Postdoctoral Fellow Centre for Regenerative Medicine and Health, Hong Kong Institute of Science & Innovation (CAS) Hong Kong, China (People's Republic)
Abstract: Odontogenesis begins with the invaginated ectoderm-derived dental epithelium, which is surrounded by condensed neural crest-derived mesenchyme. This process involves sequential and reciprocal interactions, establishing an excellent system for understanding organogenetic mechanisms. While rodents, particularly mouse models, have provided insights into tooth development and tooth germ organoids, they do not fully represent human odontogenesis. Therefore, establishing human tooth germ organoids is essential for more accurately studying human odontogenesis and tooth regeneration. In early tooth development, odontogenic potential transitions from epithelial cells to mesenchymal cells. Given that dental mesenchyme originates from neural crest mesenchyme, our current experiment utilized human embryonic stem (hES) cells that first differentiated into neural crest stem cells（NCSC）, followed by differentiation into mesenchymal cells. In prior experiments, we identified a medium capable of maintaining the odontogenic potential of isolated mouse primary tooth germ mesenchymal cells in vitro, which we then applied during NCSC differentiation into mesenchyme. Our single-cell RNA sequencing experiments revealed that genes such as Barx1 were specifically expressed in mesenchymal cells after E12.5 days. These genes were also detected in hES-derived mesenchymal cells, indicating that these mesenchymal cells may possess odontogenic potential. By recombining ES-derived NCSC and mesenchymal cells with oral epithelial cells, we observed the formation of tooth germ-like structures following in vitro culture. Our findings provide valuable in vitro tools for investigating human tooth development and tooth-related diseases, enhancing research efficiency, and reducing the number of animals needed for in vivo studies.
