Effects of Metabolic Disorders on Bone Marrow-Derived Cell Function

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DESCRIPTION (provided by applicant): Diabetes, obesity, and dyslipidemia are epidemic in the U.S. and are associated with increased risk for stroke, myocardial infarction, peripheral vascular disease, and foot ulcers. Thus, there is immense need for better therapies to stimulate vascular growth in the treatment of these conditions. Bone marrow-derived cells (BMDCs) are being developed as therapeutic agents in this application. Unfortunately diabetes and metabolic syndrome damage BMDCs rendering them at best modestly pro- and at worst, anti-angiogenic. So, maximization of the therapeutic efficacy of BMDCs may require manipulation of the BMDCs or adjunct therapies. To accomplish this requires an understanding of molecular mechanisms of action of BMDCs and identification of factors that modulate their effectiveness. In studies of healthy mice and Leprdb mice (i.e., diabetic mice with metabolic syndrome) we identified four molecules, tumor necrosis factor alpha (TNF1), interleukin 12 (IL-12), monocyte chemoattractant factor 1 (MCP-1), and vascular endothelial growth factor A (VEGF-A) that share a common regulatory pathway that appears to regulate BMDC mediated vascular growth. This study will define the role of these molecules and their downstream targets in BMDC mediated tissue vascularization. Our aims are to determine if a reduction in the ability of BMDCs to 1) secrete TNF1, IL-12, or MCP-1; 2) induce TNF1, IL-12, or MCP-1; or 3) induce downstream targets of TNF1, IL-12, or MCP-1 limits their capacity to promote growth of capillaries, arterioles, or collaterals. The effects of the loss of these factors on BMDC induced vascular growth will be studied in the ischemic hindlimb and skin wound models in Leprdb mice and chimeric Leprdb mice whose bone marrow has been replaced with cells from and TNF1, IL-12, or MCP-1 knockout mice. By treating mice with BMDCs from healthy, TNF1, IL-12, or MCP-1 knockout mice and performing rescue experiments we will identify 1) which of the studied factors are critical for BMDC mediated growth and 2) which might be used therapeutically as adjuncts to BMDC therapy in patients with poorly functioning BMDCs. BMDCs are already in use in early phase clinical trials, but there is little understanding of why cell therapy succeeds in some and fail in other patients. Our ultimate goals are to understand this dichotomy, to provide a more rational basis for selecting patients who are likely to benefit from BMDC therapy, and identify possible adjunct therapies to potentiate the effects of BMDCs in those whose own BMDCs provide little therapeutic benefit. PUBLIC HEALTH RELEVANCE: This work could lead to better treatment of heart attacks, strokes, and burns as well as prevention of chronic ulcers, particularly in people who are obese and those with diabetes.