Endothelial cell adhesion on polyurethanes containing covalently attached RGD-peptides.

Peptides based on cell-adhesive regions of fibronectin, Arg-Gly-Asp-Ser (RGDS), and vitronectin, Arg-Gly-Asp-Val (RGDV), were covalently bound to a polyurethane backbone via amide bonds. Nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopies were used to monitor the reactions. The amount of grafted peptide was determined by amino acid analysis. X-ray photoelectron spectroscopy (XPS) suggested the presence of the grafted peptide at the polymer-air interface in vacuo. Dynamic contact angle analysis showed that, in water, the peptide-grafted polyurethane surfaces were more polar than the underivatized polyurethane indicating enrichment of peptide groups at the surface. The attachment and spreading of human umbilical vein endothelial cells (HUVECs) on the underivatized and peptide-grafted polyurethanes was investigated. The GRGDSY- and GRGDVY-grafted substrates supported cell adhesion and spreading even without serum in the culture medium. The GRGDVY-grafted substrate supported a larger number of adherent cells and a higher extent of cell spreading than the GRGDSY-grafted substrate. These RGD-containing peptide-grafted polyurethane copolymers may be useful in providing an easily prepared cell-adhesive substrate for various biomaterial applications.     

In vitro assessment of bioactive coatings for neural implant applications

Recent efforts in our laboratory have focused on developing methods for immobilizing bioactive peptides to low cell-adhesive dextran monolayer coatings and promoting biospecific cell adhesion for biomaterial implant applications. In the current study, this dextran-based bioactive coating technology was developed for silicon, polyimide, and gold, the base materials utilized to fabricate our prototype neural implants. Chemical composition of all modified surfaces was verified by X-ray photoelectron spectroscopy (XPS). We observed that surface-immobilized dextran supported very little cell adhesion in vitro (24-h incubation with serum-supplemented medium) on all base materials. Inactive nonadhesion-promoting Gly-Arg-Ala-Asp-Ser-Pro peptides immobilized on dextran-coated materials promoted adhesion and spreading at low levels not significantly different from dextran-coated substrates. Arg-Gly-Asp (RGD) peptide-grafted surfaces were observed to promote substantial fibroblast and glial cell adhesion with minimal PC12 (neuronal cell) adhesion. In contrast, dextran-coated materials with surface-grafted laminin-based, neurite-promoting Ile-Lys-Val-Ala-Val (IKVAV) peptide promoted substantial neuron cell adhesion and minimal fibroblast and glial cell adhesion. It was concluded that neuron-selective substrates are feasible using dextran-based surface chemistry strategies. The chemical surface modifications could be utilized to establish a stable neural tissue-implant interface for long-term performance of neural prosthetic devices.     

Glycophase glass revisited: protein adsorption and cell growth on glass surfaces bearing immobilized glycerol monosaccharides

Gamma-Glycerylpropylsilyl or "glycophase" glass has been promoted as a non-fouling surface, resistant to protein adsorption and cell attachment, on which one can immobilize oligopeptide ligands, and thus create cell-type-specific culture surfaces. The present study confirmed that the glycerol-rich glycophase surface is a useful support for peptide immobilization. But glycophase glass was observed to adsorb more albumin than glass. At pH 7.4, desorption studies revealed that albumin bound more tightly to glycophase glass than to glass. Moreover, the growth rates, morphologies, and functions of transgenic betaG I/17 insulinoma cell cultures were equivalent on the two surfaces. Glycophase glass is neither protein- nor cell-repellant.     

Development of RGD peptides grafted onto silica surfaces: XPS characterization and human endothelial cell interactions.

The attachment of human umbilical vein endothelial cells (HUVECs) on substrates that had been covalently grafted with the cell adhesion peptides Arg-Gly-Asp (RGD) was investigated. This approach was used to provide substrates that are adhesive to cells even in the absence of serum proteins and to cells that have had no prior treatment of the surface with proteins that promote cell adhesion. We wanted to improve control of cellular interactions with cell-adhesive materials by providing fixedly bound adhesion ligands. Silica was examined as a model surface. The peptides were grafted using three different steps: grafting of aminosilane molecules; reaction with a maleimide molecule; and immobilization of cell-binding peptides containing the RGD sequence. The RGD-grafted surface was characterized by X-ray photoelectron spectroscopy (XPS) and contact-angle measurements.     

