Surface topography of hairy cell leukemia cells compared to other leukemias as seen by scanning electron microscopy.

PubMed

Polliack, Aaron; Tadmor, Tamar

2011-06-01

This short review deals with the ultrastructural surface architecture of hairy cell leukemia (HCL) compared to other leukemic cells, as seen by scanning electron microscopy (SEM). The development of improved techniques for preparing blood cells for SEM in the 1970s readily enabled these features to be visualized more accurately. This review returns us to the earlier history of SEM, when the surface topography of normal and neoplastic cells was visualized and reported for the first time, in an era before the emergence and use of monoclonal antibodies and flow cytometry, now used routinely to define cells by their immunophenotype. Surface microvilli are characteristic for normal and leukemic lymphoid cells, myelo-monocytic cells lack microvilli and show surface ruffles, while leukemic plasma and myeloma cells and megakaryocytes display large surface blebs. HCL cell surfaces are complex and typically 'hybrid' in nature, displaying both lymphoid and monocytic features with florid ruffles of varying sizes interspersed with clumps of short microvilli cytoplasm. The surface features of other leukemic cells and photomicrographs of immuno-SEM labeling of cells employing antibodies and colloidal gold, reported more than 20 years ago, are shown.

Redesigning of Microbial Cell Surface and Its Application to Whole-Cell Biocatalysis and Biosensors.

PubMed

Han, Lei; Zhao, Yukun; Cui, Shan; Liang, Bo

2018-06-01

Microbial cell surface display technology can redesign cell surfaces with functional proteins and peptides to endow cells some unique features. Foreign peptides or proteins are transported out of cells and immobilized on cell surface by fusing with anchoring proteins, which is an effective solution to avoid substance transfer limitation, enzyme purification, and enzyme instability. As the most frequently used prokaryotic and eukaryotic protein surface display system, bacterial and yeast surface display systems have been widely applied in vaccine, biocatalysis, biosensor, bioadsorption, and polypeptide library screening. In this review of bacterial and yeast surface display systems, different cell surface display mechanisms and their applications in biocatalysis as well as biosensors are described with their strengths and shortcomings. In addition to single enzyme display systems, multi-enzyme co-display systems are presented here. Finally, future developments based on our and other previous reports are discussed.

Antibacterial and anticancer PDMS surface for mammalian cell growth using the Chinese herb extract paeonol(4-methoxy-2-hydroxyacetophenone)

NASA Astrophysics Data System (ADS)

Jiao, Jiajia; Sun, Lili; Guo, Zaiyu; Hou, Sen; Holyst, Robert; Lu, Yun; Feng, Xizeng

2016-12-01

Polydimethylsiloxane (PDMS) is widely used as a cell culture platform to produce micro- and nano-technology based microdevices. However, the native PDMS surface is not suitable for cell adhesion and is always subject to bacterial pollution and cancer cell invasion. Coating the PDMS surface with antibacterial or anticancer materials often causes considerable harm to the non-cancer mammalian cells on it. We have developed a method to fabricate a biocompatible PDMS surface which not only promotes non-cancer mammalian cell growth but also has antibacterial and anticancer activities, by coating the PDMS surface with a Chinese herb extract, paeonol. Coating changes the wettability and the elemental composition of the PDMS surface. Molecular dynamic simulation indicates that the absorption of paeonol onto the PDMS surface is an energy favourable process. The paeonol-coated PDMS surface exhibits good antibacterial activity against both Gram-positive and Gram-negative bacteria. Moreover considerable antibacterial activity is maintained after the coated surface is rinsed or incubated in water. The coated PDMS surface inhibits bacterial growth on the contact surface and promotes non-cancer mammalian cell growth with low cell toxicity; meanwhile the growth of cancer cells is significantly inhibited. Our study will potentially guide PDMS surface modification approaches to produce biomedical devices.

Simian virus 40 T-antigen-related cell surface antigen: serological demonstration on simian virus 40-transformed monolayer cells in situ.

PubMed Central

Deppert, W; Hanke, K; Henning, R

1980-01-01

Simian virus 40 (SV40)-transformed monolayer cells were analyzed in situ by indirect immunofluorescence microscopy for the postulated cell surface location of SV40 T-antigen-related molecules. With antisera prepared against purified, sodium dodecyl sulfate-denatured SV40 T-antigen, positive surface staining was obtained when the cells had been treated with formaldehyde before immunofluorescence analysis. In contrast, living SV40-transformed cells analyzed in monolayer were surface fluorescence negative. The fixation procedure developed in this study combined with a double staining immunofluorescence technique allowed the simultaneous analysis of the same cells for the expression of both SV40 T-antigen-related surface antigen and nuclear T-antigen. The localization of SV40 T-antigen-related surface antigen on the outer surface of the plasma membrane of formaldehyde-fixed SV40-transformed cells was demonstrated directly by the protein A-mediated binding of Staphylococcus aureus bacteria on formaldehyde-fixed SV40-transformed cells precoated with antiserum against sodium dodecyl sulfate-denatured T-antigen. Both cell surface staining and S. aureus binding were found to be highly specific for SV40 T-antigen-related binding sites. These results indicate that T-antigen-related molecules in a cryptic form are located on the surface of SV40-transformed monolayer cells and can be detected in situ after modification of the cell surface architecture. Images PMID:6255189

Multigenerational memory and adaptive adhesion in early bacterial biofilm communities.

PubMed

Lee, Calvin K; de Anda, Jaime; Baker, Amy E; Bennett, Rachel R; Luo, Yun; Lee, Ernest Y; Keefe, Joshua A; Helali, Joshua S; Ma, Jie; Zhao, Kun; Golestanian, Ramin; O'Toole, George A; Wong, Gerard C L

2018-04-24

Using multigenerational, single-cell tracking we explore the earliest events of biofilm formation by Pseudomonas aeruginosa During initial stages of surface engagement (≤20 h), the surface cell population of this microbe comprises overwhelmingly cells that attach poorly (∼95% stay <30 s, well below the ∼1-h division time) with little increase in surface population. If we harvest cells previously exposed to a surface and direct them to a virgin surface, we find that these surface-exposed cells and their descendants attach strongly and then rapidly increase the surface cell population. This "adaptive," time-delayed adhesion requires determinants we showed previously are critical for surface sensing: type IV pili (TFP) and cAMP signaling via the Pil-Chp-TFP system. We show that these surface-adapted cells exhibit damped, coupled out-of-phase oscillations of intracellular cAMP levels and associated TFP activity that persist for multiple generations, whereas surface-naïve cells show uncorrelated cAMP and TFP activity. These correlated cAMP-TFP oscillations, which effectively impart intergenerational memory to cells in a lineage, can be understood in terms of a Turing stochastic model based on the Pil-Chp-TFP framework. Importantly, these cAMP-TFP oscillations create a state characterized by a suppression of TFP motility coordinated across entire lineages and lead to a drastic increase in the number of surface-associated cells with near-zero translational motion. The appearance of this surface-adapted state, which can serve to define the historical classification of "irreversibly attached" cells, correlates with family tree architectures that facilitate exponential increases in surface cell populations necessary for biofilm formation.

Microarray of neuroblastoma cells on the selectively functionalized nanocrystalline diamond thin film surface

NASA Astrophysics Data System (ADS)

Park, Young-Sang; Son, Hyeong-Guk; Kim, Dae-Hoon; Oh, Hong-Gi; Lee, Da-Som; Kim, Min-Hye; Lim, Ki-Moo; Song, Kwang-Soup

2016-01-01

Nanocrystalline diamond (NCD) film surfaces were modified with fluorine or oxygen by plasma treatment in an O2 or C3F8 gas environment in order to induce wettability. The oxygenated-NCD (O-NCD) film surface was hydrophilic and the fluorinated-NCD (F-NCD) surface was hydrophobic. The efficiency of early cell adhesion, which is dependent on the wettability of the cell culture plate and necessary for the growth and proliferation of cells, was 89.62 ± 3.92% on the O-NCD film and 7.78 ± 0.77% on the F-NCD film surface after 3 h of cell culture. The wettability of the NCD film surface was artificially modified using a metal mask and plasma treatment to fabricate a micro-pattern. Four types of micro-patterns were fabricated (line, circle, mesh, and word) on the NCD film surface. We precisely arrayed the neuroblastoma cells on the micro-patterned NCD film surfaces by controlling the surface wettability and cell seeding density. The neuroblastoma cells adhered and proliferated along the O-NCD film surface.

A monoclonal antibody recognizes undifferentiation-specific carbohydrate moieties expressed on cell surface of the human dental pulp cells.

PubMed

Kang, Kyung-Jung; Ko, Seon-Yle; Ryu, Chun-Jeih; Jang, Young-Joo

2017-05-01

Human dental pulp cells are obtained from dental pulp tissue, and have the ability to form dentin and a pulp-like complex. Although adult stem cells have been identified from the primary culture by using specific cell surface markers, the identity of surface markers for the purification of stem cells within the dental pulp population are still unclear. Previously, we had constructed monoclonal antibodies against the undifferentiated cell-specific surface markers of human dental pulp cells (hDPCs) by performing decoy immunization. Among them, a monoclonal antibody against the cell surface antigen of the undifferentiated hDPCs (named UPSA-1) was purified and its heavy and light chain consensus regions were analyzed. The cell surface binding affinity of UPSA-1 mAb on the undifferentiated hDPCs was stronger than that on the differentiated cells. When tunicamycin was applied to hDPSCs during culture, the cell surface binding affinity of the antibody was dramatically decreased, and dentinogenic differentiation was reduced. The purified UPSA-1 antigen band resulting from immunoprecipitation disappeared or shifted down on the SDS-PAGE by deglycosylation. These data suggested that glycosylation on the cell surface might be a marker of an undifferentiated state, and that UPSA-1 mAb might be useful for identifying the carbohydrate moiety on the cell surface of undifferentiated pulp cells. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Label-free detection of surface markers on stem cells by oblique-incidence reflectivity difference microscopy

PubMed Central

Lo, Kai-Yin; Sun, Yung-Shin; Landry, James P.; Zhu, Xiangdong; Deng, Wenbin

2012-01-01

Conventional fluorescent microscopy is routinely used to detect cell surface markers through fluorophore-conjugated antibodies. However, fluorophore-conjugation of antibodies alters binding properties such as strength and specificity of the antibody in ways often uncharacterized. The binding between antibody and antigen might not be in the native situation after such conjugation. Here, we present an oblique-incidence reflectivity difference (OI-RD) microscope as an effective method for label-free, real-time detection of cell surface markers and apply such a technique to analysis of Stage-Specific Embryonic Antigen 1 (SSEA1) on stem cells. Mouse stem cells express SSEA1 on their surfaces and the level of SSEA1 decreases when the cells start to differentiate. In this study, we immobilized mouse stem cells and non-stem cells (control) on a glass surface as a microarray and reacted the cell microarray with unlabeled SSEA1 antibodies. By monitoring the reaction with an OI-RD microscope in real time, we confirmed that the SSEA1 antibodies only bind to the surface of the stem cells while not to the surface of non-stem cells. From the binding curves, we determined the equilibrium dissociation constant (Kd) of the antibody with the SSEA1 markers on the stem cell surface. The results concluded that OI-RD microscope can be used to detect binding affinities between cell surface markers and unlabeled antibodies bound to the cells. The information could be another indicator to determine the cell stages. PMID:21781038

Clustering of adhesion receptors following exposure of insect blood cells to foreign surfaces.

PubMed

Nardi, James B; Zhuang, Shufei; Pilas, Barbara; Bee, Charles Mark; Kanost, Michael R

2005-05-01

Cell-mediated immune responses of insects involve interactions of two main classes of blood cells (hemocytes) known as granular cells and plasmatocytes. In response to a foreign surface, these hemocytes suddenly transform from circulating, non-adherent cells to cells that interact and adhere to each other and the foreign surface. This report presents evidence that during this adhesive transformation the extracellular matrix (ECM) proteins lacunin and a ligand for peanut agglutinin (PNA) lectin are released by granular cells and bind to surfaces of both granular cells and plasmatocytes. ECM protein co-localizes on cell surfaces with the adhesive receptors integrin and neuroglian, a member of the immunoglobulin superfamily. The ECM protein(s) secreted by granular cells are hypothesized to interact with adhesion receptors such as neuroglian and integrin by cross linking and clustering them on hemocyte surfaces. This clustering of receptors is known to enhance the adhesiveness (avidity) of interacting mammalian immune cells. The formation of ring-shaped clusters of these adhesion receptors on surfaces of insect immune cells represents an evolutionary antecedent of the mammalian immunological synapse.

Cell morphology, viability, osteocalcin activity, and alkaline phosphatase activity in milled versus unmilled surface of the femoral head.

PubMed

Rhyu, Kee Hyung; Cho, Chang Hoon; Yoon, Kyung Sik; Chun, Young Soo

2016-12-01

To evaluate cellular activity in milled versus unmilled surface of the femoral head in 21 patients who underwent robot-assisted total hip arthroplasty(THA). The femoral head of 21 consecutive patients who underwent robot-assisted THA for osteonecrosis was used. 10 cc of trabecular bone from the entire milled surface was obtained using a curette. The same amount of trabecular bone was obtained at least 1 cm away from the milled surface and served as a matched control. Cell morphology, viability, osteocalcin activity, and alkaline phosphatase activity in milled versus unmilled surface were assessed. Cell morphology of the milled or unmilled surface was comparable; cells were smaller in the milled surface. Cell viability was a mean of 40% higher in the milled surface (107.4% vs. 67.2%, p<0.001); cell viability at 5 time points was comparable in each group. Osteocalcin activity of cells was slightly higher in the milled surface (1.43 vs. 1.24 ng/ml, p=0.69). Alkaline phosphatase activity of cells was slightly higher in the unmilled surface (150 105 vs. 141 789 U/L, p=0.078). The milled and unmilled surfaces of the femoral head were comparable in terms of cell morphology, viability, osteocalcin activity, and alkaline phosphatase activity.

Physical labeling of papillomavirus-infected, immortal, and cancerous cervical epithelial cells reveal surface changes at immortal stage.

PubMed

Swaminathan Iyer, K; Gaikwad, R M; Woodworth, C D; Volkov, D O; Sokolov, Igor

2012-06-01

A significant change of surface features of malignant cervical epithelial cells compared to normal cells has been previously reported. Here, we are studying the question at which progressive stage leading to cervical cancer the surface alteration happens. A non-traditional method to identify malignant cervical epithelial cells in vitro, which is based on physical (in contrast to specific biochemical) labelling of cells with fluorescent silica micron-size beads, is used here to examine cells at progressive stages leading to cervical cancer which include normal epithelial cells, cells infected with human papillomavirus type-16 (HPV-16), cells immortalized by HPV-16, and carcinoma cells. The study shows a statistically significant (at p < 0.01) difference between both immortal and cancer cells and a group consisting of normal and infected. There is no significant difference between normal and infected cells. Immortal cells demonstrate the signal which is closer to cancer cells than to either normal or infected cells. This implies that the cell surface, surface cellular brush changes substantially when cells become immortal. Physical labeling of the cell surface represents a substantial departure from the traditional biochemical labeling methods. The results presented show the potential significance of physical properties of the cell surface for development of clinical methods for early detection of cervical cancer, even at the stage of immortalized, premalignant cells.

Physical Labeling of Papillomavirus-Infected, Immortal, and Cancerous Cervical Epithelial Cells Reveal Surface Changes at Immortal Stage

PubMed Central

Iyer, K. Swaminathan; Gaikwad, R. M.; Woodworth, C. D.; Volkov, D. O.

2013-01-01

A significant change of surface features of malignant cervical epithelial cells compared to normal cells has been previously reported. Here, we are studying the question at which progressive stage leading to cervical cancer the surface alteration happens. A non-traditional method to identify malignant cervical epithelial cells in vitro, which is based on physical (in contrast to specific biochemical) labelling of cells with fluorescent silica micron-size beads, is used here to examine cells at progressive stages leading to cervical cancer which include normal epithelial cells, cells infected with human papillomavirus type-16 (HPV-16), cells immortalized by HPV-16, and carcinoma cells. The study shows a statistically significant (at p <0.01) difference between both immortal and cancer cells and a group consisting of normal and infected. There is no significant difference between normal and infected cells. Immortal cells demonstrate the signal which is closer to cancer cells than to either normal or infected cells. This implies that the cell surface, surface cellular brush changes substantially when cells become immortal. Physical labeling of the cell surface represents a substantial departure from the traditional biochemical labeling methods. The results presented show the potential significance of physical properties of the cell surface for development of clinical methods for early detection of cervical cancer, even at the stage of immortalized, pre-malignant cells. PMID:22351422

Prolymphocytic leukaemia: surface morphology in 21 cases as seen by scanning electron microscopy and comparison with B-type CLL and CLL in 'prolymphocytoid' transformation.

PubMed

Polliack, A; Leizerowitz, R; Berrebi, A; Gamliel, H; Galili, N; Gurfel, D; Catovsky, D

1984-08-01

The surface architecture of leukaemic cells obtained from 21 cases of proven prolymphocytic leukaemia (PLL) and eight cases of chronic lymphocytic leukaemia (CLL) with 'prolymphocytoid' transformation (PL-CLL) was compared with the cell surface morphology of leukaemic cells obtained from 46 cases of B-type CLL, using the scanning electron microscope (SEM). All cases were defined by cytochemistry, immunological markers and transmission electron microscopy prior to SEM examination. B-CLL cells showed the well-recognized spectrum of surface architecture described in earlier studies. The majority of cells had moderate numbers of short microvilli, although in a minority, cells with relatively smooth surfaces predominated. In seven of the eight cases of PL-CLL, cells were villous in nature and in this respect similar to CLL cells; however, more cells with dense microvilli were seen. The prolymphocytic cells were recognized by their larger size and in 18 of the 19 cases of B-derived PLL, villous cells predominated. Two cases of T-derived PLL showed variable cell surface morphology ranging from smooth to moderately villous. It appears that B-PLL cells are most frequently villous and display more surface microvilli than B-CLL cells. B-prolymphocytes display the surface features regarded as characteristic for neoplastic B-cells as seen in patients with B-type lymphoma and leukaemia.

Adhesion and proliferation of OCT-1 osteoblast-like cells on micro- and nano-scale topography structured poly(L-lactide).

PubMed

Wan, Yuqing; Wang, Yong; Liu, Zhimin; Qu, Xue; Han, Buxing; Bei, Jianzhong; Wang, Shenguo

2005-07-01

The impact of the surface topography of polylactone-type polymer on cell adhesion was to be concerned because the micro-scale texture of a surface can provide a significant effect on the adhesion behavior of cells on the surface. Especially for the application of tissue engineering scaffold, the pore size could have an influence on cell in-growth and subsequent proliferation. Micro-fabrication technology was used to generate specific topography to investigate the relationship between the cells and surface. In this study the pits-patterned surfaces of polystyrene (PS) film with diameters 2.2 and 0.45 microm were prepared by phase-separation, and the corresponding scale islands-patterned PLLA surface was prepared by a molding technique using the pits-patterned PS as a template. The adhesion and proliferation behavior of OCT-1 osteoblast-like cells morphology on the pits- and islands-patterned surface were characterized by SEM observation, cell attachment efficiency measurement and MTT assay. The results showed that the cell adhesion could be enhanced on PLLA and PS surface with nano-scale and micro-scale roughness compared to the smooth surfaces of the PLLA and PS. The OCT-1 osteoblast-like cells could grow along the surface with two different size islands of PLLA and grow inside the micro-scale pits of the PS. However, the proliferation of cells on the micro- and nano-scale patterned surface has not been enhanced compared with the controlled smooth surface.

Solar cell modules with improved backskin and methods for forming same

DOEpatents

Hanoka, Jack I.

1998-04-21

A laminated solar cell module with a backskin layer that reduces the materials and labor required during the manufacturing process. The solar cell module includes a rigid front support layer formed of light transmitting material having first and second surfaces. A transparent encapsulant layer has a first surface disposed adjacent the second surface of the front support layer. A plurality of interconnected solar cells have a first surface disposed adjacent a second surface of the transparent encapsulant layer. The backskin layer is formed of a thermoplastic olefin, which includes first ionomer, a second ionomer, glass fiber, and carbon black. A first surface of the backskin layer is disposed adjacent a second surface of the interconnected solar cells. The transparent encapsulant layer and the backskin layer, in combination, encapsulate the interconnected solar cells. An end portion of the backskin layer can be wrapped around the edge of the module for contacting the first surface of the front support layer to form an edge seal. A laminated solar cell module with a backskin layer that reduces the materials and labor required during the manufacturing process. The solar cell module includes a rigid front support layer formed of light transmitting material having first and second surfaces. A transparent encapsulant layer has a first surface disposed adjacent the second surface of the front support layer. A plurality of interconnected solar cells have a first surface disposed adjacent a second surface of the transparent encapsulant layer. The backskin layer is formed of a thermoplastic olefin, which includes first ionomer, a second ionomer, glass fiber, and carbon black. A first surface of the backskin layer is disposed adjacent a second surface of the interconnected solar cells. The transparent encapsulant layer and the backskin layer, in combination, encapsulate the interconnected solar cells. An end portion of the backskin layer can be wrapped around the edge of the module for contacting the first surface of the front support layer to form an edge seal.

[Stimuli sensitive changes in electrical surface properties of soft membranes: from a synthesized polymer to a biological system].

PubMed

Makino, K

1997-01-01

The electrical surface properties of biological cells have been studied, which provided us with the fundamental knowledge about the cell surface. The change in shape or biological functions of cells may affect the surface properties and can be detected by electrokinetic measurements. Biological cell surfaces are covered with polysaccharide chains, some are charged and some are not. Some polysaccharides produce a hydrogel matrixes under a proper condition. We thus consider it reasonable that cell surface is approximated by a hydrogel surface. Electrophoretic mobility measurements are useful for studying the surface properties of biological cells suspended as colloidal particles in an electrolyte solution. The electro-osmotic velocity measurements on the other hand are advantageous to the study of the surface properties of slab-shaped biological systems such as membranes. This work was started with a hydrogel, as a model material. As a hydrogel, poly(N-isopropylacrylamide) poly(NIPAAm), abbreviated as hereafter, was chosen, because this hydrogel changes its volume depending on temperature. The dependence of the electrophoretic mobility of latex particles covered with poly(NIPAAm) hydrogel layer or of the electro-osmotic mobility on poly(NIPAAm) plate upon temperature and ionic strength of the dispersing medium was well explained with an electrophoretic mobility formula for "soft particles" developed by Ohshima. The electrokinetic measurements and the explanation of data with an electrophoretic mobility formula for "soft particles" give us information about the surface charge density and the "softness" of soft surfaces. On the basis of the findings with hydrogels, we have discussed the relationship between the changes in shape or function of the biological cells and the change in physicochemical surface properties using these measurements. To study the change in physicochemical properties of the cell surface caused by apoptosis, we have measured the electrophoretic mobilities of intact and apoptotic human promyelocytic leukemia cell lines, HL-60RG cells. We have also studied the differences observed in surface properties of malignant lymphosarcoma cell line, RAW117-P, and its variant, RAW117-H10, with a high metastatic property to the liver. In both cases, the cell surfaces became softer by the changes of biological functions. We have applied electrophoresis and electro-osmosis measurements to the study of the electrokinetic surface properties of rat basophilic leukemia cells, RBL cells. It was also found that the surface of Human umbilical vein endothelial cells, HUVEC, is considerably soft as compared with those of other biological cells we have studied before.

Chemical and Enzymatic Strategies for Bacterial and Mammalian Cell Surface Engineering.

PubMed

Bi, Xiaobao; Yin, Juan; Chen Guanbang, Ashley; Liu, Chuan-Fa

2018-06-07

The cell surface serves important functions such as the regulation of cell-cell and cell-environment interactions. The understanding and manipulation of the cell surface is important for a wide range of fundamental studies of cellular behavior and for biotechnological and medical applications. With the rapid advance of biology, chemistry and materials science, many strategies have been developed for the functionalization of bacterial and mammalian cell surfaces. Here, we review the recent development of chemical and enzymatic approaches to cell surface engineering with particular emphasis on discussing the advantages and limitations of each of these strategies. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of atomic force microscopy to microbial surfaces: from reconstituted cell surface layers to living cells.

PubMed

Dufrêne, Y F

2001-02-01

The application of atomic force microscopy (AFM) to probe the ultrastructure and physical properties of microbial cell surfaces is reviewed. The unique capabilities of AFM can be summarized as follows: imaging surface topography with (sub)nanometer lateral resolution; examining biological specimens under physiological conditions; measuring local properties and interaction forces. AFM is being used increasingly for: (i) visualizing the surface ultrastructure of microbial cell surface layers, including bacterial S-layers, purple membranes, porin OmpF crystals and fungal rodlet layers; (ii) monitoring conformational changes of individual membrane proteins; (iii) examining the morphology of bacterial biofilms, (iv) revealing the nanoscale structure of living microbial cells, including fungi, yeasts and bacteria, (v) mapping interaction forces at microbial surfaces, such as van der Waals and electrostatic forces, solvation forces, and steric/bridging forces; and (vi) probing the local mechanical properties of cell surface layers and of single cells.

Cell-surface engineering by a conjugation-and-release approach based on the formation and cleavage of oxime linkages upon mild electrochemical oxidation and reduction.

PubMed

Pulsipher, Abigail; Dutta, Debjit; Luo, Wei; Yousaf, Muhammad N

2014-09-01

We report a strategy to rewire cell surfaces for the dynamic control of ligand composition on cell membranes and the modulation of cell-cell interactions to generate three-dimensional (3D) tissue structures applied to stem-cell differentiation, cell-surface tailoring, and tissue engineering. We tailored cell surfaces with bioorthogonal chemical groups on the basis of a liposome-fusion and -delivery method to create dynamic, electroactive, and switchable cell-tissue assemblies through chemistry involving chemoselective conjugation and release. Each step to modify the cell surface: activation, conjugation, release, and regeneration, can be monitored and modulated by noninvasive, label-free analytical techniques. We demonstrate the utility of this methodology by the conjugation and release of small molecules to and from cell surfaces and by the generation of 3D coculture spheroids and multilayered cell tissues that can be programmed to undergo assembly and disassembly on demand. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cell/surface interactions on laser micro-textured titanium-coated silicon surfaces.

PubMed

Mwenifumbo, Steven; Li, Mingwei; Chen, Jianbo; Beye, Aboubaker; Soboyejo, Wolé

2007-01-01

This paper examines the effects of nano-scale titanium coatings, and micro-groove/micro-grid patterns on cell/surface interactions on silicon surfaces. The nature of the cellular attachment and adhesion to the coated/uncoated micro-textured surfaces was elucidated by the visualization of the cells and relevant cytoskeletal & focal adhesion proteins through scanning electron microscopy and immunofluorescence staining. Increased cell spreading and proliferation rates are observed on surfaces with 50 nm thick Ti coatings. The micro-groove geometries have been shown to promote contact guidance, which leads to reduced scar tissue formation. In contrast, smooth surfaces result in random cell orientations and the increased possibility of scar tissue formation. Immunofluorescence cell staining experiments also reveal that the actin stress fibers are aligned along the groove dimensions, with discrete focal adhesions occurring along the ridges, within the grooves and at the ends of the cell extensions. The implications of the observed cell/surface interactions are discussed for possible applications of silicon in implantable biomedical systems.

Surface engineering approaches to micropattern surfaces for cell-based assays.

PubMed

Falconnet, Didier; Csucs, Gabor; Grandin, H Michelle; Textor, Marcus

2006-06-01

The ability to produce patterns of single or multiple cells through precise surface engineering of cell culture substrates has promoted the development of cellular bioassays that provide entirely new insights into the factors that control cell adhesion to material surfaces, cell proliferation, differentiation and molecular signaling pathways. The ability to control shape and spreading of attached cells and cell-cell contacts through the form and dimension of the cell-adhesive patches with high precision is important. Commitment of stem cells to different specific lineages depends strongly on cell shape, implying that controlled microenvironments through engineered surfaces may not only be a valuable approach towards fundamental cell-biological studies, but also of great importance for the design of cell culture substrates for tissue engineering. Furthermore, cell patterning is an important tool for organizing cells on transducers for cell-based sensing and cell-based drug discovery concepts. From a material engineering standpoint, patterning approaches have greatly profited by combining microfabrication technologies, such as photolithography, with biochemical functionalization to present to the cells biological cues in spatially controlled regions where the background is rendered non-adhesive ("non-fouling") by suitable chemical modification. The focus of this review is on the surface engineering aspects of biologically motivated micropatterning of two-dimensional (flat) surfaces with the aim to provide an introductory overview and critical assessment of the many techniques described in the literature. In particular, the importance of non-fouling surface chemistries, the combination of hard and soft lithography with molecular assembly techniques as well as a number of less well known, but useful patterning approaches, including direct cell writing, are discussed.

Modulation of human multipotent and pluripotent stem cells using surface nanotopographies and surface-immobilised bioactive signals: A review.

PubMed

Wang, Peng-Yuan; Thissen, Helmut; Kingshott, Peter

2016-11-01

The ability to control the interactions of stem cells with synthetic surfaces is proving to be effective and essential for the quality of passaged stem cells and ultimately the success of regenerative medicine. The stem cell niche is crucial for stem cell self-renewal and differentiation. Thus, mimicking the stem cell niche, and here in particular the extracellular matrix (ECM), in vitro is an important goal for the expansion of stem cells and their applications. Here, surface nanotopographies and surface-immobilised biosignals have been identified as major factors that control stem cell responses. The development of tailored surfaces having an optimum nanotopography and displaying suitable biosignals is proposed to be essential for future stem cell culture, cell therapy and regenerative medicine applications. While early research in the field has been restricted by the limited availability of micro- and nanofabrication techniques, new approaches involving the use of advanced fabrication and surface immobilisation methods are starting to emerge. In addition, new cell types such as induced pluripotent stem cells (iPSCs) have become available in the last decade, but have not been fully understood. This review summarises significant advances in the area and focuses on the approaches that are aimed at controlling the behavior of human stem cells including maintenance of their self-renewal ability and improvement of their lineage commitment using nanotopographies and biosignals. More specifically, we discuss developments in biointerface science that are an important driving force for new biomedical materials and advances in bioengineering aiming at improving stem cell culture protocols and 3D scaffolds for clinical applications. Cellular responses revolve around the interplay between the surface properties of the cell culture substrate and the biomolecular composition of the cell culture medium. Determination of the precise role played by each factor, as well as the synergistic effects amongst the factors, all of which influence stem cell responses is essential for future developments. This review provides an overview of the current state-of-the-art in the design of complex material surfaces aimed at being the next generation of tools tailored for applications in cell culture and regenerative medicine. This review focuses on the effect of surface nanotopographies and surface-bound biosignals on human stem cells. Recently, stem cell research attracts much attention especially the induced pluripotent stem cells (iPSCs) and direct lineage reprogramming. The fast advance of stem cell research benefits disease treatment and cell therapy. On the other hand, surface property of cell adhered materials has been demonstrated very important for in vitro cell culture and regenerative medicine. Modulation of cell behavior using surfaces is costeffective and more defined. Thus, we summarise the recent progress of modulation of human stem cells using surface science. We believe that this review will capture a broad audience interested in topographical and chemical patterning aimed at understanding complex cellular responses to biomaterials. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

An AFM-based pit-measuring method for indirect measurements of cell-surface membrane vesicles

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

Zhang, Xiaojun; Department of Biotechnology, Nanchang University, Nanchang, Jiangxi 330031; Chen, Yuan

2014-03-28

Highlights: • Air drying induced the transformation of cell-surface membrane vesicles into pits. • An AFM-based pit-measuring method was developed to measure cell-surface vesicles. • Our method detected at least two populations of cell-surface membrane vesicles. - Abstract: Circulating membrane vesicles, which are shed from many cell types, have multiple functions and have been correlated with many diseases. Although circulating membrane vesicles have been extensively characterized, the status of cell-surface membrane vesicles prior to their release is less understood due to the lack of effective measurement methods. Recently, as a powerful, micro- or nano-scale imaging tool, atomic force microscopy (AFM)more » has been applied in measuring circulating membrane vesicles. However, it seems very difficult for AFM to directly image/identify and measure cell-bound membrane vesicles due to the similarity of surface morphology between membrane vesicles and cell surfaces. Therefore, until now no AFM studies on cell-surface membrane vesicles have been reported. In this study, we found that air drying can induce the transformation of most cell-surface membrane vesicles into pits that are more readily detectable by AFM. Based on this, we developed an AFM-based pit-measuring method and, for the first time, used AFM to indirectly measure cell-surface membrane vesicles on cultured endothelial cells. Using this approach, we observed and quantitatively measured at least two populations of cell-surface membrane vesicles, a nanoscale population (<500 nm in diameter peaking at ∼250 nm) and a microscale population (from 500 nm to ∼2 μm peaking at ∼0.8 μm), whereas confocal microscopy only detected the microscale population. The AFM-based pit-measuring method is potentially useful for studying cell-surface membrane vesicles and for investigating the mechanisms of membrane vesicle formation/release.« less

Effect of surface pre-treatments on biocompatibility of magnesium.

PubMed

Lorenz, Carla; Brunner, Johannes G; Kollmannsberger, Philip; Jaafar, Leila; Fabry, Ben; Virtanen, Sannakaisa

2009-09-01

This study reports the influence of Mg surface passivation on the survival rate of human HeLa cells and mouse fibroblasts in cell culture experiments. Polished samples of commercially pure Mg show high reactivity in the cell culture medium, leading to a pH shift in the alkaline direction, and therefore cell adhesion and survival is strongly impaired. Passivation of the Mg surface in 1M NaOH can strongly enhance cell survival. The best initial cell adhesion is observed for Mg samples incubated in simulated body fluid (M-SBF), which leads to the formation of a biomimetic, amorphous Ca/Mg-phosphate layer with high surface roughness. This surface layer, however, passivates and seals the Mg surface only partially. Subsequent Mg dissolution leads to a significantly stronger pH increase compared to NaOH-passivated samples, which prevents long-term cell survival. These results demonstrate that surface passivation with NaOH and M-SBF together with the associated changes of surface reactivity, chemistry and roughness provide a viable strategy to facilitate cell survival on otherwise non-biocompatible Mg surfaces.

HOS cell adhesion on Ti6Al4V surfaces texturized by laser engraving

NASA Astrophysics Data System (ADS)

Sandoval Amador, A.; Carreño Garcia, H.; Escobar Rivero, P.; Peña Ballesteros, D. Y.; Estupiñán Duran, H. A.

2016-02-01

The cell adhesion of the implant is determinate by the chemical composition, topography, wettability, surface energy and biocompatibility of the biomaterial. In this work the interaction between human osteosarcoma HOS cells and textured Ti6Al4V surfaces were evaluated. Ti6Al4V surfaces were textured using a CO2 laser in order to obtain circular spots on the surfaces. Test surfaces were uncoated (C1) used as a control surface, and surfaces with points obtained by laser engraving, with 1mm spacing (C2) and 0.5mm (C3). The HOS cells were cultured in RPMI-1640 medium with 10% fetal bovine serum and 1% antibiotics. No cells toxicity after one month incubation time occurred. The increased cell adhesion and cell spreading was observed after 1, 3 and 5 days without significant differences between the sample surfaces (C2 and C3) and control (uncoated) at the end of the experiment.

Investigation of surface endothelialization on biomedical nitinol (NiTi) alloy: Effects of surface micropatterning combined with plasma nanocoatings.

PubMed

Shen, Yang; Wang, Guixue; Chen, Liang; Li, Hao; Yu, Ping; Bai, Mengjun; Zhang, Qin; Lee, James; Yu, Qingsong

2009-11-01

Plasma nanocoated films with trimethylsilane-oxygen monomers showed outstanding biocompatibility in our previous studies. In this study, endothelialization on biomedical nitinol alloy surfaces was systematically investigated. Our study focuses on elucidating the effects of surface micropatternings with micropores and microgrooves combined with plasma nanocoating. Plasma nanocoatings with controlled thickness between 40 and 50 nm were deposited onto micropatterned nitinol surface in a direct current plasma reactor. Bovine aortic endothelial cells were cultured in vitro on these nitinol samples for 1, 3 and 5 days. It was found that rougher surfaces could enhance cell adhesion compared with the smoother surfaces; the surfaces patterned with micropores showed much more endothelialization than microgrooved surface after a 3 days culture. The cell culture results also showed that plasma nanocoatings significantly further increased cell proliferation and cell adhesion on the micropatterned nitinol surfaces, as compared with non-plasma nanocoated surface of nitinol samples. The surface micropatternings combined with plasma nanocoatings could improve the cell adhesion and accelerate surface endothelialization after implantation of intravascular stents, which is expected to reduce in-stent restenosis.

Enhanced Imaging of Specific Cell-Surface Glycosylation Based on Multi-FRET.

PubMed

Yuan, Baoyin; Chen, Yuanyuan; Sun, Yuqiong; Guo, Qiuping; Huang, Jin; Liu, Jianbo; Meng, Xiangxian; Yang, Xiaohai; Wen, Xiaohong; Li, Zenghui; Li, Lie; Wang, Kemin

2018-05-15

Cell-surface glycosylation contains abundant biological information that reflects cell physiological state, and it is of great value to image cell-surface glycosylation to elucidate its functions. Here we present a hybridization chain reaction (HCR)-based multifluorescence resonance energy transfer (multi-FRET) method for specific imaging of cell-surface glycosylation. By installing donors through metabolic glycan labeling and acceptors through aptamer-tethered nanoassemblies on the same glycoconjugate, intramolecular multi-FRET occurs due to near donor-acceptor distance. Benefiting from amplified effect and spatial flexibility of the HCR nanoassemblies, enhanced multi-FRET imaging of specific cell-surface glycosylation can be obtained. With this HCR-based multi-FRET method, we achieved obvious contrast in imaging of protein-specific GalNAcylation on 7211 cell surfaces. In addition, we demonstrated the general applicability of this method by visualizing the protein-specific sialylation on CEM cell surfaces. Furthermore, the expression changes of CEM cell-surface protein-specific sialylation under drug treatment was accurately monitored. This developed imaging method may provide a powerful tool in researching glycosylation functions, discovering biomarkers, and screening drugs.

Bacteria Hold Their Breath upon Surface Contact as Shown in a Strain of Escherichia coli, Using Dispersed Surfaces and Flow Cytometry Analysis

PubMed Central

Geng, Jing; Beloin, Christophe; Ghigo, Jean-Marc; Henry, Nelly

2014-01-01

Bacteria are ubiquitously distributed throughout our planet, mainly in the form of adherent communities in which cells exhibit specific traits. The mechanisms underpinning the physiological shift in surface-attached bacteria are complex, multifactorial and still partially unclear. Here we address the question of the existence of early surface sensing through implementation of a functional response to initial surface contact. For this purpose, we developed a new experimental approach enabling simultaneous monitoring of free-floating, aggregated and adherent cells via the use of dispersed surfaces as adhesive substrates and flow cytometry analysis. With this system, we analyzed, in parallel, the constitutively expressed GFP content of the cells and production of a respiration probe—a fluorescent reduced tetrazolium ion. In an Escherichia coli strain constitutively expressing curli, a major E. coli adhesin, we found that single cell surface contact induced a decrease in the cell respiration level compared to free-floating single cells present in the same sample. Moreover, we show here that cell surface contact with an artificial surface and with another cell caused reduction in respiration. We confirm the existence of a bacterial cell “sense of touch” ensuring early signalling of surface contact formation through respiration down modulation. PMID:25054429

Multijunction Solar Cell Technology for Mars Surface Applications

NASA Technical Reports Server (NTRS)

Stella, Paul M.; Mardesich, Nick; Ewell, Richard C.; Mueller, Robert L.; Endicter, Scott; Aiken, Daniel; Edmondson, Kenneth; Fetze, Chris

2006-01-01

Solar cells used for Mars surface applications have been commercial space qualified AM0 optimized devices. Due to the Martian atmosphere, these cells are not optimized for the Mars surface and as a result operate at a reduced efficiency. A multi-year program, MOST (Mars Optimized Solar Cell Technology), managed by JPL and funded by NASA Code S, was initiated in 2004, to develop tools to modify commercial AM0 cells for the Mars surface solar spectrum and to fabricate Mars optimized devices for verification. This effort required defining the surface incident spectrum, developing an appropriate laboratory solar simulator measurement capability, and to develop and test commercial cells modified for the Mars surface spectrum. This paper discusses the program, including results for the initial modified cells. Simulated Mars surface measurements of MER cells and Phoenix Lander cells (2007 launch) are provided to characterize the performance loss for those missions. In addition, the performance of the MER rover solar arrays is updated to reflect their more than two (2) year operation.

Antiadhesive Character of Mucin O-glycans at the Apical Surface of Corneal Epithelial Cells

PubMed Central

Sumiyoshi, Mika; Ricciuto, Jessica; Tisdale, Ann; Gipson, Ilene K.; Mantelli, Flavio; Argüeso, Pablo

2008-01-01

Purpose Prolonged contact of opposite mucosal surfaces, which occurs on the ocular surface, oral cavity, reproductive tract, and gut, requires a specialized apical cell surface that prevents adhesion. The purpose of this study was to evaluate the contribution of mucin O-glycans to the antiadhesive character of human corneal–limbal epithelial (HCLE) cells. Methods Mucin O-glycan biosynthesis in HCLE cells was disrupted by metabolic interference with benzyl-α-GalNAc. The cell surface mucin MUC16 and its carbohydrate epitope H185 were detected by immunofluorescence and Western blot. HCLE cell surface features were assessed by field emission scanning electron microscopy. Cell–cell adhesion assays were performed under static conditions and in a parallel plate laminar flow chamber. Results Benzyl-α-GalNAc disrupted the biosynthesis of O-glycans without affecting apomucin biosynthesis or cell surface morphology. Static adhesion assays showed that the apical surface of differentiated HCLE cells expressing MUC16 and H185 was more antiadhesive than undifferentiated HCLE cells, which lacked MUC16. Abrogation of mucin O-glycosylation in differentiated cultures with benzyl-α-GalNAc resulted in increased adhesion of applied corneal epithelial cells and corneal fibroblasts. The antiadhesive effect of mucin O-glycans was further demonstrated by fluorescence video microscopy in dynamic flow adhesion assays. Cationized ferritin labeling of the cell surface indicated that anionic repulsion did not contribute to the antiadhesive character of the apical surface. Conclusions These results indicate that epithelial O-glycans contribute to the antiadhesive properties of cell surface–associated mucins in corneal epithelial cells and suggest that alterations in mucin O-glycosylation are involved in the pathology of drying mucosal diseases (e.g., dry eye). PMID:18172093

Particle compositions with a pre-selected cell internalization mode

NASA Technical Reports Server (NTRS)

Ferrari, Mauro (Inventor); Decuzzi, Paolo (Inventor)

2012-01-01

A method of formulating a particle composition having a pre-selected cell internalization mode involves selecting a target cell having surface receptors and obtaining particles that have i) surface moieties, that have an affinity for or are capable of binding to the surface receptors of the cell and ii) a preselected shape, where a surface distribution of the surface moieties on the particles and the shape of the particles are effective for the pre-selected cell internalization mode.

TGF-β induces surface LAP expression on murine CD4 T cells independent of Foxp3 induction.

PubMed

Oida, Takatoku; Weiner, Howard L

2010-11-24

It has been reported that human FOXP3(+) CD4 Tregs express GARP-anchored surface latency-associated peptide (LAP) after activation, based on the use of an anti-human LAP mAb. Murine CD4 Foxp3(+) Tregs have also been reported to express surface LAP, but these studies have been hampered by the lack of suitable anti-mouse LAP mAbs. We generated anti-mouse LAP mAbs by immunizing TGF-β(-/-) animals with a mouse Tgfb1-transduced P3U1 cell line. Using these antibodies, we demonstrated that murine Foxp3(+) CD4 Tregs express LAP on their surface. In addition, retroviral transduction of Foxp3 into mouse CD4(+)CD25(-) T cells induced surface LAP expression. We then examined surface LAP expression after treating CD4(+)CD25(-) T cells with TGF-β and found that TGF-β induced surface LAP not only on T cells that became Foxp3(+) but also on T cells that remained Foxp3(-) after TGF-β treatment. GARP expression correlated with the surface LAP expression, suggesting that surface LAP is GARP-anchored also in murine T cells. Unlike human CD4 T cells, surface LAP expression on mouse CD4 T cells is controlled by Foxp3 and TGF-β. Our newly described anti-mouse LAP mAbs will provide a useful tool for the investigation and functional analysis of T cells that express LAP on their surface.

Real-time and label-free analysis of binding thermodynamics of carbohydrate-protein interactions on unfixed cancer cell surfaces using a QCM biosensor

PubMed Central

Li, Xueming; Song, Siyu; Shuai, Qi; Pei, Yihan; Aastrup, Teodor; Pei, Yuxin; Pei, Zhichao

2015-01-01

A novel approach to the study of binding thermodynamics and kinetics of carbohydrate-protein interactions on unfixed cancer cell surfaces using a quartz crystal microbalance (QCM) biosensor was developed, in which binding events take place at the cell surface, more closely mimicking a biologically relevant environment. In this study, colon adenocarcinoma cells (KM-12) and ovary adenocarcinoma cells (SKOV-3) grew on the optimized polystyrene-coated biosensor chip without fixation. The association and dissociation between the cell surface carbohydrates and a range of lectins, including WGA, Con A, UEA-I, GS-II, PNA and SBA, were monitored in real time and without label for evaluation of cell surface glycosylation. Furthermore, the thermodynamic and kinetic parameters of the interaction between lectins and cell surface glycan were studied, providing detailed information about the interactions, such as the association rate constant, dissociation rate constant, affinity constant, as well as the changes of entropy, enthalpy and Gibbs free energy. This application provides an insight into the cell surface glycosylation and the complex molecular recognition on the intact cell surface, which may have impacts on disease diagnosis and drug discovery. PMID:26369583

Surface design of antibody-immobilized thermoresponsive cell culture dishes for recovering intact cells by low-temperature treatment.

PubMed

Kobayashi, Jun; Hayashi, Masaki; Ohno, Takahiro; Nishi, Masanori; Arisaka, Yoshinori; Matsubara, Yoshinori; Kakidachi, Hiroshi; Akiyama, Yoshikatsu; Yamato, Masayuki; Horii, Akihiro; Okano, Teruo

2014-11-01

Antibody-immobilized thermoresponsive poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) [poly(IPAAm-co-CIPAAm)]-grafted cell culture surfaces were designed to enhance both the initial adhesion of weakly adhering cells and the ability of cells to detach in response to low temperature through the regulation of affinity binding between immobilized antibodies and antigens on the cellular surface. Ty-82 cells and neonatal normal human dermal fibroblasts (NHDFs), which express CD90 on the cell surface, adhered to anti-CD90 antibody-immobilized thermoresponsive surfaces at 37°C, a condition at which the grafted thermoresponsive polymer chains shrank. Adherent Ty-82 cells were detached from the surfaces by lowering the temperature to 20°C and applying external forces, such as pipetting, whereas cultured NHDF sheets spontaneously detached themselves from the surface in response to reduced temperature alone. When the temperature was decreased to 20°C, the swelling of grafted thermoresponsive polymer chains weakened the affinity binding between immobilized antibody and antigen on the cells due to the increasing steric hindrance of the polymer chains around the antigen-recognition site of the immobilized antibodies. No contamination was detected on cells harvested from covalently immobilized antibodies on the culture surfaces by low-temperature treatment, whereas a carryover of the antibody and avidin from the avidin-biotin binding surface was observed. Furthermore, the initial adhesion of adipose tissue-derived cells, which adhere weakly to PIPAAm-grafted surfaces, was enhanced on the antibody-immobilized thermoresponsive surfaces. © 2013 Wiley Periodicals, Inc.

Stack configurations for tubular solid oxide fuel cells

DOEpatents

Armstrong, Timothy R.; Trammell, Michael P.; Marasco, Joseph A.

2010-08-31

A fuel cell unit includes an array of solid oxide fuel cell tubes having porous metallic exterior surfaces, interior fuel cell layers, and interior surfaces, each of the tubes having at least one open end; and, at least one header in operable communication with the array of solid oxide fuel cell tubes for directing a first reactive gas into contact with the porous metallic exterior surfaces and for directing a second reactive gas into contact with the interior surfaces, the header further including at least one busbar disposed in electrical contact with at least one surface selected from the group consisting of the porous metallic exterior surfaces and the interior surfaces.

Morphological Observations of Mesenchymal Stem Cell Adhesion to a Nanoperiodic-Structured Titanium Surface Patterned Using Femtosecond Laser Processing

NASA Astrophysics Data System (ADS)

Oya, Kei; Aoki, Shun; Shimomura, Kazunori; Sugita, Norihiko; Suzuki, Kenji; Nakamura, Norimasa; Fujie, Hiromichi

2012-12-01

It is known that the adhesive and anisotropic properties of cell-derived biomaterials are affected by micro- or nanoscale structures processed on culture surfaces. In the present study, the femtosecond laser processing technique was used to scan a laser beam at an intensity of approximately the ablation threshold level on a titanium surface for nanoscale processing. Microscopy observation revealed that the processed titanium exhibited a periodic-patterned groove structure at the surface; the width and depth of the groove were 292 ±50 and 99 ±31 nm, respectively, and the periodic pitch of the groove was 501 ±100 nm. Human synovium-derived mesenchymal stem cells were cultured on the surface at a cell density of 3.0×103 cells/cm2 after 4 cell passages. For comparison, the cells were also cultured on a nonprocessed titanium surface under the condition identical to that of the processed surface. Results revealed that the duration for cell attachment to the surface was markedly reduced on the processed titanium as compared with the nonprocessed titanium. Moreover, on the processed titanium, cell extension area significantly increased while cell orientation was aligned along the direction of the periodic grooves. These results suggest that the femtosecond laser processing improves the adhesive and anisotropic properties of cells by producing the nanoperiodic structure on titanium culture surfaces.

The role of surface implant treatments on the biological behavior of SaOS-2 osteoblast-like cells. An in vitro comparative study.

PubMed

Conserva, Enrico; Menini, Maria; Ravera, Giambattista; Pera, Paolo

2013-08-01

The aim of this study was an in vitro comparison of osteoblast adhesion, proliferation and differentiation related to six dental implants with different surface characteristics, and to determine if the interaction between cells and implant is influenced by surface structure and chemical composition. Six types of implants were tested, presenting four different surface treatments: turned, sandblasted, acid-etched, anodized. The implant macro- and microstructure were analyzed using SEM, and the surface chemical composition was investigated using energy-dispersive X-ray analysis. SaOS-2 osteoblasts were used for the evaluation of cell adhesion and proliferation by SEM, and cell viability in contact with the various surfaces was determined using cytotoxicity MTT assays. Alkaline phosphatase (ALP) enzymatic activity in contact with the six surfaces was evaluated. Data relative to MTT assay and ALP activity were statistically analyzed using Kruskal-Wallis not parametric test and Nemenyi-Damico-Wolfe-Dunn post hoc test. All the implants tested supported cell adhesion, proliferation and differentiation, revealing neither organic contaminants nor cytotoxicity effects. The industrial treatments investigated changed the implant surface microscopic aspect and SaOS-2 cell morphology appeared to be influenced by the type of surface treatment at 6, 24, and 72 h of growth. SaOS-2 cells spread more rapidly on sandblasted surfaces. Turned surfaces showed the lowest cell proliferation at SEM observation. Sandblasted surfaces showed the greatest ALP activity values per cell, followed by turned surfaces (P < 0.05). On the base of this in vitro investigation, differently surfaced implants affected osteoblast morphology, adhesion, proliferation, and differentiation. Sandblasted surfaces promoted the most suitable osteoblast behavior. © 2012 John Wiley & Sons A/S.

Studying Cancer Stem Cell Dynamics on PDMS Surfaces for Microfluidics Device Design

PubMed Central

Zhang, Weijia; Choi, Dong Soon; Nguyen, Yen H.; Chang, Jenny; Qin, Lidong

2013-01-01

This systematic study clarified a few interfacial aspects of cancer cell phenotypes on polydimethylsiloxane (PDMS) substrates and indicated that the cell phenotypic equilibrium greatly responds to cell-to-surface interactions. We demonstrated that coatings of fibronectin, bovine serum albumin (BSA), or collagen with or without oxygen-plasma treatments of the PDMS surfaces dramatically impacted the phenotypic equilibrium of breast cancer stem cells, while the variations of the PDMS elastic stiffness had much less such effects. Our results showed that the surface coatings of collagen and fibronectin on PDMS maintained breast cancer cell phenotypes to be nearly identical to the cultures on commercial polystyrene Petri dishes. The surface coating of BSA provided a weak cell-substrate adhesion that stimulated the increase in stem-cell-like subpopulation. Our observations may potentially guide surface modification approaches to obtain specific cell phenotypes. PMID:23900274

The Endogenous GRP78 Interactome in Human Head and Neck Cancers: A Deterministic Role of Cell Surface GRP78 in Cancer Stemness.

PubMed

Chen, Hsin-Ying; Chang, Joseph Tung-Chieh; Chien, Kun-Yi; Lee, Yun-Shien; You, Guo-Rung; Cheng, Ann-Joy

2018-01-11

Cell surface glucose regulated protein 78 (GRP78), an endoplasmic reticulum (ER) chaperone, was suggested to be a cancer stem cell marker, but the influence of this molecule on cancer stemness is poorly characterized. In this study, we developed a mass spectrometry platform to detect the endogenous interactome of GRP78 and investigated its role in cancer stemness. The interactome results showed that cell surface GRP78 associates with multiple molecules. The influence of cell population heterogeneity of head and neck cancer cell lines (OECM1, FaDu, and BM2) according to the cell surface expression levels of GRP78 and the GRP78 interactome protein, Progranulin, was investigated. The four sorted cell groups exhibited distinct cell cycle distributions, asymmetric/symmetric cell divisions, and different relative expression levels of stemness markers. Our results demonstrate that cell surface GRP78 promotes cancer stemness, whereas drives cells toward a non-stemlike phenotype when it chaperones Progranulin. We conclude that cell surface GRP78 is a chaperone exerting a deterministic influence on cancer stemness.

Nanotextured polymer substrates show enhanced cancer cell isolation and cell culture

NASA Astrophysics Data System (ADS)

Islam, Muhymin; Sajid, Adeel; Arif Iftakher Mahmood, M.; Motasim Bellah, Mohammad; Allen, Peter B.; Kim, Young-Tae; Iqbal, Samir M.

2015-06-01

Detection of circulating tumor cells (CTCs) in the early stages of cancer is a great challenge because of their exceedingly small concentration. There are only a few approaches sensitive enough to differentiate tumor cells from the plethora of other cells in a sample like blood. In order to detect CTCs, several antibodies and aptamers have already shown high affinity. Nanotexture can be used to mimic basement membrane to further enhance this affinity. This article reports an approach to fabricate nanotextured polydimethylsiloxane (PDMS) substrates using micro reactive ion etching (micro-RIE). Three recipes were used to prepare nanotextured PDMS using oxygen and carbon tetrafluoride. Micro-RIE provided better control on surface properties. Nanotexturing improved the affinity of PDMS surfaces to capture cancer cells using surface immobilized aptamers against cell membrane overexpressed with epidermal growth factor receptors. In all cases, nanotexture of PDMS increased the effective surface area by creating nanoscale roughness on the surface. Nanotexture also enhanced the growth rate of cultured cells compared to plain surfaces. A comparison among the three nanotextured surfaces demonstrated an almost linear relationship between the surface roughness and density of captured tumor cells. The nanotextured PDMS mimicked biophysical environments for cells to grow faster. This can have many implications in microfluidic platforms used for cell handling.

Dendritic Cell-Based Genetic Immunotherapy for Ovarian Cancer

DTIC Science & Technology

2007-12-01

CAR. CD40 is a surface marker expressed by DCs that plays a crucial role in their maturation and subsequent stimulation of T cells. DC infection with... surface . CD40 is a cell surface marker expressed by DCs, is crucial for their maturation and the subsequent activation of the immune system by the DCs...cell surface . CD40 is a cell surface marker expressed by DCs, is crucial for their maturation and the subsequent activation of the immune system by the

Back surface reflectors for solar cells

NASA Technical Reports Server (NTRS)

Chai, A. T.

1980-01-01

Sample solar cells were fabricated to study the effects of various back surface reflectors on the device performance. They are typical 50 micrometers thick, space quality, silicon solar cells except for variations of the back contact configuration. The back surfaces of the sample cells are polished to a mirror like finish, and have either conventional full contacts or grid finger contacts. Measurements and evaluation of various metallic back surface reflectors, as well as cells with total internal reflection, are presented. Results indicate that back surface reflectors formed using a grid finger back contact are more effective reflectors than cells with full back metallization and that Au, Ag, or Cu are better back surface reflector metals than Al.

Surface free energy predominates in cell adhesion to hydroxyapatite through wettability.

PubMed

Nakamura, Miho; Hori, Naoko; Ando, Hiroshi; Namba, Saki; Toyama, Takeshi; Nishimiya, Nobuyuki; Yamashita, Kimihiro

2016-05-01

The initial adhesion of cells to biomaterials is critical in the regulation of subsequent cell behaviors. The purpose of this study was to investigate a mechanism through which the surface wettability of biomaterials can be improved and determine the effects of biomaterial surface characteristics on cellular behaviors. We investigated the surface characteristics of various types of hydroxyapatite after sintering in different atmospheres and examined the effects of various surface characteristics on cell adhesion to study cell-biomaterial interactions. Sintering atmosphere affects the polarization capacity of hydroxyapatite by changing hydroxide ion content and grain size. Compared with hydroxyapatite sintered in air, hydroxyapatite sintered in saturated water vapor had a higher polarization capacity that increased surface free energy and improved wettability, which in turn accelerated cell adhesion. We determined the optimal conditions of hydroxyapatite polarization for the improvement of surface wettability and acceleration of cell adhesion. Copyright © 2016 Elsevier B.V. All rights reserved.

Mapping cell surface adhesion by rotation tracking and adhesion footprinting

NASA Astrophysics Data System (ADS)

Li, Isaac T. S.; Ha, Taekjip; Chemla, Yann R.

2017-03-01

Rolling adhesion, in which cells passively roll along surfaces under shear flow, is a critical process involved in inflammatory responses and cancer metastasis. Surface adhesion properties regulated by adhesion receptors and membrane tethers are critical in understanding cell rolling behavior. Locally, adhesion molecules are distributed at the tips of membrane tethers. However, how functional adhesion properties are globally distributed on the individual cell’s surface is unknown. Here, we developed a label-free technique to determine the spatial distribution of adhesive properties on rolling cell surfaces. Using dark-field imaging and particle tracking, we extract the rotational motion of individual rolling cells. The rotational information allows us to construct an adhesion map along the contact circumference of a single cell. To complement this approach, we also developed a fluorescent adhesion footprint assay to record the molecular adhesion events from cell rolling. Applying the combination of the two methods on human promyelocytic leukemia cells, our results surprisingly reveal that adhesion is non-uniformly distributed in patches on the cell surfaces. Our label-free adhesion mapping methods are applicable to the variety of cell types that undergo rolling adhesion and provide a quantitative picture of cell surface adhesion at the functional and molecular level.

Nanowall formation by maskless wet-etching on a femtosecond laser irradiated silicon surface

NASA Astrophysics Data System (ADS)

Lee, Siwoo; Jo, Kukhyun; Keum, Hee-sung; Chae, Sangmin; Kim, Yonghyeon; Choi, Jiyeon; Lee, Hyun Hwi; Kim, Hyo Jung

2018-04-01

We found that micro-cells surrounded by nanowalls can be formed by a maskless wet-etching process on Si (100) surfaces possessing Laser Induced Periodic Surface Structure (LIPSS) by femtosecond laser irradiation. The LIPSS process could produce periodic one-dimensional micron scale ripples on a Si surface, which could be developed into micro-cells by a subsequent etching process. The solution etching conditions strongly affected both the micro-cell and nanowall shapes such as the height and the thickness of nanowalls. The tetramethylammonium hydroxide solution created thin nanowalls and the resulting micro-cells with a well-flattened bottom while the KOH solution formed thick walls and incomplete micro-cells. The bottoms of micro-cells surrounded by the nanowalls were considerably flat with a 3.10 nm surface roughness. A pentacene layer was deposited on the micro-cells of a Si surface to evaluate the film properties by grazing incidence wide angle x-ray scattering measurements. The pentacene film on the micro-cell Si surface showed a strong film phase, which was comparable to the film phase grown on the atomically flat Si surface.

Surface-engineered substrates for improved human pluripotent stem cell culture under fully defined conditions.

PubMed

Saha, Krishanu; Mei, Ying; Reisterer, Colin M; Pyzocha, Neena Kenton; Yang, Jing; Muffat, Julien; Davies, Martyn C; Alexander, Morgan R; Langer, Robert; Anderson, Daniel G; Jaenisch, Rudolf

2011-11-15

The current gold standard for the culture of human pluripotent stem cells requires the use of a feeder layer of cells. Here, we develop a spatially defined culture system based on UV/ozone radiation modification of typical cell culture plastics to define a favorable surface environment for human pluripotent stem cell culture. Chemical and geometrical optimization of the surfaces enables control of early cell aggregation from fully dissociated cells, as predicted from a numerical model of cell migration, and results in significant increases in cell growth of undifferentiated cells. These chemically defined xeno-free substrates generate more than three times the number of cells than feeder-containing substrates per surface area. Further, reprogramming and typical gene-targeting protocols can be readily performed on these engineered surfaces. These substrates provide an attractive cell culture platform for the production of clinically relevant factor-free reprogrammed cells from patient tissue samples and facilitate the definition of standardized scale-up friendly methods for disease modeling and cell therapeutic applications.

Tuning cell adhesion on polymeric and nanocomposite surfaces: Role of topography versus superhydrophobicity.

PubMed

Zangi, Sepideh; Hejazi, Iman; Seyfi, Javad; Hejazi, Ehsan; Khonakdar, Hossein Ali; Davachi, Seyed Mohammad

2016-06-01

Development of surface modification procedures which allow tuning the cell adhesion on the surface of biomaterials and devices is of great importance. In this study, the effects of different topographies and wettabilities on cell adhesion behavior of polymeric surfaces are investigated. To this end, an improved phase separation method was proposed to impart various wettabilities (hydrophobic and superhydrophobic) on polypropylene surfaces. Surface morphologies and compositions were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cell culture was conducted to evaluate the adhesion of 4T1 mouse mammary tumor cells. It was found that processing conditions such as drying temperature is highly influential in cell adhesion behavior due to the formation of an utterly different surface topography. It was concluded that surface topography plays a more significant role in cell adhesion behavior rather than superhydrophobicity since the nano-scale topography highly inhibited the cell adhesion as compared to the micro-scale topography. Such cell repellent behavior could be very useful in many biomedical devices such as those in drug delivery and blood contacting applications as well as biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Do cell surface trafficking impairments account for variable cell surface sodium iodide symporter levels in breast cancer?

PubMed Central

Beyer, S.J.; Jimenez, R.E.; Shapiro, C.L.; Cho, J.Y.; Jhiang, S.M.

2009-01-01

The Na+/I- symporter (NIS) is a transmembrane glycoprotein that mediates iodide uptake into thyroid follicular cells and serves as the molecular basis of radioiodine imaging and therapy for thyroid cancer patients. The finding that NIS protein is present in 80-90% of breast tumors suggests that breast cancer patients may also benefit from NIS-mediated radionuclide imaging and targeted therapy. However, only 17-25% of NIS-positive breast tumors have detectable radionuclide uptake activity. The discrepancy between NIS expression and radionuclide uptake activity is most likely contributed by variable cell surface NIS protein levels. Apart from the prevalent view that NIS cell surface trafficking impairments account for the variability, our current study proposes that differential levels of NIS expression may also account for variable cell surface NIS levels among breast tumors. We address the need to confirm the identity of intracellular NIS staining to reveal the mechanisms underlying variable cell surface NIS levels. In addition, we warrant a quantitative correlation between cell surface NIS levels and radionuclide uptake activity in patients such that the cell surface NIS levels required for radionuclide imaging can be defined and the defects impairing NIS activity can be recognized. PMID:18500672

Nano-patterned SU-8 surface using nanosphere-lithography for enhanced neuronal cell growth

NASA Astrophysics Data System (ADS)

Kim, Eunhee; Yoo, Seung-Jun; Kim, Eunjung; Kwon, Tae-Hwan; Zhang, Li; Moon, Cheil; Choi, Hongsoo

2016-04-01

Mimicking the nanoscale surface texture of the extracellular matrix can affect the regulation of cellular behavior, including adhesion, differentiation, and neurite outgrowth. In this study, SU-8-based polymer surfaces with well-ordered nanowell arrays were fabricated using nanosphere lithography with polystyrene nanoparticles. We show that the SU-8 surface with nanowells resulted in similar neuronal development of rat pheochromocytoma (PC12) cells compared with an unpatterned poly-L-lysine (PLL)-coated SU-8 surface. Additionally, even after soaking the substrate in cell culture medium for two weeks, cells on the nanowell SU-8 surface showed long-term neurite outgrowth compared to cells on the PLL-coated SU-8 surface. The topographical surface modification of the nanowell array demonstrates potential as a replacement for cell adhesive material coatings such as PLL, for applications requiring long-term use of polymer-based implantable devices.

Phosphatidylserine as an anchor for plasminogen and its plasminogen receptor, Histone H2B, to the macrophage surface

PubMed Central

DAS, R.; PLOW, E. F.

2013-01-01

Summary Background Plasminogen (Plg) binding to cell surface Plg receptors (Plg-Rs) on the surface of macrophages facilitates Plg activation and migration of these cells. Histone H2B (H2B) acts as a Plg-R and its cell surface expression is upregulated when monocytes are differentiated to macrophages via a pathway dependent on L-type Ca2+ channels and intracellular Ca2+. Objectives We sought to investigate the mechanism by which H2B, a protein without a transmembrane domain, is retained on themacrophage surface. Methods THP-1 monocytoid cells were induced to differentiate with interferon gamma + Vitamin D3 or to undergo apoptosis by treatment with camptothecin. Flow cytometry and cell surface biotinylation followed by Western blotting were used to measure the interrelationship between Plg binding, cell surface expression of H2B and outermembrane exposure of phosphatidylserine (PS). Results H2B interacted directly with PS via an electrostatic interaction. Anti-PS or PS binding proteins, annexin V and protein S, diminished H2B interaction with PS on the surface of differentiated or apoptotic cells and these same reagents inhibited Plg binding to these cells. L-type Ca2+ channels played a significant role in PS exposure, H2B surface expression and Plg binding induced either by differentiation or apoptosis. Conclusions These data suggest that H2B tethers to the surface of cells by interacting with PS on differentiated or apoptotic monocytoid cells. L-type Ca2+ channels regulate PS exposure on the surface of these cells. The exposed PS interacts directly with H2B and hence provides sites for Plg to bind to. PMID:21040449

Role of Glucosyltransferase B in Interactions of Candida albicans with Streptococcus mutans and with an Experimental Pellicle on Hydroxyapatite Surfaces ▿ †

PubMed Central

Gregoire, S.; Xiao, J.; Silva, B. B.; Gonzalez, I.; Agidi, P. S.; Klein, M. I.; Ambatipudi, K. S.; Rosalen, P. L.; Bauserman, R.; Waugh, R. E.; Koo, H.

2011-01-01

Candida albicans and mutans streptococci are frequently detected in dental plaque biofilms from toddlers afflicted with early childhood caries. Glucosyltransferases (Gtfs) secreted by Streptococcus mutans bind to saliva-coated apatite (sHA) and to bacterial surfaces, synthesizing exopolymers in situ, which promote cell clustering and adherence to tooth enamel. We investigated the potential role Gtfs may play in mediating the interactions between C. albicans SC5314 and S. mutans UA159, both with each other and with the sHA surface. GtfB adhered effectively to the C. albicans yeast cell surface in an enzymatically active form, as determined by scintillation spectroscopy and fluorescence imaging. The glucans formed on the yeast cell surface were more susceptible to dextranase than those synthesized in solution or on sHA and bacterial cell surfaces (P < 0.05), indicating an elevated α-1,6-linked glucose content. Fluorescence imaging revealed that larger numbers of S. mutans cells bound to C. albicans cells with glucans present on their surface than to yeast cells without surface glucans (uncoated). The glucans formed in situ also enhanced C. albicans interactions with sHA, as determined by a novel single-cell micromechanical method. Furthermore, the presence of glucan-coated yeast cells significantly increased the accumulation of S. mutans on the sHA surface (versus S. mutans incubated alone or mixed with uncoated C. albicans; P < 0.05). These data reveal a novel cross-kingdom interaction that is mediated by bacterial GtfB, which readily attaches to the yeast cell surface. Surface-bound GtfB promotes the formation of a glucan-rich matrix in situ and may enhance the accumulation of S. mutans on the tooth enamel surface, thereby modulating the development of virulent biofilms. PMID:21803906

The effects of pulsed electromagnetic field (PEMF) on osteoblast-like cells cultured on titanium and titanium-zirconium surfaces.

PubMed

Atalay, Belir; Aybar, Buket; Ergüven, Mine; Emes, Yusuf; Bultan, Özgür; Akça, Kivanç; Yalçin, Serhat; Baysal, Uğur; Işsever, Halim; Çehreli, Murat Cavit; Bilir, Ayhan

2013-11-01

Commercially pure Ti, together with Ti Ni, Ti-6Al-4V, and Ti-6Al-7Nb alloys, are among the materials currently being used for this purpose. Titanium-zirconium (TiZr) has been developed that allows SLActive surface modification and that has comparable or better mechanical strength and improved biocompatibility compared with existing Ti alloys. Furthermore, approaches have targeted making the implant surface more hydrophilic, as with the Straumann SLActive surface, a modification of the SLA surface. The aim of this study is to evaluate the effects of pulsed electromagnetic field (PEMF) to the behavior of neonatal rat calvarial osteoblast-like cells cultured on commercially pure titanium (cpTi) and titanium-zirconium alloy (TiZr) discs with hydrophilic surface properties. Osteoblast cells were cultured on titanium and TiZr discs, and PEMF was applied. Cell proliferation rates, cell numbers, cell viability rates, alkaline phosphatase, and midkine (MK) levels were measured at 24 and 72 hours. At 24 hours, the number of cells was significantly higher in the TiZr group. At 72 hours, TiZr had a significantly higher number of cells when compared to SLActive, SLActive + PEMF, and machine surface + PEMF groups. At 24 hours, cell proliferation was significantly higher in the TiZr group than SLActive and TiZr + PEMF group. At 72 hours, TiZr group had higher proliferation rate than machine surface and TiZr + PEMF. Cell proliferation in the machine surface group was lower than both SLActive + PEMF and machine surface + PEMF. MK levels of PEMF-treated groups were lower than untreated groups for 72 hours. Our findings conclude that TiZr surfaces are similar to cpTi surfaces in terms of biocompatibility. However, PEMF application has a higher stimulative effect on cells cultured on cpTi surfaces when compared to TiZr.

Measurement of surface recombination velocity for silicon solar cells using a scanning electron microscope with pulsed beam

NASA Technical Reports Server (NTRS)

Daud, T.; Cheng, L. J.

1981-01-01

The role of surface recombination velocity in the design and fabrication of silicon solar cells is discussed. A scanning electron microscope with pulsed electron beam was used to measure this parameter of silicon surfaces. It is shown that the surface recombination velocity, s, increases by an order of magnitude when an etched surface degrades, probably as a result of environmental reaction. A textured front-surface-field cell with a high-low junction near the surface shows the effect of minority carrier reflection and an apparent reduction of s, whereas a tandem-junction cell shows an increasing s value. Electric fields at junction interfaces in front-surface-field and tandem-junction cells acting as minority carrier reflectors or sinks tend to alter the value of effective surface recombination velocity for different beam penetration depths. A range of values of s was calculated for different surfaces.

Nanotextured PDMS Substrates for Enhanced Roughness and Aptamer Immobilization for Cancer Cell Capture

NASA Astrophysics Data System (ADS)

Islam, Muhymin; Mahmood, Arif; Bellah, Md.; Kim, Young-Tae; Iqbal, Samir

2014-03-01

Detection of circulating tumor cells (CTCs) in the early stages of cancer is requires very sensitive approach. Nanotextured polydimethylsiloxane (PDMS) substrates were fabricated by micro reactive ion etching (Micro-RIE) to have better control on surface morphology and to improve the affinity of PDMS surfaces to capture cancer cells using surface immobilized aptamers. The aptamers were specific to epidermal growth factor receptors (EGFR) present in cell membranes, and overexpressed in tumor cells. We also investigated the effect of nano-scale features on cell capturing by implementing various surfaces of different roughnesses. Three different recipes were used to prepare nanotextured PDMS by micro-RIE using oxygen (O2) and carbon tetrafluoride (CF4). The measured average roughness of three nanotextured PDMS surfaces were found to impact average densities of captured cells. In all cases, nanotextured PDMS facilitated cell capturing possibly due to increased effective surface area of roughened substrates at nanoscale. It was also observed that cell capture efficiency was higher for higher surface roughness. The nanotextured PDMS substrates are thus useful for cancer cytology devices.

Estimating intercellular surface tension by laser-induced cell fusion.

PubMed

Fujita, Masashi; Onami, Shuichi

2011-12-01

Intercellular surface tension is a key variable in understanding cellular mechanics. However, conventional methods are not well suited for measuring the absolute magnitude of intercellular surface tension because these methods require determination of the effective viscosity of the whole cell, a quantity that is difficult to measure. In this study, we present a novel method for estimating the intercellular surface tension at single-cell resolution. This method exploits the cytoplasmic flow that accompanies laser-induced cell fusion when the pressure difference between cells is large. Because the cytoplasmic viscosity can be measured using well-established technology, this method can be used to estimate the absolute magnitudes of tension. We applied this method to two-cell-stage embryos of the nematode Caenorhabditis elegans and estimated the intercellular surface tension to be in the 30-90 µN m(-1) range. Our estimate was in close agreement with cell-medium surface tensions measured at single-cell resolution.

Atomic force microscopy – looking at mechanosensors on the cell surface

PubMed Central

Heinisch, Jürgen J.; Lipke, Peter N.; Beaussart, Audrey; El Kirat Chatel, Sofiane; Dupres, Vincent; Alsteens, David; Dufrêne, Yves F.

2012-01-01

Summary Living cells use cell surface proteins, such as mechanosensors, to constantly sense and respond to their environment. However, the way in which these proteins respond to mechanical stimuli and assemble into large complexes remains poorly understood at the molecular level. In the past years, atomic force microscopy (AFM) has revolutionized the way in which biologists analyze cell surface proteins to molecular resolution. In this Commentary, we discuss how the powerful set of advanced AFM techniques (e.g. live-cell imaging and single-molecule manipulation) can be integrated with the modern tools of molecular genetics (i.e. protein design) to study the localization and molecular elasticity of individual mechanosensors on the surface of living cells. Although we emphasize recent studies on cell surface proteins from yeasts, the techniques described are applicable to surface proteins from virtually all organisms, from bacteria to human cells. PMID:23077172

Physical-mechanical image of the cell surface on the base of AFM data in contact mode

NASA Astrophysics Data System (ADS)

Starodubtseva, M. N.; Starodubtsev, I. E.; Yegorenkov, N. I.; Kuzhel, N. S.; Konstantinova, E. E.; Chizhik, S. A.

2017-10-01

Physical and mechanical properties of the cell surface are well-known markers of a cell state. The complex of the parameters characterizing the cell surface properties, such as the elastic modulus (E), the parameters of adhesive (Fa), and friction (Ff) forces can be measured using atomic force microscope (AFM) in a contact mode and form namely the physical-mechanical image of the cell surface that is a fundamental element of the cell mechanical phenotype. The paper aims at forming the physical-mechanical images of the surface of two types of glutaraldehyde-fixed cancerous cells (human epithelial cells of larynx carcinoma, HEp-2c cells, and breast adenocarcinoma, MCF-7 cells) based on the data obtained by AFM in air and revealing the basic difference between them. The average values of friction, elastic and adhesive forces, and the roughness of lateral force maps, as well as dependence of the fractal dimension of lateral force maps on Z-scale factor have been studied. We have revealed that the response of microscale areas of the HEp-2c cell surface having numerous microvilli to external mechanical forces is less expressed and more homogeneous in comparison with the response of MCF-7 cell surface.

Comparison of the fouling release properties of hydrophobic fluorinated and hydrophilic PEGylated block copolymer surfaces: attachment strength of the diatom Navicula and the green alga Ulva.

PubMed

Krishnan, Sitaraman; Wang, Nick; Ober, Christopher K; Finlay, John A; Callow, Maureen E; Callow, James A; Hexemer, Alexander; Sohn, Karen E; Kramer, Edward J; Fischer, Daniel A

2006-05-01

To understand the role of surface wettability in adhesion of cells, the attachment of two different marine algae was studied on hydrophobic and hydrophilic polymer surfaces. Adhesion of cells of the diatom Navicula and sporelings (young plants) of the green macroalga Ulva to an underwater surface is mainly by interactions between the surface and the adhesive exopolymers, which the cells secrete upon settlement and during subsequent colonization and growth. Two types of block copolymers, one with poly(ethylene glycol) side-chains and the other with liquid crystalline, fluorinated side-chains, were used to prepare the hydrophilic and hydrophobic surfaces, respectively. The formation of a liquid crystalline smectic phase in the latter inhibited molecular reorganization at the surface, which is generally an issue when a highly hydrophobic surface is in contact with water. The adhesion strength was assessed by the fraction of settled cells (Navicula) or biomass (Ulva) that detached from the surface in a water flow channel with a wall shear stress of 53 Pa. The two species exhibited opposite adhesion behavior on the same sets of surfaces. While Navicula cells released more easily from hydrophilic surfaces, Ulva sporelings showed higher removal from hydrophobic surfaces. This highlights the importance of differences in cell-surface interactions in determining the strength of adhesion of cells to substrates.

Rho-associated kinase (ROCK) inhibition reverses low cell activity on hydrophobic surfaces.

PubMed

Tian, Yu Shun; Kim, Hyun Jung; Kim, Hyun-Man

2009-08-28

Hydrophobic polymers do not offer an adequate scaffold surface for cells to attach, migrate, proliferate, and differentiate. Thus, hydrophobic scaffolds for tissue engineering have traditionally been physicochemically modified to enhance cellular activity. However, modifying the surface by chemical or physical treatment requires supplementary engineering procedures. In the present study, regulation of a cell signal transduction pathway reversed the low cellular activity on a hydrophobic surface without surface modification. Inhibition of Rho-associated kinase (ROCK) by Y-27632 markedly enhanced adhesion, migration, and proliferation of osteoblastic cells cultured on a hydrophobic polystyrene surface. ROCK inhibition regulated cell-cycle-related molecules on the hydrophobic surface. This inhibition also decreased expression of the inhibitors of cyclin-dependent kinases such as p21(cip1) and p27(kip1) and increased expression of cyclin A and D. These results indicate that defective cellular activity on the hydrophobic surface can be reversed by the control of a cell signal transduction pathway without physicochemical surface modification.

Accelerated cell-sheet recovery from a surface successively grafted with polyacrylamide and poly(N-isopropylacrylamide).

PubMed

Akiyama, Yoshikatsu; Kikuchi, Akihiko; Yamato, Masayuki; Okano, Teruo

2014-08-01

A double polymeric nanolayer consisting of poly(N-isopropylacrylamide) (PIPAAm) and hydrophilic polyacrylamide (PAAm) was deposited on tissue culture polystyrene (TCPS) surfaces using electron beam irradiation to form a new temperature-responsive cell culture surface in which the basal hydrophilic PAAm component in the double polymeric layer promotes the hydration of the upper PIPAAm layer and induces rapid cell detachment compared to a conventional temperature-responsive cell culture surface, PIPAAm-grafted TCPS (PIPAAm-TCPS). Take-off angle-dependent X-ray photoelectron spectroscopy spectral analysis demonstrated that the grafted PIPAAm and PAAm components were located in the upper and basal regions of the double polymeric layer, respectively, suggesting that the double polymeric layer forms an inter-penetrating-network-like structure with PAAm at the basal portion of the PIPAAm grafted chains. The wettability of the temperature-responsive cell culture surfaces with the double polymeric layer tended to be more hydrophilic, with an increase in the basal PAAm graft density at a constant PIPAAm graft density. However, when the graft densities of the upper PIPAAm and basal PAAm were optimized, the resulting temperature-responsive cell culture surface with the double polymeric layer exhibited rapid cell detachment while maintaining cell adhesive character comparable to that of PIPAAm-TCPS. The cell adhesive character was altered from cell-adhesive to cell-repellent with increasing PAAm or PIPAAm graft density. The cell adhesive character of the temperature-responsive cell culture surfaces was relatively consistent with their contact angles. These results strongly suggest that the basal PAAm surface properties affect the degree of hydration and dehydration of the subsequently grafted PIPAAm. In addition, the roles of the hydrophilic component in accelerating cell detachment are further discussed in terms of the mobility of the grafted PIPAAm chains. Applications of this insight might be useful for designing temperature-responsive cell culture surfaces for achieving efficient cell culture and quick target cell detachment. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Ketone isosteres of 2-N-acetamidosugars as substrates for metabolic cell surface engineering

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

Hang, Howard C.; Bertozzi, Carolyn R.

