Effects of transforming growth factor-ß subtypes on in vitro cartilage production and mineralization of human bone marrow stromal-derived mesenchymal stem cells

Human bone marrow stromal-derived mesenchymal stem cells (hBMSCs) will differentiate into chondrocytes in response to defined chondrogenic medium containing transforming growth factor-beta (TGF beta). Results in the literature suggest that the three mammalian subtypes of TGF beta (TGF beta 1, TGF beta 2 and TGF beta 3) provoke certain subtype-specific activities. Therefore, the aim of our study was to investigate whether the TGF beta subtypes affect chondrogenic differentiation of in vitro cultured hBMSCs differently. HBMSC pellets were cultured for 5 weeks in chondrogenic media containing either 2.5, 10 or 25 ng/ml of TGF beta 1, TGF beta 2 or TGF beta 3. All TGF beta subtypes showed a comparable dose-response curve, with significantly less cartilage when 2.5 ng/ml was used and no differences between 10 and 25 ng/ml. Four donors with variable chondrogenic capacity were used to evaluate the effect of 10 ng/ml of either TGF beta subtype on cartilage formation. No significant TGF beta subtype-dependent differences were observed in the total amount of collagen or glycosaminoglycans. Cells from a donor with low chondrogenic capacity performed equally badly with all TGF beta subtypes, while a good donor overall performed well. After addition of beta-glycerophosphate during the last 2 weeks of culture, the expression of hypertrophy markers was analysed and mineralization was demonstrated by alkaline phosphatase activity and alizarin red staining. No significant TGF beta subtype-dependent differences were observed in expression collagen type X or VEGF secretion. Nevertheless, pellets cultured with TGF beta 1 had significantly less mineralization than pellets cultured with TGF beta 3. In conclusion, this study suggests that TGF beta subtypes do affect terminal differentiation of in vitro cultured hBMSCs differently. Copyright (C) 2011 John Wiley & Sons, Ltd.