction protein claudin-5 (cldn5) and abnormal blood vessel morphology in nucleus accumbens (NAc) of stress-susceptible but not resilient mice. CLDN5 expression was also decreased in NAc of depressed patients. Cldn5 down-regulation was sufficient to induce depression-like behaviors following subthreshold social stress while chronic antidepressant treatment rescued cldn5 loss and promoted resilience. Reduced BBB integrity in NAc of stress-susceptible or AAV-shRNA-cldn5-injected mice caused infiltration of peripheral cytokine interleukin-6 (IL-6) into brain parenchyma and subsequent expression of depression-like behaviors. These findings suggest that chronic social stress alters BBB integrity through loss of tight junction protein cldn5, promoting peripheral IL-6 passage across the BBB and depression. PMID:29184215

The effect of nanoparticle size on the ability to cross the blood-brain barrier: an in vivo study.

PubMed

Betzer, Oshra; Shilo, Malka; Opochinsky, Renana; Barnoy, Eran; Motiei, Menachem; Okun, Eitan; Yadid, Gal; Popovtzer, Rachela

2017-07-01

Our goal was to develop an efficient nanoparticle-based system that can overcome the restrictive mechanism of the blood-brain barrier (BBB) by targeting insulin receptors and would thus enable drug delivery to the brain. Insulin-coated gold nanoparticles (INS-GNPs) were synthesized to serve as a BBB transport system. The effect of nanoparticle size (20, 50 and 70 nm) on their ability to cross the BBB was quantitatively investigated in Balb/C mice. The most widespread biodistribution and highest accumulation within the brain were observed using 20 nm INS-GNPs, 2 h post injection. In vivo CT imaging revealed that particles migrated to specific brain regions, which are involved in neurodegenerative and neuropsychiatric disorders. These findings promote the optimization of nanovehicles for transport of drugs through the BBB. The insulin coating of the particles enabled targeting of specific brain regions, suggesting the potential use of INS-GNPs for delivery of various treatments for brain-related disorders.

Hormones and the blood-brain barrier.

PubMed

Hampl, Richard; Bičíková, Marie; Sosvorová, Lucie

2015-03-01

Hormones exert many actions in the brain, and brain cells are also hormonally active. To reach their targets in brain structures, hormones must overcome the blood-brain barrier (BBB). The BBB is a unique device selecting desired/undesired molecules to reach or leave the brain, and it is composed of endothelial cells forming the brain vasculature. These cells differ from other endothelial cells in their almost impermeable tight junctions and in possessing several membrane structures such as receptors, transporters, and metabolically active molecules, ensuring their selection function. The main ways how compounds pass through the BBB are briefly outlined in this review. The main part concerns the transport of major classes of hormones: steroids, including neurosteroids, thyroid hormones, insulin, and other peptide hormones regulating energy homeostasis, growth hormone, and also various cytokines. Peptide transporters mediating the saturable transport of individual classes of hormones are reviewed. The last paragraph provides examples of how hormones affect the permeability and function of the BBB either at the level of tight junctions or by various transporters.

Uptake and transcytosis of functionalized superparamagnetic iron oxide nanoparticles in an in vitro blood brain barrier model.

PubMed

Ivask, Angela; Pilkington, Emily H; Blin, Thomas; Käkinen, Aleksandr; Vija, Heiki; Visnapuu, Meeri; Quinn, John F; Whittaker, Michael R; Qiao, Ruirui; Davis, Thomas P; Ke, Pu Chun; Voelcker, Nicolas H

2018-01-30

Two major hurdles in nanomedicine are the limited strategies for synthesizing stealth nanoparticles and the poor efficacy of the nanoparticles in translocating across the blood brain barrier (BBB). Here we examined the uptake and transcytosis of iron oxide nanoparticles (IONPs) grafted with biomimetic phosphorylcholine (PC) brushes in an in vitro BBB model system, and compared them with bare, PEG or PC-PEG mixture grafted IONPs. Hyperspectral imaging indicated IONP co-localization with cells. Quantitative analysis with total reflection X-ray fluorescence spectrometry showed that after 24 h, 78% of PC grafted, 68-69% of PEG or PC-PEG grafted, and 30% of bare IONPs were taken up by the BBB. Transcytosis of IONPs was time-dependent and after 24 h, 16-17% of PC or PC-PEG mixture grafted IONPs had passed the BBB model, significantly more than PEG grafted or bare IONPs. These findings point out that grafting of IONPs with PC is a viable strategy for improving the uptake and transcytosis of nanoparticles.

Oral erlotinib, but not rapamycin, causes modest acceleration of bladder and hindlimb recovery from spinal cord injury in rats.

PubMed

Kjell, J; Pernold, K; Olson, L; Abrams, M B

2014-03-01

Erlotinib and Rapamycin are both in clinical use and experimental inhibition of their respective molecular targets, EGFR and mTORC1, has improved recovery from spinal cord injury. Our aim was to determine if daily Erlotinib or Rapamycin treatment started directly after spinal contusion injury in rats improves locomotion function or recovery of bladder function. Stockholm, Sweden. Rats were subjected to contusion injuries and treated during the acute phase with either Erlotinib or Rapamycin. Recovery of bladder function was monitored by measuring residual urine volume and hindlimb locomotion assessed by open-field observations using the BBB rating scale as well as by automated registration of gait parameters. Body weights were monitored. To determine whether Erlotinib and Rapamycin inhibit the same signaling pathway, a cell culture system and western blots were used. Erlotinib accelerated locomotor recovery and slightly improved bladder recovery; however, we found no long-term improvements of locomotor function. Rapamycin did neither improved locomotor function nor bladder recovery. In vitro studies confirmed that Erlotinib and Rapamycin both inhibit the EGFR-mTORC1 signaling pathway. We conclude that none of these two drug regimes improved long-term functional outcome in our current model of spinal cord injury. Nevertheless, oral treatment with Erlotinib may offer modest temporary advantages, whereas treatment with Rapamycin does not.

Lipopolysaccharide-induced blood-brain barrier disruption: roles of cyclooxygenase, oxidative stress, neuroinflammation, and elements of the neurovascular unit.

