Silicon-carbide coated coronary stents have low platelet and leukocyte adhesion during platelet activation

Background: Stent thrombosis and restenosis are of great clinical significa nce. We constructed a closed loop in vitro heparinized whole human blood ci rculation model for testing hemocompatibility of coronary stents, This mode l allows evaluation of human blood activation by blood-stent interaction in a well-controlled setting, Until now these interactions were studied in th e highly coagulable pig coronary artery model. Methods: We evaluated activation of the coagulation system and blood compon ents by uncoated, heparin-coated, and silicon-carbide coated tantalum stent s, The effects, measured by biochemical assays, were compared with stainles s-steel stents, Also the inhibitory effect on platelet activation by indome thacin equal to the oral effect of 325 mg acetylsalicylic acid daily, was m easured and visualized by scanning electron microscopy. Results: Both activation of the coagulation system and platelets were count eracted by indomethacin, suggesting an important role for platelets in acti vation of the coagulation system in this model. Despite platelet activation by all stents, the SiC-coated tantalum stent demonstrates a significantly lower GpIIIa receptor-mediated platelet adhesion at the stent surface (21.7 X 10(3) counts per second/mg stent weight) compared to all other stents (s tainless-steel 54.0, heparin-coated 95.7 and uncoated 76.2 X 10(3) cps/mg). Also activated leukocytes demonstrated a significantly loner CD11b recepto r-mediated adhesion at the SiC-coated stent (37.0 X 10(3) cps/mg) than at t he stainless-steel stent (114.5 X 10(3) cps/mg). Conclusions: Data from this in, vitro circulation study show a significantl y lower platelet and leukocyte adhesion at the surface of the SiC-coated ta ntalum stent than at the surface of stainless-steel stents or uncoated and heparin-coated tantalum stents.