2000-08-22

Novel chemical reactivity can be engendered on cell surfaces by the metabolic incorporation of unnatural sugars into cell surface glycoconjuagtes. 2-N-Acetamido sugars such as GalNAc and GlcNAc are abundant components of cell surface glycoconjugates, and hence attractive targets for metabolic cell surface engineering. Here we report (1) the synthesis of isosteric analogs bearing a ketone group in place of the N-acetamido group, and (2) evaluation of their metabolic incorporation into mammalian cell surface glycans. A ketone isostere of GalNAc was metabolized by CHO cells through the salvage pathway and delivered to O-linked glycoproteins on the cell surface. Its residence atmore » the core position of O-linked glycans is suggested by studies with a-benzyl GalNAc, an inhibitor of O-linked oligosaccharide extension. A mutant CHO cell line lacking endogenous UDP-GalNAc demonstrated enhanced metabolism of the GalNAc analog, suggesting that competition with native intermediates might limits enzymatic transformation in mammalian cells. A ketone isostere of GlcNAc could not be detected on CHO or human cell surfaces after incubation. Thus, the enzymes in the GlcNAc salvage pathway might be less permissive of unnatural substrates than those comprising the GalNAc salvage pathway. Alternatively, high levels of endogenous GlcNAc derivatives might compete with the ketone isostere and prevent its incorporation into oligosaccharides.« less

Calreticulin is expressed on the cell surface of activated human peripheral blood T lymphocytes in association with major histocompatibility complex class I molecules.

PubMed

Arosa, F A; de Jesus, O; Porto, G; Carmo, A M; de Sousa, M

1999-06-11

Calreticulin is an endoplasmic reticulum resident molecule known to be involved in the folding and assembly of major histocompatibility complex (MHC) class I molecules. In the present study, expression of calreticulin was analyzed in human peripheral blood T lymphocytes. Pulse-chase experiments in [35S]methionine-labeled T cell blasts showed that calreticulin was associated with several proteins in the endoplasmic reticulum and suggested that it was expressed at the cell surface. Indeed, the 60-kDa calreticulin was labeled by cell surface biotinylation and precipitated from the surface of activated T cells together with a protein with an apparent molecular mass of 46 kDa. Cell surface expression of calreticulin by activated T lymphocytes was further confirmed by immunofluorescence and flow cytometry, studies that showed that both CD8+ and CD4+ T cells expressed calreticulin in the plasma membrane. Low amounts of cell surface calreticulin were detected in resting T lymphocytes. By sequential immunoprecipitation using the conformation independent monoclonal antibody HC-10, we provided evidence that the cell surface 46-kDa protein co-precipitated with calreticulin is unfolded MHC I. These results show for the first time that after T cell activation, significant amounts of calreticulin are expressed on the T cell surface, where they are found in physical association with a pool of beta2-free MHC class I molecules.

Altering textural properties of fermented milk by using surface-engineered Lactococcus lactis.

PubMed

Tarazanova, Mariya; Huppertz, Thom; Kok, Jan; Bachmann, Herwig

2018-05-09

Lactic acid bacteria are widely used for the fermentation of dairy products. While bacterial acidification rates, proteolytic activity and the production of exopolysaccharides are known to influence textural properties of fermented milk products, little is known about the role of the microbial surface on microbe-matrix interactions in dairy products. To investigate how alterations of the bacterial cell surface affect fermented milk properties, 25 isogenic Lactococcus lactis strains that differed with respect to surface charge, hydrophobicity, cell chaining, cell-clumping, attachment to milk proteins, pili expression and EPS production were used to produce fermented milk. We show that overexpression of pili increases surface hydrophobicity of various strains from 3-19% to 94-99%. A profound effect of different cell surface properties was an altered spatial distribution of the cells in the fermented product. Aggregated cells tightly fill the cavities of the protein matrix, while chaining cells seem to be localized randomly. A positive correlation was found between pili overexpression and viscosity and gel hardness of fermented milk. Gel hardness also positively correlated with clumping of cells in the fermented milk. Viscosity of fermented milk was also higher when it was produced with cells with a chaining phenotype or with cells that overexpress exopolysaccharides. Our results show that alteration of cell surface morphology affects textural parameters of fermented milk and cell localization in the product. This is indicative of a cell surface-dependent potential of bacterial cells as structure elements in fermented foods. © 2018 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

The cell surface environment for pathogen recognition and entry.

PubMed

Stow, Jennifer L; Condon, Nicholas D

2016-04-01

The surface of mammalian cells offers an interface between the cell interior and its surrounding milieu. As part of the innate immune system, macrophages have cell surface features optimised for probing and sampling as they patrol our tissues for pathogens, debris or dead cells. Their highly dynamic and constantly moving cell surface has extensions such as lamellipodia, filopodia and dorsal ruffles that help detect pathogens. Dorsal ruffles give rise to macropinosomes for rapid, high volume non-selective fluid sampling, receptor internalisation and plasma membrane turnover. Ruffles can also generate phagocytic cups for the receptor-mediated uptake of pathogens or particles. The membrane lipids, actin cytoskeleton, receptors and signalling proteins that constitute these cell surface domains are discussed. Although the cell surface is designed to counteract pathogens, many bacteria, viruses and other pathogens have evolved to circumvent or hijack these cell structures and their underlying machinery for entry and survival. Nevertheless, these features offer important potential for developing vaccines, drugs and preventative measures to help fight infection.

Photovoltaic cell and production thereof

DOEpatents

Narayanan, Srinivasamohan [Gaithersburg, MD; Kumar, Bikash [Bangalore, IN

2008-07-22

An efficient photovoltaic cell, and its process of manufacture, is disclosed wherein the back surface p-n junction is removed from a doped substrate having an oppositely doped emitter layer. A front surface and edges and optionally the back surface periphery are masked and a back surface etch is performed. The mask is not removed and acts as an anti-reflective coating, a passivating agent, or both. The photovoltaic cell retains an untextured back surface whether or not the front is textured and the dopant layer on the back surface is removed to enhance the cell efficiency. Optionally, a back surface field is formed.

Cytocompatibility of Direct Laser Interference-patterned Titanium Surfaces for Implants.

PubMed

Hartjen, Philip; Nada, Ola; Silva, Thiago Gundelwein; Precht, Clarissa; Henningsen, Anders; Holthaus, Marzellus GROßE; Gulow, Nikolai; Friedrich, Reinhard E; Hanken, Henning; Heiland, Max; Zwahr, Christoph; Smeets, Ralf; Jung, Ole

2017-01-01

In an effort to generate titanium surfaces for implants with improved osseointegration, we used direct laser interference patterning (DLIP) to modify the surface of pure titanium grade 4 of four different structures. We assessed in vitro cytoxicity and cell attachment, as well as the viability and proliferation of cells cultured directly on the surfaces. Attachment of the cells to the modified surfaces was comparably good compared to that of cells on grit-blasted and acid-etched reference titanium surfaces. In concordance with this, viability and proliferation of the cells directly cultured on the specimens were similar on all the titanium surfaces, regardless of the laser modification, indicating good cytocompatibility. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Pseudomonas aeruginosa attachment on QCM-D sensors: the role of cell and surface hydrophobicities.

PubMed

Marcus, Ian M; Herzberg, Moshe; Walker, Sharon L; Freger, Viatcheslav

2012-04-17

While biofilms are ubiquitous in nature, the mechanism by which they form is still poorly understood. This study investigated the process by which bacteria deposit and, shortly after, attach irreversibly to surfaces by reorienting to create a stronger interaction, which leads to biofilm formation. A model for attachment of Pseudomonas aeruginosa was developed using a quartz crystal microbalance with dissipation monitoring (QCM-D) technology, along with a fluorescent microscope and camera to monitor kinetics of adherence of the cells over time. In this model, the interaction differs depending on the force that dominates between the viscous, inertial, and elastic loads. P. aeruginosa, grown to the midexponential growth phase (hydrophilic) and stationary phase (hydrophobic) and two different surfaces, silica (SiO(2)) and polyvinylidene fluoride (PVDF), which are hydrophilic and hydrophobic, respectively, were used to test the model. The bacteria deposited on both of the sensor surfaces, though on the silica surface the cells reached a steady state where there was no net increase in deposition of bacteria, while the quantity of cells depositing on the PVDF surface continued to increase until the end of the experiments. The change in frequency and dissipation per cell were both positive for each overtone (n), except when the cells and surface are both hydrophilic. In the model three factors, specifically, viscous, inertial, and elastic loads, contribute to the change in frequency and dissipation at each overtone when a cell deposits on a sensor. On the basis of the model, hydrophobic cells were shown to form an elastic connection to either surface, with an increase of elasticity at higher overtones. At lower overtones, hydrophilic cells depositing on the hydrophobic surface were shown to also be elastic, but as the overtone increases the connection between the cells and sensor becomes more viscoelastic. In the case of hydrophilic cells interacting with the hydrophilic surface, the connection is viscous at each overtone measured. It could be inferred that the transformation of the viscoelasticity of the cell-surface connection is due to changes in the orientation of the cells to the surface, which allow the bacteria to attach irreversibly and begin biofilm formation. © 2012 American Chemical Society

Dual-responsive surfaces modified with phenylboronic acid-containing polymer brush to reversibly capture and release cancer cells.

PubMed

Liu, Hongliang; Li, Yingying; Sun, Kang; Fan, Junbing; Zhang, Pengchao; Meng, Jingxin; Wang, Shutao; Jiang, Lei

2013-05-22

Artificial stimuli-responsive surfaces that can mimic the dynamic function of living systems have attracted much attention. However, there exist few artificial systems capable of responding to dual- or multistimulation as the natural system does. Herein, we synthesize a pH and glucose dual-responsive surface by grafting poly(acrylamidophenylboronic acid) (polyAAPBA) brush from aligned silicon nanowire (SiNW) array. The as-prepared surface can reversibly capture and release targeted cancer cells by precisely controlling pH and glucose concentration, exhibiting dual-responsive AND logic. In the presence of 70 mM glucose, the surface is pH responsive, which can vary from a cell-adhesive state to a cell-repulsive state by changing the pH from 6.8 to 7.8. While keeping the pH at 7.8, the surface becomes glucose responsive--capturing cells in the absence of glucose and releasing cells by adding 70 mM glucose. Through simultaneously changing the pH and glucose concentration from pH 6.8/0 mM glucose to pH 7.8/70 mM glucose, the surface is dual responsive with the capability to switch between cell capture and release for at least 5 cycles. The cell capture and release process on this dual-responsive surface is noninvasive with cell viability higher than 95%. Moreover, topographical interaction between the aligned SiNW array and cell protrusions greatly amplifies the responsiveness and accelerates the response rate of the dual-responsive surface between cell capture and release. The responsive mechanism of the dual-responsive surface is systematically studied using a quartz crystal microbalance, which shows that the competitive binding between polyAAPBA/sialic acid and polyAAPBA/glucose contributes to the dual response. Such dual-responsive surface can significantly impact biomedical and biological applications including cell-based diagnostics, in vivo drug delivery, etc.

Chemical and physical effects on the adhesion, maturation, and survival of monocytes, macrophages, and foreign body giant cells

NASA Astrophysics Data System (ADS)

Collier, Terry Odell, III

Injury caused by biomedical device implantation initiates inflammatory and wound healing responses. Cells migrate to the site of injury to degrade bacteria and toxins, create new vasculature, and form new and repair injured tissue. Blood-proteins rapidly adsorb onto the implanted material surface and express adhesive ligands which mediate cell adhesion on the material surface. Monocyte-derived macrophages and multi-nucleated foreign body giant cells adhere to the surface and degrade the surface of the material. Due to the role of macrophage and foreign body giant cell on material biocompatibility and biostability, the effects of surface chemistry, surface topography and specific proteins on the maturation and survival of monocytes, macrophages and foreign body giant cells has been investigated. Novel molecularly designed materials were used to elucidate the dynamic interactions which occur between inflammatory cells, proteins and surfaces. The effect of protein and protein adhesion was investigated using adhesive protein depleted serum conditions on RGD-modified and silane modified surfaces. The effects of surface chemistry were investigated using temperature responsive surfaces of poly (N-isopropylacrylamide) and micropatterned surfaces of N-(2 aminoethyl)-3-aminopropyltrimethoxysilane regions on an interpenetrating polymer network of polyacrylamide and poly(ethylene glycol). The physical effects were investigated using polyimide scaffold materials and polyurethane materials with surface modifying end groups. The depletion of immunoglobulin G caused decreased levels of macrophage adhesion, foreign body giant cell formation and increased levels of apoptosis. The temporal nature of macrophage adhesion was observed with changing effectiveness of adherent cell detachment with time, which correlated to increased expression of beta1 integrin receptors on detached macrophages with time. The limited ability of the micropatterned surface, polyimide scaffold and surface modified polyurethane materials to control macrophage adhesion indicates the complexity of macrophage adhesion and protein adsorption onto a surface. These studies have indicated components and adhesive mechanisms which can be utilized to create materials with enhanced resistance to macrophage adhesion and/or degradative abilities.

Quantification of surface tension and internal pressure generated by single mitotic cells

NASA Astrophysics Data System (ADS)

Fischer-Friedrich, Elisabeth; Hyman, Anthony A.; Jülicher, Frank; Müller, Daniel J.; Helenius, Jonne

2014-08-01

During mitosis, adherent cells round up, by increasing the tension of the contractile actomyosin cortex while increasing the internal hydrostatic pressure. In the simple scenario of a liquid cell interior, the surface tension is related to the local curvature and the hydrostatic pressure difference by Laplace's law. However, verification of this scenario for cells requires accurate measurements of cell shape. Here, we use wedged micro-cantilevers to uniaxially confine single cells and determine confinement forces while concurrently determining cell shape using confocal microscopy. We fit experimentally measured confined cell shapes to shapes obeying Laplace's law with uniform surface tension and find quantitative agreement. Geometrical parameters derived from fitting the cell shape, and the measured force were used to calculate hydrostatic pressure excess and surface tension of cells. We find that HeLa cells increase their internal hydrostatic pressure excess and surface tension from ~ 40 Pa and 0.2 mNm-1 during interphase to ~ 400 Pa and 1.6 mNm-1 during metaphase. The method introduced provides a means to determine internal pressure excess and surface tension of rounded cells accurately and with minimal cellular perturbation, and should be applicable to characterize the mechanical properties of various cellular systems.

Microbial cell surface characteristics: Elucidating attachment/detachment using hydrophobicity and electrokinetic measurements

EPA Science Inventory

The surface properties of microorganisms play an important role in their behavior within the environment. Electrophoretic mobility and cell surface hydrophobicity of bacterial cells influence their initial interaction with surfaces and mediate their stability within an aqueous su...

Osteogenic potential of in situ TiO2 nanowire surfaces formed by thermal oxidation of titanium alloy substrate

NASA Astrophysics Data System (ADS)

Tan, A. W.; Ismail, R.; Chua, K. H.; Ahmad, R.; Akbar, S. A.; Pingguan-Murphy, B.

2014-11-01

Titanium dioxide (TiO2) nanowire surface structures were fabricated in situ by a thermal oxidation process, and their ability to enhance the osteogenic potential of primary osteoblasts was investigated. Human osteoblasts were isolated from nasal bone and cultured on a TiO2 nanowires coated substrate to assess its in vitro cellular interaction. Bare featureless Ti-6Al-4V substrate was used as a control surface. Initial cell adhesion, cell proliferation, cell differentiation, cell mineralization, and osteogenic related gene expression were examined on the TiO2 nanowire surfaces as compared to the control surfaces after 2 weeks of culturing. Cell adhesion and cell proliferation were assayed by field emission scanning electron microscope (FESEM) and Alamar Blue reduction assay, respectively. The nanowire surfaces promoted better cell adhesion and spreading than the control surface, as well as leading to higher cell proliferation. Our results showed that osteoblasts grown onto the TiO2 nanowire surfaces displayed significantly higher production levels of alkaline phosphatase (ALP), extracellular (ECM) mineralization and genes expression of runt-related transcription factor (Runx2), bone sialoprotein (BSP), ostoepontin (OPN) and osteocalcin (OCN) compared to the control surfaces. This suggests the potential use of such surface modification on Ti-6Al-4V substrates as a promising means to improve the osteointegration of titanium based implants.

Remote Control of Tissue Interactions via Engineered Photo-switchable Cell Surfaces

NASA Astrophysics Data System (ADS)

Luo, Wei; Pulsipher, Abigail; Dutta, Debjit; Lamb, Brian M.; Yousaf, Muhammad N.

2014-09-01

We report a general cell surface molecular engineering strategy via liposome fusion delivery to create a dual photo-active and bio-orthogonal cell surface for remote controlled spatial and temporal manipulation of microtissue assembly and disassembly. Cell surface tailoring of chemoselective functional groups was achieved by a liposome fusion delivery method and quantified by flow cytometry and characterized by a new cell surface lipid pull down mass spectrometry strategy. Dynamic co-culture spheroid tissue assembly in solution and co-culture tissue multilayer assembly on materials was demonstrated by an intercellular photo-oxime ligation that could be remotely cleaved and disassembled on demand. Spatial and temporal control of microtissue structures containing multiple cell types was demonstrated by the generation of patterned multilayers for controlling stem cell differentiation. Remote control of cell interactions via cell surface engineering that allows for real-time manipulation of tissue dynamics may provide tools with the scope to answer fundamental questions of cell communication and initiate new biotechnologies ranging from imaging probes to drug delivery vehicles to regenerative medicine, inexpensive bioreactor technology and tissue engineering therapies.

Glycobiology of the cell surface: Its debt to cell electrophoresis 1940-65.

PubMed

Cook, Geoffrey M W

2016-06-01

This Review describes how in the period 1940-1959 cell electrophoresis (in the earlier literature often referred to as 'microelectrophoresis') was used to explore the surface chemistry of cells. Using the erythrocyte as a suitable model for the study of biological membranes, the early investigators were agreed on the presence of negatively charged groups at the surface of this cell. The contemporary dogma was that these were phosphate groups associated with phospholipids. Work in the 1960s, particularly on changes in the electrokinetic properties of erythrocytes following treatment with proteolytic enzymes, lead to the realization that the negatively charged groups at the red cell surface are predominantly due to sialic acids carried on glycoproteins. It quickly became apparent from cell electrophoresis that sialic acids have a ubiquitous presence on the surface of animal cells. This finding required that any complete model of the plasma membrane must include glycosylated molecules at the cell periphery, thus laying the foundations for the field termed 'Glycobiology of the Cell Surface'. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cell density-dependent differential proliferation of neural stem cells on omnidirectional nanopore-arrayed surface.

PubMed

Cha, Kyoung Je; Kong, Sun-Young; Lee, Ji Soo; Kim, Hyung Woo; Shin, Jae-Yeon; La, Moonwoo; Han, Byung Woo; Kim, Dong Sung; Kim, Hyun-Jung

2017-10-12

Recently, the importance of surface nanotopography in the determination of stem cell fate and behavior has been revealed. In the current study, we generated polystyrene cell-culture dishes with an omnidirectional nanopore arrayed surface (ONAS) (diameter: 200 nm, depth: 500 nm, center-to-center distance: 500 nm) and investigated the effects of nanotopography on rat neural stem cells (NSCs). NSCs cultured on ONAS proliferated better than those on the flat surface when cell density was low and showed less spontaneous differentiation during proliferation in the presence of mitogens. Interestingly, NSCs cultured on ONAS at clonal density demonstrated a propensity to generate neurospheres, whereas those on the flat surface migrated out, proliferated as individuals, and spread out to attach to the surface. However, the differential patterns of proliferation were cell density-dependent since the distinct phenomena were lost when cell density was increased. ONAS modulated cytoskeletal reorganization and inhibited formation of focal adhesion, which is generally observed in NSCs grown on flat surfaces. ONAS appeared to reinforce NSC-NSC interaction, restricted individual cell migration and prohibited NSC attachment to the nanopore surface. These data demonstrate that ONAS maintains NSCs as undifferentiated while retaining multipotency and is a better topography for culturing low density NSCs.

Investigation of the Cell Surface Proteome of Human Periodontal Ligament Stem Cells

PubMed Central

Xiong, Jimin; Menicanin, Danijela; Marino, Victor

2016-01-01

The present study examined the cell surface proteome of human periodontal ligament stem cells (PDLSC) compared to human fibroblasts. Cell surface proteins were prelabelled with CyDye before processing to extract the membrane lysates, which were separated using 2D electrophoresis. Selected differentially expressed protein “spots” were identified using Mass spectrometry. Four proteins were selected for validation: CD73, CD90, Annexin A2, and sphingosine kinase 1 previously associated with mesenchymal stem cells. Flow cytometric analysis found that CD73 and CD90 were highly expressed by human PDLSC and gingival fibroblasts but not by keratinocytes, indicating that these antigens could be used as potential markers for distinguishing between mesenchymal cells and epithelial cell populations. Annexin A2 was also found to be expressed at low copy number on the cell surface of human PDLSC and gingival fibroblasts, while human keratinocytes lacked any cell surface expression of Annexin A2. In contrast, sphingosine kinase 1 expression was detected in all the cell types examined using immunocytochemical analysis. These proteomic studies form the foundation to further define the cell surface protein expression profile of PDLSC in order to better characterise this cell population and help develop novel strategies for the purification of this stem cell population. PMID:27579043

Investigation of the Cell Surface Proteome of Human Periodontal Ligament Stem Cells.

PubMed

Xiong, Jimin; Menicanin, Danijela; Zilm, Peter S; Marino, Victor; Bartold, P Mark; Gronthos, Stan

2016-01-01

The present study examined the cell surface proteome of human periodontal ligament stem cells (PDLSC) compared to human fibroblasts. Cell surface proteins were prelabelled with CyDye before processing to extract the membrane lysates, which were separated using 2D electrophoresis. Selected differentially expressed protein "spots" were identified using Mass spectrometry. Four proteins were selected for validation: CD73, CD90, Annexin A2, and sphingosine kinase 1 previously associated with mesenchymal stem cells. Flow cytometric analysis found that CD73 and CD90 were highly expressed by human PDLSC and gingival fibroblasts but not by keratinocytes, indicating that these antigens could be used as potential markers for distinguishing between mesenchymal cells and epithelial cell populations. Annexin A2 was also found to be expressed at low copy number on the cell surface of human PDLSC and gingival fibroblasts, while human keratinocytes lacked any cell surface expression of Annexin A2. In contrast, sphingosine kinase 1 expression was detected in all the cell types examined using immunocytochemical analysis. These proteomic studies form the foundation to further define the cell surface protein expression profile of PDLSC in order to better characterise this cell population and help develop novel strategies for the purification of this stem cell population.

Antibody-immobilized column for quick cell separation based on cell rolling.

PubMed

Mahara, Atsushi; Yamaoka, Tetsuji

2010-01-01

Cell separation using methodological standards that ensure high purity is a very important step in cell transplantation for regenerative medicine and for stem cell research. A separation protocol using magnetic beads has been widely used for cell separation to isolate negative and positive cells. However, not only the surface marker pattern, e.g., negative or positive, but also the density of a cell depends on its developmental stage and differentiation ability. Rapid and label-free separation procedures based on surface marker density are the focus of our interest. In this study, we have successfully developed an antiCD34 antibody-immobilized cell-rolling column, that can separate cells depending on the CD34 density of the cell surfaces. Various conditions for the cell-rolling column were optimized including graft copolymerization, and adjustment of the column tilt angle, and medium flow rate. Using CD34-positive and -negative cell lines, the cell separation potential of the column was established. We observed a difference in the rolling velocities between CD34-positive and CD34-negative cells on antibody-immobilized microfluidic device. Cell separation was achieved by tilting the surface 20 degrees and the increasing medium flow. Surface marker characteristics of the isolated cells in each fraction were analyzed using a cell-sorting system, and it was found that populations containing high density of CD34 were eluted in the delayed fractions. These results demonstrate that cells with a given surface marker density can be continuously separated using the cell rolling column.

Separation and characterization of effective demulsifying substances from surface of Alcaligenes sp. S-XJ-1 and its application in water-in-kerosene emulsion.

PubMed

Huang, Xiangfeng; Peng, Kaiming; Feng, Yi; Liu, Jia; Lu, Lijun

2013-07-01

The main goal of this work was to analyze the effect of surface substances on demulsifying capability of the demulsifying strain Alcaligenes sp. S-XJ-1. The demulsifying substances were successfully separated from the cell surface with dichloromethane-alkali treatment, and exhibited 67.5% of the demulsification ratio for water-in-kerosene emulsions at a dosage of 356mg/L. FT-IR, TLC and ESI-MS analysis confirmed the presence of a carbohydrate-protein-lipid complex in the demulsifying substances with the major molecular ions from mass-to-charge ratio (m/z) 165 to 814. After the substances separated, the cell morphology changed from aggregated to dispersed, and the concentration of cell surface functional groups decreased. Cell surface hydrophobicity and the ability of cell adhesion to hydrophobic surface of the treated cells was also reduced compared with original cell. It was proved that the demulsifying substances had a significant effect on cell surface properties and accordingly with demulsifying capability of Alcaligenes sp. S-XJ-1. Copyright © 2013 Elsevier Ltd. All rights reserved.

Study of wettability and cell viability of H implanted stainless steel

NASA Astrophysics Data System (ADS)

Shafique, Muhammad Ahsan; Ahmad, Riaz; Rehman, Ihtesham Ur

2018-03-01

In the present work, the effect of hydrogen ion implantation on surface wettability and biocompatibility of stainless steel is investigated. Hydrogen ions are implanted in the near-surface of stainless steel to facilitate hydrogen bonding at different doses with constant energy of 500 KeV, which consequently improve the surface wettability. Treated and untreated sample are characterized for surface wettability, incubation of hydroxyapatite and cell viability. Contact angle (CA) study reveals that surface wettability increases with increasing H-ion dose. Raman spectroscopy shows that precipitation of hydroxyapatite over the surface increase with increasing dose of H-ions. Cell viability study using MTT assay describes improved cell viability in treated samples as compared to the untreated sample. It is found that low dose of H-ions is more effective for cell proliferation and the cell count decreases with increasing ion dose. Our study demonstrates that H ion implantation improves the surface wettability and biocompatibility of stainless steel.

Surface nanoporosity has a greater influence on osteogenic and bacterial cell adhesion than crystallinity and wettability

NASA Astrophysics Data System (ADS)

Rodriguez-Contreras, Alejandra; Guadarrama Bello, Dainelys; Nanci, Antonio

2018-07-01

There has been much emphasis on the influence of crystallinity and wettability for modulating cell activity, particularly for bone biomaterials. In this context, we have generated titanium oxide layers with similar mesoporous topography and surface roughness but with amorphous or crystalline oxide layers and differential wettability. We then investigated their influence on the behavior of MC3T3 osteoblastic and bacterial cells. There was no difference in cell adhesion, spreading and growth on amorphous and crystalline surfaces. The number of focal adhesions was similar, however, cells on the amorphous surface exhibited a higher frequency of mature adhesions. The crystallinity of the surface layers also had no bearing on bacterial adhesion. While it cannot be excluded that surface crystallinity, roughness and wettability contribute to some degree to determining cell behavior, our data suggest that physical characteristics of surfaces represent the major determinant.

Nanostructured Polyaniline Coating on ITO Glass Promotes the Neurite Outgrowth of PC 12 Cells by Electrical Stimulation.

PubMed

Wang, Liping; Huang, Qianwei; Wang, Jin-Ye

2015-11-10

A conducting polymer polyaniline (PANI) with nanostructure was synthesized on indium tin oxide (ITO) glass. The effect of electrical stimulation on the proliferation and the length of neurites of PC 12 cells was investigated. The dynamic protein adsorption on PANI and ITO surfaces in a cell culture medium was also compared with and without electrical stimulation. The adsorbed proteins were characterized using SDS-PAGE. A PANI coating on ITO surface was shown with 30-50 nm spherical nanostructure. The number of PC 12 cells was significantly greater on the PANI/ITO surface than on ITO and plate surfaces after cell seeding for 24 and 36 h. This result confirmed that the PANI coating is nontoxic to PC 12 cells. The electrical stimulation for 1, 2, and 4 h significantly enhanced the cell numbers for both PANI and ITO conducting surfaces. Moreover, the application of electrical stimulation also improved the neurite outgrowth of PC 12 cells, and the number of PC 12 cells with longer neurite lengths increased obviously under electrical stimulation for the PANI surface. From the mechanism, the adsorption of DMEM proteins was found to be enhanced by electrical stimulation for both PANI/ITO and ITO surfaces. A new band 2 (around 37 kDa) was observed from the collected adsorbed proteins when PC 12 cells were cultured on these surfaces, and culturing PC 12 cells also seemed to increase the amount of band 1 (around 90 kDa). When immersing PANI/ITO and ITO surfaces in a DMEM medium without a cell culture, the number of band 3 (around 70 kDa) and band 4 (around 45 kDa) proteins decreased compared to that of PC 12 cell cultured surfaces. These results are valuable for the design and improvement of the material performance for neural regeneration.

A conserved WW domain-like motif regulates invariant chain-dependent cell-surface transport of the NKG2D ligand ULBP2.

PubMed

Uhlenbrock, Franziska; van Andel, Esther; Andresen, Lars; Skov, Søren

2015-08-01

Malignant cells expressing NKG2D ligands on their cell surface can be directly sensed and killed by NKG2D-bearing lymphocytes. To ensure this immune recognition, accumulating evidence suggests that NKG2D ligands are trafficed via alternative pathways to the cell surface. We have previously shown that the NKG2D ligand ULBP2 traffics over an invariant chain (Ii)-dependent pathway to the cell surface. This study set out to elucidate how Ii regulates ULBP2 cell-surface transport: We discovered conserved tryptophan (Trp) residues in the primary protein sequence of ULBP1-6 but not in the related MICA/B. Substitution of Trp to alanine resulted in cell-surface inhibition of ULBP2 in different cancer cell lines. Moreover, the mutated ULBP2 constructs were retained and not degraded inside the cell, indicating a crucial role of this conserved Trp-motif in trafficking. Finally, overexpression of Ii increased surface expression of wt ULBP2 while Trp-mutants could not be expressed, proposing that this Trp-motif is required for an Ii-dependent cell-surface transport of ULBP2. Aberrant soluble ULBP2 is immunosuppressive. Thus, targeting a distinct protein module on the ULBP2 sequence could counteract this abnormal expression of ULBP2. Copyright © 2015 Elsevier Ltd. All rights reserved.

Investigation of back surface fields effect on bifacial solar cells

NASA Astrophysics Data System (ADS)

Sepeai, Suhaila; Sulaiman, M. Y.; Sopian, Kamaruzzaman; Zaidi, Saleem H.

2012-11-01

A bifacial solar cell, in contrast with a conventional monofacial solar cell, produces photo-generated current from both front and back sides. Bifacial solar cell is an attractive candidate for enhancing photovoltaic (PV) market competitiveness as well as supporting the current efforts to increase efficiency and lower material costs. This paper reports on the fabrication of bifacial solar cells using phosphorus-oxytrichloride (POCl3) emitter formation on p-type, nanotextured silicon (Si) wafer. Backside surface field was formed through Al-diffusion using conventional screen-printing process. Bifacial solar cells with a structure of n+pp+ with and without back surface field (BSF) were fabricated in which silicon nitride (SiN) anti reflection and passivation films were coated on both sides, followed by screen printing of Argentum (Ag) and Argentum/Aluminum (Ag/Al) on front and back contacts, respectively. Bifacial solar cells without BSF exhibited open circuit voltage (VOC) of 535 mV for front and 480 mV for back surface. With Al-alloyed BSF bifacial solar cells, the VOC improved to 580 mV for the front surface and 560 mV for the back surface. Simulation of bifacial solar cells using PC1D and AFORS software demonstrated good agreement with experimental results. Simulations showed that best bifacial solar cells are achieved through a combination of high lifetime wafer, low recombination back surface field, reduced contact resistance, and superior surface passivation.

Nanotextured titanium surfaces stimulate spreading, migration, and growth of rat mast cells.

PubMed

Marcatti Amarú Maximiano, William; Marino Mazucato, Vivian; Tambasco de Oliveira, Paulo; Célia Jamur, Maria; Oliver, Constance

2017-08-01

Titanium is a biomaterial widely used in dental and orthopedic implants. Since tissue-implant interactions occur at the nanoscale level, nanotextured titanium surfaces may affect cellular activity and modulate the tissue response that occurs at the tissue-implant interface. Therefore, the characterization of diverse cell types in response to titanium surfaces with nanotopography is important for the rational design of implants. Mast cells are multifunctional cells of the immune system that release a range of chemical mediators involved in the inflammatory response that occurs at the tissue-implant interface. Therefore, the aim of this study was to investigate the effects of the nanotopography of titanium surfaces on the physiology of mast cells. The results show that the nanotopography of titanium surfaces promoted the spreading of mast cells, which was accompanied by the reorganization of the cytoskeleton. Also, the nanotopography of titanium surfaces enhanced cell migration and cell growth, but did not alter the number of adherent cells in first hours of culture or affect focal adhesions and mediator release. Thus, the results show that nanotopography of titanium surfaces can affect mast cell physiology, and represents an improved strategy for the rational production of surfaces that stimulate tissue integration with the titanium implants. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2150-2161, 2017. © 2017 Wiley Periodicals, Inc.

Ocular surface reconstruction with a tissue-engineered nasal mucosal epithelial cell sheet for the treatment of severe ocular surface diseases.

PubMed

Kobayashi, Masakazu; Nakamura, Takahiro; Yasuda, Makoto; Hata, Yuiko; Okura, Shoki; Iwamoto, Miyu; Nagata, Maho; Fullwood, Nigel J; Koizumi, Noriko; Hisa, Yasuo; Kinoshita, Shigeru

2015-01-01

Severe ocular surface diseases (OSDs) with severe dry eye can be devastating and are currently some of the most challenging eye disorders to treat. To investigate the feasibility of using an autologous tissue-engineered cultivated nasal mucosal epithelial cell sheet (CNMES) for ocular surface reconstruction, we developed a novel technique for the culture of nasal mucosal epithelial cells expanded ex vivo from biopsy-derived human nasal mucosal tissues. After the protocol, the CNMESs had 4-5 layers of stratified, well-differentiated cells, and we successfully generated cultured epithelial sheets, including numerous goblet cells. Immunohistochemistry confirmed the presence of keratins 3, 4, and 13; mucins 1, 16, and 5AC; cell junction and basement membrane assembly proteins; and stem/progenitor cell marker p75 in the CNMESs. We then transplanted the CNMESs onto the ocular surfaces of rabbits and confirmed the survival of this tissue, including the goblet cells, up to 2 weeks. The present report describes an attempt to overcome the problems of treating severe OSDs with the most severe dry eye by treating them using tissue-engineered CNMESs to supply functional goblet cells and to stabilize and reconstruct the ocular surface. The present study is a first step toward assessing the use of tissue-engineered goblet-cell transplantation of nonocular surface origin for ocular surface reconstruction. ©AlphaMed Press.

Response of MG63 osteoblast-like cells onto polycarbonate membrane surfaces with different micropore sizes.

PubMed

Lee, Sang Jin; Choi, Jin San; Park, Ki Suk; Khang, Gilson; Lee, Young Moo; Lee, Hai Bang

2004-08-01

Response of different types of cells on materials is important for the applications of tissue engineering and regenerative medicine. It is recognized that the behavior of the cell adhesion, proliferation, and differentiation on materials depends largely on surface characteristics such as wettability, chemistry, charge, rigidity, and roughness. In this study, we examined the behavior of MG63 osteoblast-like cells cultured on a polycarbonate (PC) membrane surfaces with different micropore sizes (0.2-8.0 microm in diameter). Cell adhesion and proliferation to the PC membrane surfaces were determined by cell counting and MTT assay. The effect of surface micropore on the MG63 cells was evaluated by cell morphology, protein content, and alkaline phosphatase (ALP) specific activity. It seems that the cell adhesion and proliferation were progressively inhibited as the PC membranes had micropores with increasing size, probably due to surface discontinuities produced by track-etched pores. Increasing micropore size of the PC membrane results in improved protein synthesis and ALP specific activity in isolated cells. There was a statistically significant difference (P<0.05) between different micropore sizes. The MG63 cells also maintained their phenotype under conditions that support a round cell shape. RT-PCR analysis further confirmed the osteogenic phenotype of the MG63 cells onto the PC membranes with different micropore sizes. In results, as micropore size is getting larger, cell number is reduced and cell differentiation and matrix production is increased. This study demonstrated that the surface topography plays an important role for phenotypic expression of the MG63 osteoblast-like cells.

Measurement of In Vivo Three-Dimensional Corneal Cell Density and Size Using Two-Photon Imaging in C57BL/6 Mice.

PubMed

Zhang, Hongmin; He, Siyu; Liu, Susu; Xie, Yanting; Chen, Guoming; Zhang, Junjie; Sun, Shengtao; Liang, David; Wang, Liya

2016-04-01

To measure the cell size and cell density in five layers of the central cornea in the widely used inbred C57BL/6 mouse strain using in vivo three-dimensional (3D) two-photon (2PH) imaging. Corneas were scanned using a 2PH laser scanning fluorescence microscope after staining with plasma membrane stain and Hoechst 33342. Good quality 3D images were selected for the cell density and cell size analysis. Cell density was determined by counting the cell nuclei in a predefined cube of 3D images. Cell size measurements, including cell surface area, cell volume, nuclear surface area and nuclear volume, were automatically quantified using the Imaris software. The cell and nuclear surface-area-to-volume ratio (S:V ratio) and the cell nuclear-cytoplasmic ratio (N:C ratio) were calculated. The highest cell density was observed in the basal epithelium and the lowest in the posterior stroma. The highest cell surface area was found in the anterior stroma, and the highest cell volume was observed in the superficial epithelium. The lowest cell surface area and cell volume were both found in the basal epithelium. The highest S:V ratio was observed in the basal epithelium and the lowest in the superficial epithelium. The highest cell nuclear surface area and volume were both observed in the superficial epithelium and the lowest in the basal epithelium. The highest cell nuclear S:V ratio was observed in the basal epithelium and the lowest in the superficial epithelium. The highest N:C ratio was found in the basal epithelial cells and the lowest in the posterior keratocytes. We are the first to quantify the cell density and size parameters, including cell surface area and volume, cell nuclear surface area and volume, and the S:V ratio, in the five layers of the central cornea. These data provide important cell morphology features for the study of corneal physiology, pathology and disease in mice, particularly in C57BL/6 mice.

Response of cells on surface-induced nanopatterns: fibroblasts and mesenchymal progenitor cells.

PubMed

Khor, Hwei Ling; Kuan, Yujun; Kukula, Hildegard; Tamada, Kaoru; Knoll, Wolfgang; Moeller, Martin; Hutmacher, Dietmar W

2007-05-01

Ultrathin films of a poly(styrene)-block-poly(2-vinylpyrindine) diblock copolymer (PS-b-P2VP) and poly(styrene)-block-poly(4-vinylpyrindine) diblock copolymer (PS-b-P4VP) were used to form surface-induced nanopattern (SINPAT) on mica. Surface interaction controlled microphase separation led to the formation of chemically heterogeneous surface nanopatterns on dry ultrathin films. Two distinct nanopatterned surfaces, namely, wormlike and dotlike patterns, were used to investigate the influence of topography in the nanometer range on cell adhesion, proliferation, and migration. Atomic force microscopy was used to confirm that SINPAT was stable under cell culture conditions. Fibroblasts and mesenchymal progenitor cells were cultured on the nanopatterned surfaces. Phase contrast and confocal laser microscopy showed that fibroblasts and mesenchymal progenitor cells preferred the densely spaced wormlike patterns. Atomic force microscopy showed that the cells remodelled the extracellular matrix differently as they migrate over the two distinctly different nanopatterns.

Solare Cell Roof Tile And Method Of Forming Same

DOEpatents

Hanoka, Jack I.; Real, Markus

1999-11-16

A solar cell roof tile includes a front support layer, a transparent encapsulant layer, a plurality of interconnected solar cells and a backskin layer. The front support layer is formed of light transmitting material and has first and second surfaces. The transparent encapsulant layer is disposed adjacent the second surface of the front support layer. The interconnected solar cells has a first surface disposed adjacent the transparent encapsulant layer. The backskin layer has a first surface disposed adjacent a second surface of the interconnected solar cells, wherein a portion of the backskin layer wraps around and contacts the first surface of the front support layer to form the border region. A portion of the border region has an extended width. The solar cell roof tile may have stand-offs disposed on the extended width border region for providing vertical spacing with respect to an adjacent solar cell roof tile.

Stripe-patterned thermo-responsive cell culture dish for cell separation without cell labeling.

PubMed

Kumashiro, Yoshikazu; Ishihara, Jun; Umemoto, Terumasa; Itoga, Kazuyoshi; Kobayashi, Jun; Shimizu, Tatsuya; Yamato, Masayuki; Okano, Teruo

2015-02-11

A stripe-patterned thermo-responsive surface is prepared to enable cell separation without labeling. The thermo-responsive surface containing a 3 μm striped pattern exhibits various cell adhesion and detachment properties. A mixture of three cell types is separated on the patterned surface based on their distinct cell-adhesion properties, and the composition of the cells is analyzed by flow cytometry. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low proliferation and high apoptosis of osteoblastic cells on hydrophobic surface are associated with defective Ras signaling

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

Chang, Eun-Ju; Kim, Hong-Hee; Huh, Jung-Eun

2005-02-01

The hydrophobic (HPB) nature of most polymeric biomaterials has been a major obstacle in using those materials in vivo due to low compatibility with cells. However, there is little knowledge of the molecular detail to explain how surface hydrophobicity affects cell responses. In this study, we compared the proliferation and apoptosis of human osteoblastic MG63 cells adhered to hydrophilic (HPL) and hydrophobic surfaces. On the hydrophobic surface, less formation of focal contacts and actin stress fibers, a delay in cell cycle progression, and an increase in apoptosis were observed. By using fibroblast growth factor 1 (FGF1) as a model growthmore » factor, we also investigated intracellular signaling pathways on hydrophilic and hydrophobic surfaces. The activation of Ras, Akt, and ERK by FGF1 was impaired in MG63 cells on the hydrophobic surface. The overexpression of constitutively active form of Ras and Akt rescued those cells from apoptosis and recovered cell cycle progression. Furthermore, their overexpression also restored the actin cytoskeletal organization on the hydrophobic surface. Finally, the proliferative, antiapoptotic, and cytoskeletal effects of constitutively active Ras in MG63 cells on the hydrophobic surface were blocked by wortmannin and PD98059 that inhibit Akt and ERK activation, respectively. Therefore, our results suggest that the activation of Ras and its downstream molecules Akt and ERK to an appropriate level is one of crucial elements in the determination of osteoblast cell responses. The Ras pathway may represent a cell biological target that should be considered for successful surface modification of biomaterials to induce adequate cell responses in the bone tissue.« less

Expression Analysis of the Transmembrane Mucin MUC20 in Human Corneal and Conjunctival Epithelia

PubMed Central

Woodward, Ashley M.; Argüeso, Pablo

2014-01-01

Purpose. Cell surface mucins are a group of highly O-glycosylated transmembrane glycoproteins responsible for the protection of epithelial cells on mucosal surfaces. The aim of this study was to investigate the localization and regulation of mucin 20 (MUC20) at the ocular surface. Methods. Localization of MUC20 in human corneal and conjunctival epithelia was evaluated by immunofluorescence microscopy. Immortalized corneal (HCLE) and conjunctival (HCjE) cell lines were grown at different stages of differentiation and subjected to quantitative PCR and Western blot analyses. Cell surface proteins on apical cell membranes were biotinylated and isolated by neutravidin chromatography. Results. The MUC20 was detected throughout the entire human ocular surface epithelia, predominantly in cell membranes within intermediate cell layers. In conjunctiva, MUC20 also was observed in the cytoplasm of apical cells within the stratified squamous epithelium, but not in goblet cells. Quantitative PCR and immunoblotting demonstrated expression of MUC20 in HCLE and HCjE cells. Induction of differentiation with serum-containing medium resulted in upregulation of MUC20 mRNA and protein. Biotin labeling of the surface of stratified cultures revealed low levels of MUC20 protein on apical glycocalyces. Further, MUC20 was not detected in the cell culture media or in human tears, suggesting that the extracellular domain of MUC20 is not released from the ocular surface as described previously for other cell surface mucins. Conclusions. Our results indicate that MUC20 is a novel transmembrane mucin expressed by the human corneal and conjunctival epithelia, and suggest that differential expression of MUC20 during differentiation has a role in maintaining ocular surface homeostasis. PMID:25168902

Nanotopography Promotes Pancreatic Differentiation of Human Embryonic Stem Cells and Induced Pluripotent Stem Cells.

PubMed

Kim, Jong Hyun; Kim, Hyung Woo; Cha, Kyoung Je; Han, Jiyou; Jang, Yu Jin; Kim, Dong Sung; Kim, Jong-Hoon

2016-03-22

Although previous studies suggest that nanotopographical features influence properties and behaviors of stem cells, only a few studies have attempted to derive clinically useful somatic cells from human pluripotent stem cells using nanopatterned surfaces. In the present study, we report that polystyrene nanopore-patterned surfaces significantly promote the pancreatic differentiation of human embryonic and induced pluripotent stem cells. We compared different diameters of nanopores and showed that 200 nm nanopore-patterned surfaces highly upregulated the expression of PDX1, a critical transcription factor for pancreatic development, leading to an approximately 3-fold increase in the percentage of differentiating PDX1(+) pancreatic progenitors compared with control flat surfaces. Furthermore, in the presence of biochemical factors, 200 nm nanopore-patterned surfaces profoundly enhanced the derivation of pancreatic endocrine cells producing insulin, glucagon, or somatostatin. We also demonstrate that nanopore-patterned surface-induced upregulation of PDX1 is associated with downregulation of TAZ, suggesting the potential role of TAZ in nanopore-patterned surface-mediated mechanotransduction. Our study suggests that appropriate cytokine treatments combined with nanotopographical stimulation could be a powerful tool for deriving a high purity of desired cells from human pluripotent stem cells.

Development of a cell culture surface conversion technique using alginate thin film for evaluating effect upon cellular differentiation

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

Nakashima, Y., E-mail: yuta-n@mech.kumamoto-u.ac.jp; Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611; Tsusu, K.

2014-06-15

Here, we sought to develop a cell culture surface conversion technique that would not damage living cells. An alginate thin film, formed on a glass plate by spin coating of sodium alginate solution and dipping into calcium chloride solution, was used to inhibit adhesion of cells. The film could be removed by ethylenediaminetetraacetate (EDTA) at any time during cell culture, permitting observation of cellular responses to conversion of the culture surface in real time. Additionally, we demonstrated the validity of the alginate thin film coating method and the performance of the film. The thickness of the alginate thin film wasmore » controlled by varying the rotation speed during spin coating. Moreover, the alginate thin film completely inhibited the adhesion of cultured cells to the culture surface, irrespective of the thickness of the film. When the alginate thin film was removed from the culture surface by EDTA, the cultured cells adhered to the culture surface, and their morphology changed. Finally, we achieved effective differentiation of C2C12 myoblasts into myotube cells by cell culture on the convertible culture surface, demonstrating the utility of our novel technique.« less

Nanowell-Trapped Charged Ligand-Bearing Nanoparticle Surfaces – A Novel Method of Enhancing Flow-Resistant Cell Adhesion

PubMed Central

Tran, Phat L.; Gamboa, Jessica R.; McCracken, Katherine E.; Riley, Mark R.

2014-01-01

Assuring cell adhesion to an underlying biomaterial surface is vital in implant device design and tissue engineering, particularly under circumstances where cells are subjected to potential detachment from overriding fluid flow. Cell-substrate adhesion is a highly regulated process involving the interplay of mechanical properties, surface topographic features, electrostatic charge, and biochemical mechanisms. At the nanoscale level the physical properties of the underlying substrate are of particular importance in cell adhesion. Conventionally, natural, pro-adhesive, and often thrombogenic, protein biomaterials are frequently utilized to facilitate adhesion. In the present study nanofabrication techniques are utilized to enhance the biological functionality of a synthetic polymer surface, polymethymethacrylate, with respect to cell adhesion. Specifically we examine the effect on cell adhesion of combining: 1. optimized surface texturing, 2. electrostatic charge and 3. cell adhesive ligands, uniquely assembled on the substrata surface, as an ensemble of nanoparticles trapped in nanowells. Our results reveal that the ensemble strategy leads to enhanced, more than simply additive, endothelial cell adhesion under both static and flow conditions. This strategy may be of particular utility for enhancing flow-resistant endothelialization of blood-contacting surfaces of cardiovascular devices subjected to flow-mediated shear. PMID:23225491

Effects of Different Cell-Detaching Methods on the Viability and Cell Surface Antigen Expression of Synovial Mesenchymal Stem Cells.

PubMed

Tsuji, Kunikazu; Ojima, Miyoko; Otabe, Koji; Horie, Masafumi; Koga, Hideyuki; Sekiya, Ichiro; Muneta, Takeshi

2017-06-09

Flow cytometric analysis of cell surface antigens is a powerful tool for the isolation and characterization of stem cells residing in adult tissues. In contrast to the collection of hematopoietic stem cells, the process of enzymatic digestion is usually necessary to prepare mesenchymal stem cells (MSCs) suspensions, which can influence the expression of cell surface markers. In this study, we examined the effects of various cell-detaching reagents and digestion times on the expression of stem cell-related surface antigens and MSC functions. Human MSCs were detached from dishes using four different reagents: trypsin, TrypLE, collagenase, and a nonenzymatic cell dissociation reagent (C5789; Sigma-Aldrich). Following dissociation reagent incubations ranging from 5 to 120 min, cell surface markers were analyzed by flow cytometry. Trypsin and TrypLE quickly dissociated the cells within 5 min, while collagenase and C5789 required 60 min to obtain maximum cell yields. C5789 significantly decreased cell viability at 120 min. Trypsin treatment significantly reduced CD44+, CD55+, CD73+, CD105+, CD140a+, CD140b+, and CD201+ cell numbers within 30 min. Collagenase treatment reduced CD140a expression by 30 min. In contrast, TrypLE treatment did not affect the expression of any cell surface antigens tested by 30 min. Despite the significant loss of surface antigen expression after 60 min of treatment with trypsin, adverse effects of enzymatic digestion on multipotency of MSCs were limited. Overall, our data indicated that TrypLE is advantageous over other cell dissociation reagents tested for the rapid preparation of viable MSC suspensions.

The anticancer activity of lytic peptides is inhibited by heparan sulfate on the surface of the tumor cells

PubMed Central

2009-01-01

Background Cationic antimicrobial peptides (CAPs) with antitumor activity constitute a promising group of novel anticancer agents. These peptides induce lysis of cancer cells through interactions with the plasma membrane. It is not known which cancer cell membrane components influence their susceptibility to CAPs. We have previously shown that CAPs interact with the two glycosaminoglycans (GAGs), heparan sulfate (HS) and chondroitin sulfate (CS), which are present on the surface of most cells. The purpose of this study was to investigate the role of the two GAGs in the cytotoxic activity of CAPs. Methods Various cell lines, expressing different levels of cell surface GAGs, were exposed to bovine lactoferricin (LfcinB) and the designer peptide, KW5. The cytotoxic effect of the peptides was investigated by use of the colorimetric MTT viability assay. The cytotoxic effect on wild type CHO cells, expressing normal amounts of GAGs on the cell surface, and the mutant pgsA-745, that has no expression of GAGs on the cell surface, was also investigated. Results We show that cells not expressing HS were more susceptible to CAPs than cells expressing HS at the cell surface. Further, exogenously added heparin inhibited the cytotoxic effect of the peptides. Chondroitin sulfate had no effect on the cytotoxic activity of KW5 and only minor effects on LfcinB cytotoxicity. Conclusion Our results show for the first time that negatively charged molecules at the surface of cancer cells inhibit the cytotoxic activity of CAPs. Our results indicate that HS at the surface of cancer cells sequesters CAPs away from the phospholipid bilayer and thereby impede their ability to induce cytolysis. PMID:19527490

Citrobacter amalonaticus Phytase on the Cell Surface of Pichia pastoris Exhibits High pH Stability as a Promising Potential Feed Supplement

PubMed Central

Li, Cheng; Lin, Ying; Huang, Yuanyuan; Liu, Xiaoxiao; Liang, Shuli

2014-01-01

Phytase expressed and anchored on the cell surface of Pichia pastoris avoids the expensive and time-consuming steps of protein purification and separation. Furthermore, yeast cells with anchored phytase can be used as a whole-cell biocatalyst. In this study, the phytase gene of Citrobacter amalonaticus was fused with the Pichia pastoris glycosylphosphatidylinositol (GPI)-anchored glycoprotein homologue GCW61. Phytase exposed on the cell surface exhibits a high activity of 6413.5 U/g, with an optimal temperature of 60°C. In contrast to secreted phytase, which has an optimal pH of 5.0, phytase presented on the cell surface is characterized by an optimal pH of 3.0. Moreover, our data demonstrate that phytase anchored on the cell surface exhibits higher pH stability than its secreted counterpart. Interestingly, our in vitro digestion experiments demonstrate that phytase attached to the cell surface is a more efficient enzyme than secreted phytase. PMID:25490768

Citrobacter amalonaticus phytase on the cell surface of Pichia pastoris exhibits high pH stability as a promising potential feed supplement.

PubMed

Li, Cheng; Lin, Ying; Huang, Yuanyuan; Liu, Xiaoxiao; Liang, Shuli

2014-01-01

Phytase expressed and anchored on the cell surface of Pichia pastoris avoids the expensive and time-consuming steps of protein purification and separation. Furthermore, yeast cells with anchored phytase can be used as a whole-cell biocatalyst. In this study, the phytase gene of Citrobacter amalonaticus was fused with the Pichia pastoris glycosylphosphatidylinositol (GPI)-anchored glycoprotein homologue GCW61. Phytase exposed on the cell surface exhibits a high activity of 6413.5 U/g, with an optimal temperature of 60°C. In contrast to secreted phytase, which has an optimal pH of 5.0, phytase presented on the cell surface is characterized by an optimal pH of 3.0. Moreover, our data demonstrate that phytase anchored on the cell surface exhibits higher pH stability than its secreted counterpart. Interestingly, our in vitro digestion experiments demonstrate that phytase attached to the cell surface is a more efficient enzyme than secreted phytase.

Heterogeneity of chemokine cell-surface receptor expression in triple-negative breast cancer

PubMed Central

Norton, Kerri-Ann; Popel, Aleksander S; Pandey, Niranjan B

2015-01-01

Introduction: Tumor heterogeneity is a well-established concept in cancer research. In this paper, we examine an additional type of tumor cell heterogeneity - tumor cell-surface receptor heterogeneity. Methods: We use flow cytometry to measure the frequency and numbers of cell-surface receptors on triple negative breast cancer cell lines. Results: We find two distinct populations of human triple-negative breast cancer cells MDA-MB-231 when they are grown in culture, one with low surface levels of various chemokine receptors and a second with much higher levels. The population with high surface levels of these receptors is increased in the more metastatic MDA-MB-231-luc-d3h2ln cell line. Conclusion: We hypothesize that this high cell-surface receptor population is involved in metastasis. We find that the receptor high populations can be modulated by tumor conditioned media and IL6 treatment indicating that the tumor microenvironment is important for the maintenance and sizes of these populations. PMID:26101698

Chemical Reactive Anchoring Lipids with Different Performance for Cell Surface Re-engineering Application.

PubMed

Vabbilisetty, Pratima; Boron, Mallorie; Nie, Huan; Ozhegov, Evgeny; Sun, Xue-Long

2018-02-28

Introduction of selectively chemical reactive groups at the cell surface enables site-specific cell surface labeling and modification opportunity, thus facilitating the capability to study the cell surface molecular structure and function and the molecular mechanism it underlies. Further, it offers the opportunity to change or improve a cell's functionality for interest of choice. In this study, two chemical reactive anchor lipids, phosphatidylethanolamine-poly(ethylene glycol)-dibenzocyclooctyne (DSPE-PEG 2000 -DBCO) and cholesterol-PEG-dibenzocyclooctyne (CHOL-PEG 2000 -DBCO) were synthesized and their potential application for cell surface re-engineering via lipid fusion were assessed with RAW 264.7 cells as a model cell. Briefly, RAW 264.7 cells were incubated with anchor lipids under various concentrations and at different incubation times. The successful incorporation of the chemical reactive anchor lipids was confirmed by biotinylation via copper-free click chemistry, followed by streptavidin-fluorescein isothiocyanate binding. In comparison, the cholesterol-based anchor lipid afforded a higher cell membrane incorporation efficiency with less internalization than the phospholipid-based anchor lipid. Low cytotoxicity of both anchor lipids upon incorporation into the RAW 264.7 cells was observed. Further, the cell membrane residence time of the cholesterol-based anchor lipid was evaluated with confocal microscopy. This study suggests the potential cell surface re-engineering applications of the chemical reactive anchor lipids.

Phenotypic Heterogeneity and the Evolution of Bacterial Life Cycles.

PubMed

van Gestel, Jordi; Nowak, Martin A

2016-02-01

Most bacteria live in colonies, where they often express different cell types. The ecological significance of these cell types and their evolutionary origin are often unknown. Here, we study the evolution of cell differentiation in the context of surface colonization. We particularly focus on the evolution of a 'sticky' cell type that is required for surface attachment, but is costly to express. The sticky cells not only facilitate their own attachment, but also that of non-sticky cells. Using individual-based simulations, we show that surface colonization rapidly evolves and in most cases leads to phenotypic heterogeneity, in which sticky and non-sticky cells occur side by side on the surface. In the presence of regulation, cell differentiation leads to a remarkable set of bacterial life cycles, in which cells alternate between living in the liquid and living on the surface. The dominant life stage is formed by the surface-attached colony that shows many complex features: colonies reproduce via fission and by producing migratory propagules; cells inside the colony divide labour; and colonies can produce filaments to facilitate expansion. Overall, our model illustrates how the evolution of an adhesive cell type goes hand in hand with the evolution of complex bacterial life cycles.

Fabrication of Biocompatible Potassium Sodium Niobate Piezoelectric Ceramic as an Electroactive Implant

PubMed Central

Chen, Wei; Yu, Zunxiong; Pang, Jinshan; Yu, Peng; Tan, Guoxin; Ning, Chengyun

2017-01-01

The discovery of piezoelectricity in natural bone has attracted extensive research in emulating biological electricity for various tissue regeneration. Here, we carried out experiments to build biocompatible potassium sodium niobate (KNN) ceramics. Then, influence substrate surface charges on bovine serum albumin (BSA) protein adsorption and cell proliferation on KNN ceramics surfaces was investigated. KNN ceramics with piezoelectric constant of ~93 pC/N and relative density of ~93% were fabricated. The adsorption of protein on the positive surfaces (Ps) and negative surfaces (Ns) of KNN ceramics with piezoelectric constant of ~93 pC/N showed greater protein adsorption capacity than that on non-polarized surfaces (NPs). Biocompatibility of KNN ceramics was verified through cell culturing and live/dead cell staining of MC3T3. The cells experiment showed enhanced cell growth on the positive surfaces (Ps) and negative surfaces (Ns) compared to non-polarized surfaces (NPs). These results revealed that KNN ceramics had great potential to be used to understand the effect of surface potential on cells processes and would benefit future research in designing piezoelectric materials for tissue regeneration. PMID:28772704

Fabrication of Biocompatible Potassium Sodium Niobate Piezoelectric Ceramic as an Electroactive Implant.

PubMed

Chen, Wei; Yu, Zunxiong; Pang, Jinshan; Yu, Peng; Tan, Guoxin; Ning, Chengyun

2017-03-26

The discovery of piezoelectricity in natural bone has attracted extensive research in emulating biological electricity for various tissue regeneration. Here, we carried out experiments to build biocompatible potassium sodium niobate (KNN) ceramics. Then, influence substrate surface charges on bovine serum albumin (BSA) protein adsorption and cell proliferation on KNN ceramics surfaces was investigated. KNN ceramics with piezoelectric constant of ~93 pC/N and relative density of ~93% were fabricated. The adsorption of protein on the positive surfaces (Ps) and negative surfaces (Ns) of KNN ceramics with piezoelectric constant of ~93 pC/N showed greater protein adsorption capacity than that on non-polarized surfaces (NPs). Biocompatibility of KNN ceramics was verified through cell culturing and live/dead cell staining of MC3T3. The cells experiment showed enhanced cell growth on the positive surfaces (Ps) and negative surfaces (Ns) compared to non-polarized surfaces (NPs). These results revealed that KNN ceramics had great potential to be used to understand the effect of surface potential on cells processes and would benefit future research in designing piezoelectric materials for tissue regeneration.

Bone cell-materials interactions and Ni ion release of anodized equiatomic NiTi alloy.

PubMed

Bernard, Sheldon A; Balla, Vamsi Krishna; Davies, Neal M; Bose, Susmita; Bandyopadhyay, Amit

2011-04-01

A laser processed NiTi alloy was anodized for different times in H(2)SO(4) electrolyte with varying pH to create biocompatible surfaces with low Ni ion release as well as bioactive surfaces to enhance biocompatibility and bone cell-material interactions. The anodized surfaces were assessed for their in vitro cell-material interactions using human fetal osteoblast (hFOB) cells for 3, 7 and 11 days, and Ni ion release up to 8 weeks in simulated body fluids. The results were correlated with the surface morphologies of anodized surfaces characterized using field-emission scanning electron microscopy (FESEM). The results show that anodization creates a surface with nano/micro-roughness depending on the anodization conditions. The hydrophilicity of the NiTi surface was found to improve after anodization, as shown by the lower contact angles in cell medium, which dropped from 32° to <5°. The improved wettability of anodized surfaces is further corroborated by their high surface energy, comparable with that of commercially pure Ti. Relatively high surface energies, especially the polar component, and nano/micro surface features of anodized surfaces significantly increased the number of living cells and their adherence and growth on these surfaces. Finally, a significant drop in Ni ion release from 268±11 to 136±15 ppb was observed for NiTi surfaces after anodization. This work indicates that anodization of a NiTi alloy has a positive influence on the surface energy and surface morphology, which in turn improves bone cell-material interactions and reduces Ni ion release in vitro. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effects of Titanium Surface Microtopography and Simvastatin on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells in Estrogen-Deprived Cell Culture.

PubMed

Arpornmaeklong, Premjit; Pripatnanont, Prisana; Chookiatsiri, Chonticha; Tangtrakulwanich, Boonsin

This study aimed to investigate the effects of titanium surface topography and simvastatin on growth and osteogenic differentiation of human bone marrow stromal cells (hBMSCs) in estrogen-deprived (ED) cell culture. Human BMSCs were seeded on cell culture plates, smooth-surface titanium (Ti) disks, and sandblasted with large grits and acid etched (SLA)-surface Ti disks; and subsequently cultured in regular (fetal bovine serum [FBS]), ED, and ED-with 100 nM simvastatin (ED-SIM) culture media for 14 to 21 days. Live/dead cell staining, scanning electron microscope examination, and cell viability assay were performed to determine cell attachment, morphology, and growth. Expression levels of osteoblast-associated genes, Runx2 and bone sialoprotein and levels of alkaline phosphatase (ALP) activity, calcium content, and osteocalcin in culture media were measured to determine osteoblastic differentiation. Expression levels of bone morphogenetic protein-2 (BMP-2) were investigated to examine stimulating effects of simvastatin (n = 4 to 5, mean ± SD). In vitro mineralization was verified by calcein staining. Human BMSCs exhibited different attachment and shapes on smooth and SLA titanium surfaces. Estrogen-deprived cell culture decreased cell attachment and growth, particularly on the SLA titanium surface, but cells were able to grow to reach confluence on day 21 in the ED-osteogenic (OS) culture medium. Promoting effects of the SLA titanium surface in ED-OS were significantly decreased. Simvastatin significantly increased osteogenic differentiation of human BMSCs on the SLA titanium surface in the ED-OS medium, and the promoting effects of simvastatin corresponded with the increasing of BMP-2 gene expression on the SLA titanium surface in ED-OS-SIM culture medium. The ED cell culture model provided a well-defined platform for investigating the effects of hormones and growth factors on cells and titanium surface interaction. Titanium, the SLA surface, and simvastatin synergistically promoted osteoblastic differentiation of hBMSCs in ED condition and might be useful to promote osteointegration in osteoporotic bone.

Role of heme in intracellular trafficking of thyroperoxidase and involvement of H2O2 generated at the apical surface of thyroid cells in autocatalytic covalent heme binding.

PubMed

Fayadat, L; Niccoli-Sire, P; Lanet, J; Franc, J L

1999-04-09

Thyroperoxidase (TPO) is a glycosylated hemoprotein that plays a key role in thyroid hormone synthesis. We previously showed that in CHO cells expressing human TPO (hTPO) only 2% of synthesized hTPO reaches the cell surface. Herein, we investigated the role of heme moiety insertion in the exit of hTPO from the endoplasmic reticulum. Peroxidase activity at the cell surface and cell surface expression of hTPO were decreased by approximately 30 and approximately 80%, respectively, with succinyl acetone, an inhibitor of heme biosynthesis, and were increased by 20% with holotransferrin and aminolevulinic acid, precursors of heme biosynthesis. Results were similar with holotransferrin plus aminolevulinic acid or hemin, but hemin increased cell surface activity more efficiently (+120%) relative to the control. It had been suggested (DePillis, G., Ozaki, S., Kuo, J. M., Maltby, D. A., and Ortiz de Montellano, P. R. (1997) J. Biol. Chem. 272, 8857-8960) that covalent attachment of heme to mammalian peroxidases could be an H2O2-dependent autocatalytic processing. In our study, heme associated intracellularly with hTPO, and we hypothesized that there was insufficient exposure to H2O2 in Chinese hamster ovary cells before hTPO reached the cell surface. After a 10-min incubation, 10 microM H2O2 led to a 65% increase in cell surface activity. In contrast, in thyroid cells, H2O2 was synthesized at the apical cell surface and allowed covalent attachment of heme. Two-day incubation of primocultures of thyroid cells with catalase led to a 30% decrease in TPO activity at the cell surface. In conclusion, we provide compelling evidence for an essential role of 1) heme incorporation in the intracellular trafficking of hTPO and of 2) H2O2 generated at the apical pole of thyroid cells in the autocatalytic covalent heme binding to the TPO molecule.

The Escherichia coli Subtilase Cytotoxin A Subunit Specifically Cleaves Cell-surface GRP78 Protein and Abolishes COOH-terminal-dependent Signaling

PubMed Central

Ray, Rupa; de Ridder, Gustaaf G.; Eu, Jerry P.; Paton, Adrienne W.; Paton, James C.; Pizzo, Salvatore V.

2012-01-01

GRP78, a molecular chaperone with critical endoplasmic reticulum functions, is aberrantly expressed on the surface of cancer cells, including prostate and melanoma. Here it functions as a pro-proliferative and anti-apoptotic signaling receptor via NH2-terminal domain ligation. Auto-antibodies to this domain may appear in cancer patient serum where they are a poor prognostic indicator. Conversely, GRP78 COOH-terminal domain ligation is pro-apoptotic and anti-proliferative. There is no method to disrupt cell-surface GRP78 without compromising the total GRP78 pool, making it difficult to study cell-surface GRP78 function. We studied six cell lines representing three cancer types. One cell line per group expresses high levels of cell-surface GRP78, and the other expresses low levels (human hepatoma: Hep3B and HepG2; human prostate cancer: PC3 and 1-LN; murine melanoma: B16F0 and B16F1). We investigated the effect of Escherichia coli subtilase cytoxin catalytic subunit (SubA) on GRP78. We report that SubA specifically cleaves cell-surface GRP78 on HepG2, 1-LN, and B16F1 cells without affecting intracellular GRP78. B16F0 cells (GRP78low) have lower amounts of cleaved cell-surface GRP78. SubA has no effect on Hep3B and PC3 cells. The predicted 28-kDa GRP78 COOH-terminal fragment is released into the culture medium by SubA treatment, and COOH-terminal domain signal transduction is abrogated, whereas pro-proliferative signaling mediated through NH2-terminal domain ligation is unaffected. These experiments clarify cell-surface GRP78 topology and demonstrate that the COOH-terminal domain is necessary for pro-apoptotic signal transduction occurring upon COOH-terminal antibody ligation. SubA is a powerful tool to specifically probe the functions of cell-surface GRP78. PMID:22851173

The Escherichia coli subtilase cytotoxin A subunit specifically cleaves cell-surface GRP78 protein and abolishes COOH-terminal-dependent signaling.

PubMed

Ray, Rupa; de Ridder, Gustaaf G; Eu, Jerry P; Paton, Adrienne W; Paton, James C; Pizzo, Salvatore V

2012-09-21

GRP78, a molecular chaperone with critical endoplasmic reticulum functions, is aberrantly expressed on the surface of cancer cells, including prostate and melanoma. Here it functions as a pro-proliferative and anti-apoptotic signaling receptor via NH(2)-terminal domain ligation. Auto-antibodies to this domain may appear in cancer patient serum where they are a poor prognostic indicator. Conversely, GRP78 COOH-terminal domain ligation is pro-apoptotic and anti-proliferative. There is no method to disrupt cell-surface GRP78 without compromising the total GRP78 pool, making it difficult to study cell-surface GRP78 function. We studied six cell lines representing three cancer types. One cell line per group expresses high levels of cell-surface GRP78, and the other expresses low levels (human hepatoma: Hep3B and HepG2; human prostate cancer: PC3 and 1-LN; murine melanoma: B16F0 and B16F1). We investigated the effect of Escherichia coli subtilase cytoxin catalytic subunit (SubA) on GRP78. We report that SubA specifically cleaves cell-surface GRP78 on HepG2, 1-LN, and B16F1 cells without affecting intracellular GRP78. B16F0 cells (GRP78(low)) have lower amounts of cleaved cell-surface GRP78. SubA has no effect on Hep3B and PC3 cells. The predicted 28-kDa GRP78 COOH-terminal fragment is released into the culture medium by SubA treatment, and COOH-terminal domain signal transduction is abrogated, whereas pro-proliferative signaling mediated through NH(2)-terminal domain ligation is unaffected. These experiments clarify cell-surface GRP78 topology and demonstrate that the COOH-terminal domain is necessary for pro-apoptotic signal transduction occurring upon COOH-terminal antibody ligation. SubA is a powerful tool to specifically probe the functions of cell-surface GRP78.

Biosynthetic maturation of an ascites tumor cell surface sialomucin. Evidence for O-glycosylation of cell surface glycoprotein by the addition of new oligosaccharides during recycling.

PubMed

Hull, S R; Sugarman, E D; Spielman, J; Carraway, K L

1991-07-25

Previous biosynthetic studies of the ascites 13762 rat mammary adenocarcinoma cell surface sialomucin ASGP-1 (ascites sialoglycoprotein-1) showed that it is synthesized initially as a poorly glycosylated immature form, which is converted to a larger premature form (t1/2 30 min) and more slowly to the mature glycoprotein (t1/2 greater than 4 h). In the present study O-glycosylation of ASGP-1 polypeptide is shown to occur in two phases: an early phase complete in less than 30 min, which corresponds to the synthesis of the premature form, and a later phase that continues for hours and corresponds to the synthesis of the mature form. Pulse-chase labeling studies indicate that 95% of the ASGP-1 has moved to the cell surface in 2 h. Since transit to the cell surface is faster than the slow phase of addition of new oligosaccharides, some new oligosaccharides must be added after ASGP-1 has reached the cell surface. Initiation of new oligosaccharides on cell surface ASGP-1 was demonstrated directly using a biotinylation procedure to identify cell surface molecules. Glucosamine labeling of biotinylated ASGP-1 was shown to occur on galactosamine residues, which are linked to the polypeptide, establishing the addition of new oligosaccharides to the cell surface molecules. Finally, resialylation studies indicate that ASGP-1 rapidly recycles through a sialylating compartment. From these results we propose that ASGP-1 reaches the cell surface in an incompletely glycosylated state and that additional oligosaccharides are added to the glycoprotein in a second process involving recycling.

Cellular and Molecular Level Responses After Radiofrequency Radiation Exposure, Alone or in Combination with X-rays or Chemicals

DTIC Science & Technology

1992-07-27

cell surface marker CD22 , which plays a role in early B-cell activation, is present within the cytoplasm of all B- cells, but expressed only on the...surface of a subpopulation of those cells. CD22 is an activation receptor associated with cell proliferation of small resting B-cells, and acts as an...adhesion molecule mediating the binding of B-cells to other hematopoietic cells (Stamenkovic & Seed, 1990). The CD22 surface glycoprotein is the putative

Characterization of the Cell Surface Properties of Drinking Water Pathogens by Microbial Adhesion to Hydrocarbon and Electrophoretic Mobility Measurements

EPA Science Inventory

The surface characteristics of microbial cells directly influence their mobility and behavior within aqueous environments. The cell surface hydrophobicity (CSH) and electrophoretic mobility (EPM) of microbial cells impact a number of interactions and processes including aggregati...

Impact of cell shape in hierarchically structured plant surfaces on the attachment of male Colorado potato beetles (Leptinotarsa decemlineata)

PubMed Central

Seidel, Robin; Bohn, Holger Florian; Speck, Thomas

2012-01-01

Summary Plant surfaces showing hierarchical structuring are frequently found in plant organs such as leaves, petals, fruits and stems. In our study we focus on the level of cell shape and on the level of superimposed microstructuring, leading to hierarchical surfaces if both levels are present. While it has been shown that epicuticular wax crystals and cuticular folds strongly reduce insect attachment, and that smooth papillate epidermal cells in petals improve the grip of pollinators, the impact of hierarchical surface structuring of plant surfaces possessing convex or papillate cells on insect attachment remains unclear. We performed traction experiments with male Colorado potato beetles on nine different plant surfaces with different structures. The selected plant surfaces showed epidermal cells with either tabular, convex or papillate cell shape, covered either with flat films of wax, epicuticular wax crystals or with cuticular folds. On surfaces possessing either superimposed wax crystals or cuticular folds we found traction forces to be almost one order of magnitude lower than on surfaces covered only with flat films of wax. Independent of superimposed microstructures we found that convex and papillate epidermal cell shapes slightly enhance the attachment ability of the beetles. Thus, in plant surfaces, cell shape and superimposed microstructuring yield contrary effects on the attachment of the Colorado potato beetle, with convex or papillate cells enhancing attachment and both wax crystals or cuticular folds reducing attachment. However, the overall magnitude of traction force mainly depends on the presence or absence of superimposed microstructuring. PMID:22428097

Exopolysaccharide-Independent Social Motility of Myxococcus xanthus

PubMed Central

Hu, Wei; Hossain, Muhaiminu; Lux, Renate; Wang, Jing; Yang, Zhe; Li, Yuezhong; Shi, Wenyuan

2011-01-01

Social motility (S motility), the coordinated movement of large cell groups on agar surfaces, of Myxococcus xanthus requires type IV pili (TFP) and exopolysaccharides (EPS). Previous models proposed that this behavior, which only occurred within cell groups, requires cycles of TFP extension and retraction triggered by the close interaction of TFP with EPS. However, the curious observation that M. xanthus can perform TFP-dependent motility at a single-cell level when placed onto polystyrene surfaces in a highly viscous medium containing 1% methylcellulose indicated that “S motility” is not limited to group movements. In an apparent further challenge of the previous findings for S motility, mutants defective in EPS production were found to perform TFP-dependent motility on polystyrene surface in methylcellulose-containing medium. By exploring the interactions between pilin and surface materials, we found that the binding of TFP onto polystyrene surfaces eliminated the requirement for EPS in EPS- cells and thus enabled TFP-dependent motility on a single cell level. However, the presence of a general anchoring surface in a viscous environment could not substitute for the role of cell surface EPS in group movement. Furthermore, EPS was found to serve as a self-produced anchoring substrate that can be shed onto surfaces to enable cells to conduct TFP-dependent motility regardless of surface properties. These results suggested that in certain environments, such as in methylcellulose solution, the cells could bypass the need for EPS to anchor their TPF and conduct single-cell S motility to promote exploratory movement of colonies over new specific surfaces. PMID:21245931

Cell behavior on surface modified polydimethylsiloxane (PDMS).

PubMed

Stanton, Morgan M; Rankenberg, Johanna M; Park, Byung-Wook; McGimpsey, W Grant; Malcuit, Christopher; Lambert, Christopher R

2014-07-01

Designing complex tissue culture systems requires cell alignment and directed extracellular matrix (ECM) and gene expression. Here, a micro-rough, polydimethylsiloxane (PDMS) surface, that also integrates a micro-pattern of 50 µm wide lines of fibronectin (FN) separated by 60 µm wide lines of bovine serum albumin (BSA), is developed. Human fibroblasts cultured on the rough, patterned substrate have aligned growth and a significant change in morphology when compared to cells on a flat, patterned surface. The rough PDMS topography significantly decreases cell area and induces the upregulation of several ECM related genes by two-fold when compared to cells cultured on flat PDMS. This study describes a simple surface engineering procedure for creating surface architecture for scaffolds to design and control the cell-surface interface. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stem cell behavior on tailored porous oxide surface coatings.

PubMed

Lavenus, Sandrine; Poxson, David J; Ogievetsky, Nika; Dordick, Jonathan S; Siegel, Richard W

2015-07-01

Nanoscale surface topographies are known to have a profound influence on cell behavior, including cell guidance, migration, morphology, proliferation, and differentiation. In this study, we have observed the behavior of human mesenchymal stem cells cultured on a range of tailored porous SiO2 and TiO2 nanostructured surface coatings fabricated via glancing angle electron-beam deposition. By controlling the physical vapor deposition angle during fabrication, we could control systematically the deposited coating porosity, along with associated topographic features. Immunocytochemistry and image analysis quantitatively revealed the number of adherent cells, as well as their basic cellular morphology, on these surfaces. Signaling pathway studies showed that even with subtle changes in nanoscale surface structures, the behavior of mesenchymal stem cells was strongly influenced by the precise surface structures of these porous coatings. Copyright © 2015 Elsevier Ltd. All rights reserved.

New Monoclonal Antibodies to Defined Cell Surface Proteins on Human Pluripotent Stem Cells.

PubMed

O'Brien, Carmel M; Chy, Hun S; Zhou, Qi; Blumenfeld, Shiri; Lambshead, Jack W; Liu, Xiaodong; Kie, Joshua; Capaldo, Bianca D; Chung, Tung-Liang; Adams, Timothy E; Phan, Tram; Bentley, John D; McKinstry, William J; Oliva, Karen; McMurrick, Paul J; Wang, Yu-Chieh; Rossello, Fernando J; Lindeman, Geoffrey J; Chen, Di; Jarde, Thierry; Clark, Amander T; Abud, Helen E; Visvader, Jane E; Nefzger, Christian M; Polo, Jose M; Loring, Jeanne F; Laslett, Andrew L

2017-03-01

The study and application of human pluripotent stem cells (hPSCs) will be enhanced by the availability of well-characterized monoclonal antibodies (mAbs) detecting cell-surface epitopes. Here, we report generation of seven new mAbs that detect cell surface proteins present on live and fixed human ES cells (hESCs) and human iPS cells (hiPSCs), confirming our previous prediction that these proteins were present on the cell surface of hPSCs. The mAbs all show a high correlation with POU5F1 (OCT4) expression and other hPSC surface markers (TRA-160 and SSEA-4) in hPSC cultures and detect rare OCT4 positive cells in differentiated cell cultures. These mAbs are immunoreactive to cell surface protein epitopes on both primed and naive state hPSCs, providing useful research tools to investigate the cellular mechanisms underlying human pluripotency and states of cellular reprogramming. In addition, we report that subsets of the seven new mAbs are also immunoreactive to human bone marrow-derived mesenchymal stem cells (MSCs), normal human breast subsets and both normal and tumorigenic colorectal cell populations. The mAbs reported here should accelerate the investigation of the nature of pluripotency, and enable development of robust cell separation and tracing technologies to enrich or deplete for hPSCs and other human stem and somatic cell types. Stem Cells 2017;35:626-640. © 2016 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Infection of Polarized MDCK Cells with Herpes Simplex Virus 1: Two Asymmetrically Distributed Cell Receptors Interact with Different Viral Proteins

NASA Astrophysics Data System (ADS)

Sears, Amy E.; McGwire, Bradford S.; Roizman, Bernard

1991-06-01

Herpes simplex virus 1 attaches to at least two cell surface receptors. In polarized epithelial (Madin-Darby canine kidney; MDCK) cells one receptor is located in the apical surface and attachment to the cells requires the presence of glycoprotein C in the virus. The second receptor is located in the basal surface and does not require the presence of glycoprotein C. Exposure of MDCK cells at either the apical or basal surface to wild-type virus yields plaques and viral products whereas infection by a glycoprotein C-negative mutant yields identical results only after exposure of MDCK cells to virus at the basal surface. Multiple receptors for viral entry into cells expand the host range of the virus. The observation that glycoprotein C-negative mutants are infectious in many nonpolarized cell lines suggests that cells in culture may express more than one receptor and explains why genes that specify the viral proteins that recognize redundant receptors, like glycoprotein C, are expendable.

The interaction between LYVE-1 with hyaluronan on the cell surface may play a role in the diversity of adhesion to cancer cells.

