Glycosaminoglycan (GAG) content in pellets of human amnion-derived mesenchymal stromal cells and epithelial cells (hAMSCs and hAECs) and human adipose-derived stromal cells (hADSCs). (A) Alcian Blue staining for glycosaminoglycan of hAEC, mixed (hAEC + hAMSC co-culture), hAMSC, and hADSC cell pellets (blue = positive staining) cultured in chondrogenic differentiation medium at day 3 and day 7. (B) Quantitative analysis of percentage area of the cell pellet stained positive for GAG and (C) comparison of hAEC, mixed (hAEC + hAMSC co-culture), hAMSC, and hADSC cell pellet diameter cultured in differentiation medium at day 3 and 7. *Statistical differences compared with the hADSC group at the same time point (P < .05). #Statistical difference (P < .05) within each cell group compared with its respective day 3 value.