RESUMEN
CONTEXT: Psoralen, an active ingredient from Fructus Psoraleae (FP), is used in Traditional Chinese Medicine (TCM) to treat bone diseases. However, the effect of psoralen on cartilage is unknown. OBJECTIVE: To investigate the effects of psoralen on chondrocytes isolated from rats. MATERIALS AND METHODS: Chondrocytes were treated with different concentrations of psoralen (1, 10, and 100 µM) in vitro at 3-d and 9-d intervals. MTS assay, Alcian blue colorimetry, western blotting, and qRT-PCR, respectively, were used to evaluate the effects of psoralen on cell viability, glycosaminoglycan (GAG) synthesis, collagen synthesis, and cartilage-specific gene expression. RESULTS: Psoralen dosages of 1-10 µM exhibited low cytotoxicity toward chondrocytes. However, a dosage of 100 µM suppressed the proliferation of chondrocytes. Different concentrations of psoralen treatments on chondrocytes revealed that GAG and Type II collagen synthesis increased, especially at 100 µM, by 0.39-fold and 0.48-fold, respectively, on day 3, and by 0.51-fold and 0.56-fold, respectively, on day 9. Similarly, gene expression of Type II collagen, aggrecan, and SOX-9 were all up-regulated on days 3 and 9, particularly aggrecan which increased significantly by 9.37-fold and 7.32-fold at 100 µM. Additionally, Type I collagen was inhibited both in gene expression and in protein synthesis. CONCLUSION: The results showed that psoralen promotes cartilaginous extracellular matrix (ECM) synthesis, as well as increased cartilaginous gene expression, and it may be a useful bioactive component for activating the cartilaginous cellular functions of chondrocytes.