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

Aims: We aimed to investigate a fully bioresorbable poly-l-lactide (PLLA) scaffold to assess vascular remodelling in comparison to a permanent polymeric metal DES. Methods and results: Twenty-five New Zealand white rabbits received an Absorb bioresorbable vascular scaffold (BVS, 1.0 and 1.1) or a CYPHER (R) 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. Conclusions: 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.