Regeneration of cartilage tissue by combination of canine chondrocyte and a hybrid mesh scaffold

Canine chondrocytes isolated from articular cartilage were cultured in a PLGA-collagen hybrid mesh in DMEM containing 10% FBS in vitro for 10 days, and subsequently implanted subcutaneously in the dorsum of nude mouse. The formation of neo-cartilage tissue was examined. HE staining showed a spherical morphology of chondrocytes in the center of the explants and a fibroblast-like morphology in the periphery of the explants. The safranin O/fast green staining showed that the central part was positively stained for GAG while the periphery was negatively stained. The toluidine blue staining showed a similar result. The histological results demonstrated spherical chondrocytes surrounded by abundant cartilaginous matrices in the center of the explants. The fibro-tissue in the periphery became denser and the central cartilage tissue became thinner as the implantation period increased, suggesting the effects such as invasion of host fibroblasts and diffusion of soluble factors on the degeneration of newly formed cartilage tissue. Gene expression study using reverse transcription-polymerase chain reaction (RT-PCR) demonstrated that the expressions of type II collagen and aggrecan were detected and up-regulated, while that for type I collagen was down-regulated when the cells were cultured in the hybrid mesh. These results suggest the formation of articular cartilage in the subcutaneous dorsum of nude mouse.