PubMed

Du, Yan; Liu, Hua; He, Yiqing; Liu, Yiwen; Yang, Cuixia; Zhou, Muqing; Wang, Wenjuan; Cui, Lian; Hu, Jiajie; Gao, Feng

2013-01-01

Hyaluronan (HA), a simple disaccharide unit, can polymerize and is considered a primary component of the extracellular matrix, which has a wide range of biological functions. In recent years, HA was found on the surface of tumor cells. According to previous reports, differing HA content on the cell surface of tumor cells is closely related to lymph node metastases, but the mechanisms mediating this process remained unclear. This research intended to study the surface content of HA on tumor cells and analyze cell adhesive changes caused by the interaction between HA and its lymphatic endothelial receptor (LYVE-1). We screened and observed high HA content on HS-578T breast cells and low HA content on MCF-7 breast cells through particle exclusion, immunofluorescence and flow cytometry experiments. The expression of LYVE-1, the lymph-vessel specific HA receptor, was consistent with our previous report and enhanced the adhesion of HA(high)-HS-578T cells to COS-7(LYVE-1(+)) through HA in cell static adhesion and dynamic parallel plate flow chamber experiments. MCF-7 breast cells contain little HA on the surface; however, our results showed little adhesion difference between MCF-7 cells and COS-7(LYVE-1(+)) and COS-7(LYVE-1(-)) cells. Similar results were observed concerning the adhesion of HS-578T cells or MCF-7 cells to SVEC4-10 cells. Furthermore, we observed for the first time that the cell surface HA content of high transfer tumor cells was rich, and we visualized the cross-linking of HA cable structures, which may activate LYVE-1 on lymphatic endothelial cells, promoting tumor adhesion. In summary, high-low cell surface HA content of tumor cells through the interaction with LYVE-1 leads to adhesion differences.

Effect of Atmospheric Plasma Treatment to Titanium Surface on Initial Osteoblast-Like Cell Spreading. .

PubMed

Kim, In-Hye; Son, Jun-Sik; Kwon, Tae-Yub; Kim, Kyo-Han

2015-01-01

Plasma treatments are becoming a popular method for modifying the characteristics of a range of substrate surfaces. Atmospheric pressure plasma is cost-efficient, safe and simple compared to high-pressure plasma. This study examined the effects of atmospheric pressure plasma to a titanium (Ti) surface on osteoblast-like cell (osteoblast) spreading and cellular networks. The characteristics of the Ti surface before and after the atmospheric plasma treatment were analyzed by X-ray photoemission spectroscopy (XPS), scanning electron microscopy (SEM), contact angle measurements, and an optical 3D profiling system. The morphology of osteoblasts attached to the Ti surfaces was observed by SEM and confocal laser scanning microscopy. The atmospheric pressure plasma made the Ti surfaces more hydrophilic. The osteoblasts that adhered to the untreated surface were round and spherical, whereas the cells covered a larger surface area on the plasma-treated surface. The plasma-treated Ti surface showed enhanced cell spreading and migration with more developed cellular networks. In conclusion, an atmospheric plasma treatment is a potential surface modifying method that can enhance the initial the cell affinity at the early stages in vitro.

Biocompatibility enhancement of rare earth magnesium alloy by laser surface processing

NASA Astrophysics Data System (ADS)

Nie, Shilin; Wang, Yuqing; Liu, Haifeng; Guan, Yingchun

2018-01-01

Although magnesium and magnesium alloys are considered biocompatible and biodegradable, insufficient biocompatibility in body fluid environment is still the major drawback of magnesium alloys for their successful applications as biodegradable orthopaedic implants. In this work, magnesium alloy surface with both enhanced corrosion resistance and better cell adhesion property was directly fabricated by laser surface processing. Laser surface melting was used to improve corrosion resistance of Mg-6Gd-0.6Ca alloy. After laser surface melting, laser surface texturing was utilized on melted surface for better cell adhesion property. The corrosion resistance of laser-treated and as-received samples were evaluated using electrochemical technique. The effect of laser surface treatment on phase and microstructure evolution was evaluated using scanning electron microscopy, optical microscopy and X-ray diffraction. This work investigated the effect of laser treatment on cell distribution across the surface of magnesium alloy substrates. Osteoblast was cultured on the laser-treated surface and as-received surface. Cell morphology was observed with a scanning electron microscopy, and cell viability was evaluated by optical density measurement.

Origin of tumor-promoter released fibronectin in fibroblasts

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

Burrous, B.A.; Wolf, G.

1986-05-01

Previous work from the laboratory showed that the chemical tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulated release of the cell surface glycoprotein, fibronectin (FN) from human lung fibroblasts (HLF), leading to depletion of cell surface FN, while FN synthesis is not altered by TPA. To further investigate the mechanism(s) by which TPA stimulates FN release, two types of experiments were performed. In the first, HLF were pulsed with /sup 35/S-methionine-labeled medium with or without TPA. In the second, cell-surface proteins were labeled by iodination (/sup 125/I) and then incubated in unlabeled medium with or without TPA. In both cases, the fate ofmore » labeled FN was followed over 12 hr. The /sup 35/S-meth-labeled HLF showed a rapid loss of labeled FN, first into a small, highly-labeled pool of cell surface FN (1 hr), later into the medium (4 hr or longer). Specific activities showed that this small pool in the cell surface turned over rapidly. TPA treatment resulted in more rapid movement of /sup 35/S-meth pulse-labeled FN to the cell surface and into the medium than in control cells. TPA thus affected the fate of intracellular FN. TPA treatment of HLF also resulted in more rapid removal of /sup 125/I-cell surface-labeled FN into the medium than in control cells. Thus, TPA affects the fate of preexisting cell surface FN in HLF. From these results, they hypothesize that TPA has two separate effects: it stimulates depletion of preexisting intracellular FN during the first hr of treatment, and it stimulates release of preexisting cell surface FN over all treatment times.« less

Membrane dynamics of dividing cells imaged by lattice light-sheet microscopy

PubMed Central

Aguet, François; Upadhyayula, Srigokul; Gaudin, Raphaël; Chou, Yi-ying; Cocucci, Emanuele; He, Kangmin; Chen, Bi-Chang; Mosaliganti, Kishore; Pasham, Mithun; Skillern, Wesley; Legant, Wesley R.; Liu, Tsung-Li; Findlay, Greg; Marino, Eric; Danuser, Gaudenz; Megason, Sean; Betzig, Eric; Kirchhausen, Tom

2016-01-01

Membrane remodeling is an essential part of transferring components to and from the cell surface and membrane-bound organelles and for changes in cell shape, which are particularly critical during cell division. Earlier analyses, based on classical optical live-cell imaging and mostly restricted by technical necessity to the attached bottom surface, showed persistent formation of endocytic clathrin pits and vesicles during mitosis. Taking advantage of the resolution, speed, and noninvasive illumination of the newly developed lattice light-sheet fluorescence microscope, we reexamined their assembly dynamics over the entire cell surface and found that clathrin pits form at a lower rate during late mitosis. Full-cell imaging measurements of cell surface area and volume throughout the cell cycle of single cells in culture and in zebrafish embryos showed that the total surface increased rapidly during the transition from telophase to cytokinesis, whereas cell volume increased slightly in metaphase and was relatively constant during cytokinesis. These applications demonstrate the advantage of lattice light-sheet microscopy and enable a new standard for imaging membrane dynamics in single cells and multicellular assemblies. PMID:27535432

Cell surface characteristics enable encrustation-free survival of neutrophilic iron-oxidizing bacteria

NASA Astrophysics Data System (ADS)

Saini, G.; Chan, C. S.

2011-12-01

Microbial growth in mineralizing environments depends on the cells' ability to evade surface precipitation. Cell-mineral interactions may be required for metabolism, but if unmoderated, cells could become encrusted, which would limit diffusion of nutrients and waste across cell walls. A combination of cell surface charge and hydrophobicity could enable the survival of microbes in such environments by inhibiting mineral attachment. To investigate this mechanism, we characterized the surfaces of two neutrophilic iron-oxidizing bacteria (FeOB): Mariprofundus ferrooxydans, a Zetaproteobacterium from Fe(II)-rich submarine hydrothermal vents and a Betaproteobacterium Gallionellales strain R-1, recently isolated from a ferrous groundwater seep. Both bacteria produce iron oxyhydroxides, yet successfully escape surface encrustation while inhabiting milieu where iron minerals are also produced by abiotic processes. SEM-EDX and TEM-EELS analyses of cultured bacteria revealed no iron on the cell surfaces. Zeta potential measurements showed that these bacteria have very small negative surface charge (0 to -4 mV) over a pH range of 4-9, indicating near-neutrally charged surfaces. Water contact angle measurements and thermodynamic calculations demonstrate that both bacteria and abiotically-formed Fe oxhydroxides are hydrophilic. Extended-DLVO calculations showed that hydrophilic repulsion between cells and minerals dominates over electrostatic and Lifshitz-van der Waals interactions. This leads to overall repulsion between microbes and minerals, thus preventing surface encrustation. Low surface charge and hydrophilicity (determined by microbial adhesion to hydrocarbon assay) were common features for both live and azide-inhibited cells, which shows that surface characteristics do not depend on active metabolism. It is remarkable that these two phylogenetically-distant bacteria from different environments employ similar adaptations to prevent surface mineralization. Our results confirm that surface characteristics can be a mechanism for survival in mineralizing environments. We predict that biotechnological applications such as bioremediation and microbial mineral carbon sequestration will benefit from microbes that can similarly avoid encrustation.

Evaluating the efficacy of subcellular fractionation of blast cells using live cell labeling and 2D DIGE.

PubMed

Ho, Yin Ying; Penno, Megan; Perugini, Michelle; Lewis, Ian; Hoffmann, Peter

2012-01-01

Labeling of exposed cell surface proteins of live cells using CyDye DIGE fluor minimal dyes is an efficient strategy for cell surface proteome profiling and quantifying differentially expressed proteins in diseases. Here we describe a strategy to evaluate a two-step detergent-based protein fractionation method using live cell labeling followed by visualization of the fluorescently labeled cell surface proteins and fractionated proteins within a single 2D gel.

Comparative evaluation of the three different surface treatments - conventional, laser and Nano technology methods in enhancing the surface characteristics of commercially pure titanium discs and their effects on cell adhesion: An in vitro study.

PubMed

Vignesh; Nayar, Sanjna; Bhuminathan; Mahadevan; Santhosh, S

2015-04-01

The surface area of the titanium dental implant materials can be increased by surface treatments without altering their shape and form, thereby increasing the biologic properties of the biomaterial. A good biomaterial helps in early cell adhesion and cell signaling. In this study, the commercially pure titanium surfaces were prepared to enable machined surfaces to form a control material and to be compared with sandblasted and acid-etched surfaces, laser treated surfaces and titanium dioxide (20 nm) Nano-particle coated surfaces. The surface elements were characterized. The biocompatibility was evaluated by cell culture in vitro using L929 fibroblasts. The results suggested that the titanium dioxide Nano-particle coated surfaces had good osteoconductivity and can be used as a potential method for coating the biomaterial.

Immunocytochemistry of cell surface heparan sulfate proteoglycan in mouse tissues. A light and electron microscopic study.

PubMed

Hayashi, K; Hayashi, M; Jalkanen, M; Firestone, J H; Trelstad, R L; Bernfield, M

1987-10-01

The core protein of the proteoglycan at the cell surface of NMuMG mouse mammary epithelial cells bears both heparan and chondroitin sulfate chains and is recognized by the monoclonal antibody 281-2. Using this antibody and the peroxidase-antiperoxidase staining technique in adult mouse tissues, we found that the antibody recognizes the antigen in a highly restricted distribution, staining a variety of epithelial cells but no cells derived from embryonic mesoderm or neural crest. The antibody fails to stain any stromal (mesenchymal) or neuronal cells, with the exception of plasma cells and Leydig cells. Squamous and transitional epithelia stain intensely over their entire surfaces, whereas cuboidal and columnar epithelia stain moderately and only at the lateral surface of the basal cells. Within squamous and transitional epithelial tissues that undergo physiological regeneration (e.g., epidermis), the most superficial and differentiated cell types fail to stain. Within glandular and branched epithelia (e.g., pancreas), the secretory alveolar cells fail to stain. When evaluated by electron microscopy, granular deposits of stain are seen on the plasma membrane, especially on lateral surfaces, but none are noted within the cells or the basement membrane. These results indicate that in adult tissues the core protein of this heparan sulfate-rich proteoglycan is expressed almost exclusively at epithelial cell surfaces. Expression appears to be lost as the cells become either mature or highly differentiated.

Antagonistic Regulation of Cystic Fibrosis Transmembrane Conductance Regulator Cell Surface Expression by Protein Kinases WNK4 and Spleen Tyrosine Kinase ▿

PubMed Central

Mendes, Ana Isabel; Matos, Paulo; Moniz, Sónia; Luz, Simão; Amaral, Margarida D.; Farinha, Carlos M.; Jordan, Peter

2011-01-01

Members of the WNK (with-no-lysine [K]) subfamily of protein kinases regulate various ion channels involved in sodium, potassium, and chloride homeostasis by either inducing their phosphorylation or regulating the number of channel proteins expressed at the cell surface. Here, we describe findings demonstrating that the cell surface expression of the cystic fibrosis transmembrane conductance regulator (CFTR) is also regulated by WNK4 in mammalian cells. This effect of WNK4 is independent of the presence of kinase and involves interaction with and inhibition of spleen tyrosine kinase (Syk), which phosphorylates Tyr512 in the first nucleotide-binding domain 1 (NBD1) of CFTR. Transfection of catalytically active Syk into CFTR-expressing baby hamster kidney cells reduces the cell surface expression of CFTR, whereas that of WNK4 promotes it. This is shown by biotinylation of cell surface proteins, immunofluorescence microscopy, and functional efflux assays. Mutation of Tyr512 to either glutamic acid or phenylalanine is sufficient to alter CFTR surface levels. In human airway epithelial cells, downregulation of endogenous Syk and WNK4 confirms their roles as physiologic regulators of CFTR surface expression. Together, our results show that Tyr512 phosphorylation is a novel signal regulating the prevalence of CFTR at the cell surface and that WNK4 and Syk perform an antagonistic role in this process. PMID:21807898

In vitro mesenchymal stem cell response to a CO2 laser modified polymeric material.

PubMed

Waugh, D G; Hussain, I; Lawrence, J; Smith, G C; Cosgrove, D; Toccaceli, C

2016-10-01

With an ageing world population it is becoming significantly apparent that there is a need to produce implants and platforms to manipulate stem cell growth on a pharmaceutical scale. This is needed to meet the socio-economic demands of many countries worldwide. This paper details one of the first ever studies in to the manipulation of stem cell growth on CO2 laser surface treated nylon 6,6 highlighting its potential as an inexpensive platform to manipulate stem cell growth on a pharmaceutical scale. Through CO2 laser surface treatment discrete changes to the surfaces were made. That is, the surface roughness of the nylon 6,6 was increased by up to 4.3μm, the contact angle was modulated by up to 5° and the surface oxygen content increased by up to 1atom %. Following mesenchymal stem cell growth on the laser treated samples, it was identified that CO2 laser surface treatment gave rise to an enhanced response with an increase in viable cell count of up to 60,000cells/ml when compared to the as-received sample. The effect of surface parameters modified by the CO2 laser surface treatment on the mesenchymal stem cell response is also discussed along with potential trends that could be identified to govern the mesenchymal stem cell response. Copyright © 2016. Published by Elsevier B.V.

Modelling cell motility and chemotaxis with evolving surface finite elements

PubMed Central

Elliott, Charles M.; Stinner, Björn; Venkataraman, Chandrasekhar

2012-01-01

We present a mathematical and a computational framework for the modelling of cell motility. The cell membrane is represented by an evolving surface, with the movement of the cell determined by the interaction of various forces that act normal to the surface. We consider external forces such as those that may arise owing to inhomogeneities in the medium and a pressure that constrains the enclosed volume, as well as internal forces that arise from the reaction of the cells' surface to stretching and bending. We also consider a protrusive force associated with a reaction–diffusion system (RDS) posed on the cell membrane, with cell polarization modelled by this surface RDS. The computational method is based on an evolving surface finite-element method. The general method can account for the large deformations that arise in cell motility and allows the simulation of cell migration in three dimensions. We illustrate applications of the proposed modelling framework and numerical method by reporting on numerical simulations of a model for eukaryotic chemotaxis and a model for the persistent movement of keratocytes in two and three space dimensions. Movies of the simulated cells can be obtained from http://homepages.warwick.ac.uk/∼maskae/CV_Warwick/Chemotaxis.html. PMID:22675164

Yeast cell surface display: An efficient strategy for improvement of bioethanol fermentation performance.

PubMed

Chen, Xianzhong

2017-03-04

The cell surface serves as a functional interface between the inside and the outside of the cell. Within the past 20 y the ability of yeast (Saccharomyces cerevisiae) to display heterologous proteins on the cell surface has been demonstrated. Furthermore, S. cerevisiae has been both developed and applied in expression of various proteins on the cell surface. Using this novel and useful strategy, proteins and peptides of various kinds can be displayed on the yeast cell surface by fusing the protein of interest with the glycosylphosphatidylinositol (GPI)-anchoring system. Consolidated bioprocessing (CBP) using S. cerevisiae represents a promising technology for bioethanol production. However, further work is needed to improve the fermentation performance. There is some excellent previous research regarding construction of yeast biocatalyst using the surface display system to decrease cost, increase efficiency of ethanol production and directly utilize starch or biomass for fuel production. In this commentary, we reviewed the yeast surface display system and highlighted recent work. Additionally, the strategy for decrease of phytate phosphate content in dried distillers grains with solubles (DDGS) by display of phytase on the yeast cell surface is discussed.

Yeast cell surface display: An efficient strategy for improvement of bioethanol fermentation performance

PubMed Central

Chen, Xianzhong

2017-01-01

ABSTRACT The cell surface serves as a functional interface between the inside and the outside of the cell. Within the past 20 y the ability of yeast (Saccharomyces cerevisiae) to display heterologous proteins on the cell surface has been demonstrated. Furthermore, S. cerevisiae has been both developed and applied in expression of various proteins on the cell surface. Using this novel and useful strategy, proteins and peptides of various kinds can be displayed on the yeast cell surface by fusing the protein of interest with the glycosylphosphatidylinositol (GPI)-anchoring system. Consolidated bioprocessing (CBP) using S. cerevisiae represents a promising technology for bioethanol production. However, further work is needed to improve the fermentation performance. There is some excellent previous research regarding construction of yeast biocatalyst using the surface display system to decrease cost, increase efficiency of ethanol production and directly utilize starch or biomass for fuel production. In this commentary, we reviewed the yeast surface display system and highlighted recent work. Additionally, the strategy for decrease of phytate phosphate content in dried distillers grains with solubles (DDGS) by display of phytase on the yeast cell surface is discussed. PMID:27459271

Simple surface engineering of polydimethylsiloxane with polydopamine for stabilized mesenchymal stem cell adhesion and multipotency

PubMed Central

Chuah, Yon Jin; Koh, Yi Ting; Lim, Kaiyang; Menon, Nishanth V.; Wu, Yingnan; Kang, Yuejun

2015-01-01

Polydimethylsiloxane (PDMS) has been extensively exploited to study stem cell physiology in the field of mechanobiology and microfluidic chips due to their transparency, low cost and ease of fabrication. However, its intrinsic high hydrophobicity renders a surface incompatible for prolonged cell adhesion and proliferation. Plasma-treated or protein-coated PDMS shows some improvement but these strategies are often short-lived with either cell aggregates formation or cell sheet dissociation. Recently, chemical functionalization of PDMS surfaces has proved to be able to stabilize long-term culture but the chemicals and procedures involved are not user- and eco-friendly. Herein, we aim to tailor greener and biocompatible PDMS surfaces by developing a one-step bio-inspired polydopamine coating strategy to stabilize long-term bone marrow stromal cell culture on PDMS substrates. Characterization of the polydopamine-coated PDMS surfaces has revealed changes in surface wettability and presence of hydroxyl and secondary amines as compared to uncoated surfaces. These changes in PDMS surface profile contribute to the stability in BMSCs adhesion, proliferation and multipotency. This simple methodology can significantly enhance the biocompatibility of PDMS-based microfluidic devices for long-term cell analysis or mechanobiological studies. PMID:26647719

Profound re-organization of cell surface proteome in equine retinal pigment epithelial cells in response to in vitro culturing.

PubMed

Szober, Christoph M; Hauck, Stefanie M; Euler, Kerstin N; Fröhlich, Kristina J H; Alge-Priglinger, Claudia; Ueffing, Marius; Deeg, Cornelia A

2012-10-31

The purpose of this study was to characterize the cell surface proteome of native compared to cultured equine retinal pigment epithelium (RPE) cells. The RPE plays an essential role in visual function and represents the outer blood-retinal barrier. We are investigating immunopathomechanisms of equine recurrent uveitis, an autoimmune inflammatory disease in horses leading to breakdown of the outer blood-retinal barrier and influx of autoreactive T-cells into affected horses' vitrei. Cell surface proteins of native and cultured RPE cells from eye-healthy horses were captured by biotinylation, analyzed by high resolution mass spectrometry coupled to liquid chromatography (LC MS/MS), and the most interesting candidates were validated by PCR, immunoblotting and immunocytochemistry. A total of 112 proteins were identified, of which 84% were cell surface membrane proteins. Twenty-three of these proteins were concurrently expressed by both cell states, 28 proteins exclusively by native RPE cells. Among the latter were two RPE markers with highly specialized RPE functions: cellular retinaldehyde-binding protein (CRALBP) and retinal pigment epithelium-specific protein 65kDa (RPE65). Furthermore, 61 proteins were only expressed by cultured RPE cells and absent in native cells. As we believe that initiating events, leading to the breakdown of the outer blood-retinal barrier, take place at the cell surface of RPE cells as a particularly exposed barrier structure, this differential characterization of cell surface proteomes of native and cultured equine RPE cells is a prerequisite for future studies.

Cell-material interactions revealed via material techniques of surface patterning.

PubMed

Yao, Xiang; Peng, Rong; Ding, Jiandong

2013-10-04

Cell-material interactions constitute a key fundamental topic in biomaterials study. Various cell cues and matrix cues as well as soluble factors regulate cell behaviors on materials. These factors are coupled with each other as usual, and thus it is very difficult to unambiguously elucidate the role of each regulator. The recently developed material techniques of surface patterning afford unique ways to reveal the underlying science. This paper reviews the pertinent material techniques to fabricate patterns of microscale and nanoscale resolutions, and corresponding cell studies. Some issues are emphasized, such as cell localization on patterned surfaces of chemical contrast, and effects of cell shape, cell size, cell-cell contact, and seeding density on differentiation of stem cells. Material cues to regulate cell adhesion, cell differentiation and other cell events are further summed up. Effects of some physical properties, such as surface topography and matrix stiffness, on cell behaviors are also discussed; nanoscaled features of substrate surfaces to regulate cell fate are summarized as well. The pertinent work sheds new insight into the cell-material interactions, and is stimulating for biomaterial design in regenerative medicine, tissue engineering, and high-throughput detection, diagnosis, and drug screening. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Control of Cross Talk between Angiogenesis and Inflammation by Mesenchymal Stem Cells for the Treatment of Ocular Surface Diseases.

PubMed

Li, Fei; Zhao, Shao-Zhen

2016-01-01

Angiogenesis is beneficial in the treatment of ischemic heart disease and peripheral artery disease. However, it facilitates inflammatory cell filtration and inflammation cascade that disrupt the immune and angiogenesis privilege of the avascular cornea, resulting in ocular surface diseases and even vision loss. Although great progress has been achieved, healing of severe ocular surface injury and immunosuppression of corneal transplantation are the most difficult and challenging step in the treatment of ocular surface disorders. Mesenchymal stem cells (MSCs), derived from various adult tissues, are able to differentiate into different cell types such as endothelial cells and fat cells. Although it is still under debate whether MSCs could give rise to functional corneal cells, recent results from different study groups showed that MSCs could improve corneal disease recovery through suppression of inflammation and modulation of immune cells. Thus, MSCs could become a promising tool for ocular surface disorders. In this review, we discussed how angiogenesis and inflammation are orchestrated in the pathogenesis of ocular surface disease. We overviewed and updated the knowledge of MSCs and then summarized the therapeutic potential of MSCs via control of angiogenesis, inflammation, and immune response in the treatment of ocular surface disease.

Coaction of intercellular adhesion and cortical tension specifies tissue surface tension

PubMed Central

Manning, M. Lisa; Foty, Ramsey A.; Steinberg, Malcolm S.; Schoetz, Eva-Maria

2010-01-01

In the course of animal morphogenesis, large-scale cell movements occur, which involve the rearrangement, mutual spreading, and compartmentalization of cell populations in specific configurations. Morphogenetic cell rearrangements such as cell sorting and mutual tissue spreading have been compared with the behaviors of immiscible liquids, which they closely resemble. Based on this similarity, it has been proposed that tissues behave as liquids and possess a characteristic surface tension, which arises as a collective, macroscopic property of groups of mobile, cohering cells. But how are tissue surface tensions generated? Different theories have been proposed to explain how mesoscopic cell properties such as cell–cell adhesion and contractility of cell interfaces may underlie tissue surface tensions. Although recent work suggests that both may be contributors, an explicit model for the dependence of tissue surface tension on these mesoscopic parameters has been missing. Here we show explicitly that the ratio of adhesion to cortical tension determines tissue surface tension. Our minimal model successfully explains the available experimental data and makes predictions, based on the feedback between mechanical energy and geometry, about the shapes of aggregate surface cells, which we verify experimentally. This model indicates that there is a crossover from adhesion dominated to cortical-tension dominated behavior as a function of the ratio between these two quantities. PMID:20616053

Surface functionalization of nanobiomaterials for application in stem cell culture, tissue engineering, and regenerative medicine.

PubMed

Rana, Deepti; Ramasamy, Keerthana; Leena, Maria; Jiménez, Constanza; Campos, Javier; Ibarra, Paula; Haidar, Ziyad S; Ramalingam, Murugan

2016-05-01

Stem cell-based approaches offer great application potential in tissue engineering and regenerative medicine owing to their ability of sensing the microenvironment and respond accordingly (dynamic behavior). Recently, the combination of nanobiomaterials with stem cells has paved a great way for further exploration. Nanobiomaterials with engineered surfaces could mimic the native microenvironment to which the seeded stem cells could adhere and migrate. Surface functionalized nanobiomaterial-based scaffolds could then be used to regulate or control the cellular functions to culture stem cells and regenerate damaged tissues or organs. Therefore, controlling the interactions between nanobiomaterials and stem cells is a critical factor. However, surface functionalization or modification techniques has provided an alternative approach for tailoring the nanobiomaterials surface in accordance to the physiological surrounding of a living cells; thereby, enhancing the structural and functional properties of the engineered tissues and organs. Currently, there are a variety of methods and technologies available to modify the surface of biomaterials according to the specific cell or tissue properties to be regenerated. This review highlights the trends in surface modification techniques for nanobiomaterials and the biological relevance in stem cell-based tissue engineering and regenerative medicine. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:554-567, 2016. © 2016 American Institute of Chemical Engineers.

Gold cleaning methods for preparation of cell culture surfaces for self-assembled monolayers of zwitterionic oligopeptides.

PubMed

Enomoto, Junko; Kageyama, Tatsuto; Myasnikova, Dina; Onishi, Kisaki; Kobayashi, Yuka; Taruno, Yoko; Kanai, Takahiro; Fukuda, Junji

2018-05-01

Self-assembled monolayers (SAMs) have been used to elucidate interactions between cells and material surface chemistry. Gold surfaces modified with oligopeptide SAMs exhibit several unique characteristics, such as cell-repulsive surfaces, micropatterns of cell adhesion and non-adhesion regions for control over cell microenvironments, and dynamic release of cells upon external stimuli under culture conditions. However, basic procedures for the preparation of oligopeptide SAMs, including appropriate cleaning methods of the gold surface before modification, have not been fully established. Because gold surfaces are readily contaminated with organic compounds in the air, cleaning methods may be critical for SAM formation. In this study, we examined the effects of four gold cleaning methods: dilute aqua regia, an ozone water, atmospheric plasma, and UV irradiation. Among the methods, UV irradiation most significantly improved the formation of oligopeptide SAMs in terms of repulsion of cells on the surfaces. We fabricated an apparatus with a UV light source, a rotation table, and HEPA filter, to treat a number of gold substrates simultaneously. Furthermore, UV-cleaned gold substrates were capable of detaching cell sheets without serious cell injury. This may potentially provide a stable and robust approach to oligopeptide SAM-based experiments for biomedical studies. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Constrained ceramic-filled polymer armor

DOEpatents

Sandstrom, Donald J.; Calkins, Noel C.; Gac, Frank D.

1990-01-01

An armor system in which a plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material, which is a ceramic material in particulate form dispersed in a polymeric matrix.

Antifouling property of highly oleophobic substrates for solar cell surfaces

NASA Astrophysics Data System (ADS)

Fukada, Kenta; Nishizawa, Shingo; Shiratori, Seimei

2014-03-01

Reduction of solar cell conversion efficiency by bird spoor or oil smoke is a common issue. Maintaining the surface of solar cells clean to retain the incident light is of utmost importance. In this respect, there has been growing interest in the area of superhydrophobicity for developing water repelling and self-cleaning surfaces. This effect is inspired by lotus leaves that have micro papillae covered with hydrophobic wax nanostructures. Superhydrophobic surfaces on transparent substrates have been developed for removing contaminants from solar cell surfaces. However, oil cannot be removed by superhydrophobic effect. In contrast, to prevent bird spoor, a highly oleophobic surface is required. In a previous study, we reported transparent-type fabrics comprising nanoparticles with a nano/micro hierarchical structure that ensured both oleophobicity and transparency. In the current study, we developed new highly oleophobic stripes that were constructed into semi-transparent oleophobic surfaces for solar cells. Solar cell performance was successfully maintained; the total transmittance was a key factor for determining conversion efficiency.

Attachment of Escherichia coli O157:H7 grown in tryptic soy broth and nutrient broth to apple and lettuce surfaces as related to cell hydrophobicity, surface charge, and capsule production.

PubMed

Hassan, A N; Frank, J F

2004-10-01

This study investigated the effect of growth in tryptic soy broth (TSB) and nutrient broth (NB) on the ability Escherichia coli O157:H7 to attach to lettuce and apple surfaces. In addition, cell surface hydrophobicity, charge and capsule production were determined on cells grown in these media. Cells grown in NB attached less to lettuce and apple surfaces than did those grown in TSB. TSB, but not NB, supported capsule production by E. coli O157:H7. Cells grown in TSB were more hydrophilic than those grown in NB. No difference was found in the electrokinetic properties of cells grown in these media. Electrostatic and hydrophobic interactions and surface proteins did not appear to play an important role in the attachment of E. coli O157:H7 to these surfaces. Of the factors studied, only capsule production was associated with attachment ability. Copyright 2003 Elsevier B.V.

Bone Cell–materials Interactions and Ni Ion Release of Anodized Equiatomic NiTi Alloy

PubMed Central

Bernard, Sheldon A.; Balla, Vamsi Krishna; Davies, Neal M.; Bose, Susmita; Bandyopadhyay, Amit

2011-01-01

Laser processed NiTi alloy was anodized for different durations in H2SO4 electrolyte with varying pH to create biocompatible surfaces with low Ni ion release as well as bioactive surfaces to enhance biocompatibility and bone cell-materials interactions. The anodized surfaces were assessed for their in vitro cell-materials interactions using human fetal osteoblast (hFOB) cells for 3, 7 and 11 days, and Ni ion release up to 8 weeks in simulated body fluids. The results were correlated with surface morphologies of anodized surfaces characterized using field-emission scanning electron microscopy (FESEM). The results show that the anodization creates a surface with nano/micro roughness depending on anodization conditions. The hydrophilicity of NiTi surface was found to improve after anodization due to lower contact angles in cell media, which dropped from 32° to < 5°. The improved wettability of anodized surfaces is further corroborated by their high surface energy comparable to that of cp Ti. Relatively high surface energy, especially polar component, and nano/micro surface features of anodized surfaces significantly increased the number of living cells and their adherence and growth on these surfaces. Finally, a significant drop in Ni ion release from 268 ± 11 to 136 ± 15 ppb was observed for NiTi surfaces after anodization. This work indicates that anodization of NiTi alloy has a positive influence on the surface energy and surface morphology, which in turn improve bone cell-materials interactions and reduce Ni ion release in vitro. PMID:21232641

Analysis of the interaction of an electron beam with back surface field solar cells

NASA Technical Reports Server (NTRS)

Von Roos, O.; Luke, K. L.

1983-01-01

In this paper the short circuit current Isc induced by the electron beam of a scanning electron microscope in a back surface field solar cell will be determined theoretically. It will be shown that, in a configuration used previously for solar cells with an ohmic back surface, the Isc gives a convenient means for estimating the back surface recombination velocities and thus the quality of back surface field cells. Numerical data will be presented applicable to a point source model for the electron-hole pair generation.

Human mesenchymal stem cell behavior on femtosecond laser-textured Ti-6Al-4V surfaces.

PubMed

Cunha, Alexandre; Zouani, Omar Farouk; Plawinski, Laurent; Botelho do Rego, Ana Maria; Almeida, Amélia; Vilar, Rui; Durrieu, Marie-Christine

2015-01-01

The aim of the present work was to investigate ultrafast laser surface texturing as a surface treatment of Ti-6Al-4V alloy dental and orthopedic implants to improve osteoblastic commitment of human mesenchymal stem cells (hMSCs). Surface texturing was carried out by direct writing with an Yb:KYW chirped-pulse regenerative amplification laser system with a central wavelength of 1030 nm and a pulse duration of 500 fs. The surface topography and chemical composition were investigated by scanning electron microscopy and x-ray photoelectron spectroscopy, respectively. Three types of surface textures with potential interest to improve implant osseointegration can be produced by this method: laser-induced periodic surface structures (LIPSSs); nanopillars (NPs); and microcolumns covered with LIPSSs, forming a bimodal roughness distribution. The potential of the laser treatment in improving hMSC differentiation was assessed by in vitro study of hMSCs spreading, adhesion, elongation and differentiation using epifluorescence microscopy at different times after cell seeding, after specific stainings and immunostainings. Cell area and focal adhesion area were lower on the laser-textured surfaces than on a polished reference surface. Obviously, the laser-textured surfaces have an impact on cell shape. Osteoblastic commitment was observed independently of the surface topography after 2 weeks of cell seeding. When the cells were cultured (after 4 weeks of seeding) in osteogenic medium, LIPSS- and NP- textured surfaces enhanced matrix mineralization and bone-like nodule formation as compared with polished and microcolumn-textured surfaces. The present work shows that surface nanotextures consisting of LIPSSs and NPs can, potentially, improve hMSC differentiation into an osteoblastic lineage.

Topography and behavior of Sertoli cells in sparse culture during the transitional remodeling phase.

PubMed

Tung, P S; Choi, A H; Fritz, I B

1988-01-01

We report observations on the behavior of Sertoli cells in sparse culture during the period from the time of plating to the time of initial confluence (the transitional remodeling phase). Changes in shape, structure, and polarity of cells, as well as changes in migration patterns and cell-cell association patterns, have been followed during the transitional remodeling phase with the aid of topographical markers. These markers are based upon differences between ultrastructural features of the basolateral and apicolateral surfaces. The basolateral surface is characterized by plasmalemmal blebs, whereas the apicolateral surface is characterized by filopodial extensions. Structural differences observed in situ remain evident in Sertoli cells isolated by sequential enzymatic treatments that are described. Another marker is provided by laminin-binding sites, which are detected exclusively on the blebbed, basolateral surfaces of freshly prepared Sertoli cell aggregates. The orientation described is sustained during the initial radial migration of Sertoli cells explanted on uncoated glass coverslips. Under these conditions, blebs are detected only on the dorsal surfaces, and filopodial extensions are evident only on the ventral surfaces. In contrast, Sertoli cells sparsely plated on a reconstituted basement membrane (air-dried Matrigel) migrate rapidly, display an extraordinary capacity to form elaborate cytoplasmic extensions for cell-cell and cell-substratum contacts, and readily retract blebs and filopodial extensions. These cells do not form mosaic borders, whereas cells plated on uncoated glass do form a monolayer with mosaic-like borders. Cells sparsely seeded on gelated Matrigel migrate preferentially at gaps between adjacent cell explants, and develop a compact cell-cell association pattern. These cells display few, if any, cytoplasmic extensions. We compare the behavior of Sertoli cells sparsely plated on Matrigel with the behavior of Sertoli cells in situ during different stages of development.

Cell adhesion on nanotopography

NASA Astrophysics Data System (ADS)

Tsai, Irene; Kimura, Masahiro; Stockton, Rebecca; Jacobson, Bruce; Russell, Thomas

2003-03-01

Cell adhesion, a key element in understanding the cell-biomaterial interactions, underpins proper cell growth, function and survival. Understanding the parameters influencing cell adhesion is critical for applications in biosensors, implants and bioreactors. A gradient surface is used to study the effect of the surface topography on cell adhesion. A gradient surface is generated by block copolymer and homopolymer blends. The two homopolymers will phase separate on the micron scale and gradually decrease to nano-scale by the microphase separation of the diblock. Gradient surfaces offer a unique opportunity to probe lateral variations in the topography and interactions. Using thin films of mixtures of diblock copolymers of PS-b-MMA with PS and PMMA homopolymers, where the concentration of the PS-b-MMA varies across the surface, a gradient in the size scale of the morphology, from the nanoscopic to microscopic, was produced. By UV exposure, the variation in morphology translated into a variation in topography. The extent of cell spreading and cytoskeleton formation was investigated and marked dependence on the length scale of the surface topography was found.

Engineering live cell surfaces with functional polymers via cytocompatible controlled radical polymerization

NASA Astrophysics Data System (ADS)

Niu, Jia; Lunn, David J.; Pusuluri, Anusha; Yoo, Justin I.; O'Malley, Michelle A.; Mitragotri, Samir; Soh, H. Tom; Hawker, Craig J.

2017-06-01

The capability to graft synthetic polymers onto the surfaces of live cells offers the potential to manipulate and control their phenotype and underlying cellular processes. Conventional grafting-to strategies for conjugating preformed polymers to cell surfaces are limited by low polymer grafting efficiency. Here we report an alternative grafting-from strategy for directly engineering the surfaces of live yeast and mammalian cells through cell surface-initiated controlled radical polymerization. By developing cytocompatible PET-RAFT (photoinduced electron transfer-reversible addition-fragmentation chain-transfer polymerization), synthetic polymers with narrow polydispersity (Mw/Mn < 1.3) could be obtained at room temperature in 5 minutes. This polymerization strategy enables chain growth to be initiated directly from chain-transfer agents anchored on the surface of live cells using either covalent attachment or non-covalent insertion, while maintaining high cell viability. Compared with conventional grafting-to approaches, these methods significantly improve the efficiency of grafting polymer chains and enable the active manipulation of cellular phenotypes.

Phenotypic Heterogeneity and the Evolution of Bacterial Life Cycles

PubMed Central

van Gestel, Jordi; Nowak, Martin A.

2016-01-01

Most bacteria live in colonies, where they often express different cell types. The ecological significance of these cell types and their evolutionary origin are often unknown. Here, we study the evolution of cell differentiation in the context of surface colonization. We particularly focus on the evolution of a ‘sticky’ cell type that is required for surface attachment, but is costly to express. The sticky cells not only facilitate their own attachment, but also that of non-sticky cells. Using individual-based simulations, we show that surface colonization rapidly evolves and in most cases leads to phenotypic heterogeneity, in which sticky and non-sticky cells occur side by side on the surface. In the presence of regulation, cell differentiation leads to a remarkable set of bacterial life cycles, in which cells alternate between living in the liquid and living on the surface. The dominant life stage is formed by the surface-attached colony that shows many complex features: colonies reproduce via fission and by producing migratory propagules; cells inside the colony divide labour; and colonies can produce filaments to facilitate expansion. Overall, our model illustrates how the evolution of an adhesive cell type goes hand in hand with the evolution of complex bacterial life cycles. PMID:26894881

Corrosion of Mg alloy AZ91D in the presence of living cells.

PubMed

Seuss, F; Seuss, S; Turhan, M C; Fabry, B; Virtanen, S

2011-11-01

Mg and Mg alloys are of interest for biodegradable implants as they readily corrode in biological fluids, and dissolved Mg ions are nontoxic. Even though it is well known that Mg dissolution leads to pH increase in the surroundings, the effect of the corrosion-induced alkalization on the biological environment has not been studied in detail. We therefore explored the interactions between corrosion-induced pH increase and cell growth on Mg alloy AZ91D surface. Cell adhesion and spreading on the alloy surface is unimpeded initially. However, with time a large fraction of cells de-adhere. We attribute this to the observed increase of the pH in the cell culture medium in the process of alloy dissolution. Cytotoxicity tests with HeLa cells grown on glass surfaces confirm that cell death increases with increasing alkalinity of the cell culture medium. We also show that a the cells that adhere on the Mg alloy surface act as a corrosion-blocking surface layer. In consequence, a slower pH increase in the medium takes place when the alloy surface is covered with cells. Electrochemical impedance spectroscopy measurements (EIS) verify that a cell layer slows down the corrosion process. 2011 Wiley Periodicals, Inc.

Quantum Efficiency Loss after PID Stress: Wavelength Dependence on Cell Surface and Cell Edge

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

Oh, Jaewon; Bowden, Stuart; TamizhMani, GovindaSamy

2015-06-14

It is known that the potential induced degradation (PID) stress of conventional p-base solar cells affects power, shunt resistance, junction recombination, and quantum efficiency (QE). One of the primary solutions to address the PID issue is a modification of chemical and physical properties of antireflection coating (ARC) on the cell surface. Depending on the edge isolation method used during cell processing, the ARC layer near the edges may be uniformly or non-uniformly damaged. Therefore, the pathway for sodium migration from glass to the cell junction could be either through all of the ARC surface if surface and edge ARC havemore » low quality or through the cell edge if surface ARC has high quality but edge ARC is defective due to certain edge isolation process. In this study, two PID susceptible cells from two different manufacturers have been investigated. The QE measurements of these cells before and after PID stress were performed at both surface and edge. We observed the wavelength dependent QE loss only in the first manufacturer's cell but not in the second manufacturer's cell. The first manufacturer's cell appeared to have low quality ARC whereas the second manufacturer's cell appeared to have high quality ARC with defective edge. To rapidly screen a large number of cells for PID stress testing, a new but simple test setup that does not require laminated cell coupon has been developed and is used in this investigation.« less

Characteristic Changes in Cell Surface Glycosylation Accompany Intestinal Epithelial Cell (IEC) Differentiation: High Mannose Structures Dominate the Cell Surface Glycome of Undifferentiated Enterocytes*

PubMed Central

Park, Dayoung; Brune, Kristin A.; Mitra, Anupam; Marusina, Alina I.; Maverakis, Emanual; Lebrilla, Carlito B.

2015-01-01

Changes in cell surface glycosylation occur during the development and differentiation of cells and have been widely correlated with the progression of several diseases. Because of their structural diversity and sensitivity to intra- and extracellular conditions, glycans are an indispensable tool for analyzing cellular transformations. Glycans present on the surface of intestinal epithelial cells (IEC) mediate interactions with billions of native microorganisms, which continuously populate the mammalian gut. A distinct feature of IECs is that they differentiate as they migrate upwards from the crypt base to the villus tip. In this study, nano-LC/ESI QTOF MS profiling was used to characterize the changes in glycosylation that correspond to Caco-2 cell differentiation. As Caco-2 cells differentiate to form a brush border membrane, a decrease in high mannose type glycans and a concurrent increase in fucosylated and sialylated complex/hybrid type glycans were observed. At day 21, when cells appear to be completely differentiated, remodeling of the cell surface glycome ceases. Differential expression of glycans during IEC maturation appears to play a key functional role in regulating the membrane-associated hydrolases and contributes to the mucosal surface innate defense mechanisms. Developing methodologies to rapidly identify changes in IEC surface glycans may lead to a rapid screening approach for a variety of disease states affecting the GI tract. PMID:26355101

Cell behavior related to implant surfaces with different microstructure and chemical composition: an in vitro analysis.

PubMed

Conserva, Enrico; Lanuti, Anna; Menini, Maria

2010-01-01

This paper reports on an in vitro comparison of osteoblast and mesenchymal stem cell (MSC) adhesion, proliferation, and differentiation related to two different surface treatments applied to the same implant design to determine whether the interaction between cells and implants is influenced by surface structure and chemical composition of the implants. Thirty-nine implants with a sandblasted (SB) surface and 39 implants with a grit-blasted and high-temperature acid-etched (GBAE) surface were used. The implant macrostructures and microstructures were analyzed by high- and low-voltage scanning electron microscopy (SEM) and by stereo-SEM. The surface chemical composition was investigated by energy dispersive analysis and x-ray photoemission spectroscopy. SaOS-2 osteoblasts and human MSCs were used for the evaluation of cell proliferation and alkaline phosphatase enzymatic activity in contact with the two surfaces. The GBAE surface showed fewer contaminants and a very high percentage of titanium (19.7%) compared to the SB surface (14.2%). The two surfaces showed similar mean roughness (Ra), but the depth (Rz) and density (RSm) of the porosity were significantly increased in the GBAE surface. The GBAE surface presented more osteoblast and MSC proliferation than the SB surface. No statistically significant differences in alkaline phosphatase activity were found between surfaces for either cellular line. The GBAE surface showed less surface contaminants and a higher percentage of titanium (19.7%) than the SB surface. The macro/micropore structured design and chemical composition of the GBAE surface allowed greater cell adhesion and proliferation and an earlier cell spreading but did not play an obvious role in in vitro cellular differentiation.

Bioinspired Pollen-Like Hierarchical Surface for Efficient Recognition of Target Cancer Cells.

PubMed

Wang, Wenshuo; Yang, Gao; Cui, Haijun; Meng, Jingxin; Wang, Shutao; Jiang, Lei

2017-08-01

The efficient recognition and isolation of rare cancer cells holds great promise for cancer diagnosis and prognosis. In nature, pollens exploit spiky structures to realize recognition and adhesion to stigma. Herein, a bioinspired pollen-like hierarchical surface is developed by replicating the assembly of pollen grains, and efficient and specific recognition to target cancer cells is achieved. The pollen-like surface is fabricated by combining filtering-assisted assembly and soft lithography-based replication of pollen grains of wild chrysanthemum. After modification with a capture agent specific to cancer cells, the pollen-like surface enables the capture of target cancer cells with high efficiency and specificity. In addition, the pollen-like surface not only assures high viability of captured cells but also performs well in cell mixture system and at low cell density. This study represents a good example of constructing cell recognition biointerfaces inspired by pollen-stigma adhesion. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using the two-way shape memory effect of NiTi to control surface texture for cellular mechanotransduction

NASA Astrophysics Data System (ADS)

Liang, Yuan; Qin, Haifeng; Hou, Xiaoning; Doll, Gary L.; Ye, Chang; Dong, Yalin

2018-07-01

Mechanical force can crucially affect form and function of cells, and play critical roles in many diseases. While techniques to conveniently apply mechanical force to cells are limited, we fabricate a surface actuator prototype for cellular mechanotransduction by imparting severe plastic deformation into the surface of shape memory alloy (SMA). Using ultrasonic nanocrystal surface modification (UNSM), a deformation-based surface engineering technique with high controllability, micro surface patterns can be generated on the surface of SMA so that the micro-size cell can conform to the pattern; meanwhile, phase transformation can be induced in the subsurface by severe plastic deformation. By controlling plastic deformation and phase transformation, it is possible to establish a quantitative relation between deformation and temperature. When cells are cultured on the UNSM-treated surface, such surface can dynamically deform in response to external temperature change, and therefore apply controllable mechanical force to cells. Through this study, we demonstrate a novel way to fabricate a low-cost surface actuator that has the potential to be used for high-throughput cellular mechanotransduction.

Nano- and microstructured materials for in vitro studies of the physiology of vascular cells

PubMed Central

Chen, Hao; Biela, Sarah A; Kaufmann, Dieter

2016-01-01

The extracellular environment of vascular cells in vivo is complex in its chemical composition, physical properties, and architecture. Consequently, it has been a great challenge to study vascular cell responses in vitro, either to understand their interaction with their native environment or to investigate their interaction with artificial structures such as implant surfaces. New procedures and techniques from materials science to fabricate bio-scaffolds and surfaces have enabled novel studies of vascular cell responses under well-defined, controllable culture conditions. These advancements are paving the way for a deeper understanding of vascular cell biology and materials–cell interaction. Here, we review previous work focusing on the interaction of vascular smooth muscle cells (SMCs) and endothelial cells (ECs) with materials having micro- and nanostructured surfaces. We summarize fabrication techniques for surface topographies, materials, geometries, biochemical functionalization, and mechanical properties of such materials. Furthermore, various studies on vascular cell behavior and their biological responses to micro- and nanostructured surfaces are reviewed. Emphasis is given to studies of cell morphology and motility, cell proliferation, the cytoskeleton and cell-matrix adhesions, and signal transduction pathways of vascular cells. We finalize with a short outlook on potential interesting future studies. PMID:28144512

Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth.

PubMed

Jarisz, Tasha A; Lane, Sarah; Gozdzialski, Lea; Hore, Dennis K

2018-06-14

Surface-specific nonlinear vibrational spectroscopy, combined with bulk solution measurements and imaging, is used to study the surface conditions during the growth of E. coli. As a result of the silica high surface charge density, the water structure at the silica-aqueous interface is known to be especially sensitive to pH and ionic strength, and surface concentration profiles develop that can be appreciably different from the bulk solution conditions. We illustrate that, in the presence of growing cells, a unique surface micro-environment is established as a result of metabolites accumulating on the silica surface. Even in the subsequent absence of the cells, this surface layer works to reduce the interfacial ionic strength as revealed by the enhanced signal from surface water molecules. In the presence of growing cells, an additional boost in surface water signal is attributed to a local pH that is higher than that of the bulk solution.

Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth

NASA Astrophysics Data System (ADS)

Jarisz, Tasha A.; Lane, Sarah; Gozdzialski, Lea; Hore, Dennis K.

2018-06-01

Surface-specific nonlinear vibrational spectroscopy, combined with bulk solution measurements and imaging, is used to study the surface conditions during the growth of E. coli. As a result of the silica high surface charge density, the water structure at the silica-aqueous interface is known to be especially sensitive to pH and ionic strength, and surface concentration profiles develop that can be appreciably different from the bulk solution conditions. We illustrate that, in the presence of growing cells, a unique surface micro-environment is established as a result of metabolites accumulating on the silica surface. Even in the subsequent absence of the cells, this surface layer works to reduce the interfacial ionic strength as revealed by the enhanced signal from surface water molecules. In the presence of growing cells, an additional boost in surface water signal is attributed to a local pH that is higher than that of the bulk solution.

Functional Analysis of CD28/B7 and CD40/CD40L Costimulation During the in vivo Type 2 Immune Response

DTIC Science & Technology

1995-10-06

these activation markers on B cells and changes in B cell size (forward light scatter) were analyzed by flow cytometry (Figure 7). B cell surface B7...activation ofnaive CD4+ Th cells requires two signals delivered from antigen presenting cells (APes). The engagement ofthe T cell surface receptor...shown that T cell surface ii molecule CD28, and its homologue CTLA-4, can provide costimulatory signals to 10 cells when they interact with their ligands

A Unique Procedure to Identify Cell Surface Markers Through a Spherical Self-Organizing Map Applied to DNA Microarray Analysis.

PubMed

Sugii, Yuh; Kasai, Tomonari; Ikeda, Masashi; Vaidyanath, Arun; Kumon, Kazuki; Mizutani, Akifumi; Seno, Akimasa; Tokutaka, Heizo; Kudoh, Takayuki; Seno, Masaharu

2016-01-01

To identify cell-specific markers, we designed a DNA microarray platform with oligonucleotide probes for human membrane-anchored proteins. Human glioma cell lines were analyzed using microarray and compared with normal and fetal brain tissues. For the microarray analysis, we employed a spherical self-organizing map, which is a clustering method suitable for the conversion of multidimensional data into two-dimensional data and displays the relationship on a spherical surface. Based on the gene expression profile, the cell surface characteristics were successfully mirrored onto the spherical surface, thereby distinguishing normal brain tissue from the disease model based on the strength of gene expression. The clustered glioma-specific genes were further analyzed by polymerase chain reaction procedure and immunocytochemical staining of glioma cells. Our platform and the following procedure were successfully demonstrated to categorize the genes coding for cell surface proteins that are specific to glioma cells. Our assessment demonstrates that a spherical self-organizing map is a valuable tool for distinguishing cell surface markers and can be employed in marker discovery studies for the treatment of cancer.

Heat shock 70-kDa protein 8 isoform 1 is expressed on the surface of human embryonic stem cells and downregulated upon differentiation.

PubMed

Son, Yeon Sung; Park, Jae Hyun; Kang, Young Kook; Park, Jin-Sung; Choi, Hong Seo; Lim, Ji Young; Lee, Jeoung Eun; Lee, Jung Bok; Ko, Myoung Seok; Kim, Yong-Sam; Ko, Jeong-Heon; Yoon, Hyun Soo; Lee, Kwang-Woong; Seong, Rho Hyun; Moon, Shin Yong; Ryu, Chun Jeih; Hong, Hyo Jeong

2005-01-01

The cell-surface markers used routinely to define the undifferentiated state and pluripotency of human embryonic stem cells (hESCs) are those used in mouse embryonic stem cells (mESCs) because of a lack of markers directly originated from hESC itself. To identify more hESC-specific cell-surface markers, we generated a panel of monoclonal antibodies (MAbs) by immunizing the irradiated cell clumps of hESC line Miz-hES1, and selected 26 MAbs that were able to bind to Miz-hES1 cells but not to mESCs, mouse embryonic fibroblast cells, and STO cells. Most antibodies did not bind to human neural progenitor cells derived from the Miz-hES1 cells, either. Of these, MAb 20-202S (IgG1, kappa) immunoprecipitated a cell-surface protein of 72-kDa from the lysate of biotin-labeled Miz-hES1 cells, which was identified to be heat shock 70-kDa protein 8 isoform 1 (HSPA8) by quadrupole time-of-flight tandem mass spectrometry. Immunocytochemical analyses proved that the HSPA8 protein was also present on the surface of hESC lines Miz-hES4, Miz-hES6, and HSF6. Two-color flow cytometric analysis of Miz-hES1 and HSF6 showed the coexpression of the HSPA8 protein with other hESC markers such as stage-specific embryonic antigen 3 (SSEA3), SSEA4, TRA-1-60, and TRA-1-81. Flow cytometric and Western blot analyses using various cells showed that MAb 20-202S specifically bound to the HSPA8 protein on the surface of Miz-hES1, contrary to other anti-HSP70 antibodies examined. Furthermore, the surface expression of the HSPA8 protein on Miz-hES1 was markedly downregulated upon differentiation. These data indicate that a novel MAb 20-202S recognizes the HSPA8 protein on the surface of hESCs and suggest that the HSPA8 protein is a putative cell-surface marker for undifferentiated hESCs.

Display of a β-mannanase and a chitosanase on the cell surface of Lactobacillus plantarum towards the development of whole-cell biocatalysts.

PubMed

Nguyen, Hoang-Minh; Mathiesen, Geir; Stelzer, Elena Maria; Pham, Mai Lan; Kuczkowska, Katarzyna; Mackenzie, Alasdair; Agger, Jane W; Eijsink, Vincent G H; Yamabhai, Montarop; Peterbauer, Clemens K; Haltrich, Dietmar; Nguyen, Thu-Ha

2016-10-04

Lactobacillus plantarum is considered as a potential cell factory because of its GRAS (generally recognized as safe) status and long history of use in food applications. Its possible applications include in situ delivery of proteins to a host, based on its ability to persist at mucosal surfaces of the human intestine, and the production of food-related enzymes. By displaying different enzymes on the surface of L. plantarum cells these could be used as whole-cell biocatalysts for the production of oligosaccharides. In this present study, we aimed to express and display a mannanase and a chitosanase on the cell surface of L. plantarum. ManB, a mannanase from Bacillus licheniformis DSM13, and CsnA, a chitosanase from Bacillus subtilis ATCC 23857 were fused to different anchoring motifs of L. plantarum for covalent attachment to the cell surface, either via an N-terminal lipoprotein anchor (Lp_1261) or a C-terminal cell wall anchor (Lp_2578), and the resulting fusion proteins were expressed in L. plantarum WCFS1. The localization of the recombinant proteins on the bacterial cell surface was confirmed by flow cytometry and immunofluorescence microscopy. The highest mannanase and chitosanase activities obtained for displaying L. plantarum cells were 890 U and 1360 U g dry cell weight, respectively. In reactions with chitosan and galactomannans, L. plantarum CsnA- and ManB-displaying cells produced chito- and manno-oligosaccharides, respectively, as analyzed by high performance anion exchange chromatography (HPAEC) and mass spectrometry (MS). Surface-displayed ManB is able to break down galactomannan (LBG) into smaller manno-oligosaccharides, which can support growth of L. plantarum. This study shows that mannanolytic and chitinolytic enzymes can be anchored to the cell surface of L. plantarum in active forms. L. plantarum chitosanase- and mannanase-displaying cells should be of interest for the production of potentially 'prebiotic' oligosaccharides. This approach, with the enzyme of interest being displayed on the cell surface of a food-grade organism, may also be applied in production processes relevant for food industry.

DNA-cell conjugates

DOEpatents

Hsiao, Shih-Chia; Francis, Matthew B.; Bertozzi, Carolyn; Mathies, Richard; Chandra, Ravi; Douglas, Erik; Twite, Amy; Toriello, Nicholas; Onoe, Hiroaki

2016-05-03

The present invention provides conjugates of DNA and cells by linking the DNA to a native functional group on the cell surface. The cells can be without cell walls or can have cell walls. The modified cells can be linked to a substrate surface and used in assay or bioreactors.

DNA-cell conjugates

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

Hsiao, Shih-Chia; Francis, Matthew B.; Bertozzi, Carolyn

The present invention provides conjugates of DNA and cells by linking the DNA to a native functional group on the cell surface. The cells can be without cell walls or can have cell walls. The modified cells can be linked to a substrate surface and used in assay or bioreactors.

Flagellin based biomimetic coatings: From cell-repellent surfaces to highly adhesive coatings.

PubMed

Kovacs, Boglarka; Patko, Daniel; Szekacs, Inna; Orgovan, Norbert; Kurunczi, Sandor; Sulyok, Attila; Khanh, Nguyen Quoc; Toth, Balazs; Vonderviszt, Ferenc; Horvath, Robert

2016-09-15

Biomimetic coatings with cell-adhesion-regulating functionalities are intensively researched today. For example, cell-based biosensing for drug development, biomedical implants, and tissue engineering require that the surface adhesion of living cells is well controlled. Recently, we have shown that the bacterial flagellar protein, flagellin, adsorbs through its terminal segments to hydrophobic surfaces, forming an oriented monolayer and exposing its variable D3 domain to the solution. Here, we hypothesized that this nanostructured layer is highly cell-repellent since it mimics the surface of the flagellar filaments. Moreover, we proposed flagellin as a carrier molecule to display the cell-adhesive RGD (Arg-Gly-Asp) peptide sequence and induce cell adhesion on the coated surface. The D3 domain of flagellin was replaced with one or more RGD motifs linked by various oligopeptides modulating flexibility and accessibility of the inserted segment. The obtained flagellin variants were applied to create surface coatings inducing cell adhesion and spreading to different levels, while wild-type flagellin was shown to form a surface layer with strong anti-adhesive properties. As reference surfaces synthetic polymers were applied which have anti-adhesive (PLL-g-PEG poly(l-lysine)-graft-poly(ethylene glycol)) or adhesion inducing properties (RGD-functionalized PLL-g-PEG). Quantitative adhesion data was obtained by employing optical biochips and microscopy. Cell-adhesion-regulating coatings can be simply formed on hydrophobic surfaces by using the developed flagellin-based constructs. The developed novel RGD-displaying flagellin variants can be easily obtained by bacterial production and can serve as alternatives to create cell-adhesion-regulating biomimetic coatings. In the present work, we show for the first time that. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Treatment of poly(ethylene terephthalate) foils by atmospheric pressure air dielectric barrier discharge and its influence on cell growth

NASA Astrophysics Data System (ADS)

Kuzminova, Anna; Vandrovcová, Marta; Shelemin, Artem; Kylián, Ondřej; Choukourov, Andrei; Hanuš, Jan; Bačáková, Lucie; Slavínská, Danka; Biederman, Hynek

2015-12-01

In this contribution an effect of dielectric barrier discharge (DBD) sustained in air at atmospheric pressure on surface properties of poly(ethylene terephthalate) (PET) foils is studied. It is found that exposure of PET to DBD plasma leads to rapid changes of surface chemical composition, wettability, surface morphology as well as mechanical properties of PET surface. In addition, based on biological tests that were performed using two cell types (Saos-2 human osteoblast-like cells and HUVEC human umbilical vein endothelial cells), it may be concluded that DBD plasma treatment positively influences cell growth on PET. This effect was found to be connected predominantly with increased surface energy and oxygen content of the surface of treated PET foils.

UV laser-ablated surface textures as potential regulator of cellular response.

PubMed

Chandra, Prafulla; Lai, Karen; Sung, Hak-Joon; Murthy, N Sanjeeva; Kohn, Joachim

2010-06-01

Textured surfaces obtained by UV laser ablation of poly(ethylene terephthalate) films were used to study the effect of shape and spacing of surface features on cellular response. Two distinct patterns, cones and ripples with spacing from 2 to 25 μm, were produced. Surface features with different shapes and spacings were produced by varying pulse repetition rate, laser fluence, and exposure time. The effects of the surface texture parameters, i.e., shape and spacing, on cell attachment, proliferation, and morphology of neonatal human dermal fibroblasts and mouse fibroblasts were studied. Cell attachment was the highest in the regions with cones at ∼4 μm spacing. As feature spacing increased, cell spreading decreased, and the fibroblasts became more circular, indicating a stress-mediated cell shrinkage. This study shows that UV laser ablation is a useful alternative to lithographic techniques to produce surface patterns for controlling cell attachment and growth on biomaterial surfaces.

The Effects of Size, Shape, and Surface Functional Group of Gold Nanostructures on Their Adsorption and Internalization by Cells

PubMed Central

Cho, Eun Chul; Au, Leslie; Zhang, Qiang; Xia, Younan

2010-01-01

In this study, we examined the effects of size, shape, and surface chemistry of gold nanostructures on their uptake (including both adsorption and internalization) by SK-BR-3 breast cancer cells. We used both spherical and cubic Au nanostructures (nanospheres and nanocages, respectively) of two different sizes, and their surface was modified with poly(ethylene glycol) (PEG), antibody anti-HER2, or poly(allyamine hydrochloride) (PAA). Our results showed that the size of the Au nanostructures influenced their uptake by the cells in a similar way regardless of the surface chemistry, while the shape dependency could vary depending on the surface functional group. In addition, the cells preferred to take up the Au nanostructures covered by different surface groups in the following order: PAA>> anti-HER2> PEG. The fraction of Au nanostructures attached to the cell surface was also dependent on the aforementioned parameters. PMID:20029850

Surface Mechanoengineering of a Zr-based Bulk Metallic Glass via Ar-Nanobubble Doping to Probe Cell Sensitivity to Rigid Materials

DOE PAGES

Huang, Lu; Tian, Mengkun; Wu, Dong; ...

2017-11-24

In this paper, a new materials platform, utilizing the amorphous microstructure of bulk metallic glasses (BMGs) and the versatility of ion implantation, was developed for the fundamental investigation of cell responses to substrate-rigidity variations in the gigapascal modulus range, which was previously unattainable with polymeric materials. The surface rigidity of a Zr-Al- Ni-Cu-Y BMG was modulated with low-energy Ar-ion implantation owing to the impartment of Ar nanobubbles into the amorphous matrix. Surface softening was achieved due to the formation of nanobubble-doped transitional zones in the Zrbased BMG substrate. Bone-forming cell studies on this newly designed platform demonstrated that mechanical cues,more » accompanied with the potential effects of other surface properties (i.e. roughness, morphology, and chemistry), contributed to modulating cell behaviors. Cell adhesion and actin filaments were found to be less established on less stiff surfaces, especially on the surface with an elastic modulus of 51 GPa. Cell growth appeared to be affected by surface mechanical properties. A lower stiffness was generally related to a higher growth rate. Findings in this study broadened our fundamental understanding concerning the mechanosensing of bone cells on stiff substrates. It also suggests that surface mechano-engineering of metallic materials could be a potential strategy to promote osseointegration of such materials for bone-implant applications. Further investigations are proposed to fine tune the ion implantation variables in order to further distinguish the surface-mechanical effect on bone-forming cell activities from the contributions of other surface properties.« less

Surface Mechanoengineering of a Zr-based Bulk Metallic Glass via Ar-Nanobubble Doping to Probe Cell Sensitivity to Rigid Materials

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

Huang, Lu; Tian, Mengkun; Wu, Dong

In this paper, a new materials platform, utilizing the amorphous microstructure of bulk metallic glasses (BMGs) and the versatility of ion implantation, was developed for the fundamental investigation of cell responses to substrate-rigidity variations in the gigapascal modulus range, which was previously unattainable with polymeric materials. The surface rigidity of a Zr-Al- Ni-Cu-Y BMG was modulated with low-energy Ar-ion implantation owing to the impartment of Ar nanobubbles into the amorphous matrix. Surface softening was achieved due to the formation of nanobubble-doped transitional zones in the Zrbased BMG substrate. Bone-forming cell studies on this newly designed platform demonstrated that mechanical cues,more » accompanied with the potential effects of other surface properties (i.e. roughness, morphology, and chemistry), contributed to modulating cell behaviors. Cell adhesion and actin filaments were found to be less established on less stiff surfaces, especially on the surface with an elastic modulus of 51 GPa. Cell growth appeared to be affected by surface mechanical properties. A lower stiffness was generally related to a higher growth rate. Findings in this study broadened our fundamental understanding concerning the mechanosensing of bone cells on stiff substrates. It also suggests that surface mechano-engineering of metallic materials could be a potential strategy to promote osseointegration of such materials for bone-implant applications. Further investigations are proposed to fine tune the ion implantation variables in order to further distinguish the surface-mechanical effect on bone-forming cell activities from the contributions of other surface properties.« less

Association of Cell Surface Mucins with Galectin-3 Contributes to the Ocular Surface Epithelial Barrier*

PubMed Central

Argüeso, Pablo; Guzman-Aranguez, Ana; Mantelli, Flavio; Cao, Zhiyi; Ricciuto, Jessica; Panjwani, Noorjahan

2009-01-01

Maintenance of an intact mucosal barrier is critical to preventing damage to and infection of wet-surfaced epithelia. The mechanism of defense has been the subject of much investigation, and there is evidence now implicating O-glycosylated mucins on the epithelial cell surface. Here we investigate a new role for the carbohydrate-binding protein galectin-3 in stabilizing mucosal barriers through its interaction with mucins on the apical glycocalyx. Using the surface of the eye as a model system, we found that galectin-3 colocalized with two distinct membrane-associated mucins, MUC1 and MUC16, on the apical surface of epithelial cells and that both mucins bound to galectin-3 affinity columns in a galactose-dependent manner. Abrogation of the mucin-galectin interaction in four different mucosal epithelial cell types using competitive carbohydrate inhibitors of galectin binding, β-lactose and modified citrus pectin, resulted in decreased levels of galectin-3 on the cell surface with concomitant loss of barrier function, as indicated by increased permeability to rose bengal diagnostic dye. Similarly, down-regulation of mucin O-glycosylation using a stable tetracycline-inducible RNA interfering system to knockdown c1galt1 (T-synthase), a critical galactosyltransferase required for the synthesis of core 1 O-glycans, resulted in decreased cell surface O-glycosylation, reduced cell surface galectin-3, and increased epithelial permeability. Taken together, these results suggest that galectin-3 plays a key role in maintaining mucosal barrier function through carbohydrate-dependent interactions with cell surface mucins. PMID:19556244

Polyvalent Display of Biomolecules on Live Cells.

PubMed

Shi, Peng; Zhao, Nan; Lai, Jinping; Coyne, James; Gaddes, Erin R; Wang, Yong

2018-06-04

Surface display of biomolecules on live cells offers new opportunities to treat human diseases and perform basic studies. Existing methods are primarily focused on monovalent functionalization, that is, the display of single biomolecules across the cell surface. Here we show that the surface of live cells can be functionalized to display polyvalent biomolecular structures through two-step reactions under physiological conditions. This polyvalent functionalization enables the cell surface to recognize the microenvironment one order of magnitude more effectively than with monovalent functionalization. Thus, polyvalent display of biomolecules on live cells holds great potential for various biological and biomedical applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Engineering of Surface Functionality onto Polystyrene Microcarriers for the Attachment and Growth of Human Endothelial Cells

NASA Astrophysics Data System (ADS)

Xiong, Gordon M.; Foord, John S.; Griffiths, Jon-Paul; Parker, Emily M.; Moloney, Mark G.; Choong, Cleo

2014-08-01

This work reports the effects of introducing diverse chemical functionalities onto the surface of polystyrene microcarrier beads on their ability to function as injectable cell carriers. Cellular adhesion and proliferation, as well as cellular outgrowths from microcarrier surfaces, using human umbilical vein endothelial cells (HUVECs), were examined in detail. It was observed that initial cell adhesion appeared to be most significantly decreased by hydrophobicity, whilst cell proliferation appeared to be improved in most chemical functional groups over unmodified polystyrene. Overall, our study highlights the importance of surface chemistry in directing the growth and function of human endothelial cells.

Effect of Inhibition of Deoxyribonucleic Acid and Protein Synthesis on the Direction of Cell Wall Growth in Streptococcus faecalis

PubMed Central

Higgins, M. L.; Daneo-Moore, L.; Boothby, D.; Shockman, G. D.

1974-01-01

Selective inhibition of protein synthesis in Streptococcus faecalis (ATCC 9790) was accompanied by a rapid and severe inhibition of cell division and a reduction of enlargement of cellular surface area. Continued synthesis of cell wall polymers resulted in rapid thickening of the wall to an extent not seen in exponential-phase populations. Thus, the normal direction of wall growth was changed from a preferential feeding out of new wall surface to that of thickening existing cell surfaces. However, the overall manner in which the wall thickened, from nascent septa toward polar regions, was the same in both exponential-phase and inhibited populations. In contrast, selective inhibition of deoxyribonucleic acid (DNA) synthesis using mitomycin C was accompanied by an increase in cellular surface area and by division of about 80% of the cells in random populations. Little or no wall thickening was observed until the synthesis of macromolecules other than DNA was impaired and further cell division ceased. Concomitant inhibition of both DNA and protein synthesis inhibited cell division but permitted an increase in average cell volume. In such doubly inhibited cells, walls thickened less than in cells inhibited for protein synthesis only. On the basis of the results obtained, a model for cell surface enlargement and cell division is presented. The model proposes that: (i) each wall enlargement site is influenced by an individual chromosome replication cycle; (ii) during chromosome replication peripheral surface enlargement would be favored over thickening (or septation); (iii) a signal associated with chromosome termination would favor thickening (and septation) at the expense of surface enlargement; and (iv) a factor or signal related to protein synthesis would be required for one or more of the near terminal stages of cell division or cell separation, or both. Images PMID:4133352

Femtosecond laser-induced microstructures on Ti substrates for reduced cell adhesion

NASA Astrophysics Data System (ADS)

Heitz, J.; Plamadeala, C.; Muck, M.; Armbruster, O.; Baumgartner, W.; Weth, A.; Steinwender, C.; Blessberger, H.; Kellermair, J.; Kirner, S. V.; Krüger, J.; Bonse, J.; Guntner, A. S.; Hassel, A. W.

2017-12-01

Miniaturized pacemakers with a surface consisting of a Ti alloy may have to be removed after several years from their implantation site in the heart and shall, therefore, not be completely overgrown by cells or tissue. A method to avoid this may be to create at the surface by laser-ablation self-organized sharp conical spikes, which provide too little surface for cells (i.e., fibroblasts) to grow on. For this purpose, Ti-alloy substrates were irradiated in the air by 790 nm Ti:sapphire femtosecond laser pulses at fluences above the ablation threshold. The laser irradiation resulted in pronounced microstructure formation with hierarchical surface morphologies. Murine fibroblasts were seeded onto the laser-patterned surface and the coverage by cells was evaluated after 3-21 days of cultivation by means of scanning electron microscopy. Compared to flat surfaces, the cell density on the microstructures was significantly lower, the coverage was incomplete, and the cells had a clearly different morphology. The best results regarding suppression of cell growth were obtained on spike structures which were additionally electrochemically oxidized under acidic conditions. Cell cultivation with additional shear stress could reduce further the number of adherent cells.

Quantifying the pattern of microbial cell dispersion, density and clustering on surfaces of differing chemistries and topographies using multifractal analysis.

PubMed

Wickens, David; Lynch, Stephen; West, Glen; Kelly, Peter; Verran, Joanna; Whitehead, Kathryn A

2014-09-01

The effects of surface topography on bacterial distribution across a surface are of extreme importance when designing novel, hygienic or antimicrobial surface coatings. The majority of methods that are deployed to describe the pattern of cell dispersion, density and clustering across surfaces are currently qualitative. This paper presents a novel application of multifractal analysis to quantitatively measure these factors using medically relevant microorganisms (Staphylococcus aureus or Staphylococcus epidermidis). Surfaces (medical grade 316 stainless steel) and coatings (Ti-ZrN, Ti-ZrN/6.0%Ag, Ti-ZrN/15.6%Ag, TiZrN/24.7%Ag) were used in microbiological retention assays. Results demonstrated that S. aureus displayed a more heterogeneous cell dispersion (∆αAS<1) whilst the dispersion of S. epidermidis was more symmetric and homogeneous (∆αAS≥1). Further, although the surface topography and chemistry had an effect on cell dispersion, density and clustering, the type of bonding that occurred at the surface interface was also important. Both types of cells were influenced by both surface topographical and chemical effects; however, S. aureus was influenced marginally more by surface chemistry whilst S. epidermidis cells was influenced marginally more by surface topography. Thus, this effect was bacterially species specific. The results demonstrate that multifractal analysis is a method that can be used to quantitatively analyse the cell dispersion, density and clustering of retained microorganisms on surfaces. Using quantitative descriptors has the potential to aid the understanding the effect of surface properties on the production of hygienic and antimicrobial coatings. Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical Reactive Anchoring Lipids with Different Performance for Cell Surface Re-engineering Application

PubMed Central

2018-01-01

Introduction of selectively chemical reactive groups at the cell surface enables site-specific cell surface labeling and modification opportunity, thus facilitating the capability to study the cell surface molecular structure and function and the molecular mechanism it underlies. Further, it offers the opportunity to change or improve a cell’s functionality for interest of choice. In this study, two chemical reactive anchor lipids, phosphatidylethanolamine–poly(ethylene glycol)–dibenzocyclooctyne (DSPE–PEG2000–DBCO) and cholesterol–PEG–dibenzocyclooctyne (CHOL–PEG2000–DBCO) were synthesized and their potential application for cell surface re-engineering via lipid fusion were assessed with RAW 264.7 cells as a model cell. Briefly, RAW 264.7 cells were incubated with anchor lipids under various concentrations and at different incubation times. The successful incorporation of the chemical reactive anchor lipids was confirmed by biotinylation via copper-free click chemistry, followed by streptavidin-fluorescein isothiocyanate binding. In comparison, the cholesterol-based anchor lipid afforded a higher cell membrane incorporation efficiency with less internalization than the phospholipid-based anchor lipid. Low cytotoxicity of both anchor lipids upon incorporation into the RAW 264.7 cells was observed. Further, the cell membrane residence time of the cholesterol-based anchor lipid was evaluated with confocal microscopy. This study suggests the potential cell surface re-engineering applications of the chemical reactive anchor lipids. PMID:29503972

The influence of surface integrin binding patterns on specific biomaterial-cell interactions

NASA Astrophysics Data System (ADS)

Beranek, Maggi Marie

As the future of biomaterials progresses toward bioactivity, the biomaterial surface must control non-specific protein adsorption and encourage selective protein and cell adsorption. Integrins alphavbeta3, alpha 1beta1, alpha5beta1 and alpha Mbeta2 are expressed on cells involved in endothelialization, inflammation, and intimal hyperplasia. These cellular events play a vital role in biomaterial biocompatibility, especially in the vascular environment. The overall hypothesis of these studies is that biomaterial surfaces exhibit selective integrin binding, which then specifies differential cell binding. To test this hypothesis, four specific aims were developed. The first aim was designed to determine whether metal and polymeric biomaterials exhibit selective integrin binding. The tested materials included 316L stainless steel, nitinol, gold, Elgiloy RTM, poly(D, L-lactide-co-glycolide), polycarbonate urethane and expanded polytetrafluoroethylene. Discrete integrin binding patterns were detected microscopically using integrin specific fluorescent antibodies. Stainless steel exhibited high level integrin alpha1beta 1 and low level integrin alphaMbeta2 binding pattern. This suggests that this metal surface should selectively encourage endothelial cell to inflammatory cell binding. In contrast, gold bound ten times the amount of integrin alphaMbeta2 compared to integrin alpha1beta1, which should encourage inflammatory cell adhesion. The 65/35 poly(D, L-lactide-co-glycolide) was the only polymeric biomaterial tested that had integrin binding levels comparable to metal biomaterials. Based on these observations, a combinational biomaterial with a surface pattern of 65/35 poly(D, L-lactide-co-glycolide) dots on a 316L stainless steel background was created. A pattern of high level integrin alpha1beta1 binding and low level integrin alpha Mbeta2 binding on this combinational surface indicates that this surface should selectively favor endothelial cell binding. In the second aim, the response of surface-bound integrins to flow-related shear stress was examined. Based on fluorescent analysis, total alphavbeta 3, alpha1beta1, and alpha5beta 1 appeared to increase on stainless steel after 90-minute low shear stress exposure, whereas only alpha5beta1 appeared to increase when exposed to high shear. 65/35 poly(D, L-lactide-co-glycolide) exhibited increased total binding of alpha5beta1 and alphaMbeta2, when exposed to either shear stress level. Exposure to either shear stress regimen appeared to increase binding of all integrins on the combinational surface. These responses to shear stress suggest differential integrin binding affinity compared to stainless steel. Using antibodies specific to the integrin subunits, the apparent increase in surface-bound integrins was found to be related to a surface disassociation of alpha and beta subunits. The third aim evaluated human aortic endothelial cells and acute monocytic leukemia cells (THP-1) cell binding to the tested biomaterial surfaces under both static and flow conditions. Both stainless steel and the combinational surface had increased endothelial cell binding compared to monocyte attachment. Pre-incubation of the surface with the specific integrins significantly inhibited human aortic endothelial cell binding. Aim four was designed to investigate the influence of surface bound integrins on human aortic endothelial cell migration under shear stress. If biomaterial surface integrin binding patterns are specific, then pre-bound surface integrins should competitively inhibit binding of cellular integrins to the surface. Cell migration distance on to alphavbeta3, alpha 1beta1, and alpha5beta1 pre-incubated stainless steel was decreased ten-fold, and decreased by three-fold on both 65/35 poly(D, L-lactide-coglycolide) and combinational surfaces compared to the respective bare surfaces. In contrast, migration distance on to alphaMbeta2 pre-coated stainless steel and combinational surface was decreased by only sixty percent and only fifty percent on alphaMbeta2 precoated 65/35 poly(D, L -lactide-co-glycolide). These results suggested that surface binding sites are selective and critical in governing endothelial cell migration. In conclusion, these results support the hypothesis that a surface that encourages specific integrin binding would promote differential cell binding. The novel integrin binding model used in this investigation may be a methodology that can be employed to evaluate potential vascular biomaterials.

Concise Review: Cell Surface N-Linked Glycoproteins as Potential Stem Cell Markers and Drug Targets.

