Chondrogenic phenotype of articular chondrocytes in monoculture and co-culture with mesenchymal stem cells in flow perfusion.

This work investigated the effect of flow perfusion bioreactor culture with and without transforming growth factor-β3 (TGF-β3) supplementation on the proliferation, extracellular matrix (ECM) production, and chondrogenic gene expression of chondrocytes both in monoculture and in co-culture with bone marrow-derived mesenchymal stem cells (MSCs). Both cell populations were cultured on electrospun poly(ɛ-caprolactone) scaffolds for 2 weeks in static or flow perfusion culture with and without TGF-β3. Overall, it was observed that without growth factors, flow perfusion culture resulted in increased cell proliferation and ECM with a more cartilage-like composition. While with TGF-β3 induction, flow perfusion constructs generally had lower chondrogenic gene expression than the corresponding static cultures, the growth factor still had an inductive effect on the cells with enhanced gene expression compared with the corresponding noninduced cultures. In addition, while flow perfusion cultures generally had reduced overall ECM content, the ECM distribution was more homogenous compared with the corresponding static cultures. These results are significant in that they indicate that while flow perfusion culture has some beneficial effects on the chondrogenic phenotype of articular chondrocytes, flow perfusion alone is not sufficient to maintain the chondrogenic phenotype of chondrocytes in either monoculture or co-culture, thus demonstrating the advantages of using exogenously added growth factors in flow perfusion culture. Furthermore, the results demonstrate the advantages of flow perfusion culture for the creation of large tissue engineered constructs and the potential of co-cultures of articular chondrocytes and MSCs to be used in flow perfusion culture.