Bioengineering cobalt chromium cardiovascular stent biomaterial for biofunctionalization

Abstract

Suboptimal biocompatibility of cardiovascular stents manifest as non-compliance at stent-artery interface in vivo. We optimized a plasma-activated coating (PAC) technology to modify cobalt chromium alloy L605 (PAC-L605) surface of an implantable coronary stent material, for improved biofunctionalization. The PAC-L605 surfaces displayed covalent binding capacity of a protein candidate tropoelastin (TE) by retaining 70.3% of TE after SDS detergent washing. Human coronary artery endothelial cell (HCAEC) proliferation visualized with crystal violet staining, did not vary significantly among the biomaterials at 3 or 5 days. Anchorage of cell cytoskeleton visualized with immunofluorescence and scanning electron microscopy (SEM), showed homogenous cell morphology on PAC/TE (with TE) surfaces. Surface hemocompatibility was assessed with static and flow blood assays, the hydrophilic PAC-L605 displayed lower clot formation compared to L605. Area of surface fibrinogen deposited was significantly lower on PAC-L605 vs. L605. Selected ISO 10993-4 tests for biological evaluation of medical devices in contact with blood indicated significantly lowered plasma markers of thrombin-antithrombin complex (TAT), beta-thromboglobulin ({beta}-TG), soluble P-selectin and soluble terminal complement complex (SC5b-9) on PAC-L605 vs. L605. There was no significant difference for plasma biomarkers of polymorphonuclear elastase (PMN elastase) on PAC-L605 vs. L605. Improved surface biofunctionalization of implantable cardiovascular materials could be achieved by plasma-activated coating (PAC).