Improved Neo-Endothelialization of Small Diameter ePTFE Grafts with Titanium Coating

Abstract

Background Patency of small synthetic bypass grafts is inferior compared to autologous grafts for revascularization procedures. Titanium coating of foreign surfaces has shown to decrease thrombogenicity, enhance biocompatibility and promote adhesion of endothelial cells. The aim of this study was to test the effect of titanium coating of small diameter ePTFE grafts on short term patency, neo-endothelialization and neointimal proliferation. Methods Bilateral carotid graft interposition was performed in 5 pigs with uncoated (n=5) and titanium-coated (n=5) ePTFE grafts (internal diameter=4 mm, length=5 cm), thus each pig served as its own control. At the end of the study (30 ± 3 days), patency and stenosis severity was assessed by carotid angiography. Animals were sacrificed and grafts were excised for histology and scanning electron microscopy. Morphometry of histologic sections was carried out to determine neointimal proliferation and percentage of neo-endothelial coverage. Results Patency rate was 80% for uncoated and titanium-coated grafts. Quantitative angiography did not show any significant difference in lumen size between two groups. Morphometry revealed a significantly higher cellular coverage with CD 31 positive endothelial cells for titanium-coated (84 ± 19%) than uncoated grafts (48 ± 26%, p<0.001). There was a non significant trend (p=0.112) towards increased neointimal proliferation in titanium-coated (94 ± 61 μm2/μm) compared to uncoated grafts (60 ± 57 μm2/μm). Conclusions Patency rate in uncoated and titanium-coated ePTFE grafts is similar at one month. However, titanium coated grafts show a significant improvement in neo-endothelialization compared to uncoated grafts.

Human Blood Vessel–Derived Endothelial Progenitors for Endothelialization of Small Diameter Vascular Prosthesis

“…However, adhesion and growth of endothelial cells over these biomaterial surfaces is the most crucial step, which limits the use of small diameter vascular grafts for cardiac bypass surgery. Coating of synthetic grafts with different proteins, peptides or metals [10], [11], [13], [48] has been reported. However, endothelialization of small diameter prosthesis has remained a major problem that limits the use of these synthetic vascular grafts in cardiac bypass surgeries.…”

“…However synthetic vascular grafts do not spontaneously endothelialize in situ because of their nonconductive characteristics towards endothelial cells adhesion, cell spreading and growth. Surface modification of ePTFE tubes so as to make them suitable for adhesion and growth of autologous endothelial cells for better endothelialization and patency of ePTFE grafts has been examined in various in vitro and in vivo models [10]–[13]. Though such synthetic vascular grafts are non-immunogenic they demonstrate increased platelet aggregation/thrombosis and stenosis as compared to autologous vessels, especially when their diameter is small [14].…”

Bio- And Hemocompatible Tissue-Engineered Polycaprolactone Scaffolds Seeded by Human Endothelial and Smooth Muscle Cells After Implantation in the Abdominal Aorta of Scid Mice

“…В артериаль-ной позиции клеточно-заселенные конструкции имели достаточную механическую прочность и проходимость до 26 недель [29,30]. Причем эти материалы не уступают по срокам проходимости ПТФЭ [31,32].…”

A Reproducible Porcine ePTFE Arterial Bypass Model for Neointimal Hyperplasia

“…Currently described porcine restenosis models with prosthetic materials include variations of arteriovenous and arterio-arterial bypass grafts [17][18][19][20][21][22][23]. The arterio-venous bypass graft represents a different pathophysiologic process that results in neointimal hyperplasia when compared to arterial reconstruction [24].…”

“…These two models should be considered as two distinctly different models evaluating two entirely different processes. It should also be mentioned that there are ePTFE interposition graft models that have been described [17,18]. For the most part, these models are also inappropriate, as arterial interposition grafts are rarely placed in patients in the lower extremity.…”