Development of a new hybrid biodegradable drug-eluting stent for the treatment of peripheral artery disease

Abstract

Background: Despite the superior benefits of nitinol metal stents, there are several major concerns regarding their metallic components in the treatment of peripheral artery disease (PAD). However, there is little clinical data available on the use of biodegradable stents for treating PAD and limited experimental trials investigating the development of new models of biodegradable stents. Purpose: The purpose of this study was the development of a new biodegradable stent for PAD that could provide sufficient radial force to maintain patency, flexibility, and long-term patency. Methods: All self-expandable hybrid biodegradable stents were designed using a knitting structure composed of poly-L-lactic acid (PLLA) and nitinol. Four different types of stents were implanted in 20 iliac arteries in 10 mini pigs: a bare-metal stent (BMS) (Group 1, n=5), a drug-free hybrid stent (Group 2, n=5), a 50% (50:100, w/w) paclitaxel (PTX)/poly-lactide-co-glycolic acid (PLGA) (fast PTX-releasing form) hybrid stent (Group 3, n=5), and a 30% (30:100, w/w) PTX/PLGA (slow PTX-releasing form) hybrid stent (Group 4, n=5). We performed angiography after each stent implantation as well as follow-up angiography and intravascular ultrasound (IVUS) at 4 and 8 weeks. Histologic specimens were analyzed at the experimental end point. Results: All stents were successfully implanted in all animals. In a comparison of Groups 1, 2, 3, and 4, less diameter stenosis was observed in Group 4 when compared with the other groups at the 4-week follow-up on angiographic analysis (19.0±12.7% vs. 39.3±18.1% vs. 46.8±38.0% vs. 4.8±4.2%, respectively; p=0.032). IVUS findings further suggested that the neointima of Group 4 tended to be lesser than that of the others. The stent area measured by IVUS did not show significant changes at the 8-week follow-up. In histologic analysis, lower vascular traumas and inflammatory reactions were observed in Group 4. Conclusions: Our new biodegradable 30% PTX/PLGA (slow-releasing form) stent showed more favorable results for patency and safety when compared with the other stent types. This study provides new concepts for developing a new biodegradable stent for the treatment of PAD.