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Sample records for alginate scaffold including

  1. Ionically cross-linked alginate hydrogels as tissue engineering scaffolds

    NASA Astrophysics Data System (ADS)

    Kuo, Catherine Kyleen

    Generation of living tissues through tissue engineering can be achieved via incorporation of cells into synthetic scaffolds designed to facilitate new tissue formation. Necessary characteristics of a scaffold include biocompatibility, high porosity with controllable pore size and interconnectivity, moldability, chemical and mechanical stability, and structural homogeneity. Hydrogels often possess many of the necessary characteristics and thus are favorable candidates for scaffolding. Alginate hydrogels are commonly made by ionically crosslinking with calcium ions from CaCl2 or CaSO4. These hydrogels are favored for their mild gel formation, however the gelation rate is rapid and uncontrollable (fast-gelation), resulting in varying crosslinking density throughout the gel. In this work, structurally homogeneous calcium alginate hydrogels were formed via a slow-gelation system that utilizes uniform mixing of CaCO3 with sodium alginate solution, and the addition of slowly hydrolyzing D-gluconic acid lactone to slowly release calcium ions for crosslinking. Homogeneity and mechanical properties of these hydrogels were shown to be superior to those of fast-gelled hydrogels. Gelation rate was controlled through the incorporation of CaSO4, and by varying total calcium content, polymer concentration and gelation temperature. Control over mechanical properties and diffusivity was demonstrated in the homogeneous hydrogels by adjusting compositional variables. Consistent control over solute diffusivity through gel discs reflected the structural homogeneity of the gels. To overcome the instability of ionically crosslinked gels in tissue culture medium, a method was developed to control the hydrogel dimensions by adjusting the ionic concentration of the medium. Stability of the hydrogels in this controlled environment was characterized through swelling experiments and mechanical testing. To provide for scaffold degradation and thereby promote tissue growth, alginate lyase was

  2. Reinforcement of porous alginate scaffolds by incorporating electrospun fibres.

    PubMed

    Sakai, Shinji; Takagi, Yousuke; Yamada, Yusuke; Yamaguchi, Tetsu; Kawakami, Koei

    2008-09-01

    The mechanical properties of scaffolds play a vital role in transmitting input mechanical signals to the cells within them. We aimed to modify mechanical properties of porous scaffolds by incorporating electrospun fibres into their frameworks. Porous constructs containing electrospun silicate fibres were prepared from Na-alginate aqueous solutions suspending the silicate fibres with (ASF) or without amino groups (NASF) via an all-aqueous method based on a freeze-drying technique. The repulsion forces of constructs containing ASF towards compression increased as the fibre content increased. In contrast, constructs containing NASF showed no such increases in repulsion forces. Cells seeded onto constructs containing ASF exhibited suppressed growth, similar to cells seeded onto alginate scaffolds without fibres. In contrast, cells seeded onto scaffolds containing NASF showed about two-fold faster growth than cells seeded onto scaffolds containing ASF. The differences in the mechanical properties and cell growth profiles between the scaffolds containing ASF and NASF can be explained by the formation and non-formation of electrostatic bonds between the fibres and alginate, respectively. The results obtained in the present study demonstrate the feasibility of incorporating electrospun fibres for reinforcement of alginate scaffolds and enhancement of cell growth. PMID:18689918

  3. Hydroxyapatite-doped alginate beads as scaffolds for the osteoblastic differentiation of mesenchymal stem cells.

    PubMed

    Wang, Martha O; Bracaglia, Laura; Thompson, Joshua A; Fisher, John P

    2016-09-01

    This work investigates the role of an osteoblastic matrix component, hydroxyapatite (HA), in modular alginate scaffolds to support osteoblastic differentiation of human mesenchymal stem cells for the purpose of tissue engineered bone constructs. This system is first evaluated in a tubular perfusion bioreactor, which has been shown to improve osteoblastic differentiation over static culture conditions. HMSCs in alginate scaffolds that contain HA show increased osteoblastic gene expression compared to cells in pure alginate scaffolds, as well as significantly more matrix production and mineralization. The differentiated hMSCs and cell-laid matrix are ultimately evaluated in an in vivo site specific model. Implantation of these scaffolds with preformed matrix into the rat femoral condyle defects results in abundant bone growth and significant incorporation of the scaffold into the surrounding tissue. The developed mineralized matrix, induced in part by the HA component in the scaffold, could lead to increased tissue development in critically sized defects, and should be included in future implant strategies. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2325-2333, 2016. PMID:27129735

  4. Preparation of aminated chitosan/alginate scaffold containing halloysite nanotubes with improved cell attachment.

    PubMed

    Amir Afshar, Hamideh; Ghaee, Azadeh

    2016-10-20

    The chemical nature of biomaterials play important role in cell attachment, proliferation and migration in tissue engineering. Chitosan and alginate are biodegradable and biocompatible polymers used as scaffolds for various medical and clinical applications. Amine groups of chitosan scaffolds play an important role in cell attachment and water adsorption but also associate with alginate carboxyl groups via electrostatic interactions and hydrogen bonding, consequently the activity of amine groups in the scaffold decreases. In this study, chitosan/alginate/halloysite nanotube (HNTs) composite scaffolds were prepared using a freeze-drying method. Amine treatment on the scaffold occurred through chemical methods, which in turn caused the hydroxyl groups to be replaced with carboxyl groups in chitosan and alginate, after which a reaction between ethylenediamine, 1-ethyl-3,(3-dimethylaminopropyl) carbodiimide (EDC) and scaffold triggered the amine groups to connect to the carboxyl groups of chitosan and alginate. The chemical structure, morphology and mechanical properties of the composite scaffolds were investigated by FTIR, CHNS, SEM/EDS and compression tests. The electrostatic attraction and hydrogen bonding between chitosan, alginate and halloysite was confirmed by FTIR spectroscopy. Chitosan/alginate/halloysite scaffolds exhibit significant enhancement in compressive strength compared with chitosan/alginate scaffolds. CHNS and EDS perfectly illustrate that amine groups were effectively introduced in the aminated scaffold. The growth and cell attachment of L929 cells as well as the cytotoxicity of the scaffolds were investigated by SEM and Alamar Blue (AB). The results indicated that the aminated chitosan/alginate/halloysite scaffold has better cell growth and cell adherence in comparison to that of chitosan/alginate/halloysite samples. Aminated chitosan/alginate/halloysite composite scaffolds exhibit great potential for applications in tissue engineering, ideally in

  5. Chitosan and alginate scaffolds for bone tissue regeneration.

    PubMed

    Olmez, S S; Korkusuz, P; Bilgili, H; Senel, S

    2007-06-01

    Polymeric scaffold for tissue regeneration was developed for veterinary applications. Oxytetracycline hydrochloride (OTC), which is a widely used antibiotic in veterinary medicine was chosen as the model compound. Gel formulations using chitosan and alginate were prepared in distilled water or in 1% (v/v) acetic acid solution. Sponges were also prepared by a freeze-drying process. Tripolyphosphate was used for cross-linking. Viscosity was decreased in the presence of OTC in chitosan gels whereas no difference was found with alginate gels. All gels showed pseudoplastic behaviour. Water absorption capacity was highest with chitosan/alginate sponges. The solvent used for preparation of the chitosan gels was found to affect the release of OTC. The release of OTC from the sponges was increased by cross-linking. Chitosan/alginate sponges showed the slowest and lowest drug release among the developed sponge formulations in this study. The formulations were found to be biocompatible, inducing no adverse reaction in vivo on surgically formed bone defects of radius of rabbits. The level of organization of the remodelled new bone in the treatment groups was better than that of control. Incorporation of OTC into formulations did not show any considerable enhancing effect. PMID:17663189

  6. Use an alginate scaffold-bone marrow stromal cell (BMSC) complex for the treatment of acute liver failure in rats.

    PubMed

    Lin, Jizong; Meng, Lili; Yao, Zhicheng; Chen, Shuxian; Yang, Jun; Tang, Zhaofeng; Lin, Nan; Xu, Ruiyun

    2015-01-01

    To evaluate the effects of alginate scaffold-bone marrow stromal cell (BMSC) in the treatment of acute liver failure in rats and provide a basis for in vivo application of artificial liver tissue. CM-DiI-labeled BMSCs were planted and grown on alginate scaffolds to form alginate scaffold-BMSC complex. Alginate scaffold-BMSC complex (the experimental group) or alginate scaffolds (the control group) were placed onto the surface of liver wound of rats after 70% of hepatectomy. The scaffold-BMSC complex and alginate scaffolds were removed after 4 weeks and fluorescence microscopy was used to track the growth and distribution of CM-DiI-labeled BMSCs. The liver tissues were stained for albumin and glycogen to investigate the differentiation of BMSCs on alginate scaffolds. The survival rate and liver function were also compared between the two groups of rats. BMSCs on alginate scaffolds and liver tissues were clearly demonstrated by CM-DiI labeling. BMSCs on alginate scaffolds secreted albumin and produced glycogen. The survival rate and liver function of the rats of the experimental group were significantly higher than that the control group rats. Alginate scaffold-BMSC complex promotes the regeneration of liver tissues in rats of acute liver failure. PMID:26550170

  7. Optimization of keratin/alginate scaffold using RSM and its characterization for tissue engineering.

    PubMed

    Gupta, Pratima; Nayak, Kush Kumar

    2016-04-01

    The scaffold for tissue engineering was fabricated from a binary blend of keratin/alginate. The concentration and ratio of keratin and alginate was optimized by response surface methodology in a scaffold. The structural compatibility between keratin and alginate was examined by X-ray diffractometer and Fourier transforms infrared spectroscopy. Apparent porosity of the scaffold was calculated by Archimedes principles and its observed value of was found 96.25 ± 0.04%. The pore size of the scaffold was observed in the range between 10 and 200 μm. Tensile strength (0.33 ± 0.26 MPa) and percent of elongation at break (23.33 ± 2.52%) are the reported mechanical strength of the scaffold. Positive antimicrobial activity and in vitro degradation further confirms the fabrication of a scaffold required for tissue engineering application. PMID:26691383

  8. Fabrication of photo-crosslinked chitosan- gelatin scaffold in sodium alginate hydrogel for chondrocyte culture.

    PubMed

    Zhao, Peng; Deng, Cuijun; Xu, Hongzhen; Tang, Xing; He, Hailong; Lin, Chao; Su, Jiansheng

    2014-01-01

    Photo-crosslinked chitosan-gelatin scaffolds were fabricated and applied for chondrocyte culture in vitro. Photocurable methacryloyl chitosan was synthesized and characterized by FTIR and 1H NMR, respectively. Microstructure and mechanical properties of the chitosan-gelatin scaffold treated with or without EDC as crosslinking agent were analyzed by scanning electronic microscopy (SEM), compression and viscoelastic measurement. It is demonstrated that EDC-treated chitosan-gelatin scaffold possesses better porous structure and improved mechanical properties. Photo-crosslinked chitosan-gelatin scaffold could be further integrated in sodium alginate hydrogel using calcium chloride to support proliferation of chondrocytes for over 21 days and maintain spherical phenotype, as evaluated by AlamarBlue assay and SEM, respectively, implying that the chitosan-gelatin-hydrogel system exhibits great cyto-biocompatibility. Results of this study show that photo-crosslinked chitosan-gelatin scaffold in sodium alginate hydrogel is suited as a scaffold candidate for cartilage tissue engineering. PMID:24211948

  9. An additive manufacturing-based PCL-alginate-chondrocyte bioprinted scaffold for cartilage tissue engineering.

    PubMed

    Kundu, Joydip; Shim, Jin-Hyung; Jang, Jinah; Kim, Sung-Won; Cho, Dong-Woo

    2015-11-01

    Regenerative medicine is targeted to improve, restore or replace damaged tissues or organs using a combination of cells, materials and growth factors. Both tissue engineering and developmental biology currently deal with the process of tissue self-assembly and extracellular matrix (ECM) deposition. In this investigation, additive manufacturing (AM) with a multihead deposition system (MHDS) was used to fabricate three-dimensional (3D) cell-printed scaffolds using layer-by-layer (LBL) deposition of polycaprolactone (PCL) and chondrocyte cell-encapsulated alginate hydrogel. Appropriate cell dispensing conditions and optimum alginate concentrations for maintaining cell viability were determined. In vitro cell-based biochemical assays were performed to determine glycosaminoglycans (GAGs), DNA and total collagen contents from different PCL-alginate gel constructs. PCL-alginate gels containing transforming growth factor-β (TGFβ) showed higher ECM formation. The 3D cell-printed scaffolds of PCL-alginate gel were implanted in the dorsal subcutaneous spaces of female nude mice. Histochemical [Alcian blue and haematoxylin and eosin (H&E) staining] and immunohistochemical (type II collagen) analyses of the retrieved implants after 4 weeks revealed enhanced cartilage tissue and type II collagen fibril formation in the PCL-alginate gel (+TGFβ) hybrid scaffold. In conclusion, we present an innovative cell-printed scaffold for cartilage regeneration fabricated by an advanced bioprinting technology. PMID:23349081

  10. Differentiation of Wharton's jelly mesenchymal stem cells into neurons in alginate scaffold

    PubMed Central

    Hosseini, Seyed Mojtaba; Vasaghi, Attiyeh; Nakhlparvar, Newsha; Roshanravan, Reza; Talaei-khozani, Tahereh; Razi, Zahra

    2015-01-01

    Alginate scaffold has been considered as an appropriate biomaterial for promoting the differentiation of embryonic stem cells toward neuronal cell lineage. We hypothesized that alginate scaffold is suitable for culturing Wharton's jelly mesenchymal stem cells (WJMSCs) and can promote the differentiation of WJMSCs into neuron-like cells. In this study, we cultured WJMSCs in a three-dimensional scaffold fabricated by 0.25% alginate and 50 mM CaCl2 in the presence of neurogenic medium containing 10 μM retinoic acid and 20 ng/mL basic fibroblast growth factor. These cells were also cultured in conventional two-dimensional culture condition in the presence of neurogenic medium as controls. After 10 days, immunofluorescence staining was performed for detecting β-tubulin (marker for WJMSCs-differentiated neuron) and CD271 (motor neuron marker). β-Tubulin and CD271 expression levels were significantly greater in the WJMSCs cultured in the three-dimensional alginate scaffold than in the conventional two-dimensional culture condition. These findings suggest that three-dimensional alginate scaffold cell culture system can induce neuronal differentiation of WJMSCs effectively. PMID:26487861

  11. Controlled nucleation of hydroxyapatite on alginate scaffolds for stem cell-based bone tissue engineering

    PubMed Central

    Suárez-González, Darilis; Barnhart, Kara; Saito, Eiji; Vanderby, Ray; Hollister, Scott; Murphy, William L.

    2010-01-01

    Current bone tissue engineering strategies aim to grow a tissue similar to native bone by combining cells and biologically active molecules with a scaffold material. In this study, a macroporous scaffold made from the seaweed-derived polymer alginate was synthesized and mineralized for cell-based bone tissue engineering applications. Nucleation of a bone-like hydroxyapatite mineral was achieved by incubating the scaffold in modified simulated body fluids (mSBF) for four weeks. Analysis using scanning electron microscopy and energy dispersive x-ray analysis indicated growth of a continuous layer of mineral primarily composed of calcium and phosphorous. X-ray diffraction analysis showed peaks associated with hydroxyapatite, the major inorganic constituent of human bone tissue. In addition to the mineral characterization, the ability to control nucleation on the surface, into the bulk of the material, or on the inner pore surfaces of scaffolds was demonstrated. Finally, human MSCs attached and proliferated on the mineralized scaffolds and cell attachment improved when seeding cells on mineral coated alginate scaffolds. This novel alginate- HAP composite material could be used in bone tissue engineering as a scaffold material to deliver cells, and perhaps also biologically active molecules. PMID:20574984

  12. Interpenetrated Si-HPMC/alginate hydrogels as a potential scaffold for human tissue regeneration.

    PubMed

    Viguier, Alexia; Boyer, Cecile; Chassenieux, Christophe; Benyahia, Lazhar; Guicheux, Jérôme; Weiss, Pierre; Rethore, Gildas; Nicolai, Taco

    2016-05-01

    Interpenetrated gels of biocompatible polysaccharides alginate and silanized hydroxypropyl methyl cellulose (Si-HPMC) have been studied in order to assess their potential as scaffolds for the regeneration of human tissues. Si-HPMC networks were formed by reduction of the pH to neutral and alginate networks were formed by progressive in situ release of Ca(2+). Linear and non-linear mechanical properties of the mixed gels at different polymer and calcium concentrations were compared with those of the corresponding single gels. The alginate/Si-HPMC gels were found to be stiffer than pure Si-HPMC gels, but weaker and more deformable than pure alginate gels. No significant difference was found for the maximum stress at rupture measured during compression for all these gels. The degrees of swelling or contraction in excess water at pH 7 as well as the release of Ca(2+) was measured as a function of time. Pure alginate gels contracted by as much as 50 % and showed syneresis, which was much reduced or even eliminated for mixed gels. The important release of Ca(2+) upon ageing for pure alginate gels was much reduced for the mixed gels. Furthermore, results of cytocompatibility assays indicated that there was no cytotoxicity of Si-HPMC/alginate hydrogels in 2D and 3D culture of human SW1353 cells. The results show that using interpenetrated Si-HPMC/alginate gels has clear advantages over the use of single gels for application in tissue regeneration. PMID:27022979

  13. Mechanically reinforced cell-laden scaffolds formed using alginate-based bioink printed onto the surface of a PCL/alginate mesh structure for regeneration of hard tissue.

    PubMed

    Kim, Yong Bok; Lee, Hyeongjin; Yang, Gi-Hoon; Choi, Chang Hyun; Lee, DaeWeon; Hwang, Heon; Jung, Won-Kyo; Yoon, Hyeon; Kim, Geun Hyung

    2016-01-01

    Cell-printing technology has provided a new paradigm for biofabrication, with potential to overcome several shortcomings of conventional scaffold-based tissue regeneration strategies via controlled delivery of various cell types in well-defined target regions. Here we describe a cell-printing method to obtain mechanically reinforced multi-layered cell-embedded scaffolds, formed of micron-scale poly(ε-caprolactone) (PCL)/alginate struts coated with alginate-based bioink. To compare the physical and cellular activities, we used a scaffold composed of pure alginate (without cells) coated PCL/alginate struts as a control. We systematically varied the ratio of alginate cross-linking agent, and determined the optimal cell-coating conditions to form the PCL/alginate struts. Following fabrication of the cell (MG63)-laden PCL/alginate scaffold, the bioactivity was evaluated in vitro. The laden cells exhibited a substantially more developed cytoskeleton compared with those on a control scaffold consisting of the same material composition. Based on these results, the printed cells exhibited a significantly more homogenous distribution within the scaffold compared with the control. Cell proliferation was determined via MTT assays at 1, 3, 7, and 14 days of culture, and the proliferation of the cell-printed scaffold was substantially in excess (∼2.4-fold) of that on the control. Furthermore, the osteogenic activity such as ALP was measured, and the cell-laden scaffold exhibited significantly greater activity (∼3.2-fold) compared with the control scaffold. PMID:26409783

  14. Fabrication, characterization, and biocompatibility of single-walled carbon nanotube-reinforced alginate composite scaffolds manufactured using freeform fabrication technique.

    PubMed

    Yildirim, Eda D; Yin, Xi; Nair, Kalyani; Sun, Wei

    2008-11-01

    Composite polymeric scaffolds from alginate and single-walled carbon nanotube (SWCNT) were produced using a freeform fabrication technique. The scaffolds were characterized for their structural, mechanical, and biological properties by scanning electron microscopy, Raman spectroscopy, tensile testing, and cell-scaffold interaction study. Three-dimensional hybrid alginate/SWCNT tissue scaffolds were fabricated in a multinozzle biopolymer deposition system, which makes possible to disperse and align SWCNTs in the alginate matrix. The structure of the resultant scaffolds was significantly altered due to SWCNT reinforcement, which was confirmed by Raman spectroscopy. Microtensile testing presented a reinforcement effect of SWCNT to the mechanical strength of the alginate struts. Ogden constitutive modeling was utilized to predict the stress-strain relationship of the alginate scaffold, which compared well with the experimental data. Cellular study by rat heart endothelial cell showed that the SWCNT incorporated in the alginate structure improved cell adhesion and proliferation. Our study suggests that hybrid alginate/SWCNT scaffolds are a promising biomaterial for tissue engineering applications. PMID:18506813

  15. Transplantation of Neural Stem Cells Cultured in Alginate Scaffold for Spinal Cord Injury in Rats

    PubMed Central

    Sharafkhah, Ali; Koohi-Hosseinabadi, Omid; Semsar-Kazerooni, Maryam

    2016-01-01

    Study Design This study investigated the effects of transplantation of alginate encapsulated neural stem cells (NSCs) on spinal cord injury in Sprague-Dawley male rats. The neurological functions were assessed for 6 weeks after transplantation along with a histological study and measurement of caspase-3 levels. Purpose The aim of this study was to discover whether NSCs cultured in alginate transplantation improve recovery from spinal cord injury. Overview of Literature Spinal cord injury is one of the leading causes of disability and it has no effective treatment. Spinal cord injury can also cause sensory impairment. With an impetus on using stem cells therapy in various central nervous system settings, there is an interest in using stem cells for addressing spinal cord injury. Neural stem cell is one type of stem cells that is able to differentiate to all three neural lineages and it shows promise in spinal injury treatment. Furthermore, a number of studies have shown that culturing NSCs in three-dimensional (3D) scaffolds like alginate could enhance neural differentiation. Methods The NSCs were isolated from 14-day-old rat embryos. The isolated NSCs were cultured in growth media containing basic fibroblast growth factor and endothelial growth factor. The cells were characterized by differentiating to three neural lineages and they were cultured in an alginate scaffold. After 7 days the cells were encapsulated and transplanted in a rat model of spinal cord injury. Results Our data showed that culturing in an alginate 3D scaffold and transplantation of the NSCs could improve neurological outcome in a rat model of spinal cord injury. The inflammation scores and lesion sizes and also the activity of caspase-3 (for apoptosis evaluation) were less in encapsulated neural stem cell transplantation cases. Conclusions Transplantation of NSCs that were cultured in an alginate scaffold led to a better clinical and histological outcome for recovery from spinal cord injury in

  16. Copper-releasing, boron-containing bioactive glass-based scaffolds coated with alginate for bone tissue engineering.

    PubMed

    Erol, M M; Mouriňo, V; Newby, P; Chatzistavrou, X; Roether, J A; Hupa, L; Boccaccini, Aldo R

    2012-02-01

    The aim of this study was to synthesize and characterize new boron-containing bioactive glass-based scaffolds coated with alginate cross-linked with copper ions. A recently developed bioactive glass powder with nominal composition (wt.%) 65 SiO2, 15 CaO, 18.4 Na2O, 0.1 MgO and 1.5 B2O3 was fabricated as porous scaffolds by the foam replica method. Scaffolds were alginate coated by dipping them in alginate solution. Scanning electron microscopy investigations indicated that the alginate effectively attached on the surface of the three-dimensional scaffolds leading to a homogeneous coating. It was confirmed that the scaffold structure remained amorphous after the sintering process and that the alginate coating improved the scaffold bioactivity and mechanical properties. Copper release studies showed that the alginate-coated scaffolds allowed controlled release of copper ions. The novel copper-releasing composite scaffolds represent promising candidates for bone regeneration. PMID:22040685

  17. Fabrication and characterization of novel nano-biocomposite scaffold of chitosan-gelatin-alginate-hydroxyapatite for bone tissue engineering.

    PubMed

    Sharma, Chhavi; Dinda, Amit Kumar; Potdar, Pravin D; Chou, Chia-Fu; Mishra, Narayan Chandra

    2016-07-01

    A novel nano-biocomposite scaffold was fabricated in bead form by applying simple foaming method, using a combination of natural polymers-chitosan, gelatin, alginate and a bioceramic-nano-hydroxyapatite (nHAp). This approach of combining nHAp with natural polymers to fabricate the composite scaffold, can provide good mechanical strength and biological property mimicking natural bone. Environmental scanning electron microscopy (ESEM) images of the nano-biocomposite scaffold revealed the presence of interconnected pores, mostly spread over the whole surface of the scaffold. The nHAp particulates have covered the surface of the composite matrix and made the surface of the scaffold rougher. The scaffold has a porosity of 82% with a mean pore size of 112±19.0μm. Swelling and degradation studies of the scaffold showed that the scaffold possesses excellent properties of hydrophilicity and biodegradability. Short term mechanical testing of the scaffold does not reveal any rupturing after agitation under physiological conditions, which is an indicative of good mechanical stability of the scaffold. In vitro cell culture studies by seeding osteoblast cells over the composite scaffold showed good cell viability, proliferation rate, adhesion and maintenance of osteoblastic phenotype as indicated by MTT assay, ESEM of cell-scaffold construct, histological staining and gene expression studies, respectively. Thus, it could be stated that the nano-biocomposite scaffold of chitosan-gelatin-alginate-nHAp has the paramount importance for applications in bone tissue-engineering in future regenerative therapies. PMID:27127072

  18. Composite ECM-alginate microfibers produced by microfluidics as scaffolds with biomineralization potential.

    PubMed

    Angelozzi, Marco; Miotto, Martina; Penolazzi, Letizia; Mazzitelli, Stefania; Keane, Timothy; Badylak, Stephen F; Piva, Roberta; Nastruzzi, Claudio

    2015-11-01

    A novel approach to produce artificial bone composites (microfibers) with distinctive features mimicking natural tissue was investigated. Currently proposed inorganic materials (e.g. apatite matrixes) lack self-assembly and thereby limit interactions between cells and the material. The present work investigates the feasibility of creating "bio-inspired materials" specifically designed to overcome certain limitations inherent to current biomaterials. We examined the dimensions, morphology, and constitutive features of a composite hydrogel which combined an alginate based microfiber with a gelatin solution or a particulate form of urinary bladder matrix (UBM). The effectiveness of the composite microfibers to induce and modulate osteoblastic differentiation in three-dimensional (3D) scaffolds without altering the viability and morphological characteristics of the cells was investigated. The present study describes a novel alginate microfiber production method with the use of microfluidics. The microfluidic procedure allowed for precise tuning of microfibers which resulted in enhanced viability and function of embedded cells. PMID:26249575

  19. Fish collagen/alginate/chitooligosaccharides integrated scaffold for skin tissue regeneration application.

    PubMed

    Chandika, Pathum; Ko, Seok-Chun; Oh, Gun-Woo; Heo, Seong-Yeong; Nguyen, Van-Tinh; Jeon, You-Jin; Lee, Bonggi; Jang, Chul Ho; Kim, GeunHyung; Park, Won Sun; Chang, Wonseok; Choi, Il-Whan; Jung, Won-Kyo

    2015-11-01

    An emerging paradigm in wound healing techniques is that a tissue-engineered skin substitute offers an alternative approach to create functional skin tissue. Here we developed a fish collagen/alginate (FCA) sponge scaffold that was functionalized by different molecular weights of chitooligosaccharides (COSs) with the use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as a cross-linking agent. The effects of cross-linking were analyzed by Fourier transform infrared spectroscopy. The results indicate that the homogeneous materials blending and cross-linking intensity were dependent on the molecular weights of COSs. The highly interconnected porous architecture with 160-260μm pore size and over 90% porosity and COS's MW driven swelling and retention capacity, tensile property and in vitro biodegradation behavior guaranteed the FCA/COS scaffolds for skin tissue engineering application. Further improvement of these properties enhanced the cytocompatibility of all the scaffolds, especially the scaffolds containing COSs with MW in the range of 1-3kDa (FCA/COS1) showed the best cytocompatibility. These physicochemical, mechanical, and biological properties suggest that the FCA/COS1 scaffold is a superior candidate that can be used for skin tissue regeneration. PMID:26306410

  20. Enhancing cell migration in shape-memory alginate-collagen composite scaffolds: In vitro and ex vivo assessment for intervertebral disc repair.

    PubMed

    Guillaume, Olivier; Naqvi, Syeda Masooma; Lennon, Kerri; Buckley, Conor Timothy

    2015-04-01

    Lower lumbar disc disorders pose a significant problem in an aging society with substantial socioeconomic consequences. Both inner tissue (nucleus pulposus) and outer tissue (annulus fibrosus) of the intervertebral disc are affected by such debilitating disorders and can lead to disc herniation and lower back pain. In this study, we developed an alginate-collagen composite porous scaffold with shape-memory properties to fill defects occurring in annulus fibrosus tissue of degenerated intervertebral discs, which has the potential to be administered using minimal invasive surgery. In the first part of this work, we assessed how collagen incorporation on preformed alginate scaffolds influences the physical properties of the final composite scaffold. We also evaluated the ability of annulus fibrosus cells to attach, migrate, and proliferate on the composite alginate-collagen scaffolds compared to control scaffolds (alginate only). In vitro experiments, performed in intervertebral disc-like microenvironmental conditions (low glucose and low oxygen concentrations), revealed that for alginate only scaffolds, annulus fibrosus cells agglomerated in clusters with limited infiltration and migration capacity. In comparison, for alginate-collagen scaffolds, annulus fibrosus cells readily attached and colonized constructs, while preserving their typical fibroblastic-like cell morphology with spreading behavior and intense cytoskeleton expression. In a second part of this study, we investigated the effects of alginate-collagen scaffold when seeded with bone marrow derived mesenchymal stem cells. In vitro, we observed that alginate-collagen porous scaffolds supported cell proliferation and extracellular matrix deposition (collagen type I), with secretion amplified by the local release of transforming growth factor-β3. In addition, when cultured in ex vivo organ defect model, alginate-collagen scaffolds maintained viability of transplanted mesenchymal stem cells for up to 5

  1. Design and Fabrication of a Biodegradable, Covalently Crosslinked Shape-Memory Alginate Scaffold for Cell and Growth Factor Delivery

    PubMed Central

    Wang, Lin; Shansky, Janet; Borselli, Cristina; Mooney, David

    2012-01-01

    The successful use of transplanted cells and/or growth factors for tissue repair is limited by a significant cell loss and/or rapid growth factor diffusion soon after implantation. Highly porous alginate scaffolds formed with covalent crosslinking have been used to improve cell survival and growth factor release kinetics, but require open-wound surgical procedures for insertion and have not previously been designed to readily degrade in vivo. In this study, a biodegradable, partially crosslinked alginate scaffold with shape-memory properties was fabricated for minimally invasive surgical applications. A mixture of high and low molecular weight partially oxidized alginate modified with RGD peptides was covalently crosslinked using carbodiimide chemistry. The scaffold was compressible 11-fold and returned to its original shape when rehydrated. Scaffold degradation properties in vitro indicated ∼85% mass loss by 28 days. The greater than 90% porous scaffolds released the recombinant growth factor insulin-like growth factor-1 over several days in vitro and allowed skeletal muscle cell survival, proliferation, and migration from the scaffold over a 28-day period. The compressible scaffold thus has the potential to be delivered by a minimally invasive technique, and when rehydrated in vivo with cells and/or growth factors, could serve as a temporary delivery vehicle for tissue repair. PMID:22646518

  2. Porous matrix of calcium alginate/gelatin with enhanced properties as scaffold for cell culture.

    PubMed

    Cuadros, Teresa R; Erices, Alejandro A; Aguilera, José M

    2015-06-01

    Hydrophilic polysaccharides can be used to prepare porous matrices with a range of possible applications. One such application involves acting as scaffolds for cell culture. A new homogeneous and highly porous biopolymeric porous matrix (BPM) of calcium alginate/gelatin was produced by following a simple process. The key to this process was the selection of the porogen (aerated gelatin). The preparation technique comprises the following steps: incorporating the porogen into the solution of alginate (3%), molding, cross-linking the alginate in 1.41% CaCl2 (maximum gel strength; Cuadros et al., 2012. Carbohydr. Polym. 89, 1198-1206), molding, leaching and lyophilization. Cylinders of BPM were shown to have a relative density of 0.0274 ± 0.002, porosity of 97.26 ± 0.18%, an average internal pore size of 204 ± 58 µm and enhanced mechanical properties, while imbibing more than 11 times their dry weight in water. In vitro cell culture testing within BPM using mesenchymal stem cells was demonstrated by MTT assays and expression of alkaline phosphatase. The BPM provided a suitable microenvironment for seeding, adhesion, proliferation and osteogenic differentiation of cells. The preparation technique and resulting porous matrix represent potential tools for future study and further applications. PMID:25661688

  3. Delivery of Alginate Scaffold Releasing Two Trophic Factors for Spinal Cord Injury Repair

    PubMed Central

    Grulova, I.; Slovinska, L.; Blaško, J.; Devaux, S.; Wisztorski, M.; Salzet, M.; Fournier, I.; Kryukov, O.; Cohen, S.; Cizkova, D.

    2015-01-01

    Spinal cord injury (SCI) has been implicated in neural cell loss and consequently functional motor and sensory impairment. In this study, we propose an alginate -based neurobridge enriched with/without trophic growth factors (GFs) that can be utilized as a therapeutic approach for spinal cord repair. The bioavailability of key GFs, such as Epidermal Growth factor (EGF) and basic Fibroblast Growth Factor (bFGF) released from injected alginate biomaterial to the central lesion site significantly enhanced the sparing of spinal cord tissue and increased the number of surviving neurons (choline acetyltransferase positive motoneurons) and sensory fibres. In addition, we document enhanced outgrowth of corticospinal tract axons and presence of blood vessels at the central lesion. Tissue proteomics was performed at 3, 7 and 10 days after SCI in rats indicated the presence of anti-inflammatory factors in segments above the central lesion site, whereas in segments below, neurite outgrowth factors, inflammatory cytokines and chondroitin sulfate proteoglycan of the lectican protein family were overexpressed. Collectively, based on our data, we confirm that functional recovery was significantly improved in SCI groups receiving alginate scaffold with affinity-bound growth factors (ALG +GFs), compared to SCI animals without biomaterial treatment. PMID:26348665

  4. A tunable silk-alginate hydrogel scaffold for stem cell culture and transplantation

    PubMed Central

    Ziv, Keren; Nuhn, Harald; Ben-Haim, Yael; Sasportas, Laura S.; Kempen, Paul J.; Niedringhaus, Thomas P.; Hrynyk, Michael; Sinclair, Robert; Barron, Annelise E.; Gambhir, Sanjiv S.

    2014-01-01

    One of the major challenges in regenerative medicine is the ability to recreate the stem cell niche, which is defined by its signaling molecules, the creation of cytokine gradients, and the modulation of matrix stiffness. A wide range of scaffolds has been developed in order to recapitulate the stem cell niche, among them hydrogels. This paper reports the development of a new silk-alginate based hydrogel with a focus on stem cell culture. This biocomposite allows to fine tune its elasticity during cell culture, addressing the importance of mechanotransduction during stem cell differentiation. The silk-alginate scaffold promotes adherence of mouse embryonic stem cells and cell survival upon transplantation. In addition, it has tunable stiffness as function of the silk-alginte ratio and the concentration of crosslinker - a characteristic that is very hard to accomplish in current hydrogels. The hydrogel and the presented results represents key steps on the way of creating artificial stem cell niche, opening up new paths in regenerative medicine. PMID:24484675

  5. Development and characterization of novel porous 3D alginate-cockle shell powder nanobiocomposite bone scaffold.

    PubMed

    Bharatham, B Hemabarathy; Abu Bakar, Md Zuki; Perimal, Enoch Kumar; Yusof, Loqman Mohamed; Hamid, Muhajir

    2014-01-01

    A novel porous three-dimensional bone scaffold was developed using a natural polymer (alginate/Alg) in combination with a naturally obtained biomineral (nano cockle shell powder/nCP) through lyophilization techniques. The scaffold was developed in varying composition mixture of Alg-nCP and characterized using various evaluation techniques as well as preliminary in vitro studies on MG63 human osteoblast cells. Morphological observations using SEM revealed variations in structures with the use of different Alg-nCP composition ratios. All the developed scaffolds showed a porous structure with pore sizes ideal for facilitating new bone growth; however, not all combination mixtures showed subsequent favorable characteristics to be used for biological applications. Scaffolds produced using the combination mixture of 40% Alg and 60% nCP produced significantly promising results in terms of mechanical strength, degradation rate, and increased cell proliferation rates making it potentially the optimum composition mixture of Alg-nCP with future application prospects. PMID:25110655

  6. Development and Characterization of Novel Porous 3D Alginate-Cockle Shell Powder Nanobiocomposite Bone Scaffold

    PubMed Central

    Bharatham, B. Hemabarathy; Abu Bakar, Md. Zuki; Perimal, Enoch Kumar; Yusof, Loqman Mohamed; Hamid, Muhajir

    2014-01-01

    A novel porous three-dimensional bone scaffold was developed using a natural polymer (alginate/Alg) in combination with a naturally obtained biomineral (nano cockle shell powder/nCP) through lyophilization techniques. The scaffold was developed in varying composition mixture of Alg-nCP and characterized using various evaluation techniques as well as preliminary in vitro studies on MG63 human osteoblast cells. Morphological observations using SEM revealed variations in structures with the use of different Alg-nCP composition ratios. All the developed scaffolds showed a porous structure with pore sizes ideal for facilitating new bone growth; however, not all combination mixtures showed subsequent favorable characteristics to be used for biological applications. Scaffolds produced using the combination mixture of 40% Alg and 60% nCP produced significantly promising results in terms of mechanical strength, degradation rate, and increased cell proliferation rates making it potentially the optimum composition mixture of Alg-nCP with future application prospects. PMID:25110655

  7. Three-dimensional plotted hydroxyapatite scaffolds with predefined architecture: comparison of stabilization by alginate cross-linking versus sintering.

