The role of hypoxia in venous neointimal hyperplasia in hemodialysis grafts

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DESCRIPTION (provided by applicant): Project description: More than 400,000 patients in the US have end stage renal disease (ESRD), a population expected to double in the next decade. The long term goal of this current proposal and research program is to improve the care of patients with ESRD, the vast majority of who use long-term hemodialysis as their mode of renal replacement therapy. These patients require highly functioning vascular access for optimal therapeutic adequacy. Hemodialysis vascular access failure is frequently from venous stenosis secondary to neointimal hyperplasia (VNH). Preliminary data from our studies indicate that several mechanisms may be responsible for VNH formation. These include: 1) Elevated hypoxia inducible factor-1 alpha (HIF-11) which then stimulates; 2) Increased expression of vascular endothelial growth factor-A (VEGF-A) and its receptors; 3) Increased expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 (gelatinases); and 4) Proliferation and migration of fibroblasts from the adventitia and media to the intima resulting in VNH formation. We have developed state- of-the art molecular reagents and validated mouse nephrectomy with arteriovenous fistula model (AVF) and a hypoxia fibroblast cell culture model. The in vitro and in vivo models and accompanying reagents allow us to rigorously test our Central Hypothesis: Venous neointimal hyperplasia occurs when increased HIF-11 stimulates adventitial fibroblasts to differentiate into myofibroblasts (1-SMA positive cells). Increased expression of HIF-11 regulated proteins including VEGF-A, MMP-2 and MMP-9 results in the proliferation and migration of myofibroblasts into the intima leading to the formation of VNH. To test our central hypothesis we have developed three specific aims: 1). Determine the temporal and spatial role(s) of VEGF-A in VNH. 2). Determine the role(s) and regulation of MMPs in VNH. 3). Determine if the molecular mechanism of hypoxia induced fibroblast to myofibroblast differentiation is mediated by the VEGF- A/MMP axes. Successful completion of these aims will allow us to ultimately translate therapies aimed at inhibiting VNH to clinical trials thereby improving patient outcomes using commercially available anti-VEGF-A antibodies (Avastin (Bevacizumab)) and MMP inhibitors (Simvastatin or Sirolimus) which can be delivered using catheter based technology. PUBLIC HEALTH RELEVANCE: Public Health Relevance Statement: More than 400,000 patients in the US have end stage renal disease (ESRD), a population expected to double in the next decade. The long term goal of this current proposal and research program is to improve the care of patients with ESRD, the vast majority of who use long-term hemodialysis as their mode of renal replacement therapy.