Endothelium is endowed with several biologically active molecules to protect vascular integrity and maintain vascular hemostasis. Prostacyclin (PGI2) is one of the important vasoprotective molecules. It inhibits platelet activation and aggregation, suppresses smooth muscle cell activation and migration, and inhibits monocyte activation. It also diminishes vasoconstrictor responses. Reduced local PGI2 synthesis due to endothelial injury may lead to excessive blood and vascular cell activation thereby accelerating thrombosis and neointimal proliferation. Systemic administration of PGI2 to augment local PGI2 concentration has limited success because of undesirable adverse effects. The applicant proposes to test whether local production of PGI2 at a damaged vascular site can be restored by gene transfer of PGI2 synthetic enzymes and the augmented local PGI2 synthesis can protect against vascular thrombosis. Biosynthesis of PGI2 from arachidonic acid (AA) is catalyzed by prostaglandin H synthase (PGHS, also called cyclooxygenase) which converts AA into PGG2 and than PGG2 to PGH2. PGH2 is further converted to PGI2 by prostacyclin synthase (PGIS). In preliminary studies, this group has shown that endothelial cell PGHS-1 levels are augmented by retrovirus- and adenovirus-mediated transfer of human PGHS-1 cDNA which is accompanied by a large increase in PGI2 synthesis. Administration of adenovirus-CMV-PGHS-1 into angioplasty-damaged pig carotid arteries resulted in a 5-fold increase in PGI2 synthesis. To further the investigation of vascular gene transfer, 5 specific aims are proposed: 1) to evaluate the effect of adenovirus-mediated prostaglandin H synthase-1 (PGHS-1) transfer on preventing thrombosis in experimental animal models; 2) to assess the effect of transfer of endothelial prostacyclin synthase (PGIS) alone and in combination with PGHS-1 gene on the extent and duration of PGI2 production in cultures endothelial cells in vitro and on preventing thrombosis in vivo; 3) to determine the effect of PGHS-1 and/or PGIS gene transfer on intimal hyperplasia in experimental animal models; 4) to evaluate non-viral vectors for transferring PGHS-1 and/or PGIS cDNAs for augmenting PGI2 synthesis in vasoprotection; and 5) to use the most effective of the above gene therapies and determine its efficacy in preventing thrombosis and intimal proliferation in atherosclerotic porcine coronary arteries.
