高表达miR-126的内皮祖细胞膜微粒通过刺激血管再生和改善组织微环境促进损伤修复的研究

The ability of tissue repair is impaired in patients with diabetes, osteoporosis and so on, which has become a major health problem. Improving angiogenesis, blood supply, microcirculation and tissue microenvironment in the repaired tissue should be the common therapeutic targets for wound healing. Evidence has shown that tissue repair could be promoted by endothelial progenitor cells (EPCs) through improving angiogenesis and microenvironment. However, the efficacy of EPCs could be decreased in pathological conditions. The microvesicles released from EPCs (EPC-MVs) could also exert the same or even better beneficial effects as EPCs. MiRNAs could be carried and transported by EPC-MVs to their recipient cells, and miR-126 in EPC-MVs is associated with their effects. Our previous study has found that EPC-MVs could promote the angiogenesis ability of EPCs and vascular endothelial cells (ECs) in vitro, and accelerate wound healing in animal models with defectives in tissue repair. Moreover, miRNA126 overexpression could enhance the cell protective effects of EPC-MVs. These suggest that miRNA126 overexpression may improve the beneficial effects of EPC-MVs. In this project, we will comprehensively investigate whether miRNA126-overexpression EPC-MVs (EPC-MVs-mi126) can greatly promote angiogenesis, improve tissue microenvironment, and accelerate wound healing in animal models of tissue injury, and the underlying mechanisms will also be explored. Therefore, this proposal has important theoretical and clinical significance.

组织修复能力在糖尿病、骨质疏松等病人中严重受损。加强新生血管生成，改善局部血供和微环境是治疗的共同靶点。内皮祖细胞(EPCs)能通过促进血管新生和改善微环境加速组织修复。然而在病理状态下，其作用受影响。EPCs释放的细胞膜微粒(EPC-MVs)也能发挥上述作用，并且效果可能更好。EPC-MVs能携带并传递miRNAs至靶细胞，其中miR-126与其细胞保护功能密切相关。我们前期研究发现，EPC-MVs可提高内皮细胞及EPCs血管生成能力，促进创伤愈合；miR-126高表达能加强EPC-MVs对细胞的作用,提示了miR-126过表达可能加强EPC-MVs的功能。本项目将在细胞及动物模型上深入研究miR-126高表达EPC-MVs对受体细胞功能的影响，对损伤组织血管生成及微环境的调节作用，及对损伤修复异常的治疗效果和机制。因此，具有重要的理论意义和应用价值。

组织修复能力在糖尿病、骨质疏松等病人中严重受损。加强新生血管生成，改善局部血供和微环境是治疗的共同靶点。内皮祖细胞(EPCs)能通过促进血管新生和改善微环境加速组织修复。然而在病理状态下，其作用受影响。EPCs释放的细胞膜微粒(EPC-MVs)也能发挥上述作用。miRNA是一类非编码小RNA，参与增殖、迁移、分化及凋亡等多种细胞功能。我们研究发现EPC-MVs促进前成骨MC3T3-E1细胞和人表皮细胞HaCaT的增殖、迁移、抑制MC3T3-E1细胞凋亡，降低HaCaT在高糖环境下的凋亡比率，解除高糖环境下对HaCaT细胞周期阻制，而miR-126高表达能加强EPC-MVs对受体细胞的作用，MVs-miR-126a对HaCaT细胞的作用机制可能通过ABCA1和CTND1信号通路发挥作用，而对MC3T3-E1细胞的作用机制通过Erk1/2-Bcl2信号通路发挥作用。随后，在糖尿病小鼠皮肤损伤模型中，证实EPC-MVs-miR126能加快皮肤损伤愈合，揭示miR-126过表达可加强EPC-MVs的功能。为了进一步弄清miR-126在组织修复上的作用，我们收集临床患有骨质疏松（OP）病人的血液样本，发现miR-126与OP之间呈正相关，并通过抑制BMSCs的细胞增殖，细胞周期活性和成骨分化，增强BMSCs细胞迁移，激活PI3K/Akt信号轴，动员BMSCs向EPCs分化，最终促进血管新生。最后，我们调整并延伸了部分实验，进一步阐明BMSCs来源的MVs通过改善骨组织微环境促进大鼠股骨缺损的愈合，并揭示MVs发挥作用的分子机制。本项目分别从临床，细胞和动物模型上深入研究miR-126及其MVs对受体细胞功能的影响，观察对损伤组织血管生成及微环境的调节作用，揭示其损伤修复异常的治疗效果和机制，为临床组织修复提供新途径和理论依据。