M2-exosomes promote macrophage reprogramming and osteogenesis. (A) qRT-PCR analysis of the mRNA levels of CD206, Arg-1, IL-10, and CD163 in macrophages from M2-exosomes-treated groups. n = 3. (B) Western blot experiments show the protein level of the M1 and M2 macrophage markers, including CD86, CD206, and Arg-1. (C) Immunofluorescence analysis of the M1 and M2 macrophages markers, including iNOS and CD206. Scale bar: 50 μm. (D) M2 macrophages were co-located using F4/80 and CD206 and analyzed by FCM. (E) Representative images of ALP staining of BMSCs after 7 days of continuous induction of RM2 macrophages supernatant. Scale bars: 1000 μm. (F) ALP staining of BMSCs corresponding quantitative analysis, n = 3. (G) Representative picture of Alizarin Red S analysis of BMSCs cultured with RM2 macrophage supernatant for two weeks. Scale bars: 1000 μm. (H) ARS staining of BMSCs corresponding quantitative analysis, n = 3. (I–J) qRT-PCR analysis of mRNA levels of BMP-2, Runx2, Osterix and OCN in BMSCs of RM2 macrophages supernatant treatment group. ***P < 0.001.