缺氧ucMSC源性外泌体mir-23a/miR-125b通过调控内皮细胞功能参与创面修复的机制研究

Stem cell-based engineered skin substitutes can effectively promote wound repair; however, the mechanism of interaction between stem cells and host tissues remains largely unknown, which greatly affects the clinical efficacy and safety of stem cells. We previously found that ucMSC encapsulated GelMA hydrogel significantly accelerated wound healing and angiogenesis of dermal layer. We further discovered that hypoxic ucMSC-derived exosomes mediated the migration and tube formation of endothelial cells, and exosomal miR-23a and miR-125b were remarkably induced by hypoxia. Accordingly, we hypothesized that under hypoxia condition, ucMSC-derived exosomal miR-23a and miR-125b were uptaken by endothelial cells, which in turn regulated endothelial cell function and wound healing process. Based on previous studies, we will further explore the molecular mechanism of the interaction of ucMSC-derived exosomes with endothelial cells, and clarify the effect of ucMSC-derived exosomes or microRNA encapsulated GelMA hydrogels on wound healing. Our study will uncover the interactions between seed cells and host cells, and provide a new strategy for exosome-based wound repair and the theoretical basis for clinical application of GelMA hydrogel.

基于干细胞的组织工程皮肤可以有效促进创伤修复，但干细胞与宿主组织之间的相互作用机制还远未阐明，极大影响了其临床应用的安全性和稳定性。我们前期研究发现，GelMA水凝胶载ucMSC能显著促进创面愈合及真皮血管形成，进一步体外实验证实，缺氧诱导的ucMSC源性外泌体介导了内皮细胞的迁移和成管。高通量芯片筛选分析发现缺氧促进了ucMSC源性外泌体miR-23a/125b的表达。据此推测：在创面缺氧微环境中，ucMSC通过外泌体传递miR-23a/125b调控内皮细胞的功能，进而参与创面修复。本项目拟进一步在分子和细胞水平上探讨ucMSC源性外泌体miRs调控内皮细胞功能的分子机制，在动物水平上明确GelMA/ucMSC源性外泌体或miRs复合水凝胶对创面修复的作用，为基于外泌体的创面修复提供新策略，也为GelMA水凝胶的临床应用奠定理论基础。

缺氧是最常见的皮肤创面微环境。我们之前的研究发现，在三维水凝胶中共培养脐带间充质干细胞（ucMSCs）和内皮细胞构建的工程化类皮肤中，细胞间通讯增强，其与宿主组织整合性也更好。因此，本课题旨在探索缺氧微环境下ucMSCs与内皮细胞的相互作用机制。我们发现，缺氧微环境下，ucMSCs能够通过旁分泌效应促进内皮细胞的增殖和迁移，该作用是由外泌体介导的。在小鼠全层皮肤损伤模型中，ucMSCs分泌的外泌体能够被内皮细胞摄取并促进创面修复；与常氧性外泌体相比，缺氧性外泌体能够促进细胞增殖，抑制细胞凋亡。其具体分子机制如下：缺氧诱导ucMSCs中miR-125b转录水平增加，其被装载至外泌体中并被内皮细胞摄取。在内皮细胞中，miR-125b被释放并靶向抑制了TP53INP1的表达，进而抑制了缺氧诱导的内皮细胞凋亡。抑制miR-125b和TP53INP1的相互作用会破坏缺氧性外泌体的保护效应。最后，我们在小鼠全层皮肤损伤模型中进一步明确，局部注射人工合成的agomiR-125b能够促进体内创面愈合。本项目揭示了缺氧条件下ucMSCs和内皮细胞通过外泌体miR-125b/TP53INP1信号轴促进创面愈合的新机制，为缺氧性外泌体及miR-125b在创面修复中的应用提供了强有力的理论基础。