Surgical Intramyocardial Angiogenesis in a Model

血管生成是治疗冠状动脉疾病（CAD）的一种有前景的新治疗方式。然而，尽管我们实验室和其他实验室的动物研究取得了令人印象深刻的结果，但血管生成疗法在人类中的初步临床应用仅产生了适度的客观益处。终末期CAD患者是目前血管生成治疗的目标人群，几乎所有患者都有晚期内皮功能障碍，导致内皮物质产生和反应异常。由于血管生成生长因子在很大程度上是通过激活酪氨酸激酶受体释放内皮源性一氧化氮来起作用的，因此在终末期CAD患者中观察到的效果失败可能与这些内皮源性物质的刺激释放不足有关。本研究拟明确内皮功能在外源性生长因子治疗效果和内源性心肌缺血血管生成反应中的作用。为此，将使用高胆固醇血症猪模型来重建与冠心病患者相似的心肌微循环变化。将建立几个研究组，包括内皮正常、功能失调或经药物处理的动物，其中将进行慢性心肌缺血手术诱导和植入缓释生长因子装置（FGF-2、VEGF或安慰剂）。在每个研究组中，内皮反应将在体外微血管反应性研究中进行评估，血管生成反应将在功能、微血管、组织学和分子水平上定量测定，使用的工具包括同位素标记的心肌灌注微球测定、声速测定法、免疫细胞化学和实时PCR分析。通过阐明内皮和内皮调节剂在功能性血管生成反应中的作用，本研究的发现将导致对治疗性血管生成的更全面的理解，并可能使这种治疗方式朝着安全、有效和有吸引力的冠心病治疗选择发展。

Angiogenesis is a promising new therapeutic modality for the treatment of coronary artery disease (CAD). However, despite impressive results of animal studies from our laboratory as well as others, preliminary clinical use of angiogenic therapy in humans has only resulted in modest if any objective benefit. Patients with end-stage CAD, who represent the population currently targeted by angiogenic therapy, virtually all have advanced endothelial dysfunction that results in abnormal production and response to endothelial substances. Since angiogenic growth factors operate in large part through the release of endothelial-derived nitric oxide via the activation of tyrosine kinase receptors, the observed failure of effect in patients with end-stage CAD may relate to a deficiency in the stimulated release of these endothelial-derived substances. This research proposes to define the role of endothelial function on the effects of exogenous growth factor therapy and on the endogenous angiogenic response to myocardial ischemia. To this end, a hypercholesterolemic porcine model will be used that recreates myocardial microcirculatory changes similar to those encountered in humans with CAD. Several study groups that include animals with normal, dysfunctional, or pharmacologically- treated endothelium will be created, in which surgical induction of chronic myocardial ischemia and implantation of sustained- release growth factor devices (FGF-2, VEGF, or placebo) will be performed. In each study group, endothelial responses will be assessed in vitro on microvascular reactivity studies, and the angiogenic response will be quantitatively determined at the functional, microvascular, histological, and molecular levels, using tools such as isotope-labeled microsphere assays of myocardial perfusion, sonomicrometry, immunocytochemistry and real time PCR analysis. By clarifying the role of the endothelium and endothelial-modulating agents in the functional angiogenic response, the findings from this research will lead to a more complete understanding of therapeutic angiogenesis, and may allow for the development of this modality towards a safe, effective, and attractive option for the treatment of CAD.