Vascular healing and integration of a fully bioresorbable everolimus-eluting scaffold in a rabbit iliac arterial model.

Abstract

We aimed to investigate a fully bioresorbable poly-l-lactide (PLLA) scaffold to assess vascular remodelling in comparison to a permanent polymeric metal DES. Twenty-five New Zealand white rabbits received an Absorb bioresorbable vascular scaffold (BVS, 1.0 and 1.1) or a CYPHER sirolimus-eluting stent (SES) in the iliac arteries. Twelve arteries were harvested at one month for scanning electron microscopy (SEM) analysis (BVS 1.1). The other implanted (BVS 1.0) arteries (n=32) were explanted at three, six and 36 months for light microscopic analysis. Re-endothelialisation assessed at one month was incomplete in both BVS and SES by SEM, with a trend towards greater coverage in SES (endothelialisation above strut: 32.2% vs. 60.6%, p=0.10). However, light microscopic analysis at later time points revealed greater endothelial coverage in BVS than in SES at 36 months (100.0% vs. 93.3%, p=0.05). Inflammation scores were comparable between arteries implanted with BVS and SES at three months (1.1 vs. 1.1, p=0.99), which decreased over time in the BVS implanted arteries (36 months: 0.0 vs. 0.2, p=0.05). At 36 months, BVS were completely resorbed, and resorption sites were replaced by connective tissue. BVS in the rabbit iliac artery model demonstrated ongoing vascular healing at three and six months, and complete vessel restoration, re-endothelialisation and no to minimal vascular inflammation at 36 months.