Stem Cell Mobilization in Diabetes

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DESCRIPTION (provided by applicant): This proposal outlines a translational research plan to investigate the role of stem/progenitor cell (SPCs) mobilization and recruitment for healing diabetic neuropathic lower extremity ulcers. Techniques will involve blood cell flow cytometry, histochemistry on wound biopsies, and a novel method for measuring endothelial nitric oxide synthase (eNOS) activity in intact platelets. As a tool to hasten SPCs mobilization from the bone marrow we will use hyperbaric oxygen (HBO2), which stimulates bone marrow eNOS activity. We hypothesize that eNOS activity is impaired in diabetics and that improved glucose management will improve eNOS activity, SPCs mobilization from the bone marrow, SPCs recruitment to wounds, and these changes will stimulate wound healing. Specific aim 1. To document eNOS activity as a variable for SPCs mobilization in diabetics. Trials will be carried out with diabetics and normal, healthy adults. The primary focus is to test whether platelet eNOS activity correlates with baseline number of circulating SPCs and HBO2-mediated SPCs mobilization. A secondary goal is to examine whether eNOS activity is correlated with glycemic control. Specific aim 2. To assess feasibility of evaluating wound variables associated with neo-vascularization and whether they correlate with healing in diabetic patients. This study will involve populations of diabetics with neuropathic ulcers of varying severity who are undergoing clinical treatments according to current recommended guidelines. In a sub-set of patients with refractory wounds, this includes hyperbaric oxygen. We will examine how clinical practices influence eNOS activity, circulating SPCs, and biochemical characteristics within wounds including the presence of growth factors, proteases and inhibitors of proteases. SPCs recruitment and biochemical characteristics will be compared between the existing neuropathic ulcer and an acute punch biopsy wound. We hypothesize that better management of diabetes will improve eNOS activity, and that wound healing rate depends on the number of circulating SPCs and biochemical factors within the wound that influence SPCs homing and function. These studies will be carried out by a multidisciplinary team. Information obtained will provide a foundation for a multi-centered clinical trial to test whether diabetic management can modulate SPCs mobilization and recruitment to wounds, whether eNOS activity is correlated with these changes, and whether diabetic ulcer healing is related to these improvements. PUBLIC HEALTH RELEVANCE: This proposal outlines a research plan to investigate the role of stem/progenitor cell (SPCs) mobilization and recruitment for healing diabetic neuropathic lower extremity ulcers. We hypothesize that endothelial nitric oxide synthase (eNOS) activity is impaired due to diabetes and glucose management. As a tool to stimulate mobilization of SPCs from the bone marrow we will use hyperbaric oxygen (HBO2), and we will determine how clinical management practices - including HBO2 - modify circulating SPCs as well as wound characteristics.