    PubMed

    Kumar, Alok; Akkineni, Ashwini R; Basu, Bikramjit; Gelinsky, Michael

    2016-03-01

    Scaffolds for bone tissue engineering are essentially characterized by porous three-dimensional structures with interconnected pores to facilitate the exchange of nutrients and removal of waste products from cells, thereby promoting cell proliferation in such engineered scaffolds. Although hydroxyapatite is widely being considered for bone tissue engineering applications due to its occurrence in the natural extracellular matrix of this tissue, limited reports are available on additive manufacturing of hydroxyapatite-based materials. In this perspective, hydroxyapatite-based three-dimensional porous scaffolds with two different binders (maltodextrin and sodium alginate) were fabricated using the extrusion method of three-dimensional plotting and the results were compared in reference to the structural properties of scaffolds processed via chemical stabilization and sintering routes, respectively. With the optimal processing conditions regarding to pH and viscosity of binder-loaded hydroxyapatite pastes, scaffolds with parallelepiped porous architecture having up to 74% porosity were fabricated. Interestingly, sintering of the as-plotted hydroxyapatite-sodium alginate (cross-linked with CaCl2 solution) scaffolds led to the formation of chlorapatite (Ca9.54P5.98O23.8Cl1.60(OH)2.74). Both the sintered scaffolds displayed progressive deformation and delayed fracture under compressive loading, with hydroxyapatite-alginate scaffolds exhibiting a higher compressive strength (9.5 ± 0.5 MPa) than hydroxyapatite-maltodextrin scaffolds (7.0 ± 0.6 MPa). The difference in properties is explained in terms of the phase assemblage and microstructure. PMID:26589296

  8. Structural modification and characterization of bacterial cellulose-alginate composite scaffolds for tissue engineering.

    PubMed

    Kirdponpattara, Suchata; Khamkeaw, Arnon; Sanchavanakit, Neeracha; Pavasant, Prasit; Phisalaphong, Muenduen

    2015-11-01

    A novel bacterial cellulose-alginate composite scaffold (N-BCA) was fabricated by freeze drying and subsequent crosslinking with Ca(2+). The N-BCA then underwent a second freeze drying step to remove water without altering the physical structure. A stable structure of N-BCA with open and highly interconnected pores in the range of 90-160 μm was constructed. The N-BCA was stable in both water and PBS. The swelling ability of N-BCA in water was approximately 50 times its weight, which was about 6.5 times that of the freeze dried bacterial cellulose pellicles. N-BCA demonstrated no cytotoxicity against L929 mouse fibroblast cells. For long-term culture, N-BCA supported attachment, spreading, and proliferation of human gingival fibroblast (GF) on the surface. However, under static conditions, the cell migration and growth inside the scaffold were limited. Because of its biocompatibility and open macroporous structure, N-BCA could potentially be used as a scaffold for tissue engineering. PMID:26256335

  9. Composite electrospun gelatin fiber-alginate gel scaffolds for mechanically robust tissue engineered cornea.

    PubMed

    Tonsomboon, Khaow; Oyen, Michelle L

    2013-05-01

    A severe shortage of good quality donor cornea is now an international crisis in public health. Alternatives for donor tissue need to be urgently developed to meet the increasing demand for corneal transplantation. Hydrogels have been widely used as scaffolds for corneal tissue regeneration due to their large water content, similar to that of native tissue. However, these hydrogel scaffolds lack the fibrous structure that functions as a load-bearing component in the native tissue, resulting in poor mechanical performance. This work shows that mechanical properties of compliant hydrogels can be substantially enhanced with electrospun nanofiber reinforcement. Electrospun gelatin nanofibers were infiltrated with alginate hydrogels, yielding transparent fiber-reinforced hydrogels. Without prior crosslinking, electrospun gelatin nanofibers improved the tensile elastic modulus of the hydrogels from 78±19 kPa to 450±100 kPa. Stiffer hydrogels, with elastic modulus of 820±210 kPa, were obtained by crosslinking the gelatin fibers with carbodiimide hydrochloride in ethanol before the infiltration process, but at the expense of transparency. The developed fiber-reinforced hydrogels show great promise as mechanically robust scaffolds for corneal tissue engineering applications. PMID:23566770

  10. Alginate hydrogel enriched with enamel matrix derivative to target osteogenic cell differentiation in TiO2 scaffolds

    PubMed Central

    Pullisaar, Helen; Verket, Anders; Szoke, Krisztina; Tiainen, Hanna; Haugen, Håvard J; Brinchmann, Jan E; Reseland, Janne E

    2015-01-01

    The purpose of bone tissue engineering is to employ scaffolds, cells, and growth factors to facilitate healing of bone defects. The aim of this study was to assess the viability and osteogenic differentiation of primary human osteoblasts and adipose tissue–derived mesenchymal stem cells from various donors on titanium dioxide (TiO2) scaffolds coated with an alginate hydrogel enriched with enamel matrix derivative. Cells were harvested for quantitative reverse transcription polymerase chain reaction on days 14 and 21, and medium was collected on days 2, 14, and 21 for protein analyses. Neither coating with alginate hydrogel nor alginate hydrogel enriched with enamel matrix derivative induced a cytotoxic response. Enamel matrix derivative–enriched alginate hydrogel significantly increased the expression of osteoblast markers COL1A1, TNFRSF11B, and BGLAP and secretion of osteopontin in human osteoblasts, whereas osteogenic differentiation of human adipose tissue–derived mesenchymal stem cells seemed unaffected by enamel matrix derivative. The alginate hydrogel coating procedure may have potential for local delivery of enamel matrix derivative and other stimulatory factors for use in bone tissue engineering. PMID:26090086

  11. Enhanced in vitro osteoblast differentiation on TiO2 scaffold coated with alginate hydrogel containing simvastatin

    PubMed Central

    Pullisaar, Helen; Tiainen, Hanna; Landin, Maria A; Lyngstadaas, Ståle P; Reseland, Janne E; Østrup, Esben

    2013-01-01

    The aim of this study was to develop a three-dimensional porous bone graft material as vehicle for simvastatin delivery and to investigate its effect on primary human osteoblasts from three donors. Highly porous titanium dioxide (TiO2) scaffolds were submerged into simvastatin containing alginate solution. Microstructure of scaffolds, visualized by scanning electron microscopy and micro-computed tomography, revealed an evenly distributed alginate layer covering the surface of TiO2 scaffold struts. Progressive and sustained simvastatin release was observed for up to 19 days. No cytotoxic effects on osteoblasts were observed by scaffolds with simvastatin when compared to scaffolds without simvastatin. Expression of osteoblast markers (collagen type I alpha 1, alkaline phosphatase, bone morphogenetic protein 2, osteoprotegerin, vascular endothelial growth factor A and osteocalcin) was quantified using real-time reverse transcriptase–polymerase chain reaction. Secretion of osteoprotegerin, vascular endothelial growth factor A and osteocalcin was analysed by multiplex immunoassay (Luminex). The relative expression and secretion of osteocalcin was significantly increased by cells cultured on scaffolds with 10 µM simvastatin when compared to scaffolds without simvastatin after 21 days. In addition, secretion of vascular endothelial growth factor A was significantly enhanced from cells cultured on scaffolds with both 10 nM and 10 µM simvastatin when compared to scaffolds without simvastatin at day 21. In conclusion, the results indicate that simvastatin-coated TiO2 scaffolds can support a sustained release of simvastatin and induce osteoblast differentiation. The combination of the physical properties of TiO2 scaffolds with the osteogenic effect of simvastatin may represent a new strategy for bone regeneration in defects where immediate load is wanted or unavailable. PMID:24555011

  12. Manufacture of β-TCP/alginate scaffolds through a Fab@home model for application in bone tissue engineering.

    PubMed

    Diogo, G S; Gaspar, V M; Serra, I R; Fradique, R; Correia, I J

    2014-06-01

    The growing need to treat bone-related diseases in an elderly population compels the development of novel bone substitutes to improve patient quality of life. In this context, the advent of affordable and effective rapid prototyping equipment, such as the Fab@home plotter, has contributed to the development of novel scaffolds for bone tissue engineering. In this study, we report for the first time the use of a Fab@home plotter for the production of 3D scaffolds composed by beta-tricalcium phosphate (β-TCP)/alginate hybrid materials. β-TCP/alginate mixtures were used in a proportion of 50/50% (w/w), 30/70% (w/w) and 20/80% (w/w). The printing parameters were optimized to a nozzle diameter of 20 Gauge for the production of rigid scaffolds with pre-defined architectures. We observed that, despite using similar printing parameters, both the precision and resolution of the scaffolds were significantly affected by the blend's viscosity. In particular, we demonstrate that the higher viscosity of 50/50 scaffolds (150.0 ± 3.91 mPa s) provides a higher precision in the extrusion process. The physicochemical and biological characterization of the samples demonstrated that the 50/50 scaffolds possessed a resistance to compression comparable to that of native trabecular bone. Moreover, this particular formulation also exhibited a Young's modulus that was higher than that of trabecular bone. Scanning electron microscopy and fluorescence microscopy analysis revealed that osteoblasts were able to adhere, proliferate and also penetrate into the scaffold's architecture. Altogether, our findings suggest that the Fab@home printer can be employed in the manufacture of reproducible scaffolds, using a formulation 50/50 alginate-β-TCP that has suitable properties to be applied as bone substitutes in the future. PMID:24657988

  13. Emulsion templated scaffolds that include gelatin and glycosaminoglycans.

    PubMed

    Barbetta, Andrea; Massimi, Mara; Di Rosario, Biancalucia; Nardecchia, Stefania; De Colli, Marianna; Devirgiliis, Laura Conti; Dentini, Mariella

    2008-10-01

    Gelatin is one of the most commonly used biopolymer for creating cellular scaffolds due to its innocuous nature. To create stable gelatin scaffolds at physiological temperature (37 degrees C), chemical cross-linking is a necessary step. In a previous paper (Biomacromolecules 2006, 7, 3059-3068), cross-linking was carried out by either radical polymerization of the methacrylated derivative of gelatin (GMA) or through the formation of isopeptide bonds catalyzed by transglutaminase. The method of scaffold production was based on emulsion templating in which an organic phase is dispersed in the form of discrete droplets into a continuous aqueous solution of the biopolymer. Both kinds of scaffolds were tested as culture medium for hepatocytes. It turned out that the enzymatic cross-linked scaffold performed superiorily in this respect, even though it was mechanically less stable than the GMA scaffold. In the present paper, in an attempt to improve the biocompatibility of the GMA-based scaffold, biopolymers present in the extracellular matrix (ECM) were included in scaffold formulation, namely, chondroitin sulfate and hyaluronic acid. These biopolymers were derivatized with methacrylic moieties to undergo radical polymerization together with GMA. The morphology of the scaffolds was tuned to some extent by varying the volume fraction of the internal phase and to a larger extent by inducing a controlled destabilization of the precursor emulsion through the use of additives. In this way, scaffolds with 44% of the void volume attributable to voids with a diameter exceeding 60 microm and with 79% of the interconnect area attributable to interconnects with a diameter exceeding 20 microm in diameter could be successfully synthesized. To test whether the inclusion of ECM components into scaffold formulation resolves in an improvement of their biocompatibility with respect to GMA scaffolds, hepatocytes were seeded on both kinds of scaffolds and cell viability and function assays

  14. Peptide-incorporated 3D porous alginate scaffolds with enhanced osteogenesis for bone tissue engineering.

    PubMed

    Luo, Zuyuan; Yang, Yue; Deng, Yi; Sun, Yuhua; Yang, Hongtao; Wei, Shicheng

    2016-07-01

    Good bioactivity and osteogenesis of three-dimensional porous alginate scaffolds (PAS) are critical for bone tissue engineering. In this work, alginate and bone-forming peptide-1 (BFP-1), derived from bone morphogenetic protein-7 (BMP-7), have been combined together (without carbodiimide chemistry treatment) to develop peptide-incorporated PAS (p-PAS) for promoting bone repairing ability. The mechanical properties and SEM images show no difference between pure PAS and p-PAS. The release kinetics of the labeled peptide with 6-carboxy tetramethyl rhodamine from the PAS matrix suggests that the peptide is released in a relatively sustained manner. In the cell experiment, p-PAS show higher cell adhesion, spreading, proliferation and alkaline phosphatase (ALP) activity than the pristine PAS group, indicating that the BFP-1 released from p-PAS could significantly promote the aggregation and differentiation of osteoblasts, especially at 10μg/mL of trapped peptide concentration (p-PAS-10). Furthermore, p-PAS-10 was implanted into Beagle calvarial defects and bone regeneration was analyzed after 4 weeks. New bone formation was assessed by calcein and Masson's trichrome staining. The data reveal that p-PAS group exhibits significantly enhanced oseto-regenerative capability in vivo. The peptide-modified PAS with promoted bioactivity and osteogenic differentiation in vitro as well as bone formation ability in vivo could be promising tissue engineering materials for repairing and regeneration of bone defects. PMID:27022863

  15. Calcium/Cobalt Alginate Beads as Functional Scaffolds for Cartilage Tissue Engineering

    PubMed Central

    Focaroli, Stefano; Teti, Gabriella; Salvatore, Viviana; Orienti, Isabella; Falconi, Mirella

    2016-01-01

    Articular cartilage is a highly organized tissue with complex biomechanical properties. However, injuries to the cartilage usually lead to numerous health concerns and often culminate in disabling symptoms, due to the poor intrinsic capacity of this tissue for self-healing. Although various approaches are proposed for the regeneration of cartilage, its repair still represents an enormous challenge for orthopedic surgeons. The field of tissue engineering currently offers some of the most promising strategies for cartilage restoration, in which assorted biomaterials and cell-based therapies are combined to develop new therapeutic regimens for tissue replacement. The current study describes the in vitro behavior of human adipose-derived mesenchymal stem cells (hADSCs) encapsulated within calcium/cobalt (Ca/Co) alginate beads. These novel chondrogenesis-promoting scaffolds take advantage of the synergy between the alginate matrix and Co+2 ions, without employing costly growth factors (e.g., transforming growth factor betas (TGF-βs) or bone morphogenetic proteins (BMPs)) to direct hADSC differentiation into cartilage-producing chondrocytes. PMID:27057167

  16. Morphogenetically active scaffold for osteochondral repair (polyphosphate/alginate/N,O-carboxymethyl chitosan).

    PubMed

    Müller, W E; Neufurth, M; Wang, S; Tolba, E; Schröder, H C; Wang, X

    2016-01-01

    Here we describe a novel bioinspired hydrogel material that can be hardened with calcium ions to yield a scaffold material with viscoelastic properties matching those of cartilage. This material consists of a negatively charged biopolymer triplet, composed of morphogenetically active natural inorganic polyphosphate (polyP), along with the likewise biocompatible natural polymers N,O-carboxymethyl chitosan (N,O-CMC) and alginate. The porosity of the hardened scaffold material obtained after calcium exposure can be adjusted by varying the pre-processing conditions. Various compression tests were applied to determine the local (nanoindentation) and bulk mechanical properties (tensile/compression test system for force measurements) of the N,O-CMC-polyP-alginate material. Determinations of the Young's modulus revealed that the stiffness of this comparably water rich (and mouldable) material increases during successive compression cycles to values measured for native cartilage. The material not only comprises viscoelastic properties suitable for a cartilage substitute material, but also displays morphogenetic activity. It upregulates the expression of genes encoding for collagen type II and aggrecan, the major proteoglycan within the articular cartilage, in human chondrocytes, and the expression of alkaline phosphatase in human bone-like SaOS-2 cells, as revealed in RT qPCR experiments. Further, we demonstrate that the new polyP-based material can be applied for manufacturing 3D solid models of cartilage bone such as of the tibial epiphyseal plate and the superior articular cartilage surface. Since the material is resorbable and enhances the activity of cells involved in regeneration of cartilage tissue, this material has the potential to be used for artificial articular cartilage implants. PMID:26898843

  17. BIODEGRADABLE PHOTO-CROSSLINKED ALGINATE NANOFIBRE SCAFFOLDS WITH TUNEABLE PHYSICAL PROPERTIES, CELL ADHESIVITY AND GROWTH FACTOR RELEASE

    PubMed Central

    Jeong, Sung In; Jeon, Oju; Krebs, Melissa D.; Hill, Michael C.; Alsberg, Eben

    2012-01-01

    Nanofibrous scaffolds are of interest in tissue engineering due to their high surface area to volume ratio, interconnected pores, and architectural similarity to the native extracellular matrix. Our laboratory recently developed a biodegradable, photo-crosslinkable alginate biopolymer. Here, we show the capacity of the material to be electrospun into a nanofibrous matrix, and the ability to enhance cell adhesion and proliferation on these matrices by covalent modification with cell adhesion peptides. Additionally, the potential of covalently incorporating heparin into the hydrogels during the photopolymerisation process to sustain the release of a heparin binding growth factor via affinity interactions was demonstrated. Electrospun photo-crosslinkable alginate nanofibrous scaffolds endowed with cell adhesion ligands and controlled delivery of growth factors may allow for improved regulation of cell behaviour for regenerative medicine. PMID:23070945

  18. Proliferation and enrichment of CD133+ glioblastoma cancer stem cells on 3D chitosan-alginate scaffolds

    PubMed Central

    Kievit, Forrest M.; Florczyk, Stephen J.; Leung, Matthew C.; Wang, Kui; Wu, Jennifer D.; Silber, John R.; Ellenbogen, Richard G.; Lee, Jerry S.H.; Zhang, Miqin

    2014-01-01

    Emerging evidence implicates cancer stem cells (CSCs) as primary determinants of the clinical behavior of human cancers, representing an ideal target for next-generation anticancer therapies. However CSCs are difficult to propagate in vitro, severely limiting the study of CSC biology and drug development. Here we report that growing cells from glioblastoma (GBM) cell lines on three dimensional (3D) porous chitosan-alginate (CA) scaffolds dramatically promotes the proliferation and enrichment of cells possessing the hallmarks of CSCs. CA scaffold-grown cells were found more tumorigenic in nude mouse xenografts than cells grown from monolayers. Growing in CA scaffolds rapidly promoted expression of genes involved in the epithelial-to-mesenchymal transition that has been implicated in the genesis of CSCs. Our results indicate that CA scaffolds have utility as a simple and inexpensive means to cultivate CSCs in vitro in support of studies to understand CSC biology and develop more effective anti-cancer therapies. PMID:25109438

  19. Human hepatoma cell lines on gas foaming templated alginate scaffolds for in vitro drug-drug interaction and metabolism studies.

    PubMed

    Stampella, A; Rizzitelli, G; Donati, F; Mazzarino, M; de la Torre, X; Botrè, F; Giardi, M F; Dentini, M; Barbetta, A; Massimi, M

    2015-12-25

    Liver in vitro systems that allow reliable prediction of major human in vivo metabolic pathways have a significant impact in drug screening and drug metabolism research. In the present study, a novel porous scaffold composed of alginate was prepared by employing a gas-in-liquid foaming approach. Galactose residues were introduced on scaffold surfaces to promote cell adhesion and to enhance liver specific functions of the entrapped HepG2/C3A cells. Hepatoma cells in the gal-alginate scaffold showed higher levels of liver specific products (albumin and urea) and were more responsive to specific inducers (e.g. dexamethasone) and inhibitors (e.g. ketoconazole) of the CYP3A4 system than in conventional monolayer culture. HepG2/C3A cells were also more efficient in terms of rapid elimination of testosterone, used as a model substance, at rates comparable to those of in vivo excretion. In addition, an improvement in metabolism of testosterone, in terms of phase II metabolite formation, was also observed when the more differentiated HepaRG cells were used. Together the data suggest that hepatocyte/gas templated alginate-systems provide an innovative high throughput platform for in vitro drug metabolism and drug-drug interaction studies, with broad fields of application, and might provide a valid tool for minimizing animal use in preclinical testing of human relevance. PMID:26456671

  20. Self-crosslinked oxidized alginate/gelatin hydrogel as injectable, adhesive biomimetic scaffolds for cartilage regeneration.

    PubMed

    Balakrishnan, Biji; Joshi, Nitin; Jayakrishnan, Athipettah; Banerjee, Rinti

    2014-08-01

    Biopolymeric hydrogels that mimic the properties of extracellular matrix have great potential in promoting cellular migration and proliferation for tissue regeneration. The authors reported earlier that rapidly gelling, biodegradable, injectable hydrogels can be prepared by self-crosslinking of periodate oxidized alginate and gelatin in the presence of borax, without using any toxic crosslinking agents. The present paper investigates the suitability of this hydrogel as a minimally invasive injectable, cell-attractive and adhesive scaffold for cartilage tissue engineering for the treatment of osteoarthritis. Time and frequency sweep rheology analysis confirmed gel formation within 20s. The hydrogel integrated well with the cartilage tissue, with a burst pressure of 70±3mmHg, indicating its adhesive nature. Hydrogel induced negligible inflammatory and oxidative stress responses, a prerequisite for the management and treatment of osteoarthritis. Scanning electron microscopy images of primary murine chondrocytes encapsulated within the matrix revealed attachment of cells onto the hydrogel matrix. Chondrocytes demonstrated viability, proliferation and migration within the matrix, while maintaining their phenotype, as seen by expression of collagen type II and aggrecan, and functionality, as seen by enhanced glycosoaminoglycan (GAG) deposition with time. DNA content and GAG deposition of chondrocytes within the matrix can be tuned by incorporation of bioactive signaling molecules such as dexamethasone, chondroitin sulphate, platelet derived growth factor (PDGF-BB) and combination of these three agents. The results suggest that self-crosslinked oxidized alginate/gelatin hydrogel may be a promising injectable, cell-attracting adhesive matrix for neo-cartilage formation in the management and treatment of osteoarthritis. PMID:24811827

  1. Enhanced Healing of Rat Calvarial Defects with MSCs Loaded on BMP-2 Releasing Chitosan/Alginate/Hydroxyapatite Scaffolds

    PubMed Central

    He, Xiaoning; Liu, Yang; Yuan, Xue; Lu, Li

    2014-01-01

    In this study, we designed a chitosan/alginate/hydroxyapatite scaffold as a carrier for recombinant BMP-2 (CAH/B2), and evaluated the release kinetics of BMP-2. We evaluated the effect of the CAH/B2 scaffold on the viability and differentiation of bone marrow mesenchymal stem cells (MSCs) by scanning electron microscopy, MTS, ALP assay, alizarin-red staining and qRT-PCR. Moreover, MSCs were seeded on scaffolds and used in a 8 mm rat calvarial defect model. New bone formation was assessed by radiology, hematoxylin and eosin staining 12 weeks postoperatively. We found the release kinetics of BMP-2 from the CAH/B2 scaffold were delayed compared with those from collagen gel, which is widely used for BMP-2 delivery. The BMP-2 released from the scaffold increased MSC differentiation and did not show any cytotoxicity. MSCs exhibited greater ALP activity as well as stronger calcium mineral deposition, and the bone-related markers Col1α, osteopontin, and osteocalcin were upregulated. Analysis of in vivo bone formation showed that the CAH/B2 scaffold induced more bone formation than other groups. This study demonstrates that CAH/B2 scaffolds might be useful for delivering osteogenic BMP-2 protein and present a promising bone regeneration strategy. PMID:25084008

  2. 3D Porous Calcium-Alginate Scaffolds Cell Culture System Improved Human Osteoblast Cell Clusters for Cell Therapy

    PubMed Central

    Chen, Ching-Yun; Ke, Cherng-Jyh; Yen, Ko-Chung; Hsieh, Hui-Chen; Sun, Jui-Sheng; Lin, Feng-Huei

    2015-01-01

    Age-related orthopedic disorders and bone defects have become a critical public health issue, and cell-based therapy is potentially a novel solution for issues surrounding bone tissue engineering and regenerative medicine. Long-term cultures of primary bone cells exhibit phenotypic and functional degeneration; therefore, culturing cells or tissues suitable for clinical use remain a challenge. A platform consisting of human osteoblasts (hOBs), calcium-alginate (Ca-Alginate) scaffolds, and a self-made bioreactor system was established for autologous transplantation of human osteoblast cell clusters. The Ca-Alginate scaffold facilitated the growth and differentiation of human bone cell clusters, and the functionally-closed process bioreactor system supplied the soluble nutrients and osteogenic signals required to maintain the cell viability. This system preserved the proliferative ability of cells and cell viability and up-regulated bone-related gene expression and biological apatite crystals formation. The bone-like tissue generated could be extracted by removal of calcium ions via ethylenediaminetetraacetic acid (EDTA) chelation, and exhibited a size suitable for injection. The described strategy could be used in therapeutic application and opens new avenues for surgical interventions to correct skeletal defects. PMID:25825603

  3. Minimally traumatic alveolar ridge augmentation with a tunnel injectable thermo-sensitive alginate scaffold

    PubMed Central

    LI, Yifen; FANG, Xiaoqian; JIANG, Ting

    2015-01-01

    Injectable bone substitutes and techniques have been developed for use in minimally invasive procedures for bone augmentation. Objective : To develop a novel injectable thermo-sensitive alginate hydrogel (TSAH) as a scaffold to induce bone regeneration, using a minimally invasive tunnelling technique. Material and Methods : An injectable TSAH was prepared from a copolymer solution of 8.0 wt% Poly(N-isopropylacrylamide) (PNIPAAm) and 8.0 wt% AAlg-g-PNIPAAm. In vitro properties of the material, such as its microstructure and the sustained release of recombinant human bone morphogenetic protein-2 (rhBMP-2), were investigated. Then, with the subperiosteal tunnelling technique, this material, carrying rhBMP-2, was injected under the labial periosteum of the maxillary anterior alveolar ridge in a rabbit model. New bone formation was evaluated by means of X-ray, micro-computed tomography (micro-CT), fluorescence labelling, histological study, and immunohistochemistry study. Results : The material exhibited good injectability and thermo-irreversible properties. SEM showed an interconnected porous microstructure of the TSAH. The result of ALP activity indicated sustained delivery of BMP-2 from the TSAH from days 3 to 15. In a rabbit model, both TSAH and TSAH/rhBMP-2 induced alveolar ridge augmentation. The percentage of mineralised tissue in the TSAH/rhBMP-2 group (41.6±3.79%) was significantly higher than in the TSAH group (31.3±7.21%; p<0.05). The density of the regenerating tissue was higher in the TSAH/rhBMP-2 group than in the other groups (TSAH group, positive control, blank control; p<0.05). Conclusions : The TSAH provided convenient handling properties for clinical application. To some extent, TSAH could induce ridge augmentation and mineral deposition, which can be enhanced when combined with rhBMP-2 for a minimally invasive tunnelling injection. PMID:26018314

  4. Preparation and characterization of nano-sized hydroxyapatite/alginate/chitosan composite scaffolds for bone tissue engineering.

    PubMed

    Kim, Hye-Lee; Jung, Gil-Yong; Yoon, Jun-Ho; Han, Jung-Suk; Park, Yoon-Jeong; Kim, Do-Gyoon; Zhang, Miqin; Kim, Dae-Joon

    2015-09-01

    The aim of this study was to develop chitosan composite scaffolds with high strength and controlled pore structures by homogenously dispersed nano-sized hydroxyapatite (nano-HAp) powders. In the fabrication of composite scaffolds, nano-HAp powders distributed in an alginate (AG) solution with a pH higher than 10 were mixed with a chitosan (CS) solution and then freeze dried. While the HAp content increased up to 70 wt.%, the compressive strength and the elastic modulus of the composite scaffolds significantly increased from 0.27 MPa and 4.42 MPa to 0.68 MPa and 13.35 MPa, respectively. Higher content of the HAp also helped develop more differentiation and mineralization of the MC3T3-E1 cells on the composite scaffolds. The uniform pore structure and the excellent mechanical properties of the HAp/CS composite scaffolds likely resulted from the use of the AG solution at pH 10 as a dispersant for the nano-HAp powders. PMID:26046263

  5. Macro- and micro-designed chitosan-alginate scaffold architecture by three-dimensional printing and directional freezing.

    PubMed

    Reed, Stephanie; Lau, Grace; Delattre, Benjamin; Lopez, David Don; Tomsia, Antoni P; Wu, Benjamin M

    2016-03-01

    While many tissue-engineered constructs aim to treat cartilage defects, most involve chondrocyte or stem cell seeding on scaffolds. The clinical application of cell-based techniques is limited due to the cost of maintaining cellular constructs on the shelf, potential immune response to allogeneic cell lines, and autologous chondrocyte sources requiring biopsy from already diseased or injured, scarce tissue. An acellular scaffold that can induce endogenous influx and homogeneous distribution of native stem cells from bone marrow holds great promise for cartilage regeneration. This study aims to develop such an acellular scaffold using designed, channeled architecture that simultaneously models the native zones of articular cartilage and subchondral bone. Highly porous, hydrophilic chitosan-alginate (Ch-Al) scaffolds were fabricated in three-dimensionally printed (3DP) molds designed to create millimeter scale macro-channels. Different polymer preform casting techniques were employed to produce scaffolds from both negative and positive 3DP molds. Macro-channeled scaffolds improved cell suspension distribution and uptake overly randomly porous scaffolds, with a wicking volumetric flow rate of 445.6 ± 30.3 mm(3) s(-1) for aqueous solutions and 177 ± 16 mm(3) s(-1) for blood. Additionally, directional freezing was applied to Ch-Al scaffolds, resulting in lamellar pores measuring 300 μm and 50 μm on the long and short axes, thus creating micrometer scale micro-channels. After directionally freezing Ch-Al solution cast in 3DP molds, the combined macro- and micro-channeled scaffold architecture enhanced cell suspension uptake beyond either macro- or micro-channels alone, reaching a volumetric flow rate of 1782.1 ± 48 mm(3) s(-1) for aqueous solutions and 440.9 ± 0.5 mm(3) s(-1) for blood. By combining 3DP and directional freezing, we can control the micro- and macro-architecture of Ch-Al to drastically improve cell influx into and distribution within the scaffold

  6. Study of Carbon Nano-Tubes Effects on the Chondrogenesis of Human Adipose Derived Stem Cells in Alginate Scaffold

    PubMed Central

    Valiani, Ali; Hashemibeni, Batool; Esfandiary, Ebrahim; Ansar, Malek Masoud; Kazemi, Mohammad; Esmaeili, Nafiseh

    2014-01-01

    Background: Osteoarthritis is one of the most common diseases in middle-aged populations in the World and could become the fourth principal cause of disability by the year 2020. One of the critical properties for cartilage tissue engineering (TE) is the ability of scaffolds to closely mimic the extracellular matrix and bond to the host tissue. Therefore, TE has been presented as a technique to introduce the best combination of cells and biomaterial scaffold and to stimulate growth factors to produce a cartilage tissue resembling natural articular cartilage. The aim of study is to improve differentiation of adipose derived stem cells (ADSCs) into chondrocytes in order to provide a safe and modern treatment for patients suffering from cartilage damages. Methods: After functionalization, dispersions and sterilizing carbon nano-tubes (CNTs), a new type of nanocomposite gel was prepared from water-soluble CNTs and alginate. ADSCs seeded in 1.5% alginate scaffold and cultured in chondrogenic media with and without transforming growth factor-β1 (TGF-β1) for 7 and 14 days. The genes expression of sex determining region Y-box 9 (SOX9), types II and X collagens was assessed by real-time polymerase chain reaction and the amount of aggrecan (AGC) and type I collagen was measured by ELISA. Results: Our findings showed that the expression of essential cartilage markers, SOX9, type II collagen and AGC, in differentiated ADSCs at the concentration of 1 μg/ml CNTs in the presence of TGF-β1 were significantly increased in comparison with the control group (P < 0.001). Meanwhile, type X collagen expression and also type I collagen production were significantly decreased (P < 0.001). Conclusions: The results showed that utilized three-dimensional scaffold had a brilliant effect in promoting gene expression of chondrogenesis. PMID:25104993

  7. Development of porous alginate-based scaffolds covalently cross-linked through a peroxidase-catalyzed reaction.

    PubMed

    Sakai, Shinji; Kawakami, Koei

    2011-01-01

    Porous scaffolds are important in tissue engineering. We developed porous scaffolds from the hydrogels of an alginate derivative bearing phenolic hydroxyl groups. The hydrogels were prepared using horseradish peroxidase (HRP) to catalyze the cross-linking between the phenolic hydroxyl groups. A porous structure with a pore size of approx. 200 μm was developed through simultaneous water-extraction and ionic cross-linking by calcium ions by soaking frozen hydrogels in the mixture of ethanol and CaCl2 solution at -20°C. Due to the existence of the covalent cross-links developed through the enzymatic reaction, the porous form had a higher stability from a loss of cross-linked calcium ions than that obtained from non-modified sodium alginate (Na-Alg). The porous specimen developed from the hydrogel obtained with 10 U/ml HRP and 10 mM H2O2 showed about 1.5-times greater repulsion forces than those detected for the porous specimen obtained from Na-Alg toward compressions. No harmful effects of the enzymatically cross-linked specimens were detected on the growth and morphology of the entrapped cells: cells in the enzymatically cross-linked specimens showed almost the same growth profile and morphology with those in the porous specimen obtained from Na-Alg. PMID:21144141

  8. Enhanced cellular activities of polycaprolactone/alginate-based cell-laden hierarchical scaffolds for hard tissue engineering applications.

    PubMed

    Lee, HyeongJin; Kim, GeunHyung

    2014-09-15

    Biomedical scaffolds have been widely investigated because they are essential for support and promotion of cell adhesion, proliferation and differentiation in three-dimensional (3D) structures. An ideal scaffold should be highly porous to enable efficient nutrient and oxygen transfer and have a 3D structure that provides optimal micro-environmental conditions for the seeded cells to obtain homogeneous growth after a long culture period. In this study, new hierarchical osteoblast-like cell (MG-63)-laden scaffolds consisting of micro-sized struts/inter-layered micro-nanofibres and cell-laden hydrogel struts with mechanically stable and biologically superior properties were introduced. Poly(ethylene oxide) (PEO) was used as a sacrificial component to generate pores within the cell-laden hydrogel struts to attain a homogeneous cell distribution and rapid cell growth in the scaffold interior. The alginate-based cell-laden struts with PEO induced fast/homogeneous cell release, in contrast to nonporous cell-laden struts. Various weight fractions (0.5, 1, 2, 3 and 3.5 wt%) of PEO were used, of which 2 wt% PEO in the cell-laden strut resulted in the most appropriate cell release and enhanced biological activities (cell proliferation and calcium deposition), compared to nonporous cell-laden struts. PMID:24974244

  9. Facile fabrication of poly(L-lactic acid) microsphere-incorporated calcium alginate/hydroxyapatite porous scaffolds based on Pickering emulsion templates.

    PubMed

    Hu, Yang; Ma, Shanshan; Yang, Zhuohong; Zhou, Wuyi; Du, Zhengshan; Huang, Jian; Yi, Huan; Wang, Chaoyang

    2016-04-01

    In this study, we develop a facile one-pot approach to the fabrication of poly(L-lactic acid) (PLLA) microsphere-incorporated calcium alginate (ALG-Ca)/hydroxyapatite (HAp) porous scaffolds based on HAp nanoparticle-stabilized oil-in-water Pickering emulsion templates, which contain alginate in the aqueous phase and PLLA in the oil phase. The emulsion aqueous phase is solidified by in situ gelation of alginate with Ca(2+) released from HAp by decreasing pH with slow hydrolysis of d-gluconic acid δ-lactone (GDL) to produce emulsion droplet-incorporated gels, followed by freeze-drying to form porous scaffolds containing microspheres. The pore structure of porous scaffolds can be adjusted by varying the HAp or GDL concentration. The compressive tests show that the increase of HAp or GDL concentration is beneficial to improve the compressive property of porous scaffolds, while the excessive HAp can lead to the decrease in compressive property. Moreover, the swelling behavior studies display that the swelling ratios of porous scaffolds reduce with increasing HAp or GDL concentration. Furthermore, hydrophobic drug ibuprofen (IBU) and hydrophilic drug bovine serum albumin (BSA) are loaded into the microspheres and scaffold matrix, respectively. In vitro drug release results indicate that BSA has a rapid release while IBU has a sustained release in the dual drug-loaded scaffolds. In vitro cell culture experiments verify that mouse bone mesenchymal stem cells can proliferate on the porous scaffolds well, indicating the good biocompatibility of porous scaffolds. All these results demonstrate that the PLLA microsphere-incorporated ALG-Ca/HAp porous scaffolds have a promising potential for tissue engineering and drug delivery applications. PMID:26774574

  10. Mechanical properties, biological behaviour and drug release capability of nano TiO2-HAp-Alginate composite scaffolds for potential application as bone implant material.

