RAS对骨髓间充质干细胞参与创面修复的调控作用及机制初探

Optimum healing of a cutaneous wound requires a well-orchestrated integration of the complex biological and molecular events of cell migration and proliferation, and of extracellualr matrix deposition and remodeling. Several studies in recent years suggest that bone marrow derived stem cell such as mesenchymal stem cells may be involved in these processes, contributing to skin cells or releasing regulatory cytokines. Bone mrrow derived mesenchymal stem cells may be mobilized to leave the bone marrow, home to injured tissues and participate in wound repair and regeneration. However, the mechanism involved in these processes has not been fully understood. It has been demonstrated that skin is a source of and target organ for neuroendocrinological hormone. Growing evidence has revealed that renin-angiotensin system (RAS) as one of important hormones is closely associated with cutaneous wound repair and regeneration. Moreover, the existence of complete RAS in bone marrow has been recently demonstrated. More recently, we have found increased the production of angiotensin II, a key peptide of RAS in injured tissue and circulating system after wounding. Therefore, we hypothesize that the activited RAS as an injury-inducible messenger might not only stimulate the cell proliferation and mobilization in wounded sites, but also induce bone mrrow derived mesenchymal stem cell to leave the bone marrow, home to injured tissues and participate in wound repair and regeneration, which may be one of mechanisms that RAS infulences wound healing. To prove our hypothesis, we designed the experiment. In the present study, we will develop mouse full-thickness skin wound model to observe the effect of RAS on the mobilization, homing and secretion of bone marrow derived mesenchymal stem cells. We also will use the mice with damaged bone marrow function to develop cutaneous wound model, and infuse the bone marrow derived mesenchymal stem cells from EGFP transgenic mice into widetype mice to further observe the effct of RAS on the mobilization, homing and transdifferentiation of bone marrow derived mesenchymal stem cells. Meanwhile， mouse bone marrow mesenchaymal stem cells will be cultured to examine the effect of RAS on the mobilization, homing, secretion and transdifferentiation of bone marrow derived mesenchymal stem cells. Based on above-designed experiment, we will try to reveal the molecular mechanisms by which RAS as an important injury-inducible messenger influences wound healing through recruiting bone-derived mesenchymal stem cells into wounded sites. This study will be helpful to understanding the cellular and molecular mechanisms of wound healing, as well as improving the outcome of wound repair.

骨髓间充质干细胞(MSCs)在创面修复过程中扮演重要角色，但其在创伤后被动员、归巢及分化、分泌行为的调控因素尚未阐明。研究证明：神经内分泌因素在皮肤的自我更新、修复与再生中起重要作用；且肾素-血管紧张素系统（RAS）作为重要的应激激素与皮肤的损伤修复和再生密切相关，其与骨髓MSCs的关联性已倍受关注。我们最近研究发现：创伤后RAS被激活，组织和循环中的RAS重要成份水平升高，结合既往相关研究，推测：RAS对骨髓MSCs动员、归巢及分化、分泌行为存有调控作用，可能是RAS影响创伤愈合的机制之一。研究以小鼠骨髓MSCs为对象，结合皮肤缺损创面愈合模型，采用体外细胞培养、EGFP转基因小鼠骨髓MSCs输入、骨髓功能抑制等技术方法证明之，并初步探讨RAS对骨髓MSCs生物学行为影响的分子机制。研究结果将有助于阐明神经内分泌因素调控皮肤损伤修复的机制，并为丰富创面促愈手段，提高修复质量提供理论基础。

骨髓间充质干细胞(MSCs)在创面修复过程中扮演重要角色，但其在创伤后被动员、归巢及分化、分泌行为的调控因素尚未阐明。研究证明：神经内分泌因素在皮肤的自我更新、修复与再生中起重要作用；且肾素-血管紧张素系统（RAS）作为重要的应激激素与皮肤的损伤修复和再生密切相关，其与骨髓MSCs的关联性已倍受关注。我们最近研究发现：创伤后RAS被激活，组织和循环中的RAS重要成份水平升高，结合既往相关研究，推测：RAS对骨髓MSCs动员、归巢及分化、分泌行为存有调控作用，可能是RAS影响创伤愈合的机制之一。研究以小鼠骨髓MSCs为对象，采用体外细胞培养初步探讨了RAS对骨髓MSCs生物学行为影响的分子机制。. 在本课题的研究中，基本完成申请书中所列主要的研究内容，且获得了新的发现，为进一步的研究RAS在动员机体内源性修复机制中的作用打下良好的基础。. 研究过程中所得到的主要发现：. 1）．初步证实MSCs表达RAS的重要成分ACE、AT1和AT2受体，并有产生Ang II的能力，为进一步研究RAS与MSC之间的关系提供了理论基础。. 2）．首次证明RAS中重要的活性物质血管紧张素II促进了MSCs的增殖、迁移，以及分化为血管内皮细胞及上皮细胞。. 3）．首次发现并证实AngII可将MSC成上皮诱导分化率从40%提高到80%。探索并发现了Ang II促进MSCs成角质细胞分化的信号机制，即：Ang II通过JAK2、JNK、P38MAPK信号通路促进了MSC成角质细胞分化。. 通过完成本立项研究，我们初步证明RAS与MSC之间密切的关系，RAS中重要的活性物质血管紧张素II促进了MSCs的增殖、迁移，以及分化为血管内皮细胞及上皮细胞。本研究的完成初步揭示Ang II对MSCs的增殖，向创面的迁移，以及分化为修复所需细胞的影响可能是其促进创面愈合的机制之一。我们的研究为内分泌系统调控成体干细胞影响机体创伤组织修复与再生的假说提供证据，丰富创面愈合的内分泌调控机制，为改善组织修复的结局，提高修复质量和水平提供了新的思路。

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