Fig. 4

Irisin enhances chondrogenic differentiation of hMSCs by activating the PI3K/AKT pathway. A Protein expression levels of PI3K, p-PI3K, AKT and p-AKT were detected by western blot in controls and irisin-treated groups on 7 days. B Quantitative expression levels of PI3K, p-PI3K, AKT and p-AKT using Image J software. C The ratios of relative protein expression of p-PI3K to relative protein expression of PI3K (p-PI3K/PI3K), and p-AKT to relative protein expression of AKT (p-AKT/AKT). D The mRNA and protein expression levels of COL2A1, ACAN, and SOX9 were detected by qPCR and western blot in control, r-irisin, and r-irisin + 3MA-treated group. E The mRNA and protein expressions of COL2A1, ACAN, and SOX9 were detected by qPCR and western blot in control, irisin, and irisin + GSK690693-treated group. F Immunofluorescence of COL2A1 and SOX9 of hMSCs-induced cartilage tissues. (Magnification: × 400, scale bar: 50 μm). G Safranin O and Alcian Blue staining were performed after 7 days of differentiation in different group. (Magnification: × 200, scale bar: 100 μm). The concentration of irisin used in this figure was 100 ng/ml. *P < 0.05, **P < 0.01 compared with the control group. ^#P < 0.05, ^##P < 0.01 compared with the irisin-treated group