心肌细胞源性BDNF对正常与缺血心肌作用机制及衰老对其影响的研究

Understanding functional role and mechanism of protective and survival factors which are derived from cardiac myocytes is one of key issues for regeneration of infarcted myocardium. In our prior report, we demonstrated that cardiac microvascular endothelial cells-derived BDNF（Brain derived neurotrophic factor） is able to promote angiogenesis of myocardium and plays benefit effectors in the regeneration of myocardial infarction (MI). Recently we further develop a line of cardiac myocyte conditional knockout BDNF mice. It provides us further prosibility to document functional roles of cardiac myocytes derived BDNF in cardiac physiology and phathology of ischemic myocytes. The present study is therefore designed to study: 1) the roles of cardiac myocyte conditional knockout BDNF in integrity of structure and function of heart, survival rate and the the effects of aging included in this precess in order to reveal the related mechanisms which are involved; 2) MI in young and old cardiac myocyte conditional knockout BDNF mice in order to document the role and the mechanism of cardiac myocytes derived BDNF in MI, and aging effects included in this process; 3) the targets which are identified in item-1 and -2, and the suitable window and dosage of BDNF therapy for MI and the related mechanism. The results of this study will provide novel mechanism, therapeutic targets and therapy for: ①maintaining the physiological function of heart; ②regeneration of MI; ③delay heart aging.

阐明能促进心肌细胞存活与再生的心脏内源性因子的作用机理，是再生梗死心肌的关键。在揭示：心脏微血管内皮细胞源性BDNF(脑源性神经营养因子)能促进心肌血管新生而有利于梗死心肌再生的基础上，我们又构建了心肌细胞条件敲除BDNF小鼠，使阐明心肌细胞源性BDNF对心脏生理及缺血性心肌病理的调控机理成为可能。本项目将：1）对心肌条件性敲除BDNF对心脏形态和功能，存活率与野生型的异同进行研究，以揭示心肌细胞源性BDNF在心脏结构与功能、个体存活的调控角色，及衰老对其的影响；2）对年青和年老心肌条件性敲除BDNF小鼠的心肌缺血梗死进行研究，以揭示心肌细胞源性BDNF对其的调控功能及机理，及衰老对相应功能的影响；3）依据研究内容1和2甄别的靶点，对BDNF能有效再生梗死心肌的最佳时间窗与用量，及实现疗效的机理进行研究。为：①维持心脏正常功能；②再生缺血梗死心肌；③延缓心脏衰老带来新的机理、靶点和疗法。

心肌细胞源性的脑源性神经营养因子（BDNF）对心脏生理与病理的调控功能尚不清楚。本研究构建了从心肌细胞发育表达MYH6起即敲除心肌细胞源性BDNF小鼠并进行系列研究，揭示了：1）在心肌细胞发育阶段行心肌细胞特异性敲除BDNF的小鼠能发育、生长及传代，但成年后，1年生存率显著降低，大部分约在1年左右死亡；2）与野生型相比，心肌细胞特异性敲除BDNF小鼠，在成年（约3月龄）出现：体能指标显著下降，心功能障碍（左室射血分数和缩短分数显著下降，且左室收缩末期内径、舒张末期内径、收缩末期容积和舒张末期容积显著升高）和躯体水肿的心衰表型，心脏出现向心性心肌肥厚，心肌细胞及心肌细胞核面积增大，心肌细胞死亡，心肌层出现退行性与炎症性改变（心肌细胞变性，炎症细胞浸润，间质纤维化增加，线粒体吞噬和线粒体肿胀）和左心耳血栓, 心肌层心衰标记物：心房利钠肽和脑利钠肽的表达均显著升高，血清心衰指数：NT-pro-BNP、BNP和galectin-3水平显著升高，血清BDNF、胰岛素水平显著升高；3）心肌细胞特异性敲除BDNF心脏发生心肌梗死时，心梗心脏的梗死面积及心功能显著差于野生型心脏，呈修复与再生能力下降；4）转录组与血清蛋白组结合权威生物通路IPA系统分析，揭示了：①心肌细胞特异性敲除BDNF导致心肌细胞死亡、心肌退行性病理、心脏炎症和ROS激活、体重增加和代谢紊乱的调控通路和基因互作网络；②心肌细胞条件敲除BDNF，导致心肌细胞结构蛋白大量入血，且机体的糖酵解、肌动蛋白细胞骨架调控、Integrin信号、Rho介导的肌动蛋白调控、Apelin心肌细胞信号通路、心肌肥大信号通路、白细胞侵入信号通路等被激活。本研究揭示了：心肌细胞源性BDNF在维持心脏结构和功能的完整，抑制心肌细胞结构与功能退行性改变，及损伤心脏的修复与再生具有不可替代的作用。已发表标注项目资助号SCI论文5篇（1篇将投稿），培养研究生3人。