Accelerated neovascularization and endothelialization of vascular grafts promoted by covalently bound laminin type 1

Development of a small diameter (<6 mm) synthetic vascular graft with clinically acceptable patency must overcome the inherent thrombogenicity of polymers and the development of neointimal thickening. Establishment of an endothelial cell lining on the lumenal surface has been hypothesized as a mechanism to improve the function of vascular grafts. The major aim of this study is to evaluate the use of laminin type 1, covalently bound to all surfaces of expanded polytetrafluoroethylene (ePTFE) grafts, on neovascularization of the interstices and lumenal surface endothelialization. One millimeter i.d. vascular grafts were surface modified through covalent attachment of laminin type 1. Grafts were subsequently implanted as interpositional aortic grafts in rats. Following 5-weeks implantation, the grafts were explanted and morphologically evaluated using scanning electron microscopy and light microscopy. Scanning electron microscopy identified an extensive coverage of antithrombogenic cells on the lumenal flow surface of laminin type 1 modified grafts. Histological evaluation confirmed the presence of endothelial cells on the midgraft lumenal surface of laminin 1 modified grafts. Extensive neovascularization of the interstices of the laminin-modified grafts occurred as compared with control grafts. We conclude that surface modification using laminin type 1 accelerates both the neovascularization and endothelialization of porous ePTFE vascular grafts.