Surgical Intramyocardial Angiogenesis in a Swine Model

血管新生是治疗冠状动脉疾病(CAD)的一种很有前途的新治疗方法。然而，尽管我们的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少量的客观益处。终末期冠心病患者代表了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，导致内皮物质的异常产生和反应。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发挥作用的，所以在终末期冠心病患者中观察到的作用失败可能与这些内皮源性物质的刺激释放不足有关。本研究旨在明确血管内皮细胞功能在外源性生长因子治疗效应中的作用，以及在心肌缺血后内源性血管生成反应中的作用。为此，将使用高胆固醇血症猪模型，重建与人类冠心病患者相似的心肌微循环变化。将建立几个研究小组，包括内皮正常、功能障碍或经药物治疗的动物，其中将进行慢性心肌缺血的外科诱导和植入缓释生长因子设备(成纤维细胞生长因子-2、血管内皮生长因子或安慰剂)。在每个研究组中，将在微血管反应性研究的基础上体外评估内皮反应，并将使用同位素标记的心肌灌注微球分析、声学显微测量、免疫细胞化学和实时PCR分析等工具，在功能、微血管、组织和分子水平上定量确定血管生成反应。通过阐明内皮细胞和内皮调节剂在功能性血管生成反应中的作用，本研究的发现将使人们对治疗性血管生成有更全面的了解，并可能使这一模式的发展成为一种安全、有效和有吸引力的治疗冠心病的选择。

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.