趋化因子受体/Rho鸟苷三磷酸酶信号通路介导牙周再生间充质干细胞归巢的机制研究

Stem cell transplantation has been the predominant approach in regenerative medicine, unfortunately, this strategy encounters translational hurdles due to the limited availability of stem cell sources, the excessive cost of commercialization, and difficulties in clinical adoption and regulatory approval. The active attraction of endogenous mesenchymal stem cells (MSCs) that already exist in the body to sites of injury, known as cell homing, has the potential to provide new therapeutic options for in situ tissue regeneration. Tissue regeneration that relies on host stem cell homing, local tissue response, and functional stimulation offers new insights into in vivo tissue engineering and bioscaffold design. Although this approach raises the possibility of repair damaged periodontal tissue by recuiting the latent endogenous regenerative potential of the patient and may provide a tangible pathway toward clinical translation, cell homing remains a provocative approach in need of further experimental evidence. Of utmost importance is that the underlying mechanism that mediates MSC homing to a target site (such as the impaied periodontal defects) for endogenous regeneration remains unidentified. Based on our previous researches on the develop of MSC-recruiting scaffolds and conducting periodontal endogenous regeneration, we propose that the chemokine receptors and Rho GTPases (RhoA, Rac1 and Cdc42) are involved in the MSC homing process toward endogeous regeneration. In this project, we further optimize our biofunctional scaffolds by combining and regulating the delivery of multiple signalling molecules including growth factors and cell homing factors. Thereafter, in vitro and in vivo cell homing models will be established for evaluating the homing capacity of differently designed scaffolds. Based in vitro cell culture model, molecular biology testings and in vivo transplantation, an equation between the design parameters (i.e. growth factor combinations and release profiles) and funtion outcomes (i.e. cell behaviour and homing capacity) would be ontained. Briefly, the MSC-recruiting ability of the different cytokine-loading scaffolds will be assessed and those with the best ability will go into the next stage experiments. The expression profiles of chemokine receptors in MSCs will be confirmed, along with the roles of the chemokine receptors and Rho GTPases in MSC homing will be uncovered as well as the relationship between the chemokine receptors and Rho GTPases. Hopefully, the current project will increase our understanding on the molecular mechanism underlying the MSC homing in endogeous regeneration, and more importantly, theoretically guide the cytokine selection for the development regenerative biomaterials with strong cell-recruiting ability. These biomaterials will pave their way toward satisfactory endogenous regeneration of various tissues with complete structure and function.

牙周内源性再生为临床牙周病治疗和组织缺损修复带来新的希望。然而，间充质干细胞（MSCs）募集和归巢的分子机制尚不清楚。我们在生物材料"细胞募集性"设计的基础上，进一步探索趋化因子受体/Rho鸟苷三磷酸酶（RhoA、Rac1和Cdc42）信号通路介导MSCs归巢的机制。本项目拟进一步优化前期设计合成的仿生支架，构建体内外MSC归巢模型，采用细胞学、动物实验和分子生物学方法系统评价不同细胞因子组合体内外诱导MSCs归巢的功效，建立相应参数方程；探明MSCs所表达的趋化因子受体的种类，分析趋化因子受体和Rho鸟苷三磷酸酶分别或联合作用介导MSCs归巢中的机制，明确二者之间的上下游关系以及可能存在的反馈调节。本项目通过深入探索内源性再生过程中MSCs归巢的机制，为优化外源性细胞因子的筛选与组合、研发具有良好细胞募集能力的内源性组织再生支架材料，并最终实现多种组织的生理结构和功能的再生提供理论指导。

牙周内源性再生为临床牙周病治疗和组织缺损修复带来新的希望。然而，机体内源性间充质干细胞（MSCs）如何募集和归巢到达牙周缺损区域及其分子机制尚不清楚。本项目按照项目计划书所设计的研究内容，在生物材料“细胞募集性”设计的基础上，进一步探索了趋化因子受体/Rho鸟苷三磷酸酶（RhoA、Rac1和Cdc42）信号通路介导机体自身MSCs归巢达到治疗靶点的策略，剖析相关分子机制。本项目首先优化了课题组前期（国科金31170912）设计合成的仿生支架材料，成功构建出体、内外MSC归巢模型，采用细胞学、动物实验和分子生物学方法系统评价了不同细胞因子组合，体内外诱导干细胞归巢的功效，建立相应因子标准和材料合成的参数方程；明确了MSCs所表达的趋化因子受体的种类，揭示趋化因子受体和Rho鸟苷三磷酸酶分别或联合作用，介导MSCs归巢中的机制，并进一步阐释了二者之间的上下游关系以及可能存在的反馈调节。本项目通过深入探索内源性再生过程中MSCs归巢的策略和分子机制，为优化组织再生中，外源性细胞因子的筛选与组合、研发具有良好细胞募集能力的内源性组织再生支架材料，并最终实现多种组织的生理结构和功能的再生提供理论指导。本项目严格按照当初设计研究计划，圆满完成研究任务，获得的研究结果，共发表基金资助论文21篇。培养硕士研究生两名，博士研究生两名。项目负责人2016年入选教育部长江学者特聘教授，2017年入选科技部中青年科技创新领军人才，并进入2017年Elsevier出版集团公布高被引中国学者医学榜单。项目负责人作为团队带头人的“牙周组织工程与再生团队”获批2016年陕西省重点科技创新团队。

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