Type I diabetes is a major risk factor for vascular complications including peripheral and coronary artery disease, cerebrovascular disease, impaired wound healing, and neuropathy. The extent of ischemic damage resulting from these complications is greatly increased by a diabetes-induced impairment in compensatory new blood vessel growth (neovascularization). Preliminary data suggest that recruitment, proliferation and assembly of bone marrow-derived endothelial progenitor cells (EPCs) into new vessels (vasculogenesis) are impaired in diabetes by multiple defects in both EPC function and trafficking. It is our central hypothesis that hypoxia is a fundamental mediator of vasculogenesis and that diabetes, by blunting the hypoxic response, leads to dysfunction in progenitor cell function, trafficking, and ischemia-induced signaling. This collaborative research project will combine the resources of a vascular biology laboratory having expertise in endothelial progenitor cell (EPC) mediated vasculogenesis (PI-Gurtner) with a biochemistry laboratory recognized for its accomplishments in delineating the cellular and molecular mechanisms of diabetic complications (PI-Brownlee). Dr. Gurtner will investigate the multiple alterations in the vasculogenic cascade induced by diabetes and Dr. Brownlee will investigate the mechanisms by which these disparate alterations are induced by hyperglycemia induced reactive oxygen species (ROS) overproduction, focusing on impairments in HIF-1alpha mediated gene transactivation. In SA 1, we will define the role hypoxia plays in mediating stem/progenitor cell function in the bone marrow niche under normal conditions. In SA 2, we will determine the impact diabetes has on progenitor cell function within this hypoxemic niche. In SA 3, we will investigate the mechanism by which diabetes affects hypoxic signaling and vasculogenesis in injured tissue. Finally, SA 4 will investigate the effects of hyperglycemia-induced ROS on HIF-1alpha stability and HIF-1alpha-mediated gene transcription during the hypoxia response. Results from the proposed studies carried out with the combined and complementary expertise of our two groups will allow for the rational development of novel strategies to restore normal compensatory vasculogenesis in diabetes, thus preventing the poor outcome of cardiovascular events (Ml, stroke, amputation) associated with the disease