Effects of Transforming Growth Factor β1 and Dexamethasone on the Growth and Chondrogenic Differentiation of Adipose-Derived Stromal Cells

The effects of soluble mediators and medium supplements commonly used to induce chondrogenic differentiation in different cell culture systems were investigated to define their dose-response profiles and potentially synergistic effects on the chondrogenic differentiation of adipose-derived adult stromal (ADAS) cells. Human ADAS cells were suspended within alginate beads and cultured in basal medium with insulin, transferrin, and selenious acid (ITS+) or fetal bovine serum (FBS) and treated with different doses and combinations of TGF-β1 (0, 1, and 10 ng/mL) and dexamethasone (0, 10, and 100 nM). Cell growth and chondrogenic differentiation were assessed by measuring DNA content, protein and proteoglycan synthesis rates, and proteoglycan accumulation. The combination of ITS+ and TGF-β1 significantly increased cell proliferation. Protein synthesis rates were increased by TGF-β1 and dexamethasone in the presence of ITS+ or FBS. While TGF-β1 significantly increased proteoglycan synthesis and accumulation by 1.5- to 2-fold in the presence of FBS, such effects were suppressed by dexamethasone. In summary, the combination of TGF-β1 and ITS+ stimulated cell growth and synthesis of proteins and proteoglycans by human ADAS cells. The addition of dexamethasone appeared to amplify protein synthesis but had suppressive effects on proteoglycan synthesis and accumulation.