[Effect of collagen type II on redifferentiation of dedifferentiated rabbit chondrocytes].

Objective: Collagen type II is a characteristic molecular of chondrocyte. With continuous subculture of chondrocytes, they progressively lose the ability to express collagen type II. To observe the effect of collagen type II on redifferentiation of dedifferentiated rabbit chondrocytes so as to lay a experimental foundation for use of chondrocytes in cartilage tissue engineering.
Methods: Cartilage was harvested under sterile conditions from tibio-femoral joints of 7-month-old New Zealand white rabbit. The rabbit articular chondrocytes were subcultured in vitro to the 7th generation (named P1-P7). Dedifferentiated rabbit chondrocytes were chosen by RT-PCR, real-time PCR, and 1, 9-dimethylmethylene blue (DMMB) assay. Then dedifferentiated rabbit chondrocytes were treated with various concentrations (0, 0.5%, 1.0%, and 1.5%) of exogenous collagen type II. The redifferentiation of dedifferentiated chondrocytes was measured by RT-PCR and real-time PCR, and the glycosaminoglycan content was determined by DMMB assay.
Results: The glycosaminoglycan content of P1-P7 chondrocytes were (12.20 +/- 0.17), (11.20 +/- 0.24), (11.18 +/- 0.16), (10.89 +/- 0.50), (8.73 +/- 0.19), (9.39 +/- 0.32), and (8.18 +/- 0.20) microg, respectively, showing no significant difference (P > 0.05) among P2, P3, and P4, and showing significant differences (P < 0.05) among other generations. The mRNA of collagen type I, collagen type II, and aggrecan expressed at P4-P7, showing no significant difference in the mRNA expression of collagen type I (P > 0.05) and significant differences in the mRNA expressions of collagen type II and aggrecan (P < 0.05) among P4-P7. The glycosaminoglycan content at concentrations of 0, 0.5%, 1.0%, and 1.5% were (8.20 +/- 0.16), (14.61 +/- 0.33), (13.93 +/- 0.25), and (19.59 +/- 0.46) microg, showing significant differences among different concentrations (P < 0.05). With exogenous collagen type II concentrations increased, the mRNA expressions of collagen type II and aggrecan gene were up-regulated gradually, but collagen type I gene was down-regulated, showing significant differences (P < 0.05).
Conclusion: Collagen type II can promote redifferentiation and activation of dedifferentiated rabbit chondrocytes.