Hypercholesterolemia Impairs Stem Cell-Mediated Post-Ischemic Neovascularization

描述（由申请人提供）：外周动脉疾病是残疾和肢体丧失的主要原因，其本身导致心血管和全因死亡率大幅增加，其患病率和病死率超过艾滋病。PAD的主要生理反应是侧支动脉扩张，这是动脉发生的一种形式。我们的研究计划的长期目标是阐明负责侧支动脉扩张的细胞和分子机制以及心血管危险因素损害这一过程的机制。我们实验室最近的工作表明，造血干细胞（hsc）是侧支动脉扩张的主要决定因素，高胆固醇血症损害了许多hsc依赖的缺血后新生血管机制。项目假设：高胆固醇血症诱导的氧化应激通过表观遗传机制，限制造血干细胞向血管细胞和促血管生成单核细胞的分化，并使造血干细胞向促炎症单核细胞的分化倾斜，从而减弱缺血后新生血管的形成。具体目标1：确定高胆固醇血症诱导的氧化应激对缺血后新生血管形成过程中hsc向血管细胞分化的影响。特异性目的2：确定高胆固醇血症诱导的氧化应激对缺血性新生血管形成后HSC向促血管生成单核细胞中间体、CD11blow和Ly6C低群体分化的影响。特异性目标3：确定调节HSC对高胆固醇血症诱导的氧化应激反应的表观遗传机制，并在缺血后新生血管形成过程中损害其向促血管生成单核细胞的分化。为了实现这些目标，我们将建立体外分化试验，作为识别和纠正高胆固醇血症诱导的HSC功能障碍的表观遗传变化的框架。体内移植模型将使我们能够识别表观遗传依赖的临床

DESCRIPTION (provided by applicant): Peripheral arterial disease is a major cause of disability and limb loss and itself carries a substantial increase in cardiovascular and all-cause mortality, such that its prevalence and case fatality rate exceeds that for AIDS. The principle physiological response to PAD is collateral artery enlargement, a form of arteriogenesis. The long-term goals of our research program are to elucidate the cellular and molecular mechanisms responsible for collateral artery enlargement and the mechanisms by which cardiovascular risk factors impair this process. Recent work in our laboratory shows that hematopoietic stem cells (HSCs) are a primary determinant of collateral artery enlargement and hypercholesterolemia impairs many of the HSC-dependent mechanisms of post-ischemic neovascularization. The Project Hypothesis of this grant is: Hypercholesterolemia-induced oxidant stress, through epigenetic mechanisms, restricts the differentiation of HSCs towards vascular cells as well as towards pro-angiogenic monocytes and rather skews their differentiation towards pro-inflammatory monocytes thereby attenuating post-ischemic neovascularization. We will test our Project Hypothesis with the following Aims: Specific Aim 1: Determine the effect of hypercholesterolemia-induced oxidant stress on HSCs differentiation into vascular cells during post-ischemic neovascularization. Specific Aim 2: Determine the effects of hypercholesterolemia-induced oxidant stress on HSC differentiation towards pro-angiogenic monocyte intermediates, CD11blow and Ly6C low populations during post-ischemic neovascularization. Specific Aim 3: Identify the epigenetic mechanisms which regulate the HSC response to hypercholesterolemia- induced oxidant stress and impairs their differentiation towards pro-angiogenic monocytes during post-ischemic neovascularization. To accomplish these aims, we will establish in vitro differentiation assays that will serve as a framework to identify and correct the epigenetic changes responsible for hypercholesterolemia-induced HSC dysfunction. In vivo transplantation models will allow us to identify epigenetic-dependent clinical consequences of hypercholesterolemia-induced HSC oxidant stress. We will also utilize these in vivo models to reverse hypercholesterolemia- induced impairments in HSC function as preclinical studies intended to evaluate new therapeutic interventions. We will also assess the impact of hypercholesterolemia on human HSC function in vitro and utilize advanced humanized mouse models for in vivo studies, thereby increasing the scientific and clinical impact of our studies. Finally, we will utilize multiple techniques to identify the epigenetic marks induced in HSCs by hypercholesterolemia on a genome-wide scale. We believe that the results of these studies will introduce novel scientific findings that will be of substantial clinical impact.