Pre-osteoblast-derived migrasomal miR-21a-5p inhibits osteoclast differentiation via the Myc/MAPK/ERK axis to alleviate osteoporosis

Osteoporosis is a progressive skeletal degenerative disease characterized by an imbalance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption. Migrasomes, a recently discovered class of migration-dependent extracellular vesicles released along the retraction fibers of migrating cells, are known to mediate intercellular communication. This study aimed to investigate the role of migrasomes in osteoporosis and elucidate the underlying regulatory mechanisms. Immunofluorescence and Western blotting were employed to evaluate changes in migrasome-associated markers in osteoporotic bone tissue. Publicly available single-cell RNA-sequencing datasets of human bone tissue were re-analyzed to identify cellular sources associated with altered migrasome signatures. Migrasomes derived from pre-osteoblasts were characterized via electron microscopy, nanoparticle tracking analysis, Western blotting, and high-throughput miRNA sequencing. Functional assays were conducted in vitro using MC3T3-E1 and RAW264.7 cells, and in vivo via tail vein injection of migrasomes or miR-21a-5p agomiR in an ovariectomy (OVX)-induced osteoporosis mouse model. Osteoblast-related migrasome markers were markedly downregulated in osteoporotic bone tissues. Exogenous supplementation with pre-osteoblast-derived migrasomes significantly alleviated OVX-induced bone loss. In vitro mechanistic experiments demonstrated that migrasomes inhibited osteoclast differentiation by delivering miR-21a-5p, which targets Myc and blocks the MAPK/ERK signaling axis, without directly affecting osteoblast differentiation. In vivo, treatment with either migrasomes or the miR-21a-5p agomiR significantly improved bone microarchitecture in OVX mice. Our findings reveal a previously unrecognized osteoblast–osteoclast communication axis mediated by migrasome-associated miRNAs and provide preclinical proof-of-concept for miR-21a-5p as a potential therapeutic target for osteoporosis.