MSC通过线粒体转运减轻肝脏缺血再灌注损伤的机制研究

Hepatic ischemia reperfusion injury (HIRI) is an inevitable pathological process during liver transplantation or other kinds of hepatic surgeries and will retard the full recovery of liver function. There is a direct correlation between the severity of HIRI and long-term survival of liver grafts. Therefore, it is of great significance to delineate the underlying mechanism of HIRI and develop novel strategy to reduce HIRI. Our previous study found that mesenchymal stem cells (MSC) could alleviate HIRI, partly owing to its paracrine effects. Meanwhile, we observed that mitochondria transfered from MSCs to injured hepatocytes. As it is accepted that excessive oxygen free radicals originate from mitochondria and injured mitochondria is regarded as a trigger of the following HIRI, we hypothesize that mitochondria transfer may be another important pathway accounting for the protective effects of MSC during HIRI. The aim of our present research is trying to explore the unraveled mechanisms in this process. The cell-cell co-culture system will be used to mimic HIRI in vitro and observe mitochondria transfer from MSCs to hepatocytes and liver sinusoidal endothelial cells (LSEC), which will be further confirmed in a model of HIRI in rats. We will also try to figure out the possible transfer manners, such as tunneling nanotubes (TNTs) and/or microvesicles, which will be adopted by MSCs to deliver normal mitochondria to injured hepatocytes/LSECs. Furthermore, we will clarify the role of Nestin in mitochondria function maintenance and transfer regulation based on our former findings. This research will not only illuminate novel mechanisms of how MSCs ameliorate HIRI from a Mitochondria-Centric perspective, but also provide a new theoretical basis for their clinical application in the near future.

探究减轻肝脏缺血再灌注损伤（Hepatic ischemia reperfusion injury ,HIRI）新策略有助于肝外科术后的肝功能恢复。课题组前期发现间充质干细胞（MSC）可有效减轻HIRI，并证实旁分泌作用是其作用机制之一（J Sur Res, 2012）。进一步研究发现MSC与损伤肝细胞之间存在线粒体转运，提示健康线粒体调配可能是其另一重要作用机制。故本研究从线粒体转运入手，拟通过模拟HIRI的体内外实验，来进一步验明确：线粒体转运在MSC减轻HIRI中的作用、可能的转运方式（包括隧道纳米管、微囊泡等）和以Nestin为代表的细胞骨架在线粒体功能维护及转运过程中的调控机理，进而探究通过基因修饰等方式增强线粒体转运提高MSC疗效的可行性。本研究的顺利实施不但有助于深入探讨MSC减轻HIRI的作用新机制，也为研发基于MSC减轻HIRI的新策略提供理论基础和指导。

肝脏缺血再灌注损伤（hepatic ischemia reperfusion injury，HIRI）是指肝脏缺血再恢复血流灌注后，肝细胞功能代谢障碍及组织结构反而进一步加重的现象，是肝移植手术和其它肝胆外科手术中不可避免的病理生理过程。有效减轻肝脏缺血再灌注损伤能显著促进肝外科术后的肝功能恢复。课题组前期发现间充质干细胞（MSC）可通过旁分泌作用有效减轻HIRI。但具体机制尚待进一步明确。本项目从线粒体转运、自噬入手，通过模拟HIRI的体内外实验，明确了线粒体转运、线粒体自噬在MSC减轻HIRI中的作用，发现MSC在体内和体外均能通过降低mtROS积累、促进线粒体自噬等途径，促进PINK/PARKIN的表达和激活AMPKα通路来减轻肝细胞的凋亡。本研究的实施为探讨MSC减轻HIRI的作用机制提供了新的补充，为研发基于MSC减轻HIRI的新策略提供了理论依据。

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