Is continuous treatment with transforming growth factor-beta necessary to induce chondrogenic differentiation in mesenchymal stem cells?

This study was conducted to determine whether short-term administration of transforming growth factor (TGF)-β would be as effective for inducing chondrogenesis in human mesenchymal stem cells (hMSCs) as continuous treatment. Four groups of hMSCs were cultured in a monolayer for 3 days followed by a pellet culture for 3 weeks under various conditions: group A, the control group, no growth factors treated; group B, 5 ng/ml of TGF-β₂ was treated for 3 days in monolayer culture; group C, 5 ng/ml of TGF-β₂ was treated for 3 days in a monolayer culture and the initial 3 days of pellet culture; group D, 5 ng/ml of TGF-β₂ was treated for 3 days in a monolayer culture and the initial 10 days of pellet culture; group E, 5 ng/ml of TGF-β₂ was continuously treated throughout the culture period. Glycosaminoglycan contents significantly increased in group E only. Real-time PCR indicated that expression of Sox-9, type II collagen, type II procollagen B and type X collagen increased with longer duration of TGF-β₂ treatment. The histological findings showed that longer duration of TGF-β₂ treatment led to significantly better quality of chondrogenesis. This study demonstrated that longer duration of TGF-β treatment is necessary for effective chondrogenesis in hMSCs from bone marrow.