ETV1/5在ES-ECs成釉细胞向分化中的调控机制研究

牙发育完成后成釉细胞程序性凋亡，成体内没有牙源性上皮干细胞用于釉质再生。人胚胎干细胞是具有多向分化能力的多能性干细胞，是釉质再生可能的种子细胞来源。本课题组前期研究发现人胚胎干细胞来源的上皮细胞（ES-ECs）在人胚牙间充质细胞的成牙诱导信号作用下表达釉原蛋白并形成蕾状上皮样结构，具有一定的成釉细胞向分化潜能；基因芯片结果显示转录因子Etv1和Etv5的基因表达水平在分泌期成釉细胞内显著性降低。本课题拟根据前期基因芯片结果采用相关分子生物学手段，构建人牙胚发育过程中成釉关键基因的表达谱；并研究慢病毒介导的转录因子Etv1/5基因表达水平改变对ES-ECs的成釉细胞向分化的调节作用及其机制；进一步利用人胚牙间充质细胞的成牙诱导信号，通过体外三维共培养/体内肾囊膜下移植手段，探索基于基因修饰的ES-ECs的成釉细胞再生系统。通过本项目研究完善成釉细胞再生体系及上皮-间充质信号对话系统。

The demand for bioengineered teeth or hard dental tissue, including enamel and dentin is increasing as tooth loss and dental defects constitute a prevalent health issue in dentistry. The key to tooth regeneration is reconstitution of the signaling in tooth development and availability of tooth forming cells. Dental enamel cannot regenerate itself since enamel forming ameloblasts commit apoptosis once tooth eruption. Lacking of human dental epithelial stem cells in adult body constrains the progressing of cell based enamel regeneration. Human embryonic stem cells (hESCs), pluripotent cells that are capable of differentiating into any cell types in human body,hold great promise to regeneration medicine and could be an ideal source of ameloblast regeneration. Our previous studies indicated that the hESC-derived epithelial cells (ES-ECs) have the potential to differentiate into ameloblast-lineage cells by secreting enamel forming extracellur matrix under odontogenic inductive signaling of human fetal dental mesenchymal cells. Microarray data showed the expression level of transcription factor Etv1 and Etv5 between non-dental oral epithelial cells and different stages of ameloblast-lineage cells are significantly different. In this present study, we aim to establish the amelogenesis-associated key gene expression profile, and investigate the role of Etv1 and Etv5 in regulating ameloblastic differentiation of ES-ECs and the underling potential mechanisms; Besides, we aim to utilize the odontogenic inductive ability of human fetal dental mesenchyme to engineer the gene modified ES-ECs into further ameloblastic differentiation and proceed futher histogenesis and morphogenesis. By carrying out this present study, we aim to improve our previous enamel-forming cells regeneration system and the signaling between epithlium and mesenchyme.