ANGⅡ/AT1/SMAD/CX43通路在心肌干细胞提高心梗大鼠心电生理学稳定性和室颤阈值的作用机制研究

In our previous study, we have found that cardiac stem cell (CSC) transplantation could significantly improve the stability of cardiac electrophysiology and ventricular fibrillation threshold in rats with myocardial infarction(MI), but the exact mechanism is still unclear (Crit Care Med, 2011). Both ANG-Ⅱ/AT-1/SMAD and CX43 have been revealed to be strongly related with cardiac electrophysiology and ventricular fibrillation threshold, and our preliminary studies have also found that ACEI significantly improved stability of cardiac electrophysiology and ventricular fibrillation threshold. Therefore, the present project intends to explore this potential mechanism by studies as follows: 1.Arrhythmias will be detected before and after CSC transplantation into infarct rats with DSI physiology signals system. 2.ANG-Ⅱactivated after MI can significantly influence malignant reconstruction of CX43 through the ANG-Ⅱ/AT-1/SMAD pathway. 3.The expression and regulation of CX43 and ANG-Ⅱ/AT-1/SMAD pathway after CSC transplantation following MI will be observed in vivo and the relevance of them will be studied. 4.The molecular mechanisms of how CSCs regulate CX43 via ANG-Ⅱmodulation will be verified in vitro. The results will help to better understand the antiarrhythmic mechanisms of CSCs, which will provide a theoretical basis for the future treatment of arrhythmias following MI and cardiovascular diseases.

我们前期研究发现心肌干细胞（CSCs）移植治疗心肌梗死（MI）大鼠能够显著改善心电生理学稳定性和提高室颤阈值，但具体机制仍然未明（Crit Care Med，2011）。鉴于ANG-Ⅱ/AT-1/SMAD及CX43与心电生理学稳定性和室颤阈值密切相关，且我们前期研究发现ACEI能显著改进心电生理学稳定性和提高室颤阈值。因此，本项目拟：1.植入DSI生理信号系统，观察MI大鼠在CSCs移植前后心律失常出现情况。2.研究MI后ANG-Ⅱ激活能经由ANG-Ⅱ/AT-1/SMAD显著影响CX43不良重构。3.在体观察CSCs移植治疗MI后CX43表达情况及其调节CX43的ANG-Ⅱ/AT-1/SMAD分子通道表达情况并研究其相关性。4.体外验证CSCs干预 ANG-Ⅱ调节CX43的具体分子机制。研究结果将有助于更好了解CSCs抗心律失常的作用机制，从而为CSCs治疗心血管疾病提供理论基础成果。

背景：课题组前期研究证实心肌干细胞（CSCs）移植能有效改善心肌梗死大鼠的心电生理稳定性和室颤阈值，但具体的调控机制和通路不明。.主要研究内容：在原有CSCs移植治疗大鼠心肌梗死后心电生理学稳定性改善和室颤阈值提高的前提下，探讨CSCs治疗后，心肌梗死大鼠在自然状态下，其心律失常发生情况；以及心肌梗死大鼠心肌组织心电生理学稳定性恶化及室颤阈值的下降是ANG-Ⅱ过表达所导致的缝隙连接蛋白43（CX43）表达下降引起；同时筛选与CX43表达相关的ANG-Ⅱ/AT-1/SMAD/CX43通路各因子，验证CSCs移植治疗改善CX43重构从而改善电生理学稳定性和提高室颤阈值是否与ANG-Ⅱ及其相关的下游SMAD分子通道有关。.重要结果：心肌梗死大鼠心肌组织心电生理学稳定性恶化及室颤阈值的下降由ANG-Ⅱ过表达所导致的CX43表达下降引起，心肌干细胞移植治疗后，CX43在心肌干细胞组梗死区、梗死边缘区、非梗死区的表达明显增加(P < 0.05)；无论是治疗后2周还是6周，与PBS 组相比，心肌干细胞组ANG Ⅱ血浆和左心室各区域的表达明显减少(P < 0.05)；；心肌干细胞治疗后与PBS对照组相比左心室心肌组织不同区域AT1R、转化生长因子-β1（TGF-β1）、SMAD2、SMAD3 表达下降(P < 0.05)；，而AT2R和SMAD7 表达增加(P < 0.05)；以上结果表明，心肌干细胞移植改善心肌梗死大鼠的心电生理学稳定性和室颤阈值的机制可能与调控 ANG Ⅱ/AT1R/ TGF-β1/SMAD/CX43 通路，导致CX43 表达增加密切相关。.科学意义：在分子水平上阐述了CSCs移植改善心梗后心肌细胞的电生理学特性及提高室颤阈值的具体机制，从而对CSCs治疗心肌梗死后心律失常的确切的分子机制有了新的认识，并进一步推进了CSCs治疗心血管疾病的临床应用进程。