Effects of the media condition and CM or bi-layