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（MI），伴有功能性心肌的不可逆丧失，除非迅速进行再灌注治疗。许多患者不存在或不适合于迅速再灌注，并且在这个大的患者群体中，需要新的治疗方法。在动物模型和患者中对MI后基于细胞的治疗的初步研究提供了令人鼓舞的结果，但理想的供体细胞群尚未确定。初步数据显示，MI后移植未分化的小鼠胚胎干细胞（ESC）导致小鼠MI模型中的心肌修复;然而，主要的机制问题和障碍仍然存在，例如肿瘤形成的风险。我们假设来源于中胚层或心脏谱系的ESC的细胞制剂可以修复心肌，且肿瘤发生的风险最小。其次，我们假设移植ESC衍生细胞的最佳益处是通过旁分泌效应短期减少梗死面积和在缺乏显著融合的情况下移植细胞增殖和分化导致心肌长期再生的结果。本研究的长期目标是通过提供有效性和安全性的基本临床前研究，开发使用ESC修复MI后心肌的细胞疗法。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道分子鉴定和表征对于心肌修复最佳的ESC衍生的供体细胞，同时具有最小的肿瘤发生风险，以分离中胚层祖细胞和胚胎心室肌细胞; 2）开发策略以调节供体细胞，以改善在采用体外缺血和再灌注模型的MI后心脏典型的缺血和氧化应激环境中的存活;和3）确定心肌梗死后ESC和衍生物移植的效果，评估短期（梗死面积、细胞存活、细胞增殖）和长期（通过超声心动图和组织学的LV结构和功能、用微CT和病理学的肿瘤监测、通过共免疫标记和Cre/lox供体/受体技术的细胞命运/融合、以及使用细胞电生理学的再生肌细胞表型）结果。总的来说，这些研究将为MI后的细胞治疗提供新的见解，并使使用人类ESC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.