Biomimetic Engineering of Vascular Prostheses

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DESCRIPTION (provided by applicant): Cardiovascular disease, including coronary artery disease, stroke and peripheral arterial disease, is the leading cause of mortality in the United States. There is an urgent clinical need for a readily available, small diameter (<5 mm ID) vascular prosthesis to treat atherosclerotic vascular disease. The main impediments to successful implementation of vascular graft prostheses are the lack of rapid endothelialization, along with thrombosis and intimal hyperplasia (IH). To address these problems, we propose to develop a novel, ready- to-implant biomimetic modification of commercially available small diameter ePTFE grafts that will encourage rapid in vivo endothelialization and healing without stimulating thrombosis and without the need for endothelial cell (EC) pre-seeding. Our overall hypothesis is that EC function on small diameter vascular grafts can be controlled by utilizing peptides with high affinity and specificity for EC surface receptors in a biomimetic surfactant polymer that will also suppress platelet adhesion and graft thrombosis, and that a biodegradable adventitial/medial extracellular matrix (ECM) mimetic polymer gel system will encourage smooth muscle cell (SMC) incorporation and healing within the graft, without stimulating IH. Specific Aim 1 will focus on EC function on biomimetic fluorosurfactant polymers with coupled cell binding ligands that are selective for EC and not platelets on ePTFE and model fluoro-silane surfaces. The biomimetic polymer enables control over the density and spatial distribution of peptide ligands. The pendant ligands will include cyclic RGD peptides that demonstrate high affinity and specificity for 1v23 (compared to 1IIb23), REDV peptide with specificity for 1421, CRRETAWAC peptide specific for 1521, and heparin binding peptides that demonstrate specificity for syndecans. EC functions to be measured include adhesion, proliferation, migration, cytoskeletal organization, gene expression, shear stability, inflammatory state, and hemostasis, as well as competitive interactions with platelets. Aim 2 focuses on investigating EC function on biomimetic polymers utilizing combinations of vascular-specific cell-binding peptides and carbohydrates. In Aim 3, we propose to develop a biodegradable ECM-mimetic gel polymerized around ePTFE fibrils and designed to support SMC incorporation, contractile phenotype, and healing within the graft. The polymer gel will incorporate RGD, and SMC-binding 1-dystroglycan and laminin peptides presented on pendant dendrons. SMC-binding functionalities will be studied in the gel alone, and when incorporated into the interstices of an ePTFE vascular prosthesis. In Aim 4, we plan to validate that EC-specific biomimetic polymers are successful in modulating in vitro EC function and able to function in an in vitro perfusion system and in a chronic in vivo small-diameter vascular graft porcine model. Successful completion of these aims will result in the development of a biomimetic ePTFE prosthesis suitable for longer-term animal and clinical studies.Cardiovascular disease, including coronary artery disease, stroke and peripheral arterial disease, is the leading cause of mortality in the United States (1-3), To help address this major public health problem, there is an urgent clinical need for a readily available, biofunctional small diameter (<5 mm ID) arterial replacement (vascular graft prosthesis) to treat atherosclerotic vascular disease. The main impediments to successful vascular graft prosthesis are the lack of rapid endothelialization, thrombosis and intimal hyperplasia. The proposed research will address these problems, through the development of a novel, ready-to-implant biomimetic small diameter graft that will encourage rapid in vivo endothelialization and healing without stimulating thrombosis. Successful completion of the research will provide biomimetic vascular graft prosthesis suitable for clinical studies.