Cardiovascular disease (CVD) is the leading cause of death in the USA. Increased levels of reactive oxygen species (ROS) are often associated with microvascular pathology in CVD, causing endothelial dysfunction and coronary artery disease and leading to myocardial ischemia and infarction (MI). However, failure of large clinical trials using antioxidants in patients with CVD, challenges the prevailing view that ROS production is damaging to the microvasculature. The overarching hypothesis put forth in this proposal is that EC NOX- derived ROS is beneficial for revascularization immediately following myocardial ischemia but becomes detrimental upon over the LT due to increase in mitochondrial ROS. The therapeutic benefit of intervening on ROS level is best realized by specific down regulation of mito-ROS in ECs that have been exposed to LT increase in NOX-ROS such as in DM. This hypothesis will be fully tested in vivo using our novel EC-specific transgenic MnSOD (MnSOD-OE) animals and supported using mitochondria-specific nitroxide and nanoparticle antioxidant in coronary vessels from CVD patients with DM undergoing cardiac surgery. Specific Aim 1: Elucidate the molecular mechanisms by which ST vs LT increase in EC-specific NOX-ROS (NOX-OE mouse model) exert differential effects on EC function and angiogenesis and the recovery of the post-infarct ischemic myocardium. We hypothesize that whereas ST NOX-ROS increase induces AMPK®eNOS and AMPK®CPT1-mediated increase in mitochondrial fatty acid oxidation and dNTP synthesis, LT increase in NOX-ROS results in nitro-tyrosine-induced inactivation of MnSOD, increase in mito- ROS, decrease in mito-membrane potential and dNTP synthesis leading to reduced EC proliferation. Specific Aim 2: Determine if EC-specific MnSOD overexpression protects against the detrimental effects of LT exposure of NOX-ROS on vessel density and cardiac functions in post-infarct ischemic myocardium. We hypothesize that SOD-OE will improve post-MI recovery of the cardiac function by reducing mito-ROS and improving dNTP synthesis/EC proliferation in LT NOX-OE animals and in animals with DM. Double transgenic NOX-OE:SOD-OE vs NOX-OE, and SOD-OE with DM will be examined for post-MI recovery. Specific Aim 3: Elucidate the effects of mitochondrial-targeted nitroxide antioxidant and SOD biomimetic nanoparticles on post-infarct vessel density and recovery of cardiac function in mice and on chronic myocardial ischemia in large animals (swine) with metabolic syndrome. Specific Aim 4: Determine the effects of mitochondrial-targeted nitroxide antioxidant and SOD biomimetic nanoparticles on angiogenic potential of human coronary vessels from patients with or without DM. Coronary vessels from atrial tissu...