Nrf2基因修饰MSC增强脂肪肝供肝肝移植损伤保护及相关microRNA调控机制

Fatty livers are more sensitive to ischemia reperfusion injury and immune injury than normal livers. Attenuation of ischemia reperfusion injury and immune injury and increasing utilization rate of donor from fatty liver is an important task in the field of liver transplantation. Mesenchymal stem cells represent a promising cell source for tissue repair and gene delivery. However, transplanted mesenchymal stem cells survive for a rather short time after in vivo implantation. Repeated infusions of mesenchymal stem cells are more effective in improving efficacy compared with single infusion. Our previous study showed that mesenchymal stem cells attenuate ischemia reperfusion injury of fatty liver in rats,and have an unique immunomodulatory property. Both of these characteristics are related to the regulatory function of microRNA. Nrf2, as one of the most important cellular protective transcription factors, demonstrates the protective effects on the liver injury. In this study, we investigate that whether mesenchymal stem cells overexpressing Nrf2 can reduce oxidative stress-induced apoptosis and cytotoxicity, prolong its survival time in vivo, and enhance their function of attenuating ischemia reperfusion injury and immune injury of fatty liver graft after liver transplantation in rats. We also investigate the regulation mechanisms of microRNA related to signaling passway of Keap1-Nrf2-ARE on mesenchymal stem cells-mediated protection from ischemia reperfusion injury and immune injury. The results of the study will not only provide a new theoretical basis for mesenchymal stem cells for treatment of ischemia reperfusion injury and immune injury in liver transplantation, but also provide a new way for attenuating hepatic ischemia reperfusion injury and immune injury after liver transplantation, and increase the successful rate of liver transplantation with fatty liver graft.

脂肪肝对缺血再灌注损伤(IRI)和免疫损伤更敏感。减轻IRI和免疫损伤、提高脂肪肝供肝利用率是肝移植领域的重要课题。间充质干细胞(MSC)通过组织修复、免疫调节、基因治疗等发挥损伤保护作用，但MSC在体内作用时间短影响其疗效。我们已发现①细胞防御系统中最重要的转录因子Nrf2明显减轻肝脏损伤；②MSC多途径发挥免疫调节作用；③MSC减轻脂肪肝IRI并与Nrf2上调有关；④前述研究中microRNA参与IRI及免疫调节。本课题建立大鼠脂肪肝供肝肝移植模型(模拟肝移植临床实际问题，术后早期同时发生IRI和免疫损伤)，以Nrf2为切入点，研究携带Nrf2的MSC是否延长其体内作用时间、增强其减轻IRI和免疫损伤作用，并探讨相关microRNA在MSC发挥损伤保护作用中的调控机制，旨在阐明MSC对脂肪肝供肝肝移植损伤保护作用中Nrf2的关键作用及内在机制，为肝移植IRI和免疫损伤提供新的治疗方法。

脂肪肝对缺血再灌注损伤(IRI)和免疫损伤更敏感。前期研究中我们已发现①细胞防御系统中最重要的转录因子Nrf2明显减轻肝脏损伤；②MSC 多途径发挥免疫调节作用；③MSC 减轻脂肪肝 IRI 并与Nrf2上调有关。本课题在上述工作基础上，构建了稳定过表达Nrf2基因的人间充质干细胞；观察了氧化应激下Nrf2-MSC的凋亡和分化能力；发现Nrf2具有调控Hif1α的作用。稳定建立了小鼠脂肪肝缺血再灌注损伤模型，发现Nrf2-MSC能明显减轻脂肪肝小鼠肝脏缺血再灌注损伤，其机制与抗氧化应激有关，并分析了多种microRNA的调控作用。上述研究部分阐明了MSC对脂肪肝缺血再灌注损伤保护作用中 Nrf2 的关键作用及内在机制，为肝脏缺血再灌注损伤提供新的治疗方法，Nrf2-MSC可作为一种重要的治疗方法预防和治疗肝脏缺血再灌注损伤。