PubMed

Banks, William A; Gray, Alicia M; Erickson, Michelle A; Salameh, Therese S; Damodarasamy, Mamatha; Sheibani, Nader; Meabon, James S; Wing, Emily E; Morofuji, Yoichi; Cook, David G; Reed, May J

2015-11-25

Disruption of the blood-brain barrier (BBB) occurs in many diseases and is often mediated by inflammatory and neuroimmune mechanisms. Inflammation is well established as a cause of BBB disruption, but many mechanistic questions remain. We used lipopolysaccharide (LPS) to induce inflammation and BBB disruption in mice. BBB disruption was measured using (14)C-sucrose and radioactively labeled albumin. Brain cytokine responses were measured using multiplex technology and dependence on cyclooxygenase (COX) and oxidative stress determined by treatments with indomethacin and N-acetylcysteine. Astrocyte and microglia/macrophage responses were measured using brain immunohistochemistry. In vitro studies used Transwell cultures of primary brain endothelial cells co- or tri-cultured with astrocytes and pericytes to measure effects of LPS on transendothelial electrical resistance (TEER), cellular distribution of tight junction proteins, and permeability to (14)C-sucrose and radioactive albumin. In comparison to LPS-induced weight loss, the BBB was relatively resistant to LPS-induced disruption. Disruption occurred only with the highest dose of LPS and was most evident in the frontal cortex, thalamus, pons-medulla, and cerebellum with no disruption in the hypothalamus. The in vitro and in vivo patterns of LPS-induced disruption as measured with (14)C-sucrose, radioactive albumin, and TEER suggested involvement of both paracellular and transcytotic pathways. Disruption as measured with albumin and (14)C-sucrose, but not TEER, was blocked by indomethacin. N-acetylcysteine did not affect disruption. In vivo, the measures of neuroinflammation induced by LPS were mainly not reversed by indomethacin. In vitro, the effects on LPS and indomethacin were not altered when brain endothelial cells (BECs) were cultured with astrocytes or pericytes. The BBB is relatively resistant to LPS-induced disruption with some brain regions more vulnerable than others. LPS-induced disruption appears is to be dependent on COX but not on oxidative stress. Based on in vivo and in vitro measures of neuroinflammation, it appears that astrocytes, microglia/macrophages, and pericytes play little role in the LPS-mediated disruption of the BBB.

Alzheimer's disease-like impaired cognition in endothelial-specific megalin-null mice.

PubMed

Dietrich, Marcelo; Antequera, Desiree; Pascual, Consuelo; Castro, Nerea; Bolos, Marta; Carro, Eva

2014-01-01

Megalin has been suggested to be involved in Alzheimer's disease (AD), mediating blood-brain barrier (BBB) transport of multiple ligands, including amyloid-β peptide (Aβ), but also neuroprotective factors. Because no transgenic model is currently available to study this concept, we have obtained transgenic mice blocking megalin expression at the BBB. These endothelial megalin deficient (EMD) mice developed increased anxiety behavior and impaired learning ability and recognition memory, similar to symptoms described in AD. Degenerating neurons were also observed in the cerebral cortex of EMD mice. In view of our findings we suggest that, in mice, megalin deficiency at the BBB leads to neurodegeneration.

Nanoparticle transport across the blood brain barrier.

PubMed

Grabrucker, Andreas M; Ruozi, Barbara; Belletti, Daniela; Pederzoli, Francesca; Forni, Flavio; Vandelli, Maria Angela; Tosi, Giovanni

2016-01-01

While the role of the blood-brain barrier (BBB) is increasingly recognized in the (development of treatments targeting neurodegenerative disorders, to date, few strategies exist that enable drug delivery of non-BBB crossing molecules directly to their site of action, the brain. However, the recent advent of Nanomedicines may provide a potent tool to implement CNS targeted delivery of active compounds. Approaches for BBB crossing are deeply investigated in relation to the pathology: among the main important diseases of the CNS, this review focuses on the application of nanomedicines to neurodegenerative disorders (Alzheimer, Parkinson and Huntington's Disease) and to other brain pathologies as epilepsy, infectious diseases, multiple sclerosis, lysosomal storage disorders, strokes.

Targeted drug delivery to the brain using magnetic nanoparticles.

PubMed

Thomsen, Louiza Bohn; Thomsen, Maj Schneider; Moos, Torben

2015-01-01

Brain capillary endothelial cells denote the blood-brain barrier (BBB), and conjugation of nanoparticles with antibodies that target molecules expressed by these endothelial cells may facilitate their uptake and transport into the brain. Magnetic nanoparticles can be encapsulated in liposomes and carry large molecules with therapeutic potential, for example, siRNA, cDNA and polypeptides. An additional approach to enhance the transport of magnetic nanoparticles across the BBB is the application of extracranially applied magnetic force. Stepwise targeting of magnetic nanoparticles to brain capillary endothelial cells followed by transport through the BBB using magnetic force may prove a novel mechanism for targeted therapy of macromolecules to the brain.

Increased miR-21-3p in injured brain microvascular endothelial cells following traumatic brain injury aggravates blood-brain barrier damage by promoting cellular apoptosis and inflammation through targeting MAT2B.

PubMed

Ge, Xintong; Li, Wenzhu; Huang, Shan; Yin, Zhenyu; Yang, Mengchen; Han, Zhenying; Han, Zhaoli; Chen, Fanglian; Wang, Haichen; Lei, Ping; Zhang, Jian-Ning

2018-04-26

Our recent papers have reported that increased miR-21-5p in brain following traumatic brain injury (TBI) could improve the neurological outcome through alleviating blood-brain barrier (BBB) damage. miR-21-3p is another mature miRNA derived from pre-miR-21 after Dicer Procession other than miR-21-5p. Its roles in various diseases, such as tumors and myocardial disease aroused great interest for research in recent years. To further explore the function and underlying mechanism of miR-21, especially miR-21-3p in regulating the pathological development of BBB damage after TBI, we designed this research and focused on studying the impact of miR-21-3p on apoptosis and inflammation in brain microvascular endothelial cells (BMVECs), the major cellular component of BBB. We performed controlled cortical impact on mouse brain, and employed the oxygen glucose deprivation/reoxygenation (OGD)-treated bEnd.3 cells injury model. We found that miR-21-3p level in BMVECs from injured cerebral cortex of controlled cortical impact (CCI) mice, and bEnd.3 cells with OGD treatment were both increased after injury. For in-vitro experiments, downregulation on miR-21-3p level by transfecting miR-21-3p antagomir in cultured cells alleviated OGD-induced BBB damage, characterized by decreased BBB leakage and increased expression of tight junction proteins. Besides, miR-21-3p antagomir could suppress cell death by anti-apoptosis, and control inflammatory response by inhibiting the activity of NF-κB signaling. Using luciferase reporter assay and a MAT2B-silenced shRNA vector, we further proved that miR-21-3p exerted above functions through targeting MAT2B. In addition, in-vivo experiments also confirmed that intracerebroventricular infusion of miR-21-3p antagomir could alleviate BBB leakage after TBI. It reduced Evans Blue extravasation and promoted the expression of tight junction proteins, thus contributed to improve the neurological outcome of CCI mice. Taken together, increased miR-21-3p in BMVECs after TBI was bad for restoration of injured BBB. Downregulation on miR-21-3p level in injured brain could be a promising therapeutic strategy for BBB damage after TBI.

Effect of surface charge of immortalized mouse cerebral endothelial cell monolayer on transport of charged solutes.

