Embryonic Stem Cell-based Therapies for Myocardial Infarction

描述(由申请人提供)：急性冠状动脉血栓形成导致心肌梗死(Ml)，并导致功能心肌不可逆转的丧失，除非迅速开始再灌注治疗。许多患者不存在或不能迅速再通，在这个庞大的患者群体中，需要新的治疗方法。在动物模型和患者中进行的心肌梗死后基于细胞的治疗的初步研究已经提供了令人鼓舞的结果，但理想的供体细胞群体尚未确定。初步数据显示，在心肌梗死后移植未分化的小鼠胚胎干细胞(ESCs)，在小鼠ML模型中导致了心肌修复；然而，主要的机制问题和障碍仍然存在，如肿瘤形成的风险。我们假设，来源于胚胎干细胞的细胞制剂致力于中胚层或心脏谱系，可以在最小的肿瘤发生风险下修复心肌。其次，我们假设移植的胚胎干细胞来源的细胞的最佳益处是通过旁分泌效应在短期内缩小梗塞面积，以及在没有明显融合的情况下移植细胞的增殖和分化导致心肌的长期再生。这项研究的长期目标是开发使用胚胎干细胞的细胞疗法，通过提供必要的临床前有效性和安全性研究来修复ML后的心肌。我们建议：1)使用细胞表面标志物和遗传细胞类型特异性报告基因来分离中胚层前体细胞和胚胎心肌细胞，以确定和表征最适合心肌修复的ESC来源的供体细胞，以最大限度地降低肿瘤发生的风险；2)利用体外缺血和再灌注模型，制定策略以改善供体细胞在心肌梗死后典型的缺血和氧化应激背景下的生存；3)确定胚胎干细胞及其衍生物在心肌梗死后移植的效果，评估短期(梗死面积、细胞存活、细胞增殖)和长期(超声心动图和组织学检测左室结构和功能，显微CT和病理监测肿瘤，联合免疫标记和Cre/lox供体/受体技术检测细胞命运/融合，以及细胞电生理学检测再生心肌细胞表型)的结果。总体而言，这些研究将为心肌梗死后基于细胞的治疗提供新的见解，并使使用人类胚胎干细胞的方法更接近临床应用。

DESCRIPTION (provided by applicant): Acute coronary thrombosis results in myocardial infarction (Ml) with irreversible loss of functional myocardium unless reperfusion therapy is rapidly instituted. Many patients do not present or are not amenable to prompt reperfusion, and in this large patient population new therapeutic approaches are needed. Initial studies of cell-based therapies post-MI in animal models and in patients have provided encouraging results, but the ideal donor cell population has not been determined. Preliminary data show that transplantation of undifferentiated mouse embryonic stem cells (ESCs) post-MI, resulted in myocardial repair in a mouse Ml model; however, major mechanistic questions and roadblocks remain such as the risk of tumor formation. We hypothesize that cell preparations derived from ESCs that are committed to mesodermal or cardiac lineages can repair the myocardium with minimal risk of tumorigenesis. Secondly, we hypothesize that the optimal benefit from transplanted ESC-derived cells is the result of a short-term reduction in infarct size via paracrine effects and long-term regeneration of myocardium resulting from the proliferation and differentiation of transplanted cells in the absence of significant fusion. The long-term goal of this research is to develop cellular therapies using ESCs to repair the myocardium following Ml by providing essential preclinical studies of efficacy and safety. We propose to: 1) identify and characterize ESC-derived donor cells optimal for myocardial repair with minimal risk of tumorigenesis using cell surface markers and genetic cell-type specific reporters to isolate mesodermal progenitor cells and embryonic ventricular myocytes; 2) develop strategies to condition donor cells for improved survival in the setting of ischemic and oxidative stress typical of the post-MI heart employing in vitro models of ischemia and reperfusion; and 3) determine the effect of transplantation of ESCs and derivatives post-MI evaluating both short-term (infarct size, cell survival, cell proliferation) and long-term (LV structure and function by echocardiography and histology, tumor surveillance with microCT and pathology, cell fate/fusion by co- immunolabeling and Cre/lox donor/recipient techniques, and regenerated myocytes phenotype using cellular electrophysiology) outcomes. Overall, these studies will provide new insights into cell-based therapies in the post-MI setting and bring approaches using human ESCs closer to clinical application.