    PubMed

    Naik, Kshipra; Chandran, V Girish; Rajashekaran, Raghavan; Waigaonkar, Sachin; Kowshik, Meenal

    2016-09-01

    Nanocomposite scaffolds of TiO2 and hydroxyapatite nanoparticles with alginate as the binding agent were fabricated using the freeze drying technique. TiO2, hydroxyapatite and alginate were used in the ratio of 1:1:4. The scaffolds were characterized using X-ray diffraction, fourier transform infrared spectroscopy, and scanning electron microscopy. The biocompatibility of the scaffolds was evaluated using cell adhesion and MTT assay on osteosarcoma (MG-63) cells. Scanning electron microscopy analysis revealed that cells adhered to the surface of the scaffolds with good spreading. The mechanical properties of the scaffolds were investigated using dynamic mechanical analysis. The swelling ability, porosity, in vitro degradation, and biomineralization of the scaffolds were also evaluated. The results indicated controlled swelling, limited degradation, and enhanced biomineralization. Further, drug delivery studies of the scaffolds using the chemotherapeutic drug methotrexate exhibited an ideal drug release profile. These scaffolds are proposed as potential candidates for bone tissue engineering and drug delivery applications. PMID:27485954

  11. Chitosan silk-based three-dimensional scaffolds containing gentamicin-encapsulated calcium alginate beads for drug administration and blood compatibility.

    PubMed

    Mehta, Abijeet Singh; Singh, Brijesh K; Singh, Nandita; Archana, D; Snigdha, Kirti; Harniman, Robert; Rahatekar, Sameer S; Tewari, R P; Dutta, P K

    2015-04-01

    In the present study gentamicin was encapsulated within calcium alginate beads and incorporated into porous chitosan, gelatin, double-hybrid silk fibroin, chitosan/gelatin and double-hybrid silk fibroin/chitosan scaffolds. Physiochemical, morphological and biological properties of fabricated amenable model systems were evaluated, revealing hemocompatible nature of double-hybrid silk fibroin/chitosan and double-hybrid silk fibroin scaffolds of hemolysis %<5 and porosity >85%. Fourier transform infrared results confirmed the blend formation and scanning electron microscope images showed good interconnectivity. Double-hybrid silk fibroin/chitosan-blended scaffold shows higher compressive strength and compressive modulus than other fabricated scaffolds. A comparative drug release profile of fabricated scaffolds revealed that double-hybrid silk fibroin/chitosan scaffold is a pertinent model system because of its prolonged drug release, optimal hemocompatability and high compressive modulus. PMID:25492055

  12. Cell-Laden Poly(ɛ-caprolactone)/Alginate Hybrid Scaffolds Fabricated by an Aerosol Cross-Linking Process for Obtaining Homogeneous Cell Distribution: Fabrication, Seeding Efficiency, and Cell Proliferation and Distribution

    PubMed Central

    Lee, HyeongJin; Ahn, SeungHyun; Bonassar, Lawrence J.; Chun, Wook

    2013-01-01

    Generally, solid-freeform fabricated scaffolds show a controllable pore structure (pore size, porosity, pore connectivity, and permeability) and mechanical properties by using computer-aided techniques. Although the scaffolds can provide repeated and appropriate pore structures for tissue regeneration, they have a low biological activity, such as low cell-seeding efficiency and nonuniform cell density in the scaffold interior after a long culture period, due to a large pore size and completely open pores. Here we fabricated three different poly(ɛ-caprolactone) (PCL)/alginate scaffolds: (1) a rapid prototyped porous PCL scaffold coated with an alginate, (2) the same PCL scaffold coated with a mixture of alginate and cells, and (3) a multidispensed hybrid PCL/alginate scaffold embedded with cell-laden alginate struts. The three scaffolds had similar micropore structures (pore size=430–580 μm, porosity=62%–68%, square pore shape). Preosteoblast cells (MC3T3-E1) were used at the same cell density in each scaffold. By measuring cell-seeding efficiency, cell viability, and cell distribution after various periods of culturing, we sought to determine which scaffold was more appropriate for homogeneously regenerated tissues. PMID:23469894

  13. Shape-memory porous alginate scaffolds for regeneration of the annulus fibrosus: effect of TGF-β3 supplementation and oxygen culture conditions.

    PubMed

    Guillaume, Olivier; Daly, Andrew; Lennon, Kerri; Gansau, Jennifer; Buckley, Shane F; Buckley, Conor T

    2014-05-01

    Disc herniation as a result of degenerative or traumatic injury is believed to be the primary instigator of low back pain. At present there is a lack of viable treatment options to repair damaged annulus fibrosus (AF) tissue. Developing alternative strategies to fill and repair ruptured AF tissue is a key challenge. In this work we developed a porous alginate scaffold with shape-memory properties which can be delivered using minimally invasive approaches and recover its original geometry once hydrated. Covalently cross-linked alginate hydrogels were created using carbodiimide chemistry, followed by a freeze-drying step to impart porosity and create porous scaffolds. Results showed that porous alginate scaffolds exhibited shape-memory recovery and mechanical behaviour that could be modulated depending on the cross-linker concentrations. The scaffold can be repeatedly compressed and expanded, which provides the potential to deliver the biomaterial directly to the damaged area of the AF tissue. In vitro experiments demonstrated that scaffolds were cytocompatible and supported cell seeding, penetration and proliferation under intervertebral-disc-like microenvironmental conditions (low glucose media and low oxygen concentration). Extracellular matrix (ECM) was secreted by AF cells with TGF-β3 stimulation and after 21days had filled the porous scaffold network. This biological matrix was rich in sulfated glycosaminoglycan and collagen type I, which are the main compounds of native AF tissue. Successful ECM deposition was also confirmed by the increase in the peak stress of the scaffold. However, the immaturity of the matrix network after only 21days of in vitro culture was not sufficient to attain native AF tissue mechanical properties. The ability to deliver porous scaffolds using minimal invasive approaches that can potentially promote the regeneration of AF defects provides an exciting new avenue for disc repair. PMID:24380722

  14. Cell-secreted extracellular matrix formation and differentiation of adipose-derived stem cells in 3D alginate scaffolds with tunable properties.

    PubMed

    Guneta, Vipra; Loh, Qiu Li; Choong, Cleo

    2016-05-01

    Three dimensional (3D) alginate scaffolds with tunable mechanical and structural properties are explored for investigating the effect of the scaffold properties on stem cell behavior and extracellular matrix (ECM) formation. Varying concentrations of crosslinker (20 - 60%) are used to tune the stiffness, porosity, and the pore sizes of the scaffolds post-fabrication. Enhanced cell proliferation and adipogenesis occur in scaffolds with 3.52 ± 0.59 kPa stiffness, 87.54 ± 18.33% porosity and 68.33 ± 0.88 μm pore size. On the other hand, cells in scaffolds with stiffness greater than 11.61 ± 1.74 kPa, porosity less than 71.98 ± 6.25%, and pore size less than 64.15 ± 4.34 μm preferentially undergo osteogenesis. When cultured in differentiation media, adipose-derived stem cells (ASCs) undergoing terminal adipogenesis in 20% firming buffer (FB) scaffolds and osteogenesis in 40% and 60% FB scaffolds show the highest secretion of collagen as compared to other groups of scaffolds. Overall, this study demonstrates the three-way relationship between 3D scaffolds, ECM composition, and stem cell differentiation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1090-1101, 2016. PMID:26749566

  15. Bone Regeneration Potential of Stem Cells Derived from Periodontal Ligament or Gingival Tissue Sources Encapsulated in RGD-Modified Alginate Scaffold

    PubMed Central

    Chen, Chider; Xu, Xingtian; Akiyama, Kentaro; Ansari, Sahar; Zadeh, Homayoun H.; Shi, Songtao

    2014-01-01

    Mesenchymal stem cells (MSCs) provide an advantageous alternative therapeutic option for bone regeneration in comparison to current treatment modalities. However, delivering MSCs to the defect site while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated bone regeneration. Here, we tested the bone regeneration capacity of periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs) encapsulated in a novel RGD- (arginine-glycine-aspartic acid tripeptide) coupled alginate microencapsulation system in vitro and in vivo. Five-millimeter-diameter critical-size calvarial defects were created in immunocompromised mice and PDLSCs and GMSCs encapsulated in RGD-modified alginate microspheres were transplanted into the defect sites. New bone formation was assessed using microcomputed tomography and histological analyses 8 weeks after transplantation. Results confirmed that our microencapsulation system significantly enhanced MSC viability and osteogenic differentiation in vitro compared with non-RGD-containing alginate hydrogel microspheres with larger diameters. Results confirmed that PDLSCs were able to repair the calvarial defects by promoting the formation of mineralized tissue, while GMSCs showed significantly lower osteogenic differentiation capability. Further, results revealed that RGD-coupled alginate scaffold facilitated the differentiation of oral MSCs toward an osteoblast lineage in vitro and in vivo, as assessed by expression of osteogenic markers Runx2, ALP, and osteocalcin. In conclusion, these results for the first time demonstrated that MSCs derived from orofacial tissue encapsulated in RGD-modified alginate scaffold show promise for craniofacial bone regeneration. This treatment modality has many potential dental and orthopedic applications. PMID:24070211

  16. Bone regeneration potential of stem cells derived from periodontal ligament or gingival tissue sources encapsulated in RGD-modified alginate scaffold.

    PubMed

    Moshaverinia, Alireza; Chen, Chider; Xu, Xingtian; Akiyama, Kentaro; Ansari, Sahar; Zadeh, Homayoun H; Shi, Songtao

    2014-02-01

    Mesenchymal stem cells (MSCs) provide an advantageous alternative therapeutic option for bone regeneration in comparison to current treatment modalities. However, delivering MSCs to the defect site while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated bone regeneration. Here, we tested the bone regeneration capacity of periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs) encapsulated in a novel RGD- (arginine-glycine-aspartic acid tripeptide) coupled alginate microencapsulation system in vitro and in vivo. Five-millimeter-diameter critical-size calvarial defects were created in immunocompromised mice and PDLSCs and GMSCs encapsulated in RGD-modified alginate microspheres were transplanted into the defect sites. New bone formation was assessed using microcomputed tomography and histological analyses 8 weeks after transplantation. Results confirmed that our microencapsulation system significantly enhanced MSC viability and osteogenic differentiation in vitro compared with non-RGD-containing alginate hydrogel microspheres with larger diameters. Results confirmed that PDLSCs were able to repair the calvarial defects by promoting the formation of mineralized tissue, while GMSCs showed significantly lower osteogenic differentiation capability. Further, results revealed that RGD-coupled alginate scaffold facilitated the differentiation of oral MSCs toward an osteoblast lineage in vitro and in vivo, as assessed by expression of osteogenic markers Runx2, ALP, and osteocalcin. In conclusion, these results for the first time demonstrated that MSCs derived from orofacial tissue encapsulated in RGD-modified alginate scaffold show promise for craniofacial bone regeneration. This treatment modality has many potential dental and orthopedic applications. PMID:24070211

  17. Silk fibroin/sodium alginate composite nano-fibrous scaffold prepared through thermally induced phase-separation (TIPS) method for biomedical applications.

    PubMed

    Zhang, Haiping; Liu, Xiaotian; Yang, Mingying; Zhu, Liangjun

    2015-10-01

    To mimic the natural fibrous structure of the tissue extracellular matrix, a nano-fibrous silk fibroin (SF)/sodium alginate (SA) composite scaffold was fabricated by a thermally-induced phase-separation method. The effects of SF/SA ratio on the structure and the porosity of the composite scaffolds were examined. Scanning electron microscopy and porosity results showed that the 5SF/1SA and 3SF/1SA scaffolds possessed an excellent nano-fibrous structure and a porosity of more than 90%. Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry results indicated the physical interaction between SF and SA molecules and their good compatibility in the 5SF/1SA and 3SF/1SA scaffolds, whereas they showed less compatibility in the 1SF/1SA scaffold. Cell culture results showed that MG-63 cells can attach and grow well on the surface of the SF/SA scaffolds. The nano-fibrous SF/SA scaffold can be potentially used in tissue engineering. PMID:26117733

  18. 3D Porous Chitosan-Alginate Scaffolds as an In Vitro Model for Evaluating Nanoparticle-Mediated Tumor Targeting and Gene Delivery to Prostate Cancer.

    PubMed

    Wang, Kui; Kievit, Forrest M; Florczyk, Stephen J; Stephen, Zachary R; Zhang, Miqin

    2015-10-12

    Cationic nanoparticles (NPs) for targeted gene delivery are conventionally evaluated using 2D in vitro cultures. However, this does not translate well to corresponding in vivo studies because of the marked difference in NP behavior in the presence of the tumor microenvironment. In this study, we investigated whether prostate cancer (PCa) cells cultured in three-dimensional (3D) chitosan-alginate (CA) porous scaffolds could model cationic NP-mediated gene targeted delivery to tumors in vitro. We assessed in vitro tumor cell proliferation, formation of tumor spheroids, and expression of marker genes that promote tumor malignancy in CA scaffolds. The efficacy of NP-targeted gene delivery was evaluated in PCa cells in 2D cultures, PCa tumor spheroids grown in CA scaffolds, and PCa tumors in a mouse TRAMP-C2 flank tumor model. PCa cells cultured in CA scaffolds grew into tumor spheroids and displayed characteristics of higher malignancy as compared to those in 2D cultures. Significantly, targeted gene delivery was only observed in cells cultured in CA scaffolds, whereas cells cultured on 2D plates showed no difference in gene delivery between targeted and nontarget control NPs. In vivo NP evaluation confirmed targeted gene delivery, indicating that only CA scaffolds correctly modeled NP-mediated targeted delivery in vivo. These findings suggest that CA scaffolds serve as a better in vitro platform than 2D cultures for evaluation of NP-mediated targeted gene delivery to PCa. PMID:26347946

  19. Cells (MC3T3-E1)-laden alginate scaffolds fabricated by a modified solid-freeform fabrication process supplemented with an aerosol spraying.

    PubMed

    Ahn, SeungHyun; Lee, HyeongJin; Bonassar, Lawrence J; Kim, GeunHyung

    2012-09-10

    In this study, we propose a new cell encapsulation method consisting of a dispensing method and an aerosol-spraying method. The aerosol spray using a cross-linking agent, calcium chloride (CaCl(2)), was used to control the surface gelation of dispensed alginate struts during dispensing. To show the feasibility of the method, we used preosteoblast (MC3T3-E1) cells. By changing the relationship between the various dispensing/aerosol-spraying conditions and cell viability, we could determine the optimal cell-dispensing process: a nozzle size (240 μm) and an aerosol spray flow rate (0.93 ± 0.12 mL min(-1)), 10 mm s(-1) nozzle moving speed, a 10 wt % concentration of CaCl(2) in the aerosol solution, and 2 wt % concentration of CaCl(2) in the second cross-linking process. Based on these optimized process conditions, we successfully fabricated a three-dimensional, pore-structured, cell-laden alginate scaffold of 20 × 20 × 4.6 mm(3) and 84% cell viability. During long cell culture periods (16, 25, 33, and 45 days), the preosteoblasts in the alginate scaffold survived and proliferated well. PMID:22913233

  20. Thermogelling bioadhesive scaffolds for intervertebral disk tissue engineering: preliminary in vitro comparison of aldehyde-based versus alginate microparticle-mediated adhesion.

    PubMed

    Wiltsey, C; Christiani, T; Williams, J; Scaramazza, J; Van Sciver, C; Toomer, K; Sheehan, J; Branda, A; Nitzl, A; England, E; Kadlowec, J; Iftode, C; Vernengo, J

    2015-04-01

    Tissue engineering of certain load-bearing parts of the body can be dependent on scaffold adhesion or integration with the surrounding tissue to prevent dislocation. One such area is the regeneration of the intervertebral disc (IVD). In this work, poly(N-isopropylacrylamide) (PNIPAAm) was grafted with chondroitin sulfate (CS) (PNIPAAm-g-CS) and blended with aldehyde-modified CS to generate an injectable polymer that can form covalent bonds with tissue upon contact. However, the presence of the reactive aldehyde groups can compromise the viability of encapsulated cells. Thus, liposomes were encapsulated in the blend, designed to deliver the ECM derivative, gelatin, after the polymer has adhered to tissue and reached physiological temperature. This work is based on the hypothesis that the discharge of gelatin will enhance the biocompatibility of the material by covalently reacting with, or "end-capping", the aldehyde functionalities within the gel that did not participate in bonding with tissue upon contact. As a comparison, formulations were also created without CS aldehyde and with an alternative adhesion mediator, mucoadhesive calcium alginate particles. Gels formed from blends of PNIPAAm-g-CS and CS aldehyde exhibited increased adhesive strength compared to PNIPAAm-g-CS alone (p<0.05). However, the addition of gelatin-loaded liposomes to the blend significantly decreased the adhesive strength (p<0.05). The encapsulation of alginate microparticles within PNIPAAm-g-CS gels caused the tensile strength to increase twofold over that of PNIPAAm-g-CS blends with CS aldehyde (p<0.05). Cytocompatibility studies indicate that formulations containing alginate particles exhibit reduced cytotoxicity over those containing CS aldehyde. Overall, the results indicated that the adhesives composed of alginate microparticles encapsulated in PNIPAAm-g-CS have the potential to serve as a scaffold for IVD regeneration. PMID:25641647

  1. Developing multi-cellular tumor spheroid model (MCTS) in the chitosan/collagen/alginate (CCA) fibrous scaffold for anticancer drug screening.

    PubMed

    Wang, Jian-Zheng; Zhu, Yu-Xia; Ma, Hui-Chao; Chen, Si-Nan; Chao, Ji-Ye; Ruan, Wen-Ding; Wang, Duo; Du, Feng-Guang; Meng, Yue-Zhong

    2016-05-01

    In this work, a 3D MCTS-CCA system was constructed by culturing multi-cellular tumor spheroid (MCTS) in the chitosan/collagen/alginate (CCA) fibrous scaffold for anticancer drug screening. The CCA scaffolds were fabricated by spray-spinning. The interactions between the components of the spray-spun fibers were evidenced by methods of Coomassie Blue stain, X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FTIR). Co-culture indicated that MCF-7 cells showed a spatial growth pattern of multi-cellular tumor spheroid (MCTS) in the CCA fibrous scaffold with increased proliferation rate and drug-resistance to MMC, ADM and 5-Aza comparing with the 2D culture cells. Significant increases of total viable cells were found in 3D MCTS groups after drug administration by method of apoptotic analysis. Glucose-lactate analysis indicated that the metabolism of MCTS in CCA scaffold was closer to the tumor issue in vivo than the monolayer cells. In addition, MCTS showed the characteristic of epithelial mesenchymal transition (EMT) which is subverted by carcinoma cells to facilitate metastatic spread. These results demonstrated that MCTS in CCA scaffold possessed a more conservative phenotype of tumor than monolayer cells, and anticancer drug screening in 3D MCTS-CCA system might be superior to the 2D culture system. PMID:26952417

  2. Poly-L-lactide/sodium alginate/chitosan microsphere hybrid scaffolds made with braiding manufacture and adhesion technique: Solution to the incongruence between porosity and compressive strength.

    PubMed

    Lin, Jia-Horng; Chen, Chih-Kuang; Wen, Shih-Peng; Lou, Ching-Wen

    2015-01-01

    Bone scaffolds require a three-dimensional structure, high porosity, interconnected pores, adequate mechanical strengths, and non-toxicity. A high porosity is incongruent with mechanical strengths. Therefore, this study combines a braiding method and microsphere solution to create bone scaffolds with a high porosity and sufficient mechanical strengths. First, poly-L-lactide (PLLA) plied yarns are braided into 5-, 10-, 15-, 20-, and 25-layer hollow braids, and then thermally treated at 165 °C for various durations. Next, sodium alginate (SA) microspheres, cross-linked with CaCl2 solution with various concentrations, are combined with PLLA porous braided bone scaffolds to form PLLA/SA/CS microsphere hybrid scaffolds, which are then observed for surface observation, and tested for porosity, water contact angle, compressive strength, MTT assay, bioactivity, alkaline phosphatase (ALP) assay, cell attachment, and statistical analyses. The test results show that the layer amount of the bone scaffold is proportional to the compressive strength. With the same number of layers, the compressive strength is inversely proportional to the concentration of the CaCl2 solution. The results of surface observation, porosity, and water contact angle tests show that PLLA/SA/CS microsphere hybrid scaffolds possess a high porosity and good hydrophilicity; as a result, the braiding manufacture and the bonding technique effectively solve the confliction between porosity and mechanical strength. The concentration of CaCl2 does not pertain to cell activity and ALP results, exemplified by good cell attachment on bone scaffolds for each specification. PMID:25953547

  3. Hybrid Polycaprolactone/Alginate Scaffolds Functionalized with VEGF to Promote de Novo Vessel Formation for the Transplantation of Islets of Langerhans.

    PubMed

    Marchioli, Giulia; Luca, Andrea Di; de Koning, Eelco; Engelse, Marten; Van Blitterswijk, Clemens A; Karperien, Marcel; Van Apeldoorn, Aart A; Moroni, Lorenzo

    2016-07-01

    Although regarded as a promising treatment for type 1 diabetes, clinical islet transplantation in the portal vein is still hindered by a low transplantation outcome. Alternative transplantation sites have been proposed, but the survival of extra-hepatically transplanted islets of Langerhans critically depends on quick revascularization after engraftment. This study aims at developing a new 3D scaffold platform that can actively boost vascularization and may find an application for extra-hepatic islet transplantation. The construct consists of a 3D ring-shaped polycaprolactone (PCL) scaffold with heparinized surface to electrostatically bind vascular endothelial growth factor (VEGF), surrounding a hydrogel core for islets encapsulation. Heparin immobilization improves the amount of VEGF retained by the construct, up to 3.6 fold, compared to untreated PCL scaffolds. In a chicken chorioallanthoic membrane model, VEGF immobilized on the construct enhances angiogenesis in close proximity and on the surface of the scaffolds. After 7 days, islets encapsulated in the alginate core show functional response to glucose stimuli comparable to free-floating islets. Thus, the developed platform has the potential to support rapid vascularization and islet endocrine function. PMID:27113576

  4. Integration of a Novel Injectable Nano Calcium Sulfate/Alginate Scaffold and BMP2 Gene-Modified Mesenchymal Stem Cells for Bone Regeneration

    PubMed Central

    He, Xiaoning; Dziak, Rosemary; Mao, Keya; Genco, Robert; Swithart, Mark; Li, Chunyi

    2013-01-01

    The repair of craniofacial bone defects is surgically challenging due to the complex anatomical structure of the craniofacial skeleton. Current strategies for bone tissue engineering using a preformed scaffold have not resulted in the expected clinical regeneration due to difficulty in seeding cells into the deep internal space of scaffold, and the inability to inject them in minimally invasive surgeries. In this study, we used the osteoconductive and mechanical properties of nano-scale calcium sulfate (nCS) and the biocompatibility of alginate to develop the injectable nCS/alginate (nCS/A) paste, and characterized the effect of this nCS/A paste loaded with bone morphogenetic protein 2 (BMP2) gene-modified rat mesenchymal stem cells (MSCs) on bone and blood vessel growth. Our results showed that the nCS/A paste was injectable under small injection forces. The mechanical properties of the nCS/A paste were increased with an increased proportion of alginate. MSCs maintained their viability after the injection, and MSCs and BMP2 gene-modified MSCs in the injectable pastes remained viable, osteodifferentiated, and yielded high alkaline phosphatase activity. By testing the ability of this injectable paste and BMP2-gene-modified MSCs for the repair of critical-sized calvarial bone defects in a rat model, we found that BMP2-gene-modified MSCs in nCS/A (nCS/A+M/B2) showed robust osteogenic activity, which resulted in consistent bone bridging of the bone defects. The vessel density in nCS/A+M/B2 was significantly higher than that in the groups of blank control, nCS/A alone, and nCS/A mixed with MSCs (nCS/A+M). These results indicate that BMP2 promotes MSCs-mediated bone formation and vascularization in nCS/A paste. Overall, the results demonstrated that the combination of injectable nCS/A paste and BMP2-gene-modified MSCs is a new and effective strategy for the repair of bone defects. PMID:22994418

  5. Synthesis of composite gelatin-hyaluronic acid-alginate porous scaffold and evaluation for in vitro stem cell growth and in vivo tissue integration.

    PubMed

    Singh, Deepti; Tripathi, Anuj; Zo, Sunmi; Singh, Dolly; Han, Sung Soo

    2014-04-01

    Engineering three-dimensional (3-D) porous scaffolds with precise bio-functional properties is one of the most important issues in tissue engineering. In the present study, a three-dimensional gelatin-hyaluronic acid-alginate (GHA) polymeric composite was synthesized by freeze-drying, which was followed by ionic crosslinking using CaCl2, and evaluated for its suitability in bone tissue engineering applications. The obtained matrix showed high porosity (85%), an interconnected pore morphology and a rapid swelling behavior. The rheological analysis of GHA showed a viscoelastic characteristic, which suggested a high load bearing capacity without fractural deformation. The influence of the GHA matrix on cell growth and on modulating the differentiation ability of mesenchymal stem cells was evaluated by different biochemical and immunostaining assays. The monitoring of cells over a period of four weeks showed increased cellular proliferation and osteogenic differentiation without external growth factors, compared with control (supplemented with osteogenic differentiation medium). The in vivo matrix implantation showed higher matrix-tissue integration and cell infiltration as the duration of the implant increased. These results suggest that a porous GHA matrix with suitable mechanical integrity and tissue compatibility is a promising substrate for the osteogenic differentiation of stem cells for bone tissue engineering applications. PMID:24572494

  6. Novel alginate-based nanocarriers as a strategy to include high concentrations of hydrophobic compounds in hydrogels for topical application

    NASA Astrophysics Data System (ADS)

    Nguyen, H. T. P.; Munnier, E.; Souce, M.; Perse, X.; David, S.; Bonnier, F.; Vial, F.; Yvergnaux, F.; Perrier, T.; Cohen-Jonathan, S.; Chourpa, I.

    2015-06-01

    The cutaneous penetration of hydrophobic active molecules is of foremost concern in the dermatology and cosmetic formulation fields. The poor solubility in water of those molecules limits their use in hydrophilic forms such as gels, which are favored by patients with chronic skin disease. The aim of this work is to design a novel nanocarrier of hydrophobic active molecules and to determine its potential as an ingredient of a topical form. The nanocarrier consists of an oily core surrounded by a protective shell of alginate, a natural polysaccharide isolated from brown algae. These calcium alginate-based nanocarriers (CaANCs) were prepared at room temperature and without the use of organic solvent by an accelerated nanoemulsification-polymer crosslinking method. The size (hydrodynamic diameter ˜200 nm) and surface charge (zeta potential ˜ - 30 mV) of the CaANCs are both compatible with their application on skin. CaANCs loaded with a fluorescent label were stable in model hydrophilic galenic forms under different storage conditions. Curcumin was encapsulated in CaANCs with an efficiency of ˜95%, fully retaining its antioxidant activity. The application of the curcumin-loaded CaANCs on excised human skin led to a significant accumulation of the active molecules in the upper layers of the skin, asserting the potential of these nanocarriers in active pharmaceutical and cosmetic ingredients topical delivery.

  7. Incorporation of magnesium ions into photo-crosslinked alginate hydrogel enhanced cell adhesion ability.

    PubMed

    Yin, Miao; Xu, Fei; Ding, Huifen; Tan, Fei; Song, Fangfang; Wang, Jiawei

    2015-09-01

    Photo-crosslinked alginate hydrogel attracts wide interest in tissue engineering because of its excellent controllability and stability. However, its highly hydrophilic property makes cell adhesion difficult. Plenty of studies have confirmed that magnesium ions (Mg(2+) ) can efficiently improve the attachment of osteoblasts. In this study, for the first time, we fabricated a durable, crosslinked, alginate hydrogel with a dual-crosslinking network. Photo-crosslinked alginate hydrogel was chosen as the basic backbone, and various amounts of Mg(2+) were incorporated into the hydrogel through ionic crosslinking. The results showed that the physicochemical properties of the hydrogels, including surface structure, composition, swelling ratio, ion release and elastic modulus, could be well tuned by controlling the amount of Mg(2+) incorporated. In addition, a certain amount of Mg(2+) significantly improved the attachment and spread of osteoblasts on the hydrogels. These characteristics make Mg(2+) -incorporated photo-crosslinked alginate hydrogel a promising scaffold for bone tissue engineering. PMID:25694165

  8. 3D Cell Culture in Alginate Hydrogels

    PubMed Central

    Andersen, Therese; Auk-Emblem, Pia; Dornish, Michael

    2015-01-01

    This review compiles information regarding the use of alginate, and in particular alginate hydrogels, in culturing cells in 3D. Knowledge of alginate chemical structure and functionality are shown to be important parameters in design of alginate-based matrices for cell culture. Gel elasticity as well as hydrogel stability can be impacted by the type of alginate used, its concentration, the choice of gelation technique (ionic or covalent), and divalent cation chosen as the gel inducing ion. The use of peptide-coupled alginate can control cell–matrix interactions. Gelation of alginate with concomitant immobilization of cells can take various forms. Droplets or beads have been utilized since the 1980s for immobilizing cells. Newer matrices such as macroporous scaffolds are now entering the 3D cell culture product market. Finally, delayed gelling, injectable, alginate systems show utility in the translation of in vitro cell culture to in vivo tissue engineering applications. Alginate has a history and a future in 3D cell culture. Historically, cells were encapsulated in alginate droplets cross-linked with calcium for the development of artificial organs. Now, several commercial products based on alginate are being used as 3D cell culture systems that also demonstrate the possibility of replacing or regenerating tissue. PMID:27600217

  9. Boron nitride nanotubes included thermally cross-linked gelatin-glucose scaffolds show improved properties.

    PubMed

    Şen, Özlem; Culha, Mustafa

    2016-02-01

    Boron nitride nanotubes (BNNTs) are increasingly investigated for their medical and biomedical applications due to their unique properties such as resistance to oxidation, thermal and electrical insulation, and biocompatibility. BNNTs can be used to enhance mechanical strength of biomedical structures such as scaffolds in tissue engineering applications. In this study, we report the use of BNNTs and hydroxylated BNNTs (BNNT-OH) to improve the properties of gelatin-glucose scaffolds prepared with electrospinning technique. Human dermal fibroblast (HDF) cells are used for the toxicity assessment and cell seeding studies. It is found that the addition of BNNTs into the scaffold does not influence cell viability, decreases the scaffold degradation rate, and improves cell attachment and proliferation compared to only-gelatin scaffold. PMID:26642075

  10. Understanding Alginate Gel Development for Bioclogging and Biogeophysical Experiments

    NASA Astrophysics Data System (ADS)

    Brown, I.; Atekwana, E. A.; Abdel Aal, G. Z.; Atekwana, E. A.; Sarkisova, S.; Patrauchan, M.

    2012-12-01

    Bioremediation strategies to mitigate the transport of heavy metals and radionuclides in subsurface sediments have largely targeted to increase the mobility and/or solubility of these compounds by the stimulation of biogeochemical activity of the metal- and sulfate-reducing bacteria. The latter secrete and/or release out diverse biochemical molecule including, first of all, organic acids and biopolymers such as alginic acid, proteins and DNA. Alginate gel is one of the major components determining the structure of biofilm which causes clogging in porous media. Biopolymers composing biofilm having, at least, two main functions: to be a scaffold for a microbial biofilm, and to regulate the exchange of metabolites and ions between an environment and bacterial cells. Additionally, the accumulation of biopolymers and a matured biofilm within porous media was shown to contribute to a detectable biogeophysical signal, spectral induced polarization (SIP), in particular. Our objective is to understand the role of different biofilm components on the SIP response as the latter has been proposed as a non-invasive tool to monitor biofilm development and rate of clogging in the subsurface. Understanding the process of alginate gel development may aid in the understanding of the fate and transport of mineralized heavy metals and radionuclides in contaminated soils. Here we describe the reciprocal relationship between environmental chemistry and alginate gel development. Commercial (Sigma) alginic acid (AA) was used as a substratum for the preparation of a model gel. AA was solubilized by adjusting solutions with pH up to 4 with 0.1 NaOH. Both Ca(OH)2 or CaCl2 were used to initiate the gelation of alginate. pH, fluid conductivity, soluble Ca2+ concentration, and a yield of gelated alginate were monitored in both liquid and porous media after the interaction of calcium compounds with alginate. This study confirms the critical role of Ca2+ for alginate gelation, biofilm development

  11. Jellyfish collagen and alginate: Combined marine materials for superior chondrogenesis of hMSC.

    PubMed

    Pustlauk, W; Paul, B; Gelinsky, M; Bernhardt, A

    2016-07-01

    Marine, hybrid constructs of porous scaffolds from fibrillized jellyfish collagen and alginate hydrogel are mimicking both of the main tissue components of cartilage, thus being a promising approach for chondrogenic differentiation of human mesenchymal stem cells (hMSC). Investigating their potential for articular cartilage repair, the present study examined scaffolds being either infiltrated with an alginate-cell-suspension (ACS) or seeded with hMSC and embedded in alginate after cell adhesion (EAS). Hybrid constructs with 2×10(5) and 4.5×10(5)hMSC/scaffold were compared to hMSC encapsulated in pure alginate discs, both chondrogenically stimulated for 21days. Typical round, chondrocyte-like morphology was observed in pure alginate gels and ACS scaffolds, while cells in EAS were elongated and tightly attached to the collagen pores. Col 2 gene expression was comparable in all scaffold types examined. However, the Col 2/Col 1 ratio was higher for pure alginate discs and ACS scaffolds compared to EAS. In contrast, cells in EAS scaffolds displayed higher gene expression of Sox 9, Col 11 and ACAN compared to ACS and pure alginate. Secretion of sulfated glycosaminoglycans (sGAG) was comparable for ACS and EAS scaffolds. In conclusion hybrid constructs of jellyfish collagen and alginate support hMSC chondrogenic differentiation and provide more stable and constructs compared to pure hydrogels. PMID:27127044

  12. Alginate: properties and biomedical applications

    PubMed Central

    Lee, Kuen Yong; Mooney, David J.

    2011-01-01

    Alginate is a biomaterial that has found numerous applications in biomedical science and engineering due to its favorable properties, including biocompatibility and ease of gelation. Alginate hydrogels have been particularly attractive in wound healing, drug delivery, and tissue engineering applications to date, as these gels retain structural similarity to the extracellular matrices in tissues and can be manipulated to play several critical roles. This review will provide a comprehensive overview of general properties of alginate and its hydrogels, their biomedical applications, and suggest new perspectives for future studies with these polymers. PMID:22125349

  13. Development of a morphogenetically active scaffold for three-dimensional growth of bone cells: biosilica-alginate hydrogel for SaOS-2 cell cultivation.

    PubMed

    Müller, Werner E G; Schröder, Heinz C; Feng, Qingling; Schlossmacher, Ute; Link, Thorben; Wang, Xiaohong

    2015-11-01

    Polymeric silica is formed from ortho-silicate during a sol-gel formation process, while biosilica is the product of an enzymatically driven bio-polycondensation reaction. Both polymers have recently been described as a template that induces an increased expression of the genes encoding bone morphogenetic protein 2 (BMP-2) and osteoprotegerin in osteoblast-related SaOS-2 cells; simultaneously or subsequently the cells respond with enhanced hydroxyapatite formation. In order to assess whether the biocompatible polymeric silica/biosilica can serve as a morphogenetically active matrix suitable for three-dimensional (3D) cell growth, or even for 3D cell bioprinting, SaOS-2 cells were embedded into a Na-alginate-based hydrogel. Four different gelatinous hydrogel matrices were used for suspending SaOS-2 cells: (a) the hydrogel alone; (b) the hydrogel with 400 μM ortho-silicate; (c) the hydrogel supplemented with 400 μM ortho-silicate and recombinant silicatein to allow biosilica synthesis to occur; and (d) the hydrogel with ortho-silicate and BSA. The SaOS-2 cells showed an increased growth if silica/biosilica components were present in the hydrogel. Likewise intensified was the formation of hydroxyapatite nodules in the silica-containing hydrogels. After an incubation period of 2 weeks, cells present in silica-containing hydrogels showed a significantly higher expression of the genes encoding the cytokine BMP-2, the major fibrillar structural protein collagen 1 and likewise of carbonic anhydrase. It is concluded that silica, and to a larger extent biosilica, retains its morphogenetic/osteogenic potential after addition to Na-alginate-based hydrogels. This property might qualify silica hydrogels to be also used as a matrix for 3D cell printing. PMID:23585362

  14. [Alginates in therapy for gastroesophageal reflux disease].