PubMed

Yuan, Wei; Li, Guanglei; Gil, Eun Seok; Lowe, Tao Lu; Fu, Bingmei M

2010-04-01

Charge carried by the surface glycocalyx layer (SGL) of the cerebral endothelium has been shown to significantly modulate the permeability of the blood-brain barrier (BBB) to charged solutes in vivo. The cultured monolayer of bEnd3, an immortalized mouse cerebral endothelial cell line, is becoming a popular in vitro BBB model due to its easy growth and maintenance of many BBB characteristics over repeated passages. To test whether the SGL of bEnd3 monolayer carries similar charge as that in the intact BBB and quantify this charge, which can be characterized by the SGL thickness (L(f)) and charge density (C(mf)), we measured the solute permeability of bEnd3 monolayer to neutral solutes and to solutes with similar size but opposite charges: negatively charged alpha-lactalbumin (-11) and positively charged ribonuclease (+3). Combining the measured permeability data with a transport model across the cell monolayer, we predicted the L(f) and the C(mf) of bEnd3 monolayer, which is approximately 160 nm and approximately 25 mEq/L, respectively. We also investigated whether orosomucoid, a plasma glycoprotein modulating the charge of the intact BBB, alters the charge of bEnd3 monolayer. We found that 1 mg/mL orosomucoid would increase SGL charge density of bEnd3 monolayer to approximately 2-fold of its control value.

JAM-A and ALCAM are therapeutic targets to inhibit diapedesis across the BBB of CD14+CD16+ monocytes in HIV-infected individuals.

PubMed

Williams, Dionna W; Anastos, Kathryn; Morgello, Susan; Berman, Joan W

2015-02-01

Monocyte transmigration across the BBB is a critical step in the development of cognitive deficits termed HAND that affect 40-70% of HIV-infected individuals, even with successful antiretroviral therapy. The monocyte subsets that enter the CNS during HIV infection are not fully characterized. We examined PBMC from HIV-positive individuals from 2 distinct cohorts and enumerated monocyte populations, characterized their transmigration properties across an in vitro human BBB model, and identified surface proteins critical for the entry of these cells into the CNS. We demonstrated that the frequency of peripheral blood CD14(+)CD16(+) and CD14(low)CD16(+) monocytes was increased in HIV-seropositive compared with -seronegative individuals, despite virologic control. We showed that CD14(+)CD16(+) monocytes selectively transmigrated across our BBB model as a result of their increased JAM-A and ALCAM expression. Antibody blocking of these proteins inhibited diapedesis of CD14(+)CD16(+) monocytes but not of T cells from the same HIV-infected people across the BBB. Our data indicate that JAM-A and ALCAM are therapeutic targets to decrease the entry of CD14(+)CD16(+) monocytes into the CNS of HIV-seropositive individuals, contributing to the eradication of neuroinflammation, HAND, and CNS viral reservoirs. © Society for Leukocyte Biology.

Cell-penetrating anti-GFAP VHH and corresponding fluorescent fusion protein VHH-GFP spontaneously cross the blood-brain barrier and specifically recognize astrocytes: application to brain imaging.

PubMed

Li, Tengfei; Bourgeois, Jean-Pierre; Celli, Susanna; Glacial, Fabienne; Le Sourd, Anne-Marie; Mecheri, Salah; Weksler, Babette; Romero, Ignacio; Couraud, Pierre-Olivier; Rougeon, François; Lafaye, Pierre

2012-10-01

Antibodies normally do not cross the blood-brain barrier (BBB) and cannot bind an intracellular cerebral antigen. We demonstrate here for the first time that a new class of antibodies can cross the BBB without treatment. Camelids produce native homodimeric heavy-chain antibodies, the paratope being composed of a single-variable domain called VHH. Here, we used recombinant VHH directed against human glial fibrillary acidic protein (GFAP), a specific marker of astrocytes. Only basic VHHs (e.g., pI=9.4) were able to cross the BBB in vitro (7.8 vs. 0% for VHH with pI=7.7). By intracarotid and intravenous injections into live mice, we showed that these basic VHHs are able to cross the BBB in vivo, diffuse into the brain tissue, penetrate into astrocytes, and specifically label GFAP. To analyze their ability to be used as a specific transporter, we then expressed a recombinant fusion protein VHH-green fluorescent protein (GFP). These "fluobodies" specifically labeled GFAP on murine brain sections, and a basic variant (pI=9.3) of the fusion protein VHH-GFP was able to cross the BBB and to label astrocytes in vivo. The potential of VHHs as diagnostic or therapeutic agents in the central nervous system now deserves attention.

Hydrogen inhalation ameliorated mast cell mediated brain injury after ICH in mice

PubMed Central

Manaenko, Anatol; Lekic, Tim; Ma, Qingyi; Zhang, John H.; Tang, Jiping

2012-01-01

OBJECTIVE Hydrogen inhalation was neuroprotective in several brain injury models. Its mechanisms are believed to be related to anti-oxidative stress. We investigated the potential neurovascular protective effect of hydrogen inhalation especially effect on mast cell activation in a mouse model of intracerebral hemorrhage (ICH). DESIGN Controlled in vivo laboratory study. SETTING Animal research laboratory SUBJECTS 171, 8 weeks old male CD-1 mice were used. INTERVENTIONS Collagenase-induced ICH model in 8 weeks old, male, CD-1 mice was used. Hydrogen was administrated via spontaneous inhalation. The blood-brain barrier (BBB) permeability and neurological deficits were investigated at 24 and 72 hours after ICH. Mast cell activation was evaluated by Western blot and immuno-staining. The effects of hydrogen inhalation on mast cell activation were confirmed in an autologous blood injection model ICH. MEASURMENT AND MAIN RESULTS At 24 and 72 hours post-ICH, animals showed BBB disruption, brain edema, neurological deficits, accompanied with phosphorylation of Lyn kinase and release of tryptase, indicating mast cell activation. Hydrogen treatment diminished phosphorylation of Lyn kinase and release of tryptase, decreased accumulation and degranulation of mast cells, attenuated BBB disruption and improved neurobehavioral function. CONCLUSION Activation of mast cells following ICH contributed to increase of BBB permeability and brain edema. Hydrogen inhalation preserved BBB disruption by prevention of mast cell activation after ICH. PMID:23388512

Specific Binding, Uptake, and Transport of ICAM-1-Targeted Nanocarriers Across Endothelial and Subendothelial Cell Components of the Blood-Brain Barrier

PubMed Central

Hsu, Janet; Rappaport, Jeff; Muro, Silvia

2014-01-01

Purpose The blood-brain barrier (BBB) represents a target for therapeutic intervention and an obstacle for brain drug delivery. Targeting endocytic receptors on brain endothelial cells (ECs) helps transporting drugs and carriers into and across this barrier. While most receptors tested are associated with clathrin-mediated pathways, clathrin-independent routes are rather unexplored. We have examined the potential for one of these pathways, cell adhesion molecule (CAM)-mediated endocytosis induced by targeting intercellular adhesion molecule 1 (ICAM-1), to transport drug carriers into and across BBB models. Methods Model polymer nanocarriers (NCs) coated with control IgG or antibodies against ICAM-1 (IgG NCs vs. anti-ICAM NCs; ~250-nm) were incubated with human brain ECs, astrocytes (ACs), or pericytes (PCs) grown as monocultures or bilayered (endothelial+subendothelial) co-cultures. Results ICAM-1 was present and overexpressed in disease-like conditions on ECs and, at a lesser extent, on ACs and PCs which are BBB subendothelial components. Specific targeting and CAM-mediated uptake of anti-ICAM NCs occurred in these cells, although this was greater for ECs. Anti-ICAM NCs were transported across endothelial monolayers and endothelial+subendothelial co-cultures modeling the BBB. Conclusions CAM-mediated transport induced by ICAM-1 targeting operates in endothelial and subendothelial cellular components of the BBB, which may provide an avenue to overcome this barrier. PMID:24558007

Routes for Drug Translocation Across the Blood-Brain Barrier: Exploiting Peptides as Delivery Vectors.

