Development and biocompatibility of a novel corrodible fluoride-coated magnesium-calcium alloy with improved degradation kinetics and adequate mechanical properties for cardiovascular applications

Recently, corrodible magnesium-based alloys have been introduced for use as cardiovascular stents and orthopedic implants. However, rapid corrosion rates have raised questions about their biocompatibility. Therefore, we developed a binary fluoride-coated magnesium-calcium alloy with improved degradation kinetics. Biocompatibility of the alloys was evaluated with metabolic assays (color-metric WST-1 test). Furthermore, five different probes of magnesium-calcium alloys (MgCa 0.4, 0.6, 0.8, 1.2, and 2.0 wt %) were cocultivated with human smooth muscle cells and endothelial cells. To investigate the decomposition kinetics in a physiological environment the alloys were used untreated and fluoride coated (MgF2). Mg and Ca decreased the metabolic activity in vascular cells dose-dependently, with cytotoxic effects only at unphysiological concentrations. Uncoated magnesium alloys showed signs of decomposition after a short incubation time of 24 h in contrast to MgF2 coated alloys. After 10 days smooth muscle and endothelial cells around the alloys were still alive, whereas colonization of the surfaces was only observed for smooth muscle cells. The fluoride-coated MgCa alloys exhibited good results concerning mechanical properties, degradation kinetics, and biocompatibility in vitro. We conclude that a binary fluoride magnesium-calcium alloy is a promising candidate for the production of cardiovascular stents. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res 93A: 763-775, 2010