Development of novel covered stents using salmon collagen

In this study, we newly developed self-expandable or balloon-expandable covered stents with a biodegradable salmon collagen (SC) film. The SC-covered stents were fabricated by placing a bare stent in a mixture of acidic SC solution and a fibrillogenesis-inducing buffer (pH 6.8) including a cross-linking agent (water-soluble carbodiimide), and subsequent incubation at 4°C for 24 h and lyophilization. The stents obtained were completely covered with an SC film having a nanofibrous structure (fibril diameter, about 70 nm). On immersion in water, the film is converted to a gel with slight swelling. There was no rupture of the SC cover after mounting on a balloon catheter or after expansion. Preliminary implantation was conducted by placing the balloon-expandable covered stents in the common carotid arteries of beagles. One month after implantation, angiography showed that all stented arteries were patent with no significant neointimal thickening. In conclusion, SC is potentially useful as a cover material of endovascular stents to enhance patency.