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Figure S1. M- and F-MDSCs demonstrate similar in vitro stem cell characteristics. (A) The preplate technique was used to isolate M- and F-MDSCs from skeletal muscle tissue. Phase-contrast images of M- and F-MDSCs at ∼15 PDs. (B) Morphologic measurements of cell size and shape showed no statistical differences in the area, diameter, elongation, or roundness parameters of M- and F-MDSCs (median area: M-MDSCs, 345 µm² vs. F-MDSCs, 340 µm², P = 0.183; median diameter: M-MDSCs, 28 µm vs. F-MDSCs, 25 µm, P = 0.370; median elongation: M-MDSCs, 1.51 vs. F-MDSCs, 1.53, P = 0.75; median roundness: M-MDSCs, 1.38 vs. F-MDSCs, 1.48, P = 0.395). (C)With appropriate stimulation, M- and F-MDSCs expressed differentiation markers of multiple mesodermal lineages in vitro. M- and F-MDSCs underwent osteogenic differentiation, as detected by AP expression (C1), and adipogenic differentiation, as indicated by Oil Red O lipid vacuoles (C2). *, male (top) and female (bottom). The boxed area is an enlargement of the adjacent adipocytes with the red asterisk. (D) We observed no significant difference in telomere length as a result of the sex of the cells (P > 0.05). Mean fluorescence intensity (FITC) was measured by flow cytometry to provide the relative telomere length. (E) Relative telomerase activity was also similar between the M- and F-MDSCs and among the cells of different levels of population. Error bars represent SD.