Background : Coronary stents are used clinically with great benefit for

 cardiovascular disease  patients. Recently cerebral stents have been reported excellent outcomes in patients with acute intracranial occlusions in whom other recanalization methods have failed. However several problems exist after cerebral stents implantation. Especially cerebral hemorrhage and in-stent thrombosis are critical complications due to thrombogenecity of metallic stent. Purpose of this study is to develop a new anti-thrombogenic cerebral stent using ion beam surface modification to solve critical complications

Method : Thirty self-expanding metallic mesh stents were fabricated from Ti-Ni metal wire with a dimension of 4mm(D) x 25mm(L) x 0.15mm(T). Twenty stents were coated with type-1 collagen and irradiated with a He+ ion beam(ion stent group). Ten stents had no treatment(non-ion stent group).

The stents were implanted into the right and left femoral arteries of 15 beagle dogs. Heparin(100units/kg) was administered intravenously before implantation. Following stents implantation, no anti-platelet or anti-coagulant drugs were administered.  

Results : The 1-month patency rate for the non-ion stent group was 10%(1/10) and for the ion stent group was 80%(16/20). P=0.0004 by Fisher’s exact test. Six ion stents ware extracted to make  histopathologic examination with thin neointima formation. Ten stents remain patent after 5 years implantation with no  anti-platelet or anti-coagulant drugs. Scanning electron microcopy showed that the neointima surface was covered with a complete confluent layer of endothelial-like cells.

Conclusion : A He+ ion-implanted collagen coated Ti-Ni self-expanding stents provides excellent anti-thrombogenisity and biocompatibility. This “next-generation” ion stent offers a promising new cerebral stent.