Effects of plasma treated PET and PTFE on expression of adhesion molecules by human endothelial cells in vitro

The aim of this study was to evaluate the expression of adhesion molecules on the surface of human endothelial cells in response to the systematic variation in materials properties by the ammonia plasma modification of polyethylene terephthalate (PET) and polytetrafluorethylene (PTFE). These adhesion molecules act as mediators of cell adhesion, play a role in the modulation of cell adhesion on biomaterials and therefore condition the response of tissues to implants. First and second passage human umbilical vein endothelial cells (HUVECs) were cultured on plasma treated and untreated PET and PTFE. HUVECs grown on polystyrene tissue culture coverslips and HUVECs stimulated with tumour necrosis factor (TNF-alpha) were used as controls. After 1 day and 7 days, the expression of adhesion molecules platelet endothelial cell adhesion molecule-1 (PECAM-1), intercellular adhesion molecule-1 (ICAM-1), Integrin alphavbeta3, vascular cell adhesion molecule-1 (VCAM-1), E-selectin, P-selectin and L-selectin were evaluated using flow cytometry and immunohistochemistry. There was a slight increase in positive cell numbers expressing the adhesion molecules ICAM-1 and VCAM-1 on plasma treated PET and PTFE. A significant increase in E-selectin positive cells on untreated PTFE was demonstrated after 7 days. Stimulation with TNF-alpha demonstrated a significant increase in the proportion of ICAM-1. VCAM-1 and E-selectin positive cells. Almost all cells expressed PECAM-1 and integrin alphavbeta3, on both materials and controls but did not express P- and L-selectin on any surface. When second passage cells were used, the expression of the adhesion molecules ICAM-1 and VCAM-1 was markedly increased on all surfaces but not with TNF-alpha. These significant differences were not observed in other adhesion molecules. These results were supported by immunohistochemical studies. The effects of plasma treated PET and PTFE on cell adhesion and proliferation was also studied. There was a 1.3-fold increase in cell numbers adhered on ammonia plasma treated PET compared to untreated PET and a 5.5-fold increase in cell numbers on treated PTFE compared to untreated PTFE after 1 day. This is significantly different when analysed statistically. After 7 days, cell number increased significantly on all surfaces compared to 1 day, except for untreated PTFE which conversely reduced by 41%. Cell number on the surface of untreated PET was no different to treated PET on days 1 and 7 when second passage cells were used. The study has shown that the plasma treatment of PET and PTFE with ammonia improves the adhesion and growth of endothelial cells and slightly upregulates the expression of adhesion molecules. This surface modification should promote colonisation of an artificial vascular prosthesis by endothelial cells and make it less vulnerable to immune system cells of the recipient. In addition, it should be considered which passage of cells is used due to the different adhesion features of different passages of HUVECs on untreated PET.     

等离子体表面改性涤纶材料的血浆蛋白吸附与血小板黏附行为研究

采用等离子体表面接枝改性技术在涤纶 (聚对苯二甲酸乙二醇酯 ,PET)材料表面接枝不同分子量的聚乙二醇 (PEG) ,从表面能与界面自由能的角度分析了血浆蛋白 (纤维蛋白原和白蛋白 )在材料表面的竞争吸附关系 ,结果表明接枝了 PEG长链分子的 PET材料具有优先吸附白蛋白的性质 ,其中接枝 PEG6 0 0 0的 PET优先吸附倾向最明显。预接触白蛋白和纤维蛋白原的 PET材料表面的血小板黏附实验表明 :吸附白蛋白的表面能够显著抑制血小板的黏附和聚集 ,表现出好的血液相容性 ,而吸附了纤维蛋白原的材料表面具有降低血液相容性的性质。     

Synthesis, analytical characterization, and osteoblast adhesion properties on RGD-grafted polypyrrole coatings on titanium substrates

The covalent attachment of an Arg-Gly-Asp (RGD) containing peptide to polypyrrole(PPy)-coated titanium substrates has been investigated in order to develop a bioactive material of potential use in orthopedic fields. Polypyrrole has been employed as the coating polymer because of its suitability to be electrochemically grown directly onto metallic substrates of different shapes, leading to remarkably adherent films. The synthetic peptide Cys-Gly-(Arg-Gly-Asp)-Ser-Pro-Lys, containing the cell-adhesive region of fibronectin (RGD), has been grafted to the polymer substrate via the cysteine residue using a procedure recently developed in the authors laboratory. The effectiveness of grafting was monitored by X-ray photoelectron spectroscopy (XPS), which assessed the presence of the peptide grafted onto the polymer surface exploiting the cysteine sulfur as target element. Neonatal rat calvarial osteoblasts were attached to RGD-modified PPy-coated Ti substrates at levels significantly greater than on unmodified PPy-coated Ti and glass coverslip substrates.     

