Constructing bio-functional layers of hyaluronan and type IV collagen on titanium surface for improving endothelialization

Abstract

Surface modification of cardiovascular devices with biological molecules has been generally accepted as a promising method of treating in-stent thrombosis and hyperplasia. Therefore, a novel layer composed of hyaluronan (HA) and type IV collagen (CoIV) was prepared on titanium (Ti) for the purpose of promoting vascular smooth muscle cells contractile phenotype previously. However, endothelialization as another important function of the modified layer has not been investigated. Thus, in this study, HA as the solvent, the bio-functional layers fabricated with the CoIV concentration of 200 μg/ml (200M) and 500 μg/ml (500M), respectively, which possessed better anti-hyperplasia property, were chosen for the endothelialization test. The endothelial cell (EC) adhesion and proliferation experiment showed that the 200M layer, 500M layer, and the single CoIV layer significantly improved the ECs growth compared with the Ti and single HA layer, and the ECs on the 500M layer had larger major/minor index and cell spreading areas which were related to the EC functions. The functional factor release results showed that ECs on the 500M layer release more nitric oxide, prostacyclin, thrombomodulin, and tissue factor pathway inhibitor compared to ECs on the other surfaces. The result of ECs shedding experiment under blood flow shear stress indicated that the retention of ECs on 200M layer, 500M layer, and the single CoIV layer was remarkably larger than the value of the other groups, but it seemed that several parts of the ECs layer on the single CoIV surface disappeared under BFSS, and this may lead to the occurrence of in-stent thrombosis and atherosclerosis, so 200M layer and 500M layer were considered as possessing the best function of anti-EC-shedding. We hope this research can provide more helpful exploration and application for enhancing endothelialization of the cardiovascular stents.