Psoralen activates cartilaginous cellular functions of rat chondrocytes in vitro

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 mu M) 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 mu M exhibited low cytotoxicity toward chondrocytes. However, a dosage of 100 mu M suppressed the proliferation of chondrocytes. Different concentrations of psoralen treatments on chondrocytes revealed that GAG and Type II collagen synthesis increased, especially at 100 mu M, 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 mM. 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.