Magnetizable Duplex Steel Stents Enable Endothelial Cell Capture

Emerging medical nanotechnology applications often utilize magnetic forces to guide the movement of superparamagnetic particle linked cells and drugs in order to achieve a therapeutic effect. Superparamagnetic particle labeled endothelial cells have previously been captured on the surface of prototype nickel-plated stents in proof of concept studies. Facilitated endothelialization may help improve the healing of stented arteries and reduce the risk of stent thrombosis and restenosis. Extensive evaluation of candidate materials led to the development of a magnetizable 2205 duplex stainless steel stent. Magnetic field strengths of approximately 630 mG were induced within these stents by holding them in close proximity to a 0.7 T rare earth magnet. The magnetic field strength was reliably maintained over several days, but was partially reduced upon mild mechanical shock or plastic deformation. Mechanical testing demonstrated that stents could withstand crimping and expansion necessary for vascular implantation; however, magnetic field strength was significantly reduced. When placed in an endothelial cell suspension of 1×10⁶ cells/mL, magnetized stents captured approximately 310 cells/mm² compared to approximately 35 cells/mm² for non-magnetized control stents. These data provide quantitative support to the observation that low level magnetization of stents may be adequate to attract labeled, autologous, blood-derived endothelial outgrowth cells following stent placement. This, in turn, may lead to more rapid and complete healing of stented arteries with a concomitant improvement in stent performance.