肝缺血再灌注联合肝切损伤中MSC通过细胞间直接连接促进肝修复再生机制的纳米分子影像研究

Ischemia reperfusion injury (IRI) is inevitable during LTx and liver resectionnd will retard the full recovery of liver function.Therefore, it is of great significance to delineate the underlying mechanism of HIRI and develop novel strategy to reduce HIRI and regenerate liver. Our previous study found that mesenchymal stem cells (MSC) could alleviate IRI and rescuing liver, partly owing to its paracrine effects. Meanwhile, we bserved that cell-to-cell connections from MSCs to injured hepatocytes. We hypothesize that cell-to-cell connections may be another important pathway accounting for the protective and promoting regeneration effects of MSC during IRI. The study investigated the effect of MSC reducing hepatic hepatic ischemia reperfusion and accelerating liver regeneration in a combined hepatic IRI and partial hepatectomy model monitoring by Using in vivo visualization technique.The aim of our present research is trying to explore the unraveled mechanisms in this process. We will also try to figure out the possible connections manners, such as tunneling nanotubes (TNTs), and/or microvesicles, and/or cell fusion,which will be adopted by MSCs to accelerate liver regeneration. Furthermore, we will clarify in vivo the distribution and metabolism of MSCs related to liver regeneration . This research will not only illuminate novel mechanisms of how MSCs ameliorate HIRI and regenerate liver from cell-to-cell connections perspective, but also provide a new theoretical basis for their clinical application in the near future.

肝脏缺血再灌注损伤(IRI)及肝切除（HP）后，探究减轻损伤促进肝修复再生的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IRI促进肝修复再生，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广泛细胞间交流，提示细胞之间直接接触是其另一重要作用机制。故本研究从细胞连接入手，拟通过模拟IR和HP联合模型的体内外实验，通过活体示踪MSCs，来进一步验证：MSCs促进肝修复再生的方式（包括隧道纳米管连接，微囊泡，细胞融合等）以及下游信号通路启动肝脏再生的机制；明确MSCs 的分布规律与肝脏再生的相关性，进而探究通过基因修饰等方式提高MSC疗效的可行性。

探究减轻肝脏缺血再灌注损伤（Hepatic ischemia reperfusion injury ,HIRI）的新策略可以帮助肝脏外科术后的肝功能恢复。在临床研究中，通过MSCs细胞输注可以减轻缺血再灌注损伤，并且局部输注较外周静脉输注，减少肺部细胞静脉阻塞，提高归巢率，疗效更好。表明MSCs在损伤部位聚集与其修复作用有所关联。我们前期研究发现MSC与损伤肝细胞之间存在广泛细胞间交流，这提示了，除旁分泌作用以外，MSCs还可能通过细胞间的直接接触发挥作用减轻损伤。近年研究表明，MSCs来源的线粒体对组织损伤有修复作用，而缺血再灌注损伤与细胞中线粒体的损伤息息相关。.我们观察到，MSCs可以通过直接接触的方式，利用隧道纳米管连接，传递MSCs来源的线粒体，在体内，体外实验中减轻肝脏细胞的凋亡，缓解肝脏损伤，促进肝脏再生。较高浓度的MSCs来源的线粒体传递的治疗效果较好。同时，MSCs还可以通过胞外囊泡（包括微囊泡，外泌体等）的方式，传递MSCs来源的线粒体，减轻肝脏细胞的凋亡及HIRI损伤。MSCs来源的线粒体对组织损伤表现出了新的治疗潜力，对我们探究可能的新的治疗方式，提供理论基础和指导。.并通过纳米造影剂，活体示踪MSCs，明确MSCs 在修复受损组织的具体运动和分布情况，不仅可能为制订MSCs 临床方案提供理论依据，同时还为探讨MSCs减轻IRI 作用机制及其在治疗其他疾病的临床应用研究上提供有效手段。