PubMed

Kristensen, Mie; Brodin, Birger

2017-09-01

A number of potent drugs for the treatment of brain diseases are available. However, in order for them to reach their target site of action, they must pass the blood-brain barrier (BBB). The capillary endothelium comprises the major barrier of the BBB and allows only passive permeation of some small lipophilic molecules. Brain delivery of the larger biopharmaceuticals, which today includes an increasing number of novel drug entities, is therefore restricted, both due to their molecular size and their hydrophilic nature. Thus, the development of novel drug entities intended for the treatment of brain diseases such as neurodegenerative diseases or brain cancers require a delivery strategy for overcoming the BBB before reaching its final target within the brain. Peptide-based delivery vector is an emerging tool as shuttles for drug delivery across the BBB and one may explore receptor-mediated transcytosis, adsorptive-mediated transcytosis, and the paracellular route. The latter, however, being controversial due to the risk of co-delivery of blood-borne potential harmful substances. On the other hand, a number of studies report on drug delivery across the BBB exploiting receptor-mediated transcytosis and adsorptive-mediated transcytosis, indicating that peptides and peptide vectors may be of use in a central nervous system delivery context. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Blood-Brain Barrier Integrity and Glial Support: Mechanisms that can be targeted for Novel Therapeutic Approaches in Stroke

PubMed Central

Ronaldson, Patrick T.; Davis, Thomas P.

2014-01-01

The blood-brain barrier (BBB) is a critical regulator of CNS homeostasis. Additionally, the BBB is the most significant obstacle to effective CNS drug delivery. It possesses specific charcteristics (i.e., tight junction protein complexes, influx and efflux transporters) that control permeation of circulating solutes including therapeutic agents. In order to form this “barrier,” brain microvascular endothelial cells require support of adjacent astrocytes and microglia. This intricate relationship also occurs between endothelial cells and other cell types and structures of the CNS (i.e., pericytes, neurons, extracellular matrix), which implies existence of a “neurovascular unit.” Ischemic stroke can disrupt the neurovascular unit at both the structural and functional level, which leads to an increase in leak across the BBB. Recent studies have identified several pathophysiological mechanisms (i.e., oxidative stress, activation of cytokine-mediated intracellular signaling systems) that mediate changes in the neurovascular unit during ischemic stroke. This review summarizes current knowledge in this area and emphasizes pathways (i.e., oxidative stress, cytokine-mediated intracellular signaling, glial-expressed receptors/targets) that can be manipulated pharmacologically for i) preservation of BBB and glial integrity during ischemic stroke and ii) control of drug permeation and/or transport across the BBB in an effort to identify novel targets for optimization of CNS delivery of therapeutics in the setting of ischemic stroke. PMID:22574987

Crossing the Blood-Brain Barrier: Recent Advances in Drug Delivery to the Brain.

PubMed

Patel, Mayur M; Patel, Bhoomika M

2017-02-01

CNS disorders are on the rise despite advancements in our understanding of their pathophysiological mechanisms. A major hurdle to the treatment of these disorders is the blood-brain barrier (BBB), which serves as an arduous janitor to protect the brain. Many drugs are being discovered for CNS disorders, which, however fail to enter the market because of their inability to cross the BBB. This is a pronounced challenge for the pharmaceutical fraternity. Hence, in addition to the discovery of novel entities and drug candidates, scientists are also developing new formulations of existing drugs for brain targeting. Several approaches have been investigated to allow therapeutics to cross the BBB. As the molecular structure of the BBB is better elucidated, several key approaches for brain targeting include physiological transport mechanisms such as adsorptive-mediated transcytosis, inhibition of active efflux pumps, receptor-mediated transport, cell-mediated endocytosis, and the use of peptide vectors. Drug-delivery approaches comprise delivery from microspheres, biodegradable wafers, and colloidal drug-carrier systems (e.g., liposomes, nanoparticles, nanogels, dendrimers, micelles, nanoemulsions, polymersomes, exosomes, and quantum dots). The current review discusses the latest advancements in these approaches, with a major focus on articles published in 2015 and 2016. In addition, we also cover the alternative delivery routes, such as intranasal and convection-enhanced diffusion methods, and disruption of the BBB for brain targeting.

Specific binding, uptake, and transport of ICAM-1-targeted nanocarriers across endothelial and subendothelial cell components of the blood-brain barrier.

PubMed

Hsu, Janet; Rappaport, Jeff; Muro, Silvia

2014-07-01

The blood-brain barrier (BBB) represents a target for therapeutic intervention and an obstacle for brain drug delivery. Targeting endocytic receptors on brain endothelial cells (ECs) helps transport drugs and carriers into and across this barrier. While most receptors tested are associated with clathrin-mediated pathways, clathrin-independent routes are rather unexplored. We have examined the potential for one of these pathways, cell adhesion molecule (CAM)-mediated endocytosis induced by targeting intercellular adhesion molecule -1 (ICAM-1), to transport drug carriers into and across BBB models. Model polymer nanocarriers (NCs) coated with control IgG or antibodies against ICAM-1 (IgG NCs vs. anti-ICAM NCs; ~250-nm) were incubated with human brain ECs, astrocytes (ACs), or pericytes (PCs) grown as monocultures or bilayered (endothelial+subendothelial) co-cultures. ICAM-1 was present and overexpressed in disease-like conditions on ECs and, at a lesser extent, on ACs and PCs which are BBB subendothelial components. Specific targeting and CAM-mediated uptake of anti-ICAM NCs occurred in these cells, although this was greater for ECs. Anti-ICAM NCs were transported across endothelial monolayers and endothelial+subendothelial co-cultures modeling the BBB. CAM-mediated transport induced by ICAM-1 targeting operates in endothelial and subendothelial cellular components of the BBB, which may provide an avenue to overcome this barrier.

Serum-borne bioactivity caused by pulmonary multiwalled carbon nanotubes induces neuroinflammation via blood-brain barrier impairment.

