Effect of sclerostin on chondrocyte metabolism. (A) Alcian blue staining and spectrophotometric quantification. Sclerostin (Scl; 20 ng/ml for 24 hours) partially restored the amount of glycosaminoglycans (GAGs) released with interleukin 1β (IL-1β; 1 ng/ml for 24 hours) (n = 13 independent experiments). Ct, Threshold cycle. Bar, 100 nm. (B) and (C) Scl rescued the gene expression of the anabolic markers (COL2A1 and ACAN), but inhibited that of catabolic markers (ADAMTS5, MMP3 and MMP13) (n = 3). (D) Western blot analysis of Scl revealed inhibition of the increased expression of Adamts-4 and matrix metalloproteinase 13 (MMP13) with IL-1β treatment (n = 3). Wild-type chondrocytes were used for all the experiments. Data are mean ± SEM. *P < 0.05 compared with control; £P < 0.05 compared with Wnt3a; #P < 0.05.