Figure 2

Visfatin induces NGF expression and release by chondrocytes. Human OA chondrocytes were stimulated for 24 hours with increasing concentrations of visfatin (0, 1, 2.5 and 5 μg/mL) and NGF mRNA expression (A) and release into cell supernatant (B) were measured by quantitative RT-PCR and ELISA, respectively (n = 3) Control cells released 20.4 ± 12.2 pg/mL NGF. (C) Primary cultures of mouse articular chondrocytes were stimulated for 24 hours with increasing concentration of visfatin (0, 1, 2.5, 5 and 10 μg/mL) and NGF levels were measured in conditioned media (n = 3). Inset: NGF mRNA expression was determined by quantitative RT-PCR in control cells and chondrocytes stimulated with visfatin (5 μg/mL) for 24 hours. The amount of NGF mRNA was normalized against the amount of HPRT mRNA measured in the same cDNA. (D) Mouse articular chondrocytes were incubated with or without Apo866 (10 nM) for 4 hours and then treated or not with visfatin (5 μg/mL) for 24 hours (n = 3). NGF release was determined into cell-conditioned media. *P <0.05, **P <0.01, ***P <0.001. ELISA, enzyme-linked immunosorbent assay; NGF, nerve growth factor; OA, osteoarthritis.