Circulating MiRNA-21-enriched extracellular vesicles promote bone remodeling in traumatic brain injury patients

Bone fracture: faster healing after traumatic brain injury Extracellular vesicles enriched with a particular microRNA released following traumatic brain injury (TBI) help fractures heal faster and could inform treatments for skeletal disorders. Patients with TBI and associated fractures experience shorter fracture recovery times than patients with fractures only, but precisely why is unclear. Ze Lin at Huazhong University of Science and Technology, Wuhan, China, and co-workers examined molecules released during recovery in samples taken from patients with TBI and fractures, those with fractures only, and mouse models with femur fractures. They found that exosomes (extracellular vesicles that transport metabolites including microRNA) released following TBI are enriched with miRNA-21-5 p, which enhances differentiation of bone-forming cells and bone repair. No miRNA-21-5 p enrichment occurred in patients with fractures only. Knocking out exosomal miRNA-21-5 p impaired bone repair in mice, while injecting exosomes from TBI patients boosted bone formation.