MG53调控SDF-1/CXCR4信号促进脐带干细胞治疗脑缺血再灌注损伤的机制研究

Cerebrovascular disease is one of the most common diseases with high mobility and mortality. For some patients, reperfusion may exacerbate the injury initially caused by ischemia, producing a so-called “cerebral ischemia-reperfusion injury (CIRI)”, so there has been no effective therapy. We previously showed that transplantation of human umbilical cord derived mesenchymal stem cells (hUC-MSCs) to hypoxic-ischemic brain injury model could ameliorate clinical symptom. However, the rates of cell survival and neuronal differentiation were pretty low. Recent studies show that MG53 is an essential component of cell membrane repair machinery for cardiac ischemic, kidney and lung protection. But, the protective effects of MG53 on hUC-MSCs and CIRI have not been reported. SDF-1/CXCR4 signal is a key factor, which regulates the migration and differentiation of stem cell. In this study, we will take rhMG53 as an entry point and SDF-1 / CXCR4 signaling inhibitor as a breakthrough to examine the protective effects of rhMG53 with different doses on the injury models of hUC-MSCs. The neuron-protection and neurogenesis (cell migration, survival, differentiation, apoptosis) of rhMG53 on MSCs transplanted into a rat model of cerebral ischemia-reperfusion injury were detected by flow cytometry, qRT-PCR, Western, immunofluorescence, Morris water maze, etc. Meanwhile, the signal inhibitor will be treated to explore the roles and mechanisms of SDF-1/CXCR4 signal on stem cell migration and brain function recovery. This study presents a theoretical hypothesis that rhMG53 improve cell outcome and efficacy of MSCs transplantation by regulating SDF-1/CXCR4 signaling, which will provide scientific bases and strategy for the application of stem cells and CIRI therapy.

脑血管病致残率和死亡率高，缺血区恢复再灌注会造成脑缺血再灌注损伤（CIRI），临床上无特效疗法。我们的前期研究发现脐带MSCs能改善脑损伤症状，但干细胞在损伤部位存活和分化效率低。MG53是细胞、心脏、肾和肺损伤保护的关键蛋白，但是MG53对脐带MSCs和CIRI的保护作用未见报道，而SDF-1/CXCR4信号是调控细胞迁移分化的关键因子。因此，本研究拟以rhMG53为切入点，以SDF-1/CXCR4信号抑制剂为突破口，通过体外实验观察rhMG53对脐带MSCs的损伤保护作用及量效关系；体内观察rhMG53对脐带MSCs植入CIRI后神经修复和神经再生的保护作用；同时，结合抑制剂探究SDF-1/CXCR4信号在MG53促进干细胞疗效中的机制。该研究旨在阐明MG53调控SDF-1/CXCR4分子信号影响干细胞微环境、重塑细胞命运的假设，为干细胞转化应用和CIRI的防治提供科学依据。

创伤性脑损伤（TBI）致残率和死亡率高，临床上无特效疗法。我们的前期研究发现脐带间充质干细胞（hUC-MSCs）能改善TBI症状，但干细胞在损伤部位存活和分化效率低。MG53是细胞、心脏、肾和肺损伤保护的关键蛋白，但是MG53对hUC-MSCs和TBI的保护作用未见报道，且分子机制不明。因此，本研究拟以rhMG53为切入点，通过体外实验观察MG53蛋白对hUC-MSCs和海马神经元（HT22）细胞的损伤保护作用及分子机制；体内实验检测MG53蛋白对hUC-MSCs植入TBI后神经修复和神经再生的保护作用。我们发现（1）MG53蛋白通过调控TLR4/NF-κB通路显著降低LPS对HT22和C57/BL6小鼠的神经毒性和神经炎症。（2）MG53蛋白能够提高hUC-MSCs的存活和迁移，MG53预处理能够提高hUC-MSCs的抗氧化能力，减低H2O2对hUC-MSCs的氧化损伤。（3）MG53蛋白和hUC-MSCs能够透过血脑屏障迁移到TBI小鼠损伤部位，治疗后能够增加小鼠体重，改善认知功能，增强学习记忆能力，提高神经恢复，减轻抑郁，抑制细胞凋亡，促进神经再生，提高抗氧化水平，而且联合治疗比单一治疗效果更加明显。进一步研究显示MG53蛋白和hUC-MSCs可能通过激活PI3K/Akt-GSK3β和ERK1/2信号通路对TBI小鼠发挥保护作用。因此，我们研究显示MG53对hUC-MSCs和HT22具有保护作用，还可以促进干细胞转归和重塑干细胞命运，对TBI的神经修复效果，为干细胞转化应用和TBI的防治提供科学依据。