An extracellular matrix–like surface modification on titanium improves implant endothelialization through the reduction of platelet adhesion and the capture of endothelial progenitor cells

To address the problem of surface-induced thrombosis and restenosis, an extracellular matrix–like biological membrane was constructed from collagen, heparin, vascular endothelial growth factor, and an anti-CD34 antibody. This membrane was assembled on a titanium surface using a layer-by-layer self-assembly technique and induced the spontaneous endothelialization of synthetic cardiovascular implants in vivo. The multilayer growth process was carried out by first depositing a single layer of positively charged poly-L-lysine on the negatively charged NaOH-treated titanium substrate. This was followed by alternating depositions of negatively charged heparin, containing vascular endothelial growth factor and an anti-CD34 antibody and positively charged collagen, terminating with an outermost layer of heparin containing vascular endothelial growth factor and the anti-CD34 antibody. The uncoated and coated titanium samples were exposed to platelet-rich plasma and endothelial progenitor cells, respectively, under static and flow conditions in vitro. Then, the samples were implanted into dog femoral arteries. The results suggest that the multilayering process led to reduced platelet adhesion and activation, promoted the attachment and growth of endothelial progenitor cells in vitro, and induced the rapid and complete endothelialization of the lumenal surface of the implant. Thus, the approach described here may be used in the fabrication of titanium-based vascular implant surfaces to induce endothelialization in vivo.