微胶囊包装WNT3A和BMP7诱导自体干细胞归巢再生牙本质

Dentin defects result from dental caries or trauma are one of the major causes for tooth loss. Currently, an endodontic treatment is delivered to remove infected pulp and dentin in tooth crown and on root canal wall, leaving a weakened tooth that is susceptible to fractures. The cell homing based strategy overcomes major translational hurdles that stem cell-based therapy suffers from. One critical barrier of cell homing based strategy is the deficient understanding of the factors driving dentinogenesis. Previous Work demonstrate Canonical Wnt and Bmp signaling are activated in odontoblast and synergistically promote dentinogenesis We aim to: microencapsulate pivotal factors, Wnt10a and Bmp7 for the specification of odontoblasts and osteoblasts from global gene expression profiles and regenerate dental pulp and dentin in vivo using selected factors by homing of endogenous cells that induce dentinogenesis in miniature pig model. The selected genes could be pivotal for odontoblast specification/differentiation from mesenchymal stem/progenitor cells, and orchestrate dental pulp/dentin regeneration, as a microencapsulated, translatable medical device free of cell transplantation.

龋齿或牙外伤导致的牙本质缺失是牙缺失的主要原因之一。常规根管治疗导致患牙失活、牙折等并发症机率增高。利用干细胞归巢策略进行牙本质再生可克服干细胞移植方法的问题，但难点是诱导干细胞归巢并定向分化为成牙本质细胞及诱导牙本质形成的关键基因尚不清楚。本课题组发现成牙本质细胞高表达Wnt10a和Bmp7基因，TOPGAL转基因小鼠证实Wnt和Bmp信号通路在成牙本质细胞激活，体外实验证实Wnt10a和Bmp7诱导干细胞迁移并向成牙本质细胞分化，并且两信号通路发挥协同作用。以上实验证明Wnt10a和Bmp7为成牙本质细胞分化高度相关基因。本研究拟利用PLGA微胶囊缓释成牙本质细胞分化高度相关基因表达蛋白，复合支架材料诱导自体干细胞归巢，在小型猪切牙模型原位再生牙本质。在优化蛋白浓度与实验时间前提下，再进行感染根管牙本质再生研究。本研究有望证实成牙本质细胞分化高度相关基因可有效诱导干细胞归巢并再生牙本质。

牙髓及牙本质再生策略可能是牙髓病等导致的牙本质缺失传统治疗方法的全新替代治疗方案。本课题组前期研究发现成牙本质细胞高度表达BMP7和Wnt10a基因。BMP和典型Wnt信号通路在体外发挥协同作用促进牙本质形成。为了明确Wnt和BMP可有效诱导的牙髓及牙本质再生，本课题将目的基因投递进入严格按照根管治疗程序去除牙髓及部分牙本质壁的小型猪下颌切牙。利用组织学及免疫组织化学、MicroCT、扫描电镜（SEM）和纳米压痕硬度测试等方法，对再生牙髓及牙本质的组织学与影像特点进行定性/定量分析；证实了再生牙本质具有成牙本质细胞突起这一特征性超微结构；对再生牙本质的生物力学特性与天然牙本质进行对比。证实小型猪下颌切牙是牙髓及牙本质再生实验的良好模型；BMP7和Wnt10a诱导干细胞归巢再生的牙髓及牙本质与天然牙髓牙本质的形态学及生物力学等特性相当。本研究为干细胞归巢再生牙髓牙本质临床转化研究奠定基础。