Influence of surface topography on endothelialization of intravascular metallic material

PURPOSE: To determine whether grooves on a metal surface help endothelialization and, furthermore, what groove size is more likely to promote the fastest endothelialization in an in vitro model. Hypothetically, a microscopic pattern of parallel grooves disposed in the direction of flow, on the inner surface of stents, increases endothelial cell migration rates, resulting in decreased time to total coverage of the prosthetic surface. MATERIALS AND METHODS: Square, flat pieces of nitinol were placed level on a monolayer, confluent culture of endothelial cells. The metal pieces were treated to produce parallel grooves on the surface of 1, 3, 15, and 22 mu m to be compared to polished, smooth controls. Microscopy images were obtained by digital capture and processed for analysis of migration distance and cell count, density, shape, and alignment. RESULTS: Grooved surfaces promoted increased rate of migration of endothelial cells, up to 64.6% when compared to smooth, control surfaces. Larger grooves resulted in greater migration rates. The cells aligned with the grooves, elongated, and become more numerous on grooved surfaces, particularly with large grooves. CONCLUSION: A pattern of microscopic parallel grooves more than doubles the migration rate of endothelial cells over metallic surfaces ordinarily used for endovascular stents. Future research in this area is aimed at demonstrating the potential effect of grooved endovascular stent surfaces on faster endothelialization times.