In vitro biocompatibility analyses of stents coated with diamond-like carbon by flow cytometry, cell growth assays and electron microscopy

Background: Coronary artery stents can induce platelet activation by shear forces and contact to the biomaterial. This activation is one important tri gger for thrombosis. Coating of stents is a possible approach to prevent th is side effect. The purpose of this study was to evaluate in vitro the bioc ompatibility of stents coated with diamondlike carbon (DLC). Materials and Methods: For in vitro testing, DLC-coated stents were compared with noncoat ed 316L stainless steel stents. For this purpose, cell culture assays, vide omorphometric, electron microscopic and flow-cytometric techniques were app lied. Results: Growth assays with smooth muscle cells and endothelial cells revealed that DLC did not affect proliferation rates and did not have cyto toxic effects. Video-based morphometry and scanning electron microscopy sho wed an ultrasmooth surface and homogenous expansion patterns of the DLC ste nts. For analysis of platelet antigens in a circulating loop model, flow cy tometry was applied. Our experiments showed no significant changes in mean channel fluorescence intensity for the structural antigens CD41a (p = 0.6) and CD42b (p = 0.1). In contrast, the expression of the activation-dependen t antigens CD62p and CD63 increased significantly in noncoated stents compa red to DLC-coated stents (p < 0.05). Conclusion: Coating of intracoronary s tents with DLC significantly reduces platelet activation. Hereby, biocompat ibility is improved.