Intercellular communication via miR-143-containing microvesicles controls osteoblastic bone formation in vivo

Osteoblasts are the only somatic cell type with bone-forming ability. While the cellular and molecular mechanisms underlying their differentiation and function have been identified, their dynamic control in vivo is unclear. By intravital multiphoton microscopy of live bone tissues of osteoblast fluorescent reporter mice, we visualized intact mature osteoblasts in vivo and found that they actively secrete and capture extracellular microvesicles. Microvesicles from mature osteoblasts contain the microRNA miR-143-3p, which inhibits osteoblast differentiation. Osteoblast-specific deletion of miR-143 increased bone formation and miR-143-deficient microvesicles induced recovery from bone defect. In sum, we report a novel mode of intercellular communication in vivo via microRNA-containing extracellular vesicles, which controls bone homeostasis. Overall design: We performed next-generation sequencing analysis of small RNAs in total mOB-derived large EVs without filtration.