Synthesis,analytical characterization,and osteoblast adhesion properties on RGD-grafted polypyrrole coatings on titanium substrates

The covalent attachment of an Arg-Gly-Asp (RGD) containing peptide to polypyrrole(PPy)-coated titanium substrates has been investigated in order to develop a bioactive material of potential use in orthopedic fields. Polypyrrole has been employed as the coating polymer because of its suitability to be electrochemically grown directly onto metallic substrates of different shapes, leading to remarkably adherent films. The synthetic peptide Cys-Gly-(Arg-Gly-Asp)-Ser-Pro-Lys, containing the cell-adhesive region of fibronectin(RGD), has been grafted to the polymer substrate via the cysteine residue using a procedure recently developed in the authors laboratory. The effectiveness of grafting was monitored by X-ray photoelectron spectroscopy (XPS), which assessed the presence of the peptide grafted onto the polymer surface exploiting the cysteine sulfur as target element. Neonatal rat calvarial osteoblasts were attached to RGD-modified PPy-coated Ti substrates at levels significantly greater than on unmodified PPy-coated Ti and glass coverslip substrates.     

Correlation of astroglial cell function on micro-patterned surfaces with specific geometric parameters

Microcontact printing techniques were used to modify silicon substrates with arrays of hexagonal features of N1[3-(trimethoxysilyl) propyl]diethylenetriamine (DETA) surrounded by octadecyltrichlorosilane (OTS), which are hydrophilic, cell-adhesive and hydrophobic, non-adhesive organosilanes, respectively. In the presence of serum proteins, LRM55 cell adhesion and morphology on these modified surfaces were best correlated to the width of the cell-adhesive features. On surfaces modified with small (5 microm in width) cell-adhesive features, LRM55 cells elaborated only thin processes. As feature width was increased, cells on these surfaces exhibited increased cell spreading and elaborated wide processes. On surfaces modified with large (>35 microm in width) features, single cells adhered to and spread upon individual DETA features. In a similar fashion, LRM55 cell adhesion density increased with increasing feature width; this correlation could be represented by a simple, second-order relation, and was independent of all other measures of pattern geometry. The results of this study provide evidence that micro-patterning may be effective in controlling astrocyte interaction with implant materials.     

Surface-immobilized dextran limits cell adhesion and spreading

Dextran has recently been investigated as an alternative to polyethylene glycol (PEG) for low protein-binding, cell-resistant coatings on biomaterial surfaces. Although anti-fouling properties of surface-grafted dextran and PEG are quite similar, the multivalent properties of dextran are advantageous when high-density surface immobilization of biologically active molecules to low protein-binding surface coatings is desired. The preferred methods of dextran immobilization for biomaterial applications should be simple with minimal toxicity. In this report, a method is described for covalent immobilization of dextran to material surfaces which involves low residual toxicity reagents in mild aqueous reaction conditions. 70 kDa MW dextran was immobilized on glass and polyethylene terephthalate (PET) surfaces. 3T3 fibroblast cell adhesion was compared on untreated, aminated, and dextran-coated materials. Dextran coatings effectively limited cell adhesion and spreading on glass and PET surfaces in the presence of serum-borne cell adhesion proteins. With dextran-based surface coatings, it will be possible to develop well-defined surface modifications that promote specific cell interactions and perhaps better performance in long-term biomaterial implants.     

Controlled polymerization chemistry to graft architectures that influence cell-material interactions

Acrylate monomers were photografted from polymer substrates to create cell responsive chemically and biologically active surfaces that manipulate cell response. Three monomers, polyethylene glycol monoacrylate (MW 375 g/mol) (PEG375A), a monomeric extra-cellular matrix protein, and a cell-cleavable fluorescent monomer, were spatially photopatterned from a base substrate. The base substrate consisted of a dithiocarbamate (DTC) functionalized urethane diacrylate/tri(ethylene glycol)diacrylate copolymer and was shown to non-specifically support NIH 3T3 fibroblast cell adhesion. The DTC-containing polymer was further modified by grafting PEG375A to demonstrate selective blocking of cell-material interactions. Next, acrylated collagen type I was patterned onto polymer substrates to further promote specific cell interactions (i.e. by presenting cell-adhesive moieties). Hydrophilic PEG375A grafted patterns were shown to prevent 3T3 fibroblast adhesion to polymer in spatially grafted regions, while biologically active acrylated collagen type I promoted cell-surface interactions. Collagen type I was grafted at varying densities (0-7.5 pmol/grafted square), and the extent of cell adhesion and spreading were evaluated for each of these graft densities using fluorescence microscopy. Finally, methacrylated carboxyfluorescein diacetate (CFDA) was synthesized and photografted onto a cell-adhesive substrate as a cell sensing mechanism. The acetate groups found in the structure of CFDA cleave in the presence of cells. This cell-responsive substrate results in fluorescence indicative of acetate-group cleavage associated with cell interactions that occurs in patterned regions on polymer surfaces. Collectively, the results herein show the utility and application of a spatially and temporally controlled photografting process for designing cell responsive polymer surfaces.     