PubMed

Aragon, Mario J; Topper, Lauren; Tyler, Christina R; Sanchez, Bethany; Zychowski, Katherine; Young, Tamara; Herbert, Guy; Hall, Pamela; Erdely, Aaron; Eye, Tracy; Bishop, Lindsey; Saunders, Samantha A; Muldoon, Pretal P; Ottens, Andrew K; Campen, Matthew J

2017-03-07

Pulmonary exposure to multiwalled carbon nanotubes (MWCNTs) causes indirect systemic inflammation through unknown pathways. MWCNTs translocate only minimally from the lungs into the systemic circulation, suggesting that extrapulmonary toxicity may be caused indirectly by lung-derived factors entering the circulation. To assess a role for MWCNT-induced circulating factors in driving neuroinflammatory outcomes, mice were acutely exposed to MWCNTs (10 or 40 µg/mouse) via oropharyngeal aspiration. At 4 h after MWCNT exposure, broad disruption of the blood-brain barrier (BBB) was observed across the capillary bed with the small molecule fluorescein, concomitant with reactive astrocytosis. However, pronounced BBB permeation was noted, with frank albumin leakage around larger vessels (>10 µm), overlain by a dose-dependent astroglial scar-like formation and recruitment of phagocytic microglia. As affirmed by elevated inflammatory marker transcription, MWCNT-induced BBB disruption and neuroinflammation were abrogated by pretreatment with the rho kinase inhibitor fasudil. Serum from MWCNT-exposed mice induced expression of adhesion molecules in primary murine cerebrovascular endothelial cells and, in a wound-healing in vitro assay, impaired cell motility and cytokinesis. Serum thrombospondin-1 level was significantly increased after MWCNT exposure, and mice lacking the endogenous receptor CD36 were protected from the neuroinflammatory and BBB permeability effects of MWCNTs. In conclusion, acute pulmonary exposure to MWCNTs causes neuroinflammatory responses that are dependent on the disruption of BBB integrity.

Glioma targeted delivery strategy of doxorubicin-loaded liposomes by dual-ligand modification.

PubMed

Han, Wei; Yin, Guangfu; Pu, Ximing; Chen, Xianchun; Liao, Xiaoming; Huang, Zhongbing

2017-10-01

The blood-brain barrier (BBB) is the protective parclose of brain safety, but it is also the main obstacle of the drug delivery to cerebral parenchyma, which hamper therapy for brain diseases. In this work, a glioma targeted drug delivery system was developed through loading doxorubicin into Angiopep-2 and TAT peptide dual-modified liposomes (DOX-TAT-Ang-LIP). Low-density lipoprotein receptor-related protein-1 (LRP1) was one receptor overexpressed on both BBB and glioma cytomembranes. Angiopep-2, a specific ligand of LRP1, exhibited high LRP1 binding efficiency. Additionally, TAT could penetrate through cell membranes without selectivity via an unsaturated pathway. To avoid the receptor saturation of Angiopep-2, TAT was also conjugated on the surface of liposomes, providing that the liposomes not only have effective BBB penetrating effect, but also have the glioma targeting function. The prepared DOX liposomes appeared good stability and narrow dispersity in serum with a diameter of 90 nm, and exhibited sustained DOX release behaviors. The conjunctions of Angiopep-2 and TAT were confirmed by 1 H NMR spectra. The BBB model, cellular uptake observations, antiproliferation study, and the cell ultrastructure analyses suggested that DOX-TAT-Ang-LIP could not only penetrate through BBB via transcytosis, but also concentrate in glioma, then enter into glioma cells and finally result in the necrosis of glioma cells.

Andrographolide-loaded nanoparticles for brain delivery: Formulation, characterisation and in vitro permeability using hCMEC/D3 cell line.

PubMed

Guccione, Clizia; Oufir, Mouhssin; Piazzini, Vieri; Eigenmann, Daniela Elisabeth; Jähne, Evelyn Andrea; Zabela, Volha; Faleschini, Maria Teresa; Bergonzi, Maria Camilla; Smiesko, Martin; Hamburger, Matthias; Bilia, Anna Rita

2017-10-01

Andrographolide (AG) is a major diterpenoid of the Asian medicinal plant Andrographis paniculata which has shown exciting pharmacological potential for the treatment of inflammation-related pathologies including neurodegenerative disorders. Conversely, the low bioavailability of AG still represents a limiting factor for its use. To overcome these limitations, AG was loaded into human serum albumin based nanoparticles (HSA NPs) and poly ethylcyanoacrylate nanoparticles (PECA NPs). HSA NPs were prepared by thermal (HSAT AG NPs) and chemical cross-linking (HSAC AG NPs), while PECA AG NPs were produced by emulsion-polymerization. NPs were characterized in terms of size, zeta (ζ)-potential, polydispersity, and release studies of AG. In addition, the ability of free AG and AG-loaded in PECA and HSAT NPs to cross the blood-brain barrier (BBB) was assessed using an in vitro BBB model based on human cerebral microvascular endothelial cell line (hCMEC/D3). For BBB drug permeability assays, a quantitative UPLC-MS/MS method for AG in Ringer HEPES buffer was developed and validated according to international regulatory guidelines for industry. Free AG did not permeate the BBB model, as also predicted by in silico studies. HSAT NPs improved by two-fold the permeation of AG while maintaining the integrity of the cell layer, while PECA NPs temporarily disrupted BBB integrity. Copyright © 2017 Elsevier B.V. All rights reserved.

Lipid Nanoparticles: A novel approach for brain targeting.

PubMed

Shankar, Ravi; Joshi, Monika; Pathak, Kamla

2018-06-10

Brain is a delicate organ, separated from general circulation and is characterized by the presence of relatively impermeable Blood Brain Barrier (BBB). The BBB maintains homeostasis in the brain thus restricting the entrance of foreign bodies and several molecules from reaching the brain. As a result several promising molecules do not reach the target site and fail to produce in vivo response. Nevertheless, lipid nanoparticles are taken up readily by the brain because of their lipophilic nature. The bioacceptable and biodegradable nature of lipid nanoparticles makes them less toxic and suited for brain targeting. In the present review the BBB, mechanism of transport across the BBB, strategies to bypass the blood-brain barrier have been presented. The aptness of lipid nanoparticles for brain targeting has been highlighted. The proposed mechanism of uptake of the lipid nanoparticles, methods of prolonging the plasma retention and various methods of preparation for formulation of effective delivery systems for brain targeting have been included and dealt in this review. Lipid based formulations can be designated as the current and future generation of drug delivery systems as these possess tremendous potential to bypass BBB and reach the target site due to their small size and ability to dodge the reticular endothelial system. However, these nanostructures need to be investigated intensively to successfully reach the clinical trials stage. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

[Antibiotic diffusion to central nervous system].

