Regulation of endothelial cell function by GRGDSP peptide grafted on interpenetrating polymers

Vascular endothelium plays an important role in preventing thrombogenesis. Bioactive molecules such as fibronectin-derived peptide Gly-Arg-Gly-Asp-Ser-Pro (GRGDSP) can be used to modify the surface of cardiovascular implants such as vascular grafts to promote endothelialization. Here we conjugated GRGDSP peptide to the non-fouling surface of an interpenetrating polymer network (IPN), and investigated the effects of the immobilized GRGDSP molecules on EC functions under static and flow conditions at well-defined GRGDSP surface densities (similar to 0 to 3 pmol/cm(2)). EC adhesion and spreading increased with 2 GRGDSP surface density, reached a plateau at 1.5 pmol/cm(2) and increased further beyond 2.8 pmol/cm(2). Cell adhesion and spreading on GRGDSP induced two waves of extracellular signal-regulated kinase (ERK) activation, and 0.2 pmol/cm(2) density of GRGDSP was sufficient to activate ERK. EC proliferation rate was not sensitive to GRGDSP surface density, suggesting that cell spreading at low-density of GRGDSP is sufficient to maintain EC proliferation. EC migration on lower-density GRGDSP-IPN surfaces was faster under static condition. With the increase of GRGDSP density, the speed and persistence of EC migration dropped quickly (0.2-0.8 pmol/cm(2)) and reached a plateau, followed by a slower and gradual decrease (1.5-3.0 pmol/cm(2)). These data suggest that the changes of EC functions were more sensitive to the increase of GRGDSP density at lower range. Under flow condition with shear stress at 12 dyn/cm(2), EC migration was inhibited on GRGDSP-IPN surfaces, which may be attributed to the assembly of large focal adhesions induced by shear stress, suggesting a catch-bond characteristic for RGD-integrin binding. This study provides a rational base for surface engineering of cardiovascular implants. (c) 2007 Wiley Periodicals, Inc.