Wnt Inhibitors Promote Chondrogenesis from Adipose Stem Cells

This study was performed to investigate the effect of Wnt inhibitors on chondrogenesis from adipose stem cells (ASCs). Two Wnt antagonists, secreted frizzled-related protein (sFRP)-1 and Dickkopf-related protein (DKK)-1, were treated on passage 3 ASCs in pellet culture. Cell viability was measured at various concentrations (2, 10, 50nM) of each inhibitor by MIT assay, and the inhibition of beta-catenin was examined by western blot analysis. Chondrogenic differentiation was analyzed by glycosaminoglycan (GAG) assay and Safranin-O staining, and the gene and protein expression of chondrogenic markers by quantitative RT-PCR and Western blot analysis. The cell viability of ASCs was not significantly affected in the concentration of Wnt inhibitors we used. The expression of beta-catenin decreased with the treatment of either inhibitor. There was a significant increase of proteoglycan, and the type II collagen gene and protein expression in ASCs treated with either sFRP-1 or DKK-1. The gene expression of type I collagen decreases while that of type X collagen increased with the treatment of either sFRP-1 or DKK-1. The overall results suggest that the Wnt inhibitiors enhanced chondrogenesis from ASCs.