周围交感神经控制骨髓间充质干细胞再生修复牙周损伤的机制研究

The progress that injury activate resident stem cells and recruit stem cells derived from bone marrow is a key part of tissue regeneration. However, the mechanism of mobilization, migration and homing of bone marrow mesenchymal stem cells (MSCs)responded to damage signaling is still to be elucidated. Recent research has shown that local tissue injury could result in stem cells in bone marrow in a transition state of activation. Our research has proved that the signal of peripheral sympathetic nerves mediated by ADRB2 could control the activation of stem cells and influence the regeneration of tissue injury. In addition, we have reported MSCs could be recruited by injury in periodontal tissue and participate in the repaired tissue. In our project, we will plan to construct the modelling of the periodontal tissue injuries and explore the roles of MSCs in the regeneration of damaged tissue under the command of the signal of peripheral sympathetic nerves. We wish to testify the regulation of peripheral sympathetic nerves on MSCs by bone marrow transplantation with ADRB2-/- mice and wild type mice, which could further verify the roles of MSCs in regeneration of damaged tissue. Moreover, small molecular compounds which target the signal of peripheral sympathetic nerves will be used to regeneration for studying the possibility for clinical appliance. In conclusion, our project not only illuminates the way MSCs responded to periodontal tissue injuries, but also provides experimentalevidence for damaged tissue regeneration through mobilizing MSCs in bone marrow under sympathetic control.

组织局部的干细胞活化和骨髓的干细胞动员是组织损伤修复的关键环节，其中骨髓间充质干细胞（MSCs）通过动员、迁移、归巢等生物学行为参与组织再生的调控机理是近期国际研究热点。最新研究发现局部组织损伤可使全身的干细胞都处于一种活化临界状态，而我们研究证明周围交感神经可以通过ADRB2信号通路控制干细胞活化，并且发现MSCs能被动员参与牙周损伤的修复。目前能否通过调控周围交感神经信号促进MSCs活化动员参与牙周损伤的再生修复尚未见报道。本项目拟采用交感神经信号干预、干细胞荧光示踪技术、骨髓移植嵌合、ADRB2基因敲除小鼠模型等研究方法，选择牙周损伤动物模型为研究对象，对MSCs的活化、归巢和再生潜能以及交感神经调控ADRB2的分子途径进行系统研究。本课题不仅阐明了牙周组织损伤修复中MSCs活化动员的分子机理，而且从周围交感神经信号控制干细胞活化的角度为组织损伤治疗提供了实验依据。

全牙再生的实现既是一项世界性的科研难题，也是口腔医学科研工作者的最终目标。我们基于对成体牙组织结构的认识，从牙根、牙体、牙髓、牙周的角度，借助组织工程技术，重新理解了如何实现全牙再生这一难题。本课题从神经调控间充质干细胞层面，利用独创的干细胞聚合体技术，探讨牙周组织的再生修复难题。①通过比较研究发现截断感觉神经可以明显影响牙齿形态结构的形成，提示感觉神经在大鼠下切牙生长发育内稳态维持中发挥了主要作用，而交感神经无明显作用。②调控周围交感神经能显著激活骨髓间充质干细胞，但交感神经的活化会抑制H型血管新生，进而影响间充质干细胞分化，造成骨质疏松。③感觉神经阻断会抑制牙相关间充质干细胞的自我更新和分化能力，抑制作用主要依赖于Wnt信号通路；交感神经对骨髓间充质干细胞的作用主要依赖于ADRB2受体介导的PKA信号通路。④由于国内临床骨髓间充质干细胞缺乏，结合课题负责人的口腔医学背景，考虑到临床转化的需要，课题采用了更贴近神经嵴来源的脱落乳牙干细胞用于牙相关组织再生修复，课题不仅完成了全长牙髓再生的临床转化研究，而且利用完全脱位牙模型完成了牙周再生修复的临床前及临床转化研究。本课题进展顺利，特别是在口腔医学临床转化应用方面已走在了国际前沿行列。本课题在Science Translational Medicine等国际权威期刊发表SCI论文16篇，培养硕士3名，参加国内特邀学术报告3人次，获得2017年陕西省科学技术一等奖1项，相关研究成果入2018年中国医药生物技术十大进展。