Novel technology for bonding the engineered cartilage constructs with poly-(DL-lactic-co-glycolic acid) powder

Articular cartilage has the limited capacity for self-repair. Engineering cartilage using tissue engineering technology may provide a valuable tool for articular cartilage repair. There is limitation to manufacture the cartilage using tissue engineering technology regarding the construct dimension. We have been interested in establishing methods for engineering multi-layered cartilage to overcome the technologic limitation. Here we tried a hybrid approach combining two tissue engineered cartilages with poly-(DL-lactic-co-glycolic acid) (PLGA) powder. Rabbit articular chondrocytes (5×10 ⁶ cells/200μl) were seeded in 1.3 cm × 1.3 cm PGA scaffold and cultured for 1 week in vitro. Two PGA constructs were bridged with PLGA powder (RESOMER RG 756: Boehringer Ingelheim, Germany) and the constructs were implanted subcutaneously in the dorsum of athymic mice immediately for in vivo studies. The migration potential of the chondrocytes in engineered cartilage into the bridge of PLGA powder was observed by labeling of chondrocytes with DiI (dialkylcarbocyanine: D-282, Molecular Probes, USA). Adhesiveness of tissue engineered cartilages without any shrinkage was examined after 1 and 4 weeks using histological analysis. The cartilaginous exatracellular matrices were homogeneously distributed in both PGA scaffold and PLGA powder. Fluorescence microscopy of frozen sections of the regenerated tissue revealed that the majority of cells in the bridge of PLGA powder were derived from the DiI-labeled implanted chondrocytes. From these results, we conclude that the bonding method with PLGA appears a promising approach for manufacturing large dimension of engineered cartilage.