Redifferentiation of dedifferentiated bovine chondrocytes when cultured in vitro in a PLGA–collagen hybrid mesh

Bovine articular chondrocytes dedifferentiated and lost their ability to express articular cartilage-specific extracellular matrices such as type II collagen and aggrecan when cultured in a culture flask during in vitro multiplication. A poly(DL-lactic-co-glycolic acid) (PLGA)-collagen hybrid mesh was prepared and used to redifferentiate the dedifferentiated cells. The two passaged dedifferentiated chondrocytes were seeded in a PLGA-collagen hybrid mesh and cultured in vitro in Dulbecco's modified Eagle's medium containing 10% fetal bovine serum. The cells adhered to the hybrid mesh, distributed evenly, and proliferated to fill the spaces in the scaffold. The gene expression of type I collagen, type II collagen, and aggrecan was analyzed after the cells were cultured in the hybrid mesh for 2-12 weeks. The expression of the gene encoding type I collagen was downregulated, whereas those of type II collagen and aggrecan were upregulated. Histological examination by hematoxylin-eosin and safranin O/fast green staining indicates that the cells regained their original round morphology. In addition, a homogeneous distribution of articular cartilage extracellular matrices was detected around the cells. These results suggest redifferentiation of the differentiated chondrocytes in the hybrid mesh. The hybrid mesh, which facilitated the redifferentiation of the dedifferentiated multiplied chondrocytes, would be an effective scaffold for the assembly of cells to regenerate three-dimensional cartilaginous tissue.