Endothelial Cell Attachment and Proliferation Studies on Modified Metal Stent Surfaces

Abstract

Flat coupons prepared from cobalt chromium alloy (CoCr) were modified using different methods (low energy excimer laser processing, electron beam irradiation, and immobilized covalently-bound heparin coating). Human coronary artery endothelial cell (HCAEC) attachment and growth kinetics were investigated on unmodified and modified metal surfaces. Results showed that HCAEC attach to unmodified CoCr coupons and surface-modified CoCr coupons. No change in cell number was observed when cells were grown on CoCr coupons and heparin coated coupons throughout the 72h study period. A decrease in cell number was observed for excimer treated coupons. HCAEC seeding on CoCr stents indicated that cells attached and proliferated on the stents over a ten day study period. This research showed that physical modifications did not improve cell proliferation. Very few non-viable cells were observed for unmodified and surface bound heparin coupons, and cells attached to the surface up to 72h. This shows that heparin can be coated on a stent surface to provide anti-thrombotic properties without any negative effect on cell attachment and proliferation. In vitro screening method of testing endothelial cell attachment and proliferation on modified metal stent surfaces can be used to gain insight for developing next generation drug eluting stents with improved endothelialization behavior.