Cell adhesion to extracellular matrices plays central roles in development and the formation, maintenance and repair of numerous tissues. Moreover, cell adhesion to adsorbed proteins or adhesive sequences engineered on surfaces is important to biomaterials, tissue engineering, and biotechnological applications. Cell adhesion to extracellular matrix proteins is primarily mediated by the integrin family of adhesion receptors. In addition to anchoring cells, supporting cell spreading and migration, integrins provide signals that direct cell survival, proliferation, and differentiation. Because of the critical importance of cell adhesion, biomimetic strategies have focused on generating surfaces that present short bioadhesive motifs, such as the integrin-binding site arginine-glycine-aspartic acid (RGD) in fibronectin (FN), to promote cell adhesion. While these engineered supports promote adhesive activities in vitro, healing responses in in vivo models have been marginal. Our group has shown that integrin binding specificity can direct specific cell fates including proliferation and differentiation. We have recently developed a surface-initiated polymerization procedure to grow dense poly(oligoethylene glycol methacrylate (poly(OEGMA)) brushes on clinically relevant titanium substrates that affords nonfouling properties, yet can be easily functionalized to peptide ligands. We used this system to examine the contribution of integrin binding specificity to osseointegration.
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