Fig 2: BMSC-Exo extracted from MOP-treated GIOP rats inhibit osteoclast differentiation of BMMs induced by RANKL. (A) The BMSC-Exo from GIOP rats after different doses of MOP treatment were extracted, termed L-MOP-Exo, M-MOP-Exo and H-MOP-Exo, respectively; the portion of multinucleated cells in the Exo-pre-treated BMMs followed by RANKL induction determined by TRAP staining; (B) mRNA expression of CTSK and MMP9 in BMMs examined by RT-qPCR; (C) intensity of CTSK and MMP9 staining in BMMs examined by immunofluorescence staining; (D) proliferation activity of BMMs examined by the CCK-8 method; (E) colony formation ability of the BMMs examined by the colony formation assay. At least three independent experiments were performed. Differences were compared by one-way ANOVA (B, D and E) or two-way ANOVA (C and D). **p < 0.01 vs. PBS-Exo.

Fig 3: Expression of OPG (A), RANKL (B), NF-?B (C) mRNA as detected by quantitative RT-PCR (x ± SD). Error bars represent standard deviations (n = 3). As compared with the control group, ## p < 0.05 indicates that mRNA expression levels of OPG and NF-?B decreased and the mRNA expression level of RANKL increased in the arthritis model (AA) group. As compared with the AA group, ** p < 0.01 indicates that groups of treated arthritic rats exhibited increased expression of OPG mRNA, decreased expression of RANKL mRNA, and significant inhibition of NF-?B signaling pathway activity.

Fig 4: Effects of different treatments on levels of serum cytokines TNF-α (A), IL-1β (B), PGE2 (C), and on levels of signaling pathway proteins RANKL (D), OPG (E) and RANKL/OPG (F) in arthritic rats (x ± SD). Error bars represent standard deviations (n = 6). As compared with the control group, # p < 0.05 and ## p < 0.01 indicate that serum cytokine levels of the untreated arthritis model (AA) group were significantly different from corresponding control group levels. As compared with the untreated arthritis model (AA) group: * p < 0.05 and ** p < 0.01 indicated significant reduction in serum cytokine levels in the treated arthritis model group.

Fig 5: GIOP-Exo treatment promotes osteoclast differentiation and growth of RANKL-induced BMMs. (A) The portion of multinucleated cells in BMMs after RANKL treatment determined by TRAP staining; (B) uptake of PKH67-labelled Exo by BMMs observed under the fluorescence microscope; (C) the portion of multinucleated cells in Exo-pre-treated BMMs followed by RANKL induction determined by TRAP staining; (D) mRNA expression of CTSK and MMP9 in BMMs after Exo treatment examined by RT-qPCR; (E) intensity of CTSK and MMP9 staining in BMMs after Exo treatment examined by immunofluorescence staining; (F) proliferation activity of BMMs examined by the CCK-8 method; (G) colony formation ability of the BMMs examined by the colony formation assay. At least three independent experiments were performed. Differences were compared by the unpaired t-test (A), one-way ANOVA (C, F and G), and two-way ANOVA (D and E). **p < 0.01.