The Contribution of Meckel's Cartilage-Derived Type II Collagen-Positive Cells to the Jawbone Development and Repair.

Jawbones and long bones, despite their shared skeletal lineage, frequently exhibit distinct origins and developmental pathways. Identifying specific progenitor subsets for mandibular osteogenesis remains challenging. Type II collagen is conventionally associated with cartilaginous structures, yet our investigation has identified the presence of type II collagen positive (Col2⁺) cells within the jawbone development and regeneration. The role of Col2⁺ cells in jawbone morphogenesis and repair has remained enigmatic. In this study, we analyze single-cell RNA sequencing data from mice jawbone at embryonic day 10.5. Through fate-mapping experiments, we have elucidated that Col2⁺ cells and their progeny are instrumental in mandibular osteogenesis across both fetal and postnatal stages. Furthermore, lineage tracing with a tamoxifen-inducible CreER system has established the pivotal role of Col2⁺ cells, marked by Col2-CreER and originating from the primordial Meckel's cartilage, in jawbone formation. Moreover, our research explored models simulating jawbone defects and tooth extraction, which underscored the osteogenic differentiation capabilities of postnatal Col2⁺ cells during repair. This finding not only highlights the regenerative potential of Col2⁺ cells but also suggests their versatility in contributing to skeletal healing and regeneration. In conclusion, our findings position Col2⁺ cells as essential in orchestrating osteogenesis throughout the continuum of mandibular development and repair.