Long-term assessment of a novel biodegradable paclitaxel-eluting coronary polylactide stent.

Abstract

The aim of this study was to assess technical feasibility, biocompatibility, and impact on coronary stenosis of a new biodegradable paclitaxel-loaded polylactide stent. Due to high rates of in-stent restenosis and permanent nature of metal stent implants, synthetic polymers have been proposed as surrogate materials for stents and local delivery systems for drugs. Paclitaxel was shown to inhibit vascular smooth muscle cell proliferation and migration. A novel biodegradable double-helical stent was manufactured using controlled expansion of saturated polymers (CESP) for the moulding of a bioresorbable poly(D,L)-lactic acid (PDLLA). A modified balloon catheter for stent deployment was developed according to the mechanical stent properties. Twelve paclitaxel-loaded (170 microg) polylactide stents, 12 unloaded polylactide stents, and 12 316L bare metal stents were deployed in porcine coronary arteries of 36 animals. Six pigs of each group were sacrificed after 3 weeks and 3 months, respectively, for every setting. Drug release kinetics as well as histomorphometrical and histopathological analyses were performed. A slow paclitaxel release kinetic for more than 2 months and therapeutic tissue concentrations were demonstrated. Coronary stenosis after implantation of paclitaxel-loaded stents (30+/-5% or 49+/-4%) was significantly inhibited compared to unloaded PDLLA stents (65+/-10%, P=0.021 or 71+/-4%, P=0.004) and metal stents (53+/-6% or 68+/-8%, P=0.029 and P=0.020) after 3 weeks or 3 months. Early complete endothelialisation was shown. Nevertheless, a local inflammatory response to the polylactide as a result of the polymer resorption process was observed. This novel polylactide stent showed sufficient mechanic stability, and by incorporation of paclitaxel, a significant potential to reduce restenosis development after vascular intervention was seen.