PubMed

Cabrera-Maqueda, J M; Fuentes Rumí, L; Valero López, G; Baidez Guerrero, A E; García Molina, E; Díaz Pérez, J; García-Vázquez, E

2018-02-01

Central nervous system (CNS) infections caused by pathogens with a reduced sensitivity to drugs are a therapeutic challenge. Transport of fluid and solutes is tightly controlled within CNS, where vasculature exhibits a blood-brain barrier (BBB).The entry of drugs, including antibiotics, into the cerebro-spinal fluid (CSF) is governed by molecular size, lipophilicity, plasma protein binding and their affinity to transport systems at the BBB. The ratio of the AUCCSF (Area under the curve in CSF)/AUCS (Area under the curve in serum) is the most accurate parameter to characterize drug penetration into the CSF. Linezolid, some fluoroquinolones and metronidazole get high CSF concentrations and are useful for treating susceptible pathogens. Some highly active antibiotic compounds with low BBB permeability can be directly administered into the ventricles together with concomitant intravenous therapy. The ideal antibiotic to treat CNS infections should be that with a small moderately lipophilic molecule, low plasma protein binding and low affinity to efflux pumps at BBB. Knowledge of the pharmacokinetics and pharmacodynamics of antibiotics at the BBB will assist to optimize antibiotic treatment in CNS infections. This article reviews the physicochemical properties of the main groups of antibiotics to assess which compounds are most promising for the treatment of CNS infections and how to use them in the daily clinical practice. © The Author 2018. Published by Sociedad Española de Quimioterapia.

Commercial Carpentry: Instructional Units. INST-BBB08691;BBB12485

ERIC Educational Resources Information Center

Diehl, Donald W.; Penner, Wayman R.

The guide contains 11 sections, each consisting of one or more units of instruction in commercial carpentry. The sections cover the following: introduction (orientation, safety, and applying for a job), leadership, related information (lumber, measuring, and fasteners), power and hand tools, blueprint reading, site preparation and layout, forming,…

Immobilized Artificial Membrane HPLC Derived Parameters vs PAMPA-BBB Data in Estimating in Situ Measured Blood-Brain Barrier Permeation of Drugs.

PubMed

Grumetto, Lucia; Russo, Giacomo; Barbato, Francesco

2016-08-01

The affinity indexes for phospholipids (log kW(IAM)) for 42 compounds were measured by high performance liquid chromatography (HPLC) on two different phospholipid-based stationary phases (immobilized artificial membrane, IAM), i.e., IAM.PC.MG and IAM.PC.DD2. The polar/electrostatic interaction forces between analytes and membrane phospholipids (Δlog kW(IAM)) were calculated as the differences between the experimental values of log kW(IAM) and those expected for isolipophilic neutral compounds having polar surface area (PSA) = 0. The values of passage through a porcine brain lipid extract (PBLE) artificial membrane for 36 out of the 42 compounds considered, measured by the so-called PAMPA-BBB technique, were taken from the literature (P0(PAMPA-BBB)). The values of blood-brain barrier (BBB) passage measured in situ, P0(in situ), for 38 out of the 42 compounds considered, taken from the literature, represented the permeability of the neutral forms on "efflux minimized" rodent models. The present work was aimed at verifying the soundness of Δlog kW(IAM) at describing the potential of passage through the BBB as compared to data achieved by the PAMPA-BBB technique. In a first instance, the values of log P0(PAMPA-BBB) (32 data points) were found significantly related to the n-octanol lipophilicity values of the neutral forms (log P(N)) (r(2) = 0.782) whereas no significant relationship (r(2) = 0.246) was found with lipophilicity values of the mixtures of ionized and neutral forms existing at the experimental pH 7.4 (log D(7.4)) as well as with either log kW(IAM) or Δlog kW(IAM) values. log P0(PAMPA-BBB) related moderately to log P0(in situ) values (r(2) = 0.604). The latter did not relate with either n-octanol lipophilicity indexes (log P(N) and log D(7.4)) or phospholipid affinity indexes (log kW(IAM)). In contrast, significant inverse linear relationships were observed between log P0(in situ) (38 data points) and Δlog kW(IAM) values for all the compounds but ibuprofen and chlorpromazine, which behaved as moderate outliers (r(2) = 0.656 and r(2) = 0.757 for values achieved on IAM.PC.MG and IAM.PC.DD2, respectively). Since log P0(in situ) refer to the "intrinsic permeability" of the analytes regardless their ionization degree, no correction for ionization of Δlog kW(IAM) values was needed. Furthermore, log P0(in situ) were found roughly linearly related to log BB values (i.e., the logarithm of the ratio brain concentration/blood concentration measured in vivo) for all the analytes but those predominantly present at the experimental pH 7.4 as anions. These results suggest that, at least for the data set considered, Δlog kW(IAM) parameters are more effective than log P0(PAMPA-BBB) at predicting log P0(in situ) values for all the analytes. Furthermore, ionization appears to affect differently, and much more markedly, BBB passage of acids (yielding anions) than that of the other ionizable compounds.

Nanoparticle transport across the blood brain barrier

PubMed Central

Grabrucker, Andreas M; Ruozi, Barbara; Belletti, Daniela; Pederzoli, Francesca; Forni, Flavio; Vandelli, Maria Angela; Tosi, Giovanni

2016-01-01

ABSTRACT While the role of the blood-brain barrier (BBB) is increasingly recognized in the (development of treatments targeting neurodegenerative disorders, to date, few strategies exist that enable drug delivery of non-BBB crossing molecules directly to their site of action, the brain. However, the recent advent of Nanomedicines may provide a potent tool to implement CNS targeted delivery of active compounds. Approaches for BBB crossing are deeply investigated in relation to the pathology: among the main important diseases of the CNS, this review focuses on the application of nanomedicines to neurodegenerative disorders (Alzheimer, Parkinson and Huntington's Disease) and to other brain pathologies as epilepsy, infectious diseases, multiple sclerosis, lysosomal storage disorders, strokes. PMID:27141426

How hormones influence composition and physiological function of the brain-blood barrier.

PubMed

Hampl, R; Bičíková, M; Sosvorová, L

2015-01-01

Hormones exert many actions in the brain. Their access and effects in the brain are regulated by the blood-brain barrier (BBB). Hormones as other substances may enter the brain and vice versa either by paracellular way requiring breaching tight junctions stitching the endothelial cells composing the BBB, or by passage through the cells (transcellular way). Hormones influence both ways through their receptors, both membrane and intracellular, present on/in the BBB. In the review the main examples are outlined how hormones influence the expression and function of proteins forming the tight junctions, as well as how they regulate expression and function of major protein transporters mediating transport of various substances including hormone themselves.

Oxygen therapy reduces secondary hemorrhage after thrombolysis in thromboembolic cerebral ischemia.

