The preclinical study of biocompatibility of tyrosine polycarbonate bioresorbable scaffold in small caliber porcine peripheral arteries

Drug-eluting resorbable scaffolds (DRS) are conceptually attractive for treatment of peripheral arterial disease, particularly below-the-knee. MOTIV is a peripheral variant of REVA Medical's well-established, radiopaque tyrosine-polycarbonate (Tyrocore) sirolimus-eluting DRS. The purpose of this study was to provide imaging and histopathologic data on vascular response to MOTIV in porcine peripheral arteries. MOTIV scaffolds (3.0 or 3.5 × 12/24/36/48/60 mm) were implanted in 20 internal iliac arteries of 9 Yorkshire swine. At 30 and 90 days, vascular stenosis, strut coverage, and strut apposition were characterized using optical coherence tomography. Scaffold structure and vascular healing were assessed by histopathology and scanning electron microscopy. At termination, all vessels remained patent. The average neointimal thickness was 0.22 ± 0.05 mm in Group 1 (30 days) and 0.18 ± 0.10 mm in Group 2 (90 days); the percent area stenosis was 28 ± 6% and 24 ± 11%, respectively. All struts were fully covered by neointima. No malapposition, stent fracture or late strut discontinuity was observed. Adequate vessel wall healing at both time points was characterized by a typically fully mature neointima and complete reendothelialization at all sites. No unresorbed luminal thrombus was observed. The inflammation scores were low for all vessels on both time points, except for one animal. The average inflammation (excluding multinucleated giant cells [MNGCs]) was 0.6 (MNGCs score was 0.9) for the stented vessel segments at 30 days and 0.8 (MNGCs score of 1.0) at 90 days. Implantation of the MOTIV up to 60 mm long in small-caliber peripheral arteries of swine resulted in 100% patency rate and adequate vascular healing at 30-day and 90-day timepoints. The Tyrocore-based DRS retained the necessary structural integrity throughout the course of the study and confirmed their favorable biocompatibility in small-caliber porcine peripheral arteries.