Gelatin coating enhances flow diverting stent endothelial cell coverage, parent vessel healing and aneurysm occlusion

<jats:p>Background: Flow diversion stent treatment of cerebral aneurysms has demonstrated high rates of aneurysm occlusion and long-term durability. However, complete endothelization of the flow diverting stent is required for parent vessel healing which closes the aneurysm and metal stent from the circulation. Therefore, stent coatings which enhance endothelial migration and attachment may increase the rate of aneurysm occlusion and reduce complications associated with flow diversion treatment. Here we investigate the use of gelatin as a stent surface coating to enhance the rate of stent endothelialization and coverage and increase aneurysm healing. Methods: Nitinol- Neuroform stents (Stryker, Kalamazoo, MI) and cobalt-chromium- Pipeline Flex flow diverting stents (Medtronic, Minneapolis, MN) were used for this study. The stents were coated with gelatin and endothelial cell attachment, proliferation and stent coverage were determined in vitro and compared to uncoated stent controls. A rabbit elastase-aneurysm model was used to determine the effects of endothelial cell seeded-gelatin coated flow diverting stents on aneurysm obliteration and parent vessel healing. Results: In vitro, gelatin coating of nitinol stents did not significantly alter endothelial cell attachment, proliferation, or stent coverage. However, gelatin coating of cobalt-chromium stents significantly increased endothelial cell attachment, proliferation and migration. In fact, gelatin coating significantly (p&lt; 0.001) increased the rate of complete stent endothelization by 33% compared to unmodified controls. In vivo, treating aneurysm with endothelial cell seeded-gelatin coated stents resulted in aneurysm occlusion in 8 of 8 (100%) rabbit aneurysms at 90 days compared to only 4 of 7 (57%) in unmodified controls (p&lt; 0.001). Histologically, there were trends in increased neoarterial wall thickness across the aneurysm neck and neointimal formation in the parent artery. Angiographic assessment demonstrated strong parent and side branch patency. Conclusions: Gelatin coating enhances EC attachment and stent coverage which is dependent upon the type of stent. Endothelial cell seeded-gelatin coated-flow diverting stents allowed 100% aneurysm obliteration and neoarterial formation without affecting side branch patency or parent artery perfusion. Gelatin coating therefore represents a valuable strategy to enhance stent cellularization and aneurysm occlusion rates.</jats:p>