心肌缺血损伤及保护的新机制-线粒体miRNAs的作用

Myocardial ischemia/reperfusion injury(MI/RI) remains an important issue in the clinical settings. Remote ischemic preconditioning(RIPC) is an endogenous cardioprotective strategy which has been most widely translational used in the clinical practice. Mitochondria not only acts as the final barrier of MI/RI, but also has been recognized as the end-effector in cardioprotection. Previous identified microRNAs(miR) associated with the myocardial ischemia and/or cardioprotection all comes from the total cardiomyocytes. Recently, miR has also been found to translocate into the mitochondria, regulate the mitochondrial function, and even participate in the process of apoptosis. In the previous work, we have extracted the miR in the cardiac mitochondria, and found that both MI/RI and RIPC could affect its level. Based on these evidence, we hypotheses that mitochondrial miRs may be a novel underlying mechanism in the ischemic injury or the protection of myocardium. This work will use the comparative mitochondrial microRNome to screen the key miRs of the mitochondria in an isolated rat heart model during different ischemic stimulus or RIPC, and confirm the function in the isolated cardiomyocytes and cardiac mitochondria. Our aim is to establish several key mitochondrial miRs associated with the myocardial ischemia or cardioprotection. To our knowledge, this work is the first one to explore the novel role of mitochondrial miRs in myocardial ischemia and cardioprotection in the Ex Vivo heart level, In Vitro cardiomyocyte level, and In Vitro myocardial mitochondrion level. Our work will offer a distinct viewsight, a novel target, and a new theoretical basis for the preventive approach of MI/RI.

心肌缺血/再灌注损伤(MI/RI)仍然是临床中的重要问题。远隔缺血预处理（RIPC）是目前转化应用最为广泛的内源性心肌保护措施。线粒体作为MI/RI的最后屏障，亦是心肌保护的最终效应器。既往发现的与心肌缺血损伤及保护有关的微小RNA(miR)均来源于整体细胞，而最新研究发现线粒体内也存在miR，可调控其呼吸功能，甚至参与凋亡。我们已在心肌线粒体中提取出miR，并发现MI/RI和RIPC均可影响其水平。据此，我们提出“线粒体miR是介导心肌缺血损伤及保护的新机制”的假说。本课题拟采用比较线粒体miR组学，从离体灌流心脏筛选不同缺血时间及RIPC的关键线粒体miR，同时在心肌细胞和线粒体模型中进行功能验证，拟寻找到与心肌缺血损伤及保护有关的线粒体miR。本课题首次在器官、细胞及线粒体三个水平探索线粒体miR在心肌缺血损伤及保护中的作用，为MI/RI的防治提供新的思路、、新的靶点和新的理论依据。

本课题组3年来严格按照计划任务书要求不懈努力，围绕“心肌缺血损伤保护”这一主要课题，完成了部分预定任务，取得了一些科研成果，并注意瞄准国际前沿进行一定的探索。首先，观察到远隔缺血预处理(remote ischemic preconditioning, RIPC)发挥心肌保护作用可能与缺血后心肌线粒体内ATP合成量增加有关，目前所有线粒体标本均已-80℃冻存，为下一步关键miRNA的筛选与验证作准备。然后，探索了老龄对七氟醚后处理心肌保护时缺血相关miRNA-1/21的影响，为下一步研究老龄削弱无创性处理性心肌保护的miRNA相关的新机制打下一定的基础。其次，发现钙调蛋白1型钠钙交换体失活可能是七氟醚后处理优于单次延迟相远隔缺血预处理心肌保护作用的潜在新机制，为下一步探索作好铺垫。本课题组有关无创性心肌保护措施尤其是远隔缺血预处理的系列研究填补了以前相关工作的空白，并注重以新机制为导向，较大地丰富了此类研究的内容和意义。. 本课题组的工作以系列文章发表在国外专业杂志上，共发表文章5篇（完全为本项目独立完成的文章），其中SCI收录5篇（IF>2, 4篇；IF<2，1篇；主要资助 4篇，部分资助 1篇）。英文壁报1篇，英文口头发言1次。本项目组平均投入产出比值为每十万元专项资助完成SCI 2.2篇，产出的成本较高。