Young babies and newborn mice can naturally heal damage to the bones that form the top of the skull, but this ability is lost in adults. In a new study published in Proceedings of the National Academy of Sciences, University of Pittsburgh researchers developed a novel approach that promoted bone regeneration in mice without implantation of bone tissue or biomaterials. The technique uses a device similar to an orthodontic wire used to realign teeth to carefully stretch the skull along its sutures, activating skeletal stem cells that reside in these wiggly seams. In adult mice, the technique repaired damage to the skull that otherwise would not have healed on its own.
In mice, which have very similar skull development to humans, the researchers used a so-called bone distraction device to carefully apply a controlled pulling force to the calvarial bones, strong enough to slightly widen the sutures but not enough to cause a fracture. Using single-cell RNA sequencing and live-imaging microscopy, they found that the number of stem cells in the expanded sutures of these animals quadrupled. As a result, mice treated with the device regenerated bone to heal a large defect in the skull.
The researchers are investigating how their findings could be used to inform novel therapies in people, not just to heal skull injuries but also fractures in long bones such as the femur. Bone distraction devices are already used to treat certain conditions such as a birth defect called craniosynostosis, in which the calvarial bones fuse too early, so expanding this technique to promote bone regeneration could be a future focus of clinical trials.