L proline

Four groups were established as follows: (1) hADSCs grown in growth medium alone (GM group); (2) hADSCs treated with chondrogenic differentiation medium (CH group); (3) hADSCs treated with chondrogenic differentiation medium and 1 μg/mL etanercept (CHE group); and (4) hADSCs treated with chondrogenic differentiation medium and 10 μg/mL infliximab (CH+Inf group).
The chondrogenic differentiation medium was composed of basic high-glucose DMEM (1X), 5% FBS, 1% penicillin/streptomycin, 1% insulin-transferrin-selenium-sodium-pyruvate solution (ITS-A; Gibco), 100 nmol/L dexamethasone (Theremofisher; Massachusetts, USA) 50 μg/mL, 40 mg/mL L-proline (Macklin; Shanghai, China), and 10 ng/mL TGF-β3 (Peprotech; NJ, United States). For the CHE and CH+Inf groups, 1 μg/mL etanercept (MCE, NJ, United States) and 10 μg/mL infliximab (MCE) were added to the chondrogenic differentiation medium to inhibit the bioactivity of TNF-α. For every group, the GM was changed every other day, and all the treatments were applied when the cells reached confluence in the culture dishes.
The cells were harvested and assessed on days 7, 14, 21, and 28. The results presented are mainly those of Western blotting analysis, enzyme linked immunosorbent assay (ELISA), fluorescence imaging, and toluidine blue staining.