内源性GDF11调控牙源性干细胞分化影响牙发育及损伤修复的机制研究

Dental stem cell-based tooth regeneration is the futuristic treatment for missing teeth. Growth Differentiation Factor 11 (GDF11), a novel member of the TGF-beta superfamily, has been reported to play important role in regulating differentiation of various stem cells. Our previous work has shown that exogenous GDF11 stimulates osteoclastogenesis of bone marrow macrophages, while inhibits osteoblastic differentiation of bone marrow mesenchymal stem cells. However, the role of endogenous GDF11 during dental stem cell differentiation remains unknown. Our preliminary data, for the first time, showed that Gdf11 conditionally knocked out in the Gli1 positive dental mesenchymal stem cells resulted in short root defect and dentin hypoplasia. In the present project, we will utilize the inducible conditional knockout mice to confirm the effects of endogenous GDF11 on tooth root development and dentin repair. We will also employ the cutting-edge lineage tracing technique to observe odontogenic differentiation of dental stem cells in vivo. To further elucidate the underlying mechanism, we will culture the dental stem cells in vitro and perform functional experiments to verify whether specific knockout of Gdf11 regulates odontogenic differentiation by down-regulating the expression of Nfic, a key regulator of tooth root development. Finally, RNA sequencing will be carried out to identify unknown downstream target genes and signaling pathways. These results will hopefully add to the theoretical foundation for dental stem cell-based tooth regeneration.

基于牙源性干细胞的牙再生是未来修复缺失牙的治疗方向。生长分化因子11（GDF11）是TGF-β超家族新成员,在调控多种干细胞分化过程中发挥关键作用。申请人前期发现外源性GDF11能够促进破骨前体细胞的破骨分化同时抑制骨髓间充质干细胞的成骨分化，但内源性GDF11在牙源性干细胞分化过程中的作用尚未见报道。申请人前期发现在Gli1阳性的牙源性干细胞中特异性敲除Gdf11的小鼠表现为短牙根缺陷和牙本质发育不全。本研究拟利用诱导条件性敲除小鼠，结合体内谱系示踪观察牙源性干细胞的成牙本质向分化情况，明确内源性GDF11对牙根发育和牙本质损伤修复的影响；进一步分离培养牙源性干细胞，并通过功能实验明确特异性敲除Gdf11通过下调牙根发育关键调控因子Nfic的表达影响牙源性干细胞分化；最后，通过RNA测序探索GDF11的下游靶基因和信号通路。研究结果有望为基于牙源性干细胞的牙再生奠定理论基础。

基于牙源性干细胞的牙再生是未来修复缺失牙的治疗方向。生长分化因子11（GDF11）是TGF-β超家族新成员,在调控多种干细胞分化过程中发挥关键作用。本课题以GDF11作为切入点，按照原定计划实施，课题进展顺利，研究发现：（1）成人及野生型成年小鼠的牙髓组织中均有内源性GDF11的高表达。（2）敲降人牙髓干细胞中的内源性GDF11后，成牙本质向分化潜能、矿化能力和成牙本质相关基因表达均显著下降，而细胞的增殖和迁移无显著改变。经典的Wnt/β-catenin通路相关因子显著下调（3）GDF11抑制钛种植体骨结合并在年轻和老龄小鼠中观察到相似的结果，GDF11中和抗体可以显著提升老龄小鼠的种植体骨整合强度。（4）GDF11导致下颌骨骨量的丢失。.标注SCI论文共5篇，其中课题负责人第一作者1篇，通讯作者3篇，共同作者1篇，最高影响因子6.993，累计影响因子27.178，累计引用43次。共培养1名博士生毕业，2名硕士毕业；在此基础上，课题负责人获得中国博士后科学基金面上资助，四川省科技创新人才，国际种植牙学会（ITI）奖学金。