内皮细胞源性外泌体携带microRNAs在血管内皮损伤中的保护性调节作用研究

Atherosclerosis is initiated and propagated by a continuous damage of the vascular endothelium leading to endothelial activation. Endothelial cells (ECs) activation triggers the release of endothelial cells-derived exosomes which are important carriers of circulating microRNAs and play essential roles in cell-cell crosstalk. Our previous studies in unstable coronary heart disease showed that the differentially expressed microRNAs in plasma of unstable coronary heart disease were closely associated with ECs activation. However, it is not very clear whether endothelial exosomes, released from injured ECs, could influence ECs repair by transferring microRNAs to target ECs. The present study aims to investigate the following contents: (1) endothelial exosomes regulate the migration and proliferation of recipient ECs, (2) the mechanism underlies endothelial exosomes in regulating the biological activities of recipient ECs by transferring microRNAs into them, (3) endothelial exosomes influence reendothelialization of injured vascular endothelium in C57BL/6 mice. The ultimate purpose of this study is to determine the atheroprotective microRNAs mediated by exosomes in recipient ECs and their target genes. This project will present new clues for early prevention and treatment of atherosclerosis.

血管内皮损伤致内皮细胞激活是动脉粥样硬化的始动因素。细胞激活后以外泌体等形式释放的microRNAs可进入其他细胞，发挥细胞间的信息通讯作用。我们既往证实内皮细胞激活与不稳定冠心病中循环microRNAs差异表达谱密切相关。但损伤内皮激活后能否分泌载有microRNAs的外泌体，在内皮细胞间发挥保护性调节作用，目前尚不清楚。因此，本研究拟从动脉粥样硬化早期阶段——内皮损伤这一病理改变入手，分别在细胞和动物水平探讨血管内皮细胞源性外泌体（1）对受体内皮细胞的生物学调节作用：观察细胞增殖和迁移，（2）调控受体内皮细胞生物学效应的机制：筛选差异表达microRNAs、预测并验证其靶基因及功能，（3）在小鼠损伤动脉再内皮化中的作用：观察损伤股动脉的内皮再生。通过上述研究，确定在内皮损伤修复过程中，具有保护作用的外泌体内microRNAs及其靶基因，最终为动脉粥样硬化早期防治提供新线索。

血管内皮损伤致内皮细胞激活，随后细胞分泌具有生物活性的外泌体。外泌体进入其他细胞后，对该细胞产生生物学调控作用。microRNAs是细胞增殖、迁移、血管新生等生物学过程的重要调控分子。本研究拟观察内皮细胞激活后释放的外泌体，是否在microRNAs介导下对损伤内皮产生保护性作用。主要研究结果如下：（1）与正常培养条件下内皮细胞释放的外泌体（对照组外泌体，Exo-Con）相比，H2O2刺激组细胞释放的外泌体（实验组外泌体，Exo-H2O2）可以促进内皮细胞增殖、迁移和血管新生；（2）Exo-H2O2可抑制内皮细胞内miR-92a-3p的表达，过表达miR-92a-3p可阻断Exo-H2O2的上述生物学效应；（3）单纯抑制内皮细胞miR-92a-3p的表达，可在体抑制血管形成；（4）具有促血管生成作用的组织因子是miR-92a-3p的靶基因。本研究证实miR-92a-3p下调，介导了Exo-H2O2的促血管内皮细胞增殖、迁移、和血管新生作用，并且组织因子可能参与了miR-92a-3p的这一生物学调控作用。该研究揭示了外泌体介导的内皮细胞间的信号传递作用，丰富了外泌体在血管内皮损伤后的保护性调控作用机制，为损伤内皮的修复提供了新的途径和理论依据。