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，因此其患病率和病死率超过了艾滋病。PAD的主要生理反应是侧支动脉扩张，这是动脉生成的一种形式。我们研究计划的长期目标是阐明侧支动脉扩大的细胞和分子机制，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）是侧支动脉扩大的主要决定因素，高胆固醇血症损害了缺血后新生血管形成的许多HSC依赖性机制。该资助的项目假设是：高胆固醇血症诱导的氧化应激，通过表观遗传机制，限制了HSC向血管细胞以及促血管生成单核细胞的分化，而是使其向促炎单核细胞分化，从而减弱缺血后的新血管形成。我们将测试我们的项目假设与以下目标：具体目标1：确定高胆固醇血症诱导的氧化应激对HSC分化为血管细胞在缺血后新生血管形成的影响。具体目标二：确定缺血后新血管形成期间高胆固醇血症诱导的氧化应激对HSC向促血管生成单核细胞中间体、CD 11 blow和Ly6C低群体分化的影响。具体目标3：确定调节HSC对高胆固醇血症诱导的氧化应激的反应并在缺血后新血管形成期间损害其向促血管生成单核细胞分化的表观遗传机制。为了实现这些目标，我们将建立体外分化试验，作为一个框架，以确定和纠正负责高胆固醇血症诱导的HSC功能障碍的表观遗传变化。体内移植模型将使我们能够识别表观遗传依赖的临床 高胆固醇血症诱导的HSC氧化应激的后果。我们还将利用这些体内模型来逆转高胆固醇血症诱导的HSC功能损伤，作为旨在评价新的治疗干预的临床前研究。我们还将评估高胆固醇血症对体外人HSC功能的影响，并利用先进的人源化小鼠模型进行体内研究，从而增加我们研究的科学和临床影响。最后，我们将利用多种技术在全基因组范围内鉴定高胆固醇血症在HSC中诱导的表观遗传标记。我们相信，这些研究的结果将引入新的科学发现，将产生重大的临床影响。

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.