Endothelial cell distribution on the surface of anodized Ni-Ti stent struts after the flow exposure

抄録

Stent is currently widely used to treat cardiovascular diseases, such as stenosis and aneurysm. Endothelial cells (EC), the components of vascular endothelium, denudation during stent implementation leave the risk of severe complication known as restenosis. Restenosis could re-block the vessel lumen lead to the failure of stenting treatment. To prevent restenosis, surface treatment to enhance the stent surface biocompatibility has been made to accelerate the process of EC migration onto to the stent, known as stent endothelialization. Anodization on nitinol is a simple and efficient approach to improve biocompatibility of nitinol stent surface by enhancing the surface hydrophilicity, thus increasing the EC activities. Researchers found that EC activities could be affected by the blood flow. The implanted stent structure could disturb the flow environment near the EC layer cause the EC dysfunctions, then leading to restenosis. Therefore, it is important to study the EC activities on the nitinol stent surface with anodization treatment under the flow conditions. To realize that this research performed the flow exposure experiment for 24 hours. A parallel plate flow chamber was designed to generate constant wall shear stress (WSS) to the EC monolayer. Nitinol stent strut with anodization was placed within the flow chamber. EC attachment and morphology on the surface of stent strut were then observed. The static experimental conditions were chosen as the control. The result found that EC density on the surface of anodized stent strut was higher than the non-treated stent under both with and without flow conditions. EC density under the static conditions was higher than the flow conditions. Comparing with the static conditions, EC morphology was found as long and thin in the response to the flow stimuli. Anodization could enhance the EC migration onto the nitinol stent strut surface by improving the surface hydrophilicity. Therefore, the anodization surface treatment method might accelerate the stent endothelialization process. The improvement of surface hydrophilicity may could be reduced under the flow conditions.