Surface functionalization of titanium with hyaluronic acid/chitosan polyelectrolyte multilayers and RGD for promoting osteoblast functions and inhibiting bacterial adhesion

Titanium (Ti) and its alloys are used extensively in orthopedic implants due to their excellent biocompatibility and mechanical properties. However, titanium-based implant materials have specific complications associated with their applications, such as the loosening of implant-host interface owing to unsatisfactory cell adhesion and the susceptibility of the implants to bacterial infections. Hence, a surface which displays selective biointeractivity, i.e. enhancing beneficial host cell responses but inhibiting pathogenic microbial adhesion, would be highly desirable. This present study aims to improve biocompatibility and confer long-lasting antibacterial properties on Ti via polyelectrolyte multilayers (PEMs) of hyaluronic acid (HA) and chitosan (CH), coupled with surface-immobilized cell-adhesive arginine-glycine-aspartic acid (RGD) peptide. The HA/CH PEM-functionalized Ti is highly effective as an antibacterial surface but the adhesion of bone cells (osteoblasts) is poorer than on pristine Ti. With additional immobilized RGD moieties, the osteoblast adhesion can be significantly improved. The density of the surface-immobilized RGD peptide has a significant effect on osteoblast proliferation and alkaline phosphatase (ALP) activity, and both functions can be increased by 100-200% over that of pristine Ti substrates while retaining high antibacterial efficacy. Such substrates can be expected to have good potential in orthopedic applications.     

The effect of fluid shear stress upon cell adhesion to fibronectin-treated surfaces

Cell attachment to and spreading upon a surface is mediated by adhesion molecules, such as fibronectin. The role of fibronectin in maintaining cell adhesion was examined by measuring cell attachment following exposure of cells to laminar flow in a parallel-plate flow channel. 3T3 fibroblasts were allowed to adhere to glass slides with or without preadsorbed fibronectin for 2 h before exposure to shear stresses ranging from 5 to 140 dyne/cm2. For cells which adhered to glass surfaces, cell loss was biphasic with a significant loss of cells during the first 2 min of flow, followed by a much slower decline in the number of attached cells with time. Following exposure to shear stresses greater than 5 dyne/cm2, the number of attached cells decreased exponentially as the shear stress increased. The distribution of adhesive stresses among the population of cells was log-normal with a median of 50 dyne/cm2, a mean of 82 dyne/cm2 and a standard deviation of 108 dyne/cm2. After exposure to flow for 2 h, the adhesive stress of the remaining cells decreased to a mean value of 50 dyne/cm2. Cell adhesion after exposure to flow was increased by preadsorbing fibronectin to the glass surface. The initial loss of cells from fibronectin-treated glass following exposure to flow correlated with the degree of cell spreading. Preadsorbed fibronectin resulted in a greater number of bonds between the surface and the cell, which in turn promoted cell spreading and increased the adhesive strength of the cell.     

Integrin-mediated adhesion and proliferation of human MSCs elicited by a hydroxyproline-lacking, collagen-like peptide

