Decreased platelet adhesion and enhanced endothelial cell functions on nano and submicron-rough titanium stents

Endothelialization of a vascular stent is a critical step to prevent late stent thrombosis. In this study, electron beam deposition was utilized to create different scales of roughness on titanium stents, including flat features (F-Ti), a mixture of nanometer and submicron features (S-Ti), and nanometer features (N-Ti). The role of stent surface roughness on initial protein adsorption, platelet adhesion, rat aortic endothelial cell adhesion, migration, and nitric acid/endothelin-1 secretion was investigated in vitro. Results revealed the highest endothelial cell attachment on S-Ti after 4 h. Moreover, under flow conditions, the endothelial cell layer remained the most intact on S-Ti. These results were positively correlated with improved vitronectin adsorption on S-Ti. Endothelial cells also showed the fastest migration on S-Ti of all the samples over a 96 h time period. Endothelial cells on S-Ti exhibited the highest nitric acid/endothelin-1 ratio of all the samples, indicating potentially the best antithrombic endothelial cellular phenotype. This study also revealed the lowest platelet adhesion on S-Ti of all the samples. In summary, without using pharmaceutical agents, significantly less platelet and greater endothelial responses on nanometer to submicron rough titanium were observed in this study compared to flat titanium and, thus, nanometer to submicron surface features on titanium should be further studied for vascular stent applications.