Cold drawn bioabsorbable ferrous and ferrous composite wires: An evaluation of in vitro vascular cytocompatibility

Abstract

A systematic approach is applied to quantify the impact of bioabsorbable metals on human vascular endothelial cells (EC) and aortic smooth muscle cells (SMC) with the aim of optimizing bioabsorbable endovascular stent development. Composite wires comprising novel combinations of Fe, Mn, Mg, and Zn were produced and fabricated into tubular mesh stents. The stents were incubated with primary EC in order to assess attachment and cell proliferation. Migration of SMCs from the vessel medial wall to the target lesion site following recanalization of an atherosclerotic artery is important in the process of neointimal hyperplasia. Metal ion species were assayed for their impact on cell migration and survival at concentrations ranging from 0.037 to 10mM. An MTT-based assay was used to assess cytotoxicity after insult with various metal ion concentrations. Fe2+ and Fe3+ ion species were found to repress the migration of SMCs across a porous polycarbonate track etch membrane at concentrations of 1mM. Mn2+ promoted SMC migration at a concentration of 1mM, however, this effect was quenched when Fe2+ was included. Mg2+ was found to significantly increase SMC migration at concentrations above 1mM. Cell survival was not reduced after 24h insult with concentrations of Mg2+ up to 10mM. LD50 concentrations of greater than 1mM were found for Mg2+, Fe2+, Fe3+, and Fe2+ with 35 wt.% Mn2+. Significantly greater numbers of EC attached to bioabsorbable metal species compared with 316L stainless steel. Good EC coverage and proliferation were observed for all tested materials up to 120h.