PubMed

Boheler, Kenneth R; Gundry, Rebekah L

2017-01-01

Stem cells and their derivatives hold great promise to advance regenerative medicine. Critical to the progression of this field is the identification and utilization of antibody-accessible cell-surface proteins for immunophenotyping and cell sorting-techniques essential for assessment and isolation of defined cell populations with known functional and therapeutic properties. Beyond their utility for cell identification and selection, cell-surface proteins are also major targets for pharmacological intervention. Although comprehensive cell-surface protein maps are highly valuable, they have been difficult to define until recently. In this review, we discuss the application of a contemporary targeted chemoproteomic-based technique for defining the cell-surface proteomes of stem and progenitor cells. In applying this approach to pluripotent stem cells (PSCs), these studies have improved the biological understanding of these cells, led to the enhanced use and development of antibodies suitable for immunophenotyping and sorting, and contributed to the repurposing of existing drugs without the need for high-throughput screening. The utility of this latter approach was first demonstrated with human PSCs (hPSCs) through the identification of small molecules that are selectively toxic to hPSCs and have the potential for eliminating confounding and tumorigenic cells in hPSC-derived progeny destined for research and transplantation. Overall, the cutting-edge technologies reviewed here will accelerate the development of novel cell-surface protein targets for immunophenotyping, new reagents to improve the isolation of therapeutically qualified cells, and pharmacological studies to advance the treatment of intractable diseases amenable to cell-replacement therapies. Stem Cells Translational Medicine 2017;6:131-138. © 2016 The Authors Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Surface Proteins of Gram-Positive Bacteria and Mechanisms of Their Targeting to the Cell Wall Envelope

PubMed Central

Navarre, William Wiley; Schneewind, Olaf

1999-01-01

The cell wall envelope of gram-positive bacteria is a macromolecular, exoskeletal organelle that is assembled and turned over at designated sites. The cell wall also functions as a surface organelle that allows gram-positive pathogens to interact with their environment, in particular the tissues of the infected host. All of these functions require that surface proteins and enzymes be properly targeted to the cell wall envelope. Two basic mechanisms, cell wall sorting and targeting, have been identified. Cell well sorting is the covalent attachment of surface proteins to the peptidoglycan via a C-terminal sorting signal that contains a consensus LPXTG sequence. More than 100 proteins that possess cell wall-sorting signals, including the M proteins of Streptococcus pyogenes, protein A of Staphylococcus aureus, and several internalins of Listeria monocytogenes, have been identified. Cell wall targeting involves the noncovalent attachment of proteins to the cell surface via specialized binding domains. Several of these wall-binding domains appear to interact with secondary wall polymers that are associated with the peptidoglycan, for example teichoic acids and polysaccharides. Proteins that are targeted to the cell surface include muralytic enzymes such as autolysins, lysostaphin, and phage lytic enzymes. Other examples for targeted proteins are the surface S-layer proteins of bacilli and clostridia, as well as virulence factors required for the pathogenesis of L. monocytogenes (internalin B) and Streptococcus pneumoniae (PspA) infections. In this review we describe the mechanisms for both sorting and targeting of proteins to the envelope of gram-positive bacteria and review the functions of known surface proteins. PMID:10066836

In situ immobilization of proteins and RGD peptide on polyurethane surfaces via poly(ethylene oxide) coupling polymers for human endothelial cell growth.

PubMed

Wang, Dong-an; Ji, Jian; Sun, Yong-hong; Shen, Jia-cong; Feng, Lin-xian; Elisseeff, Jennifer H

2002-01-01

A "CBABC"-type pentablock coupling polymer, mesylMPEO, was designed and synthesized to promote human endothelial cell growth on the surfaces of polyurethane biomaterials. The polymer was composed of a central 4,4'-methylenediphenyl diisocyanate (MDI) coupling unit and poly(ethylene oxide) (PEO) spacer arms with methanesulfonyl (mesyl) end groups pendent on both ends. As the presurface modifying additive (pre-SMA), the mesylMPEO was noncovalently introduced onto the poly(ether urethane) (PEU) surfaces by dip coating, upon which the protein/peptide factors (gelatin, albumin, and arginine-glycine-aspartic acid tripeptide [RGD]) were covalently immobilized in situ by cleavage of the original mesyl end groups. The pre-SMA synthesis and PEU surface modification were characterized using nuclear magnetic resonance spectroscopy ((1)H NMR), attenuated total reflection infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). Human umbilical vein endothelial cells (HUVEC) were harvested manually by collagenase digestion and seeded on the modified PEU surfaces. Cell adhesion ratios (CAR) and cell proliferation ratios (CPR) were measured using flow cytometry, and the individual cell viability (ICV) was determined by MTT assay. The cell morphologies were investigated by optical inverted microscopy (OIM) and scanning electrical microscopy (SEM). The gelatin- and RGD-modified surfaces were HUVEC-compatible and promoted HUVEC growth. The albumin-modified surfaces were compatible but inhibited cell adhesion. The results also indicated that, for HUVEC in vitro cultivation, the cell adhesion stage was of particular importance and had a significant impact on the cell responses to the modified surfaces.

Ion-implanted polytetrafluoroethylene enhances Saccharomyces cerevisiae biofilm formation for improved immobilization

PubMed Central

Tran, Clara T. H.; Kondyurin, Alexey; Hirsh, Stacey L.; McKenzie, David R.; Bilek, Marcela M. M.

2012-01-01

The surface of polytetrafluoroethylene (PTFE) was modified using plasma immersion ion implantation (PIII) with the aim of improving its ability to immobilize yeast. The density of immobilized cells on PIII-treated and -untreated PTFE was compared as a function of incubation time over 24 h. Rehydrated yeast cells attached to the PIII-treated PTFE surface more rapidly, with higher density, and greater attachment strength than on the untreated surface. The immobilized yeast cells were removed mechanically or chemically with sodium hydroxide and the residues left on the surfaces were analysed with Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). The results revealed that the mechanism of cell attachment on both surfaces differs and a model is presented for each. Rapid attachment on the PIII-treated surface occurs through covalent bonds of cell wall proteins and the radicals on the treated surface. In contrast, on the untreated surface, only physisorbed molecules were found in the residue and lipids were more highly concentrated than proteins. The presence of lipids in the residue was found to be a consequence of damage to the plasma membrane during the rehydration process and the increased cell stress was also apparent by the amount of Hsp12 in the protein residue. The immobilized yeast cells on PIII-treated PTFE were found to be as active as yeast cells in suspension. PMID:22696486

Cell-Adhesive and Cell-Repulsive Zwitterionic Oligopeptides for Micropatterning and Rapid Electrochemical Detachment of Cells

PubMed Central

Kakegawa, Takahiro; Mochizuki, Naoto; Sadr, Nasser; Suzuki, Hiroaki

2013-01-01

In this study, we describe the development of oligopeptide-modified cell culture surfaces from which adherent cells can be rapidly detached by application of an electrical stimulus. An oligopeptide, CGGGKEKEKEK, was designed with a terminal cysteine residue to mediate binding to a gold surface via a gold–thiolate bond. The peptide forms a self-assembled monolayer through the electrostatic force between the sequence of alternating charged glutamic acid (E) and lysine (K) residues. The dense and electrically neutral oligopeptide zwitterionic layer of the modified surface was resistant to nonspecific adsorption of proteins and adhesion of cells, while the surface was altered to cell adhesive by the addition of a second oligopeptide (CGGGKEKEKEKGRGDSP) containing the RGD cell adhesion motif. Application of a negative electrical potential to this gold surface cleaved the gold–thiolate bond, leading to desorption of the oligopeptide layer, and rapid (within 2 min) detachment of virtually all cells. This approach was applicable not only to detachment of cell sheets but also for transfer of cell micropatterns to a hydrogel. This electrochemical approach of cell detachment may be a useful tool for tissue-engineering applications. PMID:22853640

Surface deformation during an action potential in pearled cells

NASA Astrophysics Data System (ADS)

Mussel, Matan; Fillafer, Christian; Ben-Porath, Gal; Schneider, Matthias F.

2017-11-01

Electric pulses in biological cells (action potentials) have been reported to be accompanied by a propagating cell-surface deformation with a nanoscale amplitude. Typically, this cell surface is covered by external layers of polymer material (extracellular matrix, cell wall material, etc.). It was recently demonstrated in excitable plant cells (Chara braunii) that the rigid external layer (cell wall) hinders the underlying deformation. When the cell membrane was separated from the cell wall by osmosis, a mechanical deformation, in the micrometer range, was observed upon excitation of the cell. The underlying mechanism of this mechanical pulse has, to date, remained elusive. Herein we report that Chara cells can undergo a pearling instability, and when the pearled fragments were excited even larger and more regular cell shape changes were observed (˜10 -100 μ m in amplitude). These transient cellular deformations were captured by a curvature model that is based on three parameters: surface tension, bending rigidity, and pressure difference across the surface. In this paper these parameters are extracted by curve-fitting to the experimental cellular shapes at rest and during excitation. This is a necessary step to identify the mechanical parameters that change during an action potential.

Influence of non-adherent yeast cells on electrical characteristics of diamond-based field-effect transistors

NASA Astrophysics Data System (ADS)

Procházka, Václav; Cifra, Michal; Kulha, Pavel; Ižák, Tibor; Rezek, Bohuslav; Kromka, Alexander

2017-02-01

Diamond thin films provide unique features as substrates for cell cultures and as bio-electronic sensors. Here we employ solution-gated field effect transistors (SGFET) based on nanocrystalline diamond thin films with H-terminated surface which exhibits the sub-surface p-type conductive channel. We study an influence of yeast cells (Saccharomyces cerevisiae) on electrical characteristics of the diamond SGFETs. Two different cell culture solutions (sucrose and yeast peptone dextrose-YPD) are used, with and without the cells. We have found that transfer characteristics of the SGFETs exhibit a negative shift of the gate voltage by -26 mV and -42 mV for sucrose and YPD with cells in comparison to blank solutions without the cells. This effect is attributed to a local pH change in close vicinity of the H-terminated diamond surface due to metabolic processes of the yeast cells. The pH sensitivity of the diamond-based SGFETs, the role of cell and protein adhesion on the gate surface and the role of negative surface charge of yeast cells on the SGFETs electrical characteristics are discussed as well.

Cytoskeletal changes in actin and microtubules underlie the developing surface mechanical properties of sensory and supporting cells in the mouse cochlea

PubMed Central

Szarama, Katherine B.; Gavara, Núria; Petralia, Ronald S.; Kelley, Matthew W.; Chadwick, Richard S.

2012-01-01

Correct patterning of the inner ear sensory epithelium is essential for the conversion of sound waves into auditory stimuli. Although much is known about the impact of the developing cytoskeleton on cellular growth and cell shape, considerably less is known about the role of cytoskeletal structures on cell surface mechanical properties. In this study, atomic force microscopy (AFM) was combined with fluorescence imaging to show that developing inner ear hair cells and supporting cells have different cell surface mechanical properties with different developmental time courses. We also explored the cytoskeletal organization of developing sensory and non-sensory cells, and used pharmacological modulation of cytoskeletal elements to show that the developmental increase of hair cell stiffness is a direct result of actin filaments, whereas the development of supporting cell surface mechanical properties depends on the extent of microtubule acetylation. Finally, this study found that the fibroblast growth factor signaling pathway is necessary for the developmental time course of cell surface mechanical properties, in part owing to the effects on microtubule structure. PMID:22573615

Surface grafting of a thermoplastic polyurethane with methacrylic acid by previous plasma surface activation and by ultraviolet irradiation to reduce cell adhesion.

PubMed

Alves, P; Pinto, S; Kaiser, Jean-Pierre; Bruinink, Arie; de Sousa, Hermínio C; Gil, M H

2011-02-01

The material performance, in a biological environment, is mainly mediated by its surface properties and by the combination of chemical, physical, biological, and mechanical properties required, for a specific application. In this study, the surface of a thermoplastic polyurethane (TPU) material (Elastollan(®)1180A50) was activated either by plasma or by ultra-violet (UV) irradiation. After surface activation, methacrylic acid (MAA) was linked to the surface of TPU in order to improve its reactivity and to reduce cell adhesion. Grafted surfaces were evaluated by X-ray photoelectron spectroscopy (XPS), by atomic force microscopy (AFM) and by contact angle measurements. Blood compatibility studies and cell adhesion tests with human bone marrow cells (HBMC) were also performed. If was found that UV grafting method led to better results than the plasma activation method, since cell adhesion was reduced when methacrylic acid was grafted to the TPU surface by UV. Copyright © 2010 Elsevier B.V. All rights reserved.

Adjustment of surface chemical and physical properties with functionalized polymers to control cell adhesion

NASA Astrophysics Data System (ADS)

Zhou, Zhaoli

Cell-surface interaction is crucial in many cellular functions such as movement, growth, differentiation, proliferation and survival. In the present work, we have developed several strategies to design and prepare synthetic polymeric materials with selected cues to control cell attachment. To promote neuronal cell adhesion on the surfaces, biocompatible, non-adhesive PEG-based materials were modified with neurotransmitter acetylcholine functionalities to produce hydrogels with a range of porous structures, swollen states, and mechanical strengths. Mice hippocampal cells cultured on the hydrogels showed differences in number, length of processes and exhibited different survival rates, thereby highlighting the importance of chemical composition and structure in biomaterials. Similar strategies were used to prepare polymer brushes to assess how topographical cues influence neuronal cell behaviors. The brushes were prepared using the "grown from" method through surface-initiated atom transfer radical polymerization (SI-ATRP) reactions and further patterned via UV photolithography. Protein absorption tests and hippocampal neuronal cell culture of the brush patterns showed that both protein and neuronal cells can adhere to the patterns and therefore can be guided by the patterns at certain length scales. We also prepared functional polymers to discourage attachment of undesirable cells on the surfaces. For example, we synthesized PEG-perfluorinated alkyl amphiphilic surfactants to modify polystyrene-block-poly(ethylene-ran-butylene)- block-polyisoprene (SEBI or K3) triblock copolymers for marine antifouling/fouling release surface coatings. Initial results showed that the polymer coated surfaces can facilitate removal of Ulva sporelings on the surfaces. In addition, we prepared both bioactive and dual functional biopassive/bioactive antimicrobial coatings based on SEBI polymers. Incubating the polymer coated surfaces with gram-positive bacteria (S. aureus), gram-negative bacteria (E. coli) and marine bacteria (C. marina ) species demonstrated that, unlike biopassive surfaces, the dual functionality polymer coated surfaces can significantly reduce both live and dead cells, without killing the cells in the culture media. The knowledge gained from those studies offers opportunities for further modification and potential applications of those types of polymers in the future.

Rear surface effects in high efficiency silicon solar cells

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

Wenham, S.R.; Robinson, S.J.; Dai, X.

1994-12-31

Rear surface effects in PERL solar cells can lead not only to degradation in the short circuit current and open circuit voltage, but also fill factor. Three mechanisms capable of changing the effective rear surface recombination velocity with injection level are identified, two associated with oxidized p-type surfaces, and the third with two dimensional effects associated with a rear floating junction. Each of these will degrade the fill factor if the range of junction biases corresponding to the rear surface transition, coincides with the maximum power point. Despite the identified non idealities, PERL cells with rear floating junctions (PERF cells)more » have achieved record open circuit voltages for silicon solar cells, while simultaneously achieving fill factor improvements relative to standard PERL solar cells. Without optimization, a record efficiency of 22% has been demonstrated for a cell with a rear floating junction. The results of both theoretical and experimental studies are provided.« less

Constrained ceramic-filled polymer armor

DOEpatents

Sandstrom, D.J.; Calkins, N.C.; Gac, F.D.

1990-11-13

An armor system is disclosed in which a plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material, which is a ceramic material in particulate form dispersed in a polymeric matrix. 5 figs.

Characterization of atrial natriuretic peptide degradation by cell-surface peptidase activity on endothelial cells

NASA Technical Reports Server (NTRS)

Frost, S. J.; Whitson, P. A.

1993-01-01

Atrial natriuretic peptide (ANP) is a fluid-regulating peptide hormone that promotes vasorelaxation, natriuresis, and diuresis. The mechanisms for the release of ANP and for its clearance from the circulation play important roles in modulating its biological effects. Recently, we have reported that the cell surface of an endothelial cell line, CPA47, could degrade 125I-ANP in the presence of EDTA. In this study, we have characterized this degradation of 125I-ANP. The kinetics of ANP degradation by the surface of CPA47 cells were first order, with a Km of 320 +/- 60 nM and Vmax of 35 +/- 14 pmol of ANP degraded/10 min/10(5) cells at pH 7.4. ANP is degraded by the surface of CPA47 cells over a broad pH range from 7.0-8.5. Potato carboxypeptidase inhibitor and bestatin inhibited 125I-ANP degradation, suggesting that this degradative activity on the surface of CPA47 cells has exopeptidase characteristics. The selectivity of CPA47 cell-surface degradation of ANP was demonstrated when 125I-ANP degradation was inhibited in the presence of neuropeptide Y and angiotensin I and II but not bradykinin, bombesin, endothelin-1, or substance P. The C-terminal amino acids phe26 and tyr28 were deduced to be important for ANP interaction with the cell-surface peptidase(s) based on comparison of the IC50 of various ANP analogues and other natriuretic peptides for the inhibition of ANP degradation. These data suggest that a newly characterized divalent cation-independent exopeptidase(s) that selectively recognizes ANP and some other vasoactive peptides exists on the surface of endothelial cells.

Polymer surface functionalities that control human embryoid body cell adhesion revealed by high throughput surface characterization of combinatorial material microarrays

PubMed Central

Yang, Jing; Mei, Ying; Hook, Andrew L.; Taylor, Michael; Urquhart, Andrew J.; Bogatyrev, Said R.; Langer, Robert; Anderson, Daniel G.; Davies, Martyn C.; Alexander, Morgan R.

2010-01-01

High throughput materials discovery using combinatorial polymer microarrays to screen for new biomaterials with new and improved function is established as a powerful strategy. Here we combine this screening approach with high throughput surface characterisation (HT-SC) to identify surface structure-function relationships. We explore how this combination can help to identify surface chemical moieties that control protein adsorption and subsequent cellular response. The adhesion of human embryoid body (hEB) cells to a large number (496) of different acrylate polymers synthesized in a microarray format is screened using a high throughput procedure. To determine the role of the polymer surface properties on hEB cell adhesion, detailed HT-SC of these acrylate polymers is carried out using time of flight secondary ion mass spectrometry (ToF SIMS), x-ray photoelectron spectroscopy (XPS), pico litre drop sessile water contact angle (WCA) measurement and atomic force microscopy (AFM). A structure-function relationship is identified between the ToF SIMS analysis of the surface chemistry after a fibronectin (Fn) pre-conditioning step and the cell adhesion to each spot using the multivariate analysis technique partial least squares (PLS) regression. Secondary ions indicative of the adsorbed Fn correlate with increased cell adhesion whereas glycol and other functionalities from the polymers are identified that reduce cell adhesion. Furthermore, a strong relationship between the ToF SIMS spectra of bare polymers and the cell adhesion to each spot is identified using PLS regression. This identifies a role for both the surface chemistry of the bare polymer and the pre-adsorbed Fn, as-represented in the ToF SIMS spectra, in controlling cellular adhesion. In contrast, no relationship is found between cell adhesion and wettability, surface roughness, elemental or functional surface composition. The correlation between ToF SIMS data of the surfaces and the cell adhesion demonstrates the ability of identifying surface moieties that control protein adsorption and subsequent cell adhesion using ToF SIMS and multivariate analysis. PMID:20832108

Multi-scale cell/surface interaction on modified titanium aluminum vanadium surfaces

NASA Astrophysics Data System (ADS)

Chen, Jianbo

This dissertation presents a series of experimental studies of the effects of multi-scale cell/surface interactions on modified Ti-6Al-4V surfaces. These include laser-grooved surfaces; porous structures and RGD-coated laser-grooved surfaces. A nano-second DPSS UV lasers with a Gaussian pulse energy profile was used to introduce the desired micro-groove geometries onto Ti-6Al-4V surfaces. This was done without inducing micro-cracks or significant changes in surface chemistry within the heat affected zones. The desired 8-12 mum groove depths and widths were achieved by the control of pulse frequency, scan speed, and the lens focal length that controls spot size. The interactions between human osteosarcoma (HOS) cells and laser-grooved Ti-6Al-4V surfaces were investigated after 48 hours of cell culture. The cell behavior, including cell spreading, alignment and adhesion, was elucidated using scanning electronic microscopy (SEM), immuno-fluorescence staining and enzymatic detachment. Contact guidance was shown to increase as grooved spacing decreased. For the range of micro-groove geometries studied, micro-grooves with groove spacings of 20 mum provided the best combination of cell orientation and adhesion. Short-term adhesion experiments (15 mins to 1 day) also revealed that there is a positive correlation between cell orientation and cell adhesion. Contact guidance on the micro-grooved surfaces is shown to be enhanced by nano- and micro-scale asperities that provide sites for the attachment of lamellopodia during cell locomotion and spreading. Contact guidance is also promoted by the geometrical confinement provided by laser grooves. An experimental study of initial cell spreading and ingrowth into Ti-6Al-4V porous structures was also carried out on porous structures with different pore sizes and geometries. A combination of SEM, the tetrazolium salt (MTT) colorimetric assay and enzymatic detachment were used to study cell spreading and adhesion. The extent of cell ingrowth, pore coverage, cell adhesion and proliferation was observed to increase with decreasing pore size. It was found that fiber geometries provided guidance for cell spreading along the fiber directions. However, the larger gaps in fiber geometries made pore bridging difficult. Finally, this dissertation presents an in vivo study of the combined effects of laser microgrooving and RGD-coating on the osseointegration of implanted Ti-6Al-4V pins. Both histological and biomechanical results show that the combination of laser microgrooving and RGD-coating results in improved osseointegration over the control surfaces. All the above findings have important implications for future orthopedic and dental implant design.

β-Arrestin1 and Distinct CXCR4 Structures Are Required for Stromal Derived Factor-1 to Downregulate CXCR4 Cell-Surface Levels in Neuroblastoma

PubMed Central

Clift, Ian C.; Bamidele, Adebowale O.; Rodriguez-Ramirez, Christie; Kremer, Kimberly N.

2014-01-01

CXC chemokine receptor 4 (CXCR4) is a G protein–coupled receptor (GPCR) located on the cell surface that signals upon binding the chemokine stromal derived factor-1 (SDF-1; also called CXCL 12). CXCR4 promotes neuroblastoma proliferation and chemotaxis. CXCR4 expression negatively correlates with prognosis and drives neuroblastoma growth and metastasis in mouse models. All functions of CXCR4 require its expression on the cell surface, yet the molecular mechanisms that regulate CXCR4 cell-surface levels in neuroblastoma are poorly understood. We characterized CXCR4 cell-surface regulation in the related SH-SY5Y and SK-N-SH human neuroblastoma cell lines. SDF-1 treatment caused rapid down-modulation of CXCR4 in SH-SY5Y cells. Pharmacologic activation of protein kinase C similarly reduced CXCR4, but via a distinct mechanism. Analysis of CXCR4 mutants delineated two CXCR4 regions required for SDF-1 treatment to decrease cell-surface CXCR4 in neuroblastoma cells: the isoleucine-leucine motif at residues 328 and 329 and residues 343–352. In contrast, and unlike CXCR4 regulation in other cell types, serines 324, 325, 338, and 339 were not required. Arrestin proteins can bind and regulate GPCR cell-surface expression, often functioning together with kinases such as G protein–coupled receptor kinase 2 (GRK2). Using SK-N-SH cells which are naturally deficient in β-arrestin1, we showed that β-arrestin1 is required for the CXCR4 343–352 region to modulate CXCR4 cell-surface expression following treatment with SDF-1. Moreover, GRK2 overexpression enhanced CXCR4 internalization, via a mechanism requiring both β-arrestin1 expression and the 343–352 region. Together, these results characterize CXCR4 structural domains and β-arrestin1 as critical regulators of CXCR4 cell-surface expression in neuroblastoma. β-Arrestin1 levels may therefore influence the CXCR4-driven metastasis of neuroblastoma as well as prognosis. PMID:24452472

Biocompatible, smooth, plasma-treated nickel-titanium surface--an adequate platform for cell growth.

PubMed

Chrzanowski, W; Szade, J; Hart, A D; Knowles, J C; Dalby, M J

2012-02-01

High nickel content is believed to reduce the number of biomedical applications of nickel-titanium alloy due to the reported toxicity of nickel. The reduction in nickel release and minimized exposure of the cell to nickel can optimize the biocompatibility of the alloy and increase its use in the application where its shape memory effects and pseudoelasticity are particularly useful, e.g., spinal implants. Many treatments have been tried to improve the biocompatibility of Ni-Ti, and results suggest that a native, smooth surface could provide sufficient tolerance, biologically. We hypothesized that the native surface of nickel-titanium supports cell differentiation and insures good biocompatibility. Three types of surface modifications were investigated: thermal oxidation, alkali treatment, and plasma sputtering, and compared with smooth, ground surface. Thermal oxidation caused a drop in surface nickel content, while negligible chemistry changes were observed for plasma-modified samples when compared with control ground samples. In contrast, alkali treatment caused significant increase in surface nickel concentration and accelerated nickel release. Nickel release was also accelerated in thermally oxidized samples at 600 °C, while in other samples it remained at low level. Both thermal oxidation and alkali treatment increased the roughness of the surface, but mean roughness R(a) was significantly greater for the alkali-treated ones. Ground and plasma-modified samples had 'smooth' surfaces with R(a)=4 nm. Deformability tests showed that the adhesion of the surface layers on samples oxidized at 600 °C and alkali treatment samples was not sufficient; the layer delaminated upon deformation. It was observed that the cell cytoskeletons on the samples with a high nickel content or release were less developed, suggesting some negative effects of nickel on cell growth. These effects were observed primarily during initial cell contact with the surface. The most favorable cell responses were observed for ground and plasma-sputtered surfaces. These studies indicated that smooth, plasma-modified surfaces provide sufficient properties for cells to grow. © The Author(s), 2011.

Patterns of surface burrow plugging in a colony of black-tailed prairie dogs occupied by black-footed ferrets

USGS Publications Warehouse

Eads, David E.; Biggins, Dean E.

2012-01-01

Black-tailed prairie dogs (Cynomys ludovicianus) can surface-plug openings to a burrow occupied by a black-footed ferret (Mustela nigripes). At a coarse scale, surface plugs are more common in colonies of prairie dogs occupied by ferrets than in colonies without ferrets. However, little is known about spatial and temporal patterns of surface plugging in a colony occupied by ferrets. In a 452-ha colony of black-tailed prairie dogs in South Dakota, we sampled burrow openings for surface plugs and related those data to locations of ferrets observed during spotlight surveys. Of 67,574 burrow openings in the colony between June and September 2007, 3.7% were plugged. In a colony-wide grid of 80 m × 80 m cells, the occurrence of surface plugging (≥1 opening plugged) was greater in cells used by ferrets (93.3% of cells) than in cells not observably used by ferrets (70.6%). Rates of surface plugging (percentages of openings plugged) were significantly higher in cells used by ferrets (median = 3.7%) than in cells without known ferret use (median = 3.2%). Also, numbers of ferret locations in cells correlated positively with numbers of mapped surface plugs in the cells. To investigate surface plugging at finer temporal and spatial scales, we compared rates of surface plugging in 20-m-radius circle-plots centered on ferret locations and in random plots 1–4 days after observing a ferret (Jun–Oct 2007 and 2008). Rates of surface plugging were greater in ferret-plots (median = 12.0%) than in random plots (median = 0%). For prairie dogs and their associates, the implications of surface plugging could be numerous. For instance, ferrets must dig to exit or enter plugged burrows (suggesting energetic costs), and surface plugs might influence microclimates in burrows and consequently influence species that cannot excavate soil (e.g., fleas that transmit the plague bacterium Yersinia pestis).

Various fates of neuronal progenitor cells observed on several different chemical functional groups

NASA Astrophysics Data System (ADS)

Liu, Xi; Wang, Ying; He, Jin; Wang, Xiu-Mei; Cui, Fu-Zhai; Xu, Quan-Yuan

2011-12-01

Neuronal progenitor cells cultured on gold-coated glass surfaces modified by different chemical functional groups, including hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), bromo (-Br), mercapto (-SH), - Phenyl and methyl (-CH3), were studied here to investigate the influence of surface chemistry on the cells' adhesion, morphology, proliferation and functional gene expression. Focal adhesion staining indicated in the initial culture stage cells exhibited morphological changes in response to different chemical functional groups. Cells cultured on -NH2 grafted surface displayed focal adhesion plaque and flattened morphology and had the largest contact area. However, their counter parts on -CH3 grafted surface displayed no focal adhesion and rounded morphology and had the smallest contact area. After 6 days culture, the proliferation trend was as follows: -NH2 > -SH> -COOH> - Phenyl > - Br > -OH> -CH3. To determine the neural functional properties of the cells affected by surface chemistry, the expression of glutamate decarboxylase (GAD67), nerve growth factor (NGF) and brainderived neurotrophic factor (BDNF) were characterized. An increase of GAD67 expression was observed on -NH2, -COOH and -SH grafted surfaces, while no increase in NGF and BDNF expression was observed on any chemical surfaces. These results highlight the importance of surface chemistry in the fate determination of neuronal progenitor cells, and suggest that surface chemistry must be considered in the design of biomaterials for neural tissue engineering.

Development of functional biointerfaces by surface modification of polydimethylsiloxane with bioactive chlorogenic acid.

PubMed

Wu, Ming; He, Jia; Ren, Xiao; Cai, Wen-Sheng; Fang, Yong-Chun; Feng, Xi-Zeng

2014-04-01

The effect of physicochemical surface properties and chemical structure on the attachment and viability of bacteria and mammalian cells has been extensively studied for the development of biologically relevant applications. In this study, we report a new approach that uses chlorogenic acid (CA) to modify the surface wettability, anti-bacterial activity and cell adhesion properties of polydimethylsiloxane (PDMS). The chemical structure of the surface was obtained by X-ray photoelectron spectroscopy (XPS), the roughness was measured by atomic force microscopy (AFM), and the water contact angle was evaluated for PDMS substrates both before and after CA modification. Molecular modelling showed that the modification was predominately driven by van der Waals and electrostatic interactions. The exposed quinic-acid moiety improved the hydrophilicity of CA-modified PDMS substrates. The adhesion and viability of E. coli and HeLa cells were investigated using fluorescence and phase contrast microscopy. Few viable bacterial cells were found on CA-coated PDMS surfaces compared with unmodified PDMS surfaces. Moreover, HeLa cells exhibited enhanced adhesion and increased spreading on the modified PDMS surface. Thus, CA-coated PDMS surfaces reduced the ratio of viable bacterial cells and increased the adhesion of HeLa cells. These results contribute to the purposeful design of anti-bacterial surfaces for medical device use. Copyright © 2013 Elsevier B.V. All rights reserved.

Why the dish makes a difference: quantitative comparison of polystyrene culture surfaces.

PubMed

Zeiger, Adam S; Hinton, Benjamin; Van Vliet, Krystyn J

2013-07-01

There is wide anecdotal recognition that biological cell viability and behavior can vary significantly as a function of the source of commercial tissue culture polystyrene (TCPS) culture vessels to which those cells adhere. However, this marked material dependency is typically resolved by selecting and then consistently using the same manufacturer's product - following protocol - rather than by investigating the material properties that may be responsible for such experimental variation. Here, we quantified several physical properties of TCPS surfaces obtained from a wide range of commercial sources and processing steps, through the use of atomic force microscopy (AFM)-based imaging and analysis, goniometry and protein adsorption quantification. We identify qualitative differences in surface features, as well as quantitative differences in surface roughness and wettability that cannot be attributed solely to differences in surface chemistry. We also find significant differences in cell morphology and proliferation among cells cultured on different TCPS surfaces, and resolve a correlation between nanoscale surface roughness and cell proliferation rate for both cell types considered. Interestingly, AFM images of living adherent cells on these nanotextured surfaces demonstrate direct interactions between cellular protrusions and topographically distinct features. These results illustrate and quantify the significant differences in material surface properties among these ubiquitous materials, allowing us to better understand why the dish can make a difference in biological experiments. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mouse Elberfeld (ME) virus determines the cell surface alterations when mixedly infecting poliovirus-infected cells.

PubMed

Zeichhardt, H; Schlehofer, J R; Wetz, K; Hampl, H; Habermehl, K O

1982-02-01

The surface alterations of HEp-2 cells induced by mixed infection with two different picornaviruses (poliovirus and ME virus) were compared by scanning electron microscopic and transmission electron microscopic studies and by 51Cr-release assay. The contribution of each of the viruses to the resulting surface changes was discernible, as investigations on the chronology of the cytopathic alterations demonstrated that the changes were distinct for either virus. The surface of ME virus-infected cells was characterized by large membranous structures ('sheets' and blebs) representing huge vacuoles. These sheets were not seen in poliovirus-infected cells. Poliovirus induced more prominent cell pycnosis, elongation of filopodia and condensation of collapsed microvilli on the cell surface than ME virus. Mixed infection with these two viruses led to surface alterations typical for ME virus. These ME virus-specific changes occurred irrespective of poliovirus reproduction or its inhibition by guanidine. ME virus-specific alterations also predominated in cytolytic membrane damage as expressed by 51Cr-release from infected cells. 51Cr-release was more pronounced from ME virus than from poliovirus-infected cells, even when ME virus reproduction was suppressed by interfering poliovirus. However, alteration of the internal structures of the infected cells was only dominated by ME virus when the reproduction of poliovirus was suppressed.

Stem cell responses to plasma surface modified electrospun polyurethane scaffolds.

PubMed

Zandén, Carl; Hellström Erkenstam, Nina; Padel, Thomas; Wittgenstein, Julia; Liu, Johan; Kuhn, H Georg

2014-07-01

The topographical effects from functional materials on stem cell behavior are currently of interest in tissue engineering and regenerative medicine. Here we investigate the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell (hESC) and rat postnatal neural stem cell (NSC) responses. The plasma gases were found to induce three combinations of fiber surface functionalities and roughness textures. On randomly oriented fibers, plasma treatments lead to substantially increased hESC attachment and proliferation as compared to native fibers. Argon plasma was found to induce the most optimal combination of surface functionality and roughness for cell expansion. Contact guided migration of cells and alignment of cell processes were observed on aligned fibers. Neuronal differentiation around 5% was found for all samples and was not significantly affected by the induced variations of surface functional group distribution or individual fiber topography. In this study the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell and rat postnatal neural stem cell (NSC) responses is studied with the goal of clarifying the potential effects of functional materials on stem cell behavior, a topic of substantial interest in tissue engineering and regenerative medicine. Copyright © 2014 Elsevier Inc. All rights reserved.

A monoclonal antibody inhibits calcium accumulation and skeleton formation in cultured embryonic cells of the sea urchin.

PubMed

Carson, D D; Farach, M C; Earles, D S; Decker, G L; Lennarz, W J

1985-06-01

The assembly of the spicules (primitive skeleton) of the sea urchin embryo is being studied in primary mesenchyme cells cultured in vitro. A monoclonal antibody (1223) has been prepared that inhibits the deposition of CaCO3 into the spicules. This antibody reacts with a 130,000 Mr cell-surface protein that is concentrated on the surface of approximately 5% of the cells of dissociated gastrula stage embryos. When primary mesenchyme cells in the embryo or cells cultured in vitro are examined, the 1223 antigen is detected on the surface of the cells and on the extracellular material associated with the spicule. We conclude that the 1223 antibody recognizes a cell-surface protein that plays an essential role in spicule formation.

Coupling Binding to Catalysis: Using Yeast Cell Surface Display to Select Enzymatic Activities.

PubMed

Zhang, Keya; Bhuripanyo, Karan; Wang, Yiyang; Yin, Jun

2015-01-01

We find yeast cell surface display can be used to engineer enzymes by selecting the enzyme library for high affinity binding to reaction intermediates. Here we cover key steps of enzyme engineering on the yeast cell surface including library design, construction, and selection based on magnetic and fluorescence-activated cell sorting.

Steric Shielding of Surface Epitopes and Impaired Immune Recognition Induced by the Ebola Virus Glycoprotein

PubMed Central

Francica, Joseph R.; Varela-Rohena, Angel; Medvec, Andrew; Plesa, Gabriela; Riley, James L.; Bates, Paul

2010-01-01

Many viruses alter expression of proteins on the surface of infected cells including molecules important for immune recognition, such as the major histocompatibility complex (MHC) class I and II molecules. Virus-induced downregulation of surface proteins has been observed to occur by a variety of mechanisms including impaired transcription, blocks to synthesis, and increased turnover. Viral infection or transient expression of the Ebola virus (EBOV) glycoprotein (GP) was previously shown to result in loss of staining of various host cell surface proteins including MHC1 and β1 integrin; however, the mechanism responsible for this effect has not been delineated. In the present study we demonstrate that EBOV GP does not decrease surface levels of β1 integrin or MHC1, but rather impedes recognition by steric occlusion of these proteins on the cell surface. Furthermore, steric occlusion also occurs for epitopes on the EBOV glycoprotein itself. The occluded epitopes in host proteins and EBOV GP can be revealed by removal of the surface subunit of GP or by removal of surface N- and O- linked glycans, resulting in increased surface staining by flow cytometry. Importantly, expression of EBOV GP impairs CD8 T-cell recognition of MHC1 on antigen presenting cells. Glycan-mediated steric shielding of host cell surface proteins by EBOV GP represents a novel mechanism for a virus to affect host cell function, thereby escaping immune detection. PMID:20844579

The behavior of MC3T3-E1 cells on chitosan/poly-L-lysine composite films: effect of nanotopography, surface chemistry, and wettability.

PubMed

Zheng, Zhenhuan; Zhang, Ling; Kong, Lijun; Wang, Aijun; Gong, Yandao; Zhang, Xiufang

2009-05-01

In the present work, a series of composite films were produced from chitosan/poly-L-lysine blend solutions. The surface topography, chemistry, and wettability of composite films were characterized by atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and contact angle assay, respectively. For all composite films, blending with poly-L-lysine induced changes in surface chemistry and wettability. Interestingly, it was also found that increasing poly-L-lysine weight fraction in blend solutions could result in different nanoscaled surface topographic features, which displayed particle-, granule-, or fiber-dominant morphologies. MC3T3-E1 osteoblast-like cells were cultured on all composite films to evaluate the effects of surface nanotopography, chemistry, and wettability on cell behavior. The observations indicated that MC3T3-E1 cell behavior was affected by surface topography, chemistry, and wettability simultaneously and that cells showed strong responses to surface topography. On fiber-dominant surface, cells fully spread with obvious cytoskeleton organization and exhibited significantly higher level of adhesion and proliferation compared with particle- or granule-dominant surfaces. Furthermore, fiber-dominant surface also induced greater expression of mature osteogenic marker osteocalcin and higher mineralization based on RT-PCR and von Kossa staining. The results suggest that topographic modification of chitosan substratum at the nanoscale may be exploited in regulating cell behavior for its applications in tissue engineering.

S180 cell growth on low ion energy plasma treated TiO 2 thin films

NASA Astrophysics Data System (ADS)

Dhayal, Marshal; Cho, Su-In; Moon, Jun Young; Cho, Su-Jin; Zykova, Anna

2008-03-01

X-ray photoelectron spectroscopy (XPS) was used to characterise the effects of low energy (<2 eV) argon ion plasma surface modification of TiO 2 thin films deposited by radio frequency (RF) magnetron sputter system. The low energy argon ion plasma surface modification of TiO 2 in a two-stage hybrid system had increased the proportion of surface states of TiO 2 as Ti 3+. The proportion of carbon atoms as alcohol/ether (C sbnd OX) was decreased with increase the RF power and carbon atoms as carbonyl (C dbnd O) functionality had increased for low RF power treatment. The proportion of C( dbnd O)OX functionality at the surface was decreased at low power and further increase in power has showed an increase in its relive proportion at the surface. The growth of S180 cells was observed and it seems that cells are uniformly spreads on tissue culture polystyrene surface and untreated TiO 2 surfaces whereas small-localised cell free area can be seen on plasma treated TiO 2 surfaces which may be due to decrease in C( dbnd O)OX, increase in C dbnd O and active sites at the surface. A relatively large variation in the surface functionalities with no change in the surface roughness was achieved by different RF plasma treatments of TiO 2 surface whereas no significant change in S180 cell growth with different plasma treatments. This may be because cell growth on TiO 2 was mainly influenced by nano-surface characteristics of oxide films rather than surface chemistry.

Engineering a nanostructured "super surface" with superhydrophobic and superkilling properties.

PubMed

Hasan, Jafar; Raj, Shammy; Yadav, Lavendra; Chatterjee, Kaushik

2015-05-12

We present a nanostructured "super surface" fabricated using a simple recipe based on deep reactive ion etching of a silicon wafer. The topography of the surface is inspired by the surface topographical features of dragonfly wings. The super surface is comprised of nanopillars 4 μm in height and 220 nm in diameter with random inter-pillar spacing. The surface exhibited superhydrophobicity with a static water contact angle of 154.0° and contact angle hysteresis of 8.3°. Bacterial studies revealed the bactericidal property of the surface against both gram negative ( Escherichia coli ) and gram positive ( Staphylococcus aureus ) strains through mechanical rupture of the cells by the sharp nanopillars. The cell viability on these nanostructured surfaces was nearly six-fold lower than on the unmodified silicon wafer. The nanostructured surface also killed mammalian cells (mouse osteoblasts) through mechanical rupture of the cell membrane. Thus, such nanostructured super surfaces could find applications for designing self-cleaning and anti-bacterial surfaces in diverse applications such as microfluidics, surgical instruments, pipelines and food packaging.

Presence of closely spaced protein thiols on the surface of mammalian cells.

PubMed Central

Donoghue, N.; Yam, P. T.; Jiang, X. M.; Hogg, P. J.

2000-01-01

It has been proposed that certain cell-surface proteins undergo redox reactions, that is, transfer of hydrogens and electrons between closely spaced cysteine thiols that can lead to reduction, formation, or interchange of disulfide bonds. This concept was tested using a membrane-impermeable trivalent arsenical to identify closely spaced thiols in cell-surface proteins. We attached the trivalent arsenical, phenylarsenoxide, to the thiol of reduced glutathione to produce 4-(N-(S-glutathionylacetyl)amino)phenylarsenoxide (GSAO). GSAO bound tightly to synthetic, peptide, and protein dithiols like thioredoxin, but not to monothiols. To identify cell-surface proteins that contain closely spaced thiols, we attached a biotin moiety through a spacer arm to the primary amino group of the gamma-glutamyl residue of GSAO (GSAO-B). Incorporation of GSAO-B into proteins was assessed by measuring the biotin using streptavidin-peroxidase. Up to 12 distinct proteins were labeled with GSAO-B on the surface of endothelial and fibrosarcoma cells. The pattern of labeled proteins differed between the different cell types. Protein disulfide isomerase was one of the proteins on the endothelial and fibrosarcoma cell surface that incorporated GSAO-B. These findings demonstrate that the cell-surface environment can support the existence of closely spaced protein thiols and suggest that at least some of these thiols are redox active. PMID:11206065

Capture and release of cells using a temperature-responsive surface that immobilizes an antibody through DNA duplex formation.

PubMed

Kimura, Tsuyoshi; Nakamura, Naoko; Umeda, Kanji; Hashimoto, Yoshihide; Kishida, Akio

We synthesized a temperature-responsive surface that immobilized an antibody via DNA duplex formation for selective capture and release of target cells. Polyethylene films were modified by grafting poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAAm-co-AAc)), which were prepared at various ratios of NIPAAm/AAc. The increased hydrophilicity of P(NIPAAm-co-PAA) film with decreased temperature was confirmed by water contact angle measurement. Single strand DNA (20mer) was chemically immobilized on the surface and then antibody (anti-mouse CD45, mCD45) modified with the complementary single strand DNA was immobilized on the surface through DNA duplex formation. The mCD45 antibody immobilization was confirmed by immunostaining. HeLa cells (mCD45 negative) and mouse bone marrow (BM) cells (mCD45 positive) were adhered on the surfaces at 37 °C. Although HeLa cells were detached by 4 °C incubation, BM cells were still adhered on the surface and then the adhered cells were released by DNase treatment. From these results, it was suggested that cells could be selectively captured and collected by using a film having surface that immobilizes an antibody via DNA duplex formation.

The Role of Titanium Surface Microtopography on Adhesion, Proliferation, Transformation, and Matrix Deposition of Corneal Cells.

PubMed

Zhou, Chengxin; Lei, Fengyang; Chodosh, James; Paschalis, Eleftherios I

2016-04-01

Titanium (Ti) is an excellent implantable biomaterial that can be further enhanced by surface topography optimization. Despite numerous data from orthopedics and dentistry, the effect of Ti surface topography on ocular cells is still poorly understood. In light of the recent adaptation of Ti in the Boston Keratoprosthesis artificial cornea, we attempted to perform an extended evaluation of the effect of Ti surface topography on corneal cell adhesion, proliferation, cytotoxicity, transformation, and matrix deposition. Different surface topographies were generated on medical grade Ti-6Al-4V-ELI (extra-low interstitial), with linearly increased roughness (polished to grit blasted). Biological response was evaluated in vitro using human corneal limbal epithelial (HCLE) cells, stromal fibroblasts (HCF), and endothelial cells (HCEnC). None of the Ti surface topographies caused cytotoxicity to any of the three corneal cell types. However, rough Ti surface inhibited HCLE and HCF cell adhesion and proliferation, while HCEnC proliferation was unaffected. Long-term experiments with HCF revealed that rough Ti surface with R(a) (the arithmetic average of the profile height from the mean line) ≥ 1.15 μm suppressed HCF focal adhesion kinase phosphorylation, changed fibroblast morphology, and caused less aligned and reduced deposition of collagen matrix as compared to smooth Ti (R(a) ≤ 0.08 μm). In the presence of transforming growth factor β1 (TGFβ1) stimulation, rough Ti inhibited alpha-smooth muscle actin (α-SMA) expression and collagen deposition, leading to decreased myofibroblast transformation and disorganization of the collagen fibrils as compared to smooth Ti. This study suggests that Ti surface topography regulates corneal cell behavior in a tissue-dependent manner that varies across the corneal strata. Contrary to the accepted paradigm, smooth surface topography can enhance cell adhesion and proliferation and increase matrix deposition by corneal cells.

Multilayer Choline Phosphate Molecule Modified Surface with Enhanced Cell Adhesion but Resistance to Protein Adsorption.

PubMed

Chen, Xingyu; Yang, Ming; Liu, Botao; Li, Zhiqiang; Tan, Hong; Li, Jianshu

2017-08-22

Choline phosphate (CP), which is a new zwitterionic molecule, and has the reverse order of phosphate choline (PC) and could bind to the cell membrane though the unique CP-PC interaction. Here we modified a glass surface with multilayer CP molecules using surface-initiated atom-transfer radical polymerization (SI-ATRP) and the ring-opening method. Polymeric brushes of (dimethylamino)ethyl methacrylate (DMAEMA) were synthesized by SI-ATRP from the glass surface. Then the grafted PDMAEMA brushes were used to introduce CP groups to fabricate the multilayer CP molecule modified surface. The protein adsorption experiment and cell culture test were used to evaluate the biocompatibility of the modified surfaces by using human umbilical veinendothelial cells (HUVECs). The protein adsorption results demonstrated that the multilayer CP molecule decorated surface could prevent the adsorption of fibrinogen and serum protein. The adhesion and proliferation of cells were improved significantly on the multilayer CP molecule modified surface. Therefore, the biocompatibility of the material surface could be improved by the modified multilayer CP molecule, which exhibits great potential for biomedical applications, e.g., scaffolds in tissue engineering.

Surface Structure Characterization of Aspergillus fumigatus Conidia Mutated in the Melanin Synthesis Pathway and Their Human Cellular Immune Response

PubMed Central

Bayry, Jagadeesh; Beaussart, Audrey; Dufrêne, Yves F.; Sharma, Meenu; Bansal, Kushagra; Kniemeyer, Olaf; Aimanianda, Vishukumar; Brakhage, Axel A.; Kaveri, Srini V.; Kwon-Chung, Kyung J.

2014-01-01

In Aspergillus fumigatus, the conidial surface contains dihydroxynaphthalene (DHN)-melanin. Six-clustered gene products have been identified that mediate sequential catalysis of DHN-melanin biosynthesis. Melanin thus produced is known to be a virulence factor, protecting the fungus from the host defense mechanisms. In the present study, individual deletion of the genes involved in the initial three steps of melanin biosynthesis resulted in an altered conidial surface with masked surface rodlet layer, leaky cell wall allowing the deposition of proteins on the cell surface and exposing the otherwise-masked cell wall polysaccharides at the surface. Melanin as such was immunologically inert; however, deletion mutant conidia with modified surfaces could activate human dendritic cells and the subsequent cytokine production in contrast to the wild-type conidia. Cell surface defects were rectified in the conidia mutated in downstream melanin biosynthetic pathway, and maximum immune inertness was observed upon synthesis of vermelone onward. These observations suggest that although melanin as such is an immunologically inert material, it confers virulence by facilitating proper formation of the A. fumigatus conidial surface. PMID:24818666

Biodegradation and surfactant-mediated biodegradation of diesel fuel by 218 microbial consortia are not correlated to cell surface hydrophobicity.

PubMed

Owsianiak, Mikołaj; Szulc, Alicja; Chrzanowski, Łukasz; Cyplik, Paweł; Bogacki, Mariusz; Olejnik-Schmidt, Agnieszka K; Heipieper, Hermann J

2009-09-01

In this study, we elucidated the role of cell surface hydrophobicity (microbial adhesion to hydrocarbons method, MATH) and the effect of anionic rhamnolipids and nonionic Triton X-100 surfactants on biodegradation of diesel fuel employing 218 microbial consortia isolated from petroleum-contaminated soils. Applied enrichment procedure with floating diesel fuel as a sole carbon source in liquid cultures resulted in consortia of varying biodegradation potential and diametrically different cell surface properties, suggesting that cell surface hydrophobicity is a conserved parameter. Surprisingly, no correlations between cell surface hydrophobicity and biodegradation of diesel fuel were found. Nevertheless, both surfactants altered cell surface hydrophobicity of the consortia in similar manner: increased for the hydrophilic and decreased for the hydrophobic cultures. In addition to this, the surfactants exhibited similar influence on diesel fuel biodegradation: Increase was observed for initially slow-degrading cultures and the opposite for fast degraders. This indicates that in the surfactant-mediated biodegradation, effectiveness of surfactants depends on the specification of microorganisms and not on the type of surfactant. In contrary to what was previously reported for pure strains, cell surface hydrophobicity, as determined by MATH, is not a good descriptor of biodegrading potential for mixed cultures.

Mitigated reactive oxygen species generation leads to an improvement of cell proliferation on poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] functionalized polydimethylsiloxane surfaces.

PubMed

Yu, Ling; Shi, ZhuanZhuan; Gao, LiXia; Li, ChangMing

2015-09-01

In vitro cell-based analysis is strongly affected by material's surface chemical properties. The cell spreading, migration, and proliferation on a substrate surface are initiated and controlled by successful adhesion, particularly for anchor-dependent cells. Unfortunately, polydimethylsiloxane (PDMS), one of the most used polymeric materials for construction of microfluidic and miniaturized biomedical analytic devices, is not a cell-friendly surface because of its inherent hydrophobic property. Herein, a poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] (poly(GMA-co-pEGMA)) polymer brush was synthesized on a PDMS surface through a surface-initiated atom-transfer radical polymerization method. Contact angle and Fourier transform infrared characterization show that the poly (GMA-co-pEGMA) polymer brush functionalization can increase wettability of PDMS and introduce epoxy, hydroxyl, and ether groups into PDMS surface. In vitro cell growth assay demonstrates that cell adhesion and proliferation on poly(GMA-co-pEGMA) polymer brush-functionalized PDMS (poly(GMA-co-pEGMA)@PDMS) are better than on pristine PDMS. Additionally, immobilization of collagen type I (CI) and fibronectin (FN) on poly(GMA-co-pEGMA)@PDMS is better than direct coating of CI and FN on pristine PDMS to promote cell adhesion. Furthermore, increased intracellular reactive oxygen species and cell mitochondrial membrane depolarization, two indicators of cell oxidative stress, are observed from cells growing on pristine PDMS, but not from those on poly(GMA-co-pEGMA)@PDMS. Collectively, we demonstrate that poly(GMA-co-pEGMA) functionalization can enhance cell adhesion and proliferation on PDMS, and thus can be potentially used for microfluidic cell assay devices for cellular physiology study or drug screening. © 2015 Wiley Periodicals, Inc.

Novel INTeraction of MUC4 and galectin: potential pathobiological implications for metastasis in lethal pancreatic cancer.

PubMed

Senapati, Shantibhusan; Chaturvedi, Pallavi; Chaney, William G; Chakraborty, Subhankar; Gnanapragassam, Vinayaga S; Sasson, Aaron R; Batra, Surinder K

2011-01-15

Several studies have reported aberrant expression of MUC4 in pancreatic cancer (PC), which is associated with tumorigenicity and metastasis. Mechanisms through which MUC4 promote metastasis of PC cells to distant organs are poorly defined. Identification of MUC4-galectin-3 interaction and its effect on the adhesion of cancer cells to endothelial cells were done by immunoprecipitation and cell-cell adhesion assays, respectively. Serum galectin-3 level for normal and PC patients were evaluated through ELISA. In the present study, we have provided clinical evidence that the level of galectin-3 is significantly elevated in the sera of PC patients with metastatic disease compared with patients without metastasis (P = 0.04) and healthy controls (P = 0.00001). Importantly, for the first time, we demonstrate that MUC4 present on the surface of circulating PC cells plays a significant role in the transient and reversible attachment (docking) of circulating tumor cells to the surface of endothelial cells. Further, exogenous galectin-3 at concentrations similar to that found in the sera of PC patients interacts with MUC4 via surface glycans such as T antigens, which results in the clustering of MUC4 on the cell surface and a stronger attachment (locking) of circulating tumor cells to the endothelium. Altogether, these findings suggest that PC cell-associated MUC4 helps in the docking of tumor cells on the endothelial surface. During cancer progression, MUC4-galectin-3 interaction-mediated clustering of MUC4 may expose the surface adhesion molecules, which in turn promotes a stronger attachment (locking) of tumor cells to the endothelial surface. ©2010 AACR.

Galactosyltransferase and Concanavalin A Agglutination of Cells

PubMed Central

Podolsky, Daniel K.; Weiser, Milton M.; Mont, J. Thomas La; Isselbacher, Kurt J.

1974-01-01

A correlation has been observed between concanavalin A agglutination of various cell types and the presence of surface membrane galactosyltransferase (1-O-α-D-Galactosyl-myo-inositol:raffinose galactosyltransferase, EC 2.4.1.67) activity. Moreover, a reduction to less than 50% of cell surface galactosyltransferase activity occurred after treatment with concanavalin A; other cell surface glycosyltransferase enzyme activities examined were unaffected by concanavalin A treatment. To confirm the participation of cell surface galactosyltransferase in concanavalin A-induced cell agglutination, the enzyme from rabbit erythrocytes was solubilized by sonication and purified by preparative polyacrylamide gel electrophoresis. It was possible to achieve a purified preparation of rabbit erythrocyte galactosyltransferase by separation on concanavalin A-Sepharose. The purified enzyme showed visible immunoprecipitation (Ouchterlony) with concanavalin A. Furthermore, human erythrocytes, which are not normally agglutinated by concanavalin A, became agglutinable by the lectin when the erythrocytes were preincubated with purified galactosyltransferase. These experiments suggest a direct and possible specific role of cell surface galactosyltransferase enzyme in the mechanism of concanavalin A agglutination of cells. Images PMID:4522801

Alkaline phosphatase, 5'-nucleotidase and magnesium-dependent adenosine triphosphatase activities in the transitional epithelium of the rat urinary bladder.

PubMed

Zhang, S X; Kobayashi, T; Okada, T; García del Saz, E; Seguchi, H

1991-07-01

The cerium-based method was used to demonstrate cytochemically the ultrastructural localization of alkaline phosphatase (ALPase), 5'-nucleotidase (5'-Nase) and magnesium-dependent adenosine triphosphatase (Mg-ATPase) on the transitional epithelium of the rat urinary bladder. The reaction product for ALPase was found on the plasma membrane of all epithelial cells, except the luminal surface of superficial cells. The activity of 5'-Nase appeared on the plasma membrane of all bladder transitional epithelial cells, including the free surface of superficial cells. The Mg-ATPase reaction product was seen on the plasma membrane of superficial, intermediate and basal cells, but never on the luminal surface of superficial cells and it was only occasionally seen on the basal surface. The possible functions of these phosphatases have been discussed, and it was emphasized that the 5'-Nase activity present on the luminal surface of superficial cells may play a special role in the membrane movement of these cells in the transitional epithelium.

Amine-Rich Organic Thin Films for Cell Culture: Possible Electrostatic Effects in Cell-Surface Interactions

NASA Astrophysics Data System (ADS)

Wertheimer, Michael R.; St-Georges-Robillard, Amélie; Lerouge, Sophie; Mwale, Fackson; Elkin, Bentsian; Oehr, Christian; Wirges, Werner; Gerhard, Reimund

2012-11-01

In recent communications from these laboratories, we observed that amine-rich thin organic layers are very efficient surfaces for the adhesion of mammalian cells. We prepare such deposits by plasma polymerization at low pressure, atmospheric pressure, or by vacuum-ultraviolet photo-polymerization. More recently, we have also investigated a commercially available material, Parylene diX AM. In this article we first briefly introduce literature relating to electrostatic interactions between cells, proteins, and charged surfaces. We then present certain selected cell-response results that pertain to applications in orthopedic and cardiovascular medicine: we discuss the influence of surface properties on the observed behaviors of two particular cell lines, human U937 monocytes, and Chinese hamster ovary cells. Particular emphasis is placed on possible electrostatic attractive forces due to positively charged R-NH3+ groups and negatively charged proteins and cells, respectively. Experiments carried out with electrets, polymers with high positive or negative surface potentials are added for comparison.

Effect of surface topography and bioactive properties on early adhesion and growth behavior of mouse preosteoblast MC3T3-E1 cells.

PubMed

Li, Na; Chen, Gang; Liu, Jue; Xia, Yang; Chen, Hanbang; Tang, Hui; Zhang, Feimin; Gu, Ning

2014-10-08

The effects of bioactive properties and surface topography of biomaterials on the adhesion and spreading properties of mouse preosteoblast MC3T3-E1 cells was investigated by preparation of different surfaces. Poly lactic-co-glycolic acid (PLGA) electrospun fibers (ES) were produced as a porous rough surface. In our study, coverslips were used as a substrate for the immobilization of 3,4-dihydroxyphenylalanine (DOPA) and collagen type I (COL I) in the preparation of bioactive surfaces. In addition, COL I was immobilized onto porous electrospun fibers surfaces (E-COL) to investigate the combined effects of bioactive molecules and topography. Untreated coverslips were used as controls. Early adhesion and growth behavior of MC3T3-E1 cells cultured on the different surfaces were studied at 6, 12, and 24 h. Evaluation of cell adhesion and morphological changes showed that the all the surfaces were favorable for promoting the adhesion and spreading of cells. CCK-8 assays and flow cytometry revealed that both topography and bioactive properties were favorable for cell growth. Analysis of β1, α1, α2, α5, α10 and α11 integrin expression levels by immunofluorescence, real-time RT-PCR, and Western blot and indicated that surface topography plays an important role in the early stage of cell adhesion. However, the influence of topography and bioactive properties of surfaces on integrins is variable. Compared with any of the topographic or bioactive properties in isolation, the combined effect of both types of properties provided an advantage for the growth and spreading of MC3T3-E1 cells. This study provides a new insight into the functions and effects of topographic and bioactive modifications of surfaces at the interface between cells and biomaterials for tissue engineering.

Morphological investigations of cells that adhered to the irregular patterned polydimethylsiloxane (PDMS) surface without reagents.

PubMed

Chung, Sung Hee; Min, Junhong

2009-07-01

Polydimethylsiloxane (PDMS) surface consisting irregular pattern was investigated to develop cell-based biochip using PDMS. PDMS surface was modified with nano- and micro-combined patterns using surface deformation technology. Hydrophobicity of nano-patterned PDMS surface was sustained. Nevertheless it has irregular patterns consisting of micro- and nano-patterns. According to atomic force microscopy (AFM), scanning electron microscopy (SEM) and confocal microscopy results by immunostaining method, human mammary epithelial cells (HMEC) adhered well on irregularly patterned surface without any reagents such as gelatin and collagen, compared to commercial culture dish. It implies PDMS material can be utilized as template for cell-based biochip without any reagents.

Directional Spread of Surface-Associated Retroviruses Regulated by Differential Virus-Cell Interactions▿ †

PubMed Central

Sherer, Nathan M.; Jin, Jing; Mothes, Walther

2010-01-01

The spread of viral infections involves the directional progression of virus particles from infected cells to uninfected target cells. Prior to entry, the binding of virus particles to specific cell surface receptors can trigger virus surfing, an actin-dependent lateral transport of viruses toward the cell body (M. J. Lehmann et al., J. Cell Biol. 170:317-325, 2005; M. Schelhaas, et al., PLoS Pathog. 4:e1000148, 2008; J. L. Smith, D. S. Lidke, and M. A. Ozbun, Virology 381:16-21, 2008). Here, we have used live-cell imaging to demonstrate that for cells chronically infected with the gammaretrovirus murine leukemia virus in which receptor has been downregulated, a significant portion of completely assembled virus particles are not immediately released into the supernatant but retain long-term association with the cell surface. Retention can be attributed, at least in part, to nonspecific particle attachment to cell surface glycosylaminoglycans. In contrast to virus surfing, viruses retained at the surface of infected cells undergo a lateral motility that is random and actin independent. This diffusive motility can be abruptly halted and converted into inward surfing after treatment with Polybrene, a soluble cation that increases virus-cell adsorption. In the absence of Polybrene, particle diffusion allows for an outward flow of viruses to the infected cell periphery. Peripheral particles are readily captured by and transmitted to neighboring uninfected target cells in a directional fashion. These data demonstrate a surface-based mechanism for the directional spread of viruses regulated by differential virus-cell interactions. PMID:20089647

Surface wettability of plasma SiOx:H nanocoating-induced endothelial cells' migration and the associated FAK-Rho GTPases signalling pathways

PubMed Central

Shen, Yang; Wang, Guixue; Huang, Xianliang; Zhang, Qin; Wu, Jiang; Tang, Chaojun; Yu, Qingsong; Liu, Xiaoheng

2012-01-01

Vascular endothelial cell (EC) adhesion and migration are essential processes in re-endothelialization of implanted biomaterials. There is no clear relationship and mechanism between EC adhesion and migration behaviour on surfaces with varying wettabilities. As model substrates, plasma SiOx:H nanocoatings with well-controlled surface wettability (with water contact angles in the range of 98.5 ± 2.3° to 26.3 ± 4.0°) were used in this study to investigate the effects of surface wettability on cell adhesion/migration and associated protein expressions in FAK-Rho GTPases signalling pathways. It was found that EC adhesion/migration showed opposite behaviour on the hydrophilic and hydrophobic surfaces (i.e. hydrophobic surfaces promoted EC migration but were anti-adhesions). The number of adherent ECs showed a maximum on hydrophilic surfaces, while cells adhered to hydrophobic surfaces exhibited a tendency for cell migration. The focal adhesion kinase (FAK) inhibitor targeting the Y-397 site of FAK could significantly inhibit cell adhesion/migration, suggesting that EC adhesion and migration on surfaces with different wettabilities involve (p)FAK and its downstream signalling pathways. Western blot results suggested that the FAK-Rho GTPases signalling pathways were correlative to EC migration on hydrophobic plasma SiOx:H surfaces, but uncertain to hydrophilic surfaces. This work demonstrated that surface wettability could induce cellular behaviours that were associated with different cellular signalling events. PMID:21715399

Osteoblastlike cell adhesion on titanium surfaces modified by plasma nitriding.

PubMed

da Silva, Jose Sandro Pereira; Amico, Sandro Campos; Rodrigues, Almir Olegario Neves; Barboza, Carlos Augusto Galvao; Alves, Clodomiro; Croci, Alberto Tesconi

2011-01-01

The aim of this study was to evaluate the characteristics of various titanium surfaces modified by cold plasma nitriding in terms of adhesion and proliferation of rat osteoblastlike cells. Samples of grade 2 titanium were subjected to three different surface modification processes: polishing, nitriding by plasma direct current, and nitriding by cathodic cage discharge. To evaluate the effect of the surface treatment on the cellular response, the adhesion and proliferation of osteoblastlike cells (MC3T3) were quantified and the results were analyzed by Kruskal-Wallis and Friedman statistical tests. Cellular morphology was observed by scanning electron microscopy. There was more MC3T3 cell attachment on the rougher surfaces produced by cathodic cage discharge compared with polished samples (P < .05). Plasma nitriding improves titanium surface roughness and wettability, leading to osteoblastlike cell adhesion.

Targeted Identification of Metastasis-associated Cell-surface Sialoglycoproteins in Prostate Cancer*

PubMed Central

Yang, Lifang; Nyalwidhe, Julius O.; Guo, Siqi; Drake, Richard R.; Semmes, O. John

2011-01-01

Covalent attachment of carbohydrates to proteins is one of the most common post-translational modifications. At the cell surface, sugar moieties of glycoproteins contribute to molecular recognition events involved in cancer metastasis. We have combined glycan metabolic labeling with mass spectrometry analysis to identify and characterize metastasis-associated cell surface sialoglycoproteins. Our model system used syngeneic prostate cancer cell lines derived from PC3 (N2, nonmetastatic, and ML2, highly metastatic). The metabolic incorporation of AC4ManNAz and subsequent specific labeling of cell surface sialylation was confirmed by flow cytometry and confocal microscopy. Affinity isolation of the modified sialic-acid containing cell surface proteins via click chemistry was followed by SDS-PAGE separation and liquid chromatography-tandem MS analysis. We identified 324 proteins from N2 and 372 proteins of ML2. Using conservative annotation, 64 proteins (26%) from N2 and 72 proteins (29%) from ML2 were classified as extracellular or membrane-associated glycoproteins. A selective enrichment of sialoglycoproteins was confirmed. When compared with global proteomic analysis of the same cells, the proportion of identified glycoprotein and cell-surface proteins were on average threefold higher using the selective capture approach. Functional clustering of differentially expressed proteins by Ingenuity Pathway Analysis revealed that the vast majority of glycoproteins overexpressed in the metastatic ML2 subline were involved in cell motility, migration, and invasion. Our approach effectively targeted surface sialoglycoproteins and efficiently identified proteins that underlie the metastatic potential of the ML2 cells. PMID:21447706

Targeted identification of metastasis-associated cell-surface sialoglycoproteins in prostate cancer.

PubMed

Yang, Lifang; Nyalwidhe, Julius O; Guo, Siqi; Drake, Richard R; Semmes, O John

2011-06-01

Covalent attachment of carbohydrates to proteins is one of the most common post-translational modifications. At the cell surface, sugar moieties of glycoproteins contribute to molecular recognition events involved in cancer metastasis. We have combined glycan metabolic labeling with mass spectrometry analysis to identify and characterize metastasis-associated cell surface sialoglycoproteins. Our model system used syngeneic prostate cancer cell lines derived from PC3 (N2, nonmetastatic, and ML2, highly metastatic). The metabolic incorporation of AC(4)ManNAz and subsequent specific labeling of cell surface sialylation was confirmed by flow cytometry and confocal microscopy. Affinity isolation of the modified sialic-acid containing cell surface proteins via click chemistry was followed by SDS-PAGE separation and liquid chromatography-tandem MS analysis. We identified 324 proteins from N2 and 372 proteins of ML2. Using conservative annotation, 64 proteins (26%) from N2 and 72 proteins (29%) from ML2 were classified as extracellular or membrane-associated glycoproteins. A selective enrichment of sialoglycoproteins was confirmed. When compared with global proteomic analysis of the same cells, the proportion of identified glycoprotein and cell-surface proteins were on average threefold higher using the selective capture approach. Functional clustering of differentially expressed proteins by Ingenuity Pathway Analysis revealed that the vast majority of glycoproteins overexpressed in the metastatic ML2 subline were involved in cell motility, migration, and invasion. Our approach effectively targeted surface sialoglycoproteins and efficiently identified proteins that underlie the metastatic potential of the ML2 cells.

Characteristic Changes in Cell Surface Glycosylation Accompany Intestinal Epithelial Cell (IEC) Differentiation: High Mannose Structures Dominate the Cell Surface Glycome of Undifferentiated Enterocytes.

PubMed

Park, Dayoung; Brune, Kristin A; Mitra, Anupam; Marusina, Alina I; Maverakis, Emanual; Lebrilla, Carlito B

2015-11-01

Changes in cell surface glycosylation occur during the development and differentiation of cells and have been widely correlated with the progression of several diseases. Because of their structural diversity and sensitivity to intra- and extracellular conditions, glycans are an indispensable tool for analyzing cellular transformations. Glycans present on the surface of intestinal epithelial cells (IEC) mediate interactions with billions of native microorganisms, which continuously populate the mammalian gut. A distinct feature of IECs is that they differentiate as they migrate upwards from the crypt base to the villus tip. In this study, nano-LC/ESI QTOF MS profiling was used to characterize the changes in glycosylation that correspond to Caco-2 cell differentiation. As Caco-2 cells differentiate to form a brush border membrane, a decrease in high mannose type glycans and a concurrent increase in fucosylated and sialylated complex/hybrid type glycans were observed. At day 21, when cells appear to be completely differentiated, remodeling of the cell surface glycome ceases. Differential expression of glycans during IEC maturation appears to play a key functional role in regulating the membrane-associated hydrolases and contributes to the mucosal surface innate defense mechanisms. Developing methodologies to rapidly identify changes in IEC surface glycans may lead to a rapid screening approach for a variety of disease states affecting the GI tract. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Isolation by cell-column chromatography of immunoglobulins specific for cell surface carbohydrates

PubMed Central

1977-01-01

A new method of affinity chromatography using glutaraldehyde-fixed cells immobilized on Sephadex beads has been used to isolate immunoglobulins (Ig's) specific for cell surface glycoproteins. Ig's that specifically bound and agglutinated the same cells as those originally fixed on the columns were isolated from nonimmune sera of various species. Periodate treatment of the cell-columns and the free cells destroyed their ability to bind the Ig's, and the binding of the Ig's to untreated cells was inhibited by monosaccharides such as D- galactose and sialic acid. The binding of antibodies directed against cell surfaces obtained by immunizing animals with the same mouse tumor cell lines used on the columns (P388 and EL4) was not inhibited by various saccharides. Surface glycoproteins obtained from the mouse tumor cells by immunoprecipitation with the column-isolated Ig's yielded specific electrophoretic patterns that differed from those obtained using Ig's from the sera of rabbits immunized with the tumor cells. The data suggest that the Ig's isolated by cell-column chromatography were directed against carbohydrates, probably those in terminal positions of the polysaccharide portions of the tumor cell surface glycoproteins. Column-isolated Ig's specific for carbohydrates were also useful in studies of cell interactions in nonmammalian systems including Dictyostelium discoideum and Saccharomyces cerevisiae. The cell-column method appears to be adaptable to the isolation of a variety of molecules in addition to antibodies. PMID:833547

Neuron-like PC12 cell patterning on a photoactive self-assembled monolayer.

PubMed

Cheng, Nan; Cao, Xudong

2013-11-01

A new approach to pattern cells using photochemistry and self-assembled monolayer (SAM) was described in this study. Photocleavable 4,5-dimethoxy-2-nitrobenzyl chloroformate (NVOC) protected amine on an alkanethiol-gold SAM was developed for cell patterning. The cleavage of NVOC and the deprotection of amines on the SAM were controlled spatially by two sequential UV exposures with a photomask. Biomolecule patterning was achieved by introducing cell nonadhesive poly(ethylene glycol) after the first exposure and subsequently cell adhesive protein laminin after the second exposure to create surface cell adhesiveness differential for cell patterning. UV-Vis spectrophotometry was used to determine the photolysis of caged self-assembled molecules; in addition, water contact angle, atomic force microscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy were used to characterize properties of different surfaces. To test the efficacy of resulting surfaces in patterning cells, a neuron-like cell line, PC12 cell line, was used. The in vitro cell studies showed successful PC12 cell patterns on the photoactive SAM surfaces. This patterning technique is unique in that it does not rely on cell adhesive or nonadhesive properties of the starting base material as both cell adhesive and cell nonadhesive molecules were individually introduced onto the base material surface through photo-uncaging at preselected regions for the ultimate cell patterning. Copyright © 2013 Wiley Periodicals, Inc.

Correlation of Cell Surface Biomarker Expression Levels with Adhesion Contact Angle Measured by Lateral Microscopy.

PubMed

Walz, Jenna A; Mace, Charles R

2018-06-05

Immunophenotyping is typically achieved using flow cytometry, but any influence a biomarker may have on adhesion or surface recognition cannot be determined concurrently. In this manuscript, we demonstrate the utility of lateral microscopy for correlating cell surface biomarker expression levels with quantitative descriptions of cell morphology. With our imaging system, we observed single cells from two T cell lines and two B cell lines adhere to antibody-coated substrates and quantified this adhesion using contact angle measurements. We found that SUP-T1 and CEM CD4+ cells, both of which express similar levels of CD4, experienced average changes in contact angle that were not statistically different from one another on surfaces coated in anti-CD4. However, MAVER-1 and BJAB K20 cells, both of which express different levels of CD20, underwent average changes in contact angle that were significantly different from one another on surfaces coated in anti-CD20. Our results indicate that changes in cell contact angles on antibody-coated substrates reflect the expression levels of corresponding antigens on the surfaces of cells as determined by flow cytometry. Our lateral microscopy approach offers a more reproducible and quantitative alternative to evaluate adhesion compared to commonly used wash assays and can be extended to many additional immunophenotyping applications to identify cells of interest within heterogeneous populations.

Control of proliferation and osteogenic differentiation of human dental-pulp-derived stem cells by distinct surface structures.

PubMed

Kolind, K; Kraft, D; Bøggild, T; Duch, M; Lovmand, J; Pedersen, F S; Bindslev, D A; Bünger, C E; Foss, M; Besenbacher, F

2014-02-01

The ability to control the behavior of stem cells provides crucial benefits, for example, in tissue engineering and toxicity/drug screening, which utilize the stem cell's capacity to engineer new tissues for regenerative purposes and the testing of new drugs in vitro. Recently, surface topography has been shown to influence stem cell differentiation; however, general trends are often difficult to establish due to differences in length scales, surface chemistries and detailed surface topographies. Here we apply a highly versatile screening approach to analyze the interplay of surface topographical parameters on cell attachment, morphology, proliferation and osteogenic differentiation of human mesenchymal dental-pulp-derived stem cells (DPSCs) cultured with and without osteogenic differentiation factors in the medium (ODM). Increasing the inter-pillar gap size from 1 to 6 μm for surfaces with small pillar sizes of 1 and 2 μm resulted in decreased proliferation and in more elongated cells with long pseudopodial protrusions. The same alterations of pillar topography, up to an inter-pillar gap size of 4 μm, also resulted in enhanced mineralization of DPSCs cultured without ODM, while no significant trend was observed for DPSCs cultured with ODM. Generally, cells cultured without ODM had a larger deposition of osteogenic markers on structured surfaces relative to the unstructured surfaces than what was found when culturing with ODM. We conclude that the topographical design of biomaterials can be optimized for the regulation of DPSC differentiation and speculate that the inclusion of ODM alters the ability of the cells to sense surface topographical cues. These results are essential in order to transfer the use of this highly proliferative, easily accessible stem cell into the clinic for use in cell therapy and regenerative medicine. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Analysis of high-throughput screening reveals the effect of surface topographies on cellular morphology.

PubMed

Hulsman, Marc; Hulshof, Frits; Unadkat, Hemant; Papenburg, Bernke J; Stamatialis, Dimitrios F; Truckenmüller, Roman; van Blitterswijk, Clemens; de Boer, Jan; Reinders, Marcel J T

2015-03-01

Surface topographies of materials considerably impact cellular behavior as they have been shown to affect cell growth, provide cell guidance, and even induce cell differentiation. Consequently, for successful application in tissue engineering, the contact interface of biomaterials needs to be optimized to induce the required cell behavior. However, a rational design of biomaterial surfaces is severely hampered because knowledge is lacking on the underlying biological mechanisms. Therefore, we previously developed a high-throughput screening device (TopoChip) that measures cell responses to large libraries of parameterized topographical material surfaces. Here, we introduce a computational analysis of high-throughput materiome data to capture the relationship between the surface topographies of materials and cellular morphology. We apply robust statistical techniques to find surface topographies that best promote a certain specified cellular response. By augmenting surface screening with data-driven modeling, we determine which properties of the surface topographies influence the morphological properties of the cells. With this information, we build models that predict the cellular response to surface topographies that have not yet been measured. We analyze cellular morphology on 2176 surfaces, and find that the surface topography significantly affects various cellular properties, including the roundness and size of the nucleus, as well as the perimeter and orientation of the cells. Our learned models capture and accurately predict these relationships and reveal a spectrum of topographies that induce various levels of cellular morphologies. Taken together, this novel approach of high-throughput screening of materials and subsequent analysis opens up possibilities for a rational design of biomaterial surfaces. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Targeted cell adhesion on selectively micropatterned polymer arrays on a poly(dimethylsiloxane) surface.

PubMed

Tang, Linzhi; Min, Junhong; Lee, Eun-Cheol; Kim, Jong Sung; Lee, Nae Yoon

2010-02-01

Herein, we introduce the fabrication of polymer micropattern arrays on a chemically inert poly(dimethylsiloxane) (PDMS) surface and employ them for the selective adhesion of cells. To fabricate the micropattern arrays, a mercapto-ester-based photocurable adhesive was coated onto a mercaptosilane-coated PDMS surface and photopolymerized using a photomask to obtain patterned arrays at the microscale level. Robust polymer patterns, 380 microm in diameter, were successfully fabricated onto a PDMS surface, and cells were selectively targeted toward the patterned regions. Next, the performance of the cell adhesion was observed by anchoring cell adhesive linker, an RGD oligopeptide, on the surface of the mercapto-ester-based adhesive-cured layer. The successful anchoring of the RGD linker was confirmed through various surface characterizations such as water contact angle measurement, XPS analysis, FT-IR analysis, and AFM measurement. The micropatterning of a photocurable adhesive onto a PDMS surface can provide high structural rigidity, a highly-adhesive surface, and a physical pathway for selective cell adhesion, while the incorporated polymer micropattern arrays inside a PDMS microfluidic device can serve as a microfluidic platform for disease diagnoses and high-throughput drug screening.

High efficiency silicon nanowire/organic hybrid solar cells with two-step surface treatment.

PubMed

Wang, Jianxiong; Wang, Hao; Prakoso, Ari Bimo; Togonal, Alienor Svietlana; Hong, Lei; Jiang, Changyun; Rusli

2015-03-14

A simple two-step surface treatment process is proposed to boost the efficiency of silicon nanowire/PEDOT:PSS hybrid solar cells. The Si nanowires (SiNWs) are first subjected to a low temperature ozone treatment to form a surface sacrificial oxide, followed by a HF etching process to partially remove the oxide. TEM investigation demonstrates that a clean SiNW surface is achieved after the treatment, in contrast to untreated SiNWs that have Ag nanoparticles left on the surface from the metal-catalyzed etching process that is used to form the SiNWs. The cleaner SiNW surface achieved and the thin layer of residual SiO2 on the SiNWs have been found to improve the performance of the hybrid solar cells. Overall, the surface recombination of the hybrid SiNW solar cells is greatly suppressed, resulting in a remarkably improved open circuit voltage of 0.58 V. The power conversion efficiency has also increased from about 10% to 12.4%. The two-step surface treatment method is promising in enhancing the photovoltaic performance of the hybrid silicon solar cells, and can also be applied to other silicon nanostructure based solar cells.

Engineering Novel and Improved Biocatalysts by Cell Surface Display

PubMed Central

Smith, Mason R.; Khera, Eshita; Wen, Fei

2017-01-01

Biocatalysts, especially enzymes, have the ability to catalyze reactions with high product selectivity, utilize a broad range of substrates, and maintain activity at low temperature and pressure. Therefore, they represent a renewable, environmentally friendly alternative to conventional catalysts. Most current industrial-scale chemical production processes using biocatalysts employ soluble enzymes or whole cells expressing intracellular enzymes. Cell surface display systems differ by presenting heterologous enzymes extracellularly, overcoming some of the limitations associated with enzyme purification and substrate transport. Additionally, coupled with directed evolution, cell surface display is a powerful platform for engineering enzymes with enhanced properties. In this review, we will introduce the molecular and cellular principles of cell surface display and discuss how it has been applied to engineer enzymes with improved properties as well as to develop surface-engineered microbes as whole-cell biocatalysts. PMID:29056821

Modeling Bacteria Surface Acid-Base Properties: The Overprint Of Biology

NASA Astrophysics Data System (ADS)

Amores, D. R.; Smith, S.; Warren, L. A.

2009-05-01

Bacteria are ubiquitous in the environment and are important repositories for metals as well as nucleation templates for a myriad of secondary minerals due to an abundance of reactive surface binding sites. Model elucidation of whole cell surface reactivity simplifies bacteria as viable but static, i.e., no metabolic activity, to enable fits of microbial data sets from models derived from mineral surfaces. Here we investigate the surface proton charging behavior of live and dead whole cell cyanobacteria (Synechococcus sp.) harvested from a single parent culture by acid-base titration using a Fully Optimized ContinUouS (FOCUS) pKa spectrum method. Viability of live cells was verified by successful recultivation post experimentation, whereas dead cells were consistently non-recultivable. Surface site identities derived from binding constants determined for both the live and dead cells are consistent with molecular analogs for organic functional groups known to occur on microbial surfaces: carboxylic (pKa = 2.87-3.11), phosphoryl (pKa = 6.01-6.92) and amine/hydroxyl groups (pKa = 9.56-9.99). However, variability in total ligand concentration among the live cells is greater than those between the live and dead. The total ligand concentrations (LT, mol- mg-1 dry solid) derived from the live cell titrations (n=12) clustered into two sub-populations: high (LT = 24.4) and low (LT = 5.8), compared to the single concentration for the dead cell titrations (LT = 18.8; n=5). We infer from these results that metabolic activity can substantively impact surface reactivity of morphologically identical cells. These results and their modeling implications for bacteria surface reactivities will be discussed.

Material- and feature-dependent effects on cell adhesion to micro injection moulded medical polymers.

