缺氧预处理技术通过SDF-1α/CXCR4信号轴调节动脉内干细胞移植治疗犬脑梗死的机制研究

Stem cell therapy could improve the functional outcome after stroke, however the inflammation factor released after infarction would influence the survival of transplanted stem cell and the further therapeutic effect. Recent studies indicated that hypoxic precondition could improve the tolerance of bone mesenchymal stem cell (BMSC) to inflammatory and anoxic circumstance, and improve the therapeutic effect. However, some controversies still exist. ① Many studies were performed in rodent which has different neuroregulation from the human. ② The mechanism of the therapeutic effect improvement of hypoxic-preconditioned (HP) BMSC transplantation therapy was still not clear. Recently, some studies pointed that the SDF-1α/CXCR4 axis might play an important role in this process. Our preliminary experiment results suggested that the expression of CXCR4 in HP-BMSC was much higher than that in routine BMSC. Therefore we supposed that intra-arterially transplantation of HP-BMSC could further improve the therapeutic effect of stem cell therapy on cerebral infarction, and the SDF-1α/CXCR4 axis played an important role in this process. To confirm our hypothesis, our current study aims to study the protective effect of HP-BMSC to the neuron-like PC12 cell in the simulative post-infarction circumstance; to study the treatment efficiency of intra-arterially transplantation of HP-BMSC for the cerebral infarction, further to optimize the time window of BMSC transplantation and number of transplanted BMSC; to elaborate the role of SDF-1α/CXCR4 axis in these processes based on embolic canine stroke model.

干细胞移植治疗可改善脑梗死预后，但梗死后急性期释放的炎症因子会影响干细胞的存活及疗效。研究认为对骨髓间充质干细胞（BMSC）进行缺氧预处理（HP）能提高其对炎症缺氧环境的耐受，提高疗效。但存在一些问题：①常用实验动物鼠与人脑差异较大；②未能阐述HP-BMSC提高疗效的机制。最新研究发现基质细胞衍生因子-1α（SDF-1α）/趋化因子受体4（CXCR4）信号轴在HP过程中反应活跃，我们预实验也提示HP-BMSC细胞表面CXCR4受体表达显著增加。由此提出假说：经动脉移植HP-BMSC能提高干细胞移植治疗犬脑梗死的疗效，且SDF-1α/CXCR4信号轴发挥重要作用。为验证假说，我们拟通过体外实验研究HP-BMSC对神经元样细胞的保护作用；体内研究动脉内移植HP-BMSC治疗脑梗死的疗效，对移植时间窗和剂量的优化作用，并阐述SDF-1α/CXCR4信号轴在其中的作用机制。

脑梗死是临床常见病。干细胞移植治疗脑梗死是目前研究的主要方向之一，但脑梗死后继发性的炎性反应是制约干细胞移植治疗脑梗死的重要瓶颈。对干细胞进行预处理可以提高干细胞对炎性环境的耐受性，从而提高干细胞存活率，增强其治疗效果。但是缺氧预处理能否增强干细胞的治疗效果尚未可知，且相关的分子机制也不明确。在本项研究当中，我们分离提取了大鼠来源的骨髓间充质干细胞，并对其进行了缺氧预处理。然后基于大鼠大脑中动脉栓塞模型，移植干细胞条件培养基进行干预，并通过影像学和病理学方法评价治疗效果。此外，我们对培养基治疗脑梗死的机制进行了一些探讨并且通过质谱分析和蛋白芯片分析培养基中的成分。我们的结果表明：缺氧预处理可以增强骨髓间充质干细胞活性；单纯移植干细胞条件培养基能够治疗脑梗死，且缺氧预处理后疗效进一步增强；干细胞条件培养基的疗效可能与其抗凋亡和促进血管新生有关；通过蛋白组学分析，我们也发现了一些潜在的可能在脑梗死治疗中发挥积极作用的蛋白靶点。上述研究结果为进一步明确缺氧预处理技术提高干细胞移植治疗脑梗死疗效和相关作用机制提供了新的实验理论证据。