Engineering integrin‐specific surfaces with a triple‐helical collagen‐mimetic peptide

Abstract

Integrin‐mediated cell adhesion to extracellular matrix proteins anchors cells and triggers signals that direct cell function. The integrin α 2 β 1 recognizes the glycine‐phenylalanine‐hydroxyproline‐glycine‐glutamate‐arginine (GFOGER) motif in residues 502–507 of the α 1(I) chain of type I collagen. Integrin recognition is entirely dependent on the triple‐helical conformation of the ligand similar to that of native collagen. This study focuses on engineering α 2 β 1‐specific bioadhesive surfaces by immobilizing a triple‐helical collagen‐mimetic peptide incorporating the GFOGER binding sequence onto model nonadhesive substrates. Circular dichroism spectroscopy verified that this peptide adopts a stable triple‐helical conformation in solution. Passively adsorbed GFOGER‐peptide exhibited dose‐dependent HT1080 cell adhesion and spreading comparable to that observed on type I collagen. Subsequent antibody blocking conditions verified the involvement of integrin α 2 β 1 in these adhesion events. Focal adhesion formation was observed by immunofluorescent staining for α 2 β 1 and vinculin on MC3T3‐E1 cells. Model functionalized surfaces then were engineered using three complementary peptide‐tethering schemes. These peptide‐functionalized substrates supported α 2 β 1‐mediated cell adhesion and focal adhesion assembly. Our results suggest that this peptide is active in an immobilized conformation and may be applied as a surface modification agent to promote α 2 β 1–specific cell adhesion. Engineering surfaces that specifically target certain integrin–ligand interactions and signaling cascades provides a biomolecular strategy for optimizing cellular responses in biomaterials and tissue engineering applications. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 511–523, 2003