PubMed

Choi, Seong Ying; Habimana, Olivier; Flood, Peter; Reynaud, Emmanuel G; Rodriguez, Brian J; Zhang, Nan; Casey, Eoin; Gilchrist, Michael D

2016-09-01

Two polymers, polymethylmethacrylate (PMMA) and cyclic olefin copolymer (COC), containing a range of nano- to micron- roughness surfaces (Ra 0.01, 0.1, 0.4, 1.0, 2.0, 3.2 and 5.0μm) were fabricated using electrical discharge machining (EDM) and replicated using micro injection moulding (μIM). Polymer samples were characterized using optical profilometry, atomic force microscopy (AFM) and water surface contact angle. Cell adhesion tests were carried out using bacterial Pseudomonas fluorescens and mammalian Madin-Darby Canine Kidney (MDCK) cells to determine the effect of surface hydrophobicity, surface roughness and stiffness. It is found that there are features which gave insignificant differences (feature-dependent effect) in cell adhesion, albeit a significant difference in the physicochemical properties (material-dependent effect) of substrata. In bacterial cell adhesion, the strongest feature-dependence is found at Ra 0.4μm surfaces, with material-dependent effects strongest at Ra 0.01μm. Ra 0.1μm surfaces exhibited strongest feature-dependent effects and Ra 5.0μm has strongest material-dependent effects on mammalian cell adhesion. Bacterial cell adhesion is found to be favourable to hydrophobic surfaces (COC), with the lowest adhesion at Ra 0.4μm for both materials. Mammalian cell adhesion is lowest in Ra 0.1μm and highest in Ra 1.0μm, and generally favours hydrophilic surfaces (PMMA). These findings can be used as a basis for developing medical implants or microfluidic devices using micro injection moulding for diagnostic purposes, by tuning the cell adhesion on different areas containing different surface roughnesses on the diagnostic microfluidic devices or medical implants. Copyright © 2016 Elsevier B.V. All rights reserved.

Double-chimera proteins to enhance recruitment of endothelial cells and their progenitor cells.

PubMed

Behjati, M; Kazemi, M; Hashemi, M; Zarkesh-Esfahanai, S H; Bahrami, E; Hashemi-Beni, B; Ahmadi, R

2013-08-20

Enhanced attraction of selective vascular reparative cells is of great importance in order to increase vascular patency after endovascular treatments. We aimed to evaluate efficient attachment of endothelial cells and their progenitors on surfaces coated with mixture of specific antibodies, L-selectin and VE-cadherin, with prohibited platelet attachment. The most efficient conditions for coating of L-selectin-Fc chimera and VE-cadherin-Fc chimera proteins were first determined by protein coating on ELISA plates. The whole processes were repeated on titanium substrates, which are commonly used to coat stents. Endothelial progenitor cells (EPCs) and human umbilical vein endothelial cells (HUVECs) were isolated and characterized by flow cytometry. Cell attachment, growth, proliferation, viability and surface cytotoxicity were evaluated using nuclear staining and MTT assay. Platelet and cell attachment were evaluated using scanning electron microscopy. Optimal concentration of each protein for surface coating was 50 ng/ml. The efficacy of protein coating was both heat and pH independent. Calcium ions had significant impact on simultaneous dual-protein coating (P<0.05). Coating stability data revealed more than one year stability for these coated proteins at 4°C. L-selectin and VE-cadherin (ratio of 50:50) coated surface showed highest EPC and HUVEC attachment, viability and proliferation compared to single protein coated and non-coated titanium surfaces (P<0.05). This double coated surface did not show any cytotoxic effect. Surfaces coated with L-selectin and VE-cadherin are friendly surface for EPC and endothelial cell attachment with less platelet attachment. These desirable factors make the L-selectin and VE-cadherin coated surfaces perfect candidate endovascular device. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Development of an electro-responsive platform for the controlled transfection of mammalian cells

NASA Astrophysics Data System (ADS)

Hook, Andrew L.; Thissen, Helmut W.; Hayes, Jason P.; Voelcker, Nicolas H.

2005-02-01

The recent development of living microarrays as novel tools for the analysis of gene expression in an in-situ environment promises to unravel gene function within living organisms. In order to significantly enhance microarray performance, we are working towards electro-responsive DNA transfection chips. This study focuses on the control of DNA adsorption and desorption by appropriate surface modification of highly doped p++ silicon. Silicon was modified by plasma polymerisation of allylamine (ALAPP), a non-toxic surface that sustains cell growth. Subsequent high surface density grafting of poly(ethylene oxide) formed a layer resistant to biomolecule adsorption and cell attachment. Spatially controlled excimer laser ablation of the surface produced micron resolution patterns of re-exposed plasma polymer whilst the rest of the surface remained non-fouling. We observed electro-stimulated preferential adsorption of DNA to the ALAPP surface and subsequent desorption by the application of a negative bias. Cell culture experiments with HEK 293 cells demonstrated efficient and controlled transfection of cells using the expression of green fluorescent protein as a reporter. Thus, these chemically patterned surfaces are promising platforms for use as living microarrays.

Surface chemistry of gold nanorods: origin of cell membrane damage and cytotoxicity

NASA Astrophysics Data System (ADS)

Wang, Liming; Jiang, Xiumei; Ji, Yinglu; Bai, Ru; Zhao, Yuliang; Wu, Xiaochun; Chen, Chunying

2013-08-01

We investigated how surface chemistry influences the interaction between gold nanorods (AuNRs) and cell membranes and the subsequent cytotoxicity arising from them in a serum-free cell culture system. Our results showed that the AuNRs coated with cetyl trimethylammonium bromide (CTAB) molecules can generate defects in the cell membrane and induce cell death, mainly due to the unique bilayer structure of CTAB molecules on the surface of the rods rather than their charge. Compared to CTAB-capped nanorods, positively charged polyelectrolyte-coated, i.e. poly(diallyldimethyl ammonium chloride) (PDDAC), AuNRs show improved biocompatibility towards cells. Thus, the present results indicate that the nature of surface molecules, especially their packing structures on the surface of AuNRs rather than surface charge, play a more crucial role in determining cytotoxicity. These findings about interfacial interactions could also explain the effects of internalized AuNRs on the structures or functions of organelles. This study will help understanding of the toxic nature of AuNRs and guide rational design of the surface chemistry of AuNRs for good biocompatibility in pharmaceutical therapy.

Surface-modified gold nanorods for specific cell targeting

NASA Astrophysics Data System (ADS)

Wang, Chan-Ung; Arai, Yoshie; Kim, Insun; Jang, Wonhee; Lee, Seonghyun; Hafner, Jason H.; Jeoung, Eunhee; Jung, Deokho; Kwon, Youngeun

2012-05-01

Gold nanoparticles (GNPs) have unique properties that make them highly attractive materials for developing functional reagents for various biomedical applications including photothermal therapy, targeted drug delivery, and molecular imaging. For in vivo applications, GNPs need to be prepared with very little or negligible cytotoxicitiy. Most GNPs are, however, prepared using growth-directing surfactants such as cetyl trimethylammonium bromide (CTAB), which are known to have considerable cytotoxicity. In this paper, we describe an approach to remove CTAB to a non-toxic concentration. We optimized the conditions for surface modification with methoxypolyethylene glycol thiol (mPEG), which replaced CTAB and formed a protective layer on the surface of gold nanorods (GNRs). The cytotoxicities of pristine and surface-modified GNRs were measured in primary human umbilical vein endothelial cells and human cell lines derived from hepatic carcinoma cells, embryonic kidney cells, and thyroid papillary carcinoma cells. Cytotoxicity assays revealed that treating cells with GNRs did not significantly affect cell viability except for thyroid papillary carcinoma cells. Thyroid cancer cells were more susceptible to residual CTAB, so CTAB had to be further removed by dialysis in order to use GNRs for thyroid cell targeting. PEGylated GNRs are further modified to present monoclonal antibodies that recognize a specific surface marker, Na-I symporter, for thyroid cells. Antibody-conjugated GNRs specifically targeted human thyroid cells in vitro.

A theoretical approach to the relationship between wettability and surface microstructures of epidermal cells and structured cuticles of flower petals

PubMed Central

Taneda, Haruhiko; Watanabe-Taneda, Ayako; Chhetry, Rita; Ikeda, Hiroshi

2015-01-01

Background and Aims The epidermal surface of a flower petal is composed of convex cells covered with a structured cuticle, and the roughness of the surface is related to the wettability of the petal. If the surface remains wet for an excessive amount of time the attractiveness of the petal to floral visitors may be impaired, and adhesion of pathogens may be promoted. However, it remains unclear how the epidermal cells and structured cuticle contribute to surface wettability of a petal. Methods By considering the additive effects of the epidermal cells and structured cuticle on petal wettability, a thermodynamic model was developed to predict the wetting mode and contact angle of a water droplet at a minimum free energy. Quantitative relationships between petal wettability and the geometries of the epidermal cells and the structured cuticle were then estimated. Measurements of contact angles and anatomical traits of petals were made on seven herbaceous species commonly found in alpine habitats in eastern Nepal, and the measured wettability values were compared with those predicted by the model using the measured geometries of the epidermal cells and structured cuticles. Key Results The model indicated that surface wettability depends on the height and interval between cuticular steps, and on a height-to-width ratio for epidermal cells if a thick hydrophobic cuticle layer covers the surface. For a petal epidermis consisting of lenticular cells, a repellent surface results when the cuticular step height is greater than 0·85 µm and the height-to-width ratio of the epidermal cells is greater than 0·3. For an epidermis consisting of papillate cells, a height-to-width ratio of greater than 1·1 produces a repellent surface. In contrast, if the surface is covered with a thin cuticle layer, the petal is highly wettable (hydrophilic) irrespective of the roughness of the surface. These predictions were supported by the measurements of petal wettability made on flowers of alpine species. Conclusions The results indicate that surface roughness caused by epidermal cells and a structured cuticle produces a wide range of petal wettability, and that this can be successfully modelled using a thermodynamic approach. PMID:25851137

3D Plasma Nanotextured® Polymeric Surfaces for Protein or Antibody Arrays, and Biomolecule and Cell Patterning.

PubMed

Tsougeni, Katerina; Ellinas, Kosmas; Koukouvinos, George; Petrou, Panagiota S; Tserepi, Angeliki; Kakabakos, Sotirios E; Gogolides, Evangelos

2018-01-01

Plasma micro-nanotexturing is a generic technology for topographical and chemical modification of surfaces and their implementation in microfluidics and microarrays. Nanotextured surfaces with desirable chemical functionality (and wetting behavior) have shown excellent biomolecule immobilization and cell adhesion. Specifically, nanotextured hydrophilic areas show (a) strong binding of biomolecules and (b) strong adhesion of cells, while nanotextured superhydrophobic areas show null adsorption of (a) proteins and (b) cells. Here we describe the protocols for (a) biomolecule adsorption control on nanotextured surfaces for microarray fabrication and (b) cell adhesion on such surfaces. 3D plasma nanotextured® substrates are commercialized through Nanoplasmas private company, a spin-off of the National Centre for Scientific Research Demokritos.

Cell surface engineering of industrial microorganisms for biorefining applications.

PubMed

Tanaka, Tsutomu; Kondo, Akihiko

2015-11-15

In order to decrease carbon emissions and negative environmental impacts of various pollutants, biofuel/biochemical production should be promoted for replacing fossil-based industrial processes. Utilization of abundant lignocellulosic biomass as a feedstock has recently become an attractive option. In this review, we focus on recent efforts of cell surface display using industrial microorganisms such as Escherichia coli and yeast. Cell surface display is used primarily for endowing cellulolytic activity on the host cells, and enables direct fermentation to generate useful fuels and chemicals from lignocellulosic biomass. Cell surface display systems are systematically summarized, and the drawbacks/perspectives as well as successful application of surface display for industrial biotechnology are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

Increasing binding density of yeast cells by control of surface charge with allylamine grafting to ion modified polymer surfaces.

PubMed

Tran, Clara T H; Kondyurin, Alexey; Chrzanowski, Wojciech; Bilek, Marcela M M; McKenzie, David R

2014-10-01

Plasma immersion ion implantation (PIII) treatment of polymers creates a biointerface capable of direct covalent immobilization of biomolecules. The immobilization of protein molecules is achieved by covalent bonds formed between embedded radicals on the treated surface and amino acid side chains and cells can be immobilized through cell-wall proteins. The attachment density of negatively charged entities on a PIII treated surface is inhibited by its negative surface charge at neutral pH. To reduce the negative charge of PIII treated surfaces in phosphate buffer (pH 7.4, 11mM), we develop an effective approach of grafting allylamine monomers onto the treated surface. The results reveal reactions between allylamine and radicals on the PIII treated surface. One of these triggers polymerization, increasing the number of amine groups grafted. As a consequence, the PIII treated polystyrene surface after allylamine exposure becomes more hydrophobic and less negatively charged in phosphate buffer. Using yeast cells as an example, we have shown a significant improvement (6-15 times) of cell density immobilized on the PIII treated surface after exposure to allylamine. Copyright © 2014 Elsevier B.V. All rights reserved.

Computational design of nanoparticle drug delivery systems for selective targeting

NASA Astrophysics Data System (ADS)

Duncan, Gregg A.; Bevan, Michael A.

2015-09-01

Ligand-functionalized nanoparticles capable of selectively binding to diseased versus healthy cell populations are attractive for improved efficacy of nanoparticle-based drug and gene therapies. However, nanoparticles functionalized with high affinity targeting ligands may lead to undesired off-target binding to healthy cells. In this work, Monte Carlo simulations were used to quantitatively determine net surface interactions, binding valency, and selectivity between targeted nanoparticles and cell surfaces. Dissociation constant, KD, and target membrane protein density, ρR, are explored over a range representative of healthy and cancerous cell surfaces. Our findings show highly selective binding to diseased cell surfaces can be achieved with multiple, weaker affinity targeting ligands that can be further optimized by varying the targeting ligand density, ρL. Using the approach developed in this work, nanomedicines can be optimally designed for exclusively targeting diseased cells and tissues.Ligand-functionalized nanoparticles capable of selectively binding to diseased versus healthy cell populations are attractive for improved efficacy of nanoparticle-based drug and gene therapies. However, nanoparticles functionalized with high affinity targeting ligands may lead to undesired off-target binding to healthy cells. In this work, Monte Carlo simulations were used to quantitatively determine net surface interactions, binding valency, and selectivity between targeted nanoparticles and cell surfaces. Dissociation constant, KD, and target membrane protein density, ρR, are explored over a range representative of healthy and cancerous cell surfaces. Our findings show highly selective binding to diseased cell surfaces can be achieved with multiple, weaker affinity targeting ligands that can be further optimized by varying the targeting ligand density, ρL. Using the approach developed in this work, nanomedicines can be optimally designed for exclusively targeting diseased cells and tissues. Electronic supplementary information (ESI) available: Movie showing simulation renderings of targeted (ρL = 1820/μm2, KD = 120 μM) nanoparticle selective binding to cancer (ρR = 256/μm2) vs. healthy (ρR = 64/μm2) cell surfaces. Target membrane proteins have linear color scale depending on binding energy ranging from white when unbound (URL = 0) to red when tightly bound (URL = UM). See DOI: 10.1039/c5nr03691g

Effect of Hydrofluoric Acid Etching Time on Titanium Topography, Chemistry, Wettability, and Cell Adhesion

PubMed Central

Zahran, R.; Rosales Leal, J. I.; Rodríguez Valverde, M. A.; Cabrerizo Vílchez, M. A.

2016-01-01

Titanium implant surface etching has proven an effective method to enhance cell attachment. Despite the frequent use of hydrofluoric (HF) acid, many questions remain unresolved, including the optimal etching time and its effect on surface and biological properties. The objective of this study was to investigate the effect of HF acid etching time on Ti topography, surface chemistry, wettability, and cell adhesion. These data are useful to design improved acid treatment and obtain an improved cell response. The surface topography, chemistry, dynamic wetting, and cell adhesiveness of polished Ti surfaces were evaluated after treatment with HF acid solution for 0, 2; 3, 5, 7, or 10 min, revealing a time-dependent effect of HF acid on their topography, chemistry, and wetting. Roughness and wetting increased with longer etching time except at 10 min, when roughness increased but wetness decreased. Skewness became negative after etching and kurtosis tended to 3 with longer etching time. Highest cell adhesion was achieved after 5–7 min of etching time. Wetting and cell adhesion were reduced on the highly rough surfaces obtained after 10-min etching time. PMID:27824875

Funnel for localizing biological cell placement and arrangement

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

Soscia, David; Benett, William J.; Mukerjee, Erik V.

2018-03-06

The present disclosure relates to a funnel apparatus for channeling cells onto a plurality of distinct, closely spaced regions of a seeding surface. The funnel apparatus has a body portion having an upper surface and a lower surface. The body portion forms a plurality of flow paths, at least one of which is shaped to have a decreasing cross-sectional area from the upper surface to the lower surface. The flow paths are formed at the lower surface to enable cells deposited into the flow paths at the upper surface of the funnel apparatus to be channeled into a plurality ofmore » distinct, closely spaced regions on the seeding surface positioned adjacent the lower surface.« less

Control of adhesion of human induced pluripotent stem cells to plasma-patterned polydimethylsiloxane coated with vitronectin and γ-globulin.

PubMed

Yamada, Ryotaro; Hattori, Koji; Tachikawa, Saoko; Tagaya, Motohiro; Sasaki, Toru; Sugiura, Shinji; Kanamori, Toshiyuki; Ohnuma, Kiyoshi

2014-09-01

Human induced pluripotent stem cells (hiPSCs) are a promising source of cells for medical applications. Recently, the development of polydimethylsiloxane (PDMS) microdevices to control the microenvironment of hiPSCs has been extensively studied. PDMS surfaces are often treated with low-pressure air plasma to facilitate protein adsorption and cell adhesion. However, undefined molecules present in the serum and extracellular matrix used to culture cells complicate the study of cell adhesion. Here, we studied the effects of vitronectin and γ-globulin on hiPSC adhesion to plasma-treated and untreated PDMS surfaces under defined culture conditions. We chose these proteins because they have opposite properties: vitronectin mediates hiPSC attachment to hydrophilic siliceous surfaces, whereas γ-globulin is adsorbed by hydrophobic surfaces and does not mediate cell adhesion. Immunostaining showed that, when applied separately, vitronectin and γ-globulin were adsorbed by both plasma-treated and untreated PDMS surfaces. In contrast, when PDMS surfaces were exposed to a mixture of the two proteins, vitronectin was preferentially adsorbed onto plasma-treated surfaces, whereas γ-globulin was adsorbed onto untreated surfaces. Human iPSCs adhered to the vitronectin-rich plasma-treated surfaces but not to the γ-globulin-rich untreated surfaces. On the basis of these results, we used perforated masks to prepare plasma-patterned PDMS substrates, which were then used to pattern hiPSCs. The patterned hiPSCs expressed undifferentiated-cell markers and did not escape from the patterned area for at least 7 days. The patterned PDMS could be stored for up to 6 days before hiPSCs were plated. We believe that our results will be useful for the development of hiPSC microdevices. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Laser-modified titanium surfaces enhance the osteogenic differentiation of human mesenchymal stem cells.

PubMed

Bressel, Tatiana A B; de Queiroz, Jana Dara Freires; Gomes Moreira, Susana Margarida; da Fonseca, Jéssyca T; Filho, Edson A; Guastaldi, Antônio Carlos; Batistuzzo de Medeiros, Silvia Regina

2017-11-28

Titanium surfaces have been modified by various approaches with the aim of improving the stimulation of osseointegration. Laser beam (Yb-YAG) treatment is a controllable and flexible approach to modifying surfaces. It creates a complex surface topography with micro and nano-scaled patterns, and an oxide layer that can improve the osseointegration of implants, increasing their usefulness as bone implant materials. Laser beam irradiation at various fluences (132, 210, or 235 J/cm 2 ) was used to treat commercially pure titanium discs to create complex surface topographies. The titanium discs were investigated by scanning electron microscopy, X-ray diffraction, and measurement of contact angles. The surface generated at a fluence of 235 J/cm 2 was used in the biological assays. The behavior of mesenchymal stem cells from an umbilical cord vein was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, a mineralization assay, and an alkaline phosphatase activity assay and by carrying out a quantitative real-time polymerase chain reaction for osteogenic markers. CHO-k1 cells were also exposed to titanium discs in the MTT assay. The best titanium surface was that produced by laser beam irradiation at 235 J/cm 2 fluence. Cell proliferation analysis revealed that the CHO-k1 and mesenchymal stem cells behaved differently. The laser-processed titanium surface increased the proliferation of CHO-k1 cells, reduced the proliferation of mesenchymal stem cells, upregulated the expression of the osteogenic markers, and enhanced alkaline phosphatase activity. The laser-treated titanium surface modulated cellular behavior depending on the cell type, and stimulated osteogenic differentiation. This evidence supports the potential use of laser-processed titanium surfaces as bone implant materials, and their use in regenerative medicine could promote better outcomes.

Highly Sensitive Detection of Target Biomolecules on Cell Surface Using Gold Nanoparticle Conjugated with Aptamer Probe

NASA Astrophysics Data System (ADS)

Kim, Hyonchol; Terazono, Hideyuki; Hayashi, Masahito; Takei, Hiroyuki; Yasuda, Kenji

2012-06-01

A method of gold nanoparticle (Au NP) labeling with backscattered electron (BE) imaging of field emission scanning electron microscopy (FE-SEM) was applied for specific detection of target biomolecules on a cell surface. A single-stranded DNA aptamer, which specifically binds to the target molecule on a human acute lymphoblastic leukemia cell, was conjugated with a 20 nm Au NP and used as a probe to label its target molecule on the cell. The Au NP probe was incubated with the cell, and the interaction was confirmed using BE imaging of FE-SEM through direct counting of the number of Au NPs attached on the target cell surface. Specific Au NP-aptamer probes were observed on a single cell surface and their spatial distributions including submicron-order localizations were also clearly visualized, whereas the nonspecific aptamer probes were not observed on it. The aptamer probe can be potentially dislodged from the cell surface with treatment of nucleases, indicating that Au NP-conjugated aptamer probes can be used as sensitive and reversible probes to label target biomolecules on cells.

Enhanced electrochemical nanoring electrode for analysis of cytosol in single cells.

PubMed

Zhuang, Lihong; Zuo, Huanzhen; Wu, Zengqiang; Wang, Yu; Fang, Danjun; Jiang, Dechen

2014-12-02

A microelectrode array has been applied for single cell analysis with relatively high throughput; however, the cells were typically cultured on the microelectrodes under cell-size microwell traps leading to the difficulty in the functionalization of an electrode surface for higher detection sensitivity. Here, nanoring electrodes embedded under the microwell traps were fabricated to achieve the isolation of the electrode surface and the cell support, and thus, the electrode surface can be modified to obtain enhanced electrochemical sensitivity for single cell analysis. Moreover, the nanometer-sized electrode permitted a faster diffusion of analyte to the surface for additional improvement in the sensitivity, which was evidenced by the electrochemical characterization and the simulation. To demonstrate the concept of the functionalized nanoring electrode for single cell analysis, the electrode surface was deposited with prussian blue to detect intracellular hydrogen peroxide at a single cell. Hundreds of picoamperes were observed on our functionalized nanoring electrode exhibiting the enhanced electrochemical sensitivity. The success in the achievement of a functionalized nanoring electrode will benefit the development of high throughput single cell electrochemical analysis.

Gelatin for purification and proliferation of primary keratinocyte culture for use in chronic wounds and burns.

PubMed

Rahsaz, Marjan; Geramizadeh, Bita; Kaviani, Maryam; Marzban, Saeed

2015-04-01

Human epidermal keratinocytes are currently established as a treatment for burns and wounds and have laboratory applications. Keratinocyte culture contamination by unwanted cells and inhibition of cell proliferation are barriers in primary keratinocyte culture. According to the recent literature, these cells are hard to culture. The present study was conducted to evaluate the efficacy of gelatin-coated surfaces in keratinocyte cultures. After enzymatic isolation of keratinocytes from normal epidermis by trypsin, the cells were cultured on gelatin-coated flasks in serum-free medium. Another group of cells were cultured as a control group without gelatin coating. We showed positive effects of surface coating with gelatin on the primary culture of keratinocytes. Culture of these cells on a gelatincoated surface showed better proliferation with suitable morphology. By using gelatin, adhesion of these cells to the surface was more efficient and without contamination by small round cells. Successful primary culture of keratinocytes on a gelatin-coated surface may provide better yield and optimal number of cells for research and clinical applications.

Quantitative analysis of osteoblast behavior on microgrooved hydroxyapatite and titanium substrata.

PubMed

Lu, Xiong; Leng, Yang

2003-09-01

The effects of implant surface topography and chemistry on osteoblast behavior have been a research focus because of their potential importance in orthopedic and dental applications. This work focused on the topographic effects of hydroxyapatite (HA) and titanium (Ti) surface that had identical micropatterns to determine whether there was synergistic interaction between surface chemistry and surface topography. Surface microgrooves with six different groove widths (4, 8, 16, 24, 30, and 38 microm) and three different groove depths (2, 4, and 10 microm) were made on single crystalline silicon wafers using microfabrication techniques. Ti and HA thin films were coated on the microgrooves by radio-frequency magnetron sputtering. After that, human osteoblast-like cells were seeded and cultured on the microgrooved surfaces for up to 7 days. The cells' behavior was examined using scanning electron microscopy after cells were fixed and dehydrated. Statistical analysis was based on quantitative data of orientation angle, evaluating the contact guidance, and form index, describing cell shape or cell morphology changes. The contact guidance and cell shape changes were observed on the HA and Ti microgrooves. No difference in orientation angle between HA and Ti microgrooves was found. This might suggest that surface chemistry was not a significant influence on cell guidance. However, the form index analysis indicated an interaction between topographic effects and surface chemistry. Thus, conclusions about surface topographic effects on cell behavior drawn from one type of material cannot simply be applied to another type of material. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 677-687, 2003

Modeling Surface Growth of Escherichia coli on Agar Plates

PubMed Central

Fujikawa, Hiroshi; Morozumi, Satoshi

2005-01-01

Surface growth of Escherichia coli cells on a membrane filter placed on a nutrient agar plate under various conditions was studied with a mathematical model. The surface growth of bacterial cells showed a sigmoidal curve with time on a semilogarithmic plot. To describe it, a new logistic model that we presented earlier (H. Fujikawa et al., Food Microbiol. 21:501-509, 2004) was modified. Growth curves at various constant temperatures (10 to 34°C) were successfully described with the modified model (model III). Model III gave better predictions of the rate constant of growth and the lag period than a modified Gompertz model and the Baranyi model. Using the parameter values of model III at the constant temperatures, surface growth at various temperatures was successfully predicted. Surface growth curves at various initial cell numbers were also sigmoidal and converged to the same maximum cell numbers at the stationary phase. Surface growth curves at various nutrient levels were also sigmoidal. The maximum cell number and the rate of growth were lower as the nutrient level decreased. The surface growth curve was the same as that in a liquid, except for the large curvature at the deceleration period. These curves were also well described with model III. The pattern of increase in the ATP content of cells grown on a surface was sigmoidal, similar to that for cell growth. We discovered several characteristics of the surface growth of bacterial cells under various growth conditions and examined the applicability of our model to describe these growth curves. PMID:16332768

Effect of surface viscosity, anchoring energy, and cell gap on the response time of nematic liquid crystals

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

Souza, R.F. de; Yang, D.-Ke; Lenzi, E.K.

2014-07-15

An analytical expression for the relaxation time of a nematic liquid crystal is obtained for the first time by considering the influence of surface viscosity, anchoring energy strength and cell gap, validated numerically by using the so-called relaxation method. This general equation for the molecular response time (τ{sub 0}) was derived for a vertical aligned cell and by solving an eigenvalue equation coming from the usual balance of torque equation in the Derzhanskii and Petrov formulation, recovering the usual equations in the appropriate limit. The results show that τ∼d{sup b}, where b=2 is observed only for strongly anchored cells, whilemore » for moderate to weak anchored cells, the exponent lies between 1 and 2, depending on both, surface viscosity and anchoring strength. We found that the surface viscosity is important when calculating the response time, specially for thin cells, critical for liquid crystal devices. The surface viscosity’s effect on the optical response time with pretilt is also explored. Our results bring new insights about the role of surface viscosity and its effects in applied physics. - Highlights: • The relaxation of nematic liquid crystals is calculated by taking the surface viscosity into account. • An analytical expression for the relaxation time depending on surface viscosity, anchoring strength and cell gap is obtained. • The results are numerically verified. • Surface viscosity is crucial for thin and weak anchored cells. • The effect on optical time and pretilt angle is also studied.« less

On the Interaction between Marine Boundary Layer Cellular Cloudiness and Surface Heat Fluxes

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

Kazil, J.; Feingold, G.; Wang, Hailong

2014-01-02

The interaction between marine boundary layer cellular cloudiness and surface uxes of sensible and latent heat is investigated. The investigation focuses on the non-precipitating closed-cell state and the precipitating open-cell state at low geostrophic wind speed. The Advanced Research WRF model is used to conduct cloud-system-resolving simulations with interactive surface fluxes of sensible heat, latent heat, and of sea salt aerosol, and with a detailed representation of the interaction between aerosol particles and clouds. The mechanisms responsible for the temporal evolution and spatial distribution of the surface heat fluxes in the closed- and open-cell state are investigated and explained. Itmore » is found that the horizontal spatial structure of the closed-cell state determines, by entrainment of dry free tropospheric air, the spatial distribution of surface air temperature and water vapor, and, to a lesser degree, of the surface sensible and latent heat flux. The synchronized dynamics of the the open-cell state drives oscillations in surface air temperature, water vapor, and in the surface fluxes of sensible and latent heat, and of sea salt aerosol. Open-cell cloud formation, cloud optical depth and liquid water path, and cloud and rain water path are identified as good predictors of the spatial distribution of surface air temperature and sensible heat flux, but not of surface water vapor and latent heat flux. It is shown that by enhancing the surface sensible heat flux, the open-cell state creates conditions by which it is maintained. While the open-cell state under consideration is not depleted in aerosol, and is insensitive to variations in sea-salt fluxes, it also enhances the sea-salt flux relative to the closed-cell state. In aerosol-depleted conditions, this enhancement may replenish the aerosol needed for cloud formation, and hence contribute to the perpetuation of the open-cell state as well. Spatial homogenization of the surface fluxes is found to have only a small effect on cloud properties in the investigated cases. This indicates that sub-grid scale spatial variability in the surface flux of sensible and latent heat and of sea salt aerosol may not be required in large scale and global models to describe marine boundary layer cellular cloudiness.« less

Generating Inviscid and Viscous Fluid-Flow Simulations over an Aircraft Surface Using a Fluid-Flow Mesh

NASA Technical Reports Server (NTRS)

Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)

2013-01-01

Fluid-flow simulation over a computer-generated aircraft surface is generated using inviscid and viscous simulations. A fluid-flow mesh of fluid cells is obtained. At least one inviscid fluid property for the fluid cells is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. A set of intersecting fluid cells that intersects the aircraft surface are identified. One surface mesh polygon of the surface mesh is identified for each intersecting fluid cell. A boundary-layer prediction point for each identified surface mesh polygon is determined. At least one boundary-layer fluid property for each boundary-layer prediction point is determined using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects. At least one updated fluid property for at least one fluid cell is determined using the at least one boundary-layer fluid property and the inviscid fluid simulation.

Inversion layer solar cell fabrication and evaluation

NASA Technical Reports Server (NTRS)

Call, R. L.

1972-01-01

Silicon solar cells with induced junctions were created by forming an inversion layer near the surface of the silicon by supplying a sheet of positive charge above the surface. This charged layer was supplied through three mechanisms: (1) supplying a positive potential to a transparent electrode separated from the silicon surface by a dielectric, (2) contaminating the oxide layer with positive ions, and (3) forming donor surface states that leave a positive charge on the surface. A movable semi-infinite shadow delineated the extent of sensitivity of the cell due to the inversion region. Measurements of the inversion layer cell response to light of different wavelengths indicated it to be more sensitive to the shorter wavelengths of the sun's spectrum than conventional cells. Theory of the conductance of the inversion layer vs. strength of the inversion layer was compared with experiment and found to match. Theoretical determinations of junction depth and inversion layer strength were made as a function of the surface potential for the transparent electrode cell.

Lactoperoxidase catalyzed radioiodination of cell surface immunoglobulin: incorporated radioactivity may not reflect relative cell surface Ig density. [/sup 125/I

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

Wilder, R.L.; Yuen, C.C.; Mage, R.G.

1979-02-01

Rabbit and mouse splenic lymphocytes were radioiodinated by the lactoperoxidase technique, extracted with non-ionic detergent, immunoprecipitated with high titered rabbit anti-kappa antisera, and compared by SDS-PAGE. Mouse sIg peaks were reproducibly larger in size than rabbit sIg peaks (often greater than 10 times). Neither differences in incorporation of label into the rabbit cell surface, nor differences in average sIg density explain this result. Total TCA-precipitable radioactivity was similar in each species. Estimation of the relative amounts of sIg in the mouse and rabbit showed similar average sIg densities. Differences in detergent solubility, proteolytic lability, or antisera used also do notmore » adequately account for this difference. Thus, these data indicate that radioactivity incorporated after lactoperoxidase catalyzed cell surface radioiodination may not reflect cell surface Ig density. Conclusions about cell surface density based upon relative incorporation of radioactivity should be confirmed by other approaches.« less

Inversion layer solar cell fabrication and evaluation. [measurement of response of inversion layer solar cell to light of different wavelengths

NASA Technical Reports Server (NTRS)

Call, R. L.

1973-01-01

Silicon solar cells operating with induced junctions rather than diffused junctions have been fabricated and tested. Induced junctions were created by forming an inversion layer near the surface of the silicon by supplying a sheet of positive charge above the surface. This charged layer was supplied through three mechanisms: (1) applying a positive potential to a transparent electrode separated from the silicon surface by a dielectric, (2) contaminating the oxide layer with positive ions, and (3) forming donor surface states that leave a positive charge on the surface. A movable semi-infinite shadow delineated the extent of sensitivity of the cell due to the inversion region. Measurements of the response of the inversion layer cell to light of different wavelengths indicated it to be more sensitive to the shorter wavelengths of the sun's spectrum than conventional cells. The greater sensitivity occurs because of the shallow junction and the strong electric field at the surface.

Endothelial cell behaviour on gas-plasma-treated PLA surfaces: the roles of surface chemistry and roughness.

PubMed

Shah, Amita; Shah, Sarita; Mani, Gopinath; Wenke, Joseph; Agrawal, Mauli

2011-04-01

Glow-discharge gas-plasma (GP) treatment has been shown to induce surface modifications such that cell adhesion and growth are enhanced. However, it is not known which gas used in GP treatment is optimal for endothelial cell function. Polylactic acid (PLA) films treated oxygen, argon, or nitrogen GP were characterized using contact angles, scanning electron microscopy, atomic force microscopy, optical profilometry, and x-ray photoelectron spectroscopy. All three GP treatments decreased the carbon atomic concentration and surface roughness and increased the oxygen atomic concentration. Human umbilical vein endothelial cells were cultured on the PLA films for up to 7 days. Based on proliferation and live/dead assays, surface chemistry was shown to have the greatest effect on the attachment, proliferation, and viability of these cells, while roughness did not have a significant influence. Of the different gases, endothelial cell viability, attachment and proliferation were most significantly increased on PLA surfaces treated with oxygen and argon gas plasma. Copyright © 2010 John Wiley & Sons, Ltd.

Toroidal cell and battery. [storage battery for high amp-hour load applications

NASA Technical Reports Server (NTRS)

Nagle, W. J. (Inventor)

1981-01-01

A toroidal storage battery designed to handle relatively high amp-hour loads is described. The cell includes a wound core disposed within a pair of toroidal channel shaped electrodes spaced apart by nylon insulator. The shape of the case electrodes of this toroidal cell allows a first planar doughnut shaped surface and the inner cylindrical case wall to be used as a first electrode and a second planar doughnut shaped surface and the outer cylindrical case wall to be used as a second electrode. Connectors may be used to stack two or more toroidal cells together by connecting substantially the entire surface area of the first electrode of a first cell to substantially the entire surface area of the second electrode of a second cell. The central cavity of each toroidal cell may be used as a conduit for pumping a fluid through the toroidal cell to thereby cool the cell.

Fabrication and surface modification of macroporous poly(L-lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds for human skin fibroblast cell culture.

PubMed

Yang, Jian; Shi, Guixin; Bei, Jianzhong; Wang, Shenguo; Cao, Yilin; Shang, Qingxin; Yang, Guanghui; Wang, Wenjing

2002-12-05

The fabrication and surface modification of a porous cell scaffold are very important in tissue engineering. Of most concern are high-density cell seeding, nutrient and oxygen supply, and cell affinity. In the present study, poly(L-lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds with different pore structures were fabricated. An improved method based on Archimedes' Principle for measuring the porosity of scaffolds, using a density bottle, was developed. Anhydrous ammonia plasma treatment was used to modify surface properties to improve the cell affinity of the scaffolds. The results show that hydrophilicity and surface energy were improved. The polar N-containing groups and positive charged groups also were incorporated into the sample surface. A low-temperature treatment was used to maintain the plasma-modified surface properties effectively. It would do help to the further application of plasma treatment technique. Cell culture results showed that pores smaller than 160 microm are suitable for human skin fibroblast cell growth. Cell seeding efficiency was maintained at above 99%, which is better than the efficiency achieved with the common method of prewetting by ethanol. The plasma-treatment method also helped to resolve the problem of cell loss during cell seeding, and the negative effects of the ethanol trace on cell culture were avoided. The results suggest that anhydrous ammonia plasma treatment enhances the cell affinity of porous scaffolds. Mass transport issues also have been considered. Copyright 2002 Wiley Periodicals, Inc.

A pH-sensitive heparin-binding sequence from Baculovirus gp64 protein is important for binding to mammalian cells but not to Sf9 insect cells.

PubMed

Wu, Chunxiao; Wang, Shu

2012-01-01

Binding to heparan sulfate is essential for baculovirus transduction of mammalian cells. Our previous study shows that gp64, the major glycoprotein on the virus surface, binds to heparin in a pH-dependent way, with a stronger binding at pH 6.2 than at 7.4. Using fluorescently labeled peptides, we mapped the pH-dependent heparin-binding sequence of gp64 to a 22-amino-acid region between residues 271 and 292. Binding of this region to the cell surface was also pH dependent, and peptides containing this sequence could efficiently inhibit baculovirus transduction of mammalian cells at pH 6.2. When the heparin-binding peptide was immobilized onto the bead surface to mimic the high local concentration of gp64 on the virus surface, the peptide-coated magnetic beads could efficiently pull down cells expressing heparan sulfate but not cells pretreated with heparinase or cells not expressing heparan sulfate. Interestingly, although this heparin-binding function is essential for baculovirus transduction of mammalian cells, it is dispensable for infection of Sf9 insect cells. Virus infectivity on Sf9 cells was not reduced by the presence of heparin or the identified heparin-binding peptide, even though the peptide could bind to Sf9 cell surface and be efficiently internalized. Thus, our data suggest that, depending on the availability of the target molecules on the cell surface, baculoviruses can use two different methods, electrostatic interaction with heparan sulfate and more specific receptor binding, for cell attachment.

In vitro study on bone formation and surface topography from the standpoint of biomechanics.

PubMed

Kawahara, H; Soeda, Y; Niwa, K; Takahashi, M; Kawahara, D; Araki, N

2004-12-01

Effect of surface topography upon cell-adhesion, -orientation and -differentiation was investigated by in vitro study on cellular responses to titanium substratum with different surface roughness. Cell-shape, -function and -differentiation depending upon the surface topography were clarified by use of bone formative group cells (BFGCs) derived from bone marrow of beagle's femur. BFGCs consisted of hematopoietic stem cells (HSC) and osteogenetic stem cells (OSC). Cell differentiation of BFGCs was expressed and promoted by structural changes of cytoskeleton, and cell-organella, which was caused by mechanical stress with cytoplasmic stretching of cell adhesions to the substratum. Phagocytic monocytes of HSC differentiated to osteomediator cells (OMC) by cytoplasmic stretching with cell adhesion to the substratum. The OMC mediated and promoted cell differentiation from OSC to osteoblast through osteoblastic phenotype cell (OBC) by cell-aggregation of nodules with "pile up" phenomenon of OBC onto OMC. The osteogenesis might be performed by coupling work of both cells, OMC originated from monocyte of HSC and OBC originated from OSC, which were explained by SEM, TEM and fluorescent probe investigation on BFGCs on the test plate of cp titanium plates with different topographies. This osteogenetic process was proved by investigating cell proliferation, DNA contents, cell-adhesion, alkaline phosphatase activity and osteocalcine productivity for cells on the titanium plates with different topographies. The study showed increased osteogenic effects for cells cultured on Ti with increased surface roughness. Possible mechanisms were discussed from a biomechanical perspective.

Cell Surface Changes Associated with Cellular Immune Reactions in Drosophila

NASA Astrophysics Data System (ADS)

Nappi, Anthony J.; Silvers, Michael

1984-09-01

In Drosophila melanogaster a temperature-induced change in immune competence accompanies cell surface alterations that cause its blood cells to adhere and to encapsulate a parasite. At 29 degrees C the blood cells of the tumorous-lethal (Tuml) mutant show a high degree of immune competence and encapsulate the eggs of the parasitic wasp Leptopilina heterotoma. At 21 degrees C the blood cells are essentially immune incompetent. High percentages of lectin binding cells were found under conditions which potentiated cellular encapsulation responses. Some immune reactive blood cells did not bind lectin. The low percentages of lectin binding cells in susceptible hosts suggest that developing parasites alter the cell surface of the blood cells of immune reactive hosts.

An incomplete trafficking defect to the cell-surface leads to paradoxical thrombocytosis for human and murine MPL P106L.

PubMed

Favale, Fabrizia; Messaoudi, Kahia; Varghese, Leila N; Boukour, Siham; Pecquet, Christian; Gryshkova, Vitalina; Defour, Jean Philippe; Albu, Roxana-Irina; Bluteau, Olivier; Ballerini, Paola; Leverger, Guy; Plo, Isabelle; Debili, Najet; Raslova, Hana; Favier, Remi; Constantinescu, Stefan N; Vainchenker, William

2016-12-29

The mechanisms behind the hereditary thrombocytosis induced by the thrombopoietin (THPO) receptor MPL P106L mutant remain unknown. A complete trafficking defect to the cell surface has been reported, suggesting either weak constitutive activity or nonconventional THPO-dependent mechanisms. Here, we report that the thrombocytosis phenotype induced by MPL P106L belongs to the paradoxical group, where low MPL levels on platelets and mature megakaryocytes (MKs) lead to high serum THPO levels, whereas weak but not absent MPL cell-surface localization in earlier MK progenitors allows response to THPO by signaling and amplification of the platelet lineage. MK progenitors from patients showed no spontaneous growth and responded to THPO, and MKs expressed MPL on their cell surface at low levels, whereas their platelets did not respond to THPO. Transduction of MPL P106L in CD34 + cells showed that this receptor was more efficiently localized at the cell surface on immature than on mature MKs, explaining a proliferative response to THPO of immature cells and a defect in THPO clearance in mature cells. In a retroviral mouse model performed in Mpl -/- mice, MPL P106L could induce a thrombocytosis phenotype with high circulating THPO levels. Furthermore, we could select THPO-dependent cell lines with more cell-surface MPL P106L localization that was detected by flow cytometry and [ 125 I]-THPO binding. Altogether, these results demonstrate that MPL P106L is a receptor with an incomplete defect in trafficking, which induces a low but not absent localization of the receptor on cell surface and a response to THPO in immature MK cells. © 2016 by The American Society of Hematology.

Fibrillar Structure and Charge Determine the Interaction of Polyglutamine Protein Aggregates with the Cell Surface*

PubMed Central

Trevino, R. Sean; Lauckner, Jane E.; Sourigues, Yannick; Pearce, Margaret M.; Bousset, Luc; Melki, Ronald; Kopito, Ron R.

2012-01-01

The pathogenesis of most neurodegenerative diseases, including transmissible diseases like prion encephalopathy, inherited disorders like Huntington disease, and sporadic diseases like Alzheimer and Parkinson diseases, is intimately linked to the formation of fibrillar protein aggregates. It is becoming increasingly appreciated that prion-like intercellular transmission of protein aggregates can contribute to the stereotypical spread of disease pathology within the brain, but the mechanisms underlying the binding and uptake of protein aggregates by mammalian cells are largely uninvestigated. We have investigated the properties of polyglutamine (polyQ) aggregates that endow them with the ability to bind to mammalian cells in culture and the properties of the cell surface that facilitate such uptake. Binding and internalization of polyQ aggregates are common features of mammalian cells and depend upon both trypsin-sensitive and trypsin-resistant saturable sites on the cell surface, suggesting the involvement of cell surface proteins in this process. polyQ aggregate binding depends upon the presence of a fibrillar amyloid-like structure and does not depend upon electrostatic interaction of fibrils with the cell surface. Sequences in the huntingtin protein that flank the amyloid-forming polyQ tract also influence the extent to which aggregates are able to bind to cell surfaces. PMID:22753412

Corynebacterium diphtheriae invasion-associated protein (DIP1281) is involved in cell surface organization, adhesion and internalization in epithelial cells

PubMed Central

2010-01-01

Background Corynebacterium diphtheriae, the causative agent of diphtheria, is well-investigated in respect to toxin production, while little is known about C. diphtheriae factors crucial for colonization of the host. In this study, we investigated the function of surface-associated protein DIP1281, previously annotated as hypothetical invasion-associated protein. Results Microscopic inspection of DIP1281 mutant strains revealed an increased size of the single cells in combination with an altered less club-like shape and formation of chains of cells rather than the typical V-like division forms or palisades of growing C. diphtheriae cells. Cell viability was not impaired. Immuno-fluorescence microscopy, SDS-PAGE and 2-D PAGE of surface proteins revealed clear differences of wild-type and mutant protein patterns, which were verified by atomic force microscopy. DIP1281 mutant cells were not only altered in shape and surface structure but completely lack the ability to adhere to host cells and consequently invade these. Conclusions Our data indicate that DIP1281 is predominantly involved in the organization of the outer surface protein layer rather than in the separation of the peptidoglycan cell wall of dividing bacteria. The adhesion- and invasion-negative phenotype of corresponding mutant strains is an effect of rearrangements of the outer surface. PMID:20051108

Cell Surface Expression of Biologically Active Influenza C Virus HEF Glycoprotein Expressed from cDNA

PubMed Central

Pekosz, Andrew; Lamb, Robert A.

1999-01-01

The hemagglutinin, esterase, and fusion (HEF) glycoprotein of influenza C virus possesses receptor binding, receptor destroying, and membrane fusion activities. The HEF cDNAs from influenza C/Ann Arbor/1/50 (HEF-AA) and influenza C/Taylor/1223/47 (HEF-Tay) viruses were cloned and expressed, and transport of HEF to the cell surface was monitored by susceptibility to cleavage by exogenous trypsin, indirect immunofluorescence microscopy, and flow cytometry. Previously it has been found in studies with the C/Johannesburg/1/66 strain of influenza C virus (HEF-JHB) that transport of HEF to the cell surface is severely inhibited, and it is thought that the short cytoplasmic tail, Arg-Thr-Lys, is involved in blocking HEF cell surface expression (F. Oeffner, H.-D. Klenk, and G. Herrler, J. Gen. Virol. 80:363–369, 1999). As the cytoplasmic tail amino acid sequences of HEF-AA and HEF-Tay are identical to that of HEF-JHB, the data indicate that cell surface expression of HEF-AA and HEF-Tay is not inhibited by this amino acid sequence. Furthermore, the abundant cell surface transport of HEF-AA and HEF-Tay indicates that their cell surface expression does not require coexpression of another viral protein. The HEF-AA and HEF-Tay HEF glycoproteins bound human erythrocytes, promoted membrane fusion in a low-pH and trypsin-dependent manner, and displayed esterase activity, indicating that the HEF glycoprotein alone mediates all three known functions at the cell surface. PMID:10482635

Identification of distinct topographical surface microstructures favoring either undifferentiated expansion or differentiation of murine embryonic stem cells.

PubMed

Markert, Lotte D'Andrea; Lovmand, Jette; Foss, Morten; Lauridsen, Rune Hoff; Lovmand, Michael; Füchtbauer, Ernst-Martin; Füchtbauer, Annette; Wertz, Karin; Besenbacher, Flemming; Pedersen, Finn Skou; Duch, Mogens

2009-11-01

The potential of embryonic stem (ES) cells for both self-renewal and differentiation into cells of all three germ layers has generated immense interest in utilizing these cells for tissue engineering or cell-based therapies. However, the ability to culture undifferentiated ES cells without the use of feeder cells as well as means to obtain homogeneous, differentiated cell populations devoid of residual pluripotent ES cells still remain major challenges. Here we have applied murine ES cells to topographically microstructured surface libraries, BioSurface Structure Arrays (BSSA), and investigated whether these could be used to (i) identify topographically microstructured growth supports alleviating the need for feeder cells for expansion of undifferentiated ES cells and (ii) identify specific types of microstructures enforcing differentiation of ES cells. The BSSA surfaces arrays consisted of 504 different topographical microstructures each located in a tester field of 3 x 3 mm. The murine ES cell lines CJ7 and KH2 were seeded upon the BSSA libraries and specific topographical structures facilitating either undifferentiated ES cell growth or enhancing spreading indicative of differentiation of the ES cells were identified. Secondly serial passage of undifferentiated CJ7 ES cells on selected microstructures, identified in the screening of these BSSA libraries, showed that these cells had retained germ-line potential. These results indicate that one specific type of topographical surface microstructures, identified by the BSSA technology, can substitute for feeder cells and that another subset may be used to eliminate undifferentiated ES cells from a population of differentiated ES cells.

Base-modified UDP-sugars reduce cell surface levels of P-selectin glycoprotein 1 (PSGL-1) on IL-1β-stimulated human monocytes.

PubMed

Kanabar, Varsha; Tedaldi, Lauren; Jiang, Jingqian; Nie, Xiaodan; Panina, Irina; Descroix, Karine; Man, Francis; Pitchford, Simon C; Page, Clive P; Wagner, Gerd K

2016-10-01

P-selectin glycoprotein ligand-1 (PSGL-1, CD162) is a cell-surface glycoprotein that is expressed, either constitutively or inducibly, on all myeloid and lymphoid cell lineages. PSGL-1 is implicated in cell-cell interactions between platelets, leukocytes and endothelial cells, and a key mediator of inflammatory cell recruitment and transmigration into tissues. Here, we have investigated the effects of the β-1,4-galactosyltransferase inhibitor 5-(5-formylthien-2-yl) UDP-Gal (5-FT UDP-Gal, compound 1: ) and two close derivatives on the cell surface levels of PSGL-1 on human peripheral blood mononuclear cells (hPBMCs). PSGL-1 levels were studied both under basal conditions, and upon stimulation of hPBMCs with interleukin-1β (IL-1β). Between 1 and 24 hours after IL-1β stimulation, we observed initial PSGL-1 shedding, followed by an increase in PSGL-1 levels on the cell surface, with a maximal window between IL-1β-induced and basal levels after 72 h. All three inhibitors reduce PSGL-1 levels on IL-1β-stimulated cells in a concentration-dependent manner, but show no such effect in resting cells. Compound 1: also affects the cell surface levels of adhesion molecule CD11b in IL-1β-stimulated hPBMCs, but not of glycoproteins CD14 and CCR2. This activity profile may be linked to the inhibition of global Sialyl Lewis presentation on hPBMCs by compound 1: , which we have also observed. Although this mechanistic explanation remains hypothetical at present, our results show, for the first time, that small molecules can discriminate between IL-1β-induced and basal levels of cell surface PSGL-1. These findings open new avenues for intervention with PSGL-1 presentation on the cell surface of primed hPBMCs and may have implications for anti-inflammatory drug development. © The Author 2016. Published by Oxford University Press.

A Cell-surface Phylome for African Trypanosomes

PubMed Central

Jackson, Andrew P.; Allison, Harriet C.; Barry, J. David; Field, Mark C.; Hertz-Fowler, Christiane; Berriman, Matthew

2013-01-01

The cell surface of Trypanosoma brucei, like many protistan blood parasites, is crucial for mediating host-parasite interactions and is instrumental to the initiation, maintenance and severity of infection. Previous comparisons with the related trypanosomatid parasites T. cruzi and Leishmania major suggest that the cell-surface proteome of T. brucei is largely taxon-specific. Here we compare genes predicted to encode cell surface proteins of T. brucei with those from two related African trypanosomes, T. congolense and T. vivax. We created a cell surface phylome (CSP) by estimating phylogenies for 79 gene families with putative surface functions to understand the more recent evolution of African trypanosome surface architecture. Our findings demonstrate that the transferrin receptor genes essential for bloodstream survival in T. brucei are conserved in T. congolense but absent from T. vivax and include an expanded gene family of insect stage-specific surface glycoproteins that includes many currently uncharacterized genes. We also identify species-specific features and innovations and confirm that these include most expression site-associated genes (ESAGs) in T. brucei, which are absent from T. congolense and T. vivax. The CSP presents the first global picture of the origins and dynamics of cell surface architecture in African trypanosomes, representing the principal differences in genomic repertoire between African trypanosome species and provides a basis from which to explore the developmental and pathological differences in surface architectures. All data can be accessed at: http://www.genedb.org/Page/trypanosoma_surface_phylome. PMID:23556014

Regulation of epithelial and lymphocyte cell adhesion by adenosine deaminase-CD26 interaction.

PubMed Central

Ginés, Silvia; Mariño, Marta; Mallol, Josefa; Canela, Enric I; Morimoto, Chikao; Callebaut, Christian; Hovanessian, Ara; Casadó, Vicent; Lluis, Carmen; Franco, Rafael

2002-01-01

The extra-enzymic function of cell-surface adenosine deaminase (ADA), an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes, B cells and T cells, has lately been the subject of numerous studies. Cell-surface ADA is able to transduce co-stimulatory signals in T cells via its interaction with CD26, an integral membrane protein that acts as ADA-binding protein. The aim of the present study was to explore whether ADA-CD26 interaction plays a role in the adhesion of lymphocyte cells to human epithelial cells. To meet this aim, different lymphocyte cell lines (Jurkat and CEM T) expressing endogenous, or overexpressing human, CD26 protein were tested in adhesion assays to monolayers of colon adenocarcinoma human epithelial cells, Caco-2, which express high levels of cell-surface ADA. Interestingly, the adhesion of Jurkat and CEM T cells to a monolayer of Caco-2 cells was greatly dependent on CD26. An increase by 50% in the cell-to-cell adhesion was found in cells containing higher levels of CD26. Incubation with an anti-CD26 antibody raised against the ADA-binding site or with exogenous ADA resulted in a significant reduction (50-70%) of T-cell adhesion to monolayers of epithelial cells. The role of ADA-CD26 interaction in the lymphocyte-epithelial cell adhesion appears to be mediated by CD26 molecules that are not interacting with endogenous ADA (ADA-free CD26), since SKW6.4 (B cells) that express more cell-surface ADA showed lower adhesion than T cells. Adhesion stimulated by CD26 and ADA is mediated by T cell lymphocyte function-associated antigen. A role for ADA-CD26 interaction in cell-to-cell adhesion was confirmed further in integrin activation assays. FACS analysis revealed a higher expression of activated integrins on T cell lines in the presence of increasing amounts of exogenous ADA. Taken together, these results suggest that the ADA-CD26 interaction on the cell surface has a role in lymphocyte-epithelial cell adhesion. PMID:11772392

Identification and characterization of Vibrio cholerae surface proteins by radioiodination.

PubMed Central

Richardson, K; Parker, C D

1985-01-01

Whole cells and isolated outer membrane from Vibrio cholerae (Classical, Inaba) were radiolabeled with Iodogen or Iodo-beads as catalyst. Radiolabeling of whole cells was shown to be surface specific by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis of whole cells and cell fractions. Surface-labeled whole cells regularly showed 16 distinguishable protein species, of which nine were found in radiolabeled outer membrane preparations obtained by a lithium chloride-lithium acetate procedure. Eight of these proteins were found in outer membranes prepared by sucrose density gradient centrifugation and Triton X-100 extraction of radiolabeled whole cells. The mobility of several proteins was shown to be affected by temperature, and the major protein species exposed on the cell surface was shown to consist of at least two different peptides. Images PMID:3980099

Osteoblast adhesion, migration, and proliferation variations on chemically patterned nanocrystalline diamond films evaluated by live-cell imaging.

PubMed

Broz, Antonin; Ukraintsev, Egor; Kromka, Alexander; Rezek, Bohuslav; Hubalek Kalbacova, Marie

2017-05-01

Cell fate modulation by adapting the surface of a biocompatible material is nowadays a challenge in implantology, tissue engineering as well as in construction of biosensors. Nanocrystalline diamond (NCD) thin films are considered promising in these fields due to their extraordinary physical and chemical properties and diverse ways in which they can be modified structurally and chemically. The initial cell distribution, the rate of cell adhesion, distance of cell migration and also the cell proliferation are influenced by the NCD surface termination. Here, we use real-time live-cell imaging to investigate the above-mentioned processes on oxidized NCD (NCD-O) and hydrogenated NCD (NCD-H) to elucidate cell preference to the NCD-O especially on surfaces with microscopic surface termination patterns. Cells adhere more slowly and migrate farther on NCD-H than on NCD-O. Cells seeded with a fetal bovine serum (FBS) supplement in the medium move across the surface prior to adhesion. In the absence of FBS, the cells adhere immediately, but still exhibit different migration and proliferation on NCD-O/H regions. We discuss the impact of these effects on the formation of cell arrays on micropatterned NCD. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1469-1478, 2017. © 2017 Wiley Periodicals, Inc.

Effect of Stratification on Surface Properties of Corneal Epithelial Cells

PubMed Central

Yáñez-Soto, Bernardo; Leonard, Brian C.; Raghunathan, Vijay Krishna; Abbott, Nicholas L.; Murphy, Christopher J.

2015-01-01

Purpose The purpose of this study was to determine the influence of mucin expression in an immortalized human corneal epithelial cell line (hTCEpi) on the surface properties of cells, such as wettability, contact angle, and surface heterogeneity. Methods hTCEpi cells were cultured to confluence in serum-free medium. The medium was then replaced by stratification medium to induce mucin biosynthesis. The mucin expression profile was analyzed using quantitative PCR and Western blotting. Contact angles were measured using a two-immiscible liquid method, and contact angle hysteresis was evaluated by tilting the apparatus and recording advancing and receding contact angles. The spatial distribution of mucins was evaluated with fluorescently labeled lectin. Results hTCEpi cells expressed the three main ocular mucins (MUC1, MUC4, and MUC16) with a maximum between days 1 and 3 of the stratification process. Upon stratification, cells caused a very significant increase in contact angle hysteresis, suggesting the development of spatially discrete and heterogeneously distributed surface features, defined by topography and/or chemical functionality. Although atomic force microscopy measurements showed no formation of appreciable topographic features on the surface of the cells, we observed a significant increase in surface chemical heterogeneity. Conclusions The surface chemical heterogeneity of the corneal epithelium may influence the dynamic behavior of tear film by “pinning” the contact line between the cellular surface and aqueous tear film. Engineering the surface properties of corneal epithelium could potentially lead to novel treatments in dry eye disease. PMID:26747762

Impurity concentrations and surface charge densities on the heavily doped face of a silicon solar cell

NASA Technical Reports Server (NTRS)

Weinberg, I.; Hsu, L. C.

1977-01-01

Increased solar cell efficiencies are attained by reduction of surface recombination and variation of impurity concentration profiles at the n(+) surface of silicon solar cells. Diagnostic techniques are employed to evaluate the effects of specific materials preparation methodologies on surface and near surface concentrations. It is demonstrated that the MOS C-V method, when combined with a bulk measurement technique, yields more complete concentration data than are obtainable by either method alone. Specifically, new solar cell MOS C-V measurements are combined with bulk concentrations obtained by a successive layer removal technique utilizing measurements of sheet resistivity and Hall coefficient.

Rapid spectrophotometric method for determining surface free energy of microalgal cells.

PubMed

Zhang, Xinru; Jiang, Zeyi; Li, Mengyin; Zhang, Xinxin; Wang, Ge; Chou, Aihui; Chen, Liang; Yan, Hai; Zuo, Yi Y

2014-09-02

Microalgae are one of the most promising renewable energy sources with environmental sustainability. The surface free energy of microalgal cells determines their biofouling and bioflocculation behavior and hence plays an important role in microalgae cultivation and harvesting. To date, the surface energetic properties of microalgal cells are still rarely studied. We developed a novel spectrophotometric method for directly determining the surface free energy of microalgal cells. The principles of this method are based on analyzing colloidal stability of microalgae suspensions. We have shown that this method can effectively differentiate the surface free energy of four microalgal strains, i.e., marine Chlorella sp., marine Nannochloris oculata, freshwater autotrophic Chlorella sp., and freshwater heterotrophic Chlorella sp. With advantages of high-throughput and simplicity, this new spectrophotometric method has the potential to evolve into a standard method for measuring the surface free energy of cells and abiotic particles.

Methods of conditioning direct methanol fuel cells

DOEpatents

Rice, Cynthia; Ren, Xiaoming; Gottesfeld, Shimshon

2005-11-08

Methods for conditioning the membrane electrode assembly of a direct methanol fuel cell ("DMFC") are disclosed. In a first method, an electrical current of polarity opposite to that used in a functioning direct methanol fuel cell is passed through the anode surface of the membrane electrode assembly. In a second method, methanol is supplied to an anode surface of the membrane electrode assembly, allowed to cross over the polymer electrolyte membrane of the membrane electrode assembly to a cathode surface of the membrane electrode assembly, and an electrical current of polarity opposite to that in a functioning direct methanol fuel cell is drawn through the membrane electrode assembly, wherein methanol is oxidized at the cathode surface of the membrane electrode assembly while the catalyst on the anode surface is reduced. Surface oxides on the direct methanol fuel cell anode catalyst of the membrane electrode assembly are thereby reduced.

Tailorable Surface Morphology of 3D Scaffolds by Combining Additive Manufacturing with Thermally Induced Phase Separation.

PubMed

Di Luca, Andrea; de Wijn, Joost R; van Blitterswijk, Clemens A; Camarero-Espinosa, Sandra; Moroni, Lorenzo

2017-08-01

The functionalization of biomaterials substrates used for cell culture is gearing towards an increasing control over cell activity. Although a number of biomaterials have been successfully modified by different strategies to display tailored physical and chemical surface properties, it is still challenging to step from 2D substrates to 3D scaffolds with instructive surface properties for cell culture and tissue regeneration. In this study, additive manufacturing and thermally induced phase separation are combined to create 3D scaffolds with tunable surface morphology from polymer gels. Surface features vary depending on the gel concentration, the exchanging temperature, and the nonsolvent used. When preosteoblasts (MC-3T3 cells) are cultured on these scaffolds, a significant increase in alkaline phosphatase activity is measured for submicron surface topography, suggesting a potential role on early cell differentiation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface Proteins of Gram-Positive Pathogens: Using Crystallography to Uncover Novel Features in Drug and Vaccine Candidates

NASA Astrophysics Data System (ADS)

Baker, Edward N.; Proft, Thomas; Kang, Haejoo

Proteins displayed on the cell surfaces of pathogenic organisms are the front-line troops of bacterial attack, playing critical roles in colonization, infection and virulence. Although such proteins can often be recognized from genome sequence data, through characteristic sequence motifs, their functions are often unknown. One such group of surface proteins is attached to the cell surface of Gram-positive pathogens through the action of sortase enzymes. Some of these proteins are now known to form pili: long filamentous structures that mediate attachment to human cells. Crystallographic analyses of these and other cell surface proteins have uncovered novel features in their structure, assembly and stability, including the presence of inter- and intramolecular isopeptide crosslinks. This improved understanding of structures on the bacterial cell surface offers opportunities for the development of some new drug targets and for novel approaches to vaccine design.

Mining for osteogenic surface topographies: In silico design to in vivo osseo-integration.

PubMed

Hulshof, Frits F B; Papenburg, Bernke; Vasilevich, Aliaksei; Hulsman, Marc; Zhao, Yiping; Levers, Marloes; Fekete, Natalie; de Boer, Meint; Yuan, Huipin; Singh, Shantanu; Beijer, Nick; Bray, Mark-Anthony; Logan, David J; Reinders, Marcel; Carpenter, Anne E; van Blitterswijk, Clemens; Stamatialis, Dimitrios; de Boer, Jan

2017-08-01

Stem cells respond to the physicochemical parameters of the substrate on which they grow. Quantitative material activity relationships - the relationships between substrate parameters and the phenotypes they induce - have so far poorly predicted the success of bioactive implant surfaces. In this report, we screened a library of randomly selected designed surface topographies for those inducing osteogenic differentiation of bone marrow-derived mesenchymal stem cells. Cell shape features, surface design parameters, and osteogenic marker expression were strongly correlated in vitro. Furthermore, the surfaces with the highest osteogenic potential in vitro also demonstrated their osteogenic effect in vivo: these indeed strongly enhanced bone bonding in a rabbit femur model. Our work shows that by giving stem cells specific physicochemical parameters through designed surface topographies, differentiation of these cells can be dictated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Protein-scaffold Directed Nanoscale Assembly of T Cell Ligands: Artificial Antigen Presentation with Defined Valency, Density and Ratio.

PubMed

Smith, Mason R; Tolbert, Stephanie V; Wen, Fei

2018-05-07

Tuning antigen presentation to T cells is a critical step in investigating key aspects of T cell activation. However, existing technologies have limited ability to control the spatial and stoichiometric organization of T cell ligands on 3D surfaces. Here, we developed an artificial antigen presentation platform based on protein-scaffold directed assembly that allows fine control over the spatial and stoichiometric organization of T cell ligands on a 3D yeast-cell surface. Using this system, we observed that the T cell activation threshold on a 3D surface is independent of peptide-major histocompatibility complex (pMHC) valency, but instead determined by the overall pMHC surface density. When intercellular adhesion molecule 1 (ICAM-1) was co-assembled with pMHC, it enhanced antigen recognition sensitivity by 6-fold. Further, T cells responded with different magnitudes to varying ratios of pMHC and ICAM-1 and exhibited a maximum response at a ratio of 15% pMHC and 85% ICAM-1, introducing an additional parameter for tuning T cell activation. This protein-scaffold directed assembly technology is readily transferrable to acellular surfaces for translational research as well as large-scale T-cell manufacturing.

Antibody neutralization of cell-surface gC1qR/HABP1/SF2-p32 prevents lamellipodia formation and tumorigenesis

PubMed Central

Kim, Beom-Chan; Hwang, Hyun-Jung; An, Hyoung-Tae; Lee, Hyun; Park, Jun-Sub; Hong, Jin; Ko, Jesang; Kim, Chungho; Lee, Jae-Seon; Ko, Young-Gyu

2016-01-01

We previously demonstrated that cell-surface gC1qR is a key regulator of lamellipodia formation and cancer metastasis. Here, we screened a monoclonal mouse antibody against gC1qR to prevent cell migration by neutralizing cell-surface gC1qR. The anti-gC1qR antibody prevented growth factor-stimulated lamellipodia formation, cell migration and focal adhesion kinase activation by inactivating receptor tyrosine kinases (RTKs) in various cancer cells such as A549, MDA-MB-231, MCF7 and HeLa cells. The antibody neutralization of cell-surface gC1qR also inhibited angiogenesis because the anti-gC1qR antibody prevented growth factor-stimulated RTK activation, lamellipodia formation, cell migration and tube formation in HUVEC. In addition, we found that A549 tumorigenesis was reduced in a xenograft mouse model by following the administration of the anti-gC1qR antibody. With these data, we can conclude that the antibody neutralization of cell-surface gC1qR could be a good therapeutic strategy for cancer treatment. PMID:27363031

Stabilizing platinum in phosphoric acid fuel cells

NASA Technical Reports Server (NTRS)

Remick, R. J.

1982-01-01

Platinum sintering on phosphoric acid fuel cell cathodes is discussed. The cathode of the phosphoric acid fuel cell uses a high surface area platinum catalyst dispersed on a conductive carbon support to minimize both cathode polarization and fabrication costs. During operation, however, the active surface area of these electrodes decreases, which in turn leads to decreased cell performance. This loss of active surface area is a major factor in the degradation of fuel cell performance over time.

Chemically grafted fibronectin for use in QCM-D cell studies

PubMed Central

Sobolewski, Peter; Tomczyk, Nancy; Composto, Russell J.; Eckmann, David M.

2014-01-01

Traditionally, fibronectin has been used as a physisorbed surface coating (physFN) in cell culture experiments due to its critical role in cell adhesion. However, because the resulting layer is thick, unstable, and of unpredictable uniformity, this method of fibronectin deposition is unsuitable for some types of research, including quartz crystal microbalance (QCM) experiments involving cells. Here, we present a new method for chemical immobilization of fibronectin onto silicon oxide surfaces, including QCM crystals pre-coated with silicon oxide. We characterize these chemically coated fibronectin surfaces (chemFN) as well as physFN ones using surface ellipsometry (SE), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and contact angle measurements. A cell culture model demonstrates that cells on chemFN and physFN surfaces exhibit similar viability, structure, adhesion and metabolism. Finally, we perform QCM experiments using cells on both surfaces which demonstrate the superior suitability of chemFN coatings for QCM research, and provide real-time QCM-D data from cells subjected to an actin depolymerizing agent. Overall, our method of chemical immobilization of fibronectin yields great potential for furthering cellular experiments in which thin, stable and uniform coatings are desirable. As QCM research with cells has been rather limited in success thus far, we anticipate that this new technique will particularly benefit this experimental system by availing it to the much broader field of cell mechanics. PMID:24657645

Single-Molecule Light-Sheet Imaging of Suspended T Cells.

PubMed

Ponjavic, Aleks; McColl, James; Carr, Alexander R; Santos, Ana Mafalda; Kulenkampff, Klara; Lippert, Anna; Davis, Simon J; Klenerman, David; Lee, Steven F

2018-05-08

Adaptive immune responses are initiated by triggering of the T cell receptor. Single-molecule imaging based on total internal reflection fluorescence microscopy at coverslip/basal cell interfaces is commonly used to study this process. These experiments have suggested, unexpectedly, that the diffusional behavior and organization of signaling proteins and receptors may be constrained before activation. However, it is unclear to what extent the molecular behavior and cell state is affected by the imaging conditions, i.e., by the presence of a supporting surface. In this study, we implemented single-molecule light-sheet microscopy, which enables single receptors to be directly visualized at any plane in a cell to study protein dynamics and organization in live, resting T cells. The light sheet enabled the acquisition of high-quality single-molecule fluorescence images that were comparable to those of total internal reflection fluorescence microscopy. By comparing the apical and basal surfaces of surface-contacting T cells using single-molecule light-sheet microscopy, we found that most coated-glass surfaces and supported lipid bilayers profoundly affected the diffusion of membrane proteins (T cell receptor and CD45) and that all the surfaces induced calcium influx to various degrees. Our results suggest that, when studying resting T cells, surfaces are best avoided, which we achieve here by suspending cells in agarose. Copyright © 2018. Published by Elsevier Inc.

Flow-induced detachment of red blood cells adhering to surfaces by specific antigen-antibody bonds.

PubMed

Xia, Z; Goldsmith, H L; van de Ven, T G

1994-04-01

Fixed spherical swollen human red blood cells of blood type B adhering on a glass surface through antigen-antibody bonds to monoclonal mouse antihuman IgM, adsorbed or covalently linked on the surface, were detached by known hydrodynamic forces created in an impinging jet. The dynamic process of detachment of the specifically bound cells was recorded and analyzed. The fraction of adherent cells remaining on the surface decreased with increasing hydrodynamic force. For an IgM coverage of 0.26%, a tangential force on the order of 100 pN was able to detach almost all of the cells from the surface within 20 min. After a given time of exposure to hydrodynamic force, the fraction of adherent cells remaining increased with time, reflecting an increase in adhesion strength. The characteristic time for effective aging was approximately 4 h. Results from experiments in which the adsorbed antibody molecules were immobilized through covalent coupling and from evanescent wave light scattering of adherent cells, imply that deformation of red cells at the contact area was the principal cause for aging, rather than local clustering of the antibody through surface diffusion. Experiments with latex beads specifically bound to red blood cells suggest that, instead of breaking the antigen-antibody bonds, antigen molecules were extracted from the cell membrane during detachment.

Polymer microfilters with nanostructured surfaces for the culture of circulating cancer cells

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

Makarova, Olga V.; Adams, Daniel L.; Divan, Ralu

There is a critical need to improve the accuracy of drug screening and testing through the development of in vitro culture systems that more effectively mimic the in vivo environment. Surface topographical features on the nanoscale level, in short nanotopography, effect the cell growth patterns, and hence affect cell function in culture. We report the preliminary results on the fabrication, and subsequent cellular growth, of nanoscale surface topography on polymer microfilters using cell lines as a precursor to circulating tumor cells (CTCs). To create various nanoscale features on the microfilter surface, we used reactive ion etching (RIE) with and withoutmore » an etching mask. An anodized aluminum oxide (AAO) membrane fabricated directly on the polymer surface served as an etching mask. Polymer filters with a variety of modified surfaces were used to compare the effects on the culture of cancer cell lines in blank culture wells, with untreated microfilters or with RIE-treated microfilters. We then report the differences of cell shape, phenotype and growth patterns of bladder and glioblastoma cancer cell lines after isolation on the various types of material modifications. Our data suggest that RIE modified polymer filters can isolate model cell lines while retaining ell viability, and that the RIE filter modification allows T24 monolayering cells to proliferate as a structured cluster. Copyright 2016 The Authors. Published by Elsevier B.V. All rights reserved.« less

Surface characteristics of Bacillus cereus and its adhesion to stainless steel.

PubMed

Peng, J S; Tsai, W C; Chou, C C

2001-04-11

The ability of a Bacillus cereus strain, isolated from spoiled milk, to adhere to the surface of stainless steel chips was evaluated during its growth in diluted tryptic soy broth (DTSB). The number of cells that adhered to the surface increased markedly as the culture reached the end of the log phase and entered stationary phase, and continued to increase with further incubation. The surface properties of cells from the log, stationary, and late stationary phases were measured by hydrophobic interaction chromatography (HIC) and electrostatic interaction chromatography (ESIC). It was found that surface hydrophobicity of B. cereus vegetative cells from the late stationary phase was the highest followed by those from the stationary phase and the log phase cultures. While the vegetative cells prepared from stationary phase and log phase cultures, respectively, had the highest and the lowest surface charges. Adhesion of B. cereus vegetative cells to stainless steel was positively correlated with the cell surface hydrophobicity (R = 0.979). Surface hydrophobicity and surface positive charge noted on the spores harvested from diluted tryptic soy agar (DTSA) and Mn2+-tryptone glucose extract agar were higher than those harvested from the sucrose or lactose-added DTSA. A wide variation in the surface charge values was noted on the surface of various spores prepared from cultures grown on the four different media tested, while their ability to adhere to stainless steel chips in phosphate buffered saline (PBS) showed no significant difference (p > 0.05). Similarly, the number of spores or vegetative cells adhering to stainless steel suspended in PBS, milk or diluted milk (1000 x) did not differ significantly (p > 0.05).

Glycan Engineering for Cell and Developmental Biology.

PubMed

Griffin, Matthew E; Hsieh-Wilson, Linda C

2016-01-21

Cell-surface glycans are a diverse class of macromolecules that participate in many key biological processes, including cell-cell communication, development, and disease progression. Thus, the ability to modulate the structures of glycans on cell surfaces provides a powerful means not only to understand fundamental processes but also to direct activity and elicit desired cellular responses. Here, we describe methods to sculpt glycans on cell surfaces and highlight recent successes in which artificially engineered glycans have been employed to control biological outcomes such as the immune response and stem cell fate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Method of making a membrane having hydrophilic and hydrophobic surfaces for adhering cells or antibodies by using atomic oxygen or hydroxyl radicals

NASA Technical Reports Server (NTRS)

Koontz, Steven L. (Inventor); Spaulding, Glenn F. (Inventor)

1994-01-01

A portion of an organic polymer article such as a membrane is made hydrophilic by exposing a hydrophobic surface of the article to a depth of about 50 to about 5000 angstroms to atomic oxygen or hydroxyl radicals at a temperature below 100C., preferably below 40 C, to form a hydrophilic uniform surface layer of hydrophilic hydroxyl groups. The atomic oxygen and hydroxyl radicals are generated by a flowing afterglow microwave discharge, and the surface is outside of a plasma produced by the discharge. A membrane having both hydrophilic and hydrophobic surfaces can be used in an immunoassay by adhering antibodies to the hydrophobic surface. In another embodiment, the membrane is used in cell culturing where cells adhere to the hydrophilic surface. Prior to adhering cells, the hydrophilic surface may be grafted with a compatibilizing compound. A plurality of hydrophilic regions bounded by adjacent hydrophobic regions can be produced such that a maximum of one cell per each hydrophilic region adheres.

DIGE compatible labelling of surface proteins on vital cells in vitro and in vivo.

PubMed

Mayrhofer, Corina; Krieger, Sigurd; Allmaier, Günter; Kerjaschki, Dontscho

2006-01-01

Efficient methods for profiling of the cell surface proteome are desirable to get a deeper insight in basic biological processes, to localise proteins and to uncover proteins differentially expressed in diseases. Here we present a strategy to target cell surface exposed proteins via fluorescence labelling using CyDye DIGE fluors. This method has been applied to human cell lines in vitro as well as to a complex biological system in vivo. It allows detection of fluorophore-tagged cell surface proteins and visualisation of the accessible proteome within a single 2-D gel, simplifying subsequent UV MALDI-MS analysis.

Method for measuring the three-dimensional distribution of a fluorescent dye in a cell membrane

NASA Astrophysics Data System (ADS)

Yamamoto, Kazuya; Ishimaru, Ichirou; Fujii, Yoshiki; Yasokawa, Toshiki; Kuriyama, Shigeki; Masaki, Tsutomu; Takegawa, Kaoru; Tanaka, Naotaka

2007-01-01

This letter reports on a method for accurately determining the component distribution in a cell membrane over the entire cell surface. This method involves exciting a fluorescent-dyed cell membrane using evanescent light and scanning the entire cell surface by rotating the cell using a noncontact technique, namely, proximal two-beam optical tweezers. To position the cell membrane in the thin evanescent field, the authors designed an optical system capable of precisely positioning the focal position. Using this method, they were able to measure the surface distribution of glycoprotein labeled by lectin in a breast cancer cell membrane.

Proteomic Plasma Membrane Profiling Reveals an Essential Role for gp96 in the Cell Surface Expression of LDLR Family Members, Including the LDL Receptor and LRP6

PubMed Central

2012-01-01

The endoplasmic reticulum chaperone gp96 is required for the cell surface expression of a narrow range of proteins, including toll-like receptors (TLRs) and integrins. To identify a more comprehensive repertoire of proteins whose cell surface expression is dependent on gp96, we developed plasma membrane profiling (PMP), a technique that combines SILAC labeling with selective cell surface aminooxy-biotinylation. This approach allowed us to compare the relative abundance of plasma membrane (PM) proteins on gp96-deficient versus gp96-reconstituted murine pre-B cells. Analysis of unfractionated tryptic peptides initially identified 113 PM proteins, which extended to 706 PM proteins using peptide prefractionation. We confirmed a requirement for gp96 in the cell surface expression of certain TLRs and integrins and found a marked decrease in cell surface expression of four members of the extended LDL receptor family (LDLR, LRP6, Sorl1 and LRP8) in the absence of gp96. Other novel gp96 client proteins included CD180/Ly86, important in the B-cell response to lipopolysaccharide. We highlight common structural motifs in these client proteins that may be recognized by gp96, including the beta-propeller and leucine-rich repeat. This study therefore identifies the extended LDL receptor family as an important new family of proteins whose cell surface expression is regulated by gp96. PMID:22292497

Proteomic plasma membrane profiling reveals an essential role for gp96 in the cell surface expression of LDLR family members, including the LDL receptor and LRP6.

PubMed

Weekes, Michael P; Antrobus, Robin; Talbot, Suzanne; Hör, Simon; Simecek, Nikol; Smith, Duncan L; Bloor, Stuart; Randow, Felix; Lehner, Paul J

2012-03-02

The endoplasmic reticulum chaperone gp96 is required for the cell surface expression of a narrow range of proteins, including toll-like receptors (TLRs) and integrins. To identify a more comprehensive repertoire of proteins whose cell surface expression is dependent on gp96, we developed plasma membrane profiling (PMP), a technique that combines SILAC labeling with selective cell surface aminooxy-biotinylation. This approach allowed us to compare the relative abundance of plasma membrane (PM) proteins on gp96-deficient versus gp96-reconstituted murine pre-B cells. Analysis of unfractionated tryptic peptides initially identified 113 PM proteins, which extended to 706 PM proteins using peptide prefractionation. We confirmed a requirement for gp96 in the cell surface expression of certain TLRs and integrins and found a marked decrease in cell surface expression of four members of the extended LDL receptor family (LDLR, LRP6, Sorl1 and LRP8) in the absence of gp96. Other novel gp96 client proteins included CD180/Ly86, important in the B-cell response to lipopolysaccharide. We highlight common structural motifs in these client proteins that may be recognized by gp96, including the beta-propeller and leucine-rich repeat. This study therefore identifies the extended LDL receptor family as an important new family of proteins whose cell surface expression is regulated by gp96.