PubMed

Sun, Li; Zhou, Wei; Mueller, Christian; Sommer, Clemens; Heiland, Sabine; Bauer, Alexander T; Marti, Hugo H; Veltkamp, Roland

2010-09-01

Hyperbaric oxygen (HBO) and normobaric hyperoxia (NBO) protect the brain parenchyma and the cerebral microcirculation against ischemia. We studied their effect on secondary hemorrhage after thrombolysis in two thromboembolic middle cerebral artery occlusion (MCAO) (tMCAO) models. Beginning 60 minutes after tMCAO with either thrombin-induced thromboemboli (TT) or calcium-induced thromboemboli (CT), spontaneously hypertensive rats (n=96) breathed either air, 100% O(2) (NBO), or 100% O(2) at 3 bar (HBO) for 1 hour. Immediately thereafter, recombinant tissue plasminogen activator (rt-PA, 9 mg/kg) was injected. Although significant reperfusion was observed after thrombolysis in TT-tMCAO, vascular occlusion persisted in CT-tMCAO. In TT-tMCAO, NBO and HBO significantly reduced diffusion-weighted imaging-magnetic resonance imaging (MRI) lesion volume and postischemic blood-brain barrier (BBB) permeability on postcontrast T1-weighted images. NBO and, significantly more potently, HBO reduced macroscopic hemorrhage on T2* MRI and on corresponding postmortem cryosections. Oxygen therapy lowered hemoglobin content and attenuated activation of matrix metalloproteinases in the ischemic hemisphere. In contrast, NBO and HBO failed to reduce infarct size in CT but both decreased BBB damage and microscopic hemorrhagic transformation. Only HBO reduced hemoglobin extravasation in the ischemic hemisphere. In conclusion, NBO and HBO decrease infarct size after thromboembolic ischemia only if recanalization is successful. As NBO and HBO also reduce postthrombolytic intracerebral hemorrhage, combining the two with thrombolysis seems promising.

Protective effects of angiopoietin-like 4 on the blood-brain barrier in acute ischemic stroke treated with thrombolysis in mice.

PubMed

Zhang, Bin; Xu, Xiaofeng; Chu, Xiuli; Yu, Xiaoyang; Zhao, Yuwu

2017-04-03

Given the risk of blood-brain barrier damage (BBB) caused by ischemic and tissue plasminogen activator thrombolysis, the preservation of vascular integrity is important. Angiopoietin-like 4 (ANGPTL4), a protein secreted in hypoxia, is involved in the regulation of vascular permeability. We hypothesized that Angptl4 might exert a protective effect in thrombolysis through stabilizing blood-brain barrier and inhibit hyper-permeability. We investigated the role of Angptl4 in stroke using a transient focal cerebral ischemia mouse model. The treated mice were administered Angptl4 1h after the ischemic event upon reperfusion. Our results showed that Angptl4 combined with thrombolysis greatly reduced the infarct volume and consequent neurological deficit. Western blot analyses and gelatin zymography revealed that Angptl4 protected the integrity of the endothelium damaged by thrombolysis. Angptl4 inhibited the up-regulation of vascular endothelial growth factor (VEGF) in the vascular endothelium after stroke, which was suppressed by counteracting VEGFR signaling and diminishing downstream Src signaling, and led to the increased stability of junctions and improved endothelial cell barrier integrity. These findings demonstrated that Angptl4 protects the permeability of the BBB damaged by ischemic and thrombolysis. Suggested that Angptl4 might be a promising target molecule in therapies for vasoprotection after thrombolysis treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimal acquisition and modeling parameters for accurate assessment of low Ktrans blood-brain barrier permeability using dynamic contrast-enhanced MRI.

PubMed

Barnes, Samuel R; Ng, Thomas S C; Montagne, Axel; Law, Meng; Zlokovic, Berislav V; Jacobs, Russell E

2016-05-01

To determine optimal parameters for acquisition and processing of dynamic contrast-enhanced MRI (DCE-MRI) to detect small changes in near normal low blood-brain barrier (BBB) permeability. Using a contrast-to-noise ratio metric (K-CNR) for Ktrans precision and accuracy, the effects of kinetic model selection, scan duration, temporal resolution, signal drift, and length of baseline on the estimation of low permeability values was evaluated with simulations. The Patlak model was shown to give the highest K-CNR at low Ktrans . The Ktrans transition point, above which other models yielded superior results, was highly dependent on scan duration and tissue extravascular extracellular volume fraction (ve ). The highest K-CNR for low Ktrans was obtained when Patlak model analysis was combined with long scan times (10-30 min), modest temporal resolution (<60 s/image), and long baseline scans (1-4 min). Signal drift as low as 3% was shown to affect the accuracy of Ktrans estimation with Patlak analysis. DCE acquisition and modeling parameters are interdependent and should be optimized together for the tissue being imaged. Appropriately optimized protocols can detect even the subtlest changes in BBB integrity and may be used to probe the earliest changes in neurodegenerative diseases such as Alzheimer's disease and multiple sclerosis. © 2015 Wiley Periodicals, Inc.

Build back better principles for economic recovery: case study of the Victorian bushfires.

PubMed

Mannakkara, Sandeeka; Wilkinson, Suzanne

This paper looks at developing build back better (BBB) principles for economic recovery using the 2009 Victorian bushfires in Australia as a case study. The concept behind BBB-based economic recovery is to rejuvenate the economy in disaster-affected communities along with rebuilding to create resilient sustainable communities. A review of the literature identified several principles that can be applied to economic recovery to build back better. Data were collected in 2010 and 2011 by conducting semi- structured interviews with stakeholders who were directly involved in the Victorian bushfires recovery efforts, along with reports and other documentation. The recovery in Victoria displayed the use of BBB-based initiatives for economic recovery. The successes and shortcomings contributed to the creation of a modified list of BBB principles for economic recovery, including: creating an economic strategy based on thorough data collection; providing effective funding through grants and flexible low-interest loans; establishing business advice and mentoring services; providing incentives for businesses; assisting speedy rebuilding of business buildings; providing subsidised employee training and up-skilling programmes; and promoting local businesses through advertising.

Brain metastatic cancer cells release microRNA-181c-containing extracellular vesicles capable of destructing blood–brain barrier

PubMed Central

Tominaga, Naoomi; Kosaka, Nobuyoshi; Ono, Makiko; Katsuda, Takeshi; Yoshioka, Yusuke; Tamura, Kenji; Lötvall, Jan; Nakagama, Hitoshi; Ochiya, Takahiro

2015-01-01

Brain metastasis is an important cause of mortality in breast cancer patients. A key event during brain metastasis is the migration of cancer cells through blood–brain barrier (BBB). However, the molecular mechanism behind the passage through this natural barrier remains unclear. Here we show that cancer-derived extracellular vesicles (EVs), mediators of cell–cell communication via delivery of proteins and microRNAs (miRNAs), trigger the breakdown of BBB. Importantly, miR-181c promotes the destruction of BBB through the abnormal localization of actin via the downregulation of its target gene, PDPK1. PDPK1 degradation by miR-181c leads to the downregulation of phosphorylated cofilin and the resultant activated cofilin-induced modulation of actin dynamics. Furthermore, we demonstrate that systemic injection of brain metastatic cancer cell-derived EVs promoted brain metastasis of breast cancer cell lines and are preferentially incorporated into the brain in vivo. Taken together, these results indicate a novel mechanism of brain metastasis mediated by EVs that triggers the destruction of BBB. PMID:25828099

A dynamic in vivo-like organotypic blood-brain barrier model to probe metastatic brain tumors

