Fig. 3: The macrophage population is significantly increased in the quadriceps of OA joints.

a, Flow cytometry analysis strategy for quantifying the abundance of living stromal cells in the quadriceps of mice at D4, D12, S4 and S12. b–e, The proportions of satellite cells (b), FAPs (c), endothelial cells (d) and immune cells (e) within the stromal cell population of quadriceps were determined. Each tested sample was a pool of 3 individual mice (n = 5). f, Flow cytometry analysis strategy for quantifying the abundance of living CD45⁺ stromal cells in the quadriceps of mice at S4, D4, S12 and D12. g,h, The proportions of T cells (g) and B cells (h) within the CD45⁺ stromal cell population of quadriceps were determined. Each tested sample was a pool of 3 individual mice (n = 7 sham, n = 6 DMM). i, Macrophages within the CD45⁺ stromal cell population of quadriceps were quantified (n = 6). j, Immunofluorescence staining and the abundance determinations of F4/80⁺ cells in the quadriceps of OA mice (n = 6). k, Immunofluorescence staining and quantitative analysis of CD68⁺ cells in the quadriceps of patients with OA and control subjects (n = 6 control, n = 10 OA). l, Experimental design. Lyz2;ROSA-tdTomato mice were used as a tracer for in vivo imaging of myeloid cells using two-photon microscopy (2PM). m, Representative images and quantitative results of 2PM-captured cells in the quadriceps of OA mice (n = 4). Data are presented as mean ± s.e.m. unless otherwise noted; all statistical tests were two-sided unless otherwise noted; and n represents biological replicates unless otherwise noted. Student’s t-test (b–d,e (12 weeks), g–m). Mann–Whitney U-test (e (4 weeks)). Median (25% IQR, 75% IQR; e (4 weeks)). FSC-A, forward scatter area; FSC-H, forward scatter height; SSC-A, side scatter area; Mø, macrophage; QF, quadriceps.