Identification of Proteins Associating with Glycosylphosphatidylinositol- Anchored T-Cadherin on the Surface of Vascular Endothelial Cells: Role for Grp78/BiP in T-Cadherin-Dependent Cell Survival▿ †

PubMed Central

Philippova, Maria; Ivanov, Danila; Joshi, Manjunath B.; Kyriakakis, Emmanouil; Rupp, Katharina; Afonyushkin, Taras; Bochkov, Valery; Erne, Paul; Resink, Therese J.

2008-01-01

There is scant knowledge regarding how cell surface lipid-anchored T-cadherin (T-cad) transmits signals through the plasma membrane to its intracellular targets. This study aimed to identify membrane proteins colocalizing with atypical glycosylphosphatidylinositol (GPI)-anchored T-cad on the surface of endothelial cells and to evaluate their role as signaling adaptors for T-cad. Application of coimmunoprecipitation from endothelial cells expressing c-myc-tagged T-cad and high-performance liquid chromatography revealed putative association of T-cad with the following proteins: glucose-related protein GRP78, GABA-A receptor α1 subunit, integrin β3, and two hypothetical proteins, LOC124245 and FLJ32070. Association of Grp78 and integrin β3 with T-cad on the cell surface was confirmed by surface biotinylation and reciprocal immunoprecipitation and by confocal microscopy. Use of anti-Grp78 blocking antibodies, Grp78 small interfering RNA, and coexpression of constitutively active Akt demonstrated an essential role for surface Grp78 in T-cad-dependent survival signal transduction via Akt in endothelial cells. The findings herein are relevant in the context of both the identification of transmembrane signaling partners for GPI-anchored T-cad as well as the demonstration of a novel mechanism whereby Grp78 can influence endothelial cell survival as a cell surface signaling receptor rather than an intracellular chaperone. PMID:18411300

In vitro bioactivity of micro metal injection moulded stainless steel with defined surface features.

PubMed

Bitar, Malak; Friederici, Vera; Imgrund, Philipp; Brose, Claudia; Bruinink, Arie

2012-05-04

Micrometre- and nanometre-scale surface structuring with ordered topography features may dramatically enhance orthopaedic implant integration. In this study we utilised a previously optimised micron metal injection moulding (µ-MIM) process to produce medical grade stainless steel surfaces bearing micrometre scale, protruding, hemispheres of controlled dimensions and spatial distribution. Additionally, the structured surfaces were characterised by the presence of submicrometre surface roughness resulting from metal grain boundary formation. Following cytocompatibility (cytotoxicity) evaluation using 3T3 mouse fibroblast cell line, the effect on primary human cell functionality was assessed focusing on cell attachment, shape and cytoskeleton conformation. In this respect, and by day 7 in culture, significant increase in focal adhesion size was associated with the microstructured surfaces compared to the planar control. The morphological conformation of the seeded cells, as revealed by fluorescence cytoskeleton labelling, also appeared to be guided in the vertical dimension between the hemisphere bodies. Quantitative evaluation of this guidance took place using live cytoplasm fluorescence labelling and image morphometry analysis utilising both, compactness and elongation shape descriptors. Significant increase in cell compactness was associated with the hemisphere arrays indicating collective increase in focused cell attachment to the hemisphere bodies across the entire cell population. Micrometre-scale hemisphere array patterns have therefore influenced cell attachment and conformation. Such influence may potentially aid in enhancing key cellular events such as, for example, neo-osteogenesis on implanted orthopaedic surfaces.

Application of the MOS-C-V technique to determine impurity concentrations and surface parameters on the diffused face of silicon solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.

1975-01-01

The feasibility of using the MOS C-V technique to obtain information regarding impurity and surface state concentrations on the diffused face of silicon solar cells with Ta2O5 coatings is studied. Results indicate that the MOS C-V technique yields useful information concerning surface parameters which contribute to the high, efficiency limiting, surface recombination velocities on the n+ surface of silicon solar cells.

Influence of carbon source on cell surface topology of Thermomonospora curvata.

PubMed Central

Hostalka, F; Moultrie, A; Stutzenberger, F

1992-01-01

The appearance of cell surface protuberances in Thermomonospora curvata correlated with cell-bound exoenzymes which could be removed by brief sonication. Mycelia grown on cellulose or xylan had numerous protuberances and retained 20 to 25% of endoglucanase and endoxylanase at cell surfaces, while those grown on pectin or starch had few protuberances and negligible bound pectinase or amylase. Images PMID:1400256

High-Throughput Lectin Microarray-Based Analysis of Live Cell Surface Glycosylation

PubMed Central

Li, Yu; Tao, Sheng-ce; Zhu, Heng; Schneck, Jonathan P.

2011-01-01

Lectins, plant-derived glycan-binding proteins, have long been used to detect glycans on cell surfaces. However, the techniques used to characterize serum or cells have largely been limited to mass spectrometry, blots, flow cytometry, and immunohistochemistry. While these lectin-based approaches are well established and they can discriminate a limited number of sugar isomers by concurrently using a limited number of lectins, they are not amenable for adaptation to a high-throughput platform. Fortunately, given the commercial availability of lectins with a variety of glycan specificities, lectins can be printed on a glass substrate in a microarray format to profile accessible cell-surface glycans. This method is an inviting alternative for analysis of a broad range of glycans in a high-throughput fashion and has been demonstrated to be a feasible method of identifying binding-accessible cell surface glycosylation on living cells. The current unit presents a lectin-based microarray approach for analyzing cell surface glycosylation in a high-throughput fashion. PMID:21400689

A theoretical analysis of the current-voltage characteristics of solar cells. [and their energy conversion efficiency

NASA Technical Reports Server (NTRS)

Dunbar, P. M.; Hauser, J. R.

1976-01-01

Various mechanisms which limit the conversion efficiency of silicon solar cells were studied. The effects of changes in solar cell geometry such as layer thickness on performance were examined. The effects of various antireflecting layers were also examined. It was found that any single film antireflecting layer results in a significant surface loss of photons. The use of surface texturing techniques or low loss antireflecting layers can enhance by several percentage points the conversion efficiency of silicon cells. The basic differences between n(+)-p-p(+) and p(+)-n-n(+) cells are treated. A significant part of the study was devoted to the importance of surface region lifetime and heavy doping effects on efficiency. Heavy doping bandgap reduction effects are enhanced by low surface layer lifetimes, and conversely, the reduction in solar cell efficiency due to low surface layer lifetime is further enhanced by heavy doping effects. A series of computer studies is reported which seeks to determine the best cell structure and doping levels for maximum efficiency.

Identification of Novel Tumor-Associated Cell Surface Sialoglycoproteins in Human Glioblastoma Tumors Using Quantitative Proteomics

PubMed Central

Autelitano, François; Loyaux, Denis; Roudières, Sébastien; Déon, Catherine; Guette, Frédérique; Fabre, Philippe; Ping, Qinggong; Wang, Su; Auvergne, Romane; Badarinarayana, Vasudeo; Smith, Michael; Guillemot, Jean-Claude; Goldman, Steven A.; Natesan, Sridaran; Ferrara, Pascual; August, Paul

2014-01-01

Glioblastoma multiform (GBM) remains clinical indication with significant “unmet medical need”. Innovative new therapy to eliminate residual tumor cells and prevent tumor recurrences is critically needed for this deadly disease. A major challenge of GBM research has been the identification of novel molecular therapeutic targets and accurate diagnostic/prognostic biomarkers. Many of the current clinical therapeutic targets of immunotoxins and ligand-directed toxins for high-grade glioma (HGG) cells are surface sialylated glycoproteins. Therefore, methods that systematically and quantitatively analyze cell surface sialoglycoproteins in human clinical tumor samples would be useful for the identification of potential diagnostic markers and therapeutic targets for malignant gliomas. In this study, we used the bioorthogonal chemical reporter strategy (BOCR) in combination with label-free quantitative mass spectrometry (LFQ-MS) to characterize and accurately quantify the individual cell surface sialoproteome in human GBM tissues, in fetal, adult human astrocytes, and in human neural progenitor cells (NPCs). We identified and quantified a total of 843 proteins, including 801 glycoproteins. Among the 843 proteins, 606 (72%) are known cell surface or secreted glycoproteins, including 156 CD-antigens, all major classes of cell surface receptor proteins, transporters, and adhesion proteins. Our findings identified several known as well as new cell surface antigens whose expression is predominantly restricted to human GBM tumors as confirmed by microarray transcription profiling, quantitative RT-PCR and immunohistochemical staining. This report presents the comprehensive identification of new biomarkers and therapeutic targets for the treatment of malignant gliomas using quantitative sialoglycoproteomics with clinically relevant, patient derived primary glioma cells. PMID:25360666

Identification of novel tumor-associated cell surface sialoglycoproteins in human glioblastoma tumors using quantitative proteomics.

PubMed

Autelitano, François; Loyaux, Denis; Roudières, Sébastien; Déon, Catherine; Guette, Frédérique; Fabre, Philippe; Ping, Qinggong; Wang, Su; Auvergne, Romane; Badarinarayana, Vasudeo; Smith, Michael; Guillemot, Jean-Claude; Goldman, Steven A; Natesan, Sridaran; Ferrara, Pascual; August, Paul

2014-01-01

Glioblastoma multiform (GBM) remains clinical indication with significant "unmet medical need". Innovative new therapy to eliminate residual tumor cells and prevent tumor recurrences is critically needed for this deadly disease. A major challenge of GBM research has been the identification of novel molecular therapeutic targets and accurate diagnostic/prognostic biomarkers. Many of the current clinical therapeutic targets of immunotoxins and ligand-directed toxins for high-grade glioma (HGG) cells are surface sialylated glycoproteins. Therefore, methods that systematically and quantitatively analyze cell surface sialoglycoproteins in human clinical tumor samples would be useful for the identification of potential diagnostic markers and therapeutic targets for malignant gliomas. In this study, we used the bioorthogonal chemical reporter strategy (BOCR) in combination with label-free quantitative mass spectrometry (LFQ-MS) to characterize and accurately quantify the individual cell surface sialoproteome in human GBM tissues, in fetal, adult human astrocytes, and in human neural progenitor cells (NPCs). We identified and quantified a total of 843 proteins, including 801 glycoproteins. Among the 843 proteins, 606 (72%) are known cell surface or secreted glycoproteins, including 156 CD-antigens, all major classes of cell surface receptor proteins, transporters, and adhesion proteins. Our findings identified several known as well as new cell surface antigens whose expression is predominantly restricted to human GBM tumors as confirmed by microarray transcription profiling, quantitative RT-PCR and immunohistochemical staining. This report presents the comprehensive identification of new biomarkers and therapeutic targets for the treatment of malignant gliomas using quantitative sialoglycoproteomics with clinically relevant, patient derived primary glioma cells.

Immuno-biosensor for Detection of CD20-Positive Cells Using Surface Plasmon Resonance.

PubMed

Shanehbandi, Dariush; Majidi, Jafar; Kazemi, Tohid; Baradaran, Behzad; Aghebati-Maleki, Leili; Fathi, Farzaneh; Ezzati Nazhad Dolatabadi, Jafar

2017-06-01

Purpose: Surface plasmon resonance (SPR) sensing confers a real-time assessment of molecular interactions between biomolecules and their ligands. This approach is highly sensitive and reproducible and could be employed to confirm the successful binding of drugs to cell surface targets. The specific affinity of monoclonal antibodies (MAb) for their target antigens is being utilized for development of immuno-sensors and therapeutic agents. CD20 is a surface protein of B lymphocytes which has been widely employed for immuno-targeting of B-cell related disorders. In the present study, binding ability of an anti-CD20 MAb to surface antigens of intact target cells was investigated by SPR technique. Methods: Two distinct strategies were used for immobilization of the anti-CD20 MAb onto gold (Au) chips. MUA (11-mercaptoundecanoic acid) and Staphylococcus aureus protein A (SpA) were the two systems used for this purpose. A suspension of CD20-positive Raji cells was injected in the analyte phase and the resulting interactions were analyzed and compared to those of MOLT-4 cell line as CD20-negative control. Results: Efficient binding of anti-CD20 MAb to the surface antigens of Raji cell line was confirmed by both immobilizing methods, whereas this MAb had not a noticeable affinity to the MOLT-4 cells. Conclusion: According to the outcomes, the investigated MAb had acceptable affinity and specificity to the target antigens on the cell surface and could be utilized for immuno-detection of CD20-positive intact cells by SPR method.

Immuno-biosensor for Detection of CD20-Positive Cells Using Surface Plasmon Resonance

PubMed Central

Shanehbandi, Dariush; Majidi, Jafar; Kazemi, Tohid; Baradaran, Behzad; Aghebati-Maleki, Leili; Fathi, Farzaneh; Ezzati Nazhad Dolatabadi, Jafar

2017-01-01

Purpose: Surface plasmon resonance (SPR) sensing confers a real-time assessment of molecular interactions between biomolecules and their ligands. This approach is highly sensitive and reproducible and could be employed to confirm the successful binding of drugs to cell surface targets. The specific affinity of monoclonal antibodies (MAb) for their target antigens is being utilized for development of immuno-sensors and therapeutic agents. CD20 is a surface protein of B lymphocytes which has been widely employed for immuno-targeting of B-cell related disorders. In the present study, binding ability of an anti-CD20 MAb to surface antigens of intact target cells was investigated by SPR technique. Methods: Two distinct strategies were used for immobilization of the anti-CD20 MAb onto gold (Au) chips. MUA (11-mercaptoundecanoic acid) and Staphylococcus aureus protein A (SpA) were the two systems used for this purpose. A suspension of CD20-positive Raji cells was injected in the analyte phase and the resulting interactions were analyzed and compared to those of MOLT-4 cell line as CD20-negative control. Results: Efficient binding of anti-CD20 MAb to the surface antigens of Raji cell line was confirmed by both immobilizing methods, whereas this MAb had not a noticeable affinity to the MOLT-4 cells. Conclusion: According to the outcomes, the investigated MAb had acceptable affinity and specificity to the target antigens on the cell surface and could be utilized for immuno-detection of CD20-positive intact cells by SPR method. PMID:28761820

Mass transfer in fuel cells. [electron microscopy of components, thermal decomposition of Teflon, water transport, and surface tension of KOH solutions

NASA Technical Reports Server (NTRS)

Walker, R. D., Jr.

1973-01-01

Results of experiments on electron microscopy of fuel cell components, thermal decomposition of Teflon by thermogravimetry, surface area and pore size distribution measurements, water transport in fuel cells, and surface tension of KOH solutions are described.

Efficient adhesion-based plasma membrane isolation for cell surface N-glycan analysis.

PubMed

Mun, Ji-Young; Lee, Kyung Jin; Seo, Hoon; Sung, Min-Sun; Cho, Yee Sook; Lee, Seung-Goo; Kwon, Ohsuk; Oh, Doo-Byoung

2013-08-06

Glycans, which decorate cell surfaces, play crucial roles in various physiological events involving cell surface recognition. Despite the importance of surface glycans, most analyses have been performed using total cells or whole membranes rather than plasma membranes due to difficulties related to isolation. In the present study, we employed an adhesion-based method for plasma membrane isolation to analyze N-glycans on cell surfaces. Cells were attached to polylysine-coated glass plates and then ruptured by hypotonic pressure. After washing to remove intracellular organelles, only a plasma membrane fraction remained attached to the plates, as confirmed by fluorescence imaging using organelle-specific probes. The plate was directly treated with trypsin to digest and detach the glycoproteins from the plasma membrane. From the resulting glycopeptides, N-glycans were released and analyzed using MALDI-TOF mass spectrometry and HPLC. When N-glycan profiles obtained by this method were compared to those by other methods, the amount of high-mannose type glycans mainly contaminated from the endoplasmic reticulum was dramatically reduced, which enabled the efficient detection of complex type glycans present on the cell surface. Moreover, this method was successfully used to analyze the increase of high-mannose glycans on the surface as induced by a mannosidase inhibitor treatment.

Targeting RAS-driven human cancer cells with antibodies to upregulated and essential cell-surface proteins.

PubMed

Martinko, Alexander J; Truillet, Charles; Julien, Olivier; Diaz, Juan E; Horlbeck, Max A; Whiteley, Gordon; Blonder, Josip; Weissman, Jonathan S; Bandyopadhyay, Sourav; Evans, Michael J; Wells, James A

2018-01-23

While there have been tremendous efforts to target oncogenic RAS signaling from inside the cell, little effort has focused on the cell-surface. Here, we used quantitative surface proteomics to reveal a signature of proteins that are upregulated on cells transformed with KRAS G12V , and driven by MAPK pathway signaling. We next generated a toolkit of recombinant antibodies to seven of these RAS-induced proteins. We found that five of these proteins are broadly distributed on cancer cell lines harboring RAS mutations. In parallel, a cell-surface CRISPRi screen identified integrin and Wnt signaling proteins as critical to RAS-transformed cells. We show that antibodies targeting CDCP1, a protein common to our proteomics and CRISPRi datasets, can be leveraged to deliver cytotoxic and immunotherapeutic payloads to RAS-transformed cancer cells and report for RAS signaling status in vivo. Taken together, this work presents a technological platform for attacking RAS from outside the cell. © 2018, Martinko et al.

CD22 is a recycling receptor that can shuttle cargo between the cell surface and endosomal compartments of B cells.

PubMed

O'Reilly, Mary K; Tian, Hua; Paulson, James C

2011-02-01

CD22 is a member of the sialic acid-binding Ig-like lectin (Siglec) family that is known to be a regulator of B cell signaling. Its B cell-specific expression makes it an attractive target for immunotoxin-mediated B cell depletion therapy for the treatment of B cell lymphomas and autoimmune diseases. Although CD22 is well documented to be an endocytic receptor, it is believed that after internalization, it is targeted for degradation. We show in this study that CD22 is instead constitutively recycled to the cell surface. We also find that glycan ligand-based cargo is released from CD22 and accumulates intracellularly as CD22 recycles between the cell surface and endosomal compartments. In contrast, Abs to CD22 do not accumulate but remain bound to CD22 and recycle to the cell surface. The results have implications for development of agents that target CD22 as an endocytic receptor for delivery of cytotoxic cargo to B cells.

Backscattered EM-wave manipulation using low cost 1-bit reflective surface at W-band

NASA Astrophysics Data System (ADS)

Taher Al-Nuaimi, Mustafa K.; Hong, Wei; He, Yejun

2018-04-01

The design of low cost 1-bit reflective (non-absorptive) surfaces for manipulation of backscattered EM-waves and radar cross section (RCS) reduction at W-band is presented in this article. The presented surface is designed based on the reflection phase cancellation principle. The unit cell used to compose the proposed surface has an obelus (division symbol of short wire and two disks above and below) like shape printed on a grounded dielectric material. Using this unit cell, surfaces that can efficiently manipulate the backscattered RCS pattern by using the proposed obelus-shaped unit cell (as ‘0’ element) and its mirrored unit cell (as ‘1’ element) in one surface with a 180°  ±  35° reflection phase difference between their reflection phases are designed. The proposed surfaces can generate various kinds of backscattered RCS patterns, such as single, three, or four lobes or even a low-level (reduced RCS) diffused reflection pattern when those two unit cells are distributed randomly across the surface aperture. For experimental characterization purposes, a 50  ×  50 mm2 surface is fabricated and measured.

Determining surface areas of marine alga cells by acid-base titration method.

PubMed

Wang, X; Ma, Y; Su, Y

1997-09-01

A new method for determining the surface area of living marine alga cells was described. The method uses acid-base titration to measure the surface acid/base amount on the surface of alga cells and uses the BET (Brunauer, Emmett, and Teller) equation to estimate the maximum surface acid/base amount, assuming that hydrous cell walls have carbohydrates or other structural compounds which can behave like surface Brönsted acid-base sites due to coordination of environmental H2O molecules. The method was applied to 18 diverse alga species (including 7 diatoms, 2 flagellates, 8 green algae and 1 red alga) maintained in seawater cultures. For the species examined, the surface areas of individual cells ranged from 2.8 x 10(-8) m2 for Nannochloropsis oculata to 690 x 10(-8) m2 for Dunaliella viridis, specific surface areas from 1,030 m2.g-1 for Dunaliella salina to 28,900 m2.g-1 for Pyramidomonas sp. Measurement accuracy was 15.2%. Preliminary studies show that the method may be more promising and accurate than light/electron microscopic measurements for coarse estimation of the surface area of living algae.

Surface structure characterization of Aspergillus fumigatus conidia mutated in the melanin synthesis pathway and their human cellular immune response.

PubMed

Bayry, Jagadeesh; Beaussart, Audrey; Dufrêne, Yves F; Sharma, Meenu; Bansal, Kushagra; Kniemeyer, Olaf; Aimanianda, Vishukumar; Brakhage, Axel A; Kaveri, Srini V; Kwon-Chung, Kyung J; Latgé, Jean-Paul; Beauvais, Anne

2014-08-01

In Aspergillus fumigatus, the conidial surface contains dihydroxynaphthalene (DHN)-melanin. Six-clustered gene products have been identified that mediate sequential catalysis of DHN-melanin biosynthesis. Melanin thus produced is known to be a virulence factor, protecting the fungus from the host defense mechanisms. In the present study, individual deletion of the genes involved in the initial three steps of melanin biosynthesis resulted in an altered conidial surface with masked surface rodlet layer, leaky cell wall allowing the deposition of proteins on the cell surface and exposing the otherwise-masked cell wall polysaccharides at the surface. Melanin as such was immunologically inert; however, deletion mutant conidia with modified surfaces could activate human dendritic cells and the subsequent cytokine production in contrast to the wild-type conidia. Cell surface defects were rectified in the conidia mutated in downstream melanin biosynthetic pathway, and maximum immune inertness was observed upon synthesis of vermelone onward. These observations suggest that although melanin as such is an immunologically inert material, it confers virulence by facilitating proper formation of the A. fumigatus conidial surface. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Manipulating mammalian cell morphologies using chemical-mechanical polished integrated circuit chips

NASA Astrophysics Data System (ADS)

Moussa, Hassan I.; Logan, Megan; Siow, Geoffrey C.; Phann, Darron L.; Rao, Zheng; Aucoin, Marc G.; Tsui, Ting Y.

2017-12-01

Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only 22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability.

Manipulating mammalian cell morphologies using chemical-mechanical polished integrated circuit chips.

PubMed

Moussa, Hassan I; Logan, Megan; Siow, Geoffrey C; Phann, Darron L; Rao, Zheng; Aucoin, Marc G; Tsui, Ting Y

2017-01-01

Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only ~22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability.

Manipulating mammalian cell morphologies using chemical-mechanical polished integrated circuit chips

PubMed Central

Moussa, Hassan I.; Logan, Megan; Siow, Geoffrey C.; Phann, Darron L.; Rao, Zheng; Aucoin, Marc G.; Tsui, Ting Y.

2017-01-01

Abstract Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only ~22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability. PMID:29152017

Systemic surfaceome profiling identifies target antigens for immune-based therapy in subtypes of advanced prostate cancer

PubMed Central

Lee, John K.; Bangayan, Nathanael J.; Chai, Timothy; Smith, Bryan A.; Pariva, Tiffany E.; Yun, Sangwon; Vashisht, Ajay; Zhang, Qingfu; Park, Jung Wook; Corey, Eva; Huang, Jiaoti; Wohlschlegel, James; Witte, Owen N.

2018-01-01

Prostate cancer is a heterogeneous disease composed of divergent molecular and histologic subtypes, including prostate adenocarcinoma (PrAd) and neuroendocrine prostate cancer (NEPC). While PrAd is the major histology in prostate cancer, NEPC can evolve from PrAd as a mechanism of treatment resistance that involves a transition from an epithelial to a neurosecretory cancer phenotype. Cell surface markers are often associated with specific cell lineages and differentiation states in normal development and cancer. Here, we show that PrAd and NEPC can be broadly discriminated by cell-surface profiles based on the analysis of prostate cancer gene expression datasets. To overcome a dependence on predictions of human cell-surface genes and an assumed correlation between mRNA levels and protein expression, we integrated transcriptomic and cell-surface proteomic data generated from a panel of prostate cancer cell lines to nominate cell-surface markers associated with these cancer subtypes. FXYD3 and CEACAM5 were validated as cell-surface antigens enriched in PrAd and NEPC, respectively. Given the lack of effective treatments for NEPC, CEACAM5 appeared to be a promising target for cell-based immunotherapy. As a proof of concept, engineered chimeric antigen receptor T cells targeting CEACAM5 induced antigen-specific cytotoxicity in NEPC cell lines. Our findings demonstrate that the surfaceomes of PrAd and NEPC reflect unique cancer differentiation states and broadly represent vulnerabilities amenable to therapeutic targeting. PMID:29686080

Mass Spectrometric Analysis of the Cell Surface N-Glycoproteome by Combining Metabolic Labeling and Click Chemistry

NASA Astrophysics Data System (ADS)

Smeekens, Johanna M.; Chen, Weixuan; Wu, Ronghu

2015-04-01

Cell surface N-glycoproteins play extraordinarily important roles in cell-cell communication, cell-matrix interactions, and cellular response to environmental cues. Global analysis is exceptionally challenging because many N-glycoproteins are present at low abundances and effective separation is difficult to achieve. Here, we have developed a novel strategy integrating metabolic labeling, copper-free click chemistry, and mass spectrometry (MS)-based proteomics methods to analyze cell surface N-glycoproteins comprehensively and site-specifically. A sugar analog containing an azido group, N-azidoacetylgalactosamine, was fed to cells to label glycoproteins. Glycoproteins with the functional group on the cell surface were then bound to dibenzocyclooctyne-sulfo-biotin via copper-free click chemistry under physiological conditions. After protein extraction and digestion, glycopeptides with the biotin tag were enriched by NeutrAvidin conjugated beads. Enriched glycopeptides were deglycosylated with peptide- N-glycosidase F in heavy-oxygen water, and in the process of glycan removal, asparagine was converted to aspartic acid and tagged with 18O for MS analysis. With this strategy, 144 unique N-glycopeptides containing 152 N-glycosylation sites were identified in 110 proteins in HEK293T cells. As expected, 95% of identified glycoproteins were membrane proteins, which were highly enriched. Many sites were located on important receptors, transporters, and cluster of differentiation proteins. The experimental results demonstrated that the current method is very effective for the comprehensive and site-specific identification of the cell surface N-glycoproteome and can be extensively applied to other cell surface protein studies.

Defining an optimal surface chemistry for pluripotent stem cell culture in 2D and 3D

NASA Astrophysics Data System (ADS)

Zonca, Michael R., Jr.

Surface chemistry is critical for growing pluripotent stem cells in an undifferentiated state. There is great potential to engineer the surface chemistry at the nanoscale level to regulate stem cell adhesion. However, the challenge is to identify the optimal surface chemistry of the substrata for ES cell attachment and maintenance. Using a high-throughput polymerization and screening platform, a chemically defined, synthetic polymer grafted coating that supports strong attachment and high expansion capacity of pluripotent stem cells has been discovered using mouse embryonic stem (ES) cells as a model system. This optimal substrate, N-[3-(Dimethylamino)propyl] methacrylamide (DMAPMA) that is grafted on 2D synthetic poly(ether sulfone) (PES) membrane, sustains the self-renewal of ES cells (up to 7 passages). DMAPMA supports cell attachment of ES cells through integrin beta1 in a RGD-independent manner and is similar to another recently reported polymer surface. Next, DMAPMA has been able to be transferred to 3D by grafting to synthetic, polymeric, PES fibrous matrices through both photo-induced and plasma-induced polymerization. These 3D modified fibers exhibited higher cell proliferation and greater expression of pluripotency markers of mouse ES cells than 2D PES membranes. Our results indicated that desirable surfaces in 2D can be scaled to 3D and that both surface chemistry and structural dimension strongly influence the growth and differentiation of pluripotent stem cells. Lastly, the feasibility of incorporating DMAPMA into a widely used natural polymer, alginate, has been tested. Novel adhesive alginate hydrogels have been successfully synthesized by either direct polymerization of DMAPMA and methacrylic acid blended with alginate, or photo-induced DMAPMA polymerization on alginate nanofibrous hydrogels. In particular, DMAPMA-coated alginate hydrogels support strong ES cell attachment, exhibiting a concentration dependency of DMAPMA. This research provides a new avenue for stem cell culture and maintenance using an optimal organic-based chemistry.

Base-modified UDP-sugars reduce cell surface levels of P-selectin glycoprotein 1 (PSGL-1) on IL-1β-stimulated human monocytes

PubMed Central

Kanabar, Varsha; Tedaldi, Lauren; Jiang, Jingqian; Nie, Xiaodan; Panina, Irina; Descroix, Karine; Man, Francis; Pitchford, Simon C; Page, Clive P; Wagner, Gerd K

2016-01-01

P-selectin glycoprotein ligand-1 (PSGL-1, CD162) is a cell-surface glycoprotein that is expressed, either constitutively or inducibly, on all myeloid and lymphoid cell lineages. PSGL-1 is implicated in cell–cell interactions between platelets, leukocytes and endothelial cells, and a key mediator of inflammatory cell recruitment and transmigration into tissues. Here, we have investigated the effects of the β-1,4-galactosyltransferase inhibitor 5-(5-formylthien-2-yl) UDP-Gal (5-FT UDP-Gal, compound 1) and two close derivatives on the cell surface levels of PSGL-1 on human peripheral blood mononuclear cells (hPBMCs). PSGL-1 levels were studied both under basal conditions, and upon stimulation of hPBMCs with interleukin-1β (IL-1β). Between 1 and 24 hours after IL-1β stimulation, we observed initial PSGL-1 shedding, followed by an increase in PSGL-1 levels on the cell surface, with a maximal window between IL-1β-induced and basal levels after 72 h. All three inhibitors reduce PSGL-1 levels on IL-1β-stimulated cells in a concentration-dependent manner, but show no such effect in resting cells. Compound 1 also affects the cell surface levels of adhesion molecule CD11b in IL-1β-stimulated hPBMCs, but not of glycoproteins CD14 and CCR2. This activity profile may be linked to the inhibition of global Sialyl Lewis presentation on hPBMCs by compound 1, which we have also observed. Although this mechanistic explanation remains hypothetical at present, our results show, for the first time, that small molecules can discriminate between IL-1β-induced and basal levels of cell surface PSGL-1. These findings open new avenues for intervention with PSGL-1 presentation on the cell surface of primed hPBMCs and may have implications for anti-inflammatory drug development. PMID:27233805

Micropattern array with gradient size (µPAGS) plastic surfaces fabricated by PDMS (polydimethylsiloxane) mold-based hot embossing technique for investigation of cell-surface interaction.

PubMed

Choi, Min Jin; Park, Ju Young; Cha, Kyoung Je; Rhie, Jong-Won; Cho, Dong-Woo; Kim, Dong Sung

2012-12-01

Recently, it was found that the variations of physical environment significantly affect cell behaviors including cell proliferation, migration and differentiation. Through a plastic surface with controlled mechanical properties such as stiffness, one can change the orientation and migration of cells in a particular direction, thereby determining cell behaviors. In this study, we demonstrate a polydimethylsiloxane (PDMS) mold-based hot embossing technique for rapid, simple and low-cost replication of polystyrene (PS) surfaces having micropatterns. The PDMS mold was fabricated by UV-photolithography followed by PDMS casting; the elastomeric properties of PDMS enabled us to obtain conformal contact of the PDMS mold to a PS surface and to create high transcription quality of micropatterns on the PS surface. Two different types of circular micropillar and microwell arrays were successfully replicated on the PS surfaces based on the suggested technique. The micropatterns were designed to have various diameters (2-150 µm), spacings (2-160 µm) and heights (1.4, 2.4, 8.2 and 14.9 µm), so as to generate the gradient of physical properties on the surface. Experimental parametric studies indicated that (1) the embossing temperature became a critical processing parameter as the aspect ratio of micropattern increased and (2) the PDMS mold-based hot embossing could successfully replicate micropatterns, even having an aspect ratio of 2.7 for micropattern diameter of 6 µm, with an optimal processing condition (embossing pressure and temperature of 0.4 MPa and 130 °C, respectively) in this study. We carried out cell experiments with adipose-derived stem cells on the replicated PS surface with the height of 1.4 µm to investigate cellular behaviors in response to the micropattern array with gradient size. Cellular experiment results showed that the micropillar-arrayed surface improved cell proliferation as compared with the microwell-arrayed surface. We could also estimate the ranges of pattern sizes having the desired effects on the cellular behaviors.

Surface Oxide Net Charge of a Titanium Alloy ; Modulation of Fibronectin-Activated Attachment and Spreading of Osteogenic Cells

PubMed Central

Rapuano, Bruce E.; MacDonald, Daniel E.

2010-01-01

In the current study, we have altered the surface oxide properties of a Ti6Al4V alloy using heat treatment or radiofrequency glow discharge (RFGD) in order to evaluate the relationship between the physico-chemical and biological properties of the alloy's surface oxide. The effects of surface pretreatments on the attachment of cells from two osteogenic cell lines (MG63 and MC3T3) and a mesenchymal stem cell line (C3H10T1/2) to fibronectin adsorbed to the alloy were measured. Both heat and RFGD pretreatments produced a several-fold increase in the number of cells that attached to fibronectin adsorbed to the alloy (0.001 and 10 nM FN) for each cell line tested. An antibody (HFN7.1) directed against the central integrin binding domain of fibronectin produced a 65-70% inhibition of cell attachment to fibronectin-coated disks, incdicating that cell attachment to the metal discs was dependent on fibronectin binding to cell integrin receptors. Both treatments also accelerated the cell spreading response manifested by extensive flattening and an increase in mean cellular area. The treatment-induced increases in the cell attachment activity of adsorbed fibronectin were correlated with previously demonstrated increases in Ti6Al4V oxide negative net surface charge at physiological pH produced by both heat and RFGD pretreatments. Since neither treatment increased the adsorption mass of fibronectin, these findings suggest that negatively charged surface oxide functional groups in Ti6Al4V can modulate fibronectin's integrin receptor activity by altering the adsorbed protein's conformation. Our results further suggest that negatively charged functional groups in the surface oxide can play a prominent role in the osseointegration of metallic implant materials. PMID:20884181

Regulated internalization of NMDA receptors drives PKD1-mediated suppression of the activity of residual cell-surface NMDA receptors.

PubMed

Fang, Xiao-Qian; Qiao, Haifa; Groveman, Bradley R; Feng, Shuang; Pflueger, Melissa; Xin, Wen-Kuan; Ali, Mohammad K; Lin, Shuang-Xiu; Xu, Jindong; Duclot, Florian; Kabbaj, Mohamed; Wang, Wei; Ding, Xin-Sheng; Santiago-Sim, Teresa; Jiang, Xing-Hong; Salter, Michael W; Yu, Xian-Min

2015-11-19

Constitutive and regulated internalization of cell surface proteins has been extensively investigated. The regulated internalization has been characterized as a principal mechanism for removing cell-surface receptors from the plasma membrane, and signaling to downstream targets of receptors. However, so far it is still not known whether the functional properties of remaining (non-internalized) receptor/channels may be regulated by internalization of the same class of receptor/channels. The N-methyl-D-aspartate receptor (NMDAR) is a principal subtype of glutamate-gated ion channel and plays key roles in neuronal plasticity and memory functions. NMDARs are well-known to undergo two types of regulated internalization - homologous and heterologous, which can be induced by high NMDA/glycine and DHPG, respectively. In the present work, we investigated effects of regulated NMDAR internalization on the activity of residual cell-surface NMDARs and neuronal functions. In electrophysiological experiments we discovered that the regulated internalization of NMDARs not only reduced the number of cell surface NMDARs but also caused an inhibition of the activity of remaining (non-internalized) surface NMDARs. In biochemical experiments we identified that this functional inhibition of remaining surface NMDARs was mediated by increased serine phosphorylation of surface NMDARs, resulting from the activation of protein kinase D1 (PKD1). Knockdown of PKD1 did not affect NMDAR internalization but prevented the phosphorylation and inhibition of remaining surface NMDARs and NMDAR-mediated synaptic functions. These data demonstrate a novel concept that regulated internalization of cell surface NMDARs not only reduces the number of NMDARs on the cell surface but also causes an inhibition of the activity of remaining surface NMDARs through intracellular signaling pathway(s). Furthermore, modulating the activity of remaining surface receptors may be an effective approach for treating receptor internalization-induced changes in neuronal functions of the CNS.

Antimicrobial design of titanium surface that kill sessile bacteria but support stem cells adhesion

NASA Astrophysics Data System (ADS)

Zhu, Chen; Bao, Ni-Rong; Chen, Shuo; Zhao, Jian-Ning

2016-12-01

Implant-related bacterial infection is one of the most severe postoperative complications in orthopedic or dental surgery. In this context, from the perspective of surface modification, increasing efforts have been made to enhance the antibacterial capability of titanium surface. In this work, a hierarchical hybrid surface architecture was firstly constructed on titanium surface by two-step strategy of acid etching and H2O2 aging. Then silver nanoparticles were firmly immobilized on the hierarchical surface by ion implantation, showing no detectable release of silver ions from surface. The designed titanium surface showed good bioactivity. More importantly, this elaborately designed titanium surface can effectively inactivate the adherent S. aureus on surface by virtue of a contact-killing mode. Meanwhile, the designed titanium surface can significantly facilitate the initial adhesion and spreading behaviors of bone marrow mesenchymal stem cells (MSCs) on titanium. The results suggested that, the elaborately designed titanium surface might own a cell-favoring ability that can help mammalian cells win the initial adhesion race against bacteria. We hope the present study can provide a new insight for the better understanding and designing of antimicrobial titanium surface, and pave the way to satisfying clinical requirements.

Deformation and relaxation of an incompressible viscoelastic body with surface viscoelasticity

NASA Astrophysics Data System (ADS)

Liu, Liping; Yu, Miao; Lin, Hao; Foty, Ramsey

2017-01-01

Measuring mechanical properties of cells or cell aggregates has proven to be an involved process due to their geometrical and structural complexity. Past measurements are based on material models that completely neglect the elasticity of either the surface membrane or the interior bulk. In this work, we consider general material models to account for both surface and bulk viscoelasticity. The boundary value problems are formulated for deformations and relaxations of a closed viscoelastic surface coupled with viscoelastic media inside and outside of the surface. The linearized surface elasticity models are derived for the constant surface tension model and the Helfrich-Canham bending model for coupling with the bulk viscoelasticity. For quasi-spherical surfaces, explicit solutions are obtained for the deformation, stress-strain and relaxation behaviors under a variety of loading conditions. These solutions can be applied to extract the intrinsic surface and bulk viscoelastic properties of biological cells or cell aggregates in the indentation, electro-deformation and relaxation experiments.

Cell-mediated fibre recruitment drives extracellular matrix mechanosensing in engineered fibrillar microenvironments

NASA Astrophysics Data System (ADS)

Baker, Brendon M.; Trappmann, Britta; Wang, William Y.; Sakar, Mahmut S.; Kim, Iris L.; Shenoy, Vivek B.; Burdick, Jason A.; Chen, Christopher S.

2015-12-01

To investigate how cells sense stiffness in settings structurally similar to native extracellular matrices, we designed a synthetic fibrous material with tunable mechanics and user-defined architecture. In contrast to flat hydrogel surfaces, these fibrous materials recapitulated cell-matrix interactions observed with collagen matrices including stellate cell morphologies, cell-mediated realignment of fibres, and bulk contraction of the material. Increasing the stiffness of flat hydrogel surfaces induced mesenchymal stem cell spreading and proliferation; however, increasing fibre stiffness instead suppressed spreading and proliferation for certain network architectures. Lower fibre stiffness permitted active cellular forces to recruit nearby fibres, dynamically increasing ligand density at the cell surface and promoting the formation of focal adhesions and related signalling. These studies demonstrate a departure from the well-described relationship between material stiffness and spreading established with hydrogel surfaces, and introduce fibre recruitment as a previously undescribed mechanism by which cells probe and respond to mechanics in fibrillar matrices.

Surface tension and modeling of cellular intercalation during zebrafish gastrulation.

PubMed

Calmelet, Colette; Sepich, Diane

2010-04-01

In this paper we discuss a model of zebrafish embryo notochord development based on the effect of surface tension of cells at the boundaries. We study the process of interaction of mesodermal cells at the boundaries due to adhesion and cortical tension, resulting in cellular intercalation. From in vivo experiments, we obtain cell outlines of time-lapse images of cell movements during zebrafish embryo development. Using Cellular Potts Model, we calculate the total surface energy of the system of cells at different time intervals at cell contacts. We analyze the variations of total energy depending on nature of cell contacts. We demonstrate that our model can be viable by calculating the total surface energy value for experimentally observed configurations of cells and showing that in our model these configurations correspond to a decrease in total energy values in both two and three dimensions.

Electrochemical Responsive Superhydrophilic Surfaces of Polythiophene Derivatives towards Cell Capture and Release.

PubMed

Hao, Yuwei; Li, Yingying; Zhang, Feilong; Cui, Haijun; Hu, Jinsong; Meng, Jingxin; Wang, Shutao

2018-03-23

Highly efficient cell capture and release with low background are urgently required for early diagnosis of diseases such as cancer. Herein, we report an electrochemical responsive superhydrophilic surface exhibiting specific cell capture and release with high yields and extremely low nonspecific adhesion. Through electrochemical deposition, 3-substituted thiophene derivatives are deposited onto indium tin oxide (ITO) nanowire arrays with 4-n-nonylbenzeneboronic acid (BA) as dopant, fabricating the electrochemical responsive superhydrophilic surfaces. The molecular recognition between sialic acids over-expressed on the cell membrane and doped BAs endows the electrochemical responsive surfaces with the ability to capture and release targeted cancer cells. By adjusting the substituent group of thiophene derivatives, the surface wettability can be readily regulated and further utilized for reducing nonspecific cell adhesion. Significantly, the released cells still maintain a high proliferation ability, which indicates that the applied potential does not significantly harm the cells. Therefore, these results may provide a new strategy to achieve advanced functions of biomedical materials, such as low nonspecific adhesion. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adhesion, Vitality and Osteogenic Differentiation Capacity of Adipose Derived Stem Cells Seeded on Nitinol Nanoparticle Coatings

PubMed Central

Strauß, Sarah; Neumeister, Anne; Barcikowski, Stephan; Kracht, Dietmar; Kuhbier, Jörn W.; Radtke, Christine; Reimers, Kerstin; Vogt, Peter M.

2013-01-01

Autologous cells can be used for a bioactivation of osteoimplants to enhance osseointegration. In this regard, adipose derived stem cells (ASCs) offer interesting perspectives in implantology because they are fast and easy to isolate. However, not all materials licensed for bone implants are equally suited for cell adhesion. Surface modifications are under investigation to promote cytocompatibility and cell growth. The presented study focused on influences of a Nitinol-nanoparticle coating on ASCs. Possible toxic effects as well as influences on the osteogenic differentiation potential of ASCs were evaluated by viability assays, scanning electron microscopy, immunofluorescence and alizarin red staining. It was previously shown that Nitinol-nanoparticles exert no cell toxic effects to ASCs either in soluble form or as surface coating. Here we could demonstrate that a Nitinol-nanoparticle surface coating enhances cell adherence and growth on Nitinol-surfaces. No negative influence on the osteogenic differentiation was observed. Nitinol-nanoparticle coatings offer new possibilities in implantology research regarding bioactivation by autologous ASCs, respectively enhancement of surface attraction to cells. PMID:23308190

Influence of physicochemical properties of laser-modified polystyrene on bovine serum albumin adsorption and rat C6 glioma cell behavior.

PubMed

Wang, Xuefeng; Ohlin, C André; Lu, Qinghua; Hu, Jun

2006-09-15

Biomaterial surface modification is an efficient way of improving cell-material interactions. In this study, sub-micrometer laser-induced periodic surface structures (LIPSS) were produced on polystyrene by laser irradiation. FT-IR analysis confirmed that this treatment also led to surface oxidation and anisotropic orientation of the produced carbonyl groups. As a consequence, the surface energy of the laser-treated polystyrene was 1.45 times that of the untreated polystyrene, as measured by contact-angle goniometry. Protein adsorption and rat C6 glioma cell behavior on the two substrates were investigated, showing that the changed physicochemical properties of laser-modified polystyrene surface led to an increase in the quantity of adsorbed bovine serum albumin and significantly affected the behavior of rat C6 glioma cells. In the early stages of cell spreading, cells explored their microenvironment using filopodium as the main sensor. Moreover, cells actively aligned themselves along the direction of LIPSS gradually and cell attachment and proliferation were significantly enhanced. 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006.

B-cell acquisition of antigen: Sensing the surface.

PubMed

Knight, Andrew M

2015-06-01

B-cell antigen receptor (BCR) recognition and acquisition of antigen by B cells is the essential first step in the generation of effective antibody responses. As B-cell-mediated antigen presentation is also believed to play a significant role in the activation of CD4(+) Th-cell responses, considerable effort has focused on clarifying the nature of antigen/BCR interactions. Following earlier descriptions of interactions of soluble antigens with the BCR, it is now clear that B cells also recognize, physically extract and present antigens that are tethered to, or integral components of, the surfaces or extracellular matrix of other cells. In this issue of the European Journal of Immunology, Zeng et al. [Eur. J. Immunol. 2015. 45: XXXX-XXXX] examine how the physical property or "stiffness" of the surface displaying antigens to B cells influences the B-cell response. This commentary reports that antigen tethered on "less stiff" surfaces induces increased B-cell activation and antibody responses. I then infer how "sensing the surface" by B cells may represent a new component of the immune system's ability to detect "damage," and how this understanding may influence approaches to clinical therapies where immune activity is either unwanted or desired. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Triiodothyronine Acutely Stimulates Glucose Transport into L6 Muscle Cells Without Increasing Surface GLUT4, GLUT1, or GLUT3

PubMed Central

Teixeira, Silvania Silva; Tamrakar, Akhilesh K.; Goulart-Silva, Francemilson; Serrano-Nascimento, Caroline; Klip, Amira

2012-01-01

Background Thyroid hormones (THs) act genomically to stimulate glucose transport by elevating glucose transporter (Slc2a) expression and glucose utilization by cells. However, nongenomic effects of THs are now emerging. Here, we assess how triiodothyronine (T3) acutely affects glucose transport and the content of GLUT4, GLUT1, and GLUT3 at the surface of muscle cells, and possible interactions between T3 and insulin action. Methods Differentiated L6 myotubes transfected with myc-tagged Slc2a4 (L6-GLUT4myc) or Slc2a1 (L6-GLUT1myc) and wild-type L6 myotubes were studied in the following conditions: control, hypothyroid (Tx), Tx plus T3, Tx plus insulin, and Tx plus insulin and T3. Results Glucose uptake and GLUT4 content at the cell surface decreased in the Tx group relative to controls. T3 treatment for 30 minutes increased glucose transport into L6-GLUT4myc cells without altering surface GLUT4 content, which increased only thereafter. The total amount of GLUT4 protein remained unchanged among the groups studied. The surface GLUT1 content of L6-GLUT1myc cells also remained unaltered after T3 treatment; however, in these cells glucose transport was not stimulated by T3. In wild-type L6 cells, although T3 treatment increased the total amount of GLUT3, it did not change the surface GLUT3 content. Moreover, within 30 minutes, T3 stimulation of glucose uptake was additive to that of insulin in L6-GLUT4myc cells. As expected, insulin elevated surface GLUT4 content and glucose uptake. However, interestingly, surface GLUT4 content remained unchanged or even dropped with T3 plus insulin. Conclusions These data reveal that T3 rapidly increases glucose uptake in L6-GLUT4myc cells, which, at least for 30 minutes, did not depend on an increment in GLUT4 at the cell surface yet potentiates insulin action. We propose that this rapid T3 effect involves activation of GLUT4 transporters at the cell surface, but cannot discount the involvement of an unknown GLUT. PMID:22663547

Artificial Niches for Stromal Stem Cells as a Potential Instrument for the Design of the Surface of Biomimetic Osteogenic Materials

NASA Astrophysics Data System (ADS)

Khlusov, I. A.; Khlusova, M. Yu.; Pichugin, V. F.; Sharkeev, Yu. P.; Legostaeva, E. V.

2014-02-01

A relationship between the topography of rough calcium phosphate surfaces having osteogenic niche-reliefs and the electrostatic potential of these surfaces as a possible instrument to control stromal stem cells has been investigated. The in vitro culture of human lung prenatal stromal cells on nanostructured/ultrafine-grained VT1.0 titanium alloy plates with bilateral rough calcium phosphate (CaP) microarc coating was used. It was established that the amplitude of the electret CaP surface potential linearly increased with increasing area of valleys (sockets), and the negative charge is formed on the socket surface. The area of alkaline phosphatase staining (the marker of osteoblast maturation and differentiation) of adherent CD34- CD44+ cells increases linearly with increasing area of artificial microterritory (socket) of the CaP surface occupied with each cell. The negative electret potential in valleys (sockets) of microarc CaP coatings can be the physical mechanism mediating the influence of the surface topography on osteogenic maturation and differentiation of cells in vitro. This mechanism can be called "niche-potential" and can be used as an instrument for biomimetic modification of smooth CaP surfaces to strengthen their integration with the bone tissue.

Enhanced human osteoblast cell adhesion and proliferation on 316 LS stainless steel by means of CO2 laser surface treatment.

PubMed

Hao, L; Lawrence, J; Phua, Y F; Chian, K S; Lim, G C; Zheng, H Y

2005-04-01

An effective and novel technique for improving the biocompatibility of a biograde 316 LS stainless steel through the application of CO(2) laser treatment to modify the surface properties of the material is described herein. Different surface properties, such as surface roughness, surface oxygen content, and surface energy for CO(2) laser-treated 316 LS stainless steel, untreated, and mechanically roughened samples were analyzed, and their effects on the wettability characteristics of the material were studied. It was found that modification of the wettability characteristics of the 316 LS stainless steel following CO(2) laser treatment was achieved. This improvement was identified as being mainly due to the change in the polar component of the surface energy. One-day cell adhesion tests showed that cells not only adhered and spread better, but also grew faster on the CO(2) laser-treated sample than on either the untreated or mechanically roughened sample. Further, compared with the untreated sample, MTT cell proliferation analysis revealed that the mechanically roughed surface resulted in a slight enhancement, and CO(2) laser treatment brought about a significant increase in cell proliferation. An increase in the wettability of the 316 LS stainless steel was observed to positively correlate with the cell proliferation. (c) 2004 Wiley Periodicals, Inc.

The Otto Aufranc Award: enhanced biocompatibility of stainless steel implants by titanium coating and microarc oxidation.

PubMed

Lim, Young Wook; Kwon, Soon Yong; Sun, Doo Hoon; Kim, Yong Sik

2011-02-01

Stainless steel is one of the most widely used biomaterials for internal fixation devices, but is not used in cementless arthroplasty implants because a stable oxide layer essential for biocompatibility cannot be formed on the surface. We applied a Ti electron beam coating, to form oxide layer on the stainless steel surface. To form a thicker oxide layer, we used a microarc oxidation process on the surface of Ti coated stainless steel. Modification of the surface using Ti electron beam coating and microarc oxidation could improve the ability of stainless steel implants to osseointegrate. The ability of cells to adhere to grit-blasted, titanium-coated, microarc-oxidated stainless steel in vitro was compared with that of two different types of surface modifications, machined and titanium-coated, and microarc-oxidated. We performed energy-dispersive x-ray spectroscopy and scanning electron microscopy investigations to assess the chemical composition and structure of the stainless steel surfaces and cell morphology. The biologic responses of an osteoblastlike cell line (SaOS-2) were examined by measuring proliferation (cell proliferation assay), differentiation (alkaline phosphatase activity), and attraction ability (cell migration assay). Cell proliferation, alkaline phosphatase activity, migration, and adhesion were increased in the grit-blasted, titanium-coated, microarc-oxidated group compared to the two other groups. Osteoblastlike cells on the grit-blasted, titanium-coated, microarc-oxidated surface were strongly adhered, and proliferated well compared to those on the other surfaces. The surface modifications we used (grit blasting, titanium coating, microarc oxidation) enhanced the biocompatibility (proliferation and migration of osteoblastlike cells) of stainless steel. This process is not unique to stainless steel; it can be applied to many metals to improve their biocompatibility, thus allowing a broad range of materials to be used for cementless implants.

Evaluation of Biofilms and the Effects of Biocides Thereon

NASA Technical Reports Server (NTRS)

Pierson, Duane L. (Inventor); Koenig, David W. (Inventor); Mishra, Saroj K. (Inventor)

2002-01-01

Biofilm formation is monitored by real-time continuous measurement. Images are formed of sessile cells on a surface and planktonic cells adjacent the surface. The attachment of cells to the surface is measured and quantitated, and sessile and planktonic cells are distinguished using image processing techniques. Single cells as well as colonies are monitored on or adjacent a variety of substrates. Flowing streams may be monitored. The effects of biocides on biofilms commonly isolated from recyclable water systems are measured.

Nanoarchitectured electrochemical cytosensors for selective detection of leukemia cells and quantitative evaluation of death receptor expression on cell surfaces.

PubMed

Zheng, Tingting; Fu, Jia-Ju; Hu, Lihui; Qiu, Fan; Hu, Minjin; Zhu, Jun-Jie; Hua, Zi-Chun; Wang, Hui

2013-06-04

The variable susceptibility to the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) treatment observed in various types of leukemia cells is related to the difference in the expression levels of death receptors, DR4 and DR5, on the cell surfaces. Quantifying the DR4/DR5 expression status on leukemia cell surfaces is of vital importance to the development of diagnostic tools to guide death receptor-based leukemia treatment. Taking the full advantages of novel nanobiotechnology, we have developed a robust electrochemical cytosensing approach toward ultrasensitive detection of leukemia cells with detection limit as low as ~40 cells and quantitative evaluation of DR4/DR5 expression on leukemia cell surfaces. The optimization of electron transfer and cell capture processes at specifically tailored nanobiointerfaces and the incorporation of multiple functions into rationally designed nanoprobes provide unique opportunities of integrating high specificity and signal amplification on one electrochemical cytosensor. The high sensitivity and selectivity of this electrochemical cytosensing approach also allows us to evaluate the dynamic alteration of DR4/DR5 expression on the surfaces of living cells in response to drug treatments. Using the TRAIL-resistant HL-60 cells and TRAIL-sensitive Jurkat cells as model cells, we have further verified that the TRAIL susceptibility of various types of leukemia cells is directly correlated to the surface expression levels of DR4/DR5. This versatile electrochemical cytosensing platform is believed to be of great clinical value for the early diagnosis of human leukemia and the evaluation of therapeutic effects on leukemia patients after radiation therapy or drug treatment.

Surface etching technologies for monocrystalline silicon wafer solar cells

NASA Astrophysics Data System (ADS)

Tang, Muzhi

With more than 200 GW of accumulated installations in 2015, photovoltaics (PV) has become an important green energy harvesting method. The PV market is dominated by solar cells made from crystalline silicon wafers. The engineering of the wafer surfaces is critical to the solar cell cost reduction and performance enhancement. Therefore, this thesis focuses on the development of surface etching technologies for monocrystalline silicon wafer solar cells. It aims to develop a more efficient alkaline texturing method and more effective surface cleaning processes. Firstly, a rapid, isopropanol alcohol free texturing method is successfully demonstrated to shorten the process time and reduce the consumption of chemicals. This method utilizes the special chemical properties of triethylamine, which can form Si-N bonds with wafer surface atoms. Secondly, a room-temperature anisotropic emitter etch-back process is developed to improve the n+ emitter passivation. Using this method, 19.0% efficient screen-printed aluminium back surface field solar cells are developed that show an efficiency gain of 0.15% (absolute) compared with conventionally made solar cells. Finally, state-of-the-art silicon surface passivation results are achieved using hydrogen plasma etching as a dry alternative to the classical hydrofluoric acid wet-chemical process. The effective native oxide removal and the hydrogenation of the silicon surface are shown to be the reasons for the excellent level of surface passivation achieved with this novel method.

Effect of Different Titanium Surfaces on Maturation of Murine Bone Marrow-Derived Dendritic Cells

NASA Astrophysics Data System (ADS)

Zheng, Xiaofei; Zhou, Fengjuan; Gu, Yifei; Duan, Xiaobo; Mo, Anchun

2017-02-01

Dendritic cells (DCs) play a pivotal role in the host response to implanted biomaterials. Osseointegration of titanium (Ti) implant is an immunological and inflammatory-driven process. However, the role of DCs in this complex process is largely unknown. This study aimed to investigate the effect of different Ti surfaces on DC maturation, and evaluate its subsequent potential on osteogenic differentiation of preosteoblasts. Murine bone marrow-derived DCs were seeded on Ti disks with different surface treatments, including pretreatment (PT), sandblasted/acid-etched (SLA) and modified SLA (modSLA) surface. Compared with DCs cultured on PT and SLA surfaces, the cells seeded on modSLA surface demonstrated a more round morphology with lower expression of CD86 and MHC-II, the DC maturation markers. Those cells also secreted high levels of anti-inflammatory cytokine IL-10 and TGF-β. Notably, addition of conditioned medium (CM) from modSLA-induced DCs significantly increased the mRNA expression of Runx2 and ALP as well as ALP activity by murine preosteoblast MC3T3-E1 cells. Our data demonstrated that Ti disks with different surfaces lead to differential DCs responses. PT and SLA surfaces induce DCs mature, while DCs seeded on modSLA-Ti surface maintain an immature phenotype and exhibit a potential of promoting osteogenic differentiation of MC3T3-E1 cells.

Skeletal stem cell and bone implant interactions are enhanced by LASER titanium modification

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

Sisti, Karin E., E-mail: karinellensisti@gmail.com; Biomaterials Group, Institute of Chemistry, São Paulo State University; Federal University of Mato Grosso do Sul

Purpose: To evaluate the osteo-regenerative potential of Titanium (Ti) modified by Light Amplification by Stimulated Emission of Radiation (LASER) beam (Yb-YAG) upon culture with human Skeletal Stem Cells (hSSCs{sup 1}). Methods: Human skeletal cell populations were isolated from the bone marrow of haematologically normal patients undergoing primary total hip replacement following appropriate consent. STRO-1{sup +} hSSC{sup 1} function was examined for 10 days across four groups using Ti discs: i) machined Ti surface group in basal media (Mb{sup 2}), ii) machined Ti surface group in osteogenic media (Mo{sup 3}), iii) LASER-modified Ti group in basal media (Lb{sup 4}) and, iv)more » LASER-modified Ti group in osteogenic media (Lo{sup 5}). Molecular analysis and qRT-PCR as well as functional analysis including biochemistry (DNA, Alkaline Phosphatase (ALP{sup 6}) specific activity), live/dead immunostaining (Cell Tracker Green (CTG{sup 7})/Ethidium Homodimer-1 (EH-1{sup 8})), and fluorescence staining (for vinculin and phalloidin) were undertaken. Inverted, confocal and Scanning Electron Microscopy (SEM) approaches were used to characterise cell adherence, proliferation, and phenotype. Results: Enhanced cell spreading and morphological rearrangement, including focal adhesions were observed following culture of hSSCs{sup 1} on LASER surfaces in both basal and osteogenic conditions. Biochemical analysis demonstrated enhanced ALP{sup 6} specific activity on the hSSCs{sup 1}-seeded on LASER-modified surface in basal culture media. Molecular analysis demonstrated enhanced ALP{sup 6} and osteopontin expression on titanium LASER treated surfaces in basal conditions. SEM, inverted microscopy and confocal laser scanning microscopy confirmed extensive proliferation and migration of human bone marrow stromal cells on all surfaces evaluated. Conclusions: LASER-modified Ti surfaces modify the behaviour of hSSCs.{sup 1} In particular, SSC{sup 1} adhesion, osteogenic gene expression, cell morphology and cytoskeleton structure were affected. The current studies show Ti LASER modification can enhance the osseointegration between Ti and skeletal cells, with important implications for orthopaedic application. - Highlights: • Bone stem cells on LASER Ti surface display enhanced cell growth and viability. • Bone stem cells on LASER Ti surface exhibit marked biocompatibility. • Human bone stem cells on LASER Ti surface exhibit altered morphology. • LASER Ti enhance osteogenic differentiation of human bone skeletal stem cells. • LASER Ti provides a unique approach to enhance osseointegration with the material.« less

Surface topography and chemistry shape cellular behavior on wide band-gap semiconductors.

PubMed

Bain, Lauren E; Collazo, Ramon; Hsu, Shu-Han; Latham, Nicole Pfiester; Manfra, Michael J; Ivanisevic, Albena

2014-06-01

The chemical stability and electrical properties of gallium nitride make it a promising material for the development of biocompatible electronics, a range of devices including biosensors as well as interfaces for probing and controlling cellular growth and signaling. To improve the interface formed between the probe material and the cell or biosystem, surface topography and chemistry can be applied to modify the ways in which the device interacts with its environment. PC12 cells are cultured on as-grown planar, unidirectionally polished, etched nanoporous and nanowire GaN surfaces with and without a physisorbed peptide sequence that promotes cell adhesion. While cells demonstrate preferential adhesion to roughened surfaces over as-grown flat surfaces, the topography of that roughness also influences the morphology of cellular adhesion and differentiation in neurotypic cells. Addition of the peptide sequence generally contributes further to cellular adhesion and promotes development of stereotypic long, thin neurite outgrowths over alternate morphologies. The dependence of cell behavior on both the topographic morphology and surface chemistry is thus demonstrated, providing further evidence for the importance of surface modification for modulating bio-inorganic interfaces. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Emphasizing the role of surface chemistry on hydrophobicity and cell adhesion behavior of polydimethylsiloxane/TiO2 nanocomposite films.

PubMed

Yousefi, Seyedeh Zahra; Tabatabaei-Panah, Pardis-Sadat; Seyfi, Javad

2018-07-01

Improving the bioinertness of materials is of great importance for developing biomedical devices that contact human tissues. The main goal of this study was to establish correlations among surface morphology, roughness and chemistry with hydrophobicity and cell adhesion in polydimethylsiloxane (PDMS) nanocomposites loaded with titanium dioxide (TiO 2 ) nanoparticles. Firstly, wettability results showed that the nanocomposite loaded with 30 wt.% of TiO 2 exhibited a superhydrophobic behavior; however, the morphology and roughness analysis proved that there was no discernible difference between the surface structures of samples loaded with 20 and 30 wt.% of nanoparticles. Both cell culture and MTT assay experiments showed that, despite the similarity between the surface structures, the sample loaded with 30 wt.% nanoparticles exhibits the greatest reduction in the cell viability (80%) as compared with the pure PDMS film. According to the X-ray photoelectron spectroscopy results, the remarkable reduction in cell viability of the superhydrophobic sample could be majorly attributed to the role of surface chemistry. The obtained results emphasize the importance of adjusting the surface properties especially surface chemistry to gain the optimum cell adhesion behavior. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhancement of endothelialisation of coronary stents by laser surface engineering.

PubMed

Li, Lin; Mirhosseini, Nazanin; Michael, Alun; Liu, Zhu; Wang, Tao

2013-11-01

Coronary stents have been widely used in the treatment of coronary heart disease. However, complications have hampered the long-term success of the device. Bare-metal stents (BMS) have a high rate of restenosis and poor endothelialisation. The drug-eluting stents (DES), although dramatically reduce restenosis, significantly prevent endothelialisation leading to late thrombosis and behave the same way as BMS after drug releasing. Rapid adhesion and growth of endothelial cells on the stent surface is a key process for early vascular healing after coronary stenting which contributes to the reduction of major complications. Surface properties manipulate cell growth and directly determine the success and life-span of the implants. However, the ideal surface properties of coronary stents are not yet fully understood. The objective of this research is to understand how surface micro/nano textures and associated material chemistry changes generated by a laser beam affect the behavior of endothelial cells on bare metal 316L stents. A high power laser beam was applied to modifying the surface properties of 316L coronary stent material and the commercial coronary stents, followed by examination of the adhesion and proliferation of human coronary endothelial cells that were growing on the surfaces. Surface properties were examined by scanning electron microscopy, contact angle measurement, and X-ray photoelectron spectroscopy. A novel surface with combined micro/nano features was created on stent material 316L and coronary stent with a specific surface chemistry. This surface gives rise to a threefold increase in the adhesion and eightfold increase in the proliferation of endothelial cells. Interestingly, such effects were only observed when the surface texture was produced in the nitrogen atmosphere suggesting the importance of the surface chemistry, including the dramatic increase of chromium nitride, for the interaction of endothelial cells with the material surface. This novel surface is also super-hydrophilic with close to zero water/cell culture fluid contact angles and low cytotoxicity. A novel surface created by laser surface-engineering with a combination of defined surface texture and surface chemistry was found beneficial for the improvement of coronary stent endothelialisation. The technology presented here could work with both DES and BMS with added benefit for the improvement of the biocompatibility of current coronary stents. © 2013 Wiley Periodicals, Inc.

Cell Adhesion on RGD-Displaying Knottins with Varying Numbers of Tryptophan Amino Acids to Tune the Affinity for Assembly on Cucurbit[8]uril Surfaces.

PubMed

Sankaran, Shrikrishnan; Cavatorta, Emanuela; Huskens, Jurriaan; Jonkheijm, Pascal

2017-09-05

Cell adhesion is studied on multivalent knottins, displaying RGD ligands with a high affinity for integrin receptors, that are assembled on CB[8]-methylviologen-modified surfaces. The multivalency in the knottins stems from the number of tryptophan amino acid moieties, between 0 and 4, that can form a heteroternary complex with cucurbit[8]uril (CB[8]) and surface-tethered methylviologen (MV 2+ ). The binding affinity of the knottins with CB[8] and MV 2+ surfaces was evaluated using surface plasmon resonance spectroscopy. Specific binding occurred, and the affinity increased with the valency of tryptophans on the knottin. Additionally, increased multilayer formation was observed, attributed to homoternary complex formation between tryptophan residues of different knottins and CB[8]. Thus, we were able to control the surface coverage of the knottins by valency and concentration. Cell experiments with mouse myoblast (C2C12) cells on the self-assembled knottin surfaces showed specific integrin recognition by the RGD-displaying knottins. Moreover, cells were observed to elongate more on the supramolecular knottin surfaces with a higher valency, and in addition, more pronounced focal adhesion formation was observed on the higher-valency knottin surfaces. We attribute this effect to the enhanced coverage and the enhanced affinity of the knottins in their interaction with the CB[8] surface. Collectively, these results are promising for the development of biomaterials including knottins via CB[8] ternary complexes for tunable interactions with cells.

Revealing the cell-material interface with nanometer resolution by FIB-SEM

PubMed Central

Santoro, Francesca; Zhao, Wenting; Joubert, Lydia-Marie; Duan, Liting; Schnitker, Jan; van de Burgt, Yoeri; Lou, Hsin-Ya; Liu, Bofei; Salleo, Alberto; Cui, Lifeng; Cui, Yi; Cui, Bianxiao

2018-01-01

The interface between cells and non-biological surfaces regulates cell attachment, chronic tissue responses, and ultimately the success of medical implants or biosensors. Clinical and laboratory studies show that topological features of the surface profoundly influences cellular responses, e.g. titanium surfaces with nano- and microtopographical structures enhance osteoblast attachment and host-implant integration as compare to smooth surface. To understand how cells and tissues respond to different topographical features, it is of critical importance to directly visualize the cell-materials interface at the relevant nanometer length scale. Here, we present a new method for in situ examination of the cell-to-material interface at any desired location, based on focused-ion beam milling and scanning electron microscopy imaging (FIB-SEM) to resolve the cell membrane-to-material interface with 10 nm resolution. By examining how cell membranes interact with topographical features such as nanoscale protrusions or invaginations, we discovered that the cell membrane readily deforms inward and wraps around protruding structures, but hardly deforms outward to contour invaginating structures. This asymmetric membrane response (inward vs. outward deformation) causes the cleft width between the cell membrane and the nanostructure surface to vary for more than an order of magnitude. Our results suggest that surface topology is a crucial consideration for the development of medical implants or biosensors whose performances are strongly influenced by the cell-to-material interface. We anticipate that the method can be used to explore the direct interaction of cells/tissue with medical devices such as metal implants in the future. PMID:28682058

SPE (tm) regenerative hydrogen/oxygen fuel cells for extraterrestrial surface and microgravity applications

NASA Technical Reports Server (NTRS)

Mcelroy, J. F.

1990-01-01

Viewgraphs on SPE regenerative hydrogen/oxygen fuel cells for extraterrestrial surface and microgravity applications are presented. Topics covered include: hydrogen-oxygen regenerative fuel cell energy storage system; electrochemical cell reactions; SPE cell voltage stability; passive water removal SPE fuel cell; fuel cell performance; SPE water electrolyzers; hydrophobic oxygen phase separator; hydrophilic/electrochemical hydrogen phase separator; and unitized regenerative fuel cell.

Surface Position, Not Signaling from Surrounding Maternal Tissues, Specifies Aleurone Epidermal Cell Fate in Maize[OA

PubMed Central

Gruis, Darren (Fred); Guo, Hena; Selinger, David; Tian, Qing; Olsen, Odd-Arne

2006-01-01

Maize (Zea mays) endosperm consists of an epidermal-like surface layer of aleurone cells, an underlying body of starchy endosperm cells, and a basal layer of transfer cells. To determine whether surrounding maternal tissues perform a role in specifying endosperm cell fates, a maize endosperm organ culture technique was established whereby the developing endosperm is completely removed from surrounding maternal tissues. Using cell type-specific fluorescence markers, we show that aleurone cell fate specification occurs exclusively in response to surface position and does not require specific, continued maternal signal input. The starchy endosperm and aleurone cell fates are freely interchangeable throughout the lifespan of the endosperm, with internalized aleurone cells converting to starchy endosperm cells and with starchy endosperm cells that become positioned at the surface converting to aleurone cells. In contrast to aleurone and starchy endosperm cells, transfer cells fail to develop in in vitro-grown endosperm, supporting earlier indications that maternal tissue interaction is required to fully differentiate this cell type. Several parameters confirm that the maize endosperm organ cultures described herein retain the main developmental features of in planta endosperm, including fidelity of aleurone mutant phenotypes, temporal and spatial control of cell type-specific fluorescent markers, specificity of cell type transcripts, and control of mitotic cell divisions. PMID:16698897

Transfer of Fas (CD95) protein from the cell surface to the surface of polystyrene beads coated with anti-Fas antibody clone CH-11

PubMed Central

Sawai, H.; Domae, N.

2010-01-01

Mouse monoclonal anti-Fas (CD95) antibody clone CH-11 has been widely used in research on apoptosis. CH-11 has the ability to bind to Fas protein on cell surface and induce apoptosis. Here, we used polystyrene beads coated with CH-11 to investigate the role of lipid rafts in Fas-mediated apoptosis in SKW6.4 cells. Unexpectedly, by treatment of the cells with CH-11-coated beads Fas protein was detached from cell surface and transferred to the surface of CH-11-coated beads. Western blot analysis showed that Fas protein containing both extracellular and intracellular domains was attached to the beads. Fas protein was not transferred from the cells to the surface of the beads coated with other anti-Fas antibodies or Fas ligand. Similar phenomenon was observed in Jurkat T cells. Furthermore, CH-11-induced apoptosis was suppressed by pretreatment with CH-11-coated beads in Jurkat cells. These results suggest that CH-11 might possess distinct properties on Fas protein compared with other anti-Fas antibodies or Fas ligand, and also suggest that caution should be needed to use polystyrene beads coated with antibodies such as CH-11. PMID:20353915

The influence of surface chemistry and topography on the contact guidance of MG63 osteoblast cells.

PubMed

Ismail, F S Magdon; Rohanizadeh, R; Atwa, S; Mason, R S; Ruys, A J; Martin, P J; Bendavid, A

2007-05-01

The purpose of the present study was to determine in vitro the effects of different surface topographies and chemistries of commercially pure titanium (cpTi) and diamond-like carbon (DLC) surfaces on osteoblast growth and attachment. Microgrooves (widths of 2, 4, 8 and 10 microm and a depth of 1.5-2 microm) were patterned onto silicon (Si) substrates using microlithography and reactive ion etching. The Si substrates were subsequently vapor coated with either cpTi or DLC coatings. All surfaces were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements. Using the MG63 Osteoblast-Like cell line, we determined cell viability, adhesion, and morphology on different substrates over a 3 day culture period. The results showed cpTi surfaces to be significantly more hydrophilic than DLC for groove sizes larger than 2 microm. Cell contact guidance was observed for all grooved samples in comparison to the unpatterned controls. The cell viability tests indicated a significantly greater cell number for 8 and 10 microm grooves on cpTi surfaces compared to other groove sizes. The cell adhesion study showed that the smaller groove sizes, as well as the unpatterned control groups, displayed better cell adhesion to the substrate.

Highly multiplexed and quantitative cell-surface protein profiling using genetically barcoded antibodies.

PubMed

Pollock, Samuel B; Hu, Amy; Mou, Yun; Martinko, Alexander J; Julien, Olivier; Hornsby, Michael; Ploder, Lynda; Adams, Jarrett J; Geng, Huimin; Müschen, Markus; Sidhu, Sachdev S; Moffat, Jason; Wells, James A

2018-03-13

Human cells express thousands of different surface proteins that can be used for cell classification, or to distinguish healthy and disease conditions. A method capable of profiling a substantial fraction of the surface proteome simultaneously and inexpensively would enable more accurate and complete classification of cell states. We present a highly multiplexed and quantitative surface proteomic method using genetically barcoded antibodies called phage-antibody next-generation sequencing (PhaNGS). Using 144 preselected antibodies displayed on filamentous phage (Fab-phage) against 44 receptor targets, we assess changes in B cell surface proteins after the development of drug resistance in a patient with acute lymphoblastic leukemia (ALL) and in adaptation to oncogene expression in a Myc-inducible Burkitt lymphoma model. We further show PhaNGS can be applied at the single-cell level. Our results reveal that a common set of proteins including FLT3, NCR3LG1, and ROR1 dominate the response to similar oncogenic perturbations in B cells. Linking high-affinity, selective, genetically encoded binders to NGS enables direct and highly multiplexed protein detection, comparable to RNA-sequencing for mRNA. PhaNGS has the potential to profile a substantial fraction of the surface proteome simultaneously and inexpensively to enable more accurate and complete classification of cell states. Copyright © 2018 the Author(s). Published by PNAS.

Nanosecond pulsed electric field induced changes in cell surface charge density.

PubMed

Dutta, Diganta; Palmer, Xavier-Lewis; Asmar, Anthony; Stacey, Michael; Qian, Shizhi

2017-09-01

This study reports that the surface charge density changes in Jurkat cells with the application of single 60 nanosecond pulse electric fields, using atomic force microscopy. Using an atomic force microscope tip and Jurkat cells on silica in a 0.01M KCl ionic concentration, we were able to measure the interfacial forces, while also predicting surface charge densities of both Jurkat cell and silica surfaces. The most important finding is that the pulsing conditions varyingly reduced the cells' surface charge density. This offers a novel way in which to examine cellular effects of pulsed electric fields that may lead to the identification of unique mechanical responses. Compared to a single low field strength NsPEF (15kV/cm) application, exposure of Jurkat cells to a single high field strength NsPEF (60kV/cm) resulted in a further reduction in charge density and major morphological changes. The structural, physical, and chemical properties of biological cells immensely influence their electrostatic force; we were able to investigate this through the use of atomic force microscopy by measuring the surface forces between the AFM's tip and the Jurkat cells under different pulsing conditions as well as the interfacial forces in ionic concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Antimicrobial copper alloy surfaces are effective against vegetative but not sporulated cells of gram-positive Bacillus subtilis.

PubMed

San, Kaungmyat; Long, Janet; Michels, Corinne A; Gadura, Nidhi

2015-10-01

This study explores the role of membrane phospholipid peroxidation in the copper alloy mediated contact killing of Bacillus subtilis, a spore-forming gram-positive bacterial species. We found that B. subtilis endospores exhibited significant resistance to copper alloy surface killing but vegetative cells were highly sensitive to copper surface exposure. Cell death and lipid peroxidation occurred in B. subtilis upon copper alloy surface exposure. In a sporulation-defective strain carrying a deletion of almost the entire SpoIIA operon, lipid peroxidation directly correlated with cell death. Moreover, killing and lipid peroxidation initiated immediately and at a constant rate upon exposure to the copper surface without the delay observed previously in E. coli. These findings support the hypothesis that membrane lipid peroxidation is the initiating event causing copper surface induced cell death of B. subtilis vegetative cells. The findings suggest that the observed differences in the kinetics of copper-induced killing compared to E. coli result from differences in cell envelop structure. As demonstrated in E. coli, DNA degradation was shown to be a secondary effect of copper exposure in a B. subtilis sporulation-defective strain. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Antimicrobial copper alloy surfaces are effective against vegetative but not sporulated cells of gram-positive Bacillus subtilis

PubMed Central

San, Kaungmyat; Long, Janet; Michels, Corinne A; Gadura, Nidhi

2015-01-01

This study explores the role of membrane phospholipid peroxidation in the copper alloy mediated contact killing of Bacillus subtilis, a spore-forming gram-positive bacterial species. We found that B. subtilis endospores exhibited significant resistance to copper alloy surface killing but vegetative cells were highly sensitive to copper surface exposure. Cell death and lipid peroxidation occurred in B. subtilis upon copper alloy surface exposure. In a sporulation-defective strain carrying a deletion of almost the entire SpoIIA operon, lipid peroxidation directly correlated with cell death. Moreover, killing and lipid peroxidation initiated immediately and at a constant rate upon exposure to the copper surface without the delay observed previously in E. coli. These findings support the hypothesis that membrane lipid peroxidation is the initiating event causing copper surface induced cell death of B. subtilis vegetative cells. The findings suggest that the observed differences in the kinetics of copper-induced killing compared to E. coli result from differences in cell envelop structure. As demonstrated in E. coli, DNA degradation was shown to be a secondary effect of copper exposure in a B. subtilis sporulation-defective strain. PMID:26185055

Accelerated cell-surface interlocking on plasma polymer-modified porous ceramics.

PubMed

Rebl, Henrike; Finke, Birgit; Schmidt, Jürgen; Mohamad, Heba S; Ihrke, Roland; Helm, Christiane A; Nebe, J Barbara

2016-12-01

Excellent osseointegration of permanent implants is crucial for the long lasting success of the implantation. To improve the osseointegrative potential, bio-inert titanium alloy surfaces (Ti6Al4V) are modified by plasma chemical oxidation (PCO®) of the titanium-oxide layer to a non-stoichiometric, amorphous calcium phosphate layer. The native titanium-oxide film measuring only a few nanometers is converted by PCO® to a thick porous calcium phosphate layer of about 10μm. In a second step the PCO surface is combined with a cell adhesive plasma-polymerized allylamine (PPAAm) nano film (5 and 50nm). Independent of the PPAAm coating homogeneity, the human osteoblast-like MG-63 cells show a remarkable increase in cell size and well-developed filopodia. Analyses of the actin cytoskeleton reveal that the cells mold to the pore shape of the PPAAm-covered PCO, thereby establishing a strong attachment to the surface. Interestingly, we could demonstrate that even though our untreated PCO shows excellent hydrophilicity, this alone is not sufficient to facilitate fast cell spreading, but the positive surface charges mediated by PPAAm. This multilayer composite material guarantees enhanced interlocking of the cells with the porous surface. Copyright © 2016 Elsevier B.V. All rights reserved.

A method to generate the surface cell layer of the 3D virtual shoot apex from apical initials.

PubMed

Kucypera, Krzysztof; Lipowczan, Marcin; Piekarska-Stachowiak, Anna; Nakielski, Jerzy

2017-01-01

The development of cell pattern in the surface cell layer of the shoot apex can be investigated in vivo by use of a time-lapse confocal images, showing naked meristem in 3D in successive times. However, how this layer is originated from apical initials and develops as a result of growth and divisions of their descendants, remains unknown. This is an open area for computer modelling. A method to generate the surface cell layer is presented on the example of the 3D paraboloidal shoot apical dome. In the used model the layer originates from three apical initials that meet at the dome summit and develops through growth and cell divisions under the isotropic surface growth, defined by the growth tensor. The cells, which are described by polyhedrons, divide anticlinally with the smallest division plane that passes depending on the used mode through the cell center, or the point found randomly near this center. The formation of the surface cell pattern is described with the attention being paid to activity of the apical initials and fates of their descendants. The computer generated surface layer that included about 350 cells required about 1200 divisions of the apical initials and their derivatives. The derivatives were arranged into three more or less equal clonal sectors composed of cellular clones at different age. Each apical initial renewed itself 7-8 times to produce the sector. In the shape and location and the cellular clones the following divisions of the initial were manifested. The application of the random factor resulted in more realistic cell pattern in comparison to the pure mode. The cell divisions were analyzed statistically on the top view. When all of the division walls were considered, their angular distribution was uniform, whereas in the distribution that was limited to apical initials only, some preferences related to their arrangement at the dome summit were observed. The realistic surface cell pattern was obtained. The present method is a useful tool to generate surface cell layer, study activity of initial cells and their derivatives, and how cell expansion and division are coordinated during growth. We expect its further application to clarify the question of a number and permanence or impermanence of initial cells, and possible relationship between their shape and oriented divisions, both on the ground of the growth tensor approach.