NASA Astrophysics Data System (ADS)

Xu, Hui; Li, Zhongyu; Yu, Yue; Sizdahkhani, Saman; Ho, Winson S.; Yin, Fangchao; Wang, Li; Zhu, Guoli; Zhang, Min; Jiang, Lei; Zhuang, Zhengping; Qin, Jianhua

2016-11-01

The blood-brain barrier (BBB) restricts the uptake of many neuro-therapeutic molecules, presenting a formidable hurdle to drug development in brain diseases. We proposed a new and dynamic in vivo-like three-dimensional microfluidic system that replicates the key structural, functional and mechanical properties of the blood-brain barrier in vivo. Multiple factors in this system work synergistically to accentuate BBB-specific attributes-permitting the analysis of complex organ-level responses in both normal and pathological microenvironments in brain tumors. The complex BBB microenvironment is reproduced in this system via physical cell-cell interaction, vascular mechanical cues and cell migration. This model possesses the unique capability to examine brain metastasis of human lung, breast and melanoma cells and their therapeutic responses to chemotherapy. The results suggest that the interactions between cancer cells and astrocytes in BBB microenvironment might affect the ability of malignant brain tumors to traverse between brain and vascular compartments. Furthermore, quantification of spatially resolved barrier functions exists within a single assay, providing a versatile and valuable platform for pharmaceutical development, drug testing and neuroscientific research.

Blood-brain barrier transport of the alpha-keto acid analogs of amino acids.

PubMed

Steele, R D

1986-06-01

A number of alpha-keto acid analogs of amino acids have been found to penetrate the blood-brain barrier (BBB). Pyruvate, alpha-ketobutyrate, alpha-ketoisocaproate, and alpha-keto-gamma-methiolbutyrate all cross the BBB by a carrier-mediated process and by simple diffusion. Under normal physiological conditions, diffusion accounts for roughly 15% or less of total transport. Aromatic alpha-keto acids, phenylpyruvate, and p-hydroxyphenylpyruvate do not penetrate the BBB, nor do they inhibit the transport of other alpha-keto acids. Evidence based primarily on inhibition studies indicates that the carrier-mediated transport of alpha-keto acids occurs via the same carrier demonstrated previously for propionate, acetoacetate, and beta-hydroxybutyrate transport, commonly referred to as the monocarboxylate carrier. As a group, the alpha-keto acid analogs of the amino acids have the highest affinity for the carrier, followed by propionate and beta-hydroxybutyrate. Starvation for 4 days induces transport of alpha-keto acids, but transport is suppressed in rats fed commercial laboratory rations and subjected to portacaval shunts. The mitochondrial pyruvate translocator inhibitor alpha-cyanocinnamate has no effect on the BBB transport of alpha-keto acids.

Microbiome-host systems interactions: protective effects of propionate upon the blood-brain barrier.

PubMed

Hoyles, Lesley; Snelling, Tom; Umlai, Umm-Kulthum; Nicholson, Jeremy K; Carding, Simon R; Glen, Robert C; McArthur, Simon

2018-03-21

Gut microbiota composition and function are symbiotically linked with host health and altered in metabolic, inflammatory and neurodegenerative disorders. Three recognised mechanisms exist by which the microbiome influences the gut-brain axis: modification of autonomic/sensorimotor connections, immune activation, and neuroendocrine pathway regulation. We hypothesised interactions between circulating gut-derived microbial metabolites, and the blood-brain barrier (BBB) also contribute to the gut-brain axis. Propionate, produced from dietary substrates by colonic bacteria, stimulates intestinal gluconeogenesis and is associated with reduced stress behaviours, but its potential endocrine role has not been addressed. After demonstrating expression of the propionate receptor FFAR3 on human brain endothelium, we examined the impact of a physiologically relevant propionate concentration (1 μM) on BBB properties in vitro. Propionate inhibited pathways associated with non-specific microbial infections via a CD14-dependent mechanism, suppressed expression of LRP-1 and protected the BBB from oxidative stress via NRF2 (NFE2L2) signalling. Together, these results suggest gut-derived microbial metabolites interact with the BBB, representing a fourth facet of the gut-brain axis that warrants further attention.

Small endogenous molecules as moiety to improve targeting of CNS drugs.

PubMed

Sutera, Flavia Maria; De Caro, Viviana; Giannola, Libero Italo

2017-01-01

A major challenge in the development of novel neuro-therapeutic agents is to effectively overcome the blood-brain barrier (BBB), which acts as a 'working dynamic barrier'. The core problem in the treatment of neurodegenerative diseases is failed delivery of potential medicines due to their inadequate permeation rate. Areas covered: The present review gives a summary of endogenous moieties used in synthesizing prodrugs, derivatives and bioisosteric drugs appositely designed to structurally resemble physiological molecular entities able to be passively absorbed or carried by specific carrier proteins expressed at BBB level. In particular, this overview focuses on aminoacidic, glycosyl, purinergic, ureic and acidic fragments derivatives, most of which can take advantage from BBB carrier-mediated transporters, where passive diffusion is not permitted. Expert opinion: In the authors' perspective, further progress in this field could expedite successful translation of new chemical entities into clinical trials. Careful rationalization of the linkage between endogenous molecular structures and putative transporters binding sites could allow to useful work-flows and libraries for synthesizing new BBB-crossing therapeutic substances and/or multifunctional drugs for treatments of central disorders.

Α-aryl-N-alkyl nitrones, as potential agents for stroke treatment: synthesis, theoretical calculations, antioxidant, anti-inflammatory, neuroprotective, and brain-blood barrier permeability properties.

PubMed

Chioua, Mourad; Sucunza, David; Soriano, Elena; Hadjipavlou-Litina, Dimitra; Alcázar, Alberto; Ayuso, Irene; Oset-Gasque, María Jesús; González, María Pilar; Monjas, Leticia; Rodríguez-Franco, María Isabel; Marco-Contelles, José; Samadi, Abdelouahid

2012-01-12

We report the synthesis, theoretical calculations, the antioxidant, anti-inflammatory, and neuroprotective properties, and the ability to cross the blood-brain barrier (BBB) of (Z)-α-aryl and heteroaryl-N-alkyl nitrones as potential agents for stroke treatment. The majority of nitrones compete with DMSO for hydroxyl radicals, and most of them are potent lipoxygenase inhibitors. Cell viability-related (MTT assay) studies clearly showed that nitrones 1-3 and 10 give rise to significant neuroprotection. When compounds 1-11 were tested for necrotic cell death (LDH release test) nitrones 1-3, 6, 7, and 9 proved to be neuroprotective agents. In vitro evaluation of the BBB penetration of selected nitrones 1, 2, 10, and 11 using the PAMPA-BBB assay showed that all of them cross the BBB. Permeable quinoline nitrones 2 and 3 show potent combined antioxidant and neuroprotective properties and, therefore, can be considered as new lead compounds for further development in specific tests for potential stroke treatment.