Fig. 3

Leptin inhibited chondrocyte proliferation and stimulated apoptosis in VGP. a Colorimetric based cell proliferation assay (CCK-8 assay) for primary TGP and VGP chondrocytes that had been treated with recombinant leptin for 24 h or 48 h at different concentrations (0, 10, 50, 100, and 1000 ng/mL). Right panel: cyclin D1 mRNA level was measured by real time quantitative PCR for the leptin-treated cells using GAPDH as the reference gene. (* p < 0.05, Student’s t-test, n = 3). b Cell cycle analysis of the TGP and VGP chondrocytes treated with different concentrations of leptin (0, 10, and 100 ng/mL). Right panel: quantification of the proliferation index that is defined by the faction of S and G2/M cells in the total cells (%). (* p < 0.05, Student’s t-test, n = 3). c Flow cytometry analysis of apoptosis for the primary TGP and VGP chondrocytes treated with 0, 10, and 100 ng/mL of leptin. Right panel: quantification of the apoptotic cell populations (A2) from the flow cytometry analysis of apoptosis (* p < 0.05, Student’s t-test, n = 3)