Comparative assessment of early neointimal formation: P8RI-coated Silk Vista versus Pipeline Vantage (Shield) in a rabbit model using optical coherence tomography.

Abstract

Background: Several coating strategies have been recently introduced to reduce thrombogenicity of flow diverters (FDs), while the P8RI coating focuses on stimulating endothelial cells for faster arterial healing. This study aims to evaluate early neointimal growth over the FD struts by comparing these two strategies in an animal model.

Methods: Bare Silk Vista (bare-SV), P8RI Silk Vista (P8RI-SV), and Pipeline Vantage with Shield technology (Shield-PV) were implanted in rabbits to treat elastase-induced aneurysms (n=6, 10, and 7, respectively) and in the aorta (n=6, 7, and 4, respectively). At 5 and 28 days, the devices were imaged with optical coherence tomography (OCT) to evaluate the stent-coverage ratio. Conventional histology and multiphoton microscopy were also performed.

Results: The aneurysm occlusion rate was similar in all three groups (P=0.577). On OCT images, the stent-coverage ratio on day 5 and day 28 (overall and at each location) was significantly higher with P8RI-SV compared with both bare-SV and Shield-PV (Kruskal-Wallis P<0.0001, Dunn post-test P<0.001 for both timepoints). Histological and multiphoton microscopy evaluations confirmed that the struts of P8RI-SV were covered by well-organized neointima expressing a high rate of collagen at the aneurysm neck and in the aorta, compatible with an advanced stage of tissue remodeling and stabilized neointima.

Conclusion: P8RI-SV demonstrated higher rates of neointimal formation covering the FD struts compared with bare-SV and Shield-PV at day 5 and day 28 in rabbits. These results confirm faster and improved arterial healing with P8RI coating; however, further studies are needed to evaluate the clinical benefits in patients.