In this study, we evaluated the competence of a rationally designed collagen-like peptide (CLP-Cys) sequence - containing the minimal essential Glycine-Glutamic acid-Arginine (GER) triplet but lacking the hydroxyproline residue - for supporting human mesenchymal stem cell (hMSC) adhesion, spreading and proliferation. Cellular responses to the CLP-Cys sequence were analyzed by conjugating the peptide to two different substrates - a hard, planar glass surface and a soft hyaluronic acid (HA) particle-based hydrogel. Integrin-mediated cell spreading and adhesion were observed for hMSCs cultivated on the CLP-Cys functionalized surfaces, whereas on control surfaces lacking the peptide motif, cells either did not adhere or maintained a round morphology. On the glass surface, CLP-Cys-mediated spreading led to the formation of extended and well developed stress fibers composed of F-actin bundles and focal adhesion complexes while on the soft gel surface, less cytoskeletal reorganization organization was observed. The hMSCs proliferated significantly on the surfaces presenting CLP-Cys, compared to the control surfaces lacking CLP-Cys. Competitive binding assay employing soluble CLP-Cys revealed a dose-dependent inhibition of hMSC adhesion to the CLP-Cys-presenting surfaces. Blocking the α(2)β(1) receptor on hMSC also resulted in a reduction of cell adhesion on both types of CLP-Cys surfaces, confirming the affinity of CLP-Cys to α(2)β(1) receptors. These results established the competence of the hydroxyproline-free CLP-Cys for eliciting integrin-mediated cellular responses including adhesion, spreading and proliferation. Thus, CLP-Cys-modified HA hydrogels are attractive candidates as bioactive scaffolds for tissue engineering applications.     

Engineering cell-adhesive gellan gum spongy-like hydrogels for regenerative medicine purposes

The similarity between the extracellular matrix of soft tissue and hydrogels, characterized by high-water-content viscoelastic polymeric networks, has been sustaining the advancement of hydrogels for tissue engineering and regenerative medicine (TERM) purposes. Current research on hydrogels has focused on introducing cell-adhesive peptides to promote cell adhesion and spreading, a critical applicability limitation. Here we report the development of gellan gum (GG) spongy-like hydrogels with ameliorated mechanical performance and flexibility in relation to hydrogels, using a simple and cost-effective method. Most importantly, these materials allow the entrapment of different cell types representing mesenchymal, epidermal and osteoblastic phenotypes that spread within the three-dimensional microstructure. This effect was associated with microstructural rearrangements characterized by pore wall thickening and pore size augmentation, and lower water content than precursor hydrogels. These properties significantly affected protein adsorption once cell adhesion was inhibited in the absence of serum. Spongy-like hydrogels are not adhesive for endothelial cells; however, this issue was surpassed by a pre-incubation with a cell-adhesive protein, as demonstrated for other substrates but not for traditional hydrogels. The proposed cell-compatible GG-based structures avoid time-consuming and expensive strategies that have been used to include cell-adhesive features in traditional hydrogels. This, associated with their off-the-shelf availability in an intermediary dried state, represents unique and highly relevant features for diverse TERM applications.     

生物活性短肽RGD在PET表面接枝方法的研究

在高分子材料表面共价引入人工合成的精氨酰-甘氨酰-天冬氨酸三肽(Arg-Gly-Asp peptides，RGD)，以达到让内皮细胞与之特异结合并更加牢固的目的。实验用紫外辐照法将活性基团羧基(-COOH)接枝到聚对苯二甲酸乙二醇酯(Poly(ethylene terephtalate)，PET)膜的表面，将液相合成的RGD三肽耦合接枝到处理过的材料表面，光电子能谱对以羧基为活性基团的接肽反应结果进行分析，光学、电子显微镜观察内皮细胞生长情况以检测接枝短肽的生物活性。内皮细胞生长实验结果表明，成功接枝的RGD序列对材料内皮细胞种植起到了促进作用。本实验成功运用紫外接枝与化学耦合，将生物活性短肽RGD接枝到膜表面，探索了一种新的接枝生物活性短肽的方法。     

Val-ala-pro-gly, an elastin-derived non-integrin ligand: smooth muscle cell adhesion and specificity

The elastin-derived peptide val-ala-pro-gly (VAPG) may be useful as a biospecific cell adhesion ligand for smooth muscle cells. By grafting the peptide sequence into a hydrogel material, we were able to assess its effects on smooth muscle cell adhesion and spreading. These materials are photopolymerizable hydrogels based on acrylate-terminated derivatives of polyethylene glycol (PEG). Because of their high PEG content, these materials are highly resistant to protein adsorption and cell adhesion. However, PEG diacrylate derivatives can be mixed with adhesive peptide-modified PEG monoacrylate derivatives to facilitate cell adhesion. Following photopolymerization, PEG monoacrylate derivatives are grafted into the hydrogel network formed by the PEG diacrylate. This results in covalent immobilization of adhesive peptides to the hydrogel via a flexible linker chain. The resistance of PEG to protein adsorption makes it an ideal material for this model system since cell-material interactions are limited to biomolecules that are covalently incorporated into the material. In this case we were able to demonstrate that VAPG is specific for adhesion of smooth muscle cells. It also was shown that fibroblasts, endothelial cells, and platelets cannot adhere to VAPG. In addition, not only was smooth muscle cell adhesion dependent on ligand concentration, but also cell spreading increased with increasing ligand concentration.     

