Endothelial Cell Attachment and Proliferation Studies on Modified Metal Stent Surfaces
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1236-SS04-03
Endothelial Cell Attachment and Proliferation Studies on Modified Metal Stent Surfaces Vipul Davé1, Charito Buensuceso2, David Colter2, Jonathon Zhao1 and Robert Falotico1 1 Cordis Corporation, Warren, NJ 07059 2 Advanced Technologies and Regenerative Medicine, Somerville, NJ 08876
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 study shows that heparin covalently coated on a stent surface to provide antithrombotic properties did not generate 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. INTRODUCTION Drug eluting stents have transformed the practice of interventional cardiology and are the treatments of choice for patients with symptomatic coronary artery disease undergoing percutaneous intervention. There are risks of stent thrombosis due to late reendothelialization, poor stent deployment, and premature anti-platelet therapy discontinuation (1). There are different approaches to modify surfaces of bioprosthesis to improve blood and tissue biocompatibility (2-6). If stent surface modifications can enhance cell attachment and proliferation, then it will improve healing, minimize thrombus formation, reduce long term dual antiplatelet therapy, and improve stenting in high risk patients. The hypothesis for this research is to investigate the effect on endothelial cell attachment due to topographical and chemical changes on metal stent surfaces. In this study, physical and chemical modifications were made to flat coupons prepared from cobalt chromium alloy (CoCr) which were evaluated for endothelial cell attachment and proliferation.
EXPERIMENT Materials Flat coupons (5 mm x 5 mm) were prepared from a sheet (thickness = 0.088 mm) of L605 metal alloy with compositions specified in ASTM F 90. Primary components of the alloy were cobalt (47%), chromium (21%), tungsten (16%) and nickel (11%). Since major components of the alloy
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