Design and testing of magnetic vascular stents for rapid endothelialization

Abstract

Rapid endothelialization of cardiovascular stents by means of magnetic cell capture has the potential to enhance healing and to reduce the risk of restenosis. We designed and manufactured stents made of magnetizable 2205 duplex stainless steel (UNS S31803) to study the magnetic field strength required to capture endothelial cells labeled with superparamagnetic nanoparticles. To aid in the design, we used the finite element method to study stress and strain distributions and to ensure strain values do not exceed 30% during crimping and expansion. Stents magnetized with a permanent magnet exhibited magnetic fields in the range of 630 mG compared to 10 mG for non-magnetized stents as measured by a magnetoresistive probe. Furthermore, we observed that plastic deformation greatly reduced the magnetic field strength, but did not result in material fracture. Finally, endothelial cell capture studies revealed that approximately 310 cells/mm2 were attracted to the magnetized stents within 1-3 minutes.