    PubMed

    Avdeev, V G

    2015-01-01

    This article presents evidence of the prevalence of gastroesophageal reflux disease (GERD) and highlights its main treatment options. Among its medications, particular emphasis is laid on alginates and their main mechanisms of action are described. There is information on the efficacy of alginates, including the alginate-antacid Gaviscon Double Action, in treating GERD. Recommendations for how to administer these drugs are given. PMID:26155630

  15. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies

    PubMed Central

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M.

    2016-01-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca2+ ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering. PMID:27578567

  16. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies.

    PubMed

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M

    2016-01-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca(2+) ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering. PMID:27578567

  17. Preparation and characterization of hydroxyapatite/sodium alginate biocomposites for bone implant application

    NASA Astrophysics Data System (ADS)

    Kanasan, Nanthini; Adzila, Sharifah; Suid, Mohd Syafiq; Gurubaran, P.

    2016-07-01

    In biomedical fields, synthetic scaffolds are being improved by using the ceramics, polymers and composites materials to avoid the limitations of allograft. Ceramic-polymer composites are appearing to be the most successful bone graft substitute in human body. The natural bones itself are well-known as composite of collagen and hydroxyapatite. In this research, precipitation method was used to synthesis hydroxyapatite (HA)/sodium alginate (SA) in various parameters. This paper describes the hydroxyapatite/sodium alginate biocomposite which suitable for use in bone defects or regeneration of bone through the characterizations which include FTIR, FESEM, EDS and DTA. In FTIR, the characteristi peaks of PO4-3 and OH- groups which corresponding to hydroxyapatite are existed in the mixing powders. The needle-size particle of hydroxyapatite/ alginate (HA/SA) are observed in FESEM in the range of 15.8nm-38.2nm.EDS confirmed the existence of HA/SA composition in the mixing powders. There is an endothermic peak which corresponds to the dehydration and the loss of physically adsorbed water molecules of the hydroxyapatite (HA)/sodium alginate (SA) powder which are described in DTA.

  18. Chitosan-Alginate Biocomposite Containing Fucoidan for Bone Tissue Engineering

    PubMed Central

    Venkatesan, Jayachandran; Bhatnagar, Ira; Kim, Se-Kwon

    2014-01-01

    Over the last few years, significant research has been conducted in the construction of artificial bone scaffolds. In the present study, different types of polymer scaffolds, such as chitosan-alginate (Chi-Alg) and chitosan-alginate with fucoidan (Chi-Alg-fucoidan), were developed by a freeze-drying method, and each was characterized as a bone graft substitute. The porosity, water uptake and retention ability of the prepared scaffolds showed similar efficacy. The pore size of the Chi-Alg and Chi-Alg-fucoidan scaffolds were measured from scanning electron microscopy and found to be 62–490 and 56–437 µm, respectively. In vitro studies using the MG-63 cell line revealed profound cytocompatibility, increased cell proliferation and enhanced alkaline phosphatase secretion in the Chi-Alg-fucoidan scaffold compared to the Chi-Alg scaffold. Further, protein adsorption and mineralization were about two times greater in the Chi-Alg-fucoidan scaffold than the Chi-Alg scaffold. Hence, we suggest that Chi-Alg-fucoidan will be a promising biomaterial for bone tissue regeneration. PMID:24441614

  19. Development of a porous PLGA-based scaffold for mastoid air cell regeneration

    PubMed Central

    Gould, Toby W. A.; Birchall, John P.; Mallick, Ali S.; Alliston, Tamara; Lustig, Lawrence R.; Shakesheff, Kevin M.

    2015-01-01

    Objective To develop a porous, biodegradable scaffold for mastoid air cell regeneration. Study Design In vitro development of a temperature-sensitive poly(DL-lactic acid-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) scaffold tailored for this application. Methods Human mastoid bone microstructure and porosity was investigated using micro-computed tomography. PLGA/PEG-alginate scaffolds were developed and scaffold porosity was assessed. Human bone marrow mesenchymal stem cells (hBM-MSCs) were cultured on the scaffolds in vitro. Scaffolds were loaded with ciprofloxacin and release of ciprofloxacin over time in vitro was assessed. Results Porosity of human mastoid bone was measured at 83% with an average pore size of 1.3mm. PLGA/PEG-alginate scaffold porosity ranged from 43–78% depending on the alginate bead content. hBM-MSCs proliferate on the scaffolds in vitro, and release of ciprofloxacin from the scaffolds was demonstrated over 7–10 weeks. Conclusion The PLGA/PEG-alginate scaffolds developed in this study demonstrate similar structural features to human mastoid bone, support cell growth and display sustained antibiotic release. These scaffolds may be of potential clinical use in mastoid air cell regeneration. Further in vivo studies to assess the suitability of PLGA/PEG-alginate scaffolds for this application are required. PMID:23670365

  20. Influence of mechanical properties of alginate-based substrates on the performance of Schwann cells in culture.

    PubMed

    Ning, Liqun; Xu, Yitong; Chen, Xiongbiao; Schreyer, David J

    2016-06-01

    In tissue engineering, artificial tissue scaffolds containing living cells have been studied for tissue repair and regeneration. Notably, the performance of these encapsulated-in-scaffolds cells in terms of cell viability, proliferation, and expression of function during and after the scaffold fabrication process, has not been well documented because of the influence of mechanical, chemical, and physical properties of the scaffold substrate materials. This paper presents our study on the influence of mechanical properties of alginate-based substrates on the performance of Schwann cells, which are the major glial cells of peripheral nervous system. Given the fact that alginate polysaccharide hydrogel has poor cell adhesion properties, in this study, we examined several types of cell-adhesion supplements and found that alginate covalently modified with RGD peptide provided improved cell proliferation and adhesion. We prepared alginate-based substrates for cell culture using varying alginate concentrations for altering their mechanical properties, which were confirmed by compression testing. Then, we examined the viability, proliferation, morphology, and expression of the extracellular matrix protein laminin of Schwann cells that were seeded on the surface of alginate-based substrates (or 2D culture) or encapsulated within alginate-based substrates (3D cultures), and correlated the examined cell performance to the alginate concentration (or mechanical properties) of hydrogel substrates. Our findings suggest that covalent attachment of RGD peptide can improve the success of Schwann cell encapsulation within alginate-based scaffolds, and provide guidance for regulating the mechanical properties of alginate-based scaffolds containing Schwann cells for applications in peripheral nervous system regeneration and repair. PMID:27012482

  1. Alginate composites for bone tissue engineering: a review.

    PubMed

    Venkatesan, Jayachandran; Bhatnagar, Ira; Manivasagan, Panchanathan; Kang, Kyong-Hwa; Kim, Se-Kwon

    2015-01-01

    Bone is a complex and hierarchical tissue consisting of nano hydroxyapatite and collagen as major portion. Several attempts have been made to prepare the artificial bone so as to replace the autograft and allograft treatment. Tissue engineering is a promising approach to solve the several issues and is also useful in the construction of artificial bone with materials including polymer, ceramics, metals, cells and growth factors. Composites consisting of polymer-ceramics, best mimic the natural functions of bone. Alginate, an anionic polymer owing enormous biomedical applications, is gaining importance particularly in bone tissue engineering due to its biocompatibility and gel forming properties. Several composites such as alginate-polymer (PLGA, PEG and chitosan), alginate-protein (collagen and gelatin), alginate-ceramic, alginate-bioglass, alginate-biosilica, alginate-bone morphogenetic protein-2 and RGD peptides composite have been investigated till date. These alginate composites show enhanced biochemical significance in terms of porosity, mechanical strength, cell adhesion, biocompatibility, cell proliferation, alkaline phosphatase increase, excellent mineralization and osteogenic differentiation. Hence, alginate based composite biomaterials will be promising for bone tissue regeneration. This review will provide a broad overview of alginate preparation and its applications towards bone tissue engineering. PMID:25020082

  2. Stability of alginate-immobilized algal cells

    SciTech Connect

    Dainty, A.L.; Goulding, K.H.; Robinson, P.K.; Simpkins, I; Trevan, M.D.

    1986-01-01

    Investigations were carried out using immobilized Chlorella cells to determine the diameter, compressibility, tolerance to phosphate chelation, and ability to retain algal cells during incubation of various alginate beads. These physical bead-characteristics were affected by a variety of interactive factors, including multivalent cation type (hardening agent) and cell, cation, and alginate concentration, the latter exhibiting a predominant influence. The susceptibility of alginate beads to phosphate chelation involved a complex interaction of cation type, concentration, and pH of phosphate solution. A scale of response ranging from gel swelling to gel shrinking was observed for a range of conditions. However, stable Ca alginate beads were maintained in incubation media with a pH of 5.5 and a phosphate concentration of 5 micro M. A preliminary investigation into cell leakage from the beads illustrated the importance of maintaining a stable gel structure and limiting cell growth to reduce leakage.

  3. Diffusivity of Cu2+ in calcium alginate gel beads: recalculation.

    PubMed

    Lewandowski, Z; Roe, F

    1994-01-20

    Calculations of the diffusivity of Cu(2+) in calcium alginate gel beads using the shrinking core model were checked by us. Corrected results are reported here. Diffusivity was still found to increase with increasing alginate concentration, but at a lower rate than reported in the cited paper. The diffusivity increased by a factor of 2 over the range of alginate concentrations studied rather than 10. The original data is included with sample calculations. PMID:18615614

  4. Stability of alginate microbead properties in vitro

    PubMed Central

    Moya, Monica L.; Morley, Michael; Khanna, Omaditya; Opara, Emmanuel C.

    2013-01-01

    Alginate microbeads have been investigated clinically for a number of therapeutic interventions, including drug delivery for treatment of ischemic tissues, cell delivery for tissue regeneration, and islet encapsulation as a therapy for type I diabetes. The physical properties of the microbeads play an important role in regulating cell behavior, protein release, and biological response following implantation. In this research alginate microbeads were synthesized, varying composition (mannuronic acid to guluronic acid ratio), concentration of alginate and needle gauge size. Following synthesis, the size, volume fraction, and morphometry of the beads were quantified. In addition, these properties were monitored over time in vitro in the presence of varying calcium levels in the microenvironment. The initial volume available for solute diffusion increased with alginate concentration and mannuronic (M) acid content, and bead diameter decreased with M content but increased with needle diameter. Interestingly, microbeads eroded completely in saline in less than 3 weeks regardless of synthesis conditions much faster than what has been observed in vivo. However, microbead stability was increased by the addition of calcium in the culture medium. Beads synthesized with low alginate concentration and high G content exhibited a more rapid change in physical properties even in the presence of calcium. These data suggest that temporal variations in the physical characteristics of alginate microbeads can occur in vitro depending on synthesis conditions and microbead environment. The results presented here will assist in optimizing the design of the materials for clinical application in drug delivery and cell therapy. PMID:22350778

  5. Magneto-responsive alginate capsules

    NASA Astrophysics Data System (ADS)

    Degen, Patrick; Zwar, Elena; Schulz, Imke; Rehage, Heinz

    2015-05-01

    Upon incorporation of magnetic nanoparticles (mNPs) into gels, composite materials called ferrogels are obtained. These magneto-responsive systems have a wide range of potential applications including switches and sensors as well as drug delivery systems. In this article, we focus on the properties of calcium alginate capsules, which are widely used as carrier systems in medicine and technology. We studied the incorporation of different kinds of mNPs in matrix capsules and in the core and the shell of hollow particles. We found out that not all particle-alginate or particle-CaCl2 solution combinations were suitable for a successful capsule preparation on grounds of a destabilization of the nanoparticles or the polymer. For those systems allowing the preparation of switchable beads or capsules, we systematically studied the size and microscopic structure of the capsules, their magnetic behavior and mechanical resistance.

  6. Novel crosslinked alginate/hyaluronic acid hydrogels for nerve tissue engineering

    NASA Astrophysics Data System (ADS)

    Wang, Min-Dan; Zhai, Peng; Schreyer, David J.; Zheng, Ruo-Shi; Sun, Xiao-Dan; Cui, Fu-Zhai; Chen, Xiong-Biao

    2013-09-01

    Artificial tissue engineering scaffolds can potentially provide support and guidance for the regrowth of severed axons following nerve injury. In this study, a hybrid biomaterial composed of alginate and hyaluronic acid (HA) was synthesized and characterized in terms of its suitability for covalent modification, biocompatibility for living Schwann cells and feasibility to construct three dimensional (3D) scaffolds. Carbodiimide mediated amide formation for the purpose of covalent crosslinking of the HA was carried out in the presence of calciumions that ionically crosslink alginate. Amide formation was found to be dependent on the concentrations of carbodiimide and calcium chloride. The double-crosslinked composite hydrogels display biocompatibility that is comparable to simple HA hydrogels, allowing for Schwann cell survival and growth. No significant difference was found between composite hydrogels made from different ratios of alginate and HA. A 3D BioPlotter™ rapid prototyping system was used to fabricate 3D scaffolds. The result indicated that combining HA with alginate facilitated the fabrication process and that 3D scaffolds with porous inner structure can be fabricated from the composite hydrogels, but not from HA alone. This information provides a basis for continuing in vitro and in vivo tests of the suitability of alginate/HA hydrogel as a biomaterial to create living cell scaffolds to support nerve regeneration.

  7. Automated quantitative assessment of three-dimensional bioprinted hydrogel scaffolds using optical coherence tomography

    PubMed Central

    Wang, Ling; Xu, Mingen; Zhang, LieLie; Zhou, QingQing; Luo, Li

    2016-01-01

    Reconstructing and quantitatively assessing the internal architecture of opaque three-dimensional (3D) bioprinted hydrogel scaffolds is difficult but vital to the improvement of 3D bioprinting techniques and to the fabrication of functional engineered tissues. In this study, swept-source optical coherence tomography was applied to acquire high-resolution images of hydrogel scaffolds. Novel 3D gelatin/alginate hydrogel scaffolds with six different representative architectures were fabricated using our 3D bioprinting system. Both the scaffold material networks and the interconnected flow channel networks were reconstructed through volume rendering and binarisation processing to provide a 3D volumetric view. An image analysis algorithm was developed based on the automatic selection of the spatially-isolated region-of–interest. Via this algorithm, the spatially-resolved morphological parameters including pore size, pore shape, strut size, surface area, porosity, and interconnectivity were quantified precisely. Fabrication defects and differences between the designed and as-produced scaffolds were clearly identified in both 2D and 3D; the locations and dimensions of each of the fabrication defects were also defined. It concludes that this method will be a key tool for non-destructive and quantitative characterization, design optimisation and fabrication refinement of 3D bioprinted hydrogel scaffolds. Furthermore, this method enables investigation into the quantitative relationship between scaffold structure and biological outcome. PMID:27231597

  8. Automated quantitative assessment of three-dimensional bioprinted hydrogel scaffolds using optical coherence tomography.

    PubMed

    Wang, Ling; Xu, Mingen; Zhang, LieLie; Zhou, QingQing; Luo, Li

    2016-03-01

    Reconstructing and quantitatively assessing the internal architecture of opaque three-dimensional (3D) bioprinted hydrogel scaffolds is difficult but vital to the improvement of 3D bioprinting techniques and to the fabrication of functional engineered tissues. In this study, swept-source optical coherence tomography was applied to acquire high-resolution images of hydrogel scaffolds. Novel 3D gelatin/alginate hydrogel scaffolds with six different representative architectures were fabricated using our 3D bioprinting system. Both the scaffold material networks and the interconnected flow channel networks were reconstructed through volume rendering and binarisation processing to provide a 3D volumetric view. An image analysis algorithm was developed based on the automatic selection of the spatially-isolated region-of-interest. Via this algorithm, the spatially-resolved morphological parameters including pore size, pore shape, strut size, surface area, porosity, and interconnectivity were quantified precisely. Fabrication defects and differences between the designed and as-produced scaffolds were clearly identified in both 2D and 3D; the locations and dimensions of each of the fabrication defects were also defined. It concludes that this method will be a key tool for non-destructive and quantitative characterization, design optimisation and fabrication refinement of 3D bioprinted hydrogel scaffolds. Furthermore, this method enables investigation into the quantitative relationship between scaffold structure and biological outcome. PMID:27231597

  9. ERK Signals: Scaffolding Scaffolds?

    PubMed Central

    Casar, Berta; Crespo, Piero

    2016-01-01

    ERK1/2 MAP Kinases become activated in response to multiple intra- and extra-cellular stimuli through a signaling module composed of sequential tiers of cytoplasmic kinases. Scaffold proteins regulate ERK signals by connecting the different components of the module into a multi-enzymatic complex by which signal amplitude and duration are fine-tuned, and also provide signal fidelity by isolating this complex from external interferences. In addition, scaffold proteins play a central role as spatial regulators of ERKs signals. In this respect, depending on the subcellular localization from which the activating signals emanate, defined scaffolds specify which substrates are amenable to be phosphorylated. Recent evidence has unveiled direct interactions among different scaffold protein species. These scaffold-scaffold macro-complexes could constitute an additional level of regulation for ERK signals and may serve as nodes for the integration of incoming signals and the subsequent diversification of the outgoing signals with respect to substrate engagement. PMID:27303664

  10. Gingival Mesenchymal Stem Cell (GMSC) Delivery System Based on RGD-Coupled Alginate Hydrogel with Antimicrobial Properties: A Novel Treatment Modality for Peri-Implantitis

    PubMed Central

    Diniz, Ivana M. A.; Chen, Chider; Ansari, Sahar; Zadeh, Homayoun H.; Moshaverinia, Maryam; Chee, Daniel; Marques, Márcia M.; Shi, Songtao; Moshaverinia, Alireza

    2015-01-01

    Purpose Peri-implantitis is one of the most common inflammatory complications in dental implantology. Similar to periodontitis, in peri-implantitis, destructive inflammatory changes take place in the tissues surrounding a dental implant. Bacterial flora at the failing implant sites resemble the pathogens in periodontal disease and consist of Gram-negative anaerobic bacteria including Aggregatibacter actinomycetemcomitans (Aa). Here we demonstrate the effectiveness of a silver lactate (SL)-containing RGD-coupled alginate hydrogel scaffold as a promising stem cell delivery vehicle with antimicrobial properties. Materials and Methods Gingival mesenchymal stem cells (GMSCs) or human bone marrow mesenchymal stem cells (hBMMSCs) were encapsulated in SL-loaded alginate hydrogel microspheres. Stem cell viability, proliferation, and osteo-differentiation capacity were analyzed. Results Our results showed that SL exhibited antimicrobial properties against Aa in a dose-dependent manner, with 0.50 mg/ml showing the greatest antimicrobial properties while still maintaining cell viability. At this concentration, SL-containing alginate hydrogel was able to inhibit Aa on the surface of Ti discs and significantly reduce the bacterial load in Aa suspensions. Silver ions were effectively released from the SL-loaded alginate microspheres for up to 2 weeks. Osteogenic differentiation of GMSCs and hBMMSCs encapsulated in the SL-loaded alginate microspheres were confirmed by the intense mineral matrix deposition and high expression of osteogenesis-related genes. Conclusion Taken together, our findings confirm that GMSCs encapsulated in RGD-modified alginate hydrogel containing SL show promise for bone tissue engineering with antimicrobial properties against Aa bacteria in vitro. PMID:26216081

  11. Alginate-polymethacrylate hybrid hydrogels with double ionic and covalent network for tissue engineering

    NASA Astrophysics Data System (ADS)

    Schizzi, I.; Utzeri, R.; Castellano, M.; Stagnaro, P.

    2016-05-01

    Hydrogels based on alginates are very promising candidates to realize scaffolds for tissue engineering. Indeed, alginate hydrogels are able to mimic the extracellular matrix (ECM) thus promoting in vitro and/or in vivo cell growth; moreover, their capability of giving rise to highly porous structures can specifically favor the osteochondral tissue regeneration. However, mechanical properties of polymeric hydrogels are often inadequate to endow the final constructs with the required characteristics of elasticity and toughness. Here alginate/polymethacrylate hybrid hydrogels, with a suitable porous structure and characterized by a double network, ionic (from alginate) and covalent (from polymethacrylate) were designed and realized. The mechanical performance of these hybrid materials resulted, as expected, improved due to the double interconnected network, where the alginate portion provides the appropriate micro-environment mimicking the ECM, whereas the polymethacrylate portion acts as a reinforce.

  12. A prospective comparison of alginate-hydrogel with standard medical therapy to determine impact on functional capacity and clinical outcomes in patients with advanced heart failure (AUGMENT-HF trial)

    PubMed Central

    Anker, Stefan D.; Coats, Andrew J.S.; Cristian, Gabriel; Dragomir, Dinu; Pusineri, Enrico; Piredda, Massimo; Bettari, Luca; Dowling, Robert; Volterrani, Maurizio; Kirwan, Bridget-Anne; Filippatos, Gerasimos; Mas, Jean-Louis; Danchin, Nicolas; Solomon, Scott D.; Lee, Randall J.; Ahmann, Frank; Hinson, Andy; Sabbah, Hani N.; Mann, Douglas L.

    2015-01-01

    Aims AUGMENT-HF was an international, multi-centre, prospective, randomized, controlled trial to evaluate the benefits and safety of a novel method of left ventricular (LV) modification with alginate-hydrogel. Methods Alginate-hydrogel is an inert permanent implant that is directly injected into LV heart muscle and serves as a prosthetic scaffold to modify the shape and size of the dilated LV. Patients with advanced chronic heart failure (HF) were randomized (1 : 1) to alginate-hydrogel (n = 40) in combination with standard medical therapy or standard medical therapy alone (Control, n = 38). The primary endpoint of AUGMENT-HF was the change in peak VO2 from baseline to 6 months. Secondary endpoints included changes in 6-min walk test (6MWT) distance and New York Heart Association (NYHA) functional class, as well as assessments of procedural safety. Results Enrolled patients were 63 ± 10 years old, 74% in NYHA functional class III, had a LV ejection fraction of 26 ± 5% and a mean peak VO2 of 12.2 ± 1.8 mL/kg/min. Thirty-five patients were successfully treated with alginate-hydrogel injections through a limited left thoracotomy approach without device-related complications; the 30-day surgical mortality was 8.6% (3 deaths). Alginate-hydrogel treatment was associated with improved peak VO2 at 6 months—treatment effect vs. Control: +1.24 mL/kg/min (95% confidence interval 0.26–2.23, P = 0.014). Also 6MWT distance and NYHA functional class improved in alginate-hydrogel-treated patients vs. Control (both P < 0.001). Conclusion Alginate-hydrogel in addition to standard medical therapy for patients with advanced chronic HF was more effective than standard medical therapy alone for improving exercise capacity and symptoms. The results of AUGMENT-HF provide proof of concept for a pivotal trial. Trial Registration Number NCT01311791. PMID:26082085

  13. Towards antimicrobial yet bioactive Cu-alginate hydrogels.

    PubMed

    Madzovska-Malagurski, I; Vukasinovic-Sekulic, M; Kostic, D; Levic, S

    2016-01-01

    The simplest approach to enhance alginate hydrogel characteristics and functional properties is to replace the calcium in the process of alginate gelation with other metallic ions which are essential for living systems. Gelling of alginate with other ions and using modern encapsulation techniques can provide new delivery systems with required properties. Hence, in this study Cu-alginate hydrogels in the form of microbeads were produced by electrostatic extrusion using gelling solutions with Cu(II) concentrations in the range 13.5-270 mM and comprehensively characterized in vitro. The variation of gelling solution concentration influenced the microbead Cu(II) content, size, biomechanical properties, Cu(II) release and subsequently potential biomedical application. The formulations chosen for biomedical evaluation showed potential for antimicrobial and tissue engineering applications. Microbeads with higher Cu(II) loading (~100 μmol g(-1)) induced immediate bactericidal effects against Escherichia coli and Staphylococcus aureus. Conversely, Cu(II) release from microbeads with the Cu(II) content of ~60 μmol g(-1) was slower and they were suitable for promoting and maintaining chondrogenic phenotype of bovine calf chondrocytes in 3D culture. Results of this study have shown possibilities for tuning Cu-alginate properties for potential biomedical applications such as antimicrobial wound dressings, tissue engineering scaffolds or articular cartilage implants. PMID:27305176

  14. Wound Dressing Model of Human Umbilical Cord Mesenchymal Stem Cells-Alginates Complex Promotes Skin Wound Healing by Paracrine Signaling

    PubMed Central

    Yang, Huachao; Tang, Zhenrui; Long, Gang; Huang, Wen

    2016-01-01

    Purpose. To probe growth characteristics of human umbilical cord mesenchymal stem cells (hUCMSCs) cultured with alginate gel scaffolds, and to explore feasibility of wound dressing model of hUCMSCs-alginates compound. Methods. hUCMSCs were isolated, cultured, and identified in vitro. Then cells were cultivated in 100 mM calcium alginate gel, and the capacity of proliferation and migration and the expression of vascular endothelial growth factors (VEGF) were investigated regularly. Wound dressing model of hUCMSCs-alginate gel mix was transplanted into Balb/c mice skin defects. Wound healing rate and immunohistochemistry were examined. Results. hUCMSCs grew well but with little migration ability in the alginate gel. Compared with control group, a significantly larger cell number and more VEGF expression were shown in the gel group after culturing for 3–6 days (P < 0.05). In addition, a faster skin wound healing rate with more neovascularization was observed in the hUCMSCs-alginate gel group than in control groups at 15th day after surgery (P < 0.05). Conclusion. hUCMSCs can proliferate well and express massive VEGF in calcium alginate gel porous scaffolds. Wound dressing model of hUCMSCs-alginate gel mix can promote wound healing through paracrine signaling. PMID:26880953

  15. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food... GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Calcium alginate is prepared...

  16. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Potassium alginate...

  17. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium alginate. 184.1724 Section 184.1724 Food and... Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Sodium alginate...

  18. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Sodium alginate is prepared by...

  19. Utilizing Core–Shell Fibrous Collagen-Alginate Hydrogel Cell Delivery System for Bone Tissue Engineering

    PubMed Central

    Perez, Roman A.; Kim, Meeju; Kim, Tae-Hyun; Kim, Joong-Hyun; Lee, Jae Ho; Park, Jeong-Hui; Knowles, Jonathan C.

    2014-01-01

    Three-dimensional matrices that encapsulate and deliver stem cells with defect-tuned formulations are promising for bone tissue engineering. In this study, we designed a novel stem cell delivery system composed of collagen and alginate as the core and shell, respectively. Mesenchymal stem cells (MSCs) were loaded into the collagen solution and then deposited directly into a fibrous structure while simultaneously sheathing with alginate using a newly designed core–shell nozzle. Alginate encapsulation was achieved by the crosslinking within an adjusted calcium-containing solution that effectively preserved the continuous fibrous structure of the inner cell-collagen part. The constructed hydrogel carriers showed a continuous fiber with a diameter of ∼700–1000 μm for the core and 200–500 μm for the shell area, which was largely dependent on the alginate concentration (2%–5%) as well as the injection rate (20–80 mL/h). The water uptake capacity of the core–shell carriers was as high as 98%, which could act as a pore channel to supply nutrients and oxygen to the cells. Degradation of the scaffolds showed a weight loss of ∼22% at 7 days and ∼43% at 14 days, suggesting a possible role as a degradable tissue-engineered construct. The MSCs encapsulated within the collagen core showed excellent viability, exhibiting significant cellular proliferation up to 21 days with levels comparable to those observed in the pure collagen gel matrix used as a control. A live/dead cell assay also confirmed similar percentages of live cells within the core–shell carrier compared to those in the pure collagen gel, suggesting the carrier was cell compatible and was effective for maintaining a cell population. Cells allowed to differentiate under osteogenic conditions expressed high levels of bone-related genes, including osteocalcin, bone sialoprotein, and osteopontin. Further, when the core–shell fibrous carriers were implanted in a rat calvarium defect, the bone

  20. Scaffolds in Tendon Tissue Engineering

    PubMed Central

    Longo, Umile Giuseppe; Lamberti, Alfredo; Petrillo, Stefano; Maffulli, Nicola; Denaro, Vincenzo

    2012-01-01

    Tissue engineering techniques using novel scaffold materials offer potential alternatives for managing tendon disorders. Tissue engineering strategies to improve tendon repair healing include the use of scaffolds, growth factors, cell seeding, or a combination of these approaches. Scaffolds have been the most common strategy investigated to date. Available scaffolds for tendon repair include both biological scaffolds, obtained from mammalian tissues, and synthetic scaffolds, manufactured from chemical compounds. Preliminary studies support the idea that scaffolds can provide an alternative for tendon augmentation with an enormous therapeutic potential. However, available data are lacking to allow definitive conclusion on the use of scaffolds for tendon augmentation. We review the current basic science and clinical understanding in the field of scaffolds and tissue engineering for tendon repair. PMID:22190961

  1. Osteogenic Differentiation of Human Mesenchymal Stem Cells in Mineralized Alginate Matrices

    PubMed Central

    Westhrin, Marita; Xie, Minli; Olderøy, Magnus Ø.; Sikorski, Pawel

    2015-01-01

    Mineralized biomaterials are promising for use in bone tissue engineering. Culturing osteogenic cells in such materials will potentially generate biological bone grafts that may even further augment bone healing. Here, we studied osteogenic differentiation of human mesenchymal stem cells (MSC) in an alginate hydrogel system where the cells were co-immobilized with alkaline phosphatase (ALP) for gradual mineralization of the microenvironment. MSC were embedded in unmodified alginate beads and alginate beads mineralized with ALP to generate a polymer/hydroxyapatite scaffold mimicking the composition of bone. The initial scaffold mineralization induced further mineralization of the beads with nanosized particles, and scanning electron micrographs demonstrated presence of collagen in the mineralized and unmineralized alginate beads cultured in osteogenic medium. Cells in both types of beads sustained high viability and metabolic activity for the duration of the study (21 days) as evaluated by live/dead staining and alamar blue assay. MSC in beads induced to differentiate in osteogenic direction expressed higher mRNA levels of osteoblast-specific genes (RUNX2, COL1AI, SP7, BGLAP) than MSC in traditional cell cultures. Furthermore, cells differentiated in beads expressed both sclerostin (SOST) and dental matrix protein-1 (DMP1), markers for late osteoblasts/osteocytes. In conclusion, Both ALP-modified and unmodified alginate beads provide an environment that enhance osteogenic differentiation compared with traditional 2D culture. Also, the ALP-modified alginate beads showed profound mineralization and thus have the potential to serve as a bone substitute in tissue engineering. PMID:25769043

  2. Terminal sterilization of alginate hydrogels: efficacy and impact on mechanical properties.

    PubMed

    Stoppel, Whitney L; White, Joseph C; Horava, Sarena D; Henry, Anna C; Roberts, Susan C; Bhatia, Surita R

    2014-05-01

    Terminal, or postprocessing, sterilization of composite biomaterials is crucial for their use in wound healing and tissue-engineered devices. Recent research has focused on optimizing traditional biomaterial formulations to create better products for commercial and academic use which incorporate hydrophobic compounds or secondary gel networks. To use a hydrogel in a clinical setting, terminal sterilization is necessary to ensure patient safety. Lyophilization, gamma-irradiation, and ethylene oxide treatment all have negative consequences when applied to alginate scaffolds for clinical use. Here, we aim to find alternative terminal sterilization methods for alginate and alginate-based composite hydrogels which maintain the structure of composite alginate networks for use in biomedical applications. A thorough investigation of the effect of common sterilization methods on swollen alginate-based hydrogels has not been reported and therefore, this work examines autoclaving, ethanol washing, and ultraviolet light as sterilization techniques for alginate and alginate/Pluronic® F68 composite hydrogels. Preservation of structural integrity is evaluated using shear rheology and analysis of water retention, and efficacy of sterilization is determined via bacterial persistence within the hydrogel. Results indicate that ethanol sterilization is the best method of those investigated because ethanol washing results in minimal effects on mechanical properties and water retention and eliminates bacterial persistence. Furthermore, this study suggests that ethanol treatment is an efficacious method for terminally sterilizing interpenetrating networks or other composite hydrogel systems. PMID:24259507

  3. Dual drug-loaded nanoparticles on self-integrated scaffold for controlled delivery

    PubMed Central

    Bennet, Devasier; Marimuthu, Mohana; Kim, Sanghyo; An, Jeongho

    2012-01-01

    Antioxidant (quercetin) and hypoglycemic (voglibose) drug-loaded poly-D,L-lactideco-glycolide nanoparticles were successfully synthesized using the solvent evaporation method. The dual drug-loaded nanoparticles were incorporated into a scaffold film using a solvent casting method, creating a controlled transdermal drug-delivery system. Key features of the film formulation were achieved utilizing several ratios of excipients, including polyvinyl alcohol, polyethylene glycol, hyaluronic acid, xylitol, and alginate. The scaffold film showed superior encapsulation capability and swelling properties, with various potential applications, eg, the treatment of diabetes-associated complications. Structural and light scattering characterization confirmed a spherical shape and a mean particle size distribution of 41.3 nm for nanoparticles in the scaffold film. Spectroscopy revealed a stable polymer structure before and after encapsulation. The thermoresponsive swelling properties of the film were evaluated according to temperature and pH. Scaffold films incorporating dual drug-loaded nanoparticles showed remarkably high thermoresponsivity, cell compatibility, and ex vivo drug-release behavior. In addition, the hybrid film formulation showed enhanced cell adhesion and proliferation. These dual drug-loaded nanoparticles incorporated into a scaffold film may be promising for development into a transdermal drug-delivery system. PMID:22888222

  4. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown...

  5. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  6. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  7. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  8. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  9. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  10. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  11. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  12. Influence of structural load-bearing scaffolds on mechanical load- and BMP-2-mediated bone regeneration.

    PubMed

    McDermott, Anna M; Mason, Devon E; Lin, Angela S P; Guldberg, Robert E; Boerckel, Joel D

    2016-09-01

    A common design constraint in functional tissue engineering is that scaffolds intended for use in load-bearing sites possess similar mechanical properties to the replaced tissue. Here, we tested the hypothesis that in vivo loading would enhance bone morphogenetic protein-2 (BMP-2)-mediated bone regeneration in the presence of a load-bearing PLDL scaffold, whose pores and central core were filled with BMP-2-releasing alginate hydrogel. First, we evaluated the effects of in vivo mechanical loading on bone regeneration in the structural scaffolds. Second, we compared scaffold-mediated bone regeneration, independent of mechanical loading, with alginate hydrogel constructs, without the structural scaffold, that have been shown previously to facilitate in vivo mechanical stimulation of bone formation. Contrary to our hypothesis, mechanical loading had no effect on bone formation, distribution, or biomechanical properties in structural scaffolds. Independent of loading, the structural scaffolds reduced bone formation compared to non-structural alginate, particularly in regions in which the scaffold was concentrated, resulting in impaired functional regeneration. This is attributable to a combination of stress shielding by the scaffold and inhibition of cellular infiltration and tissue ingrowth. Collectively, these data question the necessity of scaffold similarity to mature tissue at the time of implantation and emphasize development of an environment conducive to cellular activation of matrix production and ultimate functional regeneration. PMID:27208510

  13. Microbial alginate production, modification and its applications

    PubMed Central

    Hay, Iain D; Rehman, Zahid Ur; Moradali, M Fata; Wang, Yajie; Rehm, Bernd H A

    2013-01-01

    Alginate is an important polysaccharide used widely in the food, textile, printing and pharmaceutical industries for its viscosifying, and gelling properties. All commercially produced alginates are isolated from farmed brown seaweeds. These algal alginates suffer from heterogeneity in composition and material properties. Here, we will discuss alginates produced by bacteria; the molecular mechanisms involved in their biosynthesis; and the potential to utilize these bacterially produced or modified alginates for high-value applications where defined material properties are required. PMID:24034361

  14. Sustained Delivery of Bioactive GDNF from Collagen and Alginate-Based Cell-Encapsulating Gel Promoted Photoreceptor Survival in an Inherited Retinal Degeneration Model

    PubMed Central

    Chan, Barbara P.; Lo, Amy C. Y.

    2016-01-01

    Encapsulated-cell therapy (ECT) is an attractive approach for continuously delivering freshly synthesized therapeutics to treat sight-threatening posterior eye diseases, circumventing repeated invasive intravitreal injections and improving local drug availability clinically. Composite collagen-alginate (CAC) scaffold contains an interpenetrating network that integrates the physical and biological merits of its constituents, including biocompatibility, mild gelling properties and availability. However, CAC ECT properties and performance in the eye are not well-understood. Previously, we reported a cultured 3D CAC system that supported the growth of GDNF-secreting HEK293 cells with sustainable GDNF delivery. Here, the system was further developed into an intravitreally injectable gel with 1x104 or 2x105 cells encapsulated in 2mg/ml type I collagen and 1% alginate. Gels with lower alginate concentration yielded higher initial cell viability but faster spheroid formation while increasing initial cell density encouraged cell growth. Continuous GDNF delivery was detected in culture and in healthy rat eyes for at least 14 days. The gels were well-tolerated with no host tissue attachment and contained living cell colonies. Most importantly, gel-implanted in dystrophic Royal College of Surgeons rat eyes for 28 days retained photoreceptors while those containing higher initial cell number yielded better photoreceptor survival. CAC ECT gels offers flexible system design and is a potential treatment option for posterior eye diseases. PMID:27441692

  15. Sustained Delivery of Bioactive GDNF from Collagen and Alginate-Based Cell-Encapsulating Gel Promoted Photoreceptor Survival in an Inherited Retinal Degeneration Model.

