人脐带血间充质干细胞来源的外泌体经miR-181c改善早产仔鼠脑损伤的机制研究

TLR4 / Myd88 / NF-κB-related inflammatory signaling pathway plays an important role in the development and progression of brain injury in premature mice. Abnormal activation can induce the release of a large number of proinflammatory cytokines and lead to neuronal damage. We found that mesenchymal stem cell therapy significantly reduced the incidence of LPS-induced brain injury in premature mice. Since the miR-181c in exosomes derived from human umbilical cord blood mesenchymal stem cells(hUCMSCs) can down-regulate LPS-induced activation of TLR4 signaling pathway, we believe that miR-181c in the exosomes of hUCMSCs can inhibit microglias of premature mice producing proinflammatory cytokine by down-regulating TLR4 / Myd88 / NF-κB inflammation-related signaling pathways, and at last, reduce the damage to neurons. On the basis of pre-experimental study, the effects and mechanisms of the exosomes derived from hUCMSCs and the possible role of miR-181c from the exosomes on brain injury in premature mice were studied from cell, tissue and animal by using in vitro cell model and premature mouse model. This study is of great significance and research value for both the mechanism of preterm brain injury and the clinical application of stem cells in the future.

TLR4/Myd88/NF-κB炎症相关信号通路在早产小鼠脑损伤的发生发展中起重要调控作用，其异常活化可诱导小胶质细胞释放大量致炎因子进而导致仔鼠神经元损伤。我们预实验发现间充质干细胞治疗可显著降低LPS诱发的早产仔鼠脑损伤发生率。由于人脐血间充质干细胞（hUCMSCs）外泌体miR-181c可以下调LPS诱导的TLR4炎症信号通路活化，据此我们认为：hUCMSCs外泌体中miR-181c通过调节TLR4/Myd88/NF-κB炎症相关信号通路，也可抑制早产小鼠小胶质细胞致炎因子产生进而减轻对神经元的损伤。本课题在预实验研究的基础上，采用体外细胞模型及早产小鼠模型，从细胞、组织器官到动物，深入研究hUCMSCs来源的外泌体对早产仔鼠脑损伤的影响及机制及外泌体来源的miR-181c在其中的可能作用。这项研究无论对于早产脑损伤的机制研究还是未来干细胞的临床应用都具有重要意义和研究价值。

TLR4/Myd88/NF-κB炎症相关信号通路在早产小鼠脑损伤的发生发展中起重要调控作用，其异常活化可诱导小胶质细胞释放大量致炎因子进而导致仔鼠神经元损伤。本项目通过在体、离体及慢病毒干扰关键分子等多种技术阐明脐血间充质干细胞来源的外泌体(hUCMSCs-exo)经miR-181c通过TLR4信号通路对宫内感染早产仔鼠模型学习记忆能力的保护作用及机制。我们发现，hUCMSCs-exo预处理后，宫内感染早产仔鼠的学习记忆能力、神经运动功能、海马组织形态等均得到明显改善；这可能与孕鼠体内炎性反应被抑制有关。细胞实验中，hUCMSCs-exo促进LPS刺激的小胶质细胞M2极化，抑制M1极化，降低小胶质细胞引发的炎性损伤。上述作用与其经miR-181c调控小胶质细胞TLR4通路表达，进而减轻LPS刺激后细胞的炎症反应、改变炎性因子表达有关。上述研究结果为干细胞围孕期的应用提供了理论基础，为早产脑损伤的防治提供了新的思路。