Figure 5. BMSC exosomes reduced synovial macrophage infiltration, induced changes in M1/M2 subsets, and reduced inflammation in the rat model. (A) Representative images of HE staining in synovial tissue. Scale bar: 50 μm. (B) Quantification of synovitis scores in synovial tissue. (C) and (D) Immunohistochemistry and analysis of Arg1 in synovial tissue, respectively. Scale bar: 50 μm. (E) and (F) Immunofluorescence and analysis of F4/80 and iNOS, respectively, in synovial tissue. Scale bar: 50 μm. (G–J) Determination of the cytokines, IL-1β, IL-6, TNF-α, and IL-10 in synovial fluid from each test group. * p < 0.05 compared to the Sham group; # p < 0.05 compared to the PBS group.