title: Design and validation of a novel ferromagnetic bare metal stent capable of capturing and retaining endothelial cells.
abstract: 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.
authors.affiliation: Division of Engineering, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Susheil
authors.initials: S
authors.lastname: Uthamaraj
authors.forename: Brandon J
authors.initials: BJ
authors.lastname: Tefft
authors.forename: Martin
authors.initials: M
authors.lastname: Klabusay
authors.forename: Ota
authors.initials: O
authors.lastname: Hlinomaz
authors.forename: Gurpreet S
authors.initials: GS
authors.lastname: Sandhu
authors.forename: Dan
authors.initials: D
authors.lastname: Dragomir-Daescu
mesh_terms: D015906:Angioplasty, Balloon, Coronary; D000818:Animals; D003331:Coronary Vessels / Q000033:anatomy & histology; D042783:Endothelial Cells; D004867:Equipment Design; D005290:Ferric Compounds / Q000737:chemistry; D060328:Magnetic Phenomena; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry; D008856:Microscopy, Fluorescence; D009354:Neodymium; D013193:Stainless Steel; D015607:Stents; D013552:Swine
chemical_list: D005290:Ferric Compounds; D013193:Stainless Steel; C000499:ferric oxide; D009354:Neodymium