Cardiovascular disease has been associated with increased levels of reactive oxygen species (ROS). Recently, we have shown that a critical balance between cytosolic ROS and mitochondrial ROS is crucial in cardiovascular health and that modulation of mitochondrial ROS helps prevent detrimental effects of cytosolic ROS on endothelial cells (EC) in transgenic animals. Here, we report the development of a controlled delivery system for a mitochondria-targeted antioxidant, JP4-039, from an electrospun scaffold made of FDA-approved biocompatible polymeric nanofibers. We demonstrate that the active antioxidant moiety was preserved in released JP4-039 for over 72 h using electron paramagnetic resonance. We also show that both the initial burst release of the drug within the first 20 min and the ensuing slow and sustained release that occurred over the next 24 h improved tube formation in human coronary artery ECs (HCAEC) in vitro. Taken together, these findings suggest that electrospinning methods can be used to upload mitochondrial antioxidant (JP4-039) onto a biocompatible nanofibrous PLGA scaffold, and the uploaded drug (JP4-039) retains nitroxide antioxidant properties upon release from the scaffold, which in turn can reduce mitochondrial ROS and improve EC function in vitro. Cardiovascular disease, including ischemic heart disease and myocardial infarction (MI), is the leading cause of death in the world. One of the major consequences of MI is death of cardiomyocytes leading to cardiac remodeling, fibrosis, and heart failure [1]. There are major efforts undergoing to improve blood supply to the ischemic myocardium by inducing the growth or sprouting of new blood vessels, that is, angiogenesis, from the existing coronary vessels. Recent work from our laboratory and others showed that reactive oxygen species (ROS) plays a major role in determining coronary vascular endothelial cell (EC) proliferation, migration, and tube formation in vitro [2-5]. ECs have several intracellular sources for ROS, including membrane-bound NADPH oxidases, mitochondria, peroxisome, and cytochrome P450 [6-12]. Whereas the increase in ROS is believed to be harmful for the cardiovascular system, the use of global