Angiogenesis in a model of diabetes and endothelial dysfunction

描述（由申请人提供）：美国有超过3500万人患有糖尿病和葡萄糖耐受不良。与非糖尿病个体相比，这些个体发生心血管事件的风险高达8倍，使心血管疾病成为该人群死亡的最大原因。糖尿病患者患有加速的动脉粥样硬化，并且还表现出对心肌缺血的血管生成反应减弱。使用生长因子如血管内皮生长因子（VEGF）和成纤维细胞生长因子-2（FGF-2）的血管生成疗法已在许多动物模型中显示出改善冠状动脉血流和左心室功能障碍，对于患有终末期冠状动脉疾病（CAD）的糖尿病患者是特别有吸引力的治疗选择。然而，临床试验未能证明治疗性血管生成在晚期CAD患者中的疗效。尽管一些小鼠和体外研究已经指出了解释糖尿病缺乏血管生成反应的可能机制，但这些概念在大型动物研究中的验证和扩展是其在人类中应用的必要先决条件。本研究项目旨在研究糖尿病及其导致的内皮功能障碍对内源性和生长因子诱导的慢性心肌缺血临床前猪模型中心肌血管生成的影响。研究的重点将是侧支依赖性血流、血管密度和微血管功能的功能变化，以及体内血管生成过程改变所涉及的关键分子事件。将产生两种糖尿病模型：1）尤卡坦小型猪，使用链脲佐菌素（STZ）（一种杀死产生胰岛素的胰腺细胞的药物），将产生一种模拟I型糖尿病患者中存在的许多异常的模型，以及2）Ossabaw猪，喂食致动脉粥样硬化饮食，将产生类似于II型糖尿病的葡萄糖耐受不良和胰岛素抵抗。在这两种模型中，我们将通过建立慢性心肌缺血诱导内源性血管生成反应。我们建议确定：慢性心肌缺血的内源性功能性血管生成反应以及STZ诱导的糖尿病（目的1）和基因型/饮食诱导的葡萄糖耐受不良和胰岛素抵抗（目的2）中心肌血管生成相关分子途径。STZ诱导的糖尿病对生长因子诱导的血管周围FGF-2和VEGF治疗的功能性血管生成反应的影响以及涉及的分子途径将在目的3中研究。目的4将研究血糖控制（即维持血糖低于150 mg/dL）对STZ诱导的糖尿病慢性心肌缺血的内源性和生长因子诱导的功能性血管生成反应的影响。我们希望这些研究的结果将带来重要的洞察机制抑制慢性缺血诱导的内源性血管生成和反应的外源性因素在更多相关的糖尿病动物模型。

DESCRIPTION (provided by applicant): Over 35 million people in the United States are affected by diabetes and glucose intolerance. These individuals carry up to eight times the risk of cardiovascular events compared to non-diabetic individuals, making cardiovascular disease the largest cause of mortality in this population. Diabetic patients suffer from accelerated atherosclerosis and also exhibit a diminished angiogenic response to myocardial ischemia. Angiogenic therapy using growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2), which has been shown to improve coronary flow and left ventricular dysfunction in numerous animal models, is a particularly attractive therapeutic option for diabetic patients with end-stage coronary artery disease (CAD). However, clinical trials have failed to demonstrate the efficacy of therapeutic angiogenesis in patients with advanced CAD. Although some studies in mice and in vitro have pointed to possible mechanisms explaining the lack of angiogenesis response in diabetes, the validation and extension of these concepts in large animal studies is an essential prerequisite to their application in humans. This research project aims to study the effects of diabetes and resulting endothelial dysfunction on endogenous and growth factor induced myocardial angiogenesis in a well-established pre-clinical porcine model of chronic myocardial ischemia. The focus of the research will be on functional changes in collateral- dependent flow, vascular density, and microvascular function, as well as key molecular events involved in the altered angiogenic process in-vivo. Two models of diabetes will be produced: 1) Yucatan miniswine, using streptozotocin (STZ), (a drug that kills pancreatic cells producing insulin) will create a model that mimics many of the abnormalities present in type I diabetic patients, and 2) Ossabaw swine fed an atherogenic diet that will develop a glucose intolerance and insulin resistance similar to type II diabetes. In both models we will induce an endogenous angiogenic response by creating a chronic myocardial ischemia. We proposed to determine: The endogenous functional angiogenic response to chronic myocardial ischemia as well as on the molecular pathways involved in myocardial angiogenesis in STZ-induced diabetes (Aim 1) and in Genotypic / diet induced glucose intolerance and insulin resistance (Aim 2). The influence of STZ-induced diabetes on the growth factor induced functional angiogenic response to perivascular FGF-2 and VEGF therapy as well as the molecular pathways involved will be studied in Aim 3. Aim 4 will study the effect of glycemic control (i.e. maintenance of plasma glucose less than 150 mg/dL) on the endogenous and growth factor induced functional angiogenic response to chronic myocardial ischemia on STZ-induced diabetes. We hope that the results of these studies will bring important insights about the mechanisms inhibiting chronic ischemia induced endogenous angiogenesis and the response to exogenous factors in more relevant animal models of diabetes.