Experimental Evaluation of a New Antithrombogenic Stent Using Ion Beam Surface Modification

A new antithrombogenic stent using ion beam surface modification nanotechnology was evaluated. The ion stent is being developed to inhibit acute and chronic stent-related thrombosis. Thirty self-expanding mesh stents were fabricated from Ti-Ni metal wires with a dimension of 4 mm (diameter) × 25 mm (length) × 0.15 mm (thickness). Twenty stents were coated with type I collagen and irradiated with a He⁺ ion beam at an energy of 150 keV with fluences of 1 × 10¹⁴ ions/cm² (ion stent group). Ten stents had no treatment (non-ion stent group). The self-expanding stents were implanted into the right and left peripheral femoral arteries of 15 beagle dogs (vessel diameter approximately 3 mm) via a 6Fr catheter under fluoroscopic guidance. Heparin (100 units/kg) was administered intravenously before implantation. Following stent implantation, no antiplatelet or anticoagulant drugs were administered. The 1-month patency rate for the non-ion stent group was 10% (1/10), and for the ion stent group it was 80% (16/20) with no anticoagulant or antiplatelet drugs given after stent implantation ( P  = 0.0004 by Fisher's exact test). Ten stents remain patent after 2 years in vivo with no anticoagulant or antiplatelet drugs. These results indicate that He⁺ ion-implanted collagen-coated Ti-Ni self-expanding stents have excellent antithrombogenicity and biocompatibility. This ion stent is promising for coronary and cerebral stent applications.