Polyglycolic acid surface modification by bi-functional peptide to improve endothelial cell adhesion and biological functions

Bioresorbable scaffolds such as polyglycolic acid are employed in a number of clinical and tissue engineering applications, because they can be remodeled to form native tissue over time. However, polyglycolic acid does not attract endothelial cell adhesion, and therefore must be chemically treated to enable cells to bind and grow on its surface. The goal of this research is to investigate a novel approach to modify PGA surfaces to enhance initial endothelial cell attachment and spreading and increase initial cell retention under physiological shear stress on PGA surfaces.;To achieve this goal, we designed a hetero-bifunctional peptide linker, termed "interfacial biomaterial". This peptide couples a surface affinity domain with a biologically active domain that provides appropriate biological cues and promotes desired cellular behaviors on the modified surfaces. Surface affinity peptides for PGA were selected by screening phage display libraries with a direct-infection procedure developed in this project. One such polyglycolic acid affinity domain then was coupled to the integrin binding domain, arginine-glycine-aspartic acid to build a chemically synthesized bimodular 27 amino acid peptide. This peptide mediated interactions between polyglycolic acid and integrin receptors on endothelial cells. The adhesion constant, surface thickness, and viscoelastic properties of this peptide on polyglycolic acid surfaces were characterized. Cell binding studies were conducted to examine the peptide influence of cell adhesion, spreading, and cytoskeletal re-organizations under static conditions. Endothelial cell surface integrin studies proved the peptide-endothelial cell interactions were through integrin mediated adhesion. Finally, initial cell retention on interfacial biomaterial-treated polyglycolic acid surfaces was studied to examine the peptide's ability to retain human endothelial cells on PGA surfaces under physiological shear stress. Significantly higher shear stress, 67 dyn/cm2, was needed to achieve 90% cell retention on spin-coated polyglycolic acid surfaces modified by this peptide than the same retention on unmodified surfaces, 4 dyn/cm2, or fibronectin-coated polyglycolic acid surfaces, 19 dyn/cm2. This interfacial biomaterial mediated adhesion of endothelial cells on PGA was in an integrin-dependent manner. The studies also demonstrated that the interaction particular between alpha vbeta3 and the peptide was crucial at high shear stress on interfacial biomaterial modified polyglycolic acid surfaces.;This research demonstrates that engineered peptides can enhance human endothelial cell adhesion, spreading, and initial retention onto PGA surfaces by eliciting biological behaviors normally associated with much larger structures such as the extracellular matrix, and also verify the effectiveness of bifunctional peptide approach.