Investigation of MC3T3-E1 cell behavior on the surface of GRGDS-coupled chitosan

The GRGDS (Gly-Arg-Gly-Asp-Ser) peptide has intermediate affinity to alphaVbeta3 and alphaIIbbeta3, which are the integrins most reported to be involved in bone function. In this study, biomimetic chitosan films modified with GRGDS peptide were prepared and were used as a substrate for the in vitro culture of MC3T3-E1 cells in order to investigate the effect of GRGDS modification on MC3T3-E1 cell behavior. The results of electron spectroscopy for chemical analysis (ESCA), attenuated total reflection-Fourier transform infrared spectra (ATR-FTIR), and amino acid analysis (AAA) demonstrated that the chitosan films were successfully modified with GRGDS peptides and that the surface density of the immobilized GRGDS was on the order of 10(-9) mol/cm2. The immobilization of the GRGDS sequence on chitosan as well as the peptide concentration play a significant role in MC3T3-E1 cell behavior. MC3T3-E1 cell attachment, proliferation, migration, differentiation, and mineralization were remarkably greater on GRGDS-coupled chitosan than on unmodified chitosan. Besides, the degree of acceleration of these biological processes was found to be dependent on peptide density. Competitive inhibition of MC3T3-E1 cell attachment using soluble GRGDS peptides indicated that the interaction of MC3T3-E1 cells with the surface of the materials was ligand-specific. Cytoskeleton organization in the fully spread MC3T3-E1 cells was highly obvious on GRGDS-coupled chitosan when compared to the lack of actin fibers noted in the round MC3T3-E1 cells on unmodified chitosan. These results suggest that MC3T3-E1 cell function can be modulated, in a peptide density-dependent manner, by the immobilization of GRGDS peptide on chitosan used for scaffold-based bone tissue engineering.