VEGF/mTOR 信号通路对脂肪干细胞治疗下肢缺血调控机制的在体研究

Peripheral arterial disease (PAD) patients are often poor candidate for surgery due to old age and complication lesions, which can lead to high rate of clinical disability. Stem cell transplantation has become a new strategy for PAD treatment. However, inflammation in the ischemic area can lead to acute death a large number of transplanted stem cells, while exact target of residual cells for tissue regeneration is not yet clear. The uncertainty of mechanism contributes to a serious hurdle for the clinical translation of PAD stem cell therapy. Whether targeting molecules and signaling pathway associated with cell survival, repair and inflammation can effectively regulate the PAD stem cell therapy? Previous studies show that stem cells can activate VEGF/mTOR signaling pathway, which can control the cell survival, inflammation and angiogenesis. Accordingly, VEGF/mTOR pathway may play a role in transplanted stem cell survival and its therapeutic effect. Therefore, to the major problems of PAD cell therapy, we intend to invasively track the transplanted adipose-derived stem cells (ADSC) in ischemic hindlimbs by in vivo multi-modality molecular imaging strategies in the current project.We also want to evaluate the role of VEGF/ mTOR signal pathway in ADSC-induced regulation of inflammation and angiogenesis. Furthermore, by regulating the VEGF / mTOR pathway, we try to optimize the survival and treatment benefits of transplanted ADSCs. The aim of the project is to provide a strong scientific evidence and strategies for the translational medicine of PAD stem cell therapy.

外周动脉病（PAD）患者往往由于高龄、病变复杂等因素失去手术机会，导致临床高致残率。干细胞移植已成为治疗PAD 的新策略。然而，缺血区的炎症反应可导致大量移植干细胞的急性死亡，残存细胞再生修复作用的确切靶点尚不明确，严重阻碍PAD 干细胞治疗的临床转化。能否针对移植细胞存活和炎症修复的相关分子靶点和信号通路，实现干细胞治疗的有效调控呢？研究证据表明干细胞可激活VEGF/mTOR 信号通路，该通路与细胞存活、炎症反应和血管新生密切相关，可能是移植干细胞存活并发挥治疗作用的纽带。因此，本项目针对PAD 干细胞治疗的主要障碍，拟应用多模态分子影像技术，在体、无创评价脂肪干细胞（ADSC）治疗PAD 下肢缺血过程中VEGF/mTOR 信号通路的调控作用，旨在进一步通过VEGF /mTOR 信号通路的干预，实现移植ADSC 的在体功能性存活和治疗效应的优化，为PAD干细胞治疗转化医学提供有力科学依据

脂肪源性干细胞（ADSCs）具有迁移到损伤部位并通过促进血管生成来促进组织修复的能力，但糖尿病患者的脂肪干细胞的治疗效果由于氧化应激而受损。因为糖尿病以代谢紊乱为主要表现表现，而线粒体是活性氧ROS的主要来源，因此线粒体可能在糖尿病ADSC（dADSC）功能障碍的诱导中起重要作用。从糖尿病小鼠中分离的ADSCs用线粒体ROS清除剂mitoTEMPO或通用ROS清除剂 TEMPO处理三代出，其结果表明，mitoTEMPO预处理可使dADSCs的增殖、多分化潜能以及迁移和促血管生成能力提高到与对照组ADSCs相似的水平，而TEMPO预处理的作用则较小。mitoTEMPO预处理机械性地增强了dADSCs的线粒体抗氧化能力，而超氧化物歧化酶的敲除则降低了线粒体的抗氧化能力并减弱了血管生成能力。此外，mitoTEMPO预处理可提高糖尿病严重肢体缺血小鼠dADSC的存活率，显示出与对照ADSCs相似的保护作用。mitoTEMPO预处理dADSCs减轻糖尿病严重肢体缺血小鼠的肢体损伤并改善血管生成。这些结果提示，用线粒体ROS清除剂短期预处理dADSCs可恢复其正常功能，这可能是提高ADSC治疗糖尿病疗效的有效策略。