树突状细胞源外泌体miRNA-126对小鼠心肌梗死后血管新生的作用及机制研究

Angiogenesis is a key point of myocardial repair after myocardial infarction (MI), post-infarction myocardial angiogenesis is impaired by DC depletion, and myocardial remodeling is aggravated, but the mechanism remains unclear. We found that the expression of miRNA-126 was significantly increased both in DC and exosomes derived from DC (DEX) in preliminary study, there were researches showed that miRNA-126 can induce angiogenesis, so we hypothesis that DEX-miRNA-126 can promote cardiac angiogenesis by regulate cardiac microvascular endothelial cell (CMEC) after MI. In vitro, fluorescent labeling and confocal laser scanning microscope were used to observe the secretion of DEX and transfer of endogenous DEX between DC and CMEC firstly, then we investigate the effects of DEX-miRNA-126 on improving the function of migration and tube formation of CMEC, and luciferase assay was used to confirm the target gene of miRNA-126. In vivo, based on MI model of conditional DC knockout mice, we evaluate the relationship between the expression of DEX-miRNA-126 and cardiac angiogenesis, and study the positive effects on cardiac angiogenesis by inject DEX-miRNA-126 through tail vein. This project presented an innovative theory that DC can improve the cardiac remodeling after MI by secretion of DEX-miRNAs.

血管新生是心肌梗死（MI）后心肌修复的关键环节，树突状细胞（DC）敲除小鼠MI后心肌微血管（CMV）新生障碍，心肌重构加重。我们前期研究发现心肌细胞坏死液刺激DC后其分泌外泌体miRNA-126（DEX-miRNA-126）明显增高，而miRNA-126是CMV新生的重要调控因子。因此假设：MI后DC分泌DEX-miRNA-126并参与调控心肌微血管内皮细胞（CMEC）功能进而引起CMV新生。本项目拟采用荧光标记技术进一步证实DC分泌DEX-miRNA-126；体外研究DEX-miRNA-126对CMEC成管功能、迁移能力的作用和调控机制；通过条件性DC敲除小鼠MI模型并回输DEX-miRNA-126，在体确定DEX-miRNA-126引起CMV新生并改善心肌重构的作用。本项目提出了MI后DC分泌DEX-miRNAs参与CMV新生的新见解，为改善MI后心肌重构提供了新的干预靶点。

血管新生是心肌梗死（MI）后心肌修复的关键环节，树突状细胞（DC）敲除小鼠MI后心肌微血管（CMV）新生障碍，心肌重构恶化。本项目证实了树突状细胞DCs能分泌大量外泌体DEXs，体外实验发现DEXs能直接被CMECs摄取，并上调CMECs中VEGF的表达，增强CMECs的成管能力。通过基因芯片筛查并经qRT-PCR验证发现，一些与血管新生密切相关miRNAs的表达在MI-DEXs中显著增高，进一步研究发现miRNA-494-3p/146a mimic转入DEXs后可显著增强CMECs的成管作用。同时在体研究显示，MI小鼠模型在心梗部位肌注miRNA-494-3p/146a mimic-MI-DEXs能显著改善小鼠MI后的血管新生及改善心脏功能。另外，我们经尾静脉注射DEXs给小鼠后，发现MI-DEXs较对照组能更快更多的聚集在小鼠脾脏并能被CD4+ T淋巴细胞摄取及激活CD4+ T淋巴细胞，使小鼠MI部位血管新生显著增强，并改善了小鼠MI后的心功能。本项目通过免疫炎症机制，采用DCs分泌的DEXs作为媒介，为改善MI后心肌重构提供了新的干预靶点。