Effect of Longan polysaccharides on proliferation and phenotype maintenance in rabbit articular chondrocytes in vitro

For autologous chondrocyte implantation (ACI) to restore cartilage defect, limited cell numbers and dedifferentiation of chondrocytes are the major difficulties. An alternative is the use of growth factors, but the high cost and potential tumorigenesis are the major obstacles. To ensure successful ACI therapy, it is of significance to find effective substituted pro-chondrogenic agent. Polysaccharides from plant extract have low toxicity and few undesirable side effects, which were reported to facilitate cartilage regeneration. In this study, we investigated the effect of Longan polysaccharides (LP) on rabbit articular chondrocytes through examination of the cell proliferation, morphology, viability, glycosaminoglycan synthesis and cartilage-specific gene expression. Results showed that close to the positive group which used the growth factor of TGF-β, LP could effectively promote chondrocytes growth and enhance secretion and synthesis of cartilage extracellular matrix by up-regulating expression levels of aggrecan, collagen II and sox9 compared to the negative control. Expression of collagen I gene was effectively down-regulated, demonstrating the inhibition of chondrocytes dedifferentiation by LP. Hypertrophy that might lead to chondrocyte ossification was also undetectable in LP groups. Range of 4.69-18.76 µg/ml was recommended dose of LP, among which the most profound response was observed with 9.38 μg/ml. All the evidences revealed that LP may replace the growth factors to be applied in ACI therapy. This study might provide a basis for development of a novel agent in the treatment of articular cartilage defect.