Influence of Topography of an Endovascular Stent Material on Smooth Muscle Cell Response

The phenotypic shift of smooth muscle cells (SMCs) from contractile to synthetic phenotype after endovascular stenting has been deemed to be the predominant cause of restenosis. Although substrate topography has been shown to affect SMC response for a variety of polymers, effect of topography on phenotype of SMCs has not been well studied for endovascular stent materials. Thus, the objective of the present study was to evaluate SMC phenotype, manifested in morphology, proliferation, and contractile marker smooth muscle α-actin expression, as a function of 316L stainless steel topography. Results of this study showed that the cells grown on micro-grooved surface (groove depth: 13 μm) were significantly more elongated than those on the electropolished surface. Ascertained by repeated proliferation studies, cells grown on micro-grooved surface demonstrated a significantly lower proliferation rate relative to the electropolished surface. An enhanced expression of smooth muscle α-actin grown on micro-grooved surface was also found near confluence. Furthermore, cells on electropolished surface demonstrated a substantial loss of smooth muscle α-actin between days 1 and 4. Therefore, given the favorable SMC response reported in this study, our findings suggest that a micro-grooved topography might prove beneficial for endovascular stent applications.