Extracellular matrix-mimetic poly(ethylene glycol) hydrogels engineered to regulate smooth muscle cell proliferation in 3-D

The goal of this project is to engineer a defined, synthetic poly(ethylene glycol) (PEG) hydrogel as a model system to investigate smooth muscle cell (SMC) proliferation in three-dimensions (3-D). To mimic the properties of extracellular matrix, both cell-adhesive peptide (GRGDSP) and matrix metalloproteinase (MMP) sensitive peptide (VPMSMRGG or GPQGIAGQ) were incorporated into the PEG macromer chain. Copolymerization of the biomimetic macromers results in the formation of bioactive hydrogels with the dual properties of cell adhesion and proteolytic degradation. Using these biomimetic scaffolds, the authors studied the effect of scaffold properties, including RGD concentration, MMP sensitivity, and network crosslinking density, as well as heparin as an exogenous factor on 3-D SMC proliferation. The results indicated that the incorporation of cell-adhesive ligand significantly enhanced SMC spreading and proliferation, with cell-adhesive ligand concentration mediating 3-D SMC proliferation in a biphasic manner. The faster degrading hydrogels promoted SMC proliferation and spreading. In addition, 3-D SMC proliferation was inhibited by increasing network crosslinking density and exogenous heparin treatment. These constructs are a good model system for studying the effect of hydrogel properties on SMC functions and show promise as a tissue engineering platform for vascular in vivo applications.     

Mylar and Teflon-AF as cell culture substrates for studying endothelial cell adhesion

The textured and opaque nature of Dacron and ePTFE has prevented the use of these fabrics in conventional cell culture techniques normally employed to optimize cell attachment and retention. This lack of optimization has led, in part, to the poor performance of endothelialization strategies for improving vascular graft patency. Here we show that thin, transparent films of Mylar and Teflon-AF are viable in vitro cell culture mimics of Dacron and ePTFE vascular graft materials, particularly for the study of protein mediated endothelial cell (EC) attachment, spreading and adhesion. Glass substrates were used as controls. X-ray photoelectron spectroscopy (XPS) and contact angle analysis showed that Mylar and Teflon-AF have surface chemistries that closely match Dacron and ePTFE. (125)I radiolabeling was used to quantify fibronectin (FN) adsorption, and FN and biotinylated-BSA "dual ligand" co-adsorption onto glass, Mylar and Teflon-AF substrates. Native human umbilical vein endothelial cells (HUVEC) and streptavidin-incubated biotinylated-HUVEC (SA-b-HUVEC) spreading was measured using phase contrast microscopy. Cell retention and adhesion was determined using phase contrast microscopy under laminar flow. All surfaces lacking protein pre-treatment, regardless of surface type, showed the lowest degree of cell spreading and retention. Dual ligand treated Mylar films showed significantly greater SA-b-HUVEC spreading up to 2 h, but were similar to HUVEC on FN treated Mylar at longer times; whereas SA-b-HUVEC spreading on dual ligand treated Teflon-AF was never significantly different from HUVEC on FN treated Teflon-AF at any time point. SA-b-HUVEC retention was significantly greater on dual ligand treated Mylar compared to HUVEC on FN treated Mylar over the entire range of shear stresses tested (3.54-28.3 dynes/cm(2)); whereas SA-b-HUVEC retention to dual ligand and HUVEC retention to FN treated Teflon-AF gave similar results at each shear stress, with only the mid-range of stresses showing significant difference in cell retention to Teflon-AF.     

Materials for enhancing cell adhesion by immobilization of cell-adhesive peptide.

Materials to enhance cell adhesion were synthesized by surface integration of peptide, Arg-Gly-Asp-Ser(RGDS), which is an active-site sequence of cell-adhesive proteins. Polystyrene film was glow-discharged and graft-copolymerized with acrylic acid. Then the peptide was immobilized to the poly(acrylic acid) grafts by using water-soluble carbodiimide. The cell-adhesive activity of the RGDS-immobilized film increased with increasing amount of immobilized peptide, and approached the activity of fibronectin(FN)-immobilized film. The RGDS-immobilized film was more stable against heat treatment and pH variation than the FN-immobilized film. In addition, the RGDS-immobilized film enhanced cell growth more strongly than the FN-immobilized film.