高表达miR-17的EPC-EXs对糖尿病足的治疗作用及其机制研究

Diabetic foot lacks effective therapeutic methods. Protecting and regenerating endothelial cells (EC) and muscle cells is one of the important strategies for treating diabetic foot. The exosomes released from stem cells might be the responsible mechanism for stem cell-based therapy and could exert special advantage. Our previous study has found that exosomes released from endothelial progenitor cells (EPC-EXs) are rich in miR-126 that could improve EC function and promote angiogenesis, and also rich in SDF-1a/CXCR4 which are critical chemoattraction signals for promoting the homing of stem cells. In previous work, we found that EPC-EXs could promote endothelial cells (ECs) angiogenesis and proliferation and proliferation of skeletal muscle cells which impaired by hyperglycemia. We also found that EPC-EXs could enhance the blood perfusion of the ischemic limb of diabetic mice. In addition, miR-17 is down regulated in diabetes mellitus patients and plays important roles in angiogenesis. We preliminarily found that miR-17 overexpressed EPC-EXs (EPC-EXsmiR-17) contained rich miR-17 and higher level of SDF-1a/CXCR4, and could enhance the protective effects of EPC-EXs on endothelial cells and skeletal muscle cells. Therefore, in this project, we will study the role of EPC-EXsmiR-17 in protecting and regenerating vessels and muscles and the underlying mechanisms by using the cell and animal models. Successful completion of this propose will provide novel rationale and targets for diabetic foot therapy.

糖尿病足目前缺乏有效治疗手段，保护和再生血管和肌肉细胞是治疗糖尿病足的重要策略。干细胞外泌体（EXs）是干细胞发挥作用的重要途径，应用于治疗有多种优势。我们前期结果表明，内皮祖细胞外泌体（EPC-EXs）富含改善血管内皮细胞（ECs）功能和促进血管再生的miR-126，及干细胞归巢重要趋化信号SDF-1a/CXCR4；能保护高糖损伤的ECs及骨骼肌细胞的血管形成和增殖能力；并能改善糖尿病小鼠缺血后肢血流灌注。MiR-17在糖尿病患者中水平减低，对血管生成有重要作用。前期研究发现，高表达miR-17的EPC-EXs（EPC-EXsmiR-17）同时携带丰富的miR-17及更高水平的SDF-1a/CXCR4；对上述细胞功能有更好的保护作用。因此，本项目拟在细胞和动物模型上研究EPC-EXsmiR-17对血管和肌肉的保护和再生修复作用，并阐明相关机制，为有效治疗糖尿病足提供新方向和理论基础。

糖尿病足（DHI）目前缺乏有效治疗手段，保护和再生血管和肌肉细胞是治疗DHI的重要策略。干细胞外泌体（EXs）是干细胞发挥作用的重要途径，应用于治疗有多种优势。内皮祖细胞外泌体(EPC-EXs)富含改善血管内皮细胞（ECs）功能和促进血管再生的miRs；能保护高糖损伤的ECs及骨骼肌细胞的血管形成和增殖能力；并能改善糖尿病小鼠缺血后肢血流灌注。MiR-17在糖尿病患者中水平减低，对血管生成有重要作用。前期工作表明富含miR-17-5p的EPC-EXs(EPC-EXsmiR-17-5p )携带丰富的miR-17对上述细胞功能有更好的保护作用。因此，本项目首先研究EPC-EXsmiR-17-5p对DHI小鼠缺血下肢肌肉和血管的保护作用；然后研究对高糖及缺氧损伤血管内皮细胞ECs和成肌细胞C2C12功能的调控作用，并深入阐明相关机制。.我们发现在DHI小鼠缺血后肢血管和肌肉组织中miR-17-5p水平显著降低。输注富含EPC-EXsmiR-17-5p 能通过传递携带的miR-17-5p，显著增加缺血后肢血流灌注、微血管密度、毛细血管新生以及改善肌肉重量、张力和结构完整性，同时减少肌肉组织细胞凋亡。在高糖和缺氧损伤的血管内皮细胞(ECs)和成肌细胞(C2C12)模型中，我们发现EPC-EXsmiR-17-5p可以将其携带的miR-17-5p递送到受体细胞中，抑制靶细胞中SPRED1蛋白，激活PI3K/Akt信号通路发挥对损伤细胞的保护作用。本研究阐明，富含miR-17-5p的EPC-EXs通过SPRED1-PI3K/Akt通路保护血管内皮细胞和肌肉细胞功能，对DHI发挥治疗作用。.本项目共发表相关论文7篇，项目研究成果对基础及临床研究均具有较高的指导意义，为后肢血管和肌肉功能调控及DHI治疗研究提供新的靶标及策略，。有望开发成新的DHI治疗药物，成果的进一步应用将帮助改善DHI患者生活质量，减轻疾病为患者和社会带来的沉重负担，产生良好的社会和经济效益。