Tissue Cell. 2026 Feb 14. pii: S0040-8166(26)00086-8. [Epub ahead of print]100
103394
OBJECTIVE: While M2 macrophage-mediated immunoregulation is critical for bone regeneration, the role of migrasomes-a newly identified organelle-remains unexplored. This study aims to investigate the effect of M2 macrophage-derived migrasomes on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs).
METHODS: Macrophages were polarized to the M2 phenotype using IL-4. Migrasomes were subsequently isolated and characterized by electron microscopy and Western blotting (WB).In vivo, murine femoral fracture models treated with 100 μg/mL M2 macrophage-derived migrasomes were analyzed for fracture healing via X-ray, microcomputed tomography (microCT), and immunofluorescence.In vitro, bone marrow mesenchymal stem cells (BMSCs) were co-cultured with 60 ng/mL migrasomes. Cell migration was assessed by wound healing assay at 24 h; expression of RUNX2, ALP, OCN, and Bmp-2 was detected via quantitative real-time polymerase chain reaction (qRT-PCR) and WB at 72 h; osteogenic activity was evaluated by ALP and alizarin red S (ARS) staining at 14 and 21 days, respectively.
RESULTS: Increased Arg-1 and CD206 expression confirmed successful induction of M2 macrophages (P < 0.01, P < 0.0001). Transmission electron microscopy and Western blotting (WB) verified successful isolation and purification of M2 macrophage-derived migrasomes. X-ray and microcomputed tomography analyses demonstrated that migrasomes treatment significantly enhanced fracture healing. qRT-PCR showed migrasomes effectively upregulated mRNA levels of BMP-2, RUNX2, ALP, and OCN in BMSCs (P < 0.05, P < 0.01); WB revealed elevated protein levels of osteogenic markers (BMP-2, RUNX2, ALP) in the M2 migrasomes-treated group (P < 0.05).
CONCLUSION: M2 macrophage-derived migrasomes promote fracture healing by inducing osteogenic differentiation of BMSCs.
Keywords: Bone marrow mesenchymal stem cells; Fracture healing; M2 macrophages; Migrasomes; Osteogenic differentiation