骨髓间充质干细胞提高缺血性脑卒中病灶部位髓鞘化水平的相关分子调控机制探究

Bone marrow derived mesenchymal stem cell (BM-MSC) transplantation has great potential in the treatment of ischemic stroke,but the therapeutic mechanisms are not toallyclear.Some previous studies showed that severe demyelination was found in ischemic stroke. And our preliminary work demonstrated the inhibitory effect on microglias mediated inflammation in vitro by BM-MSCs. Thus, we speculate the transplanted BM-MSCs may perform the same role in vivo followed with reduced death of oligodendrocytes and higher level of myelination. And subsequent job is to find out the associated signaling pathway simplicated in the inhibition of microglias by BM-MSCs. Another important factor highly associated with the level of myelination in the lesions is the migration and differentiation of oligodendrocyte progenitor cells (OPCs) from the subependymal zone and the dentate gyrus. Another group discovered in a chronic demyelination model that BM-MSCs promoted a portion of OPCs’ migration towards the transplatation site. This indicated that BM-MSCs only activated part of the OPCs’ migration related signaling pathways, most of which will be identified in the subsequent job. Hence, it is necessary to search for the other signaling pathways associated with the OPCs’ migration which can't be activated by BM-MSCs. Then we can expect to employ various auxiliary measures such as medicine to open these signaling pathways to further improve the effect of the treatment of ischemic stroke by BM-MSCs.

骨髓间充质干细胞（BM-MSCs）治疗缺血性脑卒中具有很大的潜力,但其治疗机制尚不完全明了。有工作表明缺血性脑卒中伴有严重的脱髓鞘现象。而我们前期体外实验表明，干细胞对小胶质细胞介导的炎症反应具有抑制作用。因此，BM-MSCs在体内可能通过调控炎症水平来减少少突胶质细胞的死亡发挥降低脱髓鞘水平的作用。我们也将检测BM-MSCs抑制小胶质细胞激活的信号通路。与病灶部位髓鞘化相关的另一个重要因素是室管膜下区和齿状回区少突胶质祖细胞(OPCs)向病灶部位的迁移及分化。有文献报道，在脱髓鞘模型中发现BM-MSCs促进了部分OPCs向移植部位的迁移。这表明BM-MSCs只激活了部分与OPCs迁移相关的信号通路。因此，为了进一步提高病灶部位的髓鞘化水平，有必要寻找与OPCs迁移有关但不被BM-MSCs激活的其他通路，并使用药物等辅助措施来开放这些通路以进一步提高BM-MSCs治疗缺血性脑卒中的效果。

缺血性脑卒中是一种具有高死亡率、高致残率的疾病，严重危害人类健康。目前的除了溶栓治疗外，没有其他更为有效地治疗手段。溶栓治疗具有狭窄时间窗的限制，即使接受了及时的溶栓治疗，致残率仍然很高。骨髓间充质干细胞（BMSCs）是一种非常有前景的治疗方法，可在缺血组织修复中发挥抗凋亡和营养作用。我们研究了治疗之前预处理BMSC，作为增加移植BMSC存活率和改善其基于细胞功能的新策略。我们在研究过程中意外的发现鼠神经营养因子（M-NGF）对BMSC的营养因子分泌具有抑制作用。其次，我们探索了高脑源性神经营养因子（BDNF）分泌型骨髓间充质干细胞的获取方法。最后，我们证实了BMSC可以提高缺血性脑卒中病灶部位髓鞘化水平。我们得到以下实验结论：1.自噬诱导剂海藻糖（Tre）被用作BMSC的预处理，可保护BMSCs细胞免受H2O2诱导的细胞活力降低和凋亡的影响。2.在体外，Tre通过激活AMPK信号通路来促进BMSC自噬。3.3-MA抑制Tre诱导的自噬，阻止了Tre预处理对H2O2诱导的细胞凋亡的保护作用。4.Tre预处理可增加BDNF，VEGF和HGF的分泌。5.在体内，与未经预处理的BMSCs相比，用Tre预处理可以进一步提高BMSCs的细胞存活率，减小梗塞面积，减轻细胞凋亡，增加血管生成，上调神经营养因子的表达并最终改善细胞移植后的功能恢复。6. 神经营养因子（M-NGF）能抑制骨髓间充质干细胞BDNF、GDNF营养因子的分泌。7. 共同使用d-cAMP、hb-FGF、PDGF-AA、Heregulin β1四种药物可诱导BMSC使其BDNF分泌量明显增加。8. BMSC可以募集少突胶质祖细胞迁移并分化为成熟的少突胶质细胞，促进髓鞘再生。