Differences of platelet adhesion and thrombus activation on amorphous silicon carbide, magnesium alloy, stainless steel, and cobalt chromium stent surfaces

Abstract

Coronary stenting is considered to be the gold standard of percutaneous coronary interventions, because stents are able to reduce early and late elastic recoil (negative remodeling) and restenosis in comparison with balloon angioplasty alone. It is known that stent thrombogenicity and neointimal formation are determined by the surface characteristics of the stent platform, electrochemical features of the stent surface, and the degree of degradation after implantation. Metallic stents coated with amorphous silicon carbide and biodegradable stents made of magnesium alloy have been introduced clinically, but there are no data available comparing the biocompatibility of these novel stent materials with conventional stents. We demonstrate simple and reproducible in vitro methods assessing the rate of platelet adhesion and thrombus activation for biocompatibility tests of different stent surfaces. We show that amorphous silicon carbide and magnesium alloy stent surfaces markedly lower the rate of platelet adhesion and platelet/fibrin activation when compared with uncoated stainless steel or cobalt chromium alloy surfaces. Semiconductor materials on the stent surface reduce platelet and fibrin activation by increasing the critical electron gap to greater than 0.9 eV resulting in a lower electron transfer out of the stent material. Passive stent coatings with specific semiconducting properties such as amorphous silicon carbide or magnesium alloy reduce thrombogenicity and may improve biocompatibility of a stent platform.