Biofunctionalization of titanium with PEG and anti-CD34 for hemocompatibility and stimulated endothelialization

Thrombosis and restenosis are the main causes of failure of cardiovascular and other blood-contacting biomedical devices. It is recognized that rapid endothelialization is a promising method for preventing these complications. Convincing evidence in vivo has further emerged that the vascular homing of endothelial progenitor cells (EPCs) contributes to rapid endothelial regeneration. This study deals with improving the hemocompatibility and enhancing EPC colonization of titanium by covalently bonding PEG(600) or PEG(4000), then end-grafting of an anti-CD34 antibody. For this, a chemically hydroxylated titanium surface was aminosilanized, which was further used for covalent grafting of polyethylene glycol and the antibody. The grafting efficiency was verified in each step. In vitro platelet adhesion analysis confirmed superior hemocompatibility of the modified surface over the control. Affinity of EPC to the surface and inhibition of smooth muscle cell adhesion, two prerequisites for endothelialization, are demonstrated in in vitro cell culture. While the coating selectively stimulates EPC adhesion, its antifouling properties prevent formation of an extracellular matrix and proliferation of the cells. Additional affinity for matrix proteins in the coating is considered for further studies. Potent inhibitory effect on macrophage activation and the relative stability of the coating render this technique applicable.