Damaged Brain Accelerates Bone Healing by Releasing Exosomes that Target Osteoprogenitors

Clinical evidence has established that concomitant traumatic brain injury accelerates bone healing, but the underlying mechanism is unclear. This study showed that after TBI, injured neurons, mainly those in the hippocampus, released osteogenic microRNA (miRNA)-enriched exosomes, which targeted osteoprogenitors in bone to stimulate bone formation. Importantly, increased fibronectin expression on exosomal surface contributed to targeting of osteoprogenitors in bone by TBI exosomes, thereby implying that modification of the exosome surface fibronectin could be used in bone-targeted drug delivery. Together, our findings have established a novel role of central regulation in bone formation and a clear link between injured neurons and osteogenitors, both in animals and clinical settings.