A novel polymer‐free paclitaxel‐eluting stent with a nanoporous surface for rapid endothelialization and inhibition of intimal hyperplasia: Comparison with a polymer‐based sirolimus‐eluting stent and bare metal stent in a porcine model

Hypersensitivity and inflammatory responses to polymers may be responsible for late stent thrombosis after implantation of a drug-eluting stent (DES). Polymer-free DES may reduce the prevalence of these adverse reactions in vessels. We evaluated a polymer-free paclitaxel-eluting-stent with a nanoporous surface (nano-PES) for endothelialization and inhibition of neointimal hyperplasia by optical coherence tomography (OCT) and pathology in a porcine model. Nano-PES with high-dose (HD) and low-dose (LD) paclitaxel (1.0 μg/mm2 and 0.4 μg/mm2, respectively) was compared with a sirolimus-eluting stent (SES) and bare-metal stent (BMS) in a porcine model. Fifty-three stents (14 HD, 14 LD, 14 SES, 11 BMS) were implanted in 18 minipigs. At 14 days, nano-PES with HD and LD showed more complete endothelialization compared with SES. BMS had 100% endothelial coverage. At 28 days, a significant reduction in neointimal hyperplasia was detected by OCT in the nano-PES HD group compared with BMS. No benefit in prevention of the neointimal hyperplasia was observed in the nano-PES LD group. Nano-PES stents showed decreased deposition of fibrin and inflammation compared with SES. Pharmacokinetic studies revealed that nano-PES could effectively deliver the drug to the local coronary artery and it released the drug more rapidly than SES. Such a release profile was favorable for rapid endothelialization of nano-PES. The present study showed the nano-PES to be a new drug-delivery technology; that it used a nanoporous stent surface; that it offered desirable drug-elution properties without the use of polymers; that it may translate into an improved safety profile for next-generation DES. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.