    PubMed

    Wong, Francisca S Y; Wong, Calvin C H; Chan, Barbara P; Lo, Amy C Y

    2016-01-01

    Encapsulated-cell therapy (ECT) is an attractive approach for continuously delivering freshly synthesized therapeutics to treat sight-threatening posterior eye diseases, circumventing repeated invasive intravitreal injections and improving local drug availability clinically. Composite collagen-alginate (CAC) scaffold contains an interpenetrating network that integrates the physical and biological merits of its constituents, including biocompatibility, mild gelling properties and availability. However, CAC ECT properties and performance in the eye are not well-understood. Previously, we reported a cultured 3D CAC system that supported the growth of GDNF-secreting HEK293 cells with sustainable GDNF delivery. Here, the system was further developed into an intravitreally injectable gel with 1x104 or 2x105 cells encapsulated in 2mg/ml type I collagen and 1% alginate. Gels with lower alginate concentration yielded higher initial cell viability but faster spheroid formation while increasing initial cell density encouraged cell growth. Continuous GDNF delivery was detected in culture and in healthy rat eyes for at least 14 days. The gels were well-tolerated with no host tissue attachment and contained living cell colonies. Most importantly, gel-implanted in dystrophic Royal College of Surgeons rat eyes for 28 days retained photoreceptors while those containing higher initial cell number yielded better photoreceptor survival. CAC ECT gels offers flexible system design and is a potential treatment option for posterior eye diseases. PMID:27441692

  16. Calcium-Alginate Hydrogel-Encapsulated Fibroblasts Provide Sustained Release of Vascular Endothelial Growth Factor

    PubMed Central

    Hunt, Nicola C.; Shelton, Richard M.; Henderson, Deborah J.

    2013-01-01

    Vascularization of engineered or damaged tissues is essential to maintain cell viability and proper tissue function. Revascularization of the left ventricle (LV) of the heart after myocardial infarction is particularly important, since hypoxia can give rise to chronic heart failure due to inappropriate remodeling of the LV after death of cardiomyocytes (CMs). Fibroblasts can express vascular endothelial growth factor (VEGF), which plays a major role in angiogenesis and also acts as a chemoattractant and survival factor for CMs and cardiac progenitors. In this in vitro model study, mouse NIH 3T3 fibroblasts encapsulated in 2% w/v Ca-alginate were shown to remain viable for 150 days. Semiquantitative reverse transcription–polymerase chain reaction and immunohistochemistry demonstrated that over 21 days of encapsulation, fibroblasts continued to express VEGF, while enzyme-linked immunosorbent assay showed that there was sustained release of VEGF from the Ca-alginate during this period. The scaffold degraded gradually over the 21 days, without reduction in volume. Cells released from the Ca-alginate at 7 and 21 days as a result of scaffold degradation were shown to retain viability, to adhere to fibronectin in a normal manner, and continue to express VEGF, demonstrating their potential to further contribute to maintenance of cardiac function after scaffold degradation. This model in vitro study therefore demonstrates that fibroblasts encapsulated in Ca-alginate provide sustained release of VEGF. PMID:23082964

  17. Mimicking Metastases Including Tumor Stroma: A New Technique to Generate a Three-Dimensional Colorectal Cancer Model Based on a Biological Decellularized Intestinal Scaffold.

    PubMed

    Nietzer, Sarah; Baur, Florentin; Sieber, Stefan; Hansmann, Jan; Schwarz, Thomas; Stoffer, Carolin; Häfner, Heide; Gasser, Martin; Waaga-Gasser, Ana Maria; Walles, Heike; Dandekar, Gudrun

    2016-07-01

    Tumor models based on cancer cell lines cultured two-dimensionally (2D) on plastic lack histological complexity and functionality compared to the native microenvironment. Xenogenic mouse tumor models display higher complexity but often do not predict human drug responses accurately due to species-specific differences. We present here a three-dimensional (3D) in vitro colon cancer model based on a biological scaffold derived from decellularized porcine jejunum (small intestine submucosa+mucosa, SISmuc). Two different cell lines were used in monoculture or in coculture with primary fibroblasts. After 14 days of culture, we demonstrated a close contact of human Caco2 colon cancer cells with the preserved basement membrane on an ultrastructural level as well as morphological characteristics of a well-differentiated epithelium. To generate a tissue-engineered tumor model, we chose human SW480 colon cancer cells, a reportedly malignant cell line. Malignant characteristics were confirmed in 2D cell culture: SW480 cells showed higher vimentin and lower E-cadherin expression than Caco2 cells. In contrast to Caco2, SW480 cells displayed cancerous characteristics such as delocalized E-cadherin and nuclear location of β-catenin in a subset of cells. One central drawback of 2D cultures-especially in consideration of drug testing-is their artificially high proliferation. In our 3D tissue-engineered tumor model, both cell lines showed decreased numbers of proliferating cells, thus correlating more precisely with observations of primary colon cancer in all stages (UICC I-IV). Moreover, vimentin decreased in SW480 colon cancer cells, indicating a mesenchymal to epithelial transition process, attributed to metastasis formation. Only SW480 cells cocultured with fibroblasts induced the formation of tumor-like aggregates surrounded by fibroblasts, whereas in Caco2 cocultures, a separate Caco2 cell layer was formed separated from the fibroblast compartment beneath. To foster tissue

  18. Mimicking Metastases Including Tumor Stroma: A New Technique to Generate a Three-Dimensional Colorectal Cancer Model Based on a Biological Decellularized Intestinal Scaffold

    PubMed Central

    Nietzer, Sarah; Baur, Florentin; Sieber, Stefan; Hansmann, Jan; Schwarz, Thomas; Stoffer, Carolin; Häfner, Heide; Gasser, Martin; Waaga-Gasser, Ana Maria; Walles, Heike

    2016-01-01

    Tumor models based on cancer cell lines cultured two-dimensionally (2D) on plastic lack histological complexity and functionality compared to the native microenvironment. Xenogenic mouse tumor models display higher complexity but often do not predict human drug responses accurately due to species-specific differences. We present here a three-dimensional (3D) in vitro colon cancer model based on a biological scaffold derived from decellularized porcine jejunum (small intestine submucosa+mucosa, SISmuc). Two different cell lines were used in monoculture or in coculture with primary fibroblasts. After 14 days of culture, we demonstrated a close contact of human Caco2 colon cancer cells with the preserved basement membrane on an ultrastructural level as well as morphological characteristics of a well-differentiated epithelium. To generate a tissue-engineered tumor model, we chose human SW480 colon cancer cells, a reportedly malignant cell line. Malignant characteristics were confirmed in 2D cell culture: SW480 cells showed higher vimentin and lower E-cadherin expression than Caco2 cells. In contrast to Caco2, SW480 cells displayed cancerous characteristics such as delocalized E-cadherin and nuclear location of β-catenin in a subset of cells. One central drawback of 2D cultures—especially in consideration of drug testing—is their artificially high proliferation. In our 3D tissue-engineered tumor model, both cell lines showed decreased numbers of proliferating cells, thus correlating more precisely with observations of primary colon cancer in all stages (UICC I-IV). Moreover, vimentin decreased in SW480 colon cancer cells, indicating a mesenchymal to epithelial transition process, attributed to metastasis formation. Only SW480 cells cocultured with fibroblasts induced the formation of tumor-like aggregates surrounded by fibroblasts, whereas in Caco2 cocultures, a separate Caco2 cell layer was formed separated from the fibroblast compartment beneath. To foster tissue

  19. Using Scaffolds in Problem-Based Hypermedia

    ERIC Educational Resources Information Center

    Su, Yuyan; Klein, James D.

    2010-01-01

    This study investigated the use of scaffolds in problem-based hypermedia. Three hundred and twelve undergraduate students enrolled in a computer literacy course worked in project teams to use a hypermedia PBL program focused on designing a personal computer. The PBL program included content scaffolds, metacognitive scaffolds, or no scaffolds.…

  20. Hierarchical scaffolding with Bambus.

    PubMed

    Pop, Mihai; Kosack, Daniel S; Salzberg, Steven L

    2004-01-01

    The output of a genome assembler generally comprises a collection of contiguous DNA sequences (contigs) whose relative placement along the genome is not defined. A procedure called scaffolding is commonly used to order and orient these contigs using paired read information. This ordering of contigs is an essential step when finishing and analyzing the data from a whole-genome shotgun project. Most recent assemblers include a scaffolding module; however, users have little control over the scaffolding algorithm or the information produced. We thus developed a general-purpose scaffolder, called Bambus, which affords users significant flexibility in controlling the scaffolding parameters. Bambus was used recently to scaffold the low-coverage draft dog genome data. Most significantly, Bambus enables the use of linking data other than that inferred from mate-pair information. For example, the sequence of a completed genome can be used to guide the scaffolding of a related organism. We present several applications of Bambus: support for finishing, comparative genomics, analysis of the haplotype structure of genomes, and scaffolding of a mammalian genome at low coverage. Bambus is available as an open-source package from our Web site. PMID:14707177

  1. Alginate Hydrogel: A Shapeable and Versatile Platform for in Situ Preparation of Metal-Organic Framework-Polymer Composites.

    PubMed

    Zhu, He; Zhang, Qi; Zhu, Shiping

    2016-07-13

    This work reports a novel in situ growth approach for incorporating metal-organic framework (MOF) materials into an alginate substrate, which overcomes the challenges of processing MOF particles into specially shaped structures for real industrial applications. The MOF-alginate composites are prepared through the post-treatment of a metal ion cross-linked alginate hydrogel with a MOF ligand solution. MOF particles are well distributed and embedded in and on the surface of the composites. The macroscopic shape of the composite can be designed by controlling the shape of the corresponding hydrogel; thus MOF-alginate beads, fibers, and membranes are obtained. In addition, four different MOF-alginate composites, including HKUST-1-, ZIF-8-, MIL-100(Fe)-, and ZIF-67-alginate, were successfully prepared using different metal ion cross-linked alginate hydrogels. The mechanism of formation is revealed, and the composite is demonstrated to be an effective absorbent for water purification. PMID:27315047

  2. Controllable 3D alginate hydrogel patterning via visible-light induced electrodeposition.

    PubMed

    Dai, Gaole; Wan, Wenfeng; Zhao, Yuliang; Wang, Zixun; Li, Wenjun; Shi, Peng; Shen, Yajing

    2016-01-01

    The fabrication of alginate hydrogel in 3D has recently received increasing attention owing to its distinct efficacy as biocompatible scaffold for 3D cell culture, biomedical and tissue engineering. We report a controllable 3D alginate hydrogel patterning method by developing a visible-light induced electrodeposition chip. The chip mainly consists of a photoconductive titanyl phthalocyanine (TiOPc) anode plate, an indium tin oxide (ITO) cathode plate and the mixed solution (1% sodium alginate and 0.25% CaCO3 nano particles) between them. After a designed visible-light pattern is projected onto the TiOPc plate, the produced H(+) by electrolysis will trigger Ca(2+) near the anode (illuminated area), and then the gelation of calcium alginate patterns, as desired, happens controllably. In addition, we further establish an exponential model to elucidate the gel growth v.s. time and current density. The results indicate that the proposed method is able to fabricate various 3D alginate hydrogel patterns in a well controllable manner, and maintain the laden cells at high survival rate (>98% right after gel formation). This research paves an alternative way for 3D alginate hydrogel patterning with high controllability and productivity, which would benefit the research in biomedical and tissue engineering. PMID:27108617

  3. Fabrication of freestanding alginate microfibers and microstructures for tissue engineering applications.

    PubMed

    Szymanski, John M; Feinberg, Adam W

    2014-06-01

    Natural biopolymers such as alginate have become important materials for a variety of biotechnology applications including drug delivery, cell encapsulation and tissue engineering. This expanding use has spurred the development of new approaches to engineer these materials at the nano- and microscales to better control cell interactions. Here we describe a method to fabricate freestanding alginate-based microfibers and microstructures with tunable geometries down to approximately 3 µm. To do this, a polydimethylsiloxane stamp is used to micromold alginate or alginate-fibrin blends onto a sacrificial layer of thermally-sensitive poly(N-isopropylacrylamide) (PIPAAm). A warm calcium chloride solution is then used to crosslink the alginate and, upon cooling below the lower critical solution temperature (~32 °C), the PIPAAm layer dissolves and releases the alginate or alginate-fibrin as freestanding microfibers and microstructures. Proof-of-concept experiments demonstrate that C2C12 myoblasts seeded onto the alginate-fibrin microfibers polarize along the fiber length forming interconnected cell strands. Thus, we have developed the ability to engineer alginate-based microstructured materials that can selectively bind cells and direct cellular assembly. PMID:24695323

  4. Controlled mineralisation and recrystallisation of brushite within alginate hydrogels.

    PubMed

    Bjørnøy, Sindre H; Bassett, David C; Ucar, Seniz; Andreassen, Jens-Petter; Sikorski, Pawel

    2016-02-01

    Due to high solubility and fast resorption behaviour under physiological conditions, brushite (CaHPO4⋅2H2O, calcium monohydrogen phosphate dihydrate, dicalcium phosphate dihydrate) has great potential in bone regeneration applications, both in combination with scaffolds or as a component of calcium phosphate cements. The use of brushite in combination with hydrogels opens up possibilities for new cell-based tissue engineering applications of this promising material. However, published preparation methods of brushite composites, in which the mineral phase is precipitated within the hydrogel network, fail to offer the necessary degree of control over the mineral phase, content and distribution within the hydrogel matrix. The main focus of this study is to address these shortcomings by determining the precise fabrication parameters needed to prepare composites with controlled composition and properties. Composite alginate microbeads were prepared using a counter-diffusion technique, which allows for the simultaneous crosslinking of the hydrogel and precipitation of an inorganic mineral phase. Reliable nucleation of a desired mineral phase within the alginate network proved more challenging than simple aqueous precipitation. This was largely due to ion transport within the hydrogel producing concentration gradients that modified levels of supersaturation and favoured the nucleation of other phases such as hydroxyapatite and octacalcium phosphate, which would otherwise not form. To overcome this, the incorporation of brushite seed crystals resulted in good control during the mineral phase, and by adjusting the number of seeds and amount of precursor concentration, the amount of mineral could be tuned. The material was characterised with a range of physical techniques, including scanning electron microscopy, powder x-ray diffraction and Rietveld refinement, Fourier transform infrared spectroscopy, and thermogravimetric analysis, in order to assess the mineral

  5. A honeycomb composite of mollusca shell matrix and calcium alginate.

    PubMed

    You, Hua-jian; Li, Jin; Zhou, Chan; Liu, Bin; Zhang, Yao-guang

    2016-03-01

    A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205-496% and 417-586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering. PMID:26700239

  6. Modular Injectable Matrices Based on Alginate Solution/Microsphere Mixtures That Gel in situ and Co-Deliver Immunomodulatory Factors

    PubMed Central

    Hori, Yuki; Winans, Amy M.; Irvine, Darrell J.

    2011-01-01

    Biocompatible polymer solutions that can crosslink in situ following injection to form stable hydrogels are of interest as depots for sustained delivery of therapeutic factors or cells, and as scaffolds for regenerative medicine. Here, injectable self-gelling alginate formulations obtained by mixing alginate microspheres (as calcium reservoirs) with soluble alginate solutions were characterized for potential use in immunotherapy. Rapid redistribution of calcium ions from microspheres into the surrounding alginate solution led to rapid crosslinking and formation of stable hydrogels. The mechanical properties of the resulting gels correlated with the concentration of calcium reservoir microspheres added to the solution. Soluble factors such as the cytokine interleukin-2 were readily incorporated into self-gelling alginate matrices by simply mixing them with the formulation prior to gelation. Using alginate microspheres as modular components, strategies for binding immunostimulatory CpG oligonucleotides onto the surface of microspheres were also demonstrated. When injected subcutaneously in the flanks of mice, self-gelling alginate formed soft macroporous gels supporting cellular infiltration and allowing ready access to microspheres carrying therapeutic factors embedded in the matrix. This in-situ gelling formulation may thus be useful for stimulating immune cells at a desired locale such as solid tumors or infection sites as well as for other soft tissue regeneration applications. PMID:19117820

  7. Structural Characterization of Sodium Alginate and Calcium Alginate.

    PubMed

    Hecht, Hadas; Srebnik, Simcha

    2016-06-13

    Alginate readily aggregates and forms a physical gel in the presence of cations. The association of the chains, and ultimately gel structure and mechanics, depends not only on ion type, but also on the sequence and composition of the alginate chain that ultimately determines its stiffness. Chain flexibility is generally believed to decrease with guluronic residue content, but it is also known that both polymannuronate and polyguluronate blocks are stiffer than heteropolymeric blocks. In this work, we use atomistic molecular dynamics simulation to primarily explore the association and aggregate structure of different alginate chains under various Ca(2+) concentrations and for different alginate chain composition. We show that Ca(2+) ions in general facilitate chain aggregation and gelation. However, aggregation is predominantly affected by alginate monomer composition, which is found to correlate with chain stiffness under certain solution conditions. In general, greater fractions of mannuronic monomers are found to increase chain flexibility of heteropolymer chains. Furthermore, differences in chain guluronic acid content are shown to lead to different interchain association mechanisms, such as lateral association, zipper mechanism, and entanglement, where the mannuronic residues are shown to operate as an elasticity moderator and therefore promote chain association. PMID:27177209

  8. Coaxial additive manufacture of biomaterial composite scaffolds for tissue engineering.

    PubMed

    Cornock, R; Beirne, S; Thompson, B; Wallace, G G

    2014-06-01

    An inherent difficulty associated with the application of suitable bioscaffolds for tissue engineering is the incorporation of adequate mechanical characteristics into the materials which recapitulate that of the native tissue, whilst maintaining cell proliferation and nutrient transfer qualities. Biomaterial composites fabricated using rapid prototyping techniques can potentially improve the functionality and patient-specific processing of tissue engineering scaffolds. In this work, a technique for the coaxial melt extrusion printing of core-shell scaffold structures was designed, implemented and assessed with respect to the repeatability, cell efficacy and scaffold porosity obtainable. Encapsulated alginate hydrogel/thermoplastic polycaprolactone (Alg-PCL) cofibre scaffolds were fabricated. Selective laser melting was used to produce a high resolution stainless steel 316 L coaxial extrusion nozzle, exhibiting diameters of 300 μm/900 μm for the inner and outer nozzles respectively. We present coaxial melt extrusion printed scaffolds of Alg-PCL cofibres with ~0.4 volume fraction alginate, with total fibre diameter as low as 600 μm and core material offset as low as 10% of the total diameter. Furthermore the tuneability of scaffold porosity, pore size and interconnectivity, as well as the preliminary inclusion, compatibility and survival of an L-929 mouse fibroblast cell-line within the scaffolds were explored. This preliminary cell work highlighted the need for optimal material selection and further design reiteration in future research. PMID:24658021

  9. 21 CFR 582.7187 - Calcium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is...

  10. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  11. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  12. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  13. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  14. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  15. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  16. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  17. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  18. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  19. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  20. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  1. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1011 Alginic acid. (a) Alginic acid is a colloidal, hydrophilic polysaccharide obtained from...

  2. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  3. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  4. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  5. Nonlinear elasticity of alginate gels

    NASA Astrophysics Data System (ADS)

    Hashemnejad, Seyed Meysam; Kundu, Santanu

    Alginate is a naturally occurring anionic polysaccharide extracted from brown algae. Because of biocompatibility, low toxicity, and simple gelation process, alginate gels are used in biomedical and food applications. Here, we report the rheological behavior of ionically crosslinked alginate gels, which are obtained by in situ gelation of alginates with calcium salts, in between two parallel plates of a rheometer. Strain stiffening behavior was captured using large amplitude oscillatory shear (LAOS) experiments. In addition, negative normal stress was observed for these gels, which has not been reported earlier for any polysaccharide networks. The magnitude of negative normal stress increases with applied strain and can exceed that of the shear stress at large strain. Rheological results fitted with a constitutive model that considers both stretching and bending of chains indicate that nonlinearity is likely related to the stretching of the chains between the crosslink junctions. The results provide an improved understanding of the deformation mechanism of ionically crosslinked alginate gel and the results will be important in developing synthetic extracellular matrix (ECM) from these materials.

  6. The effect of calcium chloride concentration on alginate/Fmoc-diphenylalanine hydrogel networks.

    PubMed

    Çelik, Ekin; Bayram, Cem; Akçapınar, Rümeysa; Türk, Mustafa; Denkbaş, Emir Baki

    2016-09-01

    Peptide based hydrogels gained a vast interest in the tissue engineering studies thanks to great superiorities such as biocompatibility, supramolecular organization without any need of additional crosslinker, injectability and tunable nature. Fmoc-diphenylalanine (FmocFF) is one of the earliest and widely used example of these small molecule gelators that have been utilized in biomedical studies. However, Fmoc-peptides are not feasible for long term use due to low stability and weak mechanical properties at neutral pH. In this study, Fmoc-FF dipeptides were mechanically enhanced by incorporation of alginate, a biocompatible and absorbable polysaccharide. The binary hydrogel is obtained via molecular self-assembly of FmocFF dipeptide in alginate solution followed by ionic crosslinking of alginate moieties with varying concentrations of calcium chloride. Hydrogel characterization was evaluated in terms of morphology, viscoelastic moduli and diffusional phenomena and the structures were tested as 3D scaffolds for bovine chondrocytes. In vitro evaluation of scaffolds lasted up to 14days and cell viability, sulphated glycosaminoglycan (sGAG) levels, collagen type II synthesis were determined. Our results showed that alginate incorporation into FmocFF hydrogels leads to better mechanical properties and higher stability with good biocompatibility. PMID:27207058

  7. Superabsorbent nanocomposite (alginate-g-PAMPS/MMT): synthesis, characterization and swelling behavior.

    PubMed

    Yadav, Mithilesh; Rhee, Kyong Yop

    2012-09-01

    A superabsorbent composite (alginate-g-PAMPS/MMT) was prepared by graft copolymerization from alginate, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and Na+ montmorillonite (MMT) in an inert atmosphere. Effects of polymerization variables on water absorbency, including the content of Na+ montmorillonite, sodium alginate, N,N'-methylenebisacrylamide and AMPS, were studied. The introduced montmorillonite formed a loose and porous surface and improved the water absorbency of the alginate-g-PAMPS/MMT superabsorbent composite. Swelling behaviors of the superabsorbent composites in various cationic salt solutions (NaCl, CaCl2 and FeCl3) and anionic salt solutions (NaCl and Na2SO4) were also systematically investigated. The superabsorbent composite was further characterized using Fourier transform infrared spectroscopy (FTIR), rheology, thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) taking alginate-g-PAMPS as a reference. PMID:24751026

  8. Multi-featured macroporous agarose-alginate cryogel: synthesis and characterization for bioengineering applications.

    PubMed

    Tripathi, Anuj; Kumar, Ashok

    2011-01-10

    In this study agarose-alginate scaffolds are synthesized using cryogelation technology in different formats like monolith, sheet, discs, and beads, and show amiable mechanical strength like soft tissue properties and high interconnected macroporous degradable architecture. In cell-material interactions, fibroblast (NIH-3T3) cells showed good adherence and proliferation on these scaffolds presenting its potential application in soft tissue engineering. The application of cryogel beads and monoliths was also examined by the efficient immobilization of bacterial cells (BL21) on these matrices revealing their use for recovery of product from continuous fermentation systems without cell leakage. These scaffolds also showed potential as a filter for repeated recovery of heavy metal binding, such as copper and nickel from the waste water. The cryogels prepared herein do have a number of unique features that make them an important class of soft materials for developing multi-featured scaffolds as a novel carrier for bioengineering applications. PMID:21077225

  9. Postelectrospinning modifications for alginate nanofiber-based wound dressings.

    PubMed

    Leung, Victor; Hartwell, Ryan; Elizei, Sanam Salimi; Yang, Heejae; Ghahary, Aziz; Ko, Frank

    2014-04-01

    Alginate nanofibers have been attractive for potential tissue regeneration applications due to a combination of their moisture retention ability and large surface area available in a nonwoven nanofiber form. This study aims to address several challenges in alginate nanofiber application, including the lack of structural stability in aqueous environment and limited cell attachment as compared to commercial wound dressings, via examining crosslinking techniques. In addition to the commonly performed divalent ion crosslinking, a glutaraldehyde double-crosslinking step and polylysine addition were applied to an electrospun alginate nanofiber nonwoven mat. With optimization of the electrospinning solution, nanofiber morphology was maintained after the two-stage crosslinking process. Extensibility of the nanofiber mat reduced after the crosslinking process. However, both aqueous stability and cell attachment improved after the postspinning modifications, as shown through degradation tests in phosphate buffered saline solutions and fibroblast cell culture studies, respectively. PMID:24155096

  10. Scaffolding and Metacognition

    ERIC Educational Resources Information Center

    Holton, Derek; Clarke, David

    2006-01-01

    This paper proposes an expanded conception of scaffolding with four key elements: (1) scaffolding agency--expert, reciprocal, and self-scaffolding; (2) scaffolding domain--conceptual and heuristic scaffolding; (3) the identification of self-scaffolding with metacognition; and (4) the identification of six zones of scaffolding activity; each zone…

  11. Detoxification of Hg(II) from aqueous and enzyme media: Pristine vs. tailored calcium alginate hydrogels.

    PubMed

    Sarkar, Kangkana; Ansari, Zarina; Sen, Kamalika

    2016-10-01

    Calcium alginate (CA) hydrogels were tailored using phenolic compounds (PC) like, thymol, morin, catechin, hesperidin, during their preparation. The PC incorporated gels show modified surface features as indicated by scanning electron microscopic images (SEM). The rheological studies show that excepting the hesperidin incorporated gels all the other kinds including calcium alginate pristine have similar mechanical strength. The hesperidine incorporated CA gels had the maximum capacity to adsorb Hg. The Freundlich adsorption isotherms show higher values of adsorption capacity for all PC incorporated CA beads than the pristine CA (PCA). The hesperidin incorporated CA gels were found to show the best adsorption condition at neutral pH and an optimum contact time of 2.5h at 25°C. Considering the possibility of ingested Hg detoxification from human alimentary tract, the hesperidin and morin incorporated CA beads were further modified through incorporation of cod liver oil as the digestion time of fat in stomach is higher. In vitro uptake capacities of Hg in pepsin and pancreatin containing enzyme media were studied with hesperidin and morin incorporated beads and their corresponding fat incorporated beads also. In the pepsin medium, there was no uptake by hesperidin and fat-hesperidin incorporated beads, which is possibly due to the higher acidity of the medium. But in pancreatin medium Hg was taken up by both kinds of beads. Morin and morin-fat incorporated beads were efficient to uptake Hg from both the pepsin and pancreatin medium. The tailored CA beads may therefore serve as efficient scaffolds to rescue Hg ingested individuals. PMID:27208797

  12. Scaffolded biology.

    PubMed

    Minelli, Alessandro

    2016-09-01

    Descriptions and interpretations of the natural world are dominated by dichotomies such as organism vs. environment, nature vs. nurture, genetic vs. epigenetic, but in the last couple of decades strong dissatisfaction with those partitions has been repeatedly voiced and a number of alternative perspectives have been suggested, from perspectives such as Dawkins' extended phenotype, Turner's extended organism, Oyama's Developmental Systems Theory and Odling-Smee's niche construction theory. Last in time is the description of biological phenomena in terms of hybrids between an organism (scaffolded system) and a living or non-living scaffold, forming unit systems to study processes such as reproduction and development. As scaffold, eventually, we can define any resource used by the biological system, especially in development and reproduction, without incorporating it as happens in the case of resources fueling metabolism. Addressing biological systems as functionally scaffolded systems may help pointing to functional relationships that can impart temporal marking to the developmental process and thus explain its irreversibility; revisiting the boundary between development and metabolism and also regeneration phenomena, by suggesting a conceptual framework within which to investigate phenomena of regular hypermorphic regeneration such as characteristic of deer antlers; fixing a periodization of development in terms of the times at which a scaffolding relationship begins or is terminated; and promoting plant galls to legitimate study objects of developmental biology. PMID:27287514

  13. Quantification of alginate by aggregation induced by calcium ions and fluorescent polycations.

    PubMed

    Zheng, Hewen; Korendovych, Ivan V; Luk, Yan-Yeung

    2016-01-01

    For quantification of polysaccharides, including heparins and alginates, the commonly used carbazole assay involves hydrolysis of the polysaccharide to form a mixture of UV-active dye conjugate products. Here, we describe two efficient detection and quantification methods that make use of the negative charges of the alginate polymer and do not involve degradation of the targeted polysaccharide. The first method utilizes calcium ions to induce formation of hydrogel-like aggregates with alginate polymer; the aggregates can be quantified readily by staining with a crystal violet dye. This method does not require purification of alginate from the culture medium and can measure the large amount of alginate that is produced by a mucoid Pseudomonas aeruginosa culture. The second method employs polycations tethering a fluorescent dye to form suspension aggregates with the alginate polyanion. Encasing the fluorescent dye in the aggregates provides an increased scattering intensity with a sensitivity comparable to that of the conventional carbazole assay. Both approaches provide efficient methods for monitoring alginate production by mucoid P. aeruginosa. PMID:26408812

  14. The enhancement of chondrogenesis of ATDC5 cells in RGD-immobilized microcavitary alginate hydrogels.

    PubMed

    Yao, Yongchang; Zeng, Lei; Huang, Yuyang

    2016-07-01

    In our previous work, we have developed an effective microcavitary alginate hydrogel for proliferation of chondrocytes and maintenance of chondrocytic phenotype. In present work, we investigated whether microcavitary alginate hydrogel could promote the chondrogenesis of progenitor cells. Moreover, we attempted to further optimize this system by incorporating synthetic Arg-Gly-Asp peptide. ATDC5 cells were seeded into microcavitary alginate hydrogel with or without Arg-Gly-Asp immobilization. Cell Counting Kit-8 and live/dead staining were conducted to analyze cell proliferation. Real-time polymerase chain reaction (RT-PCR), hematoxylin and eosin, and Toluidine blue O staining as well as Western blot assay was performed to evaluate the cartilaginous markers at transcriptional level and at protein level, respectively. The obtained data demonstrated that Arg-Gly-Asp-immobilized microcavitary alginate hydrogel was preferable to promote the cell proliferation. Also, Arg-Gly-Asp-immobilized microcavitary alginate hydrogel improved the expression of chondrocytic genes including Collagen II and Aggrecan when compared with microcavitary alginate hydrogel. The results suggested that microcavitary alginate hydrogel could promote the chondrogenesis. And Arg-Gly-Asp would be promising to ameliorate this culture system for cartilage tissue engineering. PMID:27000189

  15. Imaging Contrast Effects in Alginate Microbeads

    NASA Astrophysics Data System (ADS)

    Shapley, Nina; Hester-Reilly, Holly

    2007-03-01

    We have investigated the use of alginate gel microbeads as contrast agents for the study of suspension flows in complex geometries using nuclear magnetic resonance (NMR) imaging. These deformable particles can provide imaging contrast to rigid polymer particles in a bimodal suspension (two particle sizes). Microbeads were formed of crosslinked alginate gel, with or without trapped oil droplets. Crosslinking of the aqueous sodium alginate solution or the continuous phase of an oil-in-water emulsion occurred rapidly at gentle processing conditions. The alginate microbeads exhibit both spin-spin relaxation time (T2) contrast and diffusion contrast relative to both the suspending fluid and rigid polystyrene particles. Large alginate emulsion microbeads flowing in the abrupt, axisymmetric expansion geometry can be clearly distinguished from the suspending fluid and from rigid polymer particles in both spin-echo and diffusion weighted imaging. The alginate microbeads, particularly those containing trapped emulsion droplets, offer potential as a positive contrast agent in multiple NMR imaging applications.

  16. Photo-crosslinked Alginate Hydrogels Support Enhanced Matrix Accumulation by Nucleus Pulposus Cells In Vivo

    PubMed Central

    Chou, Alice I.; Akintoye, Sunday O.; Nicoll, Steven B.

