Identification of human tooth germ ectomesenchymal stem cells.

Cranial neural crest cells (CNCCs) contribute to most cranio-maxillofacial mesenchymal tissues, including the dental ectomesenchyme. However, the developmental relationships between human CNC-derived progenitors and the odontogenic lineage remain incompletely understood. Here, we mapped the single-cell transcriptomic landscape of prenatal human mandibles and reconstructed the putative differentiation trajectories of CNC-derived ectomesenchymal populations. Notably, we identified a distinct population of SLITRK6+ cells enriched in the odontogenic ectomesenchyme. These cells were detected in prenatal tooth germs and postnatal dental progenitor niches, including the apical papilla and dental follicle, but were rare in mature dental tissues. Functionally, SLITRK6+ cells exhibited enhanced clonogenic and odontogenic capacities and supported dentin-like matrix formation, pulp-dentin complex regeneration, and alveolar bone repair. SLITRK6 knockdown impaired odontogenic differentiation and reduced SMAD1/5/9 phosphorylation, suggesting potential involvement of BMP/SMAD signaling. Collectively, these findings identify SLITRK6+ tooth germ ectomesenchymal stem cells as prospectively isolatable progenitor populations associated with human dental development and regeneration.