Purpose: This study was designed to determine whether multipled chondrocytes immersed in a new scaffold, 75:25 poly(L-lactide-epsilon-caprolactone) sponge coated with type I collagen (75-PLC scaffold), could be used to generate cartilage tissue in vivo and to evaluate the correlation between cartilage generation and the phenotype of the proliferated chondrocytes.
Materials and methods: Rat chondrocytes were suspended in 75-PLC scaffold at a density of 1 x 10 7 cells/mL after proliferation in a monolayer for 1 (P1) to 4 passages (P4) and implanted in nude mice for 4 weeks. Cells were characterized by the expression of genes encoding type II collagen, aggrecan, and type I collagen by Northern hybridization, and consequently, the newly formed tissue was evaluated histologically.
Results: The expression of aggrecan messenger RNA gradually decreased with the passaged cultures; however, the expression of type I collagen messenger RNA increased with time. The cartilage formations in all specimens were found not only in P1 chondrocytes but also in P2 chondrocytes, although when P3 chondrocytes were grafted, approximately 50% of cartilage formation was still observed up to but not beyond P4.
Conclusion: It is suggested that cartilage tissue is generated with cultured chondrocytes up to P2 but not beyond P4. Northern blot analysis is useful for the assessment of whether the cells are capable of regeneration.