    2009-01-01

    Objective Intervertebral disc (IVD) degeneration is a major health concern in the United States. Replacement of the nucleus pulposus (NP) with injectable biomaterials represents a potential treatment strategy for IVD degeneration. The objective of this study was to characterize the extracellular matrix assembly and functional properties of NP cell-encapsulated, photo-crosslinked alginate hydrogels in comparison to ionically crosslinked alginate constructs. Methods Methacrylated alginate was synthesized by esterification of hydroxyl groups with methacrylic anhydride. Bovine nucleus pulposus cells were encapsulated in alginate hydrogels by ionic crosslinking using CaCl2 or through photo-crosslinking upon exposure to long-wave UV light in the presence of a photoinitiator. The hydrogels were evaluated in vitro by gross and histological analysis and in vivo using a murine subcutaneous pouch model. In vivo samples were analyzed for gene expression, extracellular matrix localization and accumulation, and equilibrium mechanical properties. Results Ionically crosslinked hydrogels exhibited inferior proteoglycan accumulation in vitro and were unable to maintain structural integrity in vivo. In further studies, photo-crosslinked alginate hydrogels were implanted for up to 8 weeks to examine NP tissue formation. Photo-crosslinked hydrogels displayed temporal increases in gene expression and assembly of type II collagen and proteoglycans. Additionally, hydrogels remained intact over the duration of the study and the equilibrium Young’s modulus increased from 1.24 ± 0.09 kPa to 4.31 ± 1.39 kPa, indicating the formation of functional matrix with properties comparable to those of the native NP. Conclusions These findings support the use of photo-crosslinked alginate hydrogels as biomaterial scaffolds for NP replacement. PMID:19427928

  17. Three-dimensional bioprinting of complex cell laden alginate hydrogel structures.

    PubMed

    Tabriz, Atabak Ghanizadeh; Hermida, Miguel A; Leslie, Nicholas R; Shu, Wenmiao

    2015-01-01

    Different bioprinting techniques have been used to produce cell-laden alginate hydrogel structures, however these approaches have been limited to 2D or simple three-dimension (3D) structures. In this study, a new extrusion based bioprinting technique was developed to produce more complex alginate hydrogel structures. This was achieved by dividing the alginate hydrogel cross-linking process into three stages: primary calcium ion cross-linking for printability of the gel, secondary calcium cross-linking for rigidity of the alginate hydrogel immediately after printing and tertiary barium ion cross-linking for long-term stability of the alginate hydrogel in culture medium. Simple 3D structures including tubes were first printed to ensure the feasibility of the bioprinting technique and then complex 3D structures such as branched vascular structures were successfully printed. The static stiffness of the alginate hydrogel after printing was 20.18 ± 1.62 KPa which was rigid enough to sustain the integrity of the complex 3D alginate hydrogel structure during the printing. The addition of 60 mM barium chloride was found to significantly extend the stability of the cross-linked alginate hydrogel from 3 d to beyond 11 d without compromising the cellular viability. The results based on cell bioprinting suggested that viability of U87-MG cells was 93 ± 0.9% immediately after bioprinting and cell viability maintained above 88% ± 4.3% in the alginate hydrogel over the period of 11 d. PMID:26689257

  18. Engineering alginate as bioink for bioprinting.

    PubMed

    Jia, Jia; Richards, Dylan J; Pollard, Samuel; Tan, Yu; Rodriguez, Joshua; Visconti, Richard P; Trusk, Thomas C; Yost, Michael J; Yao, Hai; Markwald, Roger R; Mei, Ying

    2014-10-01

    Recent advances in three-dimensional (3-D) printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been used extensively as bioinks for 3-D bioprinting. However, most previous research has focused on native alginates with limited degradation. The application of oxidized alginates with controlled degradation in bioprinting has not been explored. Here, a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations was prepared to develop a bioink platform that can be applied to a multitude of tissue engineering applications. The authors systematically investigated the effects of two key material properties (i.e. viscosity and density) of alginate solutions on their printabilities to identify a suitable range of material properties of alginates to be applied to bioprinting. Further, four alginate solutions with varied biodegradability were printed with human adipose-derived stem cells (hADSCs) into lattice-structured, cell-laden hydrogels with high accuracy. Notably, these alginate-based bioinks were shown to be capable of modulating proliferation and spreading of hADSCs without affecting the structure integrity of the lattice structures (except the highly degradable one) after 8days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications. PMID:24998183

  19. Engineering alginate as bioink for bioprinting

    PubMed Central

    Jia, Jia; Richards, Dylan J.; Pollard, Samuel; Tan, Yu; Rodriguez, Joshua; Visconti, Richard P.; Trusk, Thomas C.; Yost, Michael J.; Yao, Hai; Markwald, Roger R.; Mei, Ying

    2015-01-01

    Recent advances in 3D printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been extensively utilized as bioinks for 3D bioprinting. However, most previous research has focused on native alginates with limited degradation. The application of oxidized alginates with controlled degradation in bioprinting has not been explored. Here, we prepared a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations to develop a bioink platform that can be applied to a multitude of tissue engineering applications. We systematically investigated the effects of two key material properties (i.e. viscosity and density) of alginate solutions on their printabilities to identify a suitable range of material properties of alginates to be applied to bioprinting. Further, four alginate solutions with varied biodegradability were printed with human adipose-derived stem cells (hADSCs) into lattice-structured, cell-laden hydrogels with high accuracy. Notably, these alginate-based bioinks were shown to be capable of modulating proliferation and spreading of hADSCs without affecting structure integrity of the lattice structures (except the highly degradable one) after 8 days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications. PMID:24998183

  20. Biomimetic Scaffold with Aligned Microporosity Designed for Dentin Regeneration

    PubMed Central

    Panseri, Silvia; Montesi, Monica; Dozio, Samuele Maria; Savini, Elisa; Tampieri, Anna; Sandri, Monica

    2016-01-01

    Tooth loss is a common result of a variety of oral diseases due to physiological causes, trauma, genetic disorders, and aging and can lead to physical and mental suffering that markedly lowers the individual’s quality of life. Tooth is a complex organ that is composed of mineralized tissues and soft connective tissues. Dentin is the most voluminous tissue of the tooth and its formation (dentinogenesis) is a highly regulated process displaying several similarities with osteogenesis. In this study, gelatin, thermally denatured collagen, was used as a promising low-cost material to develop scaffolds for hard tissue engineering. We synthetized dentin-like scaffolds using gelatin biomineralized with magnesium-doped hydroxyapatite and blended it with alginate. With a controlled freeze-drying process and alginate cross-linking, it is possible to obtain scaffolds with microscopic aligned channels suitable for tissue engineering. 3D cell culture with mesenchymal stem cells showed the promising properties of the new scaffolds for tooth regeneration. In detail, the chemical–physical features of the scaffolds, mimicking those of natural tissue, facilitate the cell adhesion, and the porosity is suitable for long-term cell colonization and fine cell–material interactions. PMID:27376060

  1. Biomimetic Scaffold with Aligned Microporosity Designed for Dentin Regeneration.

    PubMed

    Panseri, Silvia; Montesi, Monica; Dozio, Samuele Maria; Savini, Elisa; Tampieri, Anna; Sandri, Monica

    2016-01-01

    Tooth loss is a common result of a variety of oral diseases due to physiological causes, trauma, genetic disorders, and aging and can lead to physical and mental suffering that markedly lowers the individual's quality of life. Tooth is a complex organ that is composed of mineralized tissues and soft connective tissues. Dentin is the most voluminous tissue of the tooth and its formation (dentinogenesis) is a highly regulated process displaying several similarities with osteogenesis. In this study, gelatin, thermally denatured collagen, was used as a promising low-cost material to develop scaffolds for hard tissue engineering. We synthetized dentin-like scaffolds using gelatin biomineralized with magnesium-doped hydroxyapatite and blended it with alginate. With a controlled freeze-drying process and alginate cross-linking, it is possible to obtain scaffolds with microscopic aligned channels suitable for tissue engineering. 3D cell culture with mesenchymal stem cells showed the promising properties of the new scaffolds for tooth regeneration. In detail, the chemical-physical features of the scaffolds, mimicking those of natural tissue, facilitate the cell adhesion, and the porosity is suitable for long-term cell colonization and fine cell-material interactions. PMID:27376060

  2. 3D Printing Facilitated Scaffold-free Tissue Unit Fabrication

    PubMed Central

    Tan, Yu; Richards, Dylan J.; Trusk, Thomas C.; Visconti, Richard P.; Yost, Michael J.; Kindy, Mark S.; Drake, Christopher J.; Argraves, William Scott; Markwald, Roger R.; Mei, Ying

    2014-01-01

    Tissue spheroids hold great potential in tissue engineering as building blocks to assemble into functional tissues. To date, agarose molds have been extensively used to facilitate fusion process of tissue spheroids. As a molding material, agarose typically requires low temperature plates for gelation and/or heated dispenser units. Here, we proposed and developed an alginate-based, direct 3D mold-printing technology: 3D printing micro-droplets of alginate solution into biocompatible, bio-inert alginate hydrogel molds for the fabrication of scaffold-free tissue engineering constructs. Specifically, we developed a 3D printing technology to deposit micro-droplets of alginate solution on calcium containing substrates in a layer-by-layer fashion to prepare ring-shaped 3D hydrogel molds. Tissue spheroids composed of 50% endothelial cells and 50% smooth muscle cells were robotically placed into the 3D printed alginate molds using a 3D printer, and were found to rapidly fuse into toroid-shaped tissue units. Histological and immunofluorescence analysis indicated that the cells secreted collagen type I playing a critical role in promoting cell-cell adhesion, tissue formation and maturation. PMID:24717646

  3. 3D printing facilitated scaffold-free tissue unit fabrication.

    PubMed

    Tan, Yu; Richards, Dylan J; Trusk, Thomas C; Visconti, Richard P; Yost, Michael J; Kindy, Mark S; Drake, Christopher J; Argraves, William Scott; Markwald, Roger R; Mei, Ying

    2014-06-01

    Tissue spheroids hold great potential in tissue engineering as building blocks to assemble into functional tissues. To date, agarose molds have been extensively used to facilitate fusion process of tissue spheroids. As a molding material, agarose typically requires low temperature plates for gelation and/or heated dispenser units. Here, we proposed and developed an alginate-based, direct 3D mold-printing technology: 3D printing microdroplets of alginate solution into biocompatible, bio-inert alginate hydrogel molds for the fabrication of scaffold-free tissue engineering constructs. Specifically, we developed a 3D printing technology to deposit microdroplets of alginate solution on calcium containing substrates in a layer-by-layer fashion to prepare ring-shaped 3D hydrogel molds. Tissue spheroids composed of 50% endothelial cells and 50% smooth muscle cells were robotically placed into the 3D printed alginate molds using a 3D printer, and were found to rapidly fuse into toroid-shaped tissue units. Histological and immunofluorescence analysis indicated that the cells secreted collagen type I playing a critical role in promoting cell-cell adhesion, tissue formation and maturation. PMID:24717646

  4. Alginate cryogel based glucose biosensor

    NASA Astrophysics Data System (ADS)

    Fatoni, Amin; Windy Dwiasi, Dian; Hermawan, Dadan

    2016-02-01

    Cryogel is macroporous structure provides a large surface area for biomolecule immobilization. In this work, an alginate cryogel based biosensor was developed to detect glucose. The cryogel was prepared using alginate cross-linked by calcium chloride under sub-zero temperature. This porous structure was growth in a 100 μL micropipette tip with a glucose oxidase enzyme entrapped inside the cryogel. The glucose detection was based on the colour change of redox indicator, potassium permanganate, by the hydrogen peroxide resulted from the conversion of glucose. The result showed a porous structure of alginate cryogel with pores diameter of 20-50 μm. The developed glucose biosensor was showed a linear response in the glucose detection from 1.0 to 5.0 mM with a regression of y = 0.01x+0.02 and R2 of 0.994. Furthermore, the glucose biosensor was showed a high operational stability up to 10 times of uninterrupted glucose detections.

  5. Deterioration of polyamino acid-coated alginate microcapsules in vivo.

    PubMed

    van Raamsdonk, J M; Cornelius, R M; Brash, J L; Chang, P L

    2002-01-01

    The implantation of immuno-isolated recombinant cell lines secreting a therapeutic protein in alginate microcapsules presents an alternative approach to gene therapy. Its clinical efficacy has recently been demonstrated in treating several genetic diseases in murine models. However, its application to humans will depend on the long-term structural stability of the microcapsules. Based on previous implantations in canines, it appears that survival of alginate-poly-L-lysine-alginate microcapsules in such large animals is short-lived. This article reports on the biological factors that may have contributed to the degradation of these microcapsules after implantation in dogs. Alginate microcapsules coated with poly-L-lysine or poly-L-arginine were implanted in subcutaneous or intraperitoneal sites. The retrieved microcapsules showed a loss of mechanical stability, as measured by resistance to osmotic stress. The polyamino acid coats were rendered fragile and easily lost, particularly when poly-L-lysine was used for coating and the intraperitoneal site was used for implantation. Various plasma proteins were associated with the retrieved microcapsules and identified with western blotting to include Factor XI, Factor XII, prekallikrein, HMWK, fibrinogen, plasminogen, ATIII, transferrin, alpha-1-antitrypsin, fibronectin, IgG, alpha-2-macroglobulin, vitronectin, prothrombin, apolipoprotein A1, and particularly albumin, a major Ca-transporting plasma protein. Complement proteins (C3, Factor B, Factor H, Factor I) and C3 activation fragments were detected. Release of the amino acids from the microcapsule polyamino acid coats was observed after incubation with plasma. indicating the occurrence of proteolytic degradation. Hence, the loss of long-term stability of the polyamino acid-coated alginate microcapsules is associated with activation of the complement system, degradation of the polyamino acid coating, and destabilization of the alginate core matrix, probably through loss

  6. Physicochemical characterization and biocompatibility of alginate-polycation microcapsules designed for islet transplantation

    NASA Astrophysics Data System (ADS)

    Tam, Susan Kimberly

    diabetic mice. To achieve these aims, extensive physicochemical analyses of the alginates and microcapsules were carried out. Among the properties of the alginates that were investigated include their purity (LAL assay, microBCA), chemical composition (nuclear magnetic resonance, NMR), elemental composition (x-ray photoelectron spectroscopy, XPS), and hydrophilicity (contact angle technique). As for the microcapsules, we also examined their surface chemical composition (XPS), hydrophilicity, as well as alginate-polycation interactions (Fourier transform infrared spectroscopy, FTIR), and membrane strength (osmotic swelling). The results of this research led to a number of important conclusions about the biocompatibility of alginates and alginate-based microcapsules. First of all, purifying an alginate does not guarantee its biocompatibility. Indeed, we provided evidence that both the alginate chemical composition (i.e. relative content of mannuronate and guluronate) and its intrinsic viscosity influence the extent of host cell adhesion to alginate gel beads. Using a biocompatible alginate, we then provided evidence that microcapsule biocompatibility is greatly compromised by its polycationic membrane. We showed that this membrane is responsible for the adsorption of opsonizing proteins in vitro and the adhesion of immune cells in vivo. That said, the severity of inflammatory response to the membrane can vary, and this depended on the microcapsule design, including the choice of alginate and polycation type. Results of our physicochemical analyses suggested that the most important factor determining biocompatibility is the ability of the polycation to diffuse into, and subsequently bind to, the alginate gel core. Moreover, adding a final coating of alginate had no significant effect on reversing the effects of the membrane on various microcapsule properties (surface composition, hydrophobicity, stability), nor did this coating reduce its immunogenicity. Although we

  7. Characterization of alginate lyase activity on liquid, gelled, and complexed states of alginate.

    PubMed

    Breguet, Véronique; von Stockar, Urs; Marison, Ian W

    2007-01-01

    A study of alginate lyase was carried out to determine if this enzyme could be used to remove alginate present in the core of alginate/poly-L-lysine (AG/PLL) microcapsules in order to maximize cell growth and colonization. A complete kinetic study was undertaken, which indicated an optimal activity of the enzyme at pH 7-8, 50 degrees C, in the presence of Ca2+. The buffer, not the ionic strength, influenced the alginate degradation rate. Alginate lyase was also shown to be active on gelled forms of alginate, as well as on the AG/PLL complex constituting the membrane of microcapsules. Batch cultures of CHO cells in the presence of alginate showed a decrease of the growth rate by a factor of 2, although the main metabolic flux rates were not modified. The addition of alginate lyase to cell culture medium increased the doubling time 5-7-fold and decreased the protein production rate, although cell viability was not affected. The addition of enzyme to medium containing alginate did not improve growth conditions. This suggests that alginate lyase is probably not suitable for hydrolysis of microcapsules in the presence of cells, in order to achieve high cell density and high productivity. However, the high activity may be useful for releasing cells from alginate beads or AG/PLL microcapsules. PMID:17691813

  8. Electrodeposition of alginate/chitosan layer-by-layer composite coatings on titanium substrates.

    PubMed

    Wang, Zhiliang; Zhang, Xueqin; Gu, Juming; Yang, Haitao; Nie, Jun; Ma, Guiping

    2014-03-15

    In this study, alginate/chitosan layer-by-layer composite coatings were prepared on titanium substrates via electrodeposition. The mechanism of anodic deposition of anionic alginate based on the pH decrease at the anode surface, while the pH increase at the cathode surface enabled the deposition of cationic chitosan coatings. The surface of coatings was characterized by using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The properties of coatings were characterized by X-ray diffraction (XRD) and differential thermal analysis (DTA). Indirect in vitro cytotoxicity test showed that the extracts of coating had no significant effects on cell viability. Moreover, in vitro cytocompatibility test exhibited cell population and spreading tendency, suggesting that the coatings were non-toxic to L929 cells. However, the results revealed that alginate coating was more benefit for cells growing than chitosan coating. The results indicated that the proposed method could be used to fabricate alginate/chitosan layer-by-layer composite coatings on the titanium surface at room temperature and such composite coatings might have potential applications in tissue engineering scaffolds field. PMID:24528698

  9. Alginate/Poly(γ-glutamic Acid) Base Biocompatible Gel for Bone Tissue Engineering

    PubMed Central

    Chan, Wing P.; Kung, Fu-Chen; Kuo, Yu-Lin; Yang, Ming-Chen; Lai, Wen-Fu Thomas

    2015-01-01

    A technique for synthesizing biocompatible hydrogels by cross-linking calcium-form poly(γ-glutamic acid), alginate sodium, and Pluronic F-127 was created, in which alginate can be cross-linked by Ca2+ from Ca–γ-PGA directly and γ-PGA molecules introduced into the alginate matrix to provide pH sensitivity and hemostasis. Mechanical properties, swelling behavior, and blood compatibility were investigated for each hydrogel compared with alginate and for γ-PGA hydrogel with the sodium form only. Adding F-127 improves mechanical properties efficiently and influences the temperature-sensitive swelling of the hydrogels but also has a minor effect on pH-sensitive swelling and promotes anticoagulation. MG-63 cells were used to test biocompatibility. Gelation occurred gradually through change in the elastic modulus as the release of calcium ions increased over time and caused ionic cross-linking, which promotes the elasticity of gel. In addition, the growth of MG-63 cells in the gel reflected nontoxicity. These results showed that this biocompatible scaffold has potential for application in bone materials. PMID:26504784

  10. Alginate/Poly(γ-glutamic Acid) Base Biocompatible Gel for Bone Tissue Engineering.

    PubMed

    Chan, Wing P; Kung, Fu-Chen; Kuo, Yu-Lin; Yang, Ming-Chen; Lai, Wen-Fu Thomas

    2015-01-01

    A technique for synthesizing biocompatible hydrogels by cross-linking calcium-form poly(γ-glutamic acid), alginate sodium, and Pluronic F-127 was created, in which alginate can be cross-linked by Ca(2+) from Ca-γ-PGA directly and γ-PGA molecules introduced into the alginate matrix to provide pH sensitivity and hemostasis. Mechanical properties, swelling behavior, and blood compatibility were investigated for each hydrogel compared with alginate and for γ-PGA hydrogel with the sodium form only. Adding F-127 improves mechanical properties efficiently and influences the temperature-sensitive swelling of the hydrogels but also has a minor effect on pH-sensitive swelling and promotes anticoagulation. MG-63 cells were used to test biocompatibility. Gelation occurred gradually through change in the elastic modulus as the release of calcium ions increased over time and caused ionic cross-linking, which promotes the elasticity of gel. In addition, the growth of MG-63 cells in the gel reflected nontoxicity. These results showed that this biocompatible scaffold has potential for application in bone materials. PMID:26504784

  11. Alginate Biosynthesis Factories in Pseudomonas fluorescens: Localization and Correlation with Alginate Production Level

    PubMed Central

    Maleki, Susan; Almaas, Eivind; Zotchev, Sergey; Valla, Svein

    2015-01-01

    Pseudomonas fluorescens is able to produce the medically and industrially important exopolysaccharide alginate. The proteins involved in alginate biosynthesis and secretion form a multiprotein complex spanning the inner and outer membranes. In the present study, we developed a method by which the porin AlgE was detected by immunogold labeling and transmission electron microscopy. Localization of the AlgE protein was found to depend on the presence of other proteins in the multiprotein complex. No correlation was found between the number of alginate factories and the alginate production level, nor were the numbers of these factories affected in an algC mutant that is unable to produce the precursor needed for alginate biosynthesis. Precursor availability and growth phase thus seem to be the main determinants for the alginate production rate in our strain. Clustering analysis demonstrated that the alginate multiprotein complexes were not distributed randomly over the entire outer cell membrane surface. PMID:26655760

  12. Alginate Biosynthesis Factories in Pseudomonas fluorescens: Localization and Correlation with Alginate Production Level.

    PubMed

    Maleki, Susan; Almaas, Eivind; Zotchev, Sergey; Valla, Svein; Ertesvåg, Helga

    2016-02-01

    Pseudomonas fluorescens is able to produce the medically and industrially important exopolysaccharide alginate. The proteins involved in alginate biosynthesis and secretion form a multiprotein complex spanning the inner and outer membranes. In the present study, we developed a method by which the porin AlgE was detected by immunogold labeling and transmission electron microscopy. Localization of the AlgE protein was found to depend on the presence of other proteins in the multiprotein complex. No correlation was found between the number of alginate factories and the alginate production level, nor were the numbers of these factories affected in an algC mutant that is unable to produce the precursor needed for alginate biosynthesis. Precursor availability and growth phase thus seem to be the main determinants for the alginate production rate in our strain. Clustering analysis demonstrated that the alginate multiprotein complexes were not distributed randomly over the entire outer cell membrane surface. PMID:26655760

  13. Alginate lyase: Review of major sources and classification, properties, structure-function analysis and applications

    PubMed Central

    Zhu, Benwei; Yin, Heng

    2015-01-01

    Alginate lyases catalyze the degradation of alginate, a complex copolymer of α-L-guluronate and its C5 epimer β-D-mannuronate. The enzymes have been isolated from various kinds of organisms with different substrate specificities, including algae, marine mollusks, marine and terrestrial bacteria, and some viruses and fungi. With the progress of structural biology, many kinds of alginate lyases of different polysaccharide lyases families have been characterized by obtaining crystal structures, and the catalytic mechanism has also been elucidated. Combined with various studies, we summarized the source, classification and properties of the alginate lyases from different polysaccharide lyases families. The relationship between substrate specificity and protein sequence was also investigated. PMID:25831216

  14. Development of an angiogenesis-promoting microvesicle-alginate-polycaprolactone composite graft for bone tissue engineering applications.

    PubMed

    Xie, Hui; Wang, Zhenxing; Zhang, Liming; Lei, Qian; Zhao, Aiqi; Wang, Hongxiang; Li, Qiubai; Chen, Zhichao; Zhang, WenJie

    2016-01-01

    One of the major challenges of bone tissue engineering applications is to construct a fully vascularized implant that can adapt to hypoxic environments in vivo. The incorporation of proangiogenic factors into scaffolds is a widely accepted method of achieving this goal. Recently, the proangiogenic potential of mesenchymal stem cell-derived microvesicles (MSC-MVs) has been confirmed in several studies. In the present study, we incorporated MSC-MVs into alginate-polycaprolactone (PCL) constructs that had previously been developed for bone tissue engineering applications, with the aim of promoting angiogenesis and bone regeneration. MSC-MVs were first isolated from the supernatant of rat bone marrow-derived MSCs and characterized by scanning electron microscopic, confocal microscopic, and flow cytometric analyses. The proangiogenic potential of MSC-MVs was demonstrated by the stimulation of tube formation of human umbilical vein endothelial cells in vitro. MSC-MVs and osteodifferentiated MSCs were then encapsulated with alginate and seeded onto porous three-dimensional printed PCL scaffolds. When combined with osteodifferentiated MSCs, the MV-alginate-PCL constructs enhanced vessel formation and tissue-engineered bone regeneration in a nude mouse subcutaneous bone formation model, as demonstrated by micro-computed tomographic, histological, and immunohistochemical analyses. This MV-alginate-PCL construct may offer a novel, proangiogenic, and cost-effective option for bone tissue engineering. PMID:27231660

  15. Development of an angiogenesis-promoting microvesicle-alginate-polycaprolactone composite graft for bone tissue engineering applications

    PubMed Central

    Zhang, Liming; Lei, Qian; Zhao, Aiqi; Wang, Hongxiang; Li, Qiubai

    2016-01-01

    One of the major challenges of bone tissue engineering applications is to construct a fully vascularized implant that can adapt to hypoxic environments in vivo. The incorporation of proangiogenic factors into scaffolds is a widely accepted method of achieving this goal. Recently, the proangiogenic potential of mesenchymal stem cell-derived microvesicles (MSC-MVs) has been confirmed in several studies. In the present study, we incorporated MSC-MVs into alginate-polycaprolactone (PCL) constructs that had previously been developed for bone tissue engineering applications, with the aim of promoting angiogenesis and bone regeneration. MSC-MVs were first isolated from the supernatant of rat bone marrow-derived MSCs and characterized by scanning electron microscopic, confocal microscopic, and flow cytometric analyses. The proangiogenic potential of MSC-MVs was demonstrated by the stimulation of tube formation of human umbilical vein endothelial cells in vitro. MSC-MVs and osteodifferentiated MSCs were then encapsulated with alginate and seeded onto porous three-dimensional printed PCL scaffolds. When combined with osteodifferentiated MSCs, the MV-alginate-PCL constructs enhanced vessel formation and tissue-engineered bone regeneration in a nude mouse subcutaneous bone formation model, as demonstrated by micro-computed tomographic, histological, and immunohistochemical analyses. This MV-alginate-PCL construct may offer a novel, proangiogenic, and cost-effective option for bone tissue engineering. PMID:27231660

  16. Multilayered Short Peptide-Alginate Blends as New Materials for Potential Applications in Cartilage Tissue Regeneration.

    PubMed

    Knoll, Grant A; Romanelli, Steven M; Brown, Alexandra M; Sortino, Rachel M; Banerjee, Ipsita A

    2016-03-01

    Peptide based nanomaterials have been gaining increased prominence due to their ability to form permeable scaffolds that promote growth and regeneration of new tissue. In this work for the first time a short hexapeptide motif VQIVYK, derived from the Tau protein family was conjugated with an organic polyamine linker, putrescine and utilized as a template for developing new materials for cartilage tissue regeneration. Our results showed that the conjugate formed extensive nanofibrous assemblies upon self-assembly under aqueous conditions. We then employed the layer-by-layer (LBL) approach to design the scaffold by first incorporating a short segment of the dentin sialophosphoprotein motif GDASYNSDESK followed by integration with the peptide sequence GSGAGAGSGAGAGSGAGA. This sequence mimics Ala, Gly, Ser repeats seen in the spider silk protein. We then incorporated the polysaccharide alginate which served as a hydrogel. To further enhance binding interactions with chondrocytes, and promote the formation of cartilage in vitro, the bionanocomposites were then attached to the chondrocyte binding peptide sequence HDSQLEALIKFM. The thermal properties as well as biodegradability of the scaffold was examined. To confirm biocompatibility, we examined cell viability, attachment and morphology in the presence of bovine chondrocytes. The cells were found to efficiently adhere to the scaffolds which formed an intricate mesh mimicking the extracellular matrix of cartilage tissue. To evaluate if differentiation occurred in the presence of the scaffolds, we examined in vitro deposition of proteoglycans. Thus, we have developed a new family of nanoscale scaffolds that may be utilized for cartilage tissue regeneration. PMID:27455656

  17. Dual delivery of BMP-2 and bFGF from a new nano-composite scaffold, loaded with vascular stents for large-size mandibular defect regeneration.

    PubMed

    Su, Jiansheng; Xu, Hongzhen; Sun, Jun; Gong, Xue; Zhao, Hang

    2013-01-01

    The aim of this study was to investigate the feasibility and advantages of the dual delivery of bone morphogenetic protein-2 (BMP-2) and basic fibroblast growth factor (bFGF) from nano-composite scaffolds (PLGA/PCL/nHA) loaded with vascular stents (PLCL/Col/nHA) for large bone defect regeneration in rabbit mandibles. Thirty-six large bone defects were repaired in rabbits using engineering bone composed of allogeneic bone marrow mesenchymal stem cells (BMSCs), bFGF, BMP-2 and scaffolds composed of PLGA/PCL/nHA loaded with PLCL/Col/nHA. The experiments were divided into six groups: BMSCs/bFGF/BMP-2/scaffold, BMSCs/BMP-2/scaffold, BMSCs/bFGF/scaffold, BMSCs/scaffold, scaffold alone and no treatment. Sodium alginate hydrogel was used as the carrier for BMP-2 and bFGF and its features, including gelling, degradation and controlled release properties, was detected by the determination of gelation and degradation time coupled with a controlled release study of bovine serum albumin (BSA). AlamarBlue assay and alkaline phosphatase (ALP) activity were used to evaluate the proliferation and osteogenic differentiation of BMSCs in different groups. X-ray and histological examinations of the samples were performed after 4 and 12 weeks post-implantation to clarify new bone formation in the mandible defects. The results verified that the use of sodium alginate hydrogel as a controlled release carrier has good sustained release ability, and the combined application of bFGF and BMP-2 could significantly promote the proliferation and osteogenic differentiation of BMSCs (p < 0.05 or p < 0.01). In addition, X-ray and histological examinations of the samples exhibited that the dual release group had significantly higher bone formation than the other groups. The above results indicate that the delivery of both growth factors could enhance new bone formation and vascularization compared with delivery of BMP-2 or bFGF alone, and may supply a promising way of repairing large bone defects in

  18. Physicochemical characterization and biocompatibility of alginate-polycation microcapsules designed for islet transplantation

    NASA Astrophysics Data System (ADS)

    Tam, Susan Kimberly

    diabetic mice. To achieve these aims, extensive physicochemical analyses of the alginates and microcapsules were carried out. Among the properties of the alginates that were investigated include their purity (LAL assay, microBCA), chemical composition (nuclear magnetic resonance, NMR), elemental composition (x-ray photoelectron spectroscopy, XPS), and hydrophilicity (contact angle technique). As for the microcapsules, we also examined their surface chemical composition (XPS), hydrophilicity, as well as alginate-polycation interactions (Fourier transform infrared spectroscopy, FTIR), and membrane strength (osmotic swelling). The results of this research led to a number of important conclusions about the biocompatibility of alginates and alginate-based microcapsules. First of all, purifying an alginate does not guarantee its biocompatibility. Indeed, we provided evidence that both the alginate chemical composition (i.e. relative content of mannuronate and guluronate) and its intrinsic viscosity influence the extent of host cell adhesion to alginate gel beads. Using a biocompatible alginate, we then provided evidence that microcapsule biocompatibility is greatly compromised by its polycationic membrane. We showed that this membrane is responsible for the adsorption of opsonizing proteins in vitro and the adhesion of immune cells in vivo. That said, the severity of inflammatory response to the membrane can vary, and this depended on the microcapsule design, including the choice of alginate and polycation type. Results of our physicochemical analyses suggested that the most important factor determining biocompatibility is the ability of the polycation to diffuse into, and subsequently bind to, the alginate gel core. Moreover, adding a final coating of alginate had no significant effect on reversing the effects of the membrane on various microcapsule properties (surface composition, hydrophobicity, stability), nor did this coating reduce its immunogenicity. Although we

  19. Crystal structure of bacterial cell-surface alginate-binding protein with an M75 peptidase motif

    SciTech Connect

    Maruyama, Yukie; Ochiai, Akihito; Mikami, Bunzo; Hashimoto, Wataru; Murata, Kousaku

    2011-02-18

    Research highlights: {yields} Bacterial alginate-binding Algp7 is similar to component EfeO of Fe{sup 2+} transporter. {yields} We determined the crystal structure of Algp7 with a metal-binding motif. {yields} Algp7 consists of two helical bundles formed through duplication of a single bundle. {yields} A deep cleft involved in alginate binding locates around the metal-binding site. {yields} Algp7 may function as a Fe{sup 2+}-chelated alginate-binding protein. -- Abstract: A gram-negative Sphingomonas sp. A1 directly incorporates alginate polysaccharide into the cytoplasm via the cell-surface pit and ABC transporter. A cell-surface alginate-binding protein, Algp7, functions as a concentrator of the polysaccharide in the pit. Based on the primary structure and genetic organization in the bacterial genome, Algp7 was found to be homologous to an M75 peptidase motif-containing EfeO, a component of a ferrous ion transporter. Despite the presence of an M75 peptidase motif with high similarity, the Algp7 protein purified from recombinant Escherichia coli cells was inert on insulin B chain and N-benzoyl-Phe-Val-Arg-p-nitroanilide, both of which are substrates for a typical M75 peptidase, imelysin, from Pseudomonas aeruginosa. The X-ray crystallographic structure of Algp7 was determined at 2.10 A resolution by single-wavelength anomalous diffraction. Although a metal-binding motif, HxxE, conserved in zinc ion-dependent M75 peptidases is also found in Algp7, the crystal structure of Algp7 contains no metal even at the motif. The protein consists of two structurally similar up-and-down helical bundles as the basic scaffold. A deep cleft between the bundles is sufficiently large to accommodate macromolecules such as alginate polysaccharide. This is the first structural report on a bacterial cell-surface alginate-binding protein with an M75 peptidase motif.

  20. Electrospun multifunctional tissue engineering scaffolds

    NASA Astrophysics Data System (ADS)

    Wang, Chong; Wang, Min

    2014-03-01

    Tissue engineering holds great promises in providing successful treatments of human body tissue loss that current methods are unable to treat or unable to achieve satisfactory clinical outcomes. In scaffold-based tissue engineering, a highperformance scaffold underpins the success of a tissue engineering strategy and a major direction in the field is to create multifunctional tissue engineering scaffolds for enhanced biological performance and for regenerating complex body tissues. Electrospinning can produce nanofibrous scaffolds that are highly desirable for tissue engineering. The enormous interest in electrospinning and electrospun fibrous structures by the science, engineering and medical communities has led to various developments of the electrospinning technology and wide investigations of electrospun products in many industries, including biomedical engineering, over the past two decades. It is now possible to create novel, multicomponent tissue engineering scaffolds with multiple functions. This article provides a concise review of recent advances in the R & D of electrospun multifunctional tissue engineering scaffolds. It also presents our philosophy and research in the designing and fabrication of electrospun multicomponent scaffolds with multiple functions.

  1. An alginate-like exopolysaccharide biosynthesis gene cluster involved in biofilm aerial structure formation by Pseudomonas alkylphenolia.

    PubMed

    Lee, Kyoung; Lim, Eun Jin; Kim, Keun Soo; Huang, Shir-Ly; Veeranagouda, Yaligara; Rehm, Bernd H A

    2014-05-01

    Pseudomonas alkylphenolia is known to form different types of multicellular structures depending on the environmental stimuli. Aerial structures formed during vapor p-cresol utilization are unique. Transposon mutants that showed a smooth colony phenotype failed to form a differentiated biofilm, including aerial structures and pellicles, and showed deficient surface spreading motility. The transposon insertion sites were located to a gene cluster designated epm (extracellular polymer matrix), which comprises 11 ORFs in the same transcriptional orientation. The putative proteins encoded by the genes in the epm cluster showed amino acid sequence homology to those found in the alginate biosynthesis gene clusters, e.g., in Pseudomonas aeruginosa at similarity levels of 32.3-86.4 %. This overall resemblance indicated that the epm gene cluster encodes proteins that mediate the synthesis of an exopolysaccharide composed of uronic acid(s) similar to alginate. Our preliminary results suggested that the epm-derived polymer is a substituted polymannuronic acid. Gene clusters homologous to the epm gene cluster are found in the genomes of a few species of the genera Pseudomonas, Alcanivorax, and Marinobacter. A mutational analysis showed that the epmJ and epmG genes encoding putative exopolysaccharide-modifying enzymes are required to form multicellular structures. An analysis of the activity of the promoter P epmD using a transcriptional fusion to the green fluorescence protein gene showed that the epm genes are strongly expressed at the tips of the specialized aerial structures. Our results suggested that the epm gene cluster is involved in the formation of a scaffold polysaccharide that is required to form multicellular structures in P. alkylphenolia. PMID:24493568

  2. Delivering MC3T3-E1 cells into injectable calcium phosphate cement through alginate-chitosan microcapsules for bone tissue engineering*

    PubMed Central

    Qiao, Peng-yan; Li, Fang-fang; Dong, Li-min; Xu, Tao; Xie, Qiu-fei

    2014-01-01

    Objective: To deliver cells deep into injectable calcium phosphate cement (CPC) through alginate-chitosan (AC) microcapsules and investigate the biological behavior of the cells released from microcapsules into the CPC. Methods: Mouse osteoblastic MC3T3-E1 cells were embedded in alginate and AC microcapsules using an electrostatic droplet generator. The two types of cell-encapsulating microcapsules were then mixed with a CPC paste. MC3T3-E1 cell viability was investigated using a Wst-8 kit, and osteogenic differentiation was demonstrated by an alkaline phosphatase (ALP) activity assay. Cell attachment in CPC was observed by an environment scanning electron microscopy. Results: Both alginate and AC microcapsules were able to release the encapsulated MC3T3-E1 cells when mixed with CPC paste. The released cells attached to the setting CPC scaffolds, survived, differentiated, and formed mineralized nodules. Cells grew in the pores concomitantly created by the AC microcapsules in situ within the CPC. At Day 21, cellular ALP activity in the AC group was approximately four times that at Day 7 and exceeded that of the alginate microcapsule group (P<0.05). Pores formed by the AC microcapsules had a diameter of several hundred microns and were spherical compared with those formed by alginate microcapsules. Conclusions: AC microcapsule is a promising carrier to release seeding cells deep into an injectable CPC scaffold for bone engineering. PMID:24711359

  3. Alginate-modifying enzymes: biological roles and biotechnological uses

    PubMed Central

    Ertesvåg, Helga

    2015-01-01

    Alginate denotes a group of industrially important 1-4-linked biopolymers composed of the C-5-epimers β-D-mannuronic acid (M) and α-L-guluronic acid (G). The polysaccharide is manufactured from brown algae where it constitutes the main structural cell wall polymer. The physical properties of a given alginate molecule, e.g., gel-strength, water-binding capacity, viscosity and biocompatibility, are determined by polymer length, the relative amount and distribution of G residues and the acetyl content, all of which are controlled by alginate modifying enzymes. Alginate has also been isolated from some bacteria belonging to the genera Pseudomonas and Azotobacter, and bacterially synthesized alginate may be O-acetylated at O-2 and/or O-3. Initially, alginate is synthesized as polymannuronic acid, and some M residues are subsequently epimerized to G residues. In bacteria a mannuronan C-5-epimerase (AlgG) and an alginate acetylase (AlgX) are integral parts of the protein complex necessary for alginate polymerization and export. All alginate-producing bacteria use periplasmic alginate lyases to remove alginate molecules aberrantly released to the periplasm. Alginate lyases are also produced by organisms that utilize alginate as carbon source. Most alginate-producing organisms encode more than one mannuronan C-5 epimerase, each introducing its specific pattern of G residues. Acetylation protects against further epimerization and from most alginate lyases. An enzyme from Pseudomonas syringae with alginate deacetylase activity has been reported. Functional and structural studies reveal that alginate lyases and epimerases have related enzyme mechanisms and catalytic sites. Alginate lyases are now utilized as tools for alginate characterization. Secreted epimerases have been shown to function well in vitro, and have been engineered further in order to obtain enzymes that can provide alginates with new and desired properties for use in medical and pharmaceutical applications

  4. Performance evaluation of bipolar and tripolar excitations during nozzle-jetting-based alginate microsphere fabrication

    NASA Astrophysics Data System (ADS)

    Herran, C. Leigh; Huang, Yong; Chai, Wenxuan

    2012-08-01

    Microspheres, small spherical (polymeric) particles with or without second phase materials embedded or encapsulated, are important for many biomedical applications such as drug delivery and organ printing. Scale-up fabrication with the ability to precisely control the microsphere size and morphology has always been of great manufacturing interest. The objective of this work is to experimentally study the performance differences of bipolar and tripolar excitation waveforms in using drop-on-demand (DOD)-based single nozzle jetting for alginate microsphere fabrication. The fabrication performance has been evaluated based on the formability of alginate microspheres as a function of materials properties (sodium alginate and calcium chloride concentrations) and operating conditions. The operating conditions for each excitation include voltage rise/fall times, dwell times and excitation voltage amplitudes. Overall, the bipolar excitation is more robust in making spherical, monodispersed alginate microspheres as good microspheres for its wide working range of material properties and operating conditions, especially during the fabrication of highly viscous materials such as the 2% sodium alginate solution. For both bipolar and tripolar excitations, the sodium alginate concentration and the voltage dwell times should be carefully selected to achieve good microsphere formability.

