Design and validation of a novel ferromagnetic bare metal stent capable of capturing and retaining endothelial cells.

Rapid healing of vascular stents is important for avoiding complications associated with stent thrombosis, restenosis, and bleeding related to antiplatelet drugs. Magnetic forces can be used to capture iron-labeled endothelial cells immediately following stent implantation, thereby promoting healing. This strategy requires the development of a magnetic stent that is biocompatible and functional. We designed a stent from the weakly ferromagnetic 2205 stainless steel using finite element analysis. The final design exhibited a principal strain below the fracture limit of 30% during crimping and expansion. Ten stents were fabricated and validated experimentally for fracture resistance. Another 10 stents magnetized with a neodymium magnet showed a magnetic field in the range of 100-750 mG. The retained magnetism was sufficiently strong to capture magnetically-labeled endothelial cells on the stent surfaces during in vitro studies. Magnetically-labeled endothelial cell capture was also verified in vivo after 7 days following coronary implantation in 4 pigs using histological analysis. Images of the stented blood vessels showed uniform endothelium formation on the stent surfaces. In conclusion, we have designed a ferromagnetic bare metal stent from 2205 stainless steel that is functional, biocompatible, and able to capture and retain magnetically-labeled endothelial cells in order to promote rapid stent healing.