ascorbate

Varied exogenous chondrogenic factors (CFs) are implicated in promoting differentiation of stem cells along a chondrocyte lineage in the field of regenerative tissue engineering for articular cartilage repair. The effects of dexamethasone, transforming growth factor β3 (TGF-β3), ascorbate, and their combinations, on mRNA expression in micromass-cultured human adipose derived stem cells (hADSCs) were investigated as a function of time. Indices include chondrogenic, hypertrophic, angiogenic, fibrogenic and osteogenic markers along with mechanical properties, assessed by atomic force microscopy. Early in the culture, i.e., at day three, no significant differences in mRNA expression of SOX9, aggrecan, lubricin, Col XI, Col X, vascular endothelial growth factor, Col I, and alkaline phosphatase were observed among samples treated with different CFs. However, significant differences in mRNA expression levels of pre-mentioned markers among samples treated with each CF exist when samples were supplied with the CFs for more than three days. A new indexing scheme summing expression of chondrogenic and subtracting non-chondrogenic angiogenic, fibrogenic and osteogenic marker levels shows dexamethasone is the overall leading CF among the factors and their combinations. Based on this scheme, we have projected not only the possible signaling pathways which might be affected by addition of CFs but also hypothetical indexes that may occur upon temporal variation of growth factor regimens.