  5. Preparation of regular sized Ca-alginate microspheres using membrane emulsification method.

    PubMed

    You, J O; Park, S B; Park, H Y; Haam, S; Chung, C H; Kim, W S

    2001-01-01

    Monodisperse Ca-alginate microspheres were prepared using the membrane emulsification method. Three ionic types of drugs (anionic, cationic and non-ionic) were incorporated into the microspheres, and the effects of sodium alginate concentration and the pressure applied during the dispersing process on the properties of the microspheres were examined. Monodisperse microspheres were obtained when the concentration of alginate solution was 2 wt% and the pressure applied was 0.4 x 10(5) Pa. The mean size of microspheres was approximately 4 microm. Lidocaine x HCl (cationic), sodium salicylate (anionic) and 4-acetamidophenol (non-ionic) were selected as ionic model drugs and included in the alginate microspheres. Lidocaine x HCl (cationic drug) release was more retarded than that of the anionic drug, because of the electrostatic attraction between the negative charge of the ionized carboxyl group in the alginate chain and the positive charge of the cationic drug. In acidic release medium, a slow release was observed due to the low swelling characteristic and the increased viscosity of alginate, regardless of ionic type of drug. PMID:11428680

  6. Influence of amino acids, buffers, and ph on the γ-irradiation-induced degradation of alginates.

    PubMed

    Ulset, Ann-Sissel T; Mori, Hideki; Dalheim, Marianne Ø; Hara, Masayuki; Christensen, Bjørn E

    2014-12-01

    Alginate-based biomaterials and medical devices are commonly subjected to γ-irradiation as a means of sterilization, either in the dry state or the gel (hydrated) state. In this process the alginate chains degrade randomly in a dose-dependent manner, altering alginates' material properties. The addition of free radical scavenging amino acids such as histidine and phenylalanine protects the alginate significantly against degradation, as shown by monitoring changes in the molecular weight distributions using SEC-MALLS and determining the pseudo first order rate constants of degradation. Tris buffer (0.5 M), but not acetate, citrate, or phosphate buffers had a similar effect on the degradation rate. Changes in pH itself had only marginal effects on the rate of alginate degradation and on the protective effect of amino acids. Contrary to previous reports, the chemical composition (M/G profile) of the alginates, including homopolymeric mannuronan, was unaltered following irradiation up to 10 kGy. PMID:25412478

  7. Alginic Acid Accelerates Calcite Dissolution

    NASA Astrophysics Data System (ADS)

    Perry, T. D.; Duckworth, O. W.; McNamara, C. J.; Martin, S. T.; Mitchell, R.

    2003-12-01

    Accelerated carbonate weathering through biological activity affects both geochemical cycling and the local pH and alkalinity of terrestrial and marine waters. Microbes affect carbonate dissolution through metabolic activity, production of acidic or chelating exudates, and cation binding by cell walls. Dissolution occurs within microbial biofilms - communities of microorganisms attached to stone in an exopolymer matrix. We investigated the effect of alginic acid, a common biological polymer produced by bacteria and algae, on calcite dissolution using a paired atomic force microscopy/flow-through reactor apparatus. The alginic acid caused up to an order of magnitude increase in dissolution rate at 3 < pH < 12. Additionally, the polymer preferentially binds to the obtuse pit steps and increases step velocity. We propose that the polymer is actively chelating surficial cations reducing the activation energy and increasing dissolution rate. The role of biologically produced polymers in mineral weathering is important in the protection of cultural heritage materials and understanding of marine and terrestrial systems.

  8. Correlation between porous texture and cell seeding efficiency of gas foaming and microfluidic foaming scaffolds.

    PubMed

    Costantini, Marco; Colosi, Cristina; Mozetic, Pamela; Jaroszewicz, Jakub; Tosato, Alessia; Rainer, Alberto; Trombetta, Marcella; Święszkowski, Wojciech; Dentini, Mariella; Barbetta, Andrea

    2016-05-01

    In the design of scaffolds for tissue engineering applications, morphological parameters such as pore size, shape, and interconnectivity, as well as transport properties, should always be tailored in view of their clinical application. In this work, we demonstrate that a regular and ordered porous texture is fundamental to achieve an even cell distribution within the scaffold under perfusion seeding. To prove our hypothesis, two sets of alginate scaffolds were fabricated using two different technological approaches of the same method: gas-in-liquid foam templating. In the first one, foam was obtained by insufflating argon in a solution of alginate and a surfactant under stirring. In the second one, foam was generated inside a flow-focusing microfluidic device under highly controlled and reproducible conditions. As a result, in the former case the derived scaffold (GF) was characterized by polydispersed pores and interconnects, while in the latter (μFL), the porous structure was highly regular both with respect to the spatial arrangement of pores and interconnects and their monodispersity. Cell seeding within perfusion bioreactors of the two scaffolds revealed that cell population inside μFL scaffolds was quantitatively higher than in GF. Furthermore, seeding efficiency data for μFL samples were characterized by a lower standard deviation, indicating higher reproducibility among replicates. Finally, these results were validated by simulation of local flow velocity (CFD) inside the scaffolds proving that μFL was around one order of magnitude more permeable than GF. PMID:26952471

  9. Muscle Tissue Engineering Using Gingival Mesenchymal Stem Cells Encapsulated in Alginate Hydrogels Containing Multiple Growth Factors.

    PubMed

    Ansari, Sahar; Chen, Chider; Xu, Xingtian; Annabi, Nasim; Zadeh, Homayoun H; Wu, Benjamin M; Khademhosseini, Ali; Shi, Songtao; Moshaverinia, Alireza

    2016-06-01

    Repair and regeneration of muscle tissue following traumatic injuries or muscle diseases often presents a challenging clinical situation. If a significant amount of tissue is lost the native regenerative potential of skeletal muscle will not be able to grow to fill the defect site completely. Dental-derived mesenchymal stem cells (MSCs) in combination with appropriate scaffold material, present an advantageous alternative therapeutic option for muscle tissue engineering in comparison to current treatment modalities available. To date, there has been no report on application of gingival mesenchymal stem cells (GMSCs) in three-dimensional scaffolds for muscle tissue engineering. The objectives of the current study were to develop an injectable 3D RGD-coupled alginate scaffold with multiple growth factor delivery capacity for encapsulating GMSCs, and to evaluate the capacity of encapsulated GMSCs to differentiate into myogenic tissue in vitro and in vivo where encapsulated GMSCs were transplanted subcutaneously into immunocompromised mice. The results demonstrate that after 4 weeks of differentiation in vitro, GMSCs as well as the positive control human bone marrow mesenchymal stem cells (hBMMSCs) exhibited muscle cell-like morphology with high levels of mRNA expression for gene markers related to muscle regeneration (MyoD, Myf5, and MyoG) via qPCR measurement. Our quantitative PCR analyzes revealed that the stiffness of the RGD-coupled alginate regulates the myogenic differentiation of encapsulated GMSCs. Histological and immunohistochemical/fluorescence staining for protein markers specific for myogenic tissue confirmed muscle regeneration in subcutaneous transplantation in our in vivo animal model. GMSCs showed significantly greater capacity for myogenic regeneration in comparison to hBMMSCs (p < 0.05). Altogether, our findings confirmed that GMSCs encapsulated in RGD-modified alginate hydrogel with multiple growth factor delivery capacity is a promising

  10. Photonic monitoring of chitosan nanostructured alginate microcapsules for drug release

    NASA Astrophysics Data System (ADS)

    Khajuria, Deepak Kumar; Konnur, Manish C.; Vasireddi, Ramakrishna; Roy Mahapatra, D.

    2015-02-01

    By using a novel microfluidic set-up for drug screening applications, this study examines delivery of a novel risedronate based drug formulation for treatment of osteoporosis that was developed to overcome the usual shortcomings of risedronate, such as its low bioavailability and adverse gastric effects. Risedronate nanoparticles were prepared using muco-adhesive polymers such as chitosan as matrix for improving the intestinal cellular absorption of risedronate and also using a gastric-resistant polymer such as sodium alginate for reducing the gastric inflammation of risedronate. The in-vitro characteristics of the alginate encapsulated chitosan nanoparticles are investigated, including their stability, muco-adhesiveness, and Caco-2 cell permeability. Fluorescent markers are tagged with the polymers and their morphology within the microcapsules is imaged at various stages of drug release.

  11. Laser-assisted fabrication of highly viscous alginate microsphere

    NASA Astrophysics Data System (ADS)

    Lin, Yafu; Huang, Yong

    2011-04-01

    Encapsulated microspheres have been widely used in various biomedical applications. However, fabrication of encapsulated microspheres from highly viscous materials has always been a manufacturing challenge. The objective of this study is to explore a novel metallic foil-assisted laser-induced forward transfer (LIFT), a laser-assisted fabrication technique, to make encapsulated microspheres using high sodium alginate concentration solutions. The proposed four-layer approach includes a quartz disk, a sacrificial and adhesive layer, a metallic foil, and a transferred suspension layer. It is found that the proposed four-layer modified LIFT approach provides a promising fabrication technology for making of bead-encapsulated microspheres from highly viscous solutions. During the process, the microsphere only can be formed if the direct-writing height is larger than the critical direct-writing height; otherwise, tail structured droplets are formed; and the encapsulated microsphere diameter linearly increases with the laser fluence and decreases with the sodium alginate concentration.

  12. Preclinical evaluation of collagen type I scaffolds, including gelatin-collagen microparticles and loaded with a hydroglycolic Calendula officinalis extract in a lagomorph model of full-thickness skin wound.

    PubMed

    Millán, D; Jiménez, R A; Nieto, L E; Linero, I; Laverde, M; Fontanilla, M R

    2016-02-01

    Previously, we have developed collagen type I scaffolds including microparticles of gelatin-collagen type I (SGC) that are able to control the release of a hydroglycolic extract of the Calendula officinalis flower. The main goal of the present work was to carry out the preclinical evaluation of SGC alone or loaded with the C. officinalis extract (SGC-E) in a lagomorph model of full-thickness skin wound. A total of 39 rabbits were distributed in three groups, of 13 animals each. The first group was used to compare wound healing by secondary intention (control) with wound healing observed when wounds were grafted with SGC alone. Comparison of control wounds with wounds grafted with SGC-E was performed in the second group, and comparison of wounds grafted with SGC with wounds grafted with SGC-E was performed in the third group. Clinical follow-ups were carried in all animals after surgery, and histological and histomorphometric analyses were performed on tissues taken from the healed area and healthy surrounding tissue. Histological and histomorphometric results indicate that grafting of SGC alone favors wound healing and brings a better clinical outcome than grafting SGC-E. In vitro collagenase digestion data suggested that the association of the C. officinalis extract to SGC increased the SGC-E cross-linking, making it difficult to degrade and affecting its biocompatibility. PMID:26597789

  13. Lactococcus lactis release from calcium alginate beads.

    PubMed Central

    Champagne, C P; Gaudy, C; Poncelet, D; Neufeld, R J

    1992-01-01

    Cell release during milk fermentation by Lactococcus lactis immobilized in calcium alginate beads was examined. Numbers of free cells in the milk gradually increased from 1 x 10(6) to 3 x 10(7) CFU/ml upon successive reutilization of the beads. Rinsing the beads between fermentations did not influence the numbers of free cells in the milk. Cell release was not affected by initial cell density within the beads or by alginate concentration, although higher acidification rates were achieved with increased cell loading. Coating alginate beads with poly-L-lysine (PLL) did not significantly reduce the release of cells during five consecutive fermentations. A double coating of PLL and alginate reduced cell release by a factor of approximately 50. However, acidification of milk with beads having the PLL-alginate coating was slower than that with uncoated beads. Immersing the beads in ethanol to kill cells on the periphery reduced cell release, but acidification activity was maintained. Dipping the beads in aluminum nitrate or a hot CaCl2 solution was not as effective as dipping them in ethanol. Ethanol treatment or heating of the beads appears to be a promising method for maintaining acidification activity while minimizing viable cell release due to loosely entrapped cells near the surface of the alginate beads. PMID:1622208

  14. Freeze-thaw induced gelation of alginates.

    PubMed

    Zhao, Ying; Shen, Wei; Chen, Zhigang; Wu, Tao

    2016-09-01

    Adding divalent ions or lowering pH below the pKa values of alginate monomers are common ways in preparing alginate gels. Herein a new way of preparing alginate gels using freeze-thaw technique is described. Solvent crystallization during freezing drove the polymers to associate into certain structures that became the junction zones of hydrogels after thawing. It enabled the preparation of alginate gels at pH 4.0 and 3.5, two pH at which the gel could not be formed previously. At pH 3.0 where alginate gel could be formed initially, applying freeze-thaw treatment increased the gel storage modulus almost 100 times. The formation of hydrogels and the resulting gel properties, such as dynamic moduli and gel syneresis were influenced by the pH values, number of freeze-thaw cycles, alginate concentrations, and ionic strengths. The obtained hydrogels were soft and demonstrated a melting behavior upon storage, which may find novel applications in the biomedical industry. PMID:27185114

  15. Chromosome Scaffold is a Double-Stranded Assembly of Scaffold Proteins

    PubMed Central

    Poonperm, Rawin; Takata, Hideaki; Hamano, Tohru; Matsuda, Atsushi; Uchiyama, Susumu; Hiraoka, Yasushi; Fukui, Kiichi

    2015-01-01

    Chromosome higher order structure has been an enigma for over a century. The most important structural finding has been the presence of a chromosome scaffold composed of non-histone proteins; so-called scaffold proteins. However, the organization and function of the scaffold are still controversial. Here, we use three dimensional-structured illumination microscopy (3D-SIM) and focused ion beam/scanning electron microscopy (FIB/SEM) to reveal the axial distributions of scaffold proteins in metaphase chromosomes comprising two strands. We also find that scaffold protein can adaptably recover its original localization after chromosome reversion in the presence of cations. This reversion to the original morphology underscores the role of the scaffold for intrinsic structural integrity of chromosomes. We therefore propose a new structural model of the chromosome scaffold that includes twisted double strands, consistent with the physical properties of chromosomal bending flexibility and rigidity. Our model provides new insights into chromosome higher order structure. PMID:26132639

  16. Preparation, modification, and characterization of alginate hydrogel with nano-/microfibers: a new perspective for tissue engineering.

    PubMed

    Santana, Bianca Palma; Nedel, Fernanda; Piva, Evandro; de Carvalho, Rodrigo Varella; Demarco, Flávio Fernando; Carreño, Neftali Lenin Villarreal

    2013-01-01

    We aimed to develop an alginate hydrogel (AH) modified with nano-/microfibers of titanium dioxide (nfTD) and hydroxyapatite (nfHY) and evaluated its biological and chemical properties. Nano-/microfibers of nfTD and nfHY were combined with AH, and its chemical properties were evaluated by FTIR spectroscopy, X-ray diffraction, energy dispersive X-Ray analysis, and the cytocompatibility by the WST-1 assay. The results demonstrate that the association of nfTD and nfHY nano-/microfibers to AH did not modified the chemical characteristics of the scaffold and that the association was not cytotoxic. In the first 3 h of culture with NIH/3T3 cells nfHY AH scaffolds showed a slight increase in cell viability when compared to AH alone or associated with nfTD. However, an increase in cell viability was observed in 24 h when nfTD was associated with AH scaffold. In conclusion our study demonstrates that the combination of nfHY and nfTD nano-/microfibers in AH scaffold maintains the chemical characteristics of alginate and that this association is cytocompatible. Additionally the combination of nfHY with AH favored cell viability in a short term, and the addition of nfTD increased cell viability in a long term. PMID:23862142

  17. Functionalized scaffolds to enhance tissue regeneration

    PubMed Central

    Guo, Baolin; Lei, Bo; Li, Peng; Ma, Peter X.

    2015-01-01

    Tissue engineering scaffolds play a vital role in regenerative medicine. It not only provides a temporary 3-dimensional support during tissue repair, but also regulates the cell behavior, such as cell adhesion, proliferation and differentiation. In this review, we summarize the development and trends of functional scaffolding biomaterials including electrically conducting hydrogels and nanocomposites of hydroxyapatite (HA) and bioactive glasses (BGs) with various biodegradable polymers. Furthermore, the progress on the fabrication of biomimetic nanofibrous scaffolds from conducting polymers and composites of HA and BG via electrospinning, deposition and thermally induced phase separation is discussed. Moreover, bioactive molecules and surface properties of scaffolds are very important during tissue repair. Bioactive molecule-releasing scaffolds and antimicrobial surface coatings for biomedical implants and scaffolds are also reviewed. PMID:25844177

  18. Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles.

    PubMed

    Lio, Daniel; Yeo, David; Xu, Chenjie

    2016-12-01

    Core-shell alginate-poly (lactic-co-glycolic) acid (PLGA) microparticles are potential candidates to improve hydrophilic drug loading while facilitating controlled release. This report studies the influence of the alginate core size on the drug release profile of alginate-PLGA microparticles and its size. Microparticles are synthesized through double-emulsion fabrication via a concurrent ionotropic gelation and solvent extraction. The size of alginate core ranges from approximately 10, 50, to 100 μm when the emulsification method at the first step is homogenization, vortexing, or magnetic stirring, respectively. The second step emulsification for all three conditions is performed with magnetic stirring. Interestingly, although the alginate core has different sizes, alginate-PLGA microparticle diameter does not change. However, drug release profiles are dramatically different for microparticles comprising different-sized alginate cores. Specifically, taking calcein as a model drug, microparticles containing the smallest alginate core (10 μm) show the slowest release over a period of 26 days with burst release less than 1 %. PMID:26745977

  19. Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles

    NASA Astrophysics Data System (ADS)

    Lio, Daniel; Yeo, David; Xu, Chenjie

    2016-01-01

    Core-shell alginate-poly (lactic-co-glycolic) acid (PLGA) microparticles are potential candidates to improve hydrophilic drug loading while facilitating controlled release. This report studies the influence of the alginate core size on the drug release profile of alginate-PLGA microparticles and its size. Microparticles are synthesized through double-emulsion fabrication via a concurrent ionotropic gelation and solvent extraction. The size of alginate core ranges from approximately 10, 50, to 100 μm when the emulsification method at the first step is homogenization, vortexing, or magnetic stirring, respectively. The second step emulsification for all three conditions is performed with magnetic stirring. Interestingly, although the alginate core has different sizes, alginate-PLGA microparticle diameter does not change. However, drug release profiles are dramatically different for microparticles comprising different-sized alginate cores. Specifically, taking calcein as a model drug, microparticles containing the smallest alginate core (10 μm) show the slowest release over a period of 26 days with burst release less than 1 %.

  20. Hydrogel-laden paper scaffold system for origami-based tissue engineering

    PubMed Central

    Kim, Su-Hwan; Lee, Hak Rae; Yu, Seung Jung; Han, Min-Eui; Lee, Doh Young; Kim, Soo Yeon; Ahn, Hee-Jin; Han, Mi-Jung; Lee, Tae-Ik; Kim, Taek-Soo; Kwon, Seong Keun; Im, Sung Gap; Hwang, Nathaniel S.

    2015-01-01

    In this study, we present a method for assembling biofunctionalized paper into a multiform structured scaffold system for reliable tissue regeneration using an origami-based approach. The surface of a paper was conformally modified with a poly(styrene-co-maleic anhydride) layer via initiated chemical vapor deposition followed by the immobilization of poly-l-lysine (PLL) and deposition of Ca2+. This procedure ensures the formation of alginate hydrogel on the paper due to Ca2+ diffusion. Furthermore, strong adhesion of the alginate hydrogel on the paper onto the paper substrate was achieved due to an electrostatic interaction between the alginate and PLL. The developed scaffold system was versatile and allowed area-selective cell seeding. Also, the hydrogel-laden paper could be folded freely into 3D tissue-like structures using a simple origami-based method. The cylindrically constructed paper scaffold system with chondrocytes was applied into a three-ring defect trachea in rabbits. The transplanted engineered tissues replaced the native trachea without stenosis after 4 wks. As for the custom-built scaffold system, the hydrogel-laden paper system will provide a robust and facile method for the formation of tissues mimicking native tissue constructs. PMID:26621717

  1. Hydrogel-laden paper scaffold system for origami-based tissue engineering.

    PubMed

    Kim, Su-Hwan; Lee, Hak Rae; Yu, Seung Jung; Han, Min-Eui; Lee, Doh Young; Kim, Soo Yeon; Ahn, Hee-Jin; Han, Mi-Jung; Lee, Tae-Ik; Kim, Taek-Soo; Kwon, Seong Keun; Im, Sung Gap; Hwang, Nathaniel S

    2015-12-15

    In this study, we present a method for assembling biofunctionalized paper into a multiform structured scaffold system for reliable tissue regeneration using an origami-based approach. The surface of a paper was conformally modified with a poly(styrene-co-maleic anhydride) layer via initiated chemical vapor deposition followed by the immobilization of poly-l-lysine (PLL) and deposition of Ca(2+). This procedure ensures the formation of alginate hydrogel on the paper due to Ca(2+) diffusion. Furthermore, strong adhesion of the alginate hydrogel on the paper onto the paper substrate was achieved due to an electrostatic interaction between the alginate and PLL. The developed scaffold system was versatile and allowed area-selective cell seeding. Also, the hydrogel-laden paper could be folded freely into 3D tissue-like structures using a simple origami-based method. The cylindrically constructed paper scaffold system with chondrocytes was applied into a three-ring defect trachea in rabbits. The transplanted engineered tissues replaced the native trachea without stenosis after 4 wks. As for the custom-built scaffold system, the hydrogel-laden paper system will provide a robust and facile method for the formation of tissues mimicking native tissue constructs. PMID:26621717

  2. Cardiac tissue engineering in magnetically actuated scaffolds

    NASA Astrophysics Data System (ADS)

    Sapir, Yulia; Polyak, Boris; Cohen, Smadar

    2014-01-01

    Cardiac tissue engineering offers new possibilities for the functional and structural restoration of damaged or lost heart tissue by applying cardiac patches created in vitro. Engineering such functional cardiac patches is a complex mission, involving material design on the nano- and microscale as well as the application of biological cues and stimulation patterns to promote cell survival and organization into a functional cardiac tissue. Herein, we present a novel strategy for creating a functional cardiac patch by combining the use of a macroporous alginate scaffold impregnated with magnetically responsive nanoparticles (MNPs) and the application of external magnetic stimulation. Neonatal rat cardiac cells seeded within the magnetically responsive scaffolds and stimulated by an alternating magnetic field of 5 Hz developed into matured myocardial tissue characterized by anisotropically organized striated cardiac fibers, which preserved its features for longer times than non-stimulated constructs. A greater activation of AKT phosphorylation in cardiac cell constructs after applying a short-term (20 min) external magnetic field indicated the efficacy of magnetic stimulation to actuate at a distance and provided a possible mechanism for its action. Our results point to a synergistic effect of magnetic field stimulation together with nanoparticulate features of the scaffold surface as providing the regenerating environment for cardiac cells driving their organization into functionally mature tissue.

  3. Three-dimensional electrospun alginate nanofiber mats via tailored charge repulsions.

    PubMed

    Bonino, Christopher A; Efimenko, Kirill; Jeong, Sung In; Krebs, Melissa D; Alsberg, Eben; Khan, Saad A

    2012-06-25

    The formation of 3D electrospun mat structures from alginate-polyethylene oxide (PEO) solution blends is reported. These unique architectures expand the capabilities of traditional electrospun mats for applications such as regenerative medicine, where a scaffold can help to promote tissue growth in three dimensions. The mat structures extend off the surface of the flat collector plate without the need of any modifications in the electrospinning apparatus, are self-supported when the electric field is removed, and are composed of bundles of nanofibers. A mechanism for the unique formations is proposed, based on the fiber-fiber repulsions from surface charges on the negatively charged alginate. Furthermore, the role of the electric field in the distribution of alginate within the nanofibers is discussed. X-ray photoelectron spectroscopy is used to analyze the surface composition of the electrospun nanofiber mats and the data is related to cast films made in the absence of the electric field. Further techniques to tailor the 3D architecture and nanofiber morphology by changing the surface tension and relative humidity are also discussed. PMID:22461238

  4. Alginate as a displacer for protein displacement chromatography.

    PubMed

    Chen, G; Scouten, W H

    1996-01-01

    Alginate use in displacement chromatography as a displacer has been studied. The experiments showed that untreated alginate is the basis of potential displacer for displacement chromatography, but needs to be cleaved into smaller chains. Alginate treated with ultrasound, which cleaves alginate into shorter polysaccharide chains, gave better displacement than untreated alginate, while alginate subjected to limited acid hydrolysis gave the best results in displacement chromatography. It was found that the mixture of ovalbumin and beta-lactoglobulin separated well, and several components of ovalbumin were also separated and purified when alginate hydrolysate was used as a displacer. beta-Lactoglobulins A and B, which have the same molecular weight and differ in isoelectric point by only 0.1 pH units, were displaced from Q-Sepharose by alginate hydrolysate. PMID:9174919

  5. Functionalised alginate flow seeding microparticles for use in Particle Image Velocimetry (PIV).

    PubMed

    Varela, Sylvana; Balagué, Isaac; Sancho, Irene; Ertürk, Nihal; Ferrando, Montserrat; Vernet, Anton

    2016-01-01

    Alginate microparticles as flow seeding fulfil all the requirements that are recommended for the velocity measurements in Particle Image Velocimetry (PIV). These spherical microparticles offer the advantage of being environmentally friendly, having excellent seeding properties and they can be produced via a very simple process. In the present study, the performances of alginate microparticles functionalised with a fluorescent dye, Rhodamine B (RhB), for PIV have been studied. The efficacy of fluorescence is appreciated in a number of PIV applications since it can boost the signal-to-noise ratio. Alginate microparticles functionalised with RhB have high emission efficiency, desirable match with fluid density and controlled size. The study of the particles behaviour in strong acid and basic solutions and ammonia is also included. This type of particles can be used for measurements with PIV and Planar Laser Induced Fluorescence (PLIF) simultaneously, including acid-base reactions. PMID:26878165

  6. Scaffolder - software for manual genome scaffolding

    PubMed Central

    2012-01-01

    Background The assembly of next-generation short-read sequencing data can result in a fragmented non-contiguous set of genomic sequences. Therefore a common step in a genome project is to join neighbouring sequence regions together and fill gaps. This scaffolding step is non-trivial and requires manually editing large blocks of nucleotide sequence. Joining these sequences together also hides the source of each region in the final genome sequence. Taken together these considerations may make reproducing or editing an existing genome scaffold difficult. Methods The software outlined here, “Scaffolder,” is implemented in the Ruby programming language and can be installed via the RubyGems software management system. Genome scaffolds are defined using YAML - a data format which is both human and machine-readable. Command line binaries and extensive documentation are available. Results This software allows a genome build to be defined in terms of the constituent sequences using a relatively simple syntax. This syntax further allows unknown regions to be specified and additional sequence to be used to fill known gaps in the scaffold. Defining the genome construction in a file makes the scaffolding process reproducible and easier to edit compared with large FASTA nucleotide sequences. Conclusions Scaffolder is easy-to-use genome scaffolding software which promotes reproducibility and continuous development in a genome project. Scaffolder can be found at http://next.gs. PMID:22640820

  7. An animal model study for bone repair with encapsulated differentiated osteoblasts from adipose-derived stem cells in alginate

    PubMed Central

    Hashemibeni, Batool; Esfandiari, Ebrahim; Sadeghi, Farzaneh; Heidary, Fariba; Roshankhah, Shiva; Mardani, Mohammad; Goharian, Vahid

    2014-01-01

    Objective(s): Adipose derived stem cells (ADSCs) can be engineered to express bone specific markers. The aim of this study is to evaluate repairing tibia in animal model with differentiated osteoblasts from autologous ADSCs in alginate scaffold. Materials and Methods: In this study, 6 canine's ADSCs were encapsulated in alginate and differentiated into osteoblasts. Alkaline phosphatase assay (ALP) and RT-PCR method were applied to confirm the osteogenic induction. Then, encapsulated differentiated cells (group 1) and cell-free alginate (group 2) implanted in defected part of dog's tibia for 4 and 8 weeks. Regenerated tissues and compressive strength of samples were evaluated by histological and Immunohistochemical (IHC) methods and Tensometer Universal Machine. Results: Our results showed that ADSCs were differentiated into osteoblasts in vitro, and type I collagen and osteocalcin genes expression in differentiated osteoblasts was proved by RT-PCR. In group 2, ossification and thickness of trabecula were low compared to group 1, and in both groups woven bone was observed instead of control group's compact bone. Considering time, we found bone trabeculae regression and ossification reduction after 8 weeks compared with 4 weeks in group 2, but in group 1 bone formation was increased in 8 weeks. Presence of differentiated cells caused significantly more compressive strength in comparison with group 2 (P-value ≤0.05). Conclusion: This research showed that engineering bone from differentiated adipose-derived stem cells, encapsulated in alginate can repair tibia defects. PMID:25691926

  8. Developing staining protocols for visualization of tissue-engineering scaffolds using micro computed tomography in native wet state

    PubMed Central

    Kuo, W; Nimeskern, L; Martínez, Ávila H; Hofmann, S; Freedman, J; Grinstaff, MW; Müller, R; Stok, KS

    2015-01-01

    BNC-alginate and silk fibroin tissue-engineering scaffolds were stained with X-ray contrast agents in order to visualize internal microstructure in the native wet state with microcomputed tomography. A successful protocol employing amphiphilic contrast agents (CAs) dissolved in a water-based staining solution was used. The CAs were then fixed to the scaffold by neutralizing their charged functional groups, increasing their hydrophobicity and retention on the scaffold surface in water. While some unresolved issues concerning homogeneous staining and strength of contrast remain, these first successes constitute an important milestone by identifying good contrast agent candidates and staining protocols for longitudinal monitoring of tissue-engineering studies. PMID:24042942

  9. Vanadate and triclosan synergistically induce alginate production by Pseudomonas aeruginosa strain PAO1

    PubMed Central

    Damron, F. Heath; Davis, Michael R.; Withers, T. Ryan; Ernst, Robert K.; Goldberg, Joanna B.; Yu, Guangli; Yu, Hongwei D.

    2011-01-01

    Summary Alginate overproduction by P. aeruginosa strains, also known as mucoidy, is associated with chronic lung infections in cystic fibrosis (CF). It is not clear how alginate induction occurs in the wild type (wt) mucA strains. When grown on Pseudomonas isolation agar (PIA), P. aeruginosa strains PAO1 and PA14 are nonmucoid producing minimal amounts of alginate. Here we report the addition of ammonium metavanadate (AMV), a phosphatase inhibitor, to PIA (PIA-AMV) induced mucoidy in both these laboratory strains and early lung colonizing nonmucoid isolates with a wt mucA. This phenotypic switch was reversible depending on the availability of vanadate salts and triclosan, a component of PIA. Alginate induction in PAO1 on PIA-AMV was correlated with increased proteolytic degradation of MucA, and required envelope proteases AlgW or MucP, and a two-component phosphate regulator, PhoP. Other changes included the addition of palmitate to lipid A, a phenotype also observed in chronic CF isolates. Proteomic analysis revealed the upregulation of stress chaperones, which was confirmed by increased expression of the chaperone/protease MucD. Altogether, these findings suggest a model of alginate induction and the PIA-AMV medium may be suitable for examining early lung colonization phenotypes in CF before the selection of the mucA mutants. PMID:21631603

  10. Purification and characterisation of a bifunctional alginate lyase from novel Isoptericola halotolerans CGMCC 5336.

    PubMed

    Dou, Wenfang; Wei, Dan; Li, Hui; Li, Heng; Rahman, Muhammad Masfiqur; Shi, Jinsong; Xu, Zhenghong; Ma, Yanhe

    2013-11-01

    A novel halophilic alginate-degrading microorganism was isolated from rotten seaweed and identified as Isoptericola halotolerans CGMCC5336. The lyase from the strain was purified to homogeneity by combining of ammonium sulfate fractionation and anion-exchange chromatography with a specific activity of 8409.19 U/ml and a recovery of 25.07%. This enzyme was a monomer with a molecular mass of approximately 28 kDa. The optimal temperature and pH were 50 °C and pH 7.0, respectively. The lyase maintained stability at neutral pH (7.0-8.0) and temperatures below 50 °C. Metal ions including Na(+), Mg(2+), Mn(2+), and Ca(2+) notably increased the activity of the enzyme. With sodium alginate as the substrate, the Km and Vmax were 0.26 mg/ml and 1.31 mg/ml min, respectively. The alginate lyase had substrate specificity for polyguluronate and polymannuronate units in alginate molecules, indicating its bifunctionality. These excellent characteristics demonstrated the potential applications in alginate oligosaccharides production with low polymerisation degrees. PMID:24053829

  11. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Propylene glycol alginate. 172.858 Section 172.858... Propylene glycol alginate. The food additive propylene glycol alginate (CAS Reg. No. 9005-37-2) may be used... the act: (1) The name of the additive, “propylene glycol alginate” or “propylene glycol ester...

  12. Enzymatic Hydrolysis of Alginate to Produce Oligosaccharides by a New Purified Endo-Type Alginate Lyase.

    PubMed

    Zhu, Benwei; Chen, Meijuan; Yin, Heng; Du, Yuguang; Ning, Limin

    2016-01-01

    Enzymatic hydrolysis of sodium alginate to produce alginate oligosaccharides has drawn increasing attention due to its advantages of containing a wild reaction condition, excellent gel properties and specific products easy for purification. However, the efficient commercial enzyme tools are rarely available. A new alginate lyase with high activity (24,038 U/mg) has been purified from a newly isolated marine strain, Cellulophaga sp. NJ-1. The enzyme was most active at 50 °C and pH 8.0 and maintained stability at a broad pH range (6.0-10.0) and temperature below 40 °C. It had broad substrate specificity toward sodium alginate, heteropolymeric MG blocks (polyMG), homopolymeric M blocks (polyM) and homopolymeric G blocks (polyG), and possessed higher affinity toward polyG (15.63 mM) as well as polyMG (23.90 mM) than polyM (53.61 mM) and sodium alginate (27.21 mM). The TLC and MS spectroscopy analysis of degradation products suggested that it completely hydrolyzed sodium alginate into oligosaccharides of low degrees of polymerization (DPs). The excellent properties would make it a promising tool for full use of sodium alginate to produce oligosaccharides. PMID:27275826

  13. Enzymatic Hydrolysis of Alginate to Produce Oligosaccharides by a New Purified Endo-Type Alginate Lyase

    PubMed Central

    Zhu, Benwei; Chen, Meijuan; Yin, Heng; Du, Yuguang; Ning, Limin

    2016-01-01

    Enzymatic hydrolysis of sodium alginate to produce alginate oligosaccharides has drawn increasing attention due to its advantages of containing a wild reaction condition, excellent gel properties and specific products easy for purification. However, the efficient commercial enzyme tools are rarely available. A new alginate lyase with high activity (24,038 U/mg) has been purified from a newly isolated marine strain, Cellulophaga sp. NJ-1. The enzyme was most active at 50 °C and pH 8.0 and maintained stability at a broad pH range (6.0–10.0) and temperature below 40 °C. It had broad substrate specificity toward sodium alginate, heteropolymeric MG blocks (polyMG), homopolymeric M blocks (polyM) and homopolymeric G blocks (polyG), and possessed higher affinity toward polyG (15.63 mM) as well as polyMG (23.90 mM) than polyM (53.61 mM) and sodium alginate (27.21 mM). The TLC and MS spectroscopy analysis of degradation products suggested that it completely hydrolyzed sodium alginate into oligosaccharides of low degrees of polymerization (DPs). The excellent properties would make it a promising tool for full use of sodium alginate to produce oligosaccharides. PMID:27275826

  14. Alginate Lyases from Alginate-Degrading Vibrio splendidus 12B01 Are Endolytic

    PubMed Central

    Badur, Ahmet H.; Jagtap, Sujit Sadashiv; Yalamanchili, Geethika; Lee, Jung-Kul; Zhao, Huimin

    2015-01-01

    Alginate lyases are enzymes that degrade alginate through β-elimination of the glycosidic bond into smaller oligomers. We investigated the alginate lyases from Vibrio splendidus 12B01, a marine bacterioplankton species that can grow on alginate as its sole carbon source. We identified, purified, and characterized four polysaccharide lyase family 7 alginates lyases, AlyA, AlyB, AlyD, and AlyE, from V. splendidus 12B01. The four lyases were found to have optimal activity between pH 7.5 and 8.5 and at 20 to 25°C, consistent with their use in a marine environment. AlyA, AlyB, AlyD, and AlyE were found to exhibit a turnover number (kcat) for alginate of 0.60 ± 0.02 s−1, 3.7 ± 0.3 s−1, 4.5 ± 0.5 s−1, and 7.1 ± 0.2 s−1, respectively. The Km values of AlyA, AlyB, AlyD, and AlyE toward alginate were 36 ± 7 μM, 22 ± 5 μM, 60 ± 2 μM, and 123 ± 6 μM, respectively. AlyA and AlyB were found principally to cleave the β-1,4 bonds between β-d-mannuronate and α-l-guluronate and subunits; AlyD and AlyE were found to principally cleave the α-1,4 bonds involving α-l-guluronate subunits. The four alginate lyases degrade alginate into longer chains of oligomers. PMID:25556193

  15. Microencapsulation in Alginate and Chitosan Microgels to Enhance Viability of Bifidobacterium longum for Oral Delivery

    PubMed Central

    Yeung, Timothy W.; Üçok, Elif F.; Tiani, Kendra A.; McClements, David J.; Sela, David A.

