Transcriptomics of adherent endothelial cells for improved endothelialization of small-diameter vascular grafts

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Project Summary The long-term objective of this study is to establish an autologous endothelium on the blood-contacting surface of implantable cardiovascular devices. This is critically important for providing hemocompatibility and minimizing the risk of thrombosis, embolism, and other adverse outcomes in order to improve patient safety. This objective directly supports the mission of the NHLBI to promote the treatment of heart diseases and enhance the health of all individuals so that they can live longer and more productive lives. Many cardiovascular diseases are treated with implantable devices. While lifesaving, these devices also carry an inherent risk of thrombosis and embolism that requires administration of anticoagulation therapy. The proposed study addresses the dire clinical need for establishing an endothelium within small-diameter vascular grafts. Patients with coronary heart disease who require bypass surgery currently undergo autologous vessel harvest because synthetic grafts demonstrate poor patency in small-diameter applications. Autologous vessel harvest is associated with additional cost and significant donor site morbidity. In addition, a large and growing number of patients do not possess suitable autologous vessel for reasons including preexisting vascular disease, vein stripping, and previous harvest. Establishment of an autologous endothelium on small-diameter bypass grafts is necessary for achieving acceptable patency rates without autologous vessel harvest. The goal of the proposed research is to improve endothelial cell retention on vascular graft biomaterials by identifying novel molecular signaling targets for molecular modulation strategies to promote cellular adhesion strength. This is driven by our hypothesis that differential regulation of molecular signaling pathways involved in cellular adhesion is responsible for a subpopulation of endothelial cells resisting detachment upon implantation. Specific Aim 1 will identify molecular signaling pathways responsible for allowing a subpopulation of endothelial cells to remain adherent upon exposure to physiological shear stress. RNA-sequencing will be used to compare the transcriptome of all cells and adherent cells. The transcriptomics data will be used to identify molecular signals that are highly differentially regulated in adherent cell subpopulations. Specific Aim 2 will develop and test strategies to improve endothelial cell retention on vascular graft biomaterials. A molecular modulation strategy will be developed to enhance cell adhesion by upregulating or downregulating critical signaling molecules as appropriate. Cell retention will be compared under conditions of physiological shear stress. Specific Aim 3 will assess the biological performance of small-diameter vascular grafts seeded with endothelial cells using a preclinical model. The most promising cell adhesion enhancement strategy will be used to endothelialize grafts, which will be implanted into the carotid circulation of swine and analyzed for clinically relevant outcomes including cell retention, patency, thrombosis, neointimal hyperplasia, and inflammation.