During murine craniofacial development, the frontal bones of the skull are derived from neural crest cells, whereas the parietal bones are derived from the mesoderm. It has been postulated that the joints between these bones, known as sutures, represent a stem cell niche that helps facilitate bone repair in adulthood. Here, Daniel Doro, Sachiko Iseki, Karen Liu and colleagues employ lineage tracing in mouse embryos to label neural crest-derived cells and verify that postnatal frontal and parietal bones maintain their tissue origin. They go on to confirm previous suggestions that the frontal bones heal more efficiently than the parietal bones. However, when injuries are made in close proximity to a suture, these differences in healing efficiency are abolished. The authors find that, during healing, the repair sites are populated by neural crest-derived cells, even when the injury is made in mesoderm-derived bone. Finally, they show that all sutures in the skull contain cells expressing the stem cell markers Gli1 and Axin2. Overall, this work suggests that neural crest-derived progenitors play a key role in skull repair following injury; cranial injuries occurring close to the sutures may have better access to these progenitors and thus undergo more efficient repair.
