Study of Differentiation Potential of the Dedifferentiated Chondrocytes From Rat Articular Cartilage into Skeletal Cell Lineages

Purpose: Dedifferentiation of the chondrocyte from rat articular cartilage with multiple subcultures and study of the redifferentiation potential of the cells into bone, cartilage and fat cell lineages. Materials and Methods: In this experimental study, chondrocytes from rat articular cartilage were isolated and expanded through several successive subcultures during which the expression levels of cartilage-specific genes including aggreacan and type II collagen were measured by using real-time PCR to determine the cell dedifferentiation (the time in which cartilage genes ceased their expression). Furthermore, during the culture period, the chondrocyte was examined morphologically by scanning electron microscopy (SEM). At the end, the dedifferentiated cells were subjected to osteogenic, adipogenic and chondrogenic culture condition to investigate whether or not they are able to redifferentaite into specialized progenies. Differentiation state was examined by specific staining and RT-PCR analysis. Results: Based on the findings by real time PCR, the expression levels of the both studied genes were high at passage 2 and dramatically decreased at passage 4. Aggreacan expression ceased at passage 10 and collagen II stopped expressing at passage 6. SEM images indicated the flattened morphology of the cells at early passages and the fibroblastic appearance at late passages. Differentiation examination revealed that the dedifferentiated cells were readily differentiated into bone, adipose and cartilage cell lineages. Conclusion: Considering all aspects together, this concluded that articular chondrocyte gradually lost their differentiated state during the long-term culture and changed into multipotent cells capable of differentiating into skeletal cell lineages.