    2016-01-01

    Probiotic microorganisms are incorporated into a wide variety of foods, supplements, and pharmaceuticals to promote human health and wellness. However, maintaining bacterial cell viability during storage and gastrointestinal transit remains a challenge. Encapsulation of bifidobacteria within food-grade hydrogel particles potentially mitigates their sensitivity to environmental stresses. In this study, Bifidobacterium longum subspecies and strains were encapsulated in core-shell microgels consisting of an alginate core and a microgel shell. Encapsulated obligate anaerobes Bifidobacterium longum subsp. infantis and Bifidobacterium longum subsp. longum exhibited differences in viability in a strain-dependent manner, without a discernable relationship to subspecies lineage. This includes viability under aerobic storage conditions and modeled gastrointestinal tract conditions. Coating alginate microgels with chitosan did not improve viability compared to cells encapsulated in alginate microgels alone, suggesting that modifying the surface charge alone does not enhance delivery. Thus hydrogel beads have great potential for improving the stability and efficacy of bifidobacterial probiotics in various nutritional interventions. PMID:27148184

  16. Encapsulated dental-derived mesenchymal stem cells in an injectable and biodegradable scaffold for applications in bone tissue engineering.

    PubMed

    Moshaverinia, Alireza; Chen, Chider; Akiyama, Kentaro; Xu, Xingtian; Chee, Winston W L; Schricker, Scott R; Shi, Songtao

    2013-11-01

    Bone grafts are currently the major family of treatment options in modern reconstructive dentistry. As an alternative, stem cell-scaffold constructs seem to hold promise for bone tissue engineering. However, the feasibility of encapsulating dental-derived mesenchymal stem cells in scaffold biomaterials such as alginate hydrogel remains to be tested. The objectives of this study were, therefore, to: (1) develop an injectable scaffold based on oxidized alginate microbeads encapsulating periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs); and (2) investigate the cell viability and osteogenic differentiation of the stem cells in the microbeads both in vitro and in vivo. Microbeads with diameters of 1 ± 0.1 mm were fabricated with 2 × 10(6) stem cells/mL of alginate. Microbeads containing PDLSCs, GMSCs, and human bone marrow mesenchymal stem cells as a positive control were implanted subcutaneously and ectopic bone formation was analyzed by micro CT and histological analysis at 8-weeks postimplantation. The encapsulated stem cells remained viable after 4 weeks of culturing in osteo-differentiating induction medium. Scanning electron microscopy and X-ray diffraction results confirmed that apatitic mineral was deposited by the stem cells. In vivo, ectopic mineralization was observed inside and around the implanted microbeads containing the immobilized stem cells. These findings demonstrate for the first time that immobilization of PDLSCs and GMSCs in alginate microbeads provides a promising strategy for bone tissue engineering. PMID:23983201

  17. Composite alginate gels for tunable cellular microenvironment mechanics

    NASA Astrophysics Data System (ADS)

    Khavari, Adele; Nydén, Magnus; Weitz, David A.; Ehrlicher, Allen J.

    2016-08-01

    The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4–12 kPa) as compared to healthy tissue (E = 0.4–2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation.

  18. Composite alginate gels for tunable cellular microenvironment mechanics

    PubMed Central

    Khavari, Adele; Nydén, Magnus; Weitz, David A.; Ehrlicher, Allen J.

    2016-01-01

    The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4–12 kPa) as compared to healthy tissue (E = 0.4–2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation. PMID:27484403

  19. Composite alginate gels for tunable cellular microenvironment mechanics.

    PubMed

    Khavari, Adele; Nydén, Magnus; Weitz, David A; Ehrlicher, Allen J

    2016-01-01

    The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4-12 kPa) as compared to healthy tissue (E = 0.4-2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation. PMID:27484403

  20. In Vivo Assessment of Bone Regeneration in Alginate/Bone ECM Hydrogels with Incorporated Skeletal Stem Cells and Single Growth Factors

    PubMed Central

    Gothard, David; Smith, Emma L.; Kanczler, Janos M.; Black, Cameron R.; Wells, Julia A.; Roberts, Carol A.; White, Lisa J.; Qutachi, Omar; Peto, Heather; Rashidi, Hassan; Rojo, Luis; Stevens, Molly M.; El Haj, Alicia J.; Rose, Felicity R. A. J.; Shakesheff, Kevin M.; Oreffo, Richard O. C.

    2015-01-01

    The current study has investigated the use of decellularised, demineralised bone extracellular matrix (ECM) hydrogel constructs for in vivo tissue mineralisation and bone formation. Stro-1-enriched human bone marrow stromal cells were incorporated together with select growth factors including VEGF, TGF-β3, BMP-2, PTHrP and VitD3, to augment bone formation, and mixed with alginate for structural support. Growth factors were delivered through fast (non-osteogenic factors) and slow (osteogenic factors) release PLGA microparticles. Constructs of 5 mm length were implanted in vivo for 28 days within mice. Dense tissue assessed by micro-CT correlated with histologically assessed mineralised bone formation in all constructs. Exogenous growth factor addition did not enhance bone formation further compared to alginate/bone ECM (ALG/ECM) hydrogels alone. UV irradiation reduced bone formation through degradation of intrinsic growth factors within the bone ECM component and possibly also ECM cross-linking. BMP-2 and VitD3 rescued osteogenic induction. ALG/ECM hydrogels appeared highly osteoinductive and delivery of angiogenic or chondrogenic growth factors led to altered bone formation. All constructs demonstrated extensive host tissue invasion and vascularisation aiding integration and implant longevity. The proposed hydrogel system functioned without the need for growth factor incorporation or an exogenous inducible cell source. Optimal growth factor concentrations and spatiotemporal release profiles require further assessment, as the bone ECM component may suffer batch variability between donor materials. In summary, ALG/ECM hydrogels provide a versatile biomaterial scaffold for utilisation within regenerative medicine which may be tailored, ultimately, to form the tissue of choice through incorporation of select growth factors. PMID:26675008

  1. Review article: alginate-raft formulations in the treatment of heartburn and acid reflux.

    PubMed

    Mandel, K G; Daggy, B P; Brodie, D A; Jacoby, H I

    2000-06-01

    Alginate-based raft-forming formulations have been marketed word-wide for over 30 years under various brand names, including Gaviscon. They are used for the symptomatic treatment of heartburn and oesophagitis, and appear to act by a unique mechanism which differs from that of traditional antacids. In the presence of gastric acid, alginates precipitate, forming a gel. Alginate-based raft-forming formulations usually contain sodium or potassium bicarbonate; in the presence of gastric acid, the bicarbonate is converted to carbon dioxide which becomes entrapped within the gel precipitate, converting it into a foam which floats on the surface of the gastric contents, much like a raft on water. Both in vitro and in vivo studies have demonstrated that alginate-based rafts can entrap carbon dioxide, as well as antacid components contained in some formulations, thus providing a relatively pH-neutral barrier. Several studies have demonstrated that the alginate raft can preferentially move into the oesophagus in place, or ahead, of acidic gastric contents during episodes of gastro-oesophageal reflux; some studies further suggest that the raft can act as a physical barrier to reduce reflux episodes. Although some alginate-based formulations also contain antacid components which can provide significant acid neutralization capacity, the efficacy of these formulations to reduce heartburn symptoms does not appear to be totally dependent on the neutralization of bulk gastric contents. The strength of the alginate raft is dependant on several factors, including the amount of carbon dioxide generated and entrapped in the raft, the molecular properties of the alginate, and the presence of aluminium or calcium in the antacid components of the formulation. Raft formation occurs rapidly, often within a few seconds of dosing; hence alginate-containing antacids are comparable to traditional antacids for speed of onset of relief. Since the raft can be retained in the stomach for several

  2. Silk scaffolds for musculoskeletal tissue engineering.

    PubMed

    Yao, Danyu; Liu, Haifeng; Fan, Yubo

    2016-02-01

    The musculoskeletal system, which includes bone, cartilage, tendon/ligament, and skeletal muscle, is becoming the targets for tissue engineering because of the high need for their repair and regeneration. Numerous factors would affect the use of musculoskeletal tissue engineering for tissue regeneration ranging from cells used for scaffold seeding to the manufacture and structures of materials. The essential function of the scaffolds is to convey growth factors as well as cells to the target site to aid the regeneration of the injury. Among the variety of biomaterials used in scaffold engineering, silk fibroin is recognized as an ideal material for its impressive cytocompatibility, slow biodegradability, and excellent mechanical properties. The current review describes the advances made in the fabrication of silk fibroin scaffolds with different forms such as films, particles, electrospun fibers, hydrogels, three-dimensional porous scaffolds, and their applications in the regeneration of musculoskeletal tissues. PMID:26445979

  3. Bioactive polymeric-ceramic hybrid 3D scaffold for application in bone tissue regeneration.

    PubMed

    Torres, A L; Gaspar, V M; Serra, I R; Diogo, G S; Fradique, R; Silva, A P; Correia, I J

    2013-10-01

    The regeneration of large bone defects remains a challenging scenario from a therapeutic point of view. In fact, the currently available bone substitutes are often limited by poor tissue integration and severe host inflammatory responses, which eventually lead to surgical removal. In an attempt to address these issues, herein we evaluated the importance of alginate incorporation in the production of improved and tunable β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) three-dimensional (3D) porous scaffolds to be used as temporary templates for bone regeneration. Different bioceramic combinations were tested in order to investigate optimal scaffold architectures. Additionally, 3D β-TCP/HA vacuum-coated with alginate, presented improved compressive strength, fracture toughness and Young's modulus, to values similar to those of native bone. The hybrid 3D polymeric-bioceramic scaffolds also supported osteoblast adhesion, maturation and proliferation, as demonstrated by fluorescence microscopy. To the best of our knowledge this is the first time that a 3D scaffold produced with this combination of biomaterials is described. Altogether, our results emphasize that this hybrid scaffold presents promising characteristics for its future application in bone regeneration. PMID:23910366

  4. Recombinant protein scaffolds for tissue engineering.

    PubMed

    Werkmeister, Jerome A; Ramshaw, John A M

    2012-02-01

    New biological materials for tissue engineering are now being developed using common genetic engineering capabilities to clone and express a variety of genetic elements that allow cost-effective purification and scaffold fabrication from these recombinant proteins, peptides or from chimeric combinations of these. The field is limitless as long as the gene sequences are known. The utility is dependent on the ease, product yield and adaptability of these protein products to the biomedical field. The development of recombinant proteins as scaffolds, while still an emerging technology with respect to commercial products, is scientifically superior to current use of natural materials or synthetic polymer scaffolds, in terms of designing specific structures with desired degrees of biological complexities and motifs. In the field of tissue engineering, next generation scaffolds will be the key to directing appropriate tissue regeneration. The initial period of biodegradable synthetic scaffolds that provided shape and mechanical integrity, but no biological information, is phasing out. The era of protein scaffolds offers distinct advantages, particularly with the combination of powerful tools of molecular biology. These include, for example, the production of human proteins of uniform quality that are free of infectious agents and the ability to make suitable quantities of proteins that are found in low quantity or are hard to isolate from tissue. For the particular needs of tissue engineering scaffolds, fibrous proteins like collagens, elastin, silks and combinations of these offer further advantages of natural well-defined structural scaffolds as well as endless possibilities of controlling functionality by genetic manipulation. PMID:22262725

  5. Alginate hydrogel-mediated crystallization of calcium carbonate

    SciTech Connect

    Ma, Yufei; Feng, Qingling

    2011-05-15

    We documented a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system for the purpose of understanding the mediating function of alginate on the crystallization of calcium carbonate. The alginate was involved in the nucleation and the growth process of CaCO{sub 3}. The crystal size, morphology and roughness of crystal surface were significantly influenced by the type of the alginate, which could be accounted for by the length of the G blocks in alginate. A combination of Fourier transform infrared spectroscopy and thermogravimetric analysis showed that there were the chemical interactions between the alginate and the mineral phase. This strategic approach revealed the biologically controlled CaCO{sub 3} mineralization within calcium alginate hydrogels via the selective nucleation and the confined crystallization of CaCO{sub 3}. The results presented here could contribute to the understanding of the mineralization process in hydrogel systems. -- Graphical abstract: Schematic illustration of the growth of calcite aggregates with different morphologies obtained from (a) Low G alginate gels and (b) High G alginate gels. Display Omitted highlights: > We use a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system to understand the mediating function of alginate on the crystallization of CaCO{sub 3} crystals. > The crystal size, morphology and crystal surface roughness are influenced by the length of G blocks in alginate. There are chemical interactions between the alginate and the mineral phase. > We propose a potential mechanism of CaCO{sub 3} crystallization within High G and Low G calcium alginate hydrogel.

  6. A nano-micro alternating multilayer scaffold loading with rBMSCs and BMP-2 for bone tissue engineering.

    PubMed

    Ding, Shan; Li, Long; Liu, Xian; Yang, Guang; Zhou, Guangliang; Zhou, Shaobing

    2015-09-01

    In this study, we develop a nano-micro alternating multilayer scaffold for bone tissue engineering by incorporation of monodispersed calcium alginate microbeads into electrospun polymer nanofibers. Both rat bone marrow mesenchymal stem cells (rBMSCs) and bone morphogenetic protein-2 (BMP-2) are simultaneously loaded into the microbeads, which are generated from a microfluidic device. The layer number of the scaffold can be readily controlled by alternately repeating the electrospinning and the microfluidic processes. Alkaline phosphatase (ALP) activity and Alizarin Red S staining results demonstrate that this rBMSCs and BMP-2 loaded nano-micro alternating multilayer scaffold presents an outstanding osteogenic effect in vitro. Histological and immunohistochemical assessments further reveal that this multilayer scaffold has a significant capability of ectopic bone formation in vivo, enabling this newly developed scaffold to be suitable for wide applications in tissue engineering. PMID:26119373

  7. Characterization of the alginate biosynthetic gene cluster in Pseudomonas syringae pv. syringae.

    PubMed Central

    Peñaloza-Vázquez, A; Kidambi, S P; Chakrabarty, A M; Bender, C L

    1997-01-01

    Alginate, a copolymer of D-mannuronic acid and L-guluronic acid, is produced by a variety of pseudomonads, including Pseudomonas syringae. Alginate biosynthesis has been most extensively studied in P. aeruginosa, and a number of structural and regulatory genes from this species have been cloned and characterized. In the present study, an alginate-defective (Alg-) mutant of P. syringae pv. syringae FF5 was shown to contain a Tn5 insertion in algL, a gene encoding alginate lyase. A cosmid clone designated pSK2 restored alginate production to the algL mutant and was shown to contain homologs of algD, alg8, alg44, algG, algX (alg60), algL, algF, and algA. The order and arrangement of the structural gene cluster were virtually identical to those previously described for P. aeruginosa. Complementation analyses, however, indicated that the structural gene clusters in P. aeruginosa and P. syringae were not functionally interchangeable when expressed from their native promoters. A region upstream of the algD gene in P. syringae pv. syringae was shown to activate the transcription of a promoterless glucuronidase (uidA) gene and indicated that transcription initiated upstream of algD as described for P. aeruginosa. Transcription of the algD promoter from P. syringae FF5 was significantly higher at 32 degrees C than at 18 or 26 degrees C and was stimulated when copper sulfate or sodium chloride was added to the medium. Alginate gene expression was also stimulated by the addition of the nonionic solute sorbitol, indicating that osmolarity is a signal for algD expression in P. syringae FF5. PMID:9226254

  8. Novel bilayer bacterial nanocellulose scaffold supports neocartilage formation in vitro and in vivo.

    PubMed

    Martínez Ávila, Héctor; Feldmann, Eva-Maria; Pleumeekers, Mieke M; Nimeskern, Luc; Kuo, Willy; de Jong, Willem C; Schwarz, Silke; Müller, Ralph; Hendriks, Jeanine; Rotter, Nicole; van Osch, Gerjo J V M; Stok, Kathryn S; Gatenholm, Paul

    2015-03-01

    Tissue engineering provides a promising alternative therapy to the complex surgical reconstruction of auricular cartilage by using ear-shaped autologous costal cartilage. Bacterial nanocellulose (BNC) is proposed as a promising scaffold material for auricular cartilage reconstruction, as it exhibits excellent biocompatibility and secures tissue integration. Thus, this study evaluates a novel bilayer BNC scaffold for auricular cartilage tissue engineering. Bilayer BNC scaffolds, composed of a dense nanocellulose layer joined with a macroporous composite layer of nanocellulose and alginate, were seeded with human nasoseptal chondrocytes (NC) and cultured in vitro for up to 6 weeks. To scale up for clinical translation, bilayer BNC scaffolds were seeded with a low number of freshly isolated (uncultured) human NCs combined with freshly isolated human mononuclear cells (MNC) from bone marrow in alginate and subcutaneously implanted in nude mice for 8 weeks. 3D morphometric analysis showed that bilayer BNC scaffolds have a porosity of 75% and mean pore size of 50 ± 25 μm. Furthermore, endotoxin analysis and in vitro cytotoxicity testing revealed that the produced bilayer BNC scaffolds were non-pyrogenic (0.15 ± 0.09 EU/ml) and non-cytotoxic (cell viability: 97.8 ± 4.7%). This study demonstrates that bilayer BNC scaffolds offer a good mechanical stability and maintain a structural integrity while providing a porous architecture that supports cell ingrowth. Moreover, bilayer BNC scaffolds provide a suitable environment for culture-expanded NCs as well as a combination of freshly isolated NCs and MNCs to form cartilage in vitro and in vivo as demonstrated by immunohistochemistry, biochemical and biomechanical analyses. PMID:25617132

  9. Minimally Invasive Approach to the Repair of Injured Skeletal Muscle With a Shape-memory Scaffold

    PubMed Central

    Wang, Lin; Cao, Lan; Shansky, Janet; Wang, Zheng; Mooney, David; Vandenburgh, Herman

    2014-01-01

    Repair of injured skeletal muscle by cell therapies has been limited by poor survival of injected cells. Use of a carrier scaffold delivering cells locally, may enhance in vivo cell survival, and promote skeletal muscle regeneration. Biomaterial scaffolds are often implanted into muscle tissue through invasive surgeries, which can result in trauma that delays healing. Minimally invasive approaches to scaffold implantation are thought to minimize these adverse effects. This hypothesis was addressed in the context of a severe mouse skeletal muscle injury model. A degradable, shape-memory alginate scaffold that was highly porous and compressible was delivered by minimally invasive surgical techniques to injured tibialis anterior muscle. The scaffold controlled was quickly rehydrated in situ with autologous myoblasts and growth factors (either insulin-like growth factor-1 (IGF-1) alone or IGF-1 with vascular endothelial growth factor (VEGF)). The implanted scaffolds delivering myoblasts and IGF-1 significantly reduced scar formation, enhanced cell engraftment, and improved muscle contractile function. The addition of VEGF to the scaffold further improved functional recovery likely through increased angiogenesis. Thus, the delivery of myoblasts and dual local release of VEGF and IGF-1 from degradable scaffolds implanted through a minimally invasive procedure effectively promoted the functional regeneration of injured skeletal muscle. PMID:24769909

  10. Stereolithographic Bone Scaffold Design Parameters: Osteogenic Differentiation and Signal Expression

    PubMed Central

    Kim, Kyobum; Yeatts, Andrew; Dean, David

    2010-01-01

    Scaffold design parameters including porosity, pore size, interconnectivity, and mechanical properties have a significant influence on osteogenic signal expression and differentiation. This review evaluates the influence of each of these parameters and then discusses the ability of stereolithography (SLA) to be used to tailor scaffold design to optimize these parameters. Scaffold porosity and pore size affect osteogenic cell signaling and ultimately in vivo bone tissue growth. Alternatively, scaffold interconnectivity has a great influence on in vivo bone growth but little work has been done to determine if interconnectivity causes changes in signaling levels. Osteogenic cell signaling could be also influenced by scaffold mechanical properties such as scaffold rigidity and dynamic relationships between the cells and their extracellular matrix. With knowledge of the effects of these parameters on cellular functions, an optimal tissue engineering scaffold can be designed, but a proper technology must exist to produce this design to specification in a repeatable manner. SLA has been shown to be capable of fabricating scaffolds with controlled architecture and micrometer-level resolution. Surgical implantation of these scaffolds is a promising clinical treatment for successful bone regeneration. By applying knowledge of how scaffold parameters influence osteogenic cell signaling to scaffold manufacturing using SLA, tissue engineers may move closer to creating the optimal tissue engineering scaffold. PMID:20504065

  11. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS...

  12. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS...

  13. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS...

  14. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...: Category of food Maximum level of use in food (as served) (percent) Functional use Confections, frostings... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ammonium alginate. 184.1133 Section 184.1133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  15. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ammonium alginate. 184.1133 Section 184.1133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS...

  16. Scaffold Translation: Barriers Between Concept and Clinic

    PubMed Central

    Murphy, William L.

    2011-01-01

    Translation of scaffold-based bone tissue engineering (BTE) therapies to clinical use remains, bluntly, a failure. This dearth of translated tissue engineering therapies (including scaffolds) remains despite 25 years of research, research funding totaling hundreds of millions of dollars, over 12,000 papers on BTE and over 2000 papers on BTE scaffolds alone in the past 10 years (PubMed search). Enabling scaffold translation requires first an understanding of the challenges, and second, addressing the complete range of these challenges. There are the obvious technical challenges of designing, manufacturing, and functionalizing scaffolds to fill the Form, Fixation, Function, and Formation needs of bone defect repair. However, these technical solutions should be targeted to specific clinical indications (e.g., mandibular defects, spine fusion, long bone defects, etc.). Further, technical solutions should also address business challenges, including the need to obtain regulatory approval, meet specific market needs, and obtain private investment to develop products, again for specific clinical indications. Finally, these business and technical challenges present a much different model than the typical research paradigm, presenting the field with philosophical challenges in terms of publishing and funding priorities that should be addressed as well. In this article, we review in detail the technical, business, and philosophical barriers of translating scaffolds from Concept to Clinic. We argue that envisioning and engineering scaffolds as modular systems with a sliding scale of complexity offers the best path to addressing these translational challenges. PMID:21902613

  17. Falsirhodobacter sp. alg1 Harbors Single Homologs of Endo and Exo-Type Alginate Lyases Efficient for Alginate Depolymerization

    PubMed Central

    Takahashi, Mami; Tanaka, Reiji; Miyake, Hideo; Shibata, Toshiyuki; Chow, Seinen; Kuroda, Kouichi; Ueda, Mitsuyoshi; Takeyama, Haruko

    2016-01-01

    Alginate-degrading bacteria play an important role in alginate degradation by harboring highly efficient and unique alginolytic genes. Although the general mechanism for alginate degradation by these bacteria is fairly understood, much is still required to fully exploit them. Here, we report the isolation of a novel strain, Falsirhodobacter sp. alg1, the first report for an alginate-degrading bacterium from the family Rhodobacteraceae. Genome sequencing reveals that strain alg1 harbors a primary alginate degradation pathway with only single homologs of an endo- and exo-type alginate lyase, AlyFRA and AlyFRB, which is uncommon among such bacteria. Subsequent functional analysis showed that both enzymes were extremely efficient to depolymerize alginate suggesting evolutionary interests in the acquirement of these enzymes. The exo-type alginate lyase, AlyFRB in particular could depolymerize alginate without producing intermediate products making it a highly efficient enzyme for the production of 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEH). Based on our findings, we believe that the discovery of Falsirhodobacter sp. alg1 and its alginolytic genes hints at the potentiality of a more diverse and unique population of alginate-degrading bacteria. PMID:27176711

  18. [Bone tissue engineering scaffolds].

    PubMed

    Fang, Liru; Weng, Wenjian; Shen, Ge; Han, Gaorong; Santos, J D; Du, Peiyi

    2003-03-01

    Bone tissue engineering may provide an alternative to the repairs to skeletal defects resulting from disease, trauma or surgery. Scaffold has played an important role in bone tissue engineering, which functions as the architecture for bone in growth. In this paper, the authors gave a brief introduction about the requirement of bone tissue engineering scaffold, the key of the design of scaffolds and the current research on this subject. PMID:12744187

  19. Sustained Release of BMP-2 in Bioprinted Alginate for Osteogenicity in Mice and Rats

    PubMed Central

    Poldervaart, Michelle T.; Wang, Huanan; van der Stok, Johan; Weinans, Harrie; Leeuwenburgh, Sander C. G.; Öner, F. Cumhur; Dhert, Wouter J. A.; Alblas, Jacqueline

    2013-01-01

    The design of bioactive three-dimensional (3D) scaffolds is a major focus in bone tissue engineering. Incorporation of growth factors into bioprinted scaffolds offers many new possibilities regarding both biological and architectural properties of the scaffolds. This study investigates whether the sustained release of bone morphogenetic protein 2 (BMP-2) influences osteogenicity of tissue engineered bioprinted constructs. BMP-2 loaded on gelatin microparticles (GMPs) was used as a sustained release system, which was dispersed in hydrogel-based constructs and compared to direct inclusion of BMP-2 in alginate or control GMPs. The constructs were supplemented with goat multipotent stromal cells (gMSCs) and biphasic calcium phosphate to study osteogenic differentiation and bone formation respectively. BMP-2 release kinetics and bioactivity showed continuous release for three weeks coinciding with osteogenicity. Osteogenic differentiation and bone formation of bioprinted GMP containing constructs were investigated after subcutaneous implantation in mice or rats. BMP-2 significantly increased bone formation, which was not influenced by the release timing. We showed that 3D printing of controlled release particles is feasible and that the released BMP-2 directs osteogenic differentiation in vitro and in vivo. PMID:23977328

  20. Structural properties of scaffolds: Crucial parameters towards stem cells differentiation

    PubMed Central

    Ghasemi-Mobarakeh, Laleh; Prabhakaran, Molamma P; Tian, Lingling; Shamirzaei-Jeshvaghani, Elham; Dehghani, Leila; Ramakrishna, Seeram

    2015-01-01

    Tissue engineering is a multidisciplinary field that applies the principles of engineering and life-sciences for regeneration of damaged tissues. Stem cells have attracted much interest in tissue engineering as a cell source due to their ability to proliferate in an undifferentiated state for prolonged time and capability of differentiating to different cell types after induction. Scaffolds play an important role in tissue engineering as a substrate that can mimic the native extracellular matrix and the properties of scaffolds have been shown to affect the cell behavior such as the cell attachment, proliferation and differentiation. Here, we focus on the recent reports that investigated the various aspects of scaffolds including the materials used for scaffold fabrication, surface modification of scaffolds, topography and mechanical properties of scaffolds towards stem cells differentiation effect. We will present a more detailed overview on the effect of mechanical properties of scaffolds on stem cells fate. PMID:26029344

  1. The host response to allogeneic and xenogeneic biological scaffold materials.

    PubMed

    Keane, Timothy J; Badylak, Stephen F

    2015-05-01

    The clinical use of biological scaffold materials has become commonplace. Such scaffolds are composed of extracellular matrix (ECM), or components of ECM, derived from allogeneic or xenogeneic tissues. Such scaffold materials vary widely in their source tissue, processing methods and sterilization methods. The success or failure of an ECM scaffold for a given application is dependent on the host response following implantation; a response that is largely mediated by the innate immune system and which is influenced by a numerous factors, including the processing methods used in the preparation of biological scaffolds. The present paper reviews various aspects of the host response to biological scaffolds and factors that affect this response. In addition, some of the logistical, regulatory and reconstructive implications associated with the use of biological scaffolds are discussed. PMID:24668694

  2. Antibacterial Performance of Alginic Acid Coating on Polyethylene Film

    PubMed Central

    Karbassi, Elika; Asadinezhad, Ahmad; Lehocký, Marian; Humpolíček, Petr; Vesel, Alenka; Novák, Igor; Sáha, Petr

    2014-01-01

    Alginic acid coated polyethylene films were examined in terms of surface properties and bacteriostatic performance against two most representative bacterial strains, that is, Escherichia coli and Staphylococcus aureus. Microwave plasma treatment followed by brush formation in vapor state from three distinguished precursors (allylalcohol, allylamine, hydroxyethyl methacrylate) was carried out to deposit alginic acid on the substrate. Surface analyses via various techniques established that alginic acid was immobilized onto the surface where grafting (brush) chemistry influenced the amount of alginic acid coated. Moreover, alginic acid was found to be capable of bacterial growth inhibition which itself was significantly affected by the brush type. The polyanionic character of alginic acid as a carbohydrate polymer was assumed to play the pivotal role in antibacterial activity. The cell wall composition of two bacterial strains along with the substrates physicochemical properties accounted for different levels of bacteriostatic performance. PMID:25196604

  3. Galactosylated alginate-curcumin micelles for enhanced delivery of curcumin to hepatocytes.

    PubMed

    P R, Sarika; James, Nirmala Rachel; Kumar P R, Anil; K Raj, Deepa

    2016-05-01

    Galactosylated alginate-curcumin conjugate (LANH2-Alg Ald-Cur) is synthesized for targeted delivery of curcumin to hepatocytes exploiting asialoglycoprotein receptor (ASGPR) on hepatocytes. The synthetic procedure includes oxidation of alginate (Alg), modification of lactobionic acid (LA), grafting of targeting group (modified lactobinic acid, LANH2) and conjugation of curcumin to alginate. Alginate-curcumin conjugate (Alg-Cur) without targeting group is also prepared for the comparison of properties. LANH2-Alg Ald-Cur self assembles to micelle with diameter of 235±5nm and zeta potential of -29mV in water. Cytotoxicity analysis demonstrates enhanced toxicity of LANH2-Alg Ald-Cur over Alg-Cur on HepG2 cells. Cellular uptake studies confirm that LANH2-Alg Ald-Cur can selectively recognize HepG2 cells and shows higher internalization than Alg-Cur conjugate. Results indicate that LANH2-Alg Ald-Cur conjugate micelles are suitable candidates for targeted delivery of curcumin to HepG2 cells. PMID:26774374

  4. Comparative characterization of three bacterial exo-type alginate lyases.

    PubMed

    Hirayama, Makoto; Hashimoto, Wataru; Murata, Kousaku; Kawai, Shigeyuki

    2016-05-01

    Alginate, a major acidic polysaccharide in brown macroalgae, has attracted attention as a carbon source for production of ethanol and other chemical compounds. Alginate is monomerized by exo-type alginate lyase into an unsaturated uronate; thus, this enzyme is critical for the saccharification and utilization of alginate. Although several exo-type alginate lyases have been characterized independently, their activities were not assayed under the same conditions or using the same unit definition, making it difficult to compare enzymatic properties or to select the most suitable enzyme for saccharification of alginate. In this study, we characterized the three bacterial exo-type alginate lyases under the same conditions: A1-IV of Sphingomonas sp. strain A1, Atu3025 of Agrobacterium tumefaciens, and Alg17c of Saccharophagus degradans. A1-IV had the highest specific activity as well as the highest productivity of uronate, whereas Alg17c had the lowest activity and productivity. Only dialyzed Atu3025 and Alg17c were tolerant to freezing. Alg17c exhibited a remarkable halotolerance, which may be advantageous for monomerization of alginate from marine brown algae. Thus, each enzyme exhibited particular desirable and undesirable properties. Our results should facilitate further utilization of the promising polysaccharide alginate. PMID:26827758

  5. PLGA/alginate composite microspheres for hydrophilic protein delivery.

    PubMed

    Zhai, Peng; Chen, X B; Schreyer, David J

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate. PMID:26249587

  6. The comparative bioavailability of cimetidine-alginate treatments.

    PubMed

    Britton, A M; Nichols, J D; Draper, P R

    1991-02-01

    The comparative bioavailability of cimetidine in cimetidine-alginate combinations has been investigated in twelve healthy volunteers in an open crossover study. Each volunteer received a single oral dose of a commercially available alginate-cimetidine combination tablet (Algitec) or cimetidine tablets (Tagamet), co-administered with a commercially available alginate reflux suppressant liquid or tablet (Gaviscon). No significant differences were observed between treatments for Cmax, tmax, AUC0-12 or AUC0- infinity. The study demonstrated equivalent bioavailability of cimetidine when administered separately with alginate products and as a fixed dose combination product. PMID:1672897

  7. Sterilization techniques for biodegradable scaffolds in tissue engineering applications

    PubMed Central

    Dai, Zheng; Ronholm, Jennifer; Tian, Yiping; Sethi, Benu; Cao, Xudong

    2016-01-01

    Biodegradable scaffolds have been extensively studied due to their wide applications in biomaterials and tissue engineering. However, infections associated with in vivo use of these scaffolds by different microbiological contaminants remain to be a significant challenge. This review focuses on different sterilization techniques including heat, chemical, irradiation, and other novel sterilization techniques for various biodegradable scaffolds. Comparisons of these techniques, including their sterilization mechanisms, post-sterilization effects, and sterilization efficiencies, are discussed. PMID:27247758

  8. Chitin Scaffolds in Tissue Engineering

    PubMed Central

    Jayakumar, Rangasamy; Chennazhi, Krishna Prasad; Srinivasan, Sowmya; Nair, Shantikumar V.; Furuike, Tetsuya; Tamura, Hiroshi

    2011-01-01

    Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine. PMID:21673928

  9. Redox-responsive alginate microsphere containing cystamine.

    PubMed

    Kwon, Kyeongnan; Kim, Jin-Chul

    2016-10-01

    Redox-responsive microspheres were prepared by solidifying the alginate- and cystamine-containing water droplets of O/W emulsion using calcium ion. Emulsions were prepared using alginate/cystamine mixture solution whose the carboxylic group/the amino group molar ratio was 1:1, 1:2, and 1:3, and whose the total concentration was kept to 2% (w/v). The microspheres on Scanning electron microscopy photographs were almost spherical and they were less than 1 μm in diameter. According to the energy-dispersive X-ray spectroscopy, the sulfur content of the microspheres was found to be 6.1, 11.4, and 14.8% (w/w), respectively, not markedly different from the calculated content. The release degree of blue dextran loaded in the microspheres was higher as the cystamine content was higher. Microspheres released almost the same amount of dye regardless of dithiothreitol (DTT, a reducing agent) concentration when the cystamine content was relatively low (e.g. 14.5% (w/w)), whereas they released dye in DTT concentration-dependent manner when the cystamine content was relatively high (e.g. 27.0 and 35.1% (w/w)). The light scattering intensity of alginate/cystamine mixture solution was stronger at a larger amount of cystamine, indicating that cystamine could cross-link alginate chains. The light scattering intensity decreased with increasing DTT concentration, possibly because of the breakdown of the disulfide bond of cystamine. The breakdown of the disulfide bond could account for why the DTT concentration-dependent release of dye loaded in the microspheres was observed. PMID:27484719

  10. An Alginate-based Hybrid System for Growth Factor Delivery in the Functional Repair of Large Bone Defects

    PubMed Central

    Kolambkar, Yash M.; Dupont, Kenneth M.; Boerckel, Joel D.; Huebsch, Nathaniel; Mooney, David J.; Hutmacher, Dietmar W.

    2010-01-01

    The treatment of challenging fractures and large osseous defects presents a formidable problem for orthopaedic surgeons. Tissue engineering/regenerative medicine approaches seek to solve this problem by delivering osteogenic signals within scaffolding biomaterials. In this study, we introduce a hybrid growth factor delivery system that consists of an electrospun nanofiber mesh tube for guiding bone regeneration combined with peptide-modified alginate hydrogel injected inside the tube for sustained growth factor release. We tested the ability of this system to deliver recombinant bone morphogenetic protein-2 (rhBMP-2) for the repair of critically-sized segmental bone defects in a rat model. Longitudinal μ-CT analysis and torsional testing provided quantitative assessment of bone regeneration. Our results indicate that the hybrid delivery system resulted in consistent bony bridging of the challenging bone defects. However, in the absence of rhBMP-2, the use of nanofiber mesh tube and alginate did not result in substantial bone formation. Perforations in the nanofiber mesh accelerated the rhBMP-2 mediated bone repair, and resulted in functional restoration of the regenerated bone. μ-CT based angiography indicated that perforations did not significantly affect the revascularization of defects, suggesting that some other interaction with the tissue surrounding the defect such as improved infiltration of osteoprogenitor cells contributed to the observed differences in repair. Overall, our results indicate that the hybrid alginate/nanofiber mesh system is a promising growth factor delivery strategy for the repair of challenging bone injuries. PMID:20864165