Biocompatibility of pure iron: In vitro assessment of degradation kinetics and cytotoxicity on endothelial cells

Pure iron is a candidate material for coronary artery stents because of its biodegradable and nontoxic properties. However the degradation characteristics of pure iron in vivo and in vitro are not yet clear. The purpose of the work described here was to determine the degradation rate of pure iron in vitro and to characterize the interaction of individual corrosion products from biocorrodible iron stents with endothelial cells (ECs) from the adjacent tissue. Pure iron was immersed in simulated body fluids (SBF) solution and the mass loss was measured. The response of human ECs to various concentrations of ferrous ions was investigated using WST-8 assay. The results demonstrate that the mean degradation rate of iron in vitro is about 20.4 μg/(cm2 h). The lower iron concentration (< 10 μg/ml) may produce the favorable effect on the metabolic activity of ECs. Conversely, the very high iron ion concentration (> 50 μg/ml) may have cytotoxicity on ECs.