Macrophage responses to vascular stent coatings

Diamond-like carbon (DLC) films have been proposed as potential coatings for blood-contacting devices. In this study, tetrahedral amorphous carbon (ta-C) films deposited by filtered cathodic vacuum arc system (FCVA) were compared with commercially deposited polyurethane coatings (PU) and uncoated stainless steel samples. X-ray reflectivity (XRR) measurements were performed to check density and thickness of the ta-C coatings, and contact angles measurements were used to assess surface wettability. J774 macrophages were used to assess the cell responses to the materials. Cell number, metabolic activity, and hydrogen peroxide production were measured by using biochemical assays, and the cell attachment and morphology were determined by using scanning electron microscopy and confocal laser scanning microscopy. Wettability measurements showed that of the materials, the stainless steel was the most hydrophilic, and the ta-C coatings were the most hydrophobic. Although the initial attachment and morphology did not appear to be dependent on the wettability, the cell numbers did increase with increasing wettability. Macrophages on the stainless steel samples were the most active in producing hydrogen peroxide. These data show that ta-C samples performed as well as commercial PU-coated samples in blocking cell reactions to the substrate and may prove to be effective coatings for blood-contacting materials.