Bone Marrow Transplantation Results in Human Donor Blood Cells Acquiring and Displaying Mouse Recipient Class I MHC and CD45 Antigens on Their Surface

PubMed Central

Yamanaka, Nobuko; Wong, Christine J.; Gertsenstein, Marina; Casper, Robert F.; Nagy, Andras; Rogers, Ian M.

2009-01-01

Background Mouse models of human disease are invaluable for determining the differentiation ability and functional capacity of stem cells. The best example is bone marrow transplants for studies of hematopoietic stem cells. For organ studies, the interpretation of the data can be difficult as transdifferentiation, cell fusion or surface antigen transfer (trogocytosis) can be misinterpreted as differentiation. These events have not been investigated in hematopoietic stem cell transplant models. Methodology/Principal Findings In this study we investigated fusion and trogocytosis involving blood cells during bone marrow transplantation using a xenograft model. We report that using a standard SCID repopulating assay almost 100% of the human donor cells appear as hybrid blood cells containing both mouse and human surface antigens. Conclusion/Significance Hybrid cells are not the result of cell-cell fusion events but appear to be due to efficient surface antigen transfer, a process referred to as trogocytosis. Antigen transfer appears to be non-random and includes all donor cells regardless of sub-type. We also demonstrate that irradiation preconditioning enhances the frequency of hybrid cells and that trogocytosis is evident in non-blood cells in chimera mice. PMID:20046883

An investigation into the effect of surface roughness of stainless steel on human umbilical vein endothelial cell gene expression.

PubMed

McLucas, E; Moran, M T; Rochev, Y; Carroll, W M; Smith, T J

2006-01-01

The surface properties of vascular devices dictate the initial postimplantation reactions that occur and thus the efficacy of the implantation procedure. Over the last number of years, a number of different stent designs have emerged and stents are generally polished to a mirror finish during the manufacturing procedure. This study sought to investigate the effect of stainless steel surface roughness on endothelial cell gene expression using an appropriate cell culture in vitro assay system. Stainless steel discs were roughened by shot blasting or polished by mechanical polishing. The surface roughness of the treated and untreated discs was determined by atomic force microscopy (AFM). Cells were seeded on collagen type 1 gels and left to attach for 24 h. Stainless steel discs of varying roughness were then placed in contact with the cells and incubated for 24 h. RNA extractions and quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was then performed to determine the expression levels of candidate genes in the treated cells compared to suitable control cells. E-selectin and vascular cellular adhesion molecule (VCAM-1) were found to be significantly up-regulated in cells incubated with polished and roughened samples, indicating endothelial cell activation and inflammation. This study indicates that the surface roughness of stainless steel is an important surface property in the development of vascular stents.

The role of surface charge on the uptake and biocompatibility of hydroxyapatite nanoparticles with osteoblast cells

PubMed Central

Chen, Liang; Mccrate, Joseph M.; Lee, James C-M.; Li, Hao

2011-01-01

The objective of this study is to evaluate the effect of hydroxyapatite (HAP) nanoparticles with different surface charges on the cellular uptake behavior and in vitro cell viability and proliferation of MC3T3-E1 cell lines (osteoblast). The nanoparticles surface charge was varied by the surface modification with two carboxylic acids: 12-aminododecanoic acid (positive) and dodecanedioic acid (negative). The untreated HAP nanoparticles and dodecanoic acid modified HAP nanoparticles (neutral) were used as the control. X-ray diffraction (XRD) revealed that surface modifications by the three carboxylic acids did not change the crystal structure of HAP nanoparticles; Fourier transform infrared spectroscopy (FTIR) confirmed the adsorption and binding of the carboxylic acids on HAP nanoparticle surface; and zeta potential measurement confirmed that the chemicals successfully modified the surface charge of HAP nanoparticles in water based solution. Transmission electron microscopy (TEM) images showed that positively charged, negatively charged and untreated HAP nanoparticles, with similar size and shape, all penetrated into the cells and cells had more uptake of HAP nanoparticles with positive charge compared to those with negative charge, which might be attributed to the attractive or repulsive interaction between the negatively charged cell membrane and positively/negatively charged HAP nanoparticles. The neutral HAP nanoparticles could not penetrate cell membrane due to the larger size. MTT assay and LDH assay results indicated that as compared with the polystyrene control, greater cell viability and cell proliferation were measured on MC3T3-E1 cells treated with the three kinds of the HAP nanoparticles (neutral, positive, and untreated), among which positively charged HAP nanoparticles shows strongest improvement for cell viability and cell proliferation. In summary, the surface charge of HAP nanoparticles can be modified to influence the cellular uptake of HAP nanoparticles and the different uptake also influence the behavior of cells. These in-vitro results may also provide useful information for investigations of HAP nanoparticles applications in the gene delivery and intracellular drug delivery. PMID:21289408

Feedback Regulation of Intracellular Hydrostatic Pressure in Surface Cells of the Lens

PubMed Central

Gao, Junyuan; Sun, Xiurong; White, Thomas W.; Delamere, Nicholas A.; Mathias, Richard T.

2015-01-01

In wild-type lenses from various species, an intracellular hydrostatic pressure gradient goes from ∼340 mmHg in central fiber cells to 0 mmHg in surface cells. This gradient drives a center-to-surface flow of intracellular fluid. In lenses in which gap-junction coupling is increased, the central pressure is lower, whereas if gap-junction coupling is reduced, the central pressure is higher but surface pressure is always zero. Recently, we found that surface cell pressure was elevated in PTEN null lenses. This suggested disruption of a feedback control system that normally maintained zero surface cell pressure. Our purpose in this study was to investigate and characterize this feedback control system. We measured intracellular hydrostatic pressures in mouse lenses using a microelectrode/manometer-based system. We found that all feedback went through transport by the Na/K ATPase, which adjusted surface cell osmolarity such that pressure was maintained at zero. We traced the regulation of Na/K ATPase activity back to either TRPV4, which sensed positive pressure and stimulated activity, or TRPV1, which sensed negative pressure and inhibited activity. The inhibitory effect of TRPV1 on Na/K pumps was shown to signal through activation of the PI3K/AKT axis. The stimulatory effect of TRPV4 was shown in previous studies to go through a different signal transduction path. Thus, there is a local two-legged feedback control system for pressure in lens surface cells. The surface pressure provides a pedestal on which the pressure gradient sits, so surface pressure determines the absolute value of pressure at each radial location. We speculate that the absolute value of intracellular pressure may set the radial gradient in the refractive index, which is essential for visual acuity. PMID:26536260

Pure and Oxidized Copper Materials as Potential Antimicrobial Surfaces for Spaceflight Activities

NASA Astrophysics Data System (ADS)

Hahn, C.; Hans, M.; Hein, C.; Mancinelli, R. L.; Mücklich, F.; Wirth, R.; Rettberg, P.; Hellweg, C. E.; Moeller, R.

2017-12-01

Microbial biofilms can lead to persistent infections and degrade a variety of materials, and they are notorious for their persistence and resistance to eradication. During long-duration space missions, microbial biofilms present a danger to crew health and spacecraft integrity. The use of antimicrobial surfaces provides an alternative strategy for inhibiting microbial growth and biofilm formation to conventional cleaning procedures and the use of disinfectants. Antimicrobial surfaces contain organic or inorganic compounds, such as antimicrobial peptides or copper and silver, that inhibit microbial growth. The efficacy of wetted oxidized copper layers and pure copper surfaces as antimicrobial agents was tested by applying cultures of Escherichia coli and Staphylococcus cohnii to these metallic surfaces. Stainless steel surfaces were used as non-inhibitory control surfaces. The production of reactive oxygen species and membrane damage increased rapidly within 1 h of exposure on pure copper surfaces, but the effect on cell survival was negligible even after 2 h of exposure. However, longer exposure times of up to 4 h led to a rapid decrease in cell survival, whereby the survival of cells was additionally dependent on the exposed cell density. Finally, the release of metal ions was determined to identify a possible correlation between copper ions in suspension and cell survival. These measurements indicated a steady increase of free copper ions, which were released indirectly by cells presumably through excreted complexing agents. These data indicate that the application of antimicrobial surfaces in spaceflight facilities could improve crew health and mitigate material damage caused by microbial contamination and biofilm formation. Furthermore, the results of this study indicate that cuprous oxide layers were superior to pure copper surfaces related to the antimicrobial effect and that cell density is a significant factor that influences the time dependence of antimicrobial activity.

Silicon surface passivation by silicon nitride deposition

NASA Technical Reports Server (NTRS)

Olsen, L. C.

1984-01-01

Silicon nitride deposition was studied as a method of passivation for silicon solar cell surfaces. The following three objectives were the thrust of the research: (1) the use of pecvd silicon nitride for passivation of silicon surfaces; (2) measurement techniques for surface recombination velocity; and (3) the importance of surface passivation to high efficiency solar cells.

Investigating biomolecular recognition at the cell surface using atomic force microscopy.

PubMed

Wang, Congzhou; Yadavalli, Vamsi K

2014-05-01

Probing the interaction forces that drive biomolecular recognition on cell surfaces is essential for understanding diverse biological processes. Force spectroscopy has been a widely used dynamic analytical technique, allowing measurement of such interactions at the molecular and cellular level. The capabilities of working under near physiological environments, combined with excellent force and lateral resolution make atomic force microscopy (AFM)-based force spectroscopy a powerful approach to measure biomolecular interaction forces not only on non-biological substrates, but also on soft, dynamic cell surfaces. Over the last few years, AFM-based force spectroscopy has provided biophysical insight into how biomolecules on cell surfaces interact with each other and induce relevant biological processes. In this review, we focus on describing the technique of force spectroscopy using the AFM, specifically in the context of probing cell surfaces. We summarize recent progress in understanding the recognition and interactions between macromolecules that may be found at cell surfaces from a force spectroscopy perspective. We further discuss the challenges and future prospects of the application of this versatile technique. Copyright © 2014 Elsevier Ltd. All rights reserved.

Surface micro- and nano-texturing of stainless steel by femtosecond laser for the control of cell migration.

PubMed

Martínez-Calderon, M; Manso-Silván, M; Rodríguez, A; Gómez-Aranzadi, M; García-Ruiz, J P; Olaizola, S M; Martín-Palma, R J

2016-11-02

The precise control over the interaction between cells and the surface of materials plays a crucial role in optimizing the integration of implanted biomaterials. In this regard, material surface with controlled topographic features at the micro- and nano-scales has been proved to affect the overall cell behavior and therefore the final osseointegration of implants. Within this context, femtosecond (fs) laser micro/nano machining technology was used in this work to modify the surface structure of stainless steel aiming at controlling cell adhesion and migration. The experimental results show that cells tend to attach and preferentially align to the laser-induced nanopatterns oriented in a specific direction. Accordingly, the laser-based fabrication method here described constitutes a simple, clean, and scalable technique which allows a precise control of the surface nano-patterning process and, subsequently, enables the control of cell adhesion, migration, and polarization. Moreover, since our surface-patterning approach does not involve any chemical treatments and is performed in a single step process, it could in principle be applied to most metallic materials.

Surface micro- and nano-texturing of stainless steel by femtosecond laser for the control of cell migration

PubMed Central

Martínez-Calderon, M.; Manso-Silván, M.; Rodríguez, A.; Gómez-Aranzadi, M.; García-Ruiz, J. P.; Olaizola, S. M.; Martín-Palma, R. J.

2016-01-01

The precise control over the interaction between cells and the surface of materials plays a crucial role in optimizing the integration of implanted biomaterials. In this regard, material surface with controlled topographic features at the micro- and nano-scales has been proved to affect the overall cell behavior and therefore the final osseointegration of implants. Within this context, femtosecond (fs) laser micro/nano machining technology was used in this work to modify the surface structure of stainless steel aiming at controlling cell adhesion and migration. The experimental results show that cells tend to attach and preferentially align to the laser-induced nanopatterns oriented in a specific direction. Accordingly, the laser-based fabrication method here described constitutes a simple, clean, and scalable technique which allows a precise control of the surface nano-patterning process and, subsequently, enables the control of cell adhesion, migration, and polarization. Moreover, since our surface-patterning approach does not involve any chemical treatments and is performed in a single step process, it could in principle be applied to most metallic materials. PMID:27805063

The effect of MTAD, an endodontic irrigant, on fibroblast attachment to periodontally affected root surfaces: A SEM analysis.

PubMed

Ghandi, Mostafa; Houshmand, Behzad; Nekoofar, Mohammad H; Tabor, Rachel K; Yadeghari, Zahra; Dummer, Paul M H

2013-03-01

Root surface debridement (RSD) is necessary to create an environment suitable for reattachment of the periodontium. Root surface conditioning may aid the formation of a biocompatible surface suitable for cell reattachment. BioPure™ MTAD (mixture of Doxycycline, citric acid and a detergent) is an endodontic irrigant with antibacterial properties and the ability to remove smear layer. It was hypothesized that MTAD may be useful for root surface conditioning. The efficacy of MTAD as a conditioner was measured by examining fibroblast attachment to root surfaces. Thirty-two specimens of human teeth with advanced periodontal disease were used. The surfaces were root planed until smooth. Half of the specimens were treated with 0.9% saline and the other samples with Biopure MTAD. As a negative control group, five further samples were left unscaled with surface calculus. Human gingival fibroblast cells HGF1-PI1 were cultured and poured over the tooth specimens and incubated. After fixation, the samples were sputter-coated with gold and examined with a SEM. The morphology and number of attached, fixed viable cells were examined. The data was analysed using the Mann-Whitney-U statistical test. There was no significant difference between the numbers of attached cells in the experimental group treated with MTAD and the control group treated with saline. Little or no attached cells were seen in the negative control group. RSD created an environment suitable for cell growth and attachment in a laboratory setting. The use of MTAD did not promote the attachment and growth of cells on the surface of human roots following RSD.

Engineered microtopographies and surface chemistries direct cell attachment and function

NASA Astrophysics Data System (ADS)

Magin, Chelsea Marie

Harrison, in 1914, first recognized that cells respond to physicochemical cues such as substratum topography when he observed that fibroblasts elongated while cultured on spider silk. Recently, techniques developed in the micro-electronics industry have been used to create molds for producing microscaled topographies with various shapes and spatial arrangements. Although these patterning techniques are well-established, very little is known about the mechanisms underlying cell sensing and response to microtopographies. In this work cellular micro-environments with varying surface topographies and chemistries were evaluated with marine organisms and mammalian cells to investigate cellular sensing and response. Biofouling---the accumulation of micro-organisms, plants, and animals on submerged surfaces---is an environmental and economic concern. Engineered topographies, replicated in polydimethylsiloxane elastomer (PDMSe) and functionalized poly(ethylene glycol)-dimethacrylate (PEGDMA) hydrogels, were evaluated for inhibition of marine fouling organism attachment. Microtopographies replicated in PDMSe inhibited attachment of the marine bacterium, Cobetia marina up to 99% versus smooth. The average normalized attachment densities of cells of C. marina and zoospores of the green algae Ulva on PDMSe topographies scaled inversely with the Engineered Roughness Index (ERIII), a representation of surface energy. Attachment densities of Ulva from four assays and C. marina from two growth phases to PDMSe surfaces scaled inversely with one equation: ERI II multiplied by the Reynolds number of the organism (Re) (R 2 = 0.77). The same microtopographies created in PDMSe reduced the initial attachment density and attachment strength of cells of the diatoms Navicula incerta and Seminavis robusta compared to smooth PDMSe. The average normalized attachment density of Navicula after exposure to shear stress (48 Pa) was correlated with the contact area between the diatom and a topographically modified surface (R2=0.82). Functionalized PEGDMA hydrogels significantly reduced attachment and attachment strength of Navicula and C. marina. These hydrogels also reduced attachment of zoospores of Ulva compared to PDMSe. Attachment of Ulva to microtopographies in PDMSe and PEGDMA-co-HEMA negatively correlated with ERIII*Re (R2 = 0.94 and R2 = 0.99, respectively). Incorporating a surface energy term into this equation created a correlation between the attachment densities of cells from two evolutionarily diverse groups on substrates of two surface chemistries with an equation that describes the various microtopographies and surface chemistries in terms of surface energy (R2 = 0.80). The current Attachment Model can now be used to design engineered antifouling surface microtopographies and chemistries that inhibit the attachment of organisms from three evoluntionarily diverse groups. Hydrogels based on PEGDMA were also chosen as a substratum material for mammalian cell culture. Capturing endothelial progenitor cells (EPCs) and inducing differentiation into the endothelial cell (EC) phenotype is the ideal way to re-endothelialize a small-diameter vascular graft. Substratum elasticity has been reported to direct stem cell differentiation into specific lineages. Functionalized PEGDMA hydrogels provided good compliance, high fidelity of topographic features and sites for surface modification with biomolecules. Fibronectin grafting and topography both increased EC attachment. This combination of adjustable elasticity, surface chemistry and topography has the potential to promote the capture and differentiation of EPCs into a confluent EC monolayer. Engineered microtopographies replicated in PDMSe directed elongation and alignment of human coronary artery endothelial cells (HCAECs) and human coronary artery smooth muscle cells (HCASMCs) compared to smooth surfaces. Engineered cellular micro-environments were created with specific surface energies defined by chemistry and topography to successfully direct cell attachment and function.

Nano-hydroxyapatite-coated metal-ceramic composite of iron-tricalcium phosphate: Improving the surface wettability, adhesion and proliferation of mesenchymal stem cells in vitro.

PubMed

Surmeneva, Maria A; Kleinhans, Claudia; Vacun, Gabriele; Kluger, Petra Juliane; Schönhaar, Veronika; Müller, Michaela; Hein, Sebastian Boris; Wittmar, Alexandra; Ulbricht, Mathias; Prymak, Oleg; Oehr, Christian; Surmenev, Roman A

2015-11-01

Thin radio-frequency magnetron sputter deposited nano-hydroxyapatite (HA) films were prepared on the surface of a Fe-tricalcium phosphate (Fe-TCP) bioceramic composite, which was obtained using a conventional powder injection moulding technique. The obtained nano-hydroxyapatite coated Fe-TCP biocomposites (nano-HA-Fe-TCP) were studied with respect to their chemical and phase composition, surface morphology, water contact angle, surface free energy and hysteresis. The deposition process resulted in a homogeneous, single-phase HA coating. The ability of the surface to support adhesion and the proliferation of human mesenchymal stem cells (hMSCs) was studied using biological short-term tests in vitro. The surface of the uncoated Fe-TCP bioceramic composite showed an initial cell attachment after 24h of seeding, but adhesion, proliferation and growth did not persist during 14 days of culture. However, the HA-Fe-TCP surfaces allowed cell adhesion, and proliferation during 14 days. The deposition of the nano-HA films on the Fe-TCP surface resulted in higher surface energy, improved hydrophilicity and biocompatibility compared with the surface of the uncoated Fe-TCP. Furthermore, it is suggested that an increase in the polar component of the surface energy was responsible for the enhanced cell adhesion and proliferation in the case of the nano-HA-Fe-TCP biocomposites. Copyright © 2015 Elsevier B.V. All rights reserved.

In vitro adhesion of fibroblastic cells to titanium alloy discs treated with sodium hydroxide.

PubMed

Al Mustafa, Maisa; Agis, Hermann; Müller, Heinz-Dieter; Watzek, Georg; Gruber, Reinhard

2015-01-01

Adhesion of osteogenic cells on titanium surfaces is a prerequisite for osseointegration. Alkali treatment can increase the hydrophilicity of titanium implant surfaces, thereby supporting the adhesion of blood components. However, it is unclear if alkali treatment also supports the adhesion of cells with a fibroblastic morphology to titanium. Here, we have used a titanium alloy (Ti-6AL-4V) processed by alkali treatment to demonstrate the impact of hydrophilicity on the adhesion of primary human gingival fibroblast and bone cells. Also included were the osteosarcoma and fibroblastoma cell lines, MG63 and L929, respectively. Cell adhesion was determined by scanning electron microscopy. We also measured viability, proliferation, and protein synthesis of the adherent cells. Alkali treatment increased the adhesion of gingival fibroblasts, bone cells, and the two cell lines when seeded onto the titanium alloy surface for 1 h. At 3 h, no significant changes in cell adhesion were observed. Cells grown for 1 day on the titanium alloy surfaces processed by alkali treatment behave similarly to untreated controls with regard to viability, proliferation, and protein synthesis. Based on these preliminary In vitro findings, we conclude that alkali treatment can support the early adhesion of cells with fibroblastic characteristics to a titanium alloy surface. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Biomimetic surface patterning for long-term transmembrane access

PubMed Central

VanDersarl, Jules J.; Renaud, Philippe

2016-01-01

Here we present a planar patch clamp chip based on biomimetic cell membrane fusion. This architecture uses nanometer length-scale surface patterning to replicate the structure and function of membrane proteins, creating a gigaohm seal between the cell and a planar electrode array. The seal is generated passively during cell spreading, without the application of a vacuum to the cell surface. This interface can enable cell-attached and whole-cell recordings that are stable to 72 hours, and generates no visible damage to the cell. The electrodes can be very small (<5 μm) and closely packed, offering a high density platform for cellular measurement. PMID:27577519

Biomimetic surface patterning for long-term transmembrane access.

PubMed

VanDersarl, Jules J; Renaud, Philippe

2016-08-31

Here we present a planar patch clamp chip based on biomimetic cell membrane fusion. This architecture uses nanometer length-scale surface patterning to replicate the structure and function of membrane proteins, creating a gigaohm seal between the cell and a planar electrode array. The seal is generated passively during cell spreading, without the application of a vacuum to the cell surface. This interface can enable cell-attached and whole-cell recordings that are stable to 72 hours, and generates no visible damage to the cell. The electrodes can be very small (<5 μm) and closely packed, offering a high density platform for cellular measurement.

Biophysical model of bacterial cell interactions with nanopatterned cicada wing surfaces.

PubMed

Pogodin, Sergey; Hasan, Jafar; Baulin, Vladimir A; Webb, Hayden K; Truong, Vi Khanh; Phong Nguyen, The Hong; Boshkovikj, Veselin; Fluke, Christopher J; Watson, Gregory S; Watson, Jolanta A; Crawford, Russell J; Ivanova, Elena P

2013-02-19

The nanopattern on the surface of Clanger cicada (Psaltoda claripennis) wings represents the first example of a new class of biomaterials that can kill bacteria on contact based solely on their physical surface structure. The wings provide a model for the development of novel functional surfaces that possess an increased resistance to bacterial contamination and infection. We propose a biophysical model of the interactions between bacterial cells and cicada wing surface structures, and show that mechanical properties, in particular cell rigidity, are key factors in determining bacterial resistance/sensitivity to the bactericidal nature of the wing surface. We confirmed this experimentally by decreasing the rigidity of surface-resistant strains through microwave irradiation of the cells, which renders them susceptible to the wing effects. Our findings demonstrate the potential benefits of incorporating cicada wing nanopatterns into the design of antibacterial nanomaterials. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Expression of bovine non-classical major histocompatibility complex class I proteins in mouse P815 and human K562 cells.

PubMed

Parasar, Parveen; Wilhelm, Amanda; Rutigliano, Heloisa M; Thomas, Aaron J; Teng, Lihong; Shi, Bi; Davis, William C; Suarez, Carlos E; New, Daniel D; White, Kenneth L; Davies, Christopher J

2016-08-01

Major histocompatibility complex class I (MHC-I) proteins can be expressed as cell surface or secreted proteins. To investigate whether bovine non-classical MHC-I proteins are expressed as cell surface or secreted proteins, and to assess the reactivity pattern of monoclonal antibodies with non-classical MHC-I isoforms, we expressed the MHC proteins in murine P815 and human K562 (MHC-I deficient) cells. Following antibiotic selection, stably transfected cell lines were stained with H1A or W6/32 antibodies to detect expression of the MHC-I proteins by flow cytometry. Two non-classical proteins (BoLA-NC1*00501 and BoLA-NC3*00101) were expressed on the cell surface in both cell lines. Surprisingly, the BoLA-NC4*00201 protein was expressed on the cell membrane of human K562 but not mouse P815 cells. Two non-classical proteins (BoLA-NC1*00401, which lacks a transmembrane domain, and BoLA-NC2*00102) did not exhibit cell surface expression. Nevertheless, Western blot analyses demonstrated expression of the MHC-I heavy chain in all transfected cell lines. Ammonium-sulfate precipitation of proteins from culture supernatants showed that BoLA-NC1*00401 was secreted and that all surface expressed proteins where shed from the cell membrane by the transfected cells. Interestingly, the surface expressed MHC-I proteins were present in culture supernatants at a much higher concentration than BoLA-NC1*00401. This comprehensive study shows that bovine non-classical MHC-I proteins BoLA-NC1*00501, BoLA-NC3*00101, and BoLA-NC4*00201 are expressed as surface isoforms with the latter reaching the cell membrane only in K562 cells. Furthermore, it demonstrated that BoLA-NC1*00401 is a secreted isoform and that significant quantities of membrane associated MHC-I proteins can be shed from the cell membrane. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effects of topographical and mechanical property alterations induced by oxygen plasma modification on stem cell behavior.

PubMed

Yang, Yong; Kulangara, Karina; Lam, Ruby T S; Dharmawan, Rena; Leong, Kam W

2012-10-23

Polymeric substrates intended for cell culture and tissue engineering are often surface-modified to facilitate cell attachment of most anchorage-dependent cell types. The modification alters the surface chemistry and possibly topography. However, scant attention has been paid to other surface property alterations. In studying oxygen plasma treatment of polydimethylsiloxane (PDMS), we show that oxygen plasma treatment alters the surface chemistry and, consequently, the topography and elasticity of PDMS at the nanoscale level. The elasticity factor has the predominant effect, compared with the chemical and topographical factors, on cell adhesions of human mesenchymal stem cells (hMSCs). The enhanced focal adhesions favor cell spreading and osteogenesis of hMSCs. Given the prevalent use of PDMS in biomedical device construction and cell culture experiments, this study highlights the importance of understanding how oxygen plasma treatment would impact subsequent cell-substrate interactions. It helps explain inconsistency in the literature and guides preparation of PDMS-based biomedical devices in the future.

Molecular Chaperone BiP Interacts with Borna Disease Virus Glycoprotein at the Cell Surface▿ †

PubMed Central

Honda, Tomoyuki; Horie, Masayuki; Daito, Takuji; Ikuta, Kazuyoshi; Tomonaga, Keizo

2009-01-01

Borna disease virus (BDV) is characterized by highly neurotropic infection. BDV enters its target cells using virus surface glycoprotein (G), but the cellular molecules mediating this process remain to be elucidated. We demonstrate here that the N-terminal product of G, GP1, interacts with the 78-kDa chaperone protein BiP. BiP was found at the surface of BDV-permissive cells, and anti-BiP antibody reduced BDV infection as well as GP1 binding to the cell surface. We also reveal that BiP localizes at the synapse of neurons. These results indicate that BiP may participate in the cell surface association of BDV. PMID:19776128

On physical changes on surface of human cervical epithelial cells during cancer transformations

NASA Astrophysics Data System (ADS)

Sokolov, Igor; Dokukin, Maxim; Guz, Nataliia; Woodworth, Craig

2013-03-01

Physical changes of the cell surface of cells during transformation from normal to cancerous state are rather poorly studied. Here we describe our recent studies of such changes done on human cervical epithelial cells during their transformation from normal through infected with human papillomavirus type-16 (HPV-16), immortalized (precancerous), to cancerous cells. The changes were studied with the help of atomic force microscopy (AFM) and through the measurement of physical adhesion of fluorescent silica beads to the cell surface. Based on the adhesion experiments, we clearly see the difference in nonspecific adhesion which occurs at the stage of immortalization of cells, precancerous cells. The analysis done with the help of AFM shows that the difference observed comes presumably from the alteration of the cellular ``brush,'' a layer that surrounds cells and which consists of mostly microvilli, microridges, and glycocalyx. Further AFM analysis reveals the emergence of fractal scaling behavior on the surface of cells when normal cells turn into cancerous. The possible causes and potential significance of these observations will be discussed.

Preparation of Caco-2 cell sheets using plasma polymerised acrylic acid as a weak boundary layer.

PubMed

Majani, Ruby; Zelzer, Mischa; Gadegaard, Nikolaj; Rose, Felicity R; Alexander, Morgan R

2010-09-01

The use of cell sheets for tissue engineering applications has considerable advantages over single cell seeding techniques. So far, only thermoresponsive surfaces have been used to manufacture cell sheets without chemically disrupting the cell-surface interactions. Here, we present a new and facile technique to prepare sheets of epithelial cells using plasma polymerised acrylic acid films. The cell sheets are harvested by gentle agitation of the media without the need of any additional external stimulus. We demonstrate that the plasma polymer deposition conditions affect the viability and metabolic activity of the cells in the sheet and relate these effects to the different surface properties of the plasma polymerised acrylic acid films. Based on surface analysis data, a first attempt is made to explain the mechanism behind the cell sheet formation. The advantage of the epithelial cell sheets generated here over single cell suspensions to seed a PLGA scaffold is presented. The scaffold itself, prepared using a mould fabricated via photolithography, exhibits a unique architecture that mimics closely the dimensions of the native tissue (mouse intestine). Copyright 2010 Elsevier Ltd. All rights reserved.

Functional Anchoring Lipids for Drug Delivery Carrier Fabrication and Cell Surface Re-Engineering Applications

NASA Astrophysics Data System (ADS)

Vabbilisetty, Pratima

For decades, lipid vesicular bodies such as liposomes have been widely used and explored as biomimetic models of cell membranes and as drug/gene delivery carrier systems. Similarly, micellar iron oxide nanoparticles have also been investigated as potential MRI agents as well as drug delivery carrier systems. Cell surface carbohydrate-protein interactions allow them to serve as markers for recognition of many molecular and cellular activities thereby, are exploited as attractive molecules for surface modification of nanocarrier systems with purpose for tissues specific targeting and biocompatibility. In addition, the cell lipid membrane serves as an important platform for occurrence of many biological processes that are governed and guided by cell surface receptors. Introduction of chemoselective functional groups, via bio-orthogonal conjugation strategies, at the cell surface facilitates many cellular modifications and paves path for novel and potential biomedical applications. Anchoring lipids are needed for liposome surface functionalization with ligands of interest and play important roles in ligand grafting density, liposomes stability and biological activity. On the other hand, anchoring lipids are also needed for cell surface re-engineering by lipid fusion approach and have high impact for ligand insertion efficiency and biological activity. Overall, in this dissertation study, functional anchoring lipids for glyco-functionalized carrier systems and for efficient cell surface re-engineering applications were systematically investigated, respectively. Firstly, investigation of the synthesis of glyco-functionalized liposome systems based on phosphatidylethonalamine (PE) and cholesterol (Chol) anchoring lipids, prepared by post chemically selective functionalization via Staudinger ligation were carried out. The effect of anchor lipids on the stability, encapsulation and releasing capacity of the glycosylated liposomes were investigated by dynamic light scattering (DLS) technique and by entrapping 5, 6-carboxyfluorescein (CF) dye and monitoring the fluorescence leakage, respectively. Overall, the Chol-anchored liposomes showed faster releasing rate than DSPE-anchored liposomes. This could be due to the increase in rigidity of the lipid membrane upon inclusion of Chol, thereby, leading to fast leakage of liposomes. Second, the potential effects of phospholipid (PE) and cholesterol (Chol)-based anchor lipids on cell surface re-engineering via copper free click chemistry were assessed with RAW 264.7 cells as model. The confocal microscopy and flow cytometry results indicated the successful incorporation of biotinylated Chol-based anchor lipids after specific streptavidin-FITC binding onto the cell surface. Higher fluorescence intensities from the cell membrane were observed for Chol-based anchor lipids when compared to DSPE as anchoring lipid. Furthermore, cytotoxicity of the synthesized biotinylated anchor lipids on the RAW 264.7 cells was assessed by MTT assay. The MTT assay results further confirmed that cell surface re-engineering via lipid anchoring approach strategy has very little or negligible amount of cytotoxicity on the cell viability. Thus, this study suggests the possible use of these lipids for potential cell surface re-engineering applications. In addition, synthesis of lipid coated iron oxide nanoparticles via dual solvent exchange approach and their glyco-functionalization via Staudinger ligation were investigated and characterized by FT-IR and TEM techniques. The stability of iron oxide nanoparticles with varying compositions of lipid anchors was evaluated by dynamic light scattering technique.

The fine structure of the stomach mucosa of the Llama (Llama guanacoe). II. The fundic region of the hind stomach.

PubMed

Luciano, L; Reale, E; von Engelhardt, W

1980-01-01

The epithelium of the fundic region mucosa of the hind stomach in the Llama guanacoe has been studied using morphological and histochemical methods. Morphology suggests that solute and water absorption may occur in the epithelium of the surface and of the foveolae, although this absorption can not be estimated because of the extensive secretion of the gastric glands. The same cells of the surface and foveolar epithelium show numerous secretory granules. The glands reveal neck cells, chief cells, a large number of oxyntic cells, four types of endocrine cells (A-like, ECL, D and EC), brush cells and wandering cells. PAS and Alcian blue reactions for light microscopy suggest a secretion of neutral and acidic mucosubstances in the surface and foveolar epithelium, of neutral mucosubstances only in the neck cells. Periodic acid-thiocarbohydrazide silver proteinate (PA-TCH-SP) reaction for electron microscopy confirms the presence of neutral mucosubstances within the secretory granules of the surface, foveolar and neck epithelial cells. In all these cells, the reaction product is also evident within sacculi and vesicles of the maturing surface of the Golgi apparatus. A positive PA-TCH-SP reaction also occurs on the membrane (and not on the contents) of the Golgi apparatus (maturing surface) and of the secretory granules of the chief cells as well as on the membrane of the Golgi apparatus and of apical vesicles and tubules of the oxyntic cells. In addition, silver granules slightly enhance the electron desity of the contents of the secretory granules in the endocrine cells. Morphological and histochemical findings are discussed and compared with results described by others for monogastric mammals.

Role of Outer Membrane C-Type Cytochromes MtrC and OmcA in Shewanella Oneidensis MR-1 Cell Production, Accumulation, and Detachment During Respiration on Hematite

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

Mitchell, Andrew C.; Peterson, L.; Reardon, Catherine L.

2012-07-01

Solid phase iron oxides are considered to be important terminal electron acceptors for microbial respiration in many anoxic environments. Besides the knowledge that cells attach to and reduce these substrates, other aspects of surface-associated cell behavior and the related cell surface components that influence cell-mineral interactions are not well understood. In the present study, wild-type cells of the dissimilatory iron-reducing bacterium Shewanella oneidensis MR-1 formed thin biofilms one-to-two cell layers in thickness when respiring on natural specular hematite under flow conditions similar to those which exist in aquatic sediments and subsurface environments. The distribution of cells within the biofilm indicatedmore » that direct contact was not required for electron transfer from cells to the mineral surface. Detached biomass in the form of single cells represented >99% of the surface-associated wild-type cell production from respiration on hematite over the biofilm life cycle. A mutant deficient in the outer membrane c35 type cytochrome OmcA, while still able to respire and replicate on hematite, established a lower steady-state cell density on the mineral surface than that of the wild-type strain. A mutant deficient in MtrC, another outer membrane c-type cytochrome, and a mutant deficient in both cytochromes were unable to reduce sufficient amounts of hematite to support detectable growth on the mineral surface. When considered in the context of previous work, the results support a growing body of evidence that the relative importance of OmcA and MtrC to cell respiration and replication depends on the form of iron oxide available as terminal electron acceptor.« less

Dendritic Cells: A Spot on Sialic Acid

PubMed Central

Crespo, Hélio J.; Lau, Joseph T. Y.; Videira, Paula A.

2013-01-01

Glycans decorating cell surface and secreted proteins and lipids occupy the juncture where critical host–host and host-pathogen interactions occur. The role of glycan epitopes in cell–cell and cell-pathogen adhesive events is already well-established, and cell surface glycan structures change rapidly in response to stimulus and inflammatory cues. Despite the wide acceptance that glycans are centrally implicated in immunity, exactly how glycans and their changes contribute to the overall immune response remains poorly defined. Sialic acids are unique sugars that usually occupy the terminal position of the glycan chains and may be modified by external factors, such as pathogens, or upon specific physiological cellular events. At cell surface, sialic acid-modified structures form the key fundamental determinants for a number of receptors with known involvement in cellular adhesiveness and cell trafficking, such as the Selectins and the Siglec families of carbohydrate recognizing receptors. Dendritic cells (DCs) preside over the transition from innate to the adaptive immune repertoires, and no other cell has such relevant role in antigen screening, uptake, and its presentation to lymphocytes, ultimately triggering the adaptive immune response. Interestingly, sialic acid-modified structures are involved in all DC functions, such as antigen uptake, DC migration, and capacity to prime T cell responses. Sialic acid content changes along DC differentiation and activation and, while, not yet fully understood, these changes have important implications in DC functions. This review focuses on the developmental regulation of DC surface sialic acids and how manipulation of DC surface sialic acids can affect immune-critical DC functions by altering antigen endocytosis, pathogen and tumor cell recognition, cell recruitment, and capacity for T cell priming. The existing evidence points to a potential of DC surface sialylation as a therapeutic target to improve and diversify DC-based therapies. PMID:24409183

T-Cell Surface Antigens and sCD30 as Biomarkers of the Risk of Rejection in Solid Organ Transplantation.

PubMed

Wieland, Eberhard; Shipkova, Maria

2016-04-01

T-cell activation is a characteristic of organ rejection. T cells, located in the draining lymph nodes of the transplant recipient, are faced with non-self-molecules presented by antigen presenting cells and become activated. Activated T cells are characterized by up-regulated surface antigens, such as costimulatory molecules, adhesion molecules, chemokine receptors, and major histocompatibility complex class II molecules. Surface antigen expression can be followed by flow cytometry using monoclonal antibodies in either cell function assays using donor-specific or nonspecific stimulation of isolated cells or whole blood and without stimulation on circulating lymphocytes. Molecules such as CD30 can be proteolytically cleaved off the surface of activated cells in vivo, and the determination of the soluble protein (sCD30) in serum or plasma is performed by immunoassays. As promising biomarkers for rejection and long-term transplant outcome, CD28 (costimulatory receptor for CD80 and CD86), CD154 (CD40 ligand), and sCD30 (tumor necrosis factor receptor superfamily, member 8) have been identified. Whereas cell function assays are time-consuming laboratory-developed tests which are difficult to standardize, commercial assays are frequently available for soluble proteins. Therefore, more data from clinical trials have been published for sCD30 compared with the surface antigens on activated T cells. This short review summarizes the association between selected surface antigens and immunosuppression, and rejection in solid organ transplantation.

Display of adenoregulin with a novel Pichia pastoris cell surface display system.

PubMed

Ren, Ren; Jiang, Zhengbing; Liu, Meiyun; Tao, Xinyi; Ma, Yushu; Wei, Dongzhi

2007-02-01

Two Pichia pastoris cell surface display vectors were constructed. The vectors consisted of the flocculation functional domain of Flo1p with its own secretion signal sequence or the alpha-factor secretion signal sequence, a polyhistidine (6xHis) tag for detection, an enterokinase recognition site, and the insertion sites for target proteins. Adenoregulin (ADR) is a 33-amino-acid antimicrobial peptide isolated from Phyllomedusa bicolor skin. The ADR was expressed and displayed on the Pichia pastoris KM71 cell surface with the system reported. The displayed recombinant ADR fusion protein was detected by fluorescence microscopy and confocal laser scanning microscopy (CLSM). The antimicrobial activity of the recombinant adenoregulin was detected after proteolytic cleavage of the fusion protein on cell surface. The validity of the Pichia pastoris cell surface display vectors was proved by the displayed ADR.

Natural bactericidal surfaces: mechanical rupture of Pseudomonas aeruginosa cells by cicada wings.

PubMed

Ivanova, Elena P; Hasan, Jafar; Webb, Hayden K; Truong, Vi Khanh; Watson, Gregory S; Watson, Jolanta A; Baulin, Vladimir A; Pogodin, Sergey; Wang, James Y; Tobin, Mark J; Löbbe, Christian; Crawford, Russell J

2012-08-20

Natural superhydrophobic surfaces are often thought to have antibiofouling potential due to their self-cleaning properties. However, when incubated on cicada wings, Pseudomonas aeruginosa cells are not repelled; instead they are penetrated by the nanopillar arrays present on the wing surface, resulting in bacterial cell death. Cicada wings are effective antibacterial, as opposed to antibiofouling, surfaces. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Final Report: Rational Design of Anode Surface Chemistry in Microbial Fuel Cells for Improved Exoelectrogen Attachment and Electron Transfer

DTIC Science & Technology

2015-12-21

SECURITY CLASSIFICATION OF: The overall goal of this project is to determine how electrode surface chemistry can be rationally designed to decrease...2015 Approved for Public Release; Distribution Unlimited Final Report: Rational Design of Anode Surface Chemistry in Microbial Fuel Cells for...ABSTRACT Final Report: Rational Design of Anode Surface Chemistry in Microbial Fuel Cells for Improved Exoelectrogen Attachment and Electron Transfer

An unscaled parameter to measure the order of surfaces: a new surface elaboration to increase cells adhesion.

PubMed

Bigerelle, M; Anselme, K; Dufresne, E; Hardouin, P; Iost, A

2002-08-01

We present a new parameter to quantify the order of a surface. This parameter is scale-independent and can be used to compare the organization of a surface at different scales of range and amplitude. To test the accuracy of this roughness parameter versus a hundred existing ones, we created an original statistical bootstrap method. In order to assess the physical relevance of this new parameter, we elaborated a great number of surfaces with various roughness amplitudes on titanium and titanium-based alloys using different physical processes. Then we studied the influence of the roughness amplitude on in vitro adhesion and proliferation of human osteoblasts. It was then shown that our new parameter best discriminates among the cell adhesion phenomena than others' parameters (Average roughness (Ra em leader )): cells adhere better on isotropic surfaces with a low order, provided this order is quantified on a scale that is more important than that of the cells. Additionally, on these low ordered metallic surfaces, the shape of the cells presents the same morphological aspect as that we can see on the human bone trabeculae. The method used to prepare these isotropic surfaces (electroerosion) could be undoubtedly and easily applied to prepare most biomaterials with complex geometries and to improve bone implant integration. Moreover, the new order parameter we developed may be particularly useful for the fundamental understanding of the mechanism of bone cell installation on a relief and of the formation of bone cell-material interface.

Effects of spaceflight on levels and activity of immune cells

NASA Technical Reports Server (NTRS)

Sonnenfeld, Gerald; Berry, Wallace D.; Mandel, Adrian D.; Konstantinova, Irena V.; Taylor, Gerald R.

1990-01-01

Experiments were carried out on cells from rats that had been flown on Soviet Biosputnik Cosmos 1887 to explore the effects of speceflight on immune responses. Rat bone marrow cells were examined for their response to colony stimulating factor-M. Rat spleen and bone marrow cells were stained with antibodies directed against cell surface antigenic markers. The results of the studies indicate that bone marrow cells from flown rats showed a decreased response to colony stimulating factor. There was a higher percentage of spleen cells from flown rats staining positively for pan-T-cell, suppressor-T-cell, and interleukin-2 receptor cell surface antigens. A small increase in the percentage of cells staining positively for helper-T-cell antigens was also noted. In addition, a higher percentage of cells that appeared to be part of the myelogenous population of bone marrow cells from flown rats stained positively for surface immunoglobulin.

Cicada-inspired cell-instructive nanopatterned arrays

NASA Astrophysics Data System (ADS)

Diu, Ting; Faruqui, Nilofar; Sjöström, Terje; Lamarre, Baptiste; Jenkinson, Howard F.; Su, Bo; Ryadnov, Maxim G.

2014-11-01

Biocompatible surfaces hold key to a variety of biomedical problems that are directly related to the competition between host-tissue cell integration and bacterial colonisation. A saving solution to this is seen in the ability of cells to uniquely respond to physical cues on such surfaces thus prompting the search for cell-instructive nanoscale patterns. Here we introduce a generic rationale engineered into biocompatible, titanium, substrates to differentiate cell responses. The rationale is inspired by cicada wing surfaces that display bactericidal nanopillar patterns. The surfaces engineered in this study are titania (TiO2) nanowire arrays that are selectively bactericidal against motile bacteria, while capable of guiding mammalian cell proliferation according to the type of the array. The concept holds promise for clinically relevant materials capable of differential physico-mechanical responses to cellular adhesion.

Cicada-inspired cell-instructive nanopatterned arrays.

PubMed

Diu, Ting; Faruqui, Nilofar; Sjöström, Terje; Lamarre, Baptiste; Jenkinson, Howard F; Su, Bo; Ryadnov, Maxim G

2014-11-20

Biocompatible surfaces hold key to a variety of biomedical problems that are directly related to the competition between host-tissue cell integration and bacterial colonisation. A saving solution to this is seen in the ability of cells to uniquely respond to physical cues on such surfaces thus prompting the search for cell-instructive nanoscale patterns. Here we introduce a generic rationale engineered into biocompatible, titanium, substrates to differentiate cell responses. The rationale is inspired by cicada wing surfaces that display bactericidal nanopillar patterns. The surfaces engineered in this study are titania (TiO2) nanowire arrays that are selectively bactericidal against motile bacteria, while capable of guiding mammalian cell proliferation according to the type of the array. The concept holds promise for clinically relevant materials capable of differential physico-mechanical responses to cellular adhesion.

Early detection of disease program: Evaluation of the cellular immune response

NASA Technical Reports Server (NTRS)

Criswell, B. S.; Knight, V.; Martin, R. R.; Kasel, J. A.

1975-01-01

Surfaces of normal, cultured, and mitogen-stimulated mouse lymphoid cells were examined by scanning electron microscopy (SEM). Lymphocytes with smooth, highly villous and intermediate surfaces were observed in cell suspensions from both spleens and thymuses of normal mice and from spleens of congenitally athymic (nude) mice. Several strain-specific surface features were noted, including the spine-like appearance of microvilli on C57B1/6 lymphocytes. Although thymus cell suspensions contained somewhat more smooth cells than did spleen cell preparations, lymphocyte derivation could not be inferred from SEM examination. Studies of cells stimulated with mitogenic agents for thymus-derived lymphocytes (concanavalin A) or for bone marrow-derived lymphocytes (lipopolysaccharide) suggested that, in the mouse, development of a complex villous surface is a general concomitant of lymphocyte activation and transformation.

Sheet plastic filters for solar cells

NASA Technical Reports Server (NTRS)

Wizenick, R. J.

1972-01-01

Poly(vinylidene fluoride) (PVF) film protects solar cells on Mars surface from radiation and prevents degradation of solar cell surfaces by Martian dust storms. PVF films may replace glass or quartz windows on solar cell arrays used to generate power on earth.

Loss of FliL alters Proteus mirabilis surface sensing and temperature-dependent swarming.

PubMed

Lee, Yi-Ying; Belas, Robert

2015-01-01

Proteus mirabilis is a dimorphic motile bacterium well known for its flagellum-dependent swarming motility over surfaces. In liquid, P. mirabilis cells are 1.5- to 2.0-μm swimmer cells with 4 to 6 flagella. When P. mirabilis encounters a solid surface, where flagellar rotation is limited, swimmer cells differentiate into elongated (10- to 80-μm), highly flagellated swarmer cells. In order for P. mirabilis to swarm, it first needs to detect a surface. The ubiquitous but functionally enigmatic flagellar basal body protein FliL is involved in P. mirabilis surface sensing. Previous studies have suggested that FliL is essential for swarming through its involvement in viscosity-dependent monitoring of flagellar rotation. In this study, we constructed and characterized ΔfliL mutants of P. mirabilis and Escherichia coli. Unexpectedly and unlike other fliL mutants, both P. mirabilis and E. coli ΔfliL cells swarm (Swr(+)). Further analysis revealed that P. mirabilis ΔfliL cells also exhibit an alteration in their ability to sense a surface: e.g., ΔfliL P. mirabilis cells swarm precociously over surfaces with low viscosity that normally impede wild-type swarming. Precocious swarming is due to an increase in the number of elongated swarmer cells in the population. Loss of fliL also results in an inhibition of swarming at <30°C. E. coli ΔfliL cells also exhibit temperature-sensitive swarming. These results suggest an involvement of FliL in the energetics and function of the flagellar motor. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Adsorption and transport of charged vs. neutral hydrophobic molecules at the membrane of murine erythroleukemia (MEL) cells.

PubMed

Zeng, Jia; Eckenrode, Heather M; Dai, Hai-Lung; Wilhelm, Michael J

2015-03-01

The adsorption and transport of hydrophobic molecules at the membrane surface of pre- and post-DMSO induced differentiated murine erythroleukemia (MEL) cells were examined by time- and wavelength-resolved second harmonic light scattering. Two medium (<600 Da) hydrophobic molecules, cationic malachite green (MG) and neutral bromocresol purple (BCP), were investigated. While it was observed that the MG cation adsorbs onto the surface of the MEL cell, neutral BCP does not. It is suggested that an electrostatic interaction between the opposite charges of the cation and the MEL cell surface is the primary driving force for adsorption. Comparisons of adsorption density and free energy, measured at different pH and cell morphology, indicate that the interaction is predominantly through sialic acid carboxyl groups. MG cation adsorption densities have been determined as (0.6±0.3)×10(6) μm(-2) on the surface of undifferentiated MEL cells, and (1.8±0.5)×10(7) μm(-2) on differentiated MEL cells, while the deduced adsorption free energies are effectively identical (ca. -10.9±0.1 and -10.8±0.1 kcal mol(-1), respectively). The measured MG densities indicate that the total number of surface carboxyl groups is largely conserved following differentiation, and therefore the density of carboxylic groups is much larger on the differentiated cell surface than the undifferentiated one. Finally, in contrast to synthetic liposomes and bacterial membranes, surface adsorbed MG cations are unable to traverse the MEL cell membrane. Copyright © 2015 Elsevier B.V. All rights reserved.

The responses of immune cells to iron oxide nanoparticles.

PubMed

Xu, Yaolin; Sherwood, Jennifer A; Lackey, Kimberly H; Qin, Ying; Bao, Yuping

2016-04-01

Immune cells play an important role in recognizing and removing foreign objects, such as nanoparticles. Among various parameters, surface coatings of nanoparticles are the first contact with biological system, which critically affect nanoparticle interactions. Here, surface coating effects on nanoparticle cellular uptake, toxicity and ability to trigger immune response were evaluated on a human monocyte cell line using iron oxide nanoparticles. The cells were treated with nanoparticles of three types of coatings (negatively charged polyacrylic acid, positively charged polyethylenimine and neutral polyethylene glycol). The cells were treated at various nanoparticle concentrations (5, 10, 20, 30, 50 μg ml(-1) or 2, 4, 8, 12, 20 μg cm(-2)) with 6 h incubation or treated at a nanoparticle concentration of 50 μg ml(-1) (20 μg cm(-2)) at different incubation times (6, 12, 24, 48 or 72 h). Cell viability over 80% was observed for all nanoparticle treatment experiments, regardless of surface coatings, nanoparticle concentrations and incubation times. The much lower cell viability for cells treated with free ligands (e.g. ~10% for polyethylenimine) suggested that the surface coatings were tightly attached to the nanoparticle surfaces. The immune responses of cells to nanoparticles were evaluated by quantifying the expression of toll-like receptor 2 and tumor necrosis factor-α. The expression of tumor necrosis factor-α and toll-like receptor 2 were not significant in any case of the surface coatings, nanoparticle concentrations and incubation times. These results provide useful information to select nanoparticle surface coatings for biological and biomedical applications. Copyright © 2016 John Wiley & Sons, Ltd.

Surface Expression of Hsp25 and Hsp72 Differentially Regulates Tumor Growth and Metastasis

PubMed Central

Bausero, María A.; Page, Diana T.; Osinaga, Eduardo; Asea, Alexzander

2006-01-01

The expression of unique surface structures on tumors that allow for recognition and activation of host immunocompetent cells plays an important role in determining tumor growth and/or metastasis. Recent studies have identified an important role for heat shock proteins (Hsp) in antitumor surveillance; however, the exact role of Hsp expressed on the surface of tumors has not been fully addressed. In this study, we show that 4T1 mammary adenocarcinoma cells sorted for high Hsp25 surface expression (Hsp25high) grow significantly faster than cells sorted for intermediate Hsp25 surface expression (Hsp25intermediate) or wild-type 4T1 cells implanted into the abdominal breast gland of female BALB/c mice (p < 0.05). In addition, histological examination of lung tissues revealed that Hsp25high 4T1 cells metastasized to the lungs more aggressively than either Hsp25intermediate or wild-type 4T1 cells (p < 0.05). Exposure of 4T1 cells to nonlethal heat shock (43°C, 30 min) induced the surface expression of Hsp72 and a concomitant reduction in Hsp25 surface expression. The growth and metastastic potential of Hsp72+ 4T1 cells was significantly less than that of Hsp25high, Hsp25intermediate or wild-type 4T1 cells (p < 0.05). Taken together, these studies identify an important role for expression of Hsp25 and Hsp72 during tumor growth and metastatic spread which might be helpful in the design of antimetastatic therapies. PMID:15627887

Surface expression of Hsp25 and Hsp72 differentially regulates tumor growth and metastasis.

PubMed

Bausero, María A; Page, Diana T; Osinaga, Eduardo; Asea, Alexzander

2004-01-01

The expression of unique surface structures on tumors that allow for recognition and activation of host immunocompetent cells plays an important role in determining tumor growth and/or metastasis. Recent studies have identified an important role for heat shock proteins (Hsp) in antitumor surveillance; however, the exact role of Hsp expressed on the surface of tumors has not been fully addressed. In this study, we show that 4T1 mammary adenocarcinoma cells sorted for high Hsp25 surface expression (Hsp25(high)) grow significantly faster than cells sorted for intermediate Hsp25 surface expression (Hsp25(intermediate)) or wild-type 4T1 cells implanted into the abdominal breast gland of female BALB/c mice (p < 0.05). In addition, histological examination of lung tissues revealed that Hsp25(high) 4T1 cells metastasized to the lungs more aggressively than either Hsp25(intermediate) or wild-type 4T1 cells (p < 0.05). Exposure of 4T1 cells to nonlethal heat shock (43 degrees C, 30 min) induced the surface expression of Hsp72 and a concomitant reduction in Hsp25 surface expression. The growth and metastastic potential of Hsp72(+) 4T1 cells was significantly less than that of Hsp25(high), Hsp25(intermediate) or wild-type 4T1 cells (p < 0.05). Taken together, these studies identify an important role for expression of Hsp25 and Hsp72 during tumor growth and metastatic spread which might be helpful in the design of antimetastatic therapies. Copyright 2004 S. Karger AG, Basel.

Surface-charge-dependent cell localization and cytotoxicity of cerium oxide nanoparticles.

PubMed

Asati, Atul; Santra, Santimukul; Kaittanis, Charalambos; Perez, J Manuel

2010-09-28

Cerium oxide nanoparticles (nanoceria) have shown great potential as antioxidant and radioprotective agents for applications in cancer therapy. Recently, various polymer-coated nanoceria preparations have been developed to improve their aqueous solubility and allow for surface functionalization of these nanoparticles. However, the interaction of polymer-coated nanoceria with cells, their uptake mechanism, and subcellular localization are poorly understood. Herein, we engineered polymer-coated cerium oxide nanoparticles with different surface charges (positive, negative, and neutral) and studied their internalization and toxicity in normal and cancer cell lines. The results showed that nanoceria with a positive or neutral charge enters most of the cell lines studied, while nanoceria with a negative charge internalizes mostly in the cancer cell lines. Moreover, upon entry into the cells, nanoceria is localized to different cell compartments (e.g., cytoplasm and lysosomes) depending on the nanoparticle's surface charge. The internalization and subcellular localization of nanoceria plays a key role in the nanoparticles' cytotoxicity profile, exhibiting significant toxicity when they localize in the lysosomes of the cancer cells. In contrast, minimal toxicity is observed when they localize into the cytoplasm or do not enter the cells. Taken together, these results indicate that the differential surface-charge-dependent localization of nanoceria in normal and cancer cells plays a critical role in the nanoparticles' toxicity profile.

Dominant-Negative Regulation of Cell Surface Expression by a Pentapeptide Motif at the Extreme COOH Terminus of an Slo1 Calcium-Activated Potassium Channel Splice Variant

PubMed Central

Chiu, Yu-Hsin; Alvarez-Baron, Claudia; Kim, Eun Young

2010-01-01

Large-conductance Ca2+-activated K+ (BKCa) channels regulate the physiology of many cell types. A single vertebrate gene variously known as Slo1, KCa1.1, or KCNMA1 encodes the pore-forming subunits of BKCa channel but is expressed in a potentially very large number of alternative splice variants. Two splice variants of Slo1, Slo1VEDEC and Slo1QEERL, which differ at the extreme COOH terminus, show markedly different steady-state expression levels on the cell surface. Here we show that Slo1VEDEC and Slo1QEERL can reciprocally coimmunoprecipitate, indicating that they form heteromeric complexes. Moreover, coexpression of even small amounts of Slo1VEDEC markedly reduces surface expression of Slo1QEERL and total Slo1 as indicated by cell-surface biotinylation assays. The effects of Slo1VEDEC on steady-state surface expression can be attributed primarily to the last five residues of the protein based on surface expression of motif-swapped constructs of Slo1 in human embryonic kidney (HEK) 293T cells. In addition, the presence of the VEDEC motif at the COOH terminus of Slo1 channels is sufficient to confer a dominant-negative effect on cell surface expression of itself or other types of Slo1 subunits. Treating cells with short peptides containing the VEDEC motif increased surface expression of Slo1VEDEC channels transiently expressed in HEK293T cells and increased current through endogenous BKCa channels in mouse podocytes. Slo1VEDEC and Slo1QEERL channels are removed from the HEK293T cell surface with similar kinetics and to a similar extent, which suggests that the inhibitory effect of the VEDEC motif is exerted primarily on forward trafficking into the plasma membrane. PMID:20051533

Constrained Adherable Area of Nanotopographic Surfaces Promotes Cell Migration through the Regulation of Focal Adhesion via Focal Adhesion Kinase/Rac1 Activation.

PubMed

Lim, Jiwon; Choi, Andrew; Kim, Hyung Woo; Yoon, Hyungjun; Park, Sang Min; Tsai, Chia-Hung Dylan; Kaneko, Makoto; Kim, Dong Sung

2018-05-02

Cell migration is crucial in physiological and pathological processes such as embryonic development and wound healing; such migration is strongly guided by the surrounding nanostructured extracellular matrix. Previous studies have extensively studied the cell migration on anisotropic nanotopographic surfaces; however, only a few studies have reported cell migration on isotropic nanotopographic surfaces. We herein, for the first time, propose a novel concept of adherable area on cell migration using isotropic nanopore surfaces with sufficient nanopore depth by adopting a high aspect ratio. As the pore size of the nanopore surface was controlled to 200, 300, and 400 nm in a fixed center-to-center distance of 480 nm, it produced 86, 68, and 36% of adherable area, respectively, on the fabricated surface. A meticulous investigation of the cell migration in response to changes in the constrained adherable area of the nanotopographic surface showed 1.4-, 1.5-, and 1.6-fold increase in migration speeds and a 1.4-, 2-, and 2.5-fold decrease in the number of focal adhesions as the adherable area was decreased to 86, 68, and 36%, respectively. Furthermore, a strong activation of FAK/Rac1 signaling was observed to be involved in the promoted cell migration. These results suggest that the reduced adherable area promotes cell migration through decreasing the FA formation, which in turn upregulates FAK/Rac1 activation. The findings in this study can be utilized to control the cell migration behaviors, which is a powerful tool in the research fields involving cell migration such as promoting wound healing and tissue repair.

Surface proteins and the formation of biofilms by Staphylococcus aureus.

PubMed

Kim, Sung Joon; Chang, James; Rimal, Binayak; Yang, Hao; Schaefer, Jacob

2018-03-01

Staphylococcus aureus biofilms pose a serious clinical threat as reservoirs for persistent infections. Despite this clinical significance, the composition and mechanism of formation of S. aureus biofilms are unknown. To address these problems, we used solid-state NMR to examine S. aureus (SA113), a strong biofilm-forming strain. We labeled whole cells and cell walls of planktonic cells, young biofilms formed for 12-24h after stationary phase, and more mature biofilms formed for up to 60h after stationary phase. All samples were labeled either by (i) [ 15 N]glycine and l-[1- 13 C]threonine, or in separate experiments, by (ii) l-[2- 13 C, 15 N]leucine. We then measured 13 C- 15 N direct bonds by C{N} rotational-echo double resonance (REDOR). The increase in peptidoglycan stems that have bridges connected to a surface protein was determined directly by a cell-wall double difference (biofilm REDOR difference minus planktonic REDOR difference). This procedure eliminates errors arising from differences in 15 N isotopic enrichments and from the routing of 13 C label from threonine degradation to glycine. For both planktonic cells and the mature biofilm, 20% of pentaglycyl bridges are not cross-linked and are potential surface-protein attachment sites. None of these sites has a surface protein attached in the planktonic cells, but one-fourth have a surface protein attached in the mature biofilm. Moreover, the leucine-label shows that the concentration of β-strands in leucine-rich regions doubles in the mature biofilm. Thus, a primary event in establishing a S. aureus biofilm is extensive decoration of the cell surface with surface proteins that are linked covalently to the cell wall and promote cell-cell adhesion. Copyright © 2017 Elsevier B.V. All rights reserved.

Utilizing Functionalized Nano-Paterned Surfaces as a clue to Cell Metastasis in Prostate and Breast Cancer

NASA Astrophysics Data System (ADS)

Matthews, James; Bastatas, Lyndon

2012-03-01

There is a direct relation between the survival of a patient diagnosed with prostate or breast cancer and the metastatic potential of the patient's cancer. It is therefore extremely important to prognose metastatic potentials. In this study we investigated whether the behaviors of cancer cells responding to our state of the art nano-patterns differ by the metastatic potential of the cancer cells. We have used lowly (LNCaP) and highly (CL-1) metastatic human prostate cancer cells and lowly (MCF-7) and highly (MB231) metastatic breast cancer cells. A surface functionalization study was then performed first on uniform gold and glass surfaces, then on gold nano-patterned surfaces made by nano-sphere lithography using nano-spheres in diameter of 200nm to 800nm. The gold surfaces were functionalized with fibronectin (FN) and confirmed through XPS analysis. The CL-1, MCF-7, and MB231 cells show similar proliferation on all surfaces regardless of the presence of FN, whereas LNCaP show a clear preference for FN coated surfaces. The proliferation of the LNCaP was reduced when grown on finer nano-scaffolds, but the more aggressive CL-1, MB231, and MCF-7 cells show an abnormal proliferation regardless of pattern size. The difference in adhesion is intrinsic and was verified through dual fluorescent imaging. Clear co-localization of actin-vinculin were found on CL-1, MCF-7, and MB231. However LNCaP cells showed the co-localization only on the tips of the cells. These results provide vital clues to the bio-mechanical differences between the cancer cells with different metastatic potential.

Regulation of T-lymphocyte motility, adhesion and de-adhesion by a cell surface mechanism directed by low density lipoprotein receptor-related protein 1 and endogenous thrombospondin-1.

PubMed

Talme, Toomas; Bergdahl, Eva; Sundqvist, Karl-Gösta

2014-06-01

T lymphocytes are highly motile and constantly reposition themselves between a free-floating vascular state, transient adhesion and migration in tissues. The regulation behind this unique dynamic behaviour remains unclear. Here we show that T cells have a cell surface mechanism for integrated regulation of motility and adhesion and that integrin ligands and CXCL12/SDF-1 influence motility and adhesion through this mechanism. Targeting cell surface-expressed low-density lipoprotein receptor-related protein 1 (LRP1) with an antibody, or blocking transport of LRP1 to the cell surface, perturbed the cell surface distribution of endogenous thrombospondin-1 (TSP-1) while inhibiting motility and potentiating cytoplasmic spreading on intercellular adhesion molecule 1 (ICAM-1) and fibronectin. Integrin ligands and CXCL12 stimulated motility and enhanced cell surface expression of LRP1, intact TSP-1 and a 130,000 MW TSP-1 fragment while preventing formation of a de-adhesion-coupled 110 000 MW TSP-1 fragment. The appearance of the 130 000 MW TSP-1 fragment was inhibited by the antibody that targeted LRP1 expression, inhibited motility and enhanced spreading. The TSP-1 binding site in the LRP1-associated protein, calreticulin, stimulated adhesion to ICAM-1 through intact TSP-1 and CD47. Shear flow enhanced cell surface expression of intact TSP-1. Hence, chemokines and integrin ligands up-regulate a dominant motogenic pathway through LRP1 and TSP-1 cleavage and activate an associated adhesion pathway through the LRP1-calreticulin complex, intact TSP-1 and CD47. This regulation of T-cell motility and adhesion makes pro-adhesive stimuli favour motile responses, which may explain why T cells prioritize movement before permanent adhesion.

High CD4(+) T-cell surface CXCR4 density as a risk factor for R5 to X4 switch in the course of HIV-1 infection.

PubMed

Fiser, Anne-Laure; Vincent, Thierry; Brieu, Natalie; Lin, Yea-Lih; Portalès, Pierre; Mettling, Clément; Reynes, Jacques; Corbeau, Pierre

2010-12-15

For unclear reasons, about 50% of HIV-infected subjects harbour CXCR4-using (X4) viral strains in addition of CCR5-using (R5) viral strains at late stages of the disease. One hypothesis is that a low CD4(+) T-cell surface CCR5 density could facilitate the emergence of X4 strains. Alternatively, one could argue that a high CD4(+) T-cell surface CXCR4 density that is observed in individuals presenting with X4 strains, could favour R5 to X4 switch. Here, we tested both hypotheses. In vivo, we observed by quantitative flow cytometry no difference in CD4(+) T-cell surface CCR5 densities between patients with or without X4 strains. In the course of an in vitro R5 infection, the delay of emergence of X4 mutants was similar between cells expressing 2 distinct cell surface CCR5 densities, but shorter (12 ± 0 days and 21 ± 0 days, respectively, P = 0.01) in cells expressing a high surface CXCR4 density as compared with cells with a low surface CXCR4 density. These data argue for a role of CXCR4 density, but not of CCR5 density, in the emergence of X4 strains. They are reassuring concerning the risk of inducing an R5 to X4 switch using CCR5 antagonists to treat HIV infection.

Molecular cloning and chromosomal mapping of bone marrow stromal cell surface gene, BST2, that may be involved in pre-B-cell growth

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

Ishikawa, Jun; Kaisho, Tsuneyasu; Tomizawa, Hitoshi

1995-04-10

Bone marrow stromal cells regulate B-cell growth and development through their surface molecules and cytokines. In this study, we generated a mAb, RS38, that recognized a novel human membrane protein, BST-2, expressed on bone marrow stromal cell lines and synovial cell lines. We cloned a cDNA encoding BST-2 from a rheumatoid arthritis-derived synovial cell line. BST-2 is a 30- to 36-kDa type II transmembrane protein, consisting of 180 amino acids. The BST-2 gene (HGMW-approved symbol BST2) is located on chromosome 19p13.2. BST-2 is expressed not only on certain bone marrow stromal cell lines but also on various normal tissues, althoughmore » its expression pattern is different from that of another bone marrow stromal cell surface molecule, BST-1. BST-2 surface expression on fibroblast cell lines facilitated the stromal cell-dependent growth of a murine bone marrow-derived pre-B-cell line, DW34. The results suggest that BST-2 may be involved in pre-B-cell growth. 45 refs., 7 figs., 2 tabs.« less

Isolation of major pancreatic cell types and long-term culture-initiating cells using novel human surface markers.

PubMed

Dorrell, Craig; Abraham, Stephanie L; Lanxon-Cookson, Kelsea M; Canaday, Pamela S; Streeter, Philip R; Grompe, Markus

2008-09-01

We have developed a novel panel of cell-surface markers for the isolation and study of all major cell types of the human pancreas. Hybridomas were selected after subtractive immunization of Balb/C mice with intact or dissociated human islets and assessed for cell-type specificity and cell-surface reactivity by immunohistochemistry and flow cytometry. Antibodies were identified by specific binding of surface antigens on islet (panendocrine or alpha-specific) and nonislet pancreatic cell subsets (exocrine and duct). These antibodies were used individually or in combination to isolate populations of alpha, beta, exocrine, or duct cells from primary human pancreas by FACS and to characterize the detailed cell composition of human islet preparations. They were also employed to show that human islet expansion cultures originated from nonendocrine cells and that insulin expression levels could be increased to up to 1% of normal islet cells by subpopulation sorting and overexpression of the transcription factors Pdx-1 and ngn3, an improvement over previous results with this culture system. These methods permit the analysis and isolation of functionally distinct pancreatic cell populations with potential for cell therapy.

Effects of Corroded and Non-Corroded Biodegradable Mg and Mg Alloys on Viability, Morphology and Differentiation of MC3T3-E1 Cells Elicited by Direct Cell/Material Interaction

PubMed Central

Mostofi, Sepideh; Bonyadi Rad, Ehsan; Wiltsche, Helmar; Fasching, Ulrike; Szakacs, Gabor; Ramskogler, Claudia; Srinivasaiah, Sriveena; Ueçal, Muammer; Willumeit, Regine; Weinberg, Annelie-Martina; Schaefer, Ute

2016-01-01

This study investigated the effect of biodegradable Mg and Mg alloys on selected properties of MC3T3-E1 cells elicited by direct cell/material interaction. The chemical composition and morphology of the surface of Mg and Mg based alloys (Mg2Ag and Mg10Gd) were analysed by scanning electron microscopy (SEM) and EDX, following corrosion in cell culture medium for 1, 2, 3 and 8 days. The most pronounced difference in surface morphology, namely crystal formation, was observed when Pure Mg and Mg2Ag were immersed in cell medium for 8 days, and was associated with an increase in atomic % of oxygen and a decrease of surface calcium and phosphorous. Crystal formation on the surface of Mg10Gd was, in contrast, negligible at all time points. Time-dependent changes in oxygen, calcium and phosphorous surface content were furthermore not observed for Mg10Gd. MC3T3-E1 cell viability was reduced by culture on the surfaces of corroded Mg, Mg2Ag and Mg10Gd in a corrosion time-independent manner. Cells did not survive when cultured on 3 day pre-corroded Pure Mg and Mg2Ag, indicating crystal formation to be particular detrimental in this regard. Cell viability was not affected when cells were cultured on non-corroded Mg and Mg alloys for up to 12 days. These results suggest that corrosion associated changes in surface morphology and chemical composition significantly hamper cell viability and, thus, that non-corroded surfaces are more conducive to cell survival. An analysis of the differentiation potential of MC3T3-E1 cells cultured on non-corroded samples based on measurement of Collagen I and Runx2 expression, revealed a down-regulation of these markers within the first 6 days following cell seeding on all samples, despite persistent survival and proliferation. Cells cultured on Mg10Gd, however, exhibited a pronounced upregulation of collagen I and Runx2 between days 8 and 12, indicating an enhancement of osteointegration by this alloy that could be valuable for in vivo orthopedic applications. PMID:27459513

Signal peptide cleavage is essential for surface expression of a regulatory T cell surface protein, leucine rich repeat containing 32 (LRRC32)

PubMed Central

2011-01-01

Background Elevated numbers of regulatory T cells (Tregs) have been implicated in certain cancers. Depletion of Tregs has been shown to increase anti-tumor immunity. Tregs also play a critical role in the suppression of autoimmune responses. The study of Tregs has been hampered by a lack of adequate surface markers. Leucine Rich Repeat Containing 32 (LRRC32), also known as Glycoprotein A Repetitions Predominant (GARP), has been postulated as a novel surface marker of activated Tregs. However, there is limited information regarding the processing of LRRC32 or the regulatory phenotype and functional activity of Tregs expressing LRRC32. Results Using naturally-occurring freshly isolated Tregs, we demonstrate that low levels of LRRC32 are present intracellularly prior to activation and that freshly isolated LRRC32+ Tregs are distinct from LRRC32- Tregs with respect to the expression of surface CD62L. Using LRRC32 transfectants of HEK cells, we demonstrate that the N-terminus of LRRC32 is cleaved prior to expression of the protein at the cell surface. Furthermore, we demonstrate using a construct containing a deleted putative signal peptide region that the presence of a signal peptide region is critical to cell surface expression of LRRC32. Finally, mixed lymphocyte assays demonstrate that LRRC32+ Tregs are more potent suppressors than LRRC32- Tregs. Conclusions A cleaved signal peptide site in LRRC32 is necessary for surface localization of native LRRC32 following activation of naturally-occurring freshly-isolated regulatory T cells. LRRC32 expression appears to alter the surface expression of activation markers of T cells such as CD62L. LRRC32 surface expression may be useful as a marker that selects for more potent Treg populations. In summary, understanding the processing and expression of LRRC32 may provide insight into the mechanism of action of Tregs and the refinement of immunotherapeutic strategies aimed at targeting these cells. PMID:21615933

A Cleavable N-Terminal Signal Peptide Promotes Widespread Olfactory Receptor Surface Expression in HEK293T Cells

PubMed Central

Shepard, Blythe D.; Natarajan, Niranjana; Protzko, Ryan J.; Acres, Omar W.; Pluznick, Jennifer L.

2013-01-01

Olfactory receptors (ORs) are G protein-coupled receptors that detect odorants in the olfactory epithelium, and comprise the largest gene family in the genome. Identification of OR ligands typically requires OR surface expression in heterologous cells; however, ORs rarely traffic to the cell surface when exogenously expressed. Therefore, most ORs are orphan receptors with no known ligands. To date, studies have utilized non-cleavable rhodopsin (Rho) tags and/or chaperones (i.e. Receptor Transporting Protein, RTP1S, Ric8b and Gαolf) to improve surface expression. However, even with these tools, many ORs still fail to reach the cell surface. We used a test set of fifteen ORs to examine the effect of a cleavable leucine-rich signal peptide sequence (Lucy tag) on OR surface expression in HEK293T cells. We report here that the addition of the Lucy tag to the N-terminus increases the number of ORs reaching the cell surface to 7 of the 15 ORs (as compared to 3/15 without Rho or Lucy tags). Moreover, when ORs tagged with both Lucy and Rho were co-expressed with previously reported chaperones (RTP1S, Ric8b and Gαolf), we observed surface expression for all 15 receptors examined. In fact, two-thirds of Lucy-tagged ORs are able to reach the cell surface synergistically with chaperones even when the Rho tag is removed (10/15 ORs), allowing for the potential assessment of OR function with only an 8-amino acid Flag tag on the mature protein. As expected for a signal peptide, the Lucy tag was cleaved from the mature protein and did not alter OR-ligand binding and signaling. Our studies demonstrate that widespread surface expression of ORs can be achieved in HEK293T cells, providing promise for future large-scale deorphanization studies. PMID:23840901

The chemotaxis-like Che1 pathway has an indirect role in adhesive cell properties of Azospirillum brasilense.

PubMed

Siuti, Piro; Green, Calvin; Edwards, Amanda Nicole; Doktycz, Mitchel J; Alexandre, Gladys

2011-10-01

The Azospirillum brasilense chemotaxis-like Che1 signal transduction pathway was recently shown to modulate changes in adhesive cell surface properties that, in turn, affect cell-to-cell aggregation and flocculation behaviors rather than flagellar-mediated chemotaxis. Attachment to surfaces and root colonization may be functions related to flocculation. Here, the conditions under which A. brasilense wild-type Sp7 and che1 mutant strains attach to abiotic and biotic surfaces were examined using in vitro attachment and biofilm assays combined with atomic force microscopy and confocal microscopy. The nitrogen source available for growth is found to be a major modulator of surface attachment by A. brasilense and could be promoted in vitro by lectins, suggesting that it depends on interaction with surface-exposed residues within the extracellular matrix of cells. However, Che1-dependent signaling is shown to contribute indirectly to surface attachment, indicating that distinct mechanisms are likely underlying flocculation and attachment to surfaces in A. brasilense. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Polydopamine-mediated surface modification of scaffold materials for human neural stem cell engineering.

PubMed

Yang, Kisuk; Lee, Jung Seung; Kim, Jin; Lee, Yu Bin; Shin, Heungsoo; Um, Soong Ho; Kim, Jeong Beom; Park, Kook In; Lee, Haeshin; Cho, Seung-Woo

2012-10-01

Surface modification of tissue engineering scaffolds and substrates is required for improving the efficacy of stem cell therapy by generating physicochemical stimulation promoting proliferation and differentiation of stem cells. However, typical surface modification methods including chemical conjugation or physical absorption have several limitations such as multistep, complicated procedures, surface denaturation, batch-to-batch inconsistencies, and low surface conjugation efficiency. In this study, we report a mussel-inspired, biomimetic approach to surface modification for efficient and reliable manipulation of human neural stem cell (NSC) differentiation and proliferation. Our study demonstrates that polydopamine coating facilitates highly efficient, simple immobilization of neurotrophic growth factors and adhesion peptides onto polymer substrates. The growth factor or peptide-immobilized substrates greatly enhance differentiation and proliferation of human NSCs (human fetal brain-derived NSCs and human induced pluripotent stem cell-derived NSCs) at a level comparable or greater than currently available animal-derived coating materials (Matrigel) with safety issues. Therefore, polydopamine-mediated surface modification can provide a versatile platform technology for developing chemically defined, safe, functional substrates and scaffolds for therapeutic applications of human NSCs. Copyright © 2012 Elsevier Ltd. All rights reserved.

Method of making a back contacted solar cell

DOEpatents

Gee, James M.

1995-01-01

A back-contacted solar cell having laser-drilled vias connecting the front-surface carrier-collector junction to an electrode grid on the back surface. The structure may also include a rear surface carrier-collector junction connected to the same grid. The substrate is connected to a second grid which is interdigitated with the first. Both grids are configured for easy series connection with neighboring cells. Several processes are disclosed to produce the cell.

Dendritic Cell-Based Genetic Immunotherapy for Ovarian Cancer

DTIC Science & Technology

2008-12-01

transduction of dendritic cells (DCs) is inefficient because of the lack of the primary Ad receptor, CAR. CD40 is a surface marker expressed by DCs that...ligands or antibodies that can bind to the cell surface markers expressed by DCs. The tumor antigen or peptides are linked to the ligands...thus pose the risk of insertional mutagenesis and oncogenesis. The various cell- surface markers that have been exploited for targeting DCs have

Cell Adhesion on Surface-Functionalized Magnesium.

PubMed

Wagener, Victoria; Schilling, Achim; Mainka, Astrid; Hennig, Diana; Gerum, Richard; Kelch, Marie-Luise; Keim, Simon; Fabry, Ben; Virtanen, Sannakaisa

2016-05-18

The biocompatibility of commercially pure magnesium-based (cp Mg) biodegradable implants is compromised of strong hydrogen evolution and surface alkalization due to high initial corrosion rates of cp Mg in the physiological environment. To mitigate this problem, the addition of corrosion-retarding alloying elements or coating of implant surfaces has been suggested. In the following work, we explored the effect of organic coatings on long-term cell growth. cp Mg was coated with aminopropyltriehtoxysilane + vitamin C (AV), carbonyldiimidazole (CDI), or stearic acid (SA). All three coatings have been previously suggested to reduce initial corrosion and to enhance protein adsorption and hence cell adhesion on magnesium surfaces. Endothelial cells (DH1+/+) and osteosarcoma cells (MG63) were cultured on coated samples for up to 20 days. To quantify Mg corrosion, electrochemical impedance spectroscopy (EIS) was measured after 1, 3, and 5 days of cell culture. We also investigated the speed of initial cell spreading after seeding using fluorescently labeled fibroblasts (NIH/3T3). Hydrogen evolution after contact with cell culture medium was markedly decreased on AV- and SA-coated Mg compared to uncoated Mg. These coatings also showed improved cell adhesion and spreading after 24 h of culture comparable to tissue-treated plastic surfaces. On AV-coated cp Mg, a confluent layer of endothelial cells formed after 5 days and remained intact for up to 20 days. Together, these data demonstrate that surface coating with AV is a viable strategy for improving long-term biocompatibility of cp Mg-based implants. EIS measurements confirmed that the presence of a confluent cell layer increased the corrosion resistance.

Polymer-Based Surfaces Designed to Reduce Biofilm Formation: From Antimicrobial Polymers to Strategies for Long-Term Applications.

PubMed

Riga, Esther K; Vöhringer, Maria; Widyaya, Vania Tanda; Lienkamp, Karen

2017-10-01

Contact-active antimicrobial polymer surfaces bear cationic charges and kill or deactivate bacteria by interaction with the negatively charged parts of their cell envelope (lipopolysaccharides, peptidoglycan, and membrane lipids). The exact mechanism of this interaction is still under debate. While cationic antimicrobial polymer surfaces can be very useful for short-term applications, they lose their activity once they are contaminated by a sufficiently thick layer of adhering biomolecules or bacterial cell debris. This layer shields incoming bacteria from the antimicrobially active cationic surface moieties. Besides discussing antimicrobial surfaces, this feature article focuses on recent strategies that were developed to overcome the contamination problem. This includes bifunctional materials with simultaneously presented antimicrobial and protein-repellent moieties; polymer surfaces that can be switched from an antimicrobial, cell-attractive to a cell-repellent state; polymer surfaces that can be regenerated by enzyme action; degradable antimicrobial polymers; and antimicrobial polymer surfaces with removable top layers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fluorogenic Green-Inside Red-Outside (GIRO) Labeling Approach Reveals Adenylyl Cyclase-Dependent Control of BKα Surface Expression

PubMed Central

2015-01-01

The regulation of surface levels of protein is critical for proper cell function and influences properties including cell adhesion, ion channel contributions to current flux, and the sensitivity of surface receptors to ligands. Here we demonstrate a two-color labeling system in live cells using a single fluorogen activating peptide (FAP) based fusion tag, which enables the rapid and simultaneous quantification of surface and internal proteins. In the nervous system, BK channels can regulate neural excitability and neurotransmitter release, and the surface trafficking of BK channels can be modulated by signaling cascades and assembly with accessory proteins. Using this labeling approach, we examine the dynamics of BK channel surface expression in HEK293 cells. Surface pools of the pore-forming BKα subunit were stable, exhibiting a plasma membrane half-life of >10 h. Long-term activation of adenylyl cyclase by forskolin reduced BKα surface levels by 30%, an effect that could not be attributed to increased bulk endocytosis of plasma membrane proteins. This labeling approach is compatible with microscopic imaging and flow cytometry, providing a solid platform for examining protein trafficking in living cells. PMID:26301573

Particles induced surface nanoroughness of titanium surface and its influence on adhesion of osteoblast-like MG-63 cells

NASA Astrophysics Data System (ADS)

Solař, P.; Kylián, O.; Marek, A.; Vandrovcová, M.; Bačáková, L.; Hanuš, J.; Vyskočil, J.; Slavínská, D.; Biederman, H.

2015-01-01

Titanium is one of the most common materials employed for production of implants, which is due to its good biocompatibility. However, the colonization of titanium surface by osteoblast cells may be influenced by its roughness and therefore precise control of roughness of titanium surface as well as identification of its optimal value for growth of cells is of high importance. In this study the nanorough titanium surfaces were prepared on polished disks of TiAlV by two step method of deposition. In the first step TiAlV were coated by nanoparticles generated by gas aggregation sources. Such prepared films of nanoparticles were subsequently covered with a titanium overlayer. Different values of surface roughness in the range 1-100 nm were achieved by variation of the size and number of the nanoparticles. Such prepared surfaces were subsequently used for investigation of influence of roughness of titanium surfaces on the adhesion of human osteoblast-like MG-63 cells. It was found out that 7 days after seeding the highest number of adhering cells was observed for samples with root-mean-square roughness of 30 nm.

A rapid live-cell ELISA for characterizing antibodies against cell surface antigens of Chlamydomonas reinhardtii and its use in isolating algae from natural environments with related cell wall components.

PubMed

Jiang, Wenzhi; Cossey, Sarah; Rosenberg, Julian N; Oyler, George A; Olson, Bradley J S C; Weeks, Donald P

2014-09-25

Cell walls are essential for most bacteria, archaea, fungi, algae and land plants to provide shape, structural integrity and protection from numerous biotic and abiotic environmental factors. In the case of eukaryotic algae, relatively little is known of the composition, structure or mechanisms of assembly of cell walls in individual species or between species and how these differences enable algae to inhabit a great diversity of environments. In this paper we describe the use of camelid antibody fragments (VHHs) and a streamlined ELISA assay as powerful new tools for obtaining mono-specific reagents for detecting individual algal cell wall components and for isolating algae that share a particular cell surface component. To develop new microalgal bioprospecting tools to aid in the search of environmental samples for algae that share similar cell wall and cell surface components, we have produced single-chain camelid antibodies raised against cell surface components of the single-cell alga, Chlamydomonas reinhardtii. We have cloned the variable-region domains (VHHs) from the camelid heavy-chain-only antibodies and overproduced tagged versions of these monoclonal-like antibodies in E. coli. Using these VHHs, we have developed an accurate, facile, low cost ELISA that uses live cells as a source of antigens in their native conformation and that requires less than 90 minutes to perform. This ELISA technique was demonstrated to be as accurate as standard ELISAs that employ proteins from cell lysates and that generally require >24 hours to complete. Among the cloned VHHs, VHH B11, exhibited the highest affinity (EC50 < 1 nM) for the C. reinhardtii cell surface. The live-cell ELISA procedure was employed to detect algae sharing cell surface components with C. reinhardtii in water samples from natural environments. In addition, mCherry-tagged VHH B11 was used along with fluorescence activated cell sorting (FACS) to select individual axenic isolates of presumed wild relatives of C. reinhardtii and other Chlorphyceae from the same environmental samples. Camelid antibody VHH domains provide a highly specific tool for detection of individual cell wall components of algae and for allowing the selection of algae that share a particular cell surface molecule from diverse ecosystems.

Antibody binding to neuronal surface in Sydenham chorea, but not in PANDAS or Tourette syndrome

PubMed Central

Merheb, V.; Ding, A.; Murphy, T.; Dale, R.C.

2011-01-01

Objective: To test the hypothesis that Sydenham chorea (SC) immunoglobulin G (IgG) autoantibodies bind to specific neuronal surface proteins, whereas IgG from patients with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) or Tourette syndrome (TS) do not bind to neuronal surface proteins. Methods: We used live differentiated SH-SY5Y cells, which have neuronal and dopaminergic characteristics. Using flow cytometry, we measured serum IgG cell surface binding in patients with SC (n = 11), PANDAS (n = 12), and TS (n = 11), and compared the findings to healthy controls (n = 11) and other neurologic controls (n = 11). In order to determine the specificity of binding to neuronal antigens, we also used a non-neuronal cell line, HEK 293. Results: The mean IgG cell surface binding was significantly higher in the SC group compared to all other groups (p < 0.001). By contrast, there was no difference between the PANDAS or TS groups and the controls. Using the non-neuronal HEK-293 cells, there was no significant difference in IgG cell surface binding between any groups. Conclusions: Serum autoantibodies that bind to neuronal cell surface antigens are present in SC, but not in PANDAS or TS. These findings strengthen the hypothesis that SC is due to a pathogenic autoantibody, but weaken the autoantibody hypothesis in PANDAS and TS. PMID:21411742

Antibody binding to neuronal surface in Sydenham chorea, but not in PANDAS or Tourette syndrome.

PubMed

Brilot, F; Merheb, V; Ding, A; Murphy, T; Dale, R C

2011-04-26

To test the hypothesis that Sydenham chorea (SC) immunoglobulin G (IgG) autoantibodies bind to specific neuronal surface proteins, whereas IgG from patients with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) or Tourette syndrome (TS) do not bind to neuronal surface proteins. We used live differentiated SH-SY5Y cells, which have neuronal and dopaminergic characteristics. Using flow cytometry, we measured serum IgG cell surface binding in patients with SC (n = 11), PANDAS (n = 12), and TS (n = 11), and compared the findings to healthy controls (n = 11) and other neurologic controls (n = 11). In order to determine the specificity of binding to neuronal antigens, we also used a non-neuronal cell line, HEK 293. The mean IgG cell surface binding was significantly higher in the SC group compared to all other groups (p < 0.001). By contrast, there was no difference between the PANDAS or TS groups and the controls. Using the non-neuronal HEK-293 cells, there was no significant difference in IgG cell surface binding between any groups. Serum autoantibodies that bind to neuronal cell surface antigens are present in SC, but not in PANDAS or TS. These findings strengthen the hypothesis that SC is due to a pathogenic autoantibody, but weaken the autoantibody hypothesis in PANDAS and TS.

DAP12 impacts trafficking and surface stability of killer immunoglobulin-like receptors on natural killer cells

PubMed Central

Mulrooney, Tiernan J.; Posch, Phillip E.; Hurley, Carolyn Katovich

2013-01-01

KIR aid in the regulation of NK cell activity. In this study, the effect of the interaction between the KIR2DS and their adapter, DAP12, was investigated beyond the previously defined signaling function. Flow cytometry analysis showed enhanced KIR2DS surface expression on NKL cells when cotransfected with DAP12. Conversely, KIR2DS4 surface expression on primary cells was decreased when the cells were treated with DAP12-specific siRNA. Treatment of the KIR2DS and DAP12-transfected cells with CHX or BFA repressed KIR2DS surface expression, revealing a role for DAP12 in trafficking newly synthesized KIR to the cell surface. Immunoprecipitation of DAP12 revealed an interaction of DAP12 with an immature isoform of KIR2DS, indicating that the interaction likely initiates within the ER. An internalization assay demonstrated a significant impact of DAP12 on KIR2DS surface stability. Confocal microscopy showed that internalized KIR2DS molecules are recruited to lysosomal compartments independent of DAP12 expression. Our results suggest that in vivo conditions that adversely affect DAP12 expression will indirectly reduce surface expression and stability of KIR2DS. These effects could significantly impact ligand recognition and strength of signaling through KIR2DS molecules. PMID:23715743

DEVELOPMENT OF A MODEL TO INVESTIGATE RED BLOOD CELL SURFACE CHARACTERISTICS AFTER CRYOPRESERVATION.

PubMed

Gordiyenko, O I; Anikieieva, M O; Rozanova, S L; Kovalenko, S Ye; Kovalenkol, I F; Gordiyenko, E O

2015-01-01

Maintaining cell surface properties after freezing and thawing, characterized in particular by the surface potential and associated with it cell ability to intercellular adhesion, could be used as a characteristic of successful cryopreservation. This study was conducted to research applying different erythrocytes freezing modes and analyses the regimes cryopreservation effect on the cell surface charge and adhesion to microorganisms. Human erythrocytes frozen by three modes. In order to determine adhesion index was used dried bacterial cells of S. thermophilus. The surface charge of erythrocytes was evaluated using Alcian blue cationic dye. The results showed the significant decrease in the lactobacillus adhesion to erythrocytes frozen glycerol and 1,2-propanediol. After erythrocytes were freezen with glycerol and 1,2-propanediol, the cationic dye binding to erythrocytes significantly reduced. AB binding to erythrocytes frozen with PEG-1500 does not differ from control data. Erythrocytes frozen with PEG-1500 mantained surface properties after thawing better, compared to erythrocytes cryopreserved by other methods.

Atomic force microscopy recognition of protein A on Staphylococcus aureus cell surfaces by labelling with IgG-Au conjugates.

PubMed

Tatlybaeva, Elena B; Nikiyan, Hike N; Vasilchenko, Alexey S; Deryabin, Dmitri G

2013-01-01

The labelling of functional molecules on the surface of bacterial cells is one way to recognize the bacteria. In this work, we have developed a method for the selective labelling of protein A on the cell surfaces of Staphylococcus aureus by using nanosized immunogold conjugates as cell-surface markers for atomic force microscopy (AFM). The use of 30-nm size Au nanoparticles conjugated with immunoglobulin G (IgG) allowed the visualization, localization and distribution of protein A-IgG complexes on the surface of S. aureus. The selectivity of the labelling method was confirmed in mixtures of S. aureus with Bacillus licheniformis cells, which differed by size and shape and had no IgG receptors on the surface. A preferential binding of the IgG-Au conjugates to S. aureus was obtained. Thus, this novel approach allows the identification of protein A and other IgG receptor-bearing bacteria, which is useful for AFM indication of pathogenic microorganisms in poly-component associations.

Viability and proliferation of endothelial cells upon exposure to GaN nanoparticles.

PubMed

Braniste, Tudor; Tiginyanu, Ion; Horvath, Tibor; Raevschi, Simion; Cebotari, Serghei; Lux, Marco; Haverich, Axel; Hilfiker, Andres

2016-01-01

Nanotechnology is a rapidly growing and promising field of interest in medicine; however, nanoparticle-cell interactions are not yet fully understood. The goal of this work was to examine the interaction between endothelial cells and gallium nitride (GaN) semiconductor nanoparticles. Cellular viability, adhesion, proliferation, and uptake of nanoparticles by endothelial cells were investigated. The effect of free GaN nanoparticles versus the effect of growing endothelial cells on GaN functionalized surfaces was examined. To functionalize surfaces with GaN, GaN nanoparticles were synthesized on a sacrificial layer of zinc oxide (ZnO) nanoparticles using hydride vapor phase epitaxy. The uptake of GaN nanoparticles by porcine endothelial cells was strongly dependent upon whether they were fixed to the substrate surface or free floating in the medium. The endothelial cells grown on surfaces functionalized with GaN nanoparticles demonstrated excellent adhesion and proliferation, suggesting good biocompatibility of the nanostructured GaN.

Non-Genomic Estrogen Regulation of Ion Transport and Airway Surface Liquid Dynamics in Cystic Fibrosis Bronchial Epithelium

PubMed Central

Saint-Criq, Vinciane; Kim, Sung Hoon; Katzenellenbogen, John A.; Harvey, Brian J.

2013-01-01

Male cystic fibrosis (CF) patients survive longer than females and lung exacerbations in CF females vary during the estrous cycle. Estrogen has been reported to reduce the height of the airway surface liquid (ASL) in female CF bronchial epithelium. Here we investigated the effect of 17β-estradiol on the airway surface liquid height and ion transport in normal (NuLi-1) and CF (CuFi-1) bronchial epithelial monolayers. Live cell imaging using confocal microscopy revealed that airway surface liquid height was significantly higher in the non-CF cells compared to the CF cells. 17β-estradiol (0.1–10 nM) reduced the airway surface liquid height in non-CF and CF cells after 30 min treatment. Treatment with the nuclear-impeded Estrogen Dendrimer Conjugate mimicked the effect of free estrogen by reducing significantly the airway surface liquid height in CF and non-CF cells. Inhibition of chloride transport or basolateral potassium recycling decreased the airway surface liquid height and 17β-estradiol had no additive effect in the presence of these ion transporter inhibitors. 17β-estradiol decreased bumetanide-sensitive transepithelial short-circuit current in non-CF cells and prevented the forskolin-induced increase in ASL height. 17β-estradiol stimulated an amiloride-sensitive transepithelial current and increased ouabain-sensitive basolateral short-circuit current in CF cells. 17β-estradiol increased PKCδ activity in CF and non-CF cells. These results demonstrate that estrogen dehydrates CF and non-CF ASL, and these responses to 17β-estradiol are non-genomic rather than involving the classical nuclear estrogen receptor pathway. 17β-estradiol acts on the airway surface liquid by inhibiting cAMP-mediated chloride secretion in non-CF cells and increasing sodium absorption via the stimulation of PKCδ, ENaC and the Na+/K+ATPase in CF cells. PMID:24223826

Cell surface retention sequence binding protein-1 interacts with the v-sis gene product and platelet-derived growth factor beta-type receptor in simian sarcoma virus-transformed cells.

PubMed

Boensch, C; Huang, S S; Connolly, D T; Huang, J S

1999-04-09

The cell surface retention sequence (CRS) binding protein-1 (CRSBP-1) is a newly identified membrane glycoprotein which is hypothesized to be responsible for cell surface retention of the oncogene v-sis and c-sis gene products and other secretory proteins containing CRSs. In simian sarcoma virus-transformed NIH 3T3 cells (SSV-NIH 3T3 cells), a fraction of CRSBP-1 was demonstrated at the cell surface and underwent internalization/recycling as revealed by cell surface 125I labeling and its resistance/sensitivity to trypsin digestion. However, the majority of CRSBP-1 was localized in intracellular compartments as evidenced by the resistance of most of the 35S-metabolically labeled CRSBP-1 to trypsin digestion, and by indirect immunofluorescent staining. CRSBP-1 appeared to form complexes with proteolytically processed forms (generated at and/or after the trans-Golgi network) of the v-sis gene product and with a approximately 140-kDa proteolytically cleaved form of the platelet-derived growth factor (PDGF) beta-type receptor, as demonstrated by metabolic labeling and co-immunoprecipitation. CRSBP-1, like the v-sis gene product and PDGF beta-type receptor, underwent rapid turnover which was blocked in the presence of 100 microM suramin. In normal and other transformed NIH 3T3 cells, CRSBP-1 was relatively stable and did not undergo rapid turnover and internalization/recycling at the cell surface. These results suggest that in SSV-NIH 3T3 cells, CRSBP-1 interacts with and forms ternary and binary complexes with the newly synthesized v-sis gene product and PDGF beta-type receptor at the trans-Golgi network and that the stable binary (CRSBP-1.v-sis gene product) complex is transported to the cell surface where it presents the v-sis gene product to unoccupied PDGF beta-type receptors during internalization/recycling.

The levels and kinetics of oxygen tension detectable at the surface of human dermal fibroblast cultures.

PubMed

Tokuda, Y; Crane, S; Yamaguchi, Y; Zhou, L; Falanga, V

2000-03-01

Low oxygen tension has recently been shown to stimulate cell growth and clonal expansion, as well as synthesis and transcription of certain growth factors and extracellular matrix components. These results have been obtained by exposing cell cultures to a hypoxic environment. Using an oxygen probe, we have now studied how experimental conditions affect the oxygen tension detectable at the cell surface. Dissolved oxygen tension was directly related to the height of the medium above the cell surface (r = 0.8793, P = 0.021), but was constant when no cells were present in the flask (r = -0. 9732, P = 0.001). In both human dermal fibroblasts and NIH/3T3 cultures, oxygen tension decreased linearly as cell density increased (r = -0.835, P < 0.0001; r = -0.916, P < 0.0001, respectively). When human dermal fibroblasts were exposed to 2% O(2), maximum hypoxic levels (0 mmHg) were achieved within approximately 15 min, and the recovery time was within a similar time frame. The addition of rotenone, an inhibitor of cellular respiration, blocked this decrease in oxygen tension at the cell surface, suggesting that cellular consumption of oxygen is responsible for the decline. Finally, we examined the cell-surface oxygen tension in control and acutely wounded human skin equivalents (HSE), consisting of a keratinocyte layer over a type I collagen matrix containing fibroblasts. We found that oxygen tension dropped significantly (P < 0.0001) in acutely wounded areas of HSE as compared to unwounded areas of HSE and that this drop was prevented by the addition of mitomycin C. These results indicate that cell-surface oxygen tension is indirectly related to cell density, and that the amount of detectable oxygen at the cell surface is a function of cell density, the oxygen tension in the incubator, and increased cellular activity, as occurs after injury. Copyright 2000 Wiley-Liss, Inc.

Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization.

PubMed

Han, Guang; Müller, Werner E G; Wang, Xiaohong; Lilja, Louise; Shen, Zhijian

2015-02-01

Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 μm. An additional mesoporous titania top layer following the contour of the macropores, of 100-200 nm thickness and with a pore diameter of 10nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography. Copyright © 2014 Elsevier B.V. All rights reserved.

Engineering micropatterned surfaces to modulate the function of vascular stem cells

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

Li, Jennifer; Wu, Michelle; Chu, Julia

2014-02-21

Highlights: • We examine vascular stem cell function on microgrooved and micropost patterned polymer substrates. • 10 μm microgrooved surfaces significantly lower VSC proliferation but do not modulate calcified matrix deposition. • Micropost surfaces significantly lower VSC proliferation and decrease calcified matrix deposition. - Abstract: Multipotent vascular stem cells have been implicated in vascular disease and in tissue remodeling post therapeutic intervention. Hyper-proliferation and calcified extracellular matrix deposition of VSC cause blood vessel narrowing and plaque hardening thereby increasing the risk of myocardial infarct. In this study, to optimize the surface design of vascular implants, we determined whether micropatterned polymermore » surfaces can modulate VSC differentiation and calcified matrix deposition. Undifferentiated rat VSC were cultured on microgrooved surfaces of varied groove widths, and on micropost surfaces. 10 μm microgrooved surfaces elongated VSC and decreased cell proliferation. However, microgrooved surfaces did not attenuate calcified extracellular matrix deposition by VSC cultured in osteogenic media conditions. In contrast, VSC cultured on micropost surfaces assumed a dendritic morphology, were significantly less proliferative, and deposited minimal calcified extracellular matrix. These results have significant implications for optimizing the design of cardiovascular implant surfaces.« less

Theory of back-surface-field solar cells

NASA Technical Reports Server (NTRS)

Vonroos, O.

1979-01-01

Report describes simple concise theory of back-surface-field (BSF) solar cells (npp + junctions) based on Shockley's depletion-layer approximation and cites superiority of two-junction devices over conventional unijunction cells.

Maintaining the pluripotency of mouse embryonic stem cells on gold nanoparticle layers with nanoscale but not microscale surface roughness

NASA Astrophysics Data System (ADS)

Lyu, Zhonglin; Wang, Hongwei; Wang, Yanyun; Ding, Kaiguo; Liu, Huan; Yuan, Lin; Shi, Xiujuan; Wang, Mengmeng; Wang, Yanwei; Chen, Hong

2014-05-01

Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction.Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01540a

Carbon nanotube-coating accelerated cell adhesion and proliferation on poly (L-lactide)

NASA Astrophysics Data System (ADS)

Hirata, Eri; Akasaka, Tsukasa; Uo, Motohiro; Takita, Hiroko; Watari, Fumio; Yokoyama, Atsuro

2012-12-01

The surface of a polylactic acid (PLLA) was coated multiwalled carbon nanotubes (MWCNTs) in order to improve the surface properties. In addition, its surface characteristics and cell culturing properties were examined. Whole surface of PLLA was homogeneously covered by MWCNTs maintained a unique tubular structure. MWCNT-coated PLLA showed remarkable higher wettability than uncoated PLLA. Human osteosarcoma cell line (Saos2) adhered well on the CNT-coated PLLA whereas there are few cells attached on the uncoated PLLA at 2 h after seeding. The number of the cells on uncoated PLLA was still smaller than on the MWCNT-coated PLLA at 1 and 3 days. Moreover, The DNA content in the cells attached to the MWCNT-coated PLLA was significantly higher than that on the uncoated PLLA (p < 0.05) at 1 and 3 days. There was no significant difference between the scaffolds for ALP activity normalized by DNA content at both term (p > 0.1). Therefore MWCNT-coating on PLLA improved the surface wettability and initial cell attachment at early stage.

Acoustic sensors as a biophysical tool for probing cell attachment and cell/surface interactions.

PubMed

Saitakis, Michael; Gizeli, Electra

2012-02-01

Acoustic biosensors offer the possibility to analyse cell attachment and spreading. This is due to the offered speed of detection, the real-time non-invasive approach and their high sensitivity not only to mass coupling, but also to viscoelastic changes occurring close to the sensor surface. Quartz crystal microbalance (QCM) and surface acoustic wave (Love-wave) systems have been used to monitor the adhesion of animal cells to various surfaces and record the behaviour of cell layers under various conditions. The sensors detect cells mostly via their sensitivity in viscoelasticity and mechanical properties. Particularly, the QCM sensor detects cytoskeletal rearrangements caused by specific drugs affecting either actin microfilaments or microtubules. The Love-wave sensor directly measures cell/substrate bonds via acoustic damping and provides 2D kinetic and affinity parameters. Other studies have applied the QCM sensor as a diagnostic tool for leukaemia and, potentially, for chemotherapeutic agents. Acoustic sensors have also been used in the evaluation of the cytocompatibility of artificial surfaces and, in general, they have the potential to become powerful tools for even more diverse cellular analysis.

Glass matrix armor

DOEpatents

Calkins, Noel C.

1991-01-01

An armor system which utilizes glass. A plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material consisting of glass and a ceramic material and, in certain embodiments, a polymeric material. The glass may be in monolithic form or particles of ceramic may be dispersed in a glass matrix. The ceramic material may be in monolithic form or may be in the form of particles dispersed in glass or dispersed in said polymer.

Methods For Improving Polymeric Materials For Use In Solar Cell Applications

DOEpatents

Hanoka, Jack I.

2003-07-01

A method of manufacturing a solar cell module includes the use of low cost polymeric materials with improved mechanical properties. A transparent encapsulant layer is placed adjacent a rear surface of a front support layer. Interconnected solar cells are positioned adjacent a rear surface of the transparent encapsulant layer to form a solar cell assembly. A backskin layer is placed adjacent a rear surface of the solar cell assembly. At least one of the transparent encapsulant layer and the backskin layer are predisposed to electron beam radiation.

Methods For Improving Polymeric Materials For Use In Solar Cell Applications

DOEpatents

Hanoka, Jack I.

2001-11-20

A method of manufacturing a solar cell module includes the use of low cost polymeric materials with improved mechanical properties. A transparent encapsulant layer is placed adjacent a rear surface of a front support layer. Interconnected solar cells are positioned adjacent a rear surface of the transparent encapsulant layer to form a solar cell assembly. A backskin layer is placed adjacent a rear surface of the solar cell assembly. At least one of the transparent encapsulant layer and the backskin layer are predisposed to electron beam radiation.

Functional cell-surface display of a lipase-specific chaperone.

PubMed

Wilhelm, Susanne; Rosenau, Frank; Becker, Stefan; Buest, Sebastian; Hausmann, Sascha; Kolmar, Harald; Jaeger, Karl-Erich

2007-01-02

Lipases are important enzymes in biotechnology. Extracellular bacterial lipases from Pseudomonads and related species require the assistance of specific chaperones, designated "Lif" proteins (lipase specific foldases). Lifs, a unique family of steric chaperones, are anchored to the periplasmic side of the inner membrane where they convert lipases into their active conformation. We have previously shown that the autotransporter protein EstA from P. aeruginosa can be used to direct a variety of proteins to the cell surface of Escherichia coli. Here we demonstrate for the first time the functional cell-surface display of the Lif chaperone and FACS (fluorescence-activated cell sorting)-based analysis of bacterial cells that carried foldase-lipase complexes. The model Lif protein, LipH from P. aeruginosa, was displayed at the surface of E. coli cells. Surface exposed LipH was functional and efficiently refolded chemically denatured lipase. The foldase autodisplay system reported here can be used for a variety of applications including the ultrahigh-throughput screening of large libraries of foldase variants generated by directed evolution.

Sustained neurotensin exposure promotes cell surface recruitment of NTS2 receptors

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

Perron, Amelie; Sharif, Nadder; Gendron, Louis

2006-05-12

In this study, we investigated whether persistent agonist stimulation of NTS2 receptors gives rise to down-regulation, in light of reports that their activation induced long-lasting effects. To address this issue, we incubated COS-7 cells expressing the rat NTS2 with neurotensin (NT) for up to 24 h and measured resultant cell surface [{sup 125}I]-NT binding. We found that NTS2-expressing cells retained the same surface receptor density despite efficient internalization mechanisms. This preservation was neither due to NTS2 neosynthesis nor recycling since it was not blocked by cycloheximide or monensin. However, it appeared to involve translocation of spare receptors from internal stores,more » as NT induced NTS2 migration from trans-Golgi network to endosome-like structures. This stimulation-induced regulation of cell surface NTS2 receptors was even more striking in rat spinal cord neurons. Taken together, these results suggest that sustained NTS2 activation promotes recruitment of intracellular receptors to the cell surface, thereby preventing functional desensitization.« less

Cytomegalovirus immune evasion by perturbation of endosomal trafficking

PubMed Central

Lučin, Pero; Mahmutefendić, Hana; Blagojević Zagorac, Gordana; Ilić Tomaš, Maja

2015-01-01

Cytomegaloviruses (CMVs), members of the herpesvirus family, have evolved a variety of mechanisms to evade the immune response to survive in infected hosts and to establish latent infection. They effectively hide infected cells from the effector mechanisms of adaptive immunity by eliminating cellular proteins (major histocompatibility Class I and Class II molecules) from the cell surface that display viral antigens to CD8 and CD4 T lymphocytes. CMVs also successfully escape recognition and elimination of infected cells by natural killer (NK) cells, effector cells of innate immunity, either by mimicking NK cell inhibitory ligands or by downregulating NK cell-activating ligands. To accomplish these immunoevasion functions, CMVs encode several proteins that function in the biosynthetic pathway by inhibiting the assembly and trafficking of cellular proteins that participate in immune recognition and thereby, block their appearance at the cell surface. However, elimination of these proteins from the cell surface can also be achieved by perturbation of their endosomal route and subsequent relocation from the cell surface into intracellular compartments. Namely, the physiological route of every cellular protein, including immune recognition molecules, is characterized by specific features that determine its residence time at the cell surface. In this review, we summarize the current understanding of endocytic trafficking of immune recognition molecules and perturbations of the endosomal system during infection with CMVs and other members of the herpesvirus family that contribute to their immune evasion mechanisms. PMID:25263490

Combined use of atomic force microscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry for cell surface analysis.

PubMed

Dague, Etienne; Delcorte, Arnaud; Latgé, Jean-Paul; Dufrêne, Yves F

2008-04-01

Understanding the surface properties of microbial cells is a major challenge of current microbiological research and a key to efficiently exploit them in biotechnology. Here, we used three advanced surface analysis techniques with different sensitivity, probing depth, and lateral resolution, that is, in situ atomic force microscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry, to gain insight into the surface properties of the conidia of the human fungal pathogen Aspergillus fumigatus. We show that the native ultrastructure, surface protein and polysaccharide concentrations, and amino acid composition of three mutants affected in hydrophobin production are markedly different from those of the wild-type, thereby providing novel insight into the cell wall architecture of A. fumigatus. The results demonstrate the power of using multiple complementary techniques for probing microbial cell surfaces.

Lagrangian particle drift and surface deformation in a rotating wave on a free liquid surface

NASA Astrophysics Data System (ADS)

Fontana, Paul W.; Francois, Nicolas; Xia, Hua; Punzmann, Horst; Shats, Michael

2017-11-01

A nonlinear model of a rotating wave on the free surface of a liquid is presented. The flow is assumed to be inviscid and irrotational. The wave is constructed as a superposition of two perpendicular, monochromatic standing Stokes waves and is standing-wave-like, but with ``antinodes'' or cells consisting of rotating surface gradients of alternating polarity. Lagrangian fluid particle trajectories show a rotational drift about each cell in the direction of wave rotation, corresponding to a rotating Stokes drift. Each cell therefore has a circulating flow and localized angular momentum even though the Eulerian flow is irrotational. Meanwhile, the wave sets up a static displacement of the free surface, making a trough in each cell. This static surface gradient provides a centripetal force that may account for additional rotation seen in experiments.

Global transcriptomic analysis of model human cell lines exposed to surface-modified gold nanoparticles: the effect of surface chemistry

NASA Astrophysics Data System (ADS)

Grzincic, E. M.; Yang, J. A.; Drnevich, J.; Falagan-Lotsch, P.; Murphy, C. J.

2015-01-01

Gold nanoparticles (Au NPs) are attractive for biomedical applications not only for their remarkable physical properties, but also for the ease of which their surface chemistry can be manipulated. Many applications involve functionalization of the Au NP surface in order to improve biocompatibility, attach targeting ligands or carry drugs. However, changes in cells exposed to Au NPs of different surface chemistries have been observed, and little is known about how Au NPs and their surface coatings may impact cellular gene expression. The gene expression of two model human cell lines, human dermal fibroblasts (HDF) and prostate cancer cells (PC3) was interrogated by microarray analysis of over 14 000 human genes. The cell lines were exposed to four differently functionalized Au NPs: citrate, poly(allylamine hydrochloride) (PAH), and lipid coatings combined with alkanethiols or PAH. Gene functional annotation categories and weighted gene correlation network analysis were used in order to connect gene expression changes to common cellular functions and to elucidate expression patterns between Au NP samples. Coated Au NPs affect genes implicated in proliferation, angiogenesis, and metabolism in HDF cells, and inflammation, angiogenesis, proliferation apoptosis regulation, survival and invasion in PC3 cells. Subtle changes in surface chemistry, such as the initial net charge, lability of the ligand, and underlying layers greatly influence the degree of expression change and the type of cellular pathway affected.Gold nanoparticles (Au NPs) are attractive for biomedical applications not only for their remarkable physical properties, but also for the ease of which their surface chemistry can be manipulated. Many applications involve functionalization of the Au NP surface in order to improve biocompatibility, attach targeting ligands or carry drugs. However, changes in cells exposed to Au NPs of different surface chemistries have been observed, and little is known about how Au NPs and their surface coatings may impact cellular gene expression. The gene expression of two model human cell lines, human dermal fibroblasts (HDF) and prostate cancer cells (PC3) was interrogated by microarray analysis of over 14 000 human genes. The cell lines were exposed to four differently functionalized Au NPs: citrate, poly(allylamine hydrochloride) (PAH), and lipid coatings combined with alkanethiols or PAH. Gene functional annotation categories and weighted gene correlation network analysis were used in order to connect gene expression changes to common cellular functions and to elucidate expression patterns between Au NP samples. Coated Au NPs affect genes implicated in proliferation, angiogenesis, and metabolism in HDF cells, and inflammation, angiogenesis, proliferation apoptosis regulation, survival and invasion in PC3 cells. Subtle changes in surface chemistry, such as the initial net charge, lability of the ligand, and underlying layers greatly influence the degree of expression change and the type of cellular pathway affected. Electronic supplementary information (ESI) available: UV-Vis spectra of Au NPs, the most significantly changed genes of HDF cells after Au NP incubation under GO accession number GO:0007049 ``cell cycle'', detailed information about the primer/probe sets used for RT-PCR validation of results. See DOI: 10.1039/c4nr05166a

Effects of DDT and Triclosan on Tumor-cell Binding Capacity and Cell-Surface Protein Expression of Human Natural Killer Cells

PubMed Central

Hurd-Brown, Tasia; Udoji, Felicia; Martin, Tamara; Whalen, Margaret M.

2012-01-01

1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) and triclosan (TCS) are organochlorine (OC) compounds that contaminate the environment, are found in human blood, and have been shown to decrease the tumor-cell killing (lytic) function of human natural killer (NK) cells. NK cells defend against tumor cells and virally infected cells. They bind to these targets, utilizing a variety of cell surface proteins. This study examined concentrations of DDT and TCS that decrease lytic function for alteration of NK binding to tumor targets. Levels of either compound that caused loss of binding function were then examined for effects on expression of cell-surface proteins needed for binding. NK cells exposed to 2.5 μM DDT for 24 h (which caused a greater than 55% loss of lytic function) showed a decrease in NK binding function of about 22%, and a decrease in CD16 cell-surface protein of 20%. NK cells exposed to 5 μM TCS for 24 h showed a decrease in ability to bind tumor cells of 37% and a decrease in expression of CD56 of about 34%. This same treatment caused a decrease in lytic function of greater than 87%. These results indicated that only a portion of the loss of NK lytic function seen with exposures to these compounds could be accounted for by loss of binding function. They also showed that loss of binding function is accompanied by a loss cell-surface proteins important in binding function. PMID:22729613

In vitro fibroblast and pre-osteoblastic cellular responses on laser surface modified Ti-6Al-4V.

PubMed

Chikarakara, Evans; Fitzpatrick, Patricia; Moore, Eric; Levingstone, Tanya; Grehan, Laura; Higginbotham, Clement; Vázquez, Mercedes; Bagga, Komal; Naher, Sumsun; Brabazon, Dermot

2014-12-29

The success of any implant, dental or orthopaedic, is driven by the interaction of implant material with the surrounding tissue. In this context, the nature of the implant surface plays a direct role in determining the long term stability as physico-chemical properties of the surface affect cellular attachment, expression of proteins, and finally osseointegration. Thus to enhance the degree of integration of the implant into the host tissue, various surface modification techniques are employed. In this work, laser surface melting of titanium alloy Ti-6Al-4V was carried out using a CO2 laser with an argon gas atmosphere. Investigations were carried out to study the influence of laser surface modification on the biocompatibility of Ti-6Al-4V alloy implant material. Surface roughness, microhardness, and phase development were recorded. Initial knowledge of these effects on biocompatibility was gained from examination of the response of fibroblast cell lines, which was followed by examination of the response of osteoblast cell lines which is relevant to the applications of this material in bone repair. Biocompatibility with these cell lines was analysed via Resazurin cell viability assay, DNA cell attachment assay, and alamarBlue metabolic activity assay. Laser treated surfaces were found to preferentially promote cell attachment, higher levels of proliferation, and enhanced bioactivity when compared to untreated control samples. These results demonstrate the tremendous potential of this laser surface melting treatment to significantly improve the biocompatibility of titanium implants in vivo.

Investigating Evolutionary Conservation of Dendritic Cell Subset Identity and Functions

PubMed Central

Vu Manh, Thien-Phong; Bertho, Nicolas; Hosmalin, Anne; Schwartz-Cornil, Isabelle; Dalod, Marc

2015-01-01

Dendritic cells (DCs) were initially defined as mononuclear phagocytes with a dendritic morphology and an exquisite efficiency for naïve T-cell activation. DC encompass several subsets initially identified by their expression of specific cell surface molecules and later shown to excel in distinct functions and to develop under the instruction of different transcription factors or cytokines. Very few cell surface molecules are expressed in a specific manner on any immune cell type. Hence, to identify cell types, the sole use of a small number of cell surface markers in classical flow cytometry can be deceiving. Moreover, the markers currently used to define mononuclear phagocyte subsets vary depending on the tissue and animal species studied and even between laboratories. This has led to confusion in the definition of DC subset identity and in their attribution of specific functions. There is a strong need to identify a rigorous and consensus way to define mononuclear phagocyte subsets, with precise guidelines potentially applicable throughout tissues and species. We will discuss the advantages, drawbacks, and complementarities of different methodologies: cell surface phenotyping, ontogeny, functional characterization, and molecular profiling. We will advocate that gene expression profiling is a very rigorous, largely unbiased and accessible method to define the identity of mononuclear phagocyte subsets, which strengthens and refines surface phenotyping. It is uniquely powerful to yield new, experimentally testable, hypotheses on the ontogeny or functions of mononuclear phagocyte subsets, their molecular regulation, and their evolutionary conservation. We propose defining cell populations based on a combination of cell surface phenotyping, expression analysis of hallmark genes, and robust functional assays, in order to reach a consensus and integrate faster the huge but scattered knowledge accumulated by different laboratories on different cell types, organs, and species. PMID:26082777

The Cell-Surface N-Glycome of Human Embryonic Stem Cells and Differentiated Hepatic Cells thereof.

PubMed

Montacir, Houda; Freyer, Nora; Knöspel, Fanny; Urbaniak, Thomas; Dedova, Tereza; Berger, Markus; Damm, Georg; Tauber, Rudolf; Zeilinger, Katrin; Blanchard, Véronique

2017-07-04

Human embryonic stem cells (hESCs) are pluripotent stem cells that offer a wide range of applications in regenerative medicine. In addition, they have been proposed as an appropriate alternative source of hepatocytes. In this work, hESCs were differentiated into definitive endodermal cells (DECs), followed by maturation into hepatocyte-like cells (HLCs). Their cell-surface N-glycome was profiled and also compared with that of primary human hepatocytes (PHHs). Undifferentiated hESCs contained large amounts of high-mannose N-glycans. In contrast, complex-type N-glycans such as asialylated or monosialylated biantennary and triantennary N-glycans were dominant in HLCs, and fully galactosylated structures were significantly more abundant than in undifferentiated hESCs. The cell-surface N-glycosylation of PHHs was more biologically processed than that of HLCs, with bisialylated biantennary and trisialylated triantennary structures predominant. This is the first report of the cell surface N-glycome of PHHs and of HLCs being directly generated from hESCs without embryoid body formation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photofunctionalization and non-thermal plasma activation of titanium surfaces.

PubMed

Henningsen, Anders; Smeets, Ralf; Hartjen, Philip; Heinrich, Oliver; Heuberger, Roman; Heiland, Max; Precht, Clarissa; Cacaci, Claudio

2018-03-01

The aim of this study was to compare UV light and non-thermal plasma (NTP) treatment regarding the improvement of physical material characteristics and cell reaction on titanium surfaces in vitro after short-term functionalization. Moderately rough (Ra 1.8-2.0 μm) sandblasted and acid-etched titanium disks were treated by UV light (0.05 mW/cm 2 at λ = 360 nm and 2 mW/cm 2 at λ = 250 nm) or by NTP (24 W, -0.5 mbar) of argon or oxygen for 12 min each. Surface structure was investigated by scanning electron microscopy, confocal microscopy and X-ray photoelectron spectroscopy (XPS). Hydrophilicity was assessed by dynamic contact angle measurement. Cell attachment, viability, cell proliferation and cytotoxicity were assessed in vitro using murine osteoblast-like cells. UV irradiation or NTP treatment of titanium surfaces did not alter the surface structure. XPS analysis revealed a significantly increased oxidation of the surface and a decrease of carbon after the use of either method. NTP and UV light led to a significant better cell attachment of murine osteoblasts; significantly more osteoblasts grew on the treated surfaces at each time point (p < 0.001). UV light as well as NTP modified the surface of titanium and significantly improved the conditions for murine osteoblast cells in vitro. However, results indicate a slight advantage for NTP of argon and oxygen in a short time interval of surface functionalization compared to UV. UV light and NTP are able to improve surface conditions of dental implants made of titanium.

Cell behavior on gallium nitride surfaces: peptide affinity attachment versus covalent functionalization.

PubMed

Foster, Corey M; Collazo, Ramon; Sitar, Zlatko; Ivanisevic, Albena

2013-07-02

Gallium nitride is a wide band gap semiconductor that demonstrates a unique set of optical and electrical properties as well as aqueous stability and biocompatibility. This combination of properties makes gallium nitride a strong candidate for use in chemical and biological applications such as sensors and neural interfaces. Molecular modification can be used to enhance the functionality and properties of the gallium nitride surface. Here, gallium nitride surfaces were functionalized with a PC12 cell adhesion promoting peptide using covalent and affinity driven attachment methods. The covalent scheme proceeded by Grignard reaction and olefin metathesis while the affinity driven scheme utilized the recognition peptide isolated through phage display. This study shows that the method of attaching the adhesion peptide influences PC12 cell adhesion and differentiation as measured by cell density and morphological analysis. Covalent attachment promoted monolayer and dispersed cell adhesion while affinity driven attachment promoted multilayer cell agglomeration. Higher cell density was observed on surfaces modified using the recognition peptide. The results suggest that the covalent and affinity driven attachment methods are both suitable for promoting PC12 cell adhesion to the gallium nitride surface, though each method may be preferentially suited for distinct applications.

Sialyl-lactotetra, a novel cell surface marker of undifferentiated human pluripotent stem cells.

PubMed

Barone, Angela; Säljö, Karin; Benktander, John; Blomqvist, Maria; Månsson, Jan-Eric; Johansson, Bengt R; Mölne, Johan; Aspegren, Anders; Björquist, Petter; Breimer, Michael E; Teneberg, Susann

2014-07-04

Cell surface glycoconjugates are used as markers for undifferentiated pluripotent stem cells. Here, antibody binding and mass spectrometry characterization of acid glycosphingolipids isolated from a large number (1 × 10(9) cells) of human embryonic stem cell (hESC) lines allowed identification of several novel acid glycosphingolipids, like the gangliosides sialyl-lactotetraosylceramide and sialyl-globotetraosylceramide, and the sulfated glycosphingolipids sulfatide, sulf-lactosylceramide, and sulf-globopentaosylceramide. A high cell surface expression of sialyl-lactotetra on hESC and human induced pluripotent stem cells (hiPSC) was demonstrated by flow cytometry, immunohistochemistry, and electron microscopy, whereas sulfated glycosphingolipids were only found in intracellular compartments. Immunohistochemistry showed distinct cell surface anti-sialyl-lactotetra staining on all seven hESC lines and three hiPSC lines analyzed, whereas no staining of hESC-derived hepatocyte-like or cardiomyocyte-like cells was obtained. Upon differentiation of hiPSC into hepatocyte-like cells, the sialyl-lactotetra epitope was rapidly down-regulated and not detectable after 14 days. These findings identify sialyl-lactotetra as a promising marker of undifferentiated human pluripotent stem cells. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

An algorithm-based topographical biomaterials library to instruct cell fate

PubMed Central

Unadkat, Hemant V.; Hulsman, Marc; Cornelissen, Kamiel; Papenburg, Bernke J.; Truckenmüller, Roman K.; Carpenter, Anne E.; Wessling, Matthias; Post, Gerhard F.; Uetz, Marc; Reinders, Marcel J. T.; Stamatialis, Dimitrios; van Blitterswijk, Clemens A.; de Boer, Jan

2011-01-01

It is increasingly recognized that material surface topography is able to evoke specific cellular responses, endowing materials with instructive properties that were formerly reserved for growth factors. This opens the window to improve upon, in a cost-effective manner, biological performance of any surface used in the human body. Unfortunately, the interplay between surface topographies and cell behavior is complex and still incompletely understood. Rational approaches to search for bioactive surfaces will therefore omit previously unperceived interactions. Hence, in the present study, we use mathematical algorithms to design nonbiased, random surface features and produce chips of poly(lactic acid) with 2,176 different topographies. With human mesenchymal stromal cells (hMSCs) grown on the chips and using high-content imaging, we reveal unique, formerly unknown, surface topographies that are able to induce MSC proliferation or osteogenic differentiation. Moreover, we correlate parameters of the mathematical algorithms to cellular responses, which yield novel design criteria for these particular parameters. In conclusion, we demonstrate that randomized libraries of surface topographies can be broadly applied to unravel the interplay between cells and surface topography and to find improved material surfaces. PMID:21949368

Differential responses of osteoblast lineage cells to nanotopographically-modified, microroughened titanium-aluminum-vanadium alloy surfaces.

PubMed

Gittens, Rolando A; Olivares-Navarrete, Rene; McLachlan, Taylor; Cai, Ye; Hyzy, Sharon L; Schneider, Jennifer M; Schwartz, Zvi; Sandhage, Kenneth H; Boyan, Barbara D

2012-12-01

Surface structural modifications at the micrometer and nanometer scales have driven improved success rates of dental and orthopaedic implants by mimicking the hierarchical structure of bone. However, how initial osteoblast-lineage cells populating an implant surface respond to different hierarchical surface topographical cues remains to be elucidated, with bone marrow mesenchymal stem cells (MSCs) or immature osteoblasts as possible initial colonizers. Here we show that in the absence of any exogenous soluble factors, osteoblastic maturation of primary human osteoblasts (HOBs) but not osteoblastic differentiation of MSCs is strongly influenced by nanostructures superimposed onto a microrough Ti6Al4V (TiAlV) alloy. The sensitivity of osteoblasts to both surface microroughness and nanostructures led to a synergistic effect on maturation and local factor production. Osteoblastic differentiation of MSCs was sensitive to TiAlV surface microroughness with respect to production of differentiation markers, but no further enhancement was found when cultured on micro/nanostructured surfaces. Superposition of nanostructures to microroughened surfaces affected final MSC numbers and enhanced production of vascular endothelial growth factor (VEGF) but the magnitude of the response was lower than for HOB cultures. Our results suggest that the differentiation state of osteoblast-lineage cells determines the recognition of surface nanostructures and subsequent cell response, which has implications for clinical evaluation of new implant surface nanomodifications. Copyright © 2012 Elsevier Ltd. All rights reserved.

Differential Responses of Osteoblast Lineage Cells to Nanotopographically-Modified, Microroughened Titanium-Aluminum-Vanadium Alloy Surfaces

PubMed Central

Gittens, Rolando A.; Olivares-Navarrete, Rene; McLachlan, Taylor; Cai, Ye; Hyzy, Sharon L.; Schneider, Jennifer M.; Schwartz, Zvi; Sandhage, Kenneth H.; Boyan, Barbara D.

2013-01-01

Surface structural modifications at the micrometer and nanometer scales have driven improved success rates of dental and orthopaedic implants by mimicking the hierarchical structure of bone. However, how initial osteoblast-lineage cells populating an implant surface respond to different hierarchical surface topographical cues remains to be elucidated, with bone marrow mesenchymal stem cells (MSCs) or immature osteoblasts as possible initial colonizers. Here we show that in the absence of any exogenous soluble factors, osteoblastic maturation of primary human osteoblasts (HOBs) but not osteoblastic differentiation of MSCs is strongly influenced by nanostructures superimposed onto a microrough Ti6Al4V (TiAlV) alloy. The sensitivity of osteoblasts to both surface microroughness and nanostructures led to a synergistic effect on maturation and local factor production. Osteoblastic differentiation of MSCs was sensitive to TiAlV surface microroughness with respect to production of differentiation markers, but no further enhancement was found when cultured on micro/nanostructured surfaces. Superposition of nanostructures to microroughened surfaces affected final MSC numbers and enhanced production of vascular endothelial growth factor (VEGF) but the magnitude of the response was lower than for HOB cultures. Our results suggest that the differentiation state of osteoblast-lineage cells determines the recognition of surface nanostructures and subsequent cell response, which has implications for clinical evaluation of new implant surface nanomodifications. PMID:22989383

Evaluation of intranuclear BrdU detection procedures for use in multicolor flow cytometry*

PubMed Central

Rothaeusler, Kristina; Baumgarth, Nicole

2010-01-01

Background Measurement of cell proliferation via BrdU incorporation in combination with multicolor cell surface staining would facilitate studies on cell subsets that require multiple markers for their identification. However, the extent to which the often harsh cell preparation procedures required affect the staining quality of more recently developed fluorescent dyes has not been assessed. Methods Three cell preparation protocols for BrdU measurement were compared for their ability to maintain fluorescent surface staining and scatter parameters of in vivo BrdU-labeled cells by flow cytometry. A 10-color fluorescent panel was developed to test the quality of surface staining following cell treatment and the ability to perform BrdU measurements on even small B lymphocyte subsets. Results All cell preparation procedures affected the quality of fluorescent and/or scatter parameters to varying degrees. Paraformaldehyde / saponin-based procedures preserved sufficient fluorescent surface staining to determine BrdU incorporation rates among all splenic B cell subsets, including B-1a cells, which constitute roughly 0.5% of cells. Turnover rates of B-1a cells were similar to immature B cells and higher than those of the other mature B cell subsets. Conclusion Paraformaldehyde / saponin-based cell preparation procedures facilitate detailed cell turnover studies on small cell subsets in vivo, revealing new functional information on rare cell populations. PMID:16538653

A mechanistic dissection of polyethylenimine mediated transfection of CHO cells: to enhance the efficiency of recombinant DNA utilization.

PubMed

Mozley, Olivia L; Thompson, Ben C; Fernandez-Martell, Alejandro; James, David C

2014-01-01

In this study, we examine the molecular and cellular interactions that underpin efficient internalization and utilization of polyethylenimine (PEI):DNA complexes (polyplexes) by Chinese Hamster Ovary (CHO) cells. Cell surface polyplex binding and internalization was a biphasic process, consisting of an initial rapid Phase (I), lasting approximately 15 min, followed by a slower second Phase (II), saturating at approximately 240 min post transfection. The second Phase accounted for the majority (60-70%) of polyplex internalization. While cell surface heparan sulphate proteoglycans (HSPGs) were rapidly cointernalized with polyplexes during Phase I, cell surface polyplex binding was not dependent on HSPGs. However, Phase II polyplex internalization and HSPG regeneration onto the surface of trypsinized cells occurred at similar rates, suggesting that the rate of recycling of HSPG-containing membrane to the plasma membrane limits Phase II internalization rate. Under optimal transfection conditions, polyplexes had a near neutral surface charge (zeta potential) and cell surface binding was dependent on hydrophobic interactions, being significantly inhibited by both chemical sequestration of cholesterol from the plasma membrane and addition of nonionic surfactant. Induced alterations in polyplex zeta potential, using ferric (III) citrate to decrease surface charge and varying PEI:DNA ratio to increase surface charge, served to inhibit polyplex binding or reduce secreted alkaline phosphatase reporter expression and cell viability, respectively. To increase polyplex hydrophobicity and internalization an alkylated derivative of PEI, propyl-PEI, was chemically synthesized. Using Design of Experiments-Response Surface Modeling to optimize the transfection process, the function of propyl-PEI was compared to that of unmodified PEI in both parental CHO-S cells and a subclone (Clone 4), which exhibited superior transgene expression via an increased resistance to polyplex cytotoxicity. The combination of propyl-PEI and Clone 4 doubled the efficiency of recombinant DNA utilization and reporter protein production. These data show that for maximal efficacy, strategies to increase polyplex internalization into cells must be used in concert with strategies to offset the inherent cytotoxicity of this process. © 2014 American Institute of Chemical Engineers.

Functionalized coatings by cold spray: An in vitro study of micro- and nanocrystalline hydroxyapatite compared to porous titanium.

PubMed

Vilardell, A M; Cinca, N; Garcia-Giralt, N; Dosta, S; Cano, I G; Nogués, X; Guilemany, J M

2018-06-01

Three different surface treatments on a Ti6Al4V alloy have been in vitro tested for possible application in cementless joint prosthesis. All of them involve the novelty of using the Cold Spray technology for their deposition: (i) an as-sprayed highly rough titanium and, followed by the deposition of a thin hydroxyapatite layer with (ii) microcrystalline or (iii) nanocrystalline structure. Primary human osteoblasts were extracted from knee and seeded onto the three different surfaces. Cell viability was tested by MTS and LIVE/DEAD assays, cell differentiation by alkaline phosphatase (ALP) quantification and cell morphology by Phalloidin staining. All tests were carried out at 1, 7 and 14 days of cell culture. Different cell morphologies between titanium and hydroxyapatite surfaces were exhibited. At 1 day of cell culture, cells on the titanium coating were spread and flattened, expanding the filopodia actin filaments in all directions, while cells on the hydroxyapatite coatings showed round like-shape morphology due to slower attachment. Higher cell viability was detected at all times of cell culture on titanium coating due to a better attachment at 1 day. However, from 7 days of cell culture, cells on hydroxyapatite showed good attachment onto surfaces and highly increased their proliferation, mostly on nanocrystalline, achieving similar cell viability levels than titanium coatings. ALP levels were significantly higher in titanium, in part, because of greatest cell number. Overall, the best cell functional results were obtained on titanium coatings whereas microcrystalline hydroxyapatite presented the worst cellular parameters. However, results indicate that nanocrystalline hydroxyapatite coatings may achieve promising results for the faster cell proliferation once cells are attached on the surface. Copyright © 2018 Elsevier B.V. All rights reserved.

Global phenotypic characterisation of human platelet lysate expanded MSCs by high-throughput flow cytometry.

PubMed

Reis, Monica; McDonald, David; Nicholson, Lindsay; Godthardt, Kathrin; Knobel, Sebastian; Dickinson, Anne M; Filby, Andrew; Wang, Xiao-Nong

2018-03-02

Mesenchymal stromal cells (MSCs) are a promising cell source to develop cell therapy for many diseases. Human platelet lysate (PLT) is increasingly used as an alternative to foetal calf serum (FCS) for clinical-scale MSC production. To date, the global surface protein expression of PLT-expended MSCs (MSC-PLT) is not known. To investigate this, paired MSC-PLT and MSC-FCS were analysed in parallel using high-throughput flow cytometry for the expression of 356 cell surface proteins. MSC-PLT showed differential surface protein expression compared to their MSC-FCS counterpart. Higher percentage of positive cells was observed in MSC-PLT for 48 surface proteins, of which 13 were significantly enriched on MSC-PLT. This finding was validated using multiparameter flow cytometry and further confirmed by quantitative staining intensity analysis. The enriched surface proteins are relevant to increased proliferation and migration capacity, as well as enhanced chondrogenic and osteogenic differentiation properties. In silico network analysis revealed that these enriched surface proteins are involved in three distinct networks that are associated with inflammatory responses, carbohydrate metabolism and cellular motility. This is the first study reporting differential cell surface protein expression between MSC-PLT and MSC-FSC. Further studies are required to uncover the impact of those enriched proteins on biological functions of MSC-PLT.

ABI domain containing proteins contribute to surface protein display and cell division in Staphylococcus aureus

PubMed Central

Frankel, Matthew B.; Wojcik, Brandon; DeDent, Andrea C.; Missiakas, Dominique M.; Schneewind, Olaf

2012-01-01

Summary The human pathogen Staphyloccocus aureus requires cell wall anchored surface proteins to cause disease. During cell division, surface proteins with YSIRK signal peptides are secreted into the cross wall, a layer of newly synthesized peptidoglycan between separating daughter cells. The molecular determinants for the trafficking of surface proteins are, however, still unknown. We screened mutants with non-redundant transposon insertions by fluorescence-activated cell sorting for reduced deposition of protein A (SpA) into the staphylococcal envelope. Three mutants, each of which harbored transposon insertions in genes for transmembrane proteins, displayed greatly reduced envelope abundance of SpA and surface proteins with YSIRK signal peptides. Characterization of the corresponding mutations identified three transmembrane proteins with abortive infectivity (ABI) domains, elements first described in lactococci for their role in phage exclusion. Mutations in genes for ABI domain proteins, designated spdA, spdB and spdC (surface protein display), diminish the expression of surface proteins with YSIRK signal peptides, but not of precursor proteins with conventional signal peptides. spdA, spdB and spdC mutants display an increase in the thickness of cross walls and in the relative abundance of staphylococci with cross walls, suggesting that spd mutations may represent a possible link between staphylococcal cell division and protein secretion. PMID:20923422

Swimming Motility Reduces Deposition to Silica Surfaces

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

Lu, Nanxi; Massoudieh, Arash; Liang, Xiaomeng

The role of swimming motility on bacterial transport and fate in porous media was evaluated. We present microscopic evidence showing that strong swimming motility reduces attachment of Azotobacter vinelandii cells to silica surfaces. Applying global and cluster statistical analyses to microscopic videos taken under non-flow conditions, wild type, flagellated A. vinelandii strain DJ showed strong swimming ability with an average speed of 13.1 μm/s, DJ77 showed impaired swimming averaged at 8.7 μm/s, and both the non-flagellated JZ52 and chemically treated DJ cells were non-motile. Quantitative analyses of trajectories observed at different distances above the collector of a radial stagnation pointmore » flow cell (RSPF) revealed that both swimming and non-swimming cells moved with the flow when at a distance of at least 20 μm from the collector surface. Near the surface, DJ cells showed both horizontal and vertical movement diverging them from reaching surfaces, while chemically treated DJ cells moved with the flow to reach surfaces, suggesting that strong swimming reduced attachment. In agreement with the RSPF results, the deposition rates obtained for two-dimensional multiple-collector micromodels were also lowest for DJ, while DJ77 and JZ52 showed similar values. Strong swimming specifically reduced deposition on the upstream surfaces of the micromodel collectors.« less

Dramatically reduced surface expression of NK cell receptor KIR2DS3 is attributed to multiple residues throughout the molecule.

PubMed

VandenBussche, C J; Mulrooney, T J; Frazier, W R; Dakshanamurthy, S; Hurley, C K

2009-03-01

Using flow cytometry, fluorescent microscopy and examination of receptor glycosylation status, we demonstrate that an entire killer cell immunoglobulin-like receptor (KIR) locus (KIR2DS3)--assumed earlier to be surface expressed--appears to have little appreciable surface expression in transfected cells. This phenotype was noted for receptors encoded by three allelic variants including the common KIR2DS3*001 allele. Comparing the surface expression of KIR2DS3 with that of the better-studied KIR2DS1 molecule in two different cell lines, mutational analysis identified multiple polymorphic amino-acid residues that significantly alter the proportion of molecules present on the cell surface. A simultaneous substitution of five residues localized to the leader peptide (residues -18 and -7), second domain (residues 123 and 150) and transmembrane region (residue 234) was required to restore KIR2DS3 to the expression level of KIR2DS1. Corresponding simultaneous substitutions of KIR2DS1 to the KIR2DS3 residues resulted in a dramatically decreased surface expression. Molecular modeling was used to predict how these substitutions contribute to this phenotype. Alterations in receptor surface expression are likely to affect the balance of immune cell signaling impacting the characteristics of the response to pathogens or malignancy.

ABI domain-containing proteins contribute to surface protein display and cell division in Staphylococcus aureus.

PubMed

Frankel, Matthew B; Wojcik, Brandon M; DeDent, Andrea C; Missiakas, Dominique M; Schneewind, Olaf

2010-10-01

The human pathogen Staphylococcus aureus requires cell wall anchored surface proteins to cause disease. During cell division, surface proteins with YSIRK signal peptides are secreted into the cross-wall, a layer of newly synthesized peptidoglycan between separating daughter cells. The molecular determinants for the trafficking of surface proteins are, however, still unknown. We screened mutants with non-redundant transposon insertions by fluorescence-activated cell sorting for reduced deposition of protein A (SpA) into the staphylococcal envelope. Three mutants, each of which harboured transposon insertions in genes for transmembrane proteins, displayed greatly reduced envelope abundance of SpA and surface proteins with YSIRK signal peptides. Characterization of the corresponding mutations identified three transmembrane proteins with abortive infectivity (ABI) domains, elements first described in lactococci for their role in phage exclusion. Mutations in genes for ABI domain proteins, designated spdA, spdB and spdC (surface protein display), diminish the expression of surface proteins with YSIRK signal peptides, but not of precursor proteins with conventional signal peptides. spdA, spdB and spdC mutants display an increase in the thickness of cross-walls and in the relative abundance of staphylococci with cross-walls, suggesting that spd mutations may represent a possible link between staphylococcal cell division and protein secretion. © 2010 Blackwell Publishing Ltd.

The influence of nanotexturing of poly(lactic-co-glycolic acid) films upon human ovarian cancer cell attachment

NASA Astrophysics Data System (ADS)

Yaşayan, Gökçen; Xue, Xuan; Collier, Pamela; Clarke, Philip; Alexander, Morgan R.; Marlow, Maria

2016-06-01

In this study, we have produced nanotextured poly(lactic-co-glycolic acid) (PLGA) films by using polystyrene (PS) particles as a template to make a polydimethylsiloxane mould against which PLGA is solvent cast. Biocompatible, biodegradable and nanotextured PLGA films were prepared with PS particles of diameter of 57, 99, 210, and 280 nm that produced domes of the same dimension in the PLGA surface. The effect of the particulate monolayer templating method was investigated to enable preparation of the films with uniformly ordered surface nanodomes. Cell attachment of a human ovarian cancer cell line (OVCAR3) alone and co-cultured with mesenchymal stem cells (MSCs) was evaluated on flat and topographically nano-patterned surfaces. Cell numbers were observed to increase on the nanotextured surfaces compared to non-textured surfaces both with OVCAR3 cultures and OVCAR3-MSC co-cultures at 24 and 48 h time points.

Current conducting end plate of fuel cell assembly

DOEpatents

Walsh, Michael M.

1999-01-01

A fuel cell assembly has a current conducting end plate with a conductive body formed integrally with isolating material. The conductive body has a first surface, a second surface opposite the first surface, and an electrical connector. The first surface has an exposed portion for conducting current between a working section of the fuel cell assembly and the electrical connector. The isolating material is positioned on at least a portion of the second surface. The conductive body can have support passage(s) extending therethrough for receiving structural member(s) of the fuel cell assembly. Isolating material can electrically isolate the conductive body from the structural member(s). The conductive body can have service passage(s) extending therethrough for servicing one or more fluids for the fuel cell assembly. Isolating material can chemically isolate the one or more fluids from the conductive body. The isolating material can also electrically isolate the conductive body from the one or more fluids.

Cell surface differences of Naegleria fowleri and Naegleria lovaniensis exposed with surface markers.

PubMed

González-Robles, Arturo; Castañón, Guadalupe; Cristóbal-Ramos, Ana Ruth; Hernández-Ramírez, Verónica Ivonne; Omaña-Molina, Maritza; Martínez-Palomo, Adolfo

2007-12-01

Differences in the distribution of diverse cell surface coat markers were found between Naegleria fowleri and Naegleria lovaniensis. The presence of carbohydrate-containing components in the cell coat of the two species was detected by selective staining with ruthenium red and alcian blue. Using both markers, N. fowleri presented a thicker deposit than N. lovaniensis. The existence of exposed mannose or glucose residues was revealed by discriminatory agglutination with the plant lectin Concanavalin A. These sugar residues were also visualized at the cell surface of these parasites either by transmission electron microscopy or by fluorescein-tagged Concanavalin A. Using this lectin cap formation was induced only in N. fowleri. The anionic sites on the cell surface detected by means of cationized ferritin were more apparent in N. fowleri. Biotinylation assays confirmed that even though the two amoebae species have some analogous plasma membrane proteins, there is a clear difference in their composition.

Passivating Window/First Layer AR Coating for Space Solar Cells

NASA Technical Reports Server (NTRS)

Faur, Mircea; Faur, Maria; Bailey, S. G.; Flood, D. J.; Brinker, D. J.; Alterovitz, S. A.; Wheeler, D. R.; Matesscu, G.; Goradia, C.; Goradia, M.

2004-01-01

Chemically grown oxides, if well designed, offer excellent surface passivation of the emitter surface of space solar cells and can be used as effective passivating window/first layer AR coating. In this paper, we demonstrate the effectiveness of using a simple room temperature wet chemical technique to grow cost effective passivating layers on solar cell front surfaces after the front grid metallization step. These passivating layers can be grown both on planar and porous surfaces. Our results show that these oxide layers: (i) can effectively passivate the from the surface, (ii) can serve as an effective optical window/first layer AR coating, (iii) are chemically, thermally and UV stable, and (iv) have the potential of improving the BOL and especially the EOL efficiency of space solar cells. The potential of using this concept to simplify the III-V based space cell heterostructures while increasing their BOL and EOL efficiency is also discussed.

Isolation of mouse pancreatic alpha, beta, duct and acinar populations with cell surface markers.

PubMed

Dorrell, Craig; Grompe, Maria T; Pan, Fong Cheng; Zhong, Yongping; Canaday, Pamela S; Shultz, Leonard D; Greiner, Dale L; Wright, Chris V; Streeter, Philip R; Grompe, Markus

2011-06-06

Tools permitting the isolation of live pancreatic cell subsets for culture and/or molecular analysis are limited. To address this, we developed a collection of monoclonal antibodies with selective surface labeling of endocrine and exocrine pancreatic cell types. Cell type labeling specificity and cell surface reactivity were validated on mouse pancreatic sections and by gene expression analysis of cells isolated using FACS. Five antibodies which marked populations of particular interest were used to isolate and study viable populations of purified pancreatic ducts, acinar cells, and subsets of acinar cells from whole pancreatic tissue or of alpha or beta cells from isolated mouse islets. Gene expression analysis showed the presence of known endocrine markers in alpha and beta cell populations and revealed that TTR and DPPIV are primarily expressed in alpha cells whereas DGKB and GPM6A have a beta cell specific expression profile. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Pure and Oxidized Copper Materials as Potential Antimicrobial Surfaces for Spaceflight Activities.

PubMed

Hahn, C; Hans, M; Hein, C; Mancinelli, R L; Mücklich, F; Wirth, R; Rettberg, P; Hellweg, C E; Moeller, R

2017-12-01

Microbial biofilms can lead to persistent infections and degrade a variety of materials, and they are notorious for their persistence and resistance to eradication. During long-duration space missions, microbial biofilms present a danger to crew health and spacecraft integrity. The use of antimicrobial surfaces provides an alternative strategy for inhibiting microbial growth and biofilm formation to conventional cleaning procedures and the use of disinfectants. Antimicrobial surfaces contain organic or inorganic compounds, such as antimicrobial peptides or copper and silver, that inhibit microbial growth. The efficacy of wetted oxidized copper layers and pure copper surfaces as antimicrobial agents was tested by applying cultures of Escherichia coli and Staphylococcus cohnii to these metallic surfaces. Stainless steel surfaces were used as non-inhibitory control surfaces. The production of reactive oxygen species and membrane damage increased rapidly within 1 h of exposure on pure copper surfaces, but the effect on cell survival was negligible even after 2 h of exposure. However, longer exposure times of up to 4 h led to a rapid decrease in cell survival, whereby the survival of cells was additionally dependent on the exposed cell density. Finally, the release of metal ions was determined to identify a possible correlation between copper ions in suspension and cell survival. These measurements indicated a steady increase of free copper ions, which were released indirectly by cells presumably through excreted complexing agents. These data indicate that the application of antimicrobial surfaces in spaceflight facilities could improve crew health and mitigate material damage caused by microbial contamination and biofilm formation. Furthermore, the results of this study indicate that cuprous oxide layers were superior to pure copper surfaces related to the antimicrobial effect and that cell density is a significant factor that influences the time dependence of antimicrobial activity. Key Words: Contact killing-E. coli-S. cohnii-Antimicrobial copper surfaces-Copper oxide layers-Human health-Planetary protection. Astrobiology 17, 1183-1191.

Apparatus and method for the electrolytic production of metals

DOEpatents

Sadoway, Donald R.

1991-01-01

Improved electrolytic cells and methods for producing metals by electrolytic reduction of a compound dissolved in a molten electrolyte are disclosed. In the improved cells and methods, a protective surface layer is formed upon at least one electrode in the electrolytic reduction cell and, optionally, upon the lining of the cell. This protective surface layer comprises a material that, at the operating conditions of the cell: (a) is not substantially reduced by the metal product; (b) is not substantially reactive with the cell electrolyte to form materials that are reactive with the metal product; and, (c) has an electrochemical potential that is more electronegative than that of the compound undergoing electrolysis to produce the metal product of the cell. The protective surface layer can be formed upon an electrode metal layer comprising a material, the oxide of which also satisfies the protective layer selection criteria. The protective layer material can also be used on the surface of a cell lining.

Method of making a back contacted solar cell

DOEpatents

Gee, J.M.

1995-11-21

A back-contacted solar cell is described having laser-drilled vias connecting the front-surface carrier-collector junction to an electrode grid on the back surface. The structure may also include a rear surface carrier-collector junction connected to the same grid. The substrate is connected to a second grid which is interdigitated with the first. Both grids are configured for easy series connection with neighboring cells. Several processes are disclosed to produce the cell. 2 figs.

Surface Curvature Differentially Regulates Stem Cell Migration and Differentiation via Altered Attachment Morphology and Nuclear Deformation

PubMed Central

Werner, Maike; Blanquer, Sébastien B. G.; Haimi, Suvi P.; Korus, Gabriela; Dunlop, John W. C.; Duda, Georg N.; Grijpma, Dirk. W.

2016-01-01

Signals from the microenvironment around a cell are known to influence cell behavior. Material properties, such as biochemical composition and substrate stiffness, are today accepted as significant regulators of stem cell fate. The knowledge of how cell behavior is influenced by 3D geometric cues is, however, strongly limited despite its potential relevance for the understanding of tissue regenerative processes and the design of biomaterials. Here, the role of surface curvature on the migratory and differentiation behavior of human mesenchymal stem cells (hMSCs) has been investigated on 3D surfaces with well‐defined geometric features produced by stereolithography. Time lapse microscopy reveals a significant increase of cell migration speed on concave spherical compared to convex spherical structures and flat surfaces resulting from an upward‐lift of the cell body due to cytoskeletal forces. On convex surfaces, cytoskeletal forces lead to substantial nuclear deformation, increase lamin‐A levels and promote osteogenic differentiation. The findings of this study demonstrate a so far missing link between 3D surface curvature and hMSC behavior. This will not only help to better understand the role of extracellular matrix architecture in health and disease but also give new insights in how 3D geometries can be used as a cell‐instructive material parameter in the field of biomaterial‐guided tissue regeneration. PMID:28251054

Immobilization of heparin/poly-(L)-lysine nanoparticles on dopamine-coated surface to create a heparin density gradient for selective direction of platelet and vascular cells behavior.

PubMed

Liu, Tao; Liu, Yang; Chen, Yuan; Liu, Shihui; Maitz, Manfred F; Wang, Xue; Zhang, Kun; Wang, Jian; Wang, Yuan; Chen, Junying; Huang, Nan

2014-05-01

Restenosis, thrombosis formation and delayed endothelium regeneration continue to be problematic for coronary artery stent therapy. To improve the hemocompatibility of the cardiovascular implants and selectively direct vascular cell behavior, a novel kind of heparin/poly-l-lysine (Hep/PLL) nanoparticle was developed and immobilized on a dopamine-coated surface. The stability and structural characteristics of the nanoparticles changed with the Hep:PLL concentration ratio. A Hep density gradient was created on a surface by immobilizing nanoparticles with various Hep:PLL ratios on a dopamine-coated surface. Antithrombin III binding quantity was significantly enhanced, and in plasma the APTT and TT times as coagulation tests were prolonged, depending on the Hep density. A low Hep density is sufficient to prevent platelet adhesion and activation. The sensitivity of vascular cells to the Hep density is very different: high Hep density inhibits the growth of all vascular cells, while low Hep density could selectively inhibit smooth muscle cell hyperplasia but promote endothelial progenitor cells and endothelial cell proliferation. These observations provide important guidance for modification of surface heparinization. We suggest that this method will provide a potential means to construct a suitable platform on a stent surface for selective direction of vascular cell behavior with low side effects. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Enhanced methanol utilization in direct methanol fuel cell

DOEpatents

Ren, Xiaoming; Gottesfeld, Shimshon

2001-10-02

The fuel utilization of a direct methanol fuel cell is enhanced for improved cell efficiency. Distribution plates at the anode and cathode of the fuel cell are configured to distribute reactants vertically and laterally uniformly over a catalyzed membrane surface of the fuel cell. A conductive sheet between the anode distribution plate and the anodic membrane surface forms a mass transport barrier to the methanol fuel that is large relative to a mass transport barrier for a gaseous hydrogen fuel cell. In a preferred embodiment, the distribution plate is a perforated corrugated sheet. The mass transport barrier may be conveniently increased by increasing the thickness of an anode conductive sheet adjacent the membrane surface of the fuel cell.

SiN{sub x} layers on nanostructured Si solar cells: Effective for optical absorption and carrier collection

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

Cho, Yunae; Kim, Eunah; Gwon, Minji

2015-10-12

We compared nanopatterned Si solar cells with and without SiN{sub x} layers. The SiN{sub x} layer coating significantly improved the internal quantum efficiency of the nanopatterned cells at long wavelengths as well as short wavelengths, whereas the surface passivation helped carrier collection of flat cells mainly at short wavelengths. The surface nanostructured array enhanced the optical absorption and also concentrated incoming light near the surface in broad wavelength range. Resulting high density of the photo-excited carriers near the surface could lead to significant recombination loss and the SiN{sub x} layer played a crucial role in the improved carrier collection ofmore » the nanostructured solar cells.« less

Correlation between surface carbon concentration and adhesive strength at the Si cell/EVA interface in a PV module

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

Dhere, N.G.; Wollam, M.E.; Gadre, K.S.

1997-12-31

Silicon solar cell/EVA composite is being studied with an objective to further improve the manufacturing technology of PV modules. Sample extraction and adhesion strength measurement process has been modified. Silicon and EVA samples were extracted from solar cells of new and field-deployed modules. Optical microscopy, SEM, and AES of samples from new modules revealed EVA islands covering most of the silicon cell surface indicating a cohesive failure. A good correlation was observed between the adhesive strength and surface concentration of carbon. A low carbon concentration which indicated less EVA clinging to cell surface always resulted in low adhesive strengths. Themore » correlation provides a simple technique for inferring properties of EVA.« less

The effect of MTAD, an endodontic irrigant, on fibroblast attachment to periodontally affected root surfaces: A SEM analysis

PubMed Central

Ghandi, Mostafa; Houshmand, Behzad; Nekoofar, Mohammad H.; Tabor, Rachel K.; Yadeghari, Zahra; Dummer, Paul M. H.

2013-01-01

Background: Root surface debridement (RSD) is necessary to create an environment suitable for reattachment of the periodontium. Root surface conditioning may aid the formation of a biocompatible surface suitable for cell reattachment. BioPure™ MTAD (mixture of Doxycycline, citric acid and a detergent) is an endodontic irrigant with antibacterial properties and the ability to remove smear layer. It was hypothesized that MTAD may be useful for root surface conditioning. The efficacy of MTAD as a conditioner was measured by examining fibroblast attachment to root surfaces. Materials and Methods: Thirty-two specimens of human teeth with advanced periodontal disease were used. The surfaces were root planed until smooth. Half of the specimens were treated with 0.9% saline and the other samples with Biopure MTAD. As a negative control group, five further samples were left unscaled with surface calculus. Human gingival fibroblast cells HGF1-PI1 were cultured and poured over the tooth specimens and incubated. After fixation, the samples were sputter-coated with gold and examined with a SEM. The morphology and number of attached, fixed viable cells were examined. The data was analysed using the Mann-Whitney-U statistical test. Results: There was no significant difference between the numbers of attached cells in the experimental group treated with MTAD and the control group treated with saline. Little or no attached cells were seen in the negative control group. Conclusion: RSD created an environment suitable for cell growth and attachment in a laboratory setting. The use of MTAD did not promote the attachment and growth of cells on the surface of human roots following RSD. PMID:23869124

Visible light controls cell adhesion on a photoswitchable biointerface.

PubMed

Ming, Zunzhen; Hua, Xin; Xue, Yuan; Lin, Qiuning; Bao, Chunyan; Zhu, Linyong

2018-05-04

Bioactive surfaces with specific interactions with cells have been greatly interested due to their potential applications in biosensors and tissue engineering. Herein, we fabricated a dopamine contained photoswitch molecule (compound 1) which could form self-assembled monolayer (SAM) on substrates. The SAM showed a good photoswitch ability and manifested excellent fatigue resistance, which displayed its potential application as a biologically friendly surface coating. Contact angle analysis and cell experiments exhibited that the SAM surface was hydrophobic before irradiation which favored cell adhesion, while, it turned hydrophilic and induced cell unfouling or detachment after light irradiation. The uses of visible light stimulation (λ ex  = 530 nm) and the reversible regulation on cell adhesion and detachment should open up new avenues for bioacitve surfaces in biomedical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Antibiotic Algae by Chemical Surface Engineering.

PubMed

Kerschgens, Isabel P; Gademann, Karl

2018-03-02

Chemical cell-surface engineering is a tool for modifying and altering cellular functions. Herein, we report the introduction of an antibiotic phenotype to the green alga Chlamydomonas reinhardtii by chemically modifying its cell surface. Flow cytometry and confocal microscopy studies demonstrated that a hybrid of the antibiotic vancomycin and a 4-hydroxyproline oligomer binds reversibly to the cell wall without affecting the viability or motility of the cells. The modified cells were used to inhibit bacterial growth of Gram-positive Bacillus subtilis cultures. Delivery of the antibiotic from the microalgae to the bacterial cells was verified by microscopy. Our studies provide compelling evidence that 1) chemical surface engineering constitutes a useful tool for the introduction of new, previously unknown functionality, and 2) living microalgae can serve as new platforms for drug delivery. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Goblet Cells of the Conjunctiva: A Review of Recent Findings

PubMed Central

Gipson, Ilene K

2016-01-01

Goblet cells within the conjunctival epithelium are specialized cells that secrete mucins onto the surface of the eye. Recent research has demonstrated new characteristics of the cells, including factors influencing their differentiation, their gene products and their functions at the ocular surface. The following review summarizes the newly discovered aspects of the role of Spdef, a member of the Ets transcription factor family in conjunctival goblet cell differentiation, the newly discovered goblet cell products including claudin2, the Wnt inhibitor Frzb, and the transmembrane mucin Muc16. The current concepts of conjunctival goblet cell function, including debris removal and immune surveillance are reviewed, as are changes in the goblet cell population in ocular surface diseases. Major remaining questions regarding conjunctival cell biology are discussed. PMID:27091323

Maintaining the pluripotency of mouse embryonic stem cells on gold nanoparticle layers with nanoscale but not microscale surface roughness.

PubMed

Lyu, Zhonglin; Wang, Hongwei; Wang, Yanyun; Ding, Kaiguo; Liu, Huan; Yuan, Lin; Shi, Xiujuan; Wang, Mengmeng; Wang, Yanwei; Chen, Hong

2014-06-21

Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction.

Surface multiheme c-type cytochromes from Thermincola potens: Implications for dissimilatory metal reduction by Gram-positive bacteria

NASA Astrophysics Data System (ADS)

Carlson, H. K.; Iavarone, A. T.; Gorur, A.; Yeo, B. S.; Tran, R.; Melnyk, R. A.; Mathies, R. A.; Auer, M.; Coates, J. D.

2011-12-01

Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they have been shown to be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or the humic substances analog, anthraquinone-2,6-disulfonate (AQDS). The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS and that several MHCs are localized to the cell wall or cell surface of T. potens. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results are the first direct evidence for cell-wall associated cytochromes and MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.

Cell penetrating peptide-modified poly(lactic-co-glycolic acid) nanoparticles with enhanced cell internalization.

PubMed

Steinbach, Jill M; Seo, Young-Eun; Saltzman, W Mark

2016-01-01

The surface modification of nanoparticles (NPs) can enhance the intracellular delivery of drugs, proteins, and genetic agents. Here we studied the effect of different surface ligands, including cell penetrating peptides (CPPs), on the cell binding and internalization of poly(lactic-co-glycolic) (PLGA) NPs. Relative to unmodified NPs, we observed that surface-modified NPs greatly enhanced cell internalization. Using one CPP, MPG (unabbreviated notation), that achieved the highest degree of internalization at both low and high surface modification densities, we evaluated the effect of two different NP surface chemistries on cell internalization. After 2h, avidin-MPG NPs enhanced cellular internalization by 5 to 26-fold relative to DSPE-MPG NP formulations. Yet, despite a 5-fold increase in MPG density on DSPE compared to Avidin NPs, both formulations resulted in similar internalization levels (48 and 64-fold, respectively) after 24h. Regardless of surface modification, all NPs were internalized through an energy-dependent, clathrin-mediated process, and became dispersed throughout the cell. Overall both Avidin- and DSPE-CPP modified NPs significantly increased internalization and offer promising delivery options for applications in which internalization presents challenges to efficacious delivery. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.