Enhanced chondrogenesis in a coculture system with genetically manipulated dedifferentiated chondrocytes and ATDC5 cells

Articular cartilage repair after injury is a great challenge worldwide due to its nerveless and avascular features. Tissue engineering is proposed as a promising alternative for cartilage regeneration. In this study, an adenoviral vector carrying the transforming growth factor‐β3 (TGF‐β3) gene was constructed and introduced into dedifferentiated chondrocytes, which were then cocultured with ATDC5 cells in an alginate hydrogel system. The results showed that the experimental groups exhibited better cell viability and higher levels of cartilage‐related genes than the control groups. In this coculture system, the chondrogenic differentiation of ATDC5 cells was effectively induced by TGF‐β3 and other latent cytokines that were produced by the transfected chondrocytes. Thus, this method can avoid the degradation of exogenous TGF‐β3, and it can protect ATDC5 cells during virus transfection to maintain cell viability and chondrogenic differentiation capability. Taken together, this study provides fresh insights for applying this genetically manipulated coculture system to cartilage repair in the future. In the coculture system, the transfected chondrocytes could provide local and overexpressed TGF‐β3 to MSCs and stimulate MSCs to differentiate into chondrocytes. Through the optimization of the coculture system, the supply of TGF‐β3 can be terminated in time by chondrocyte apoptosis while MSCs can fully complete chondrocytic differentiation but avoid entering the fate of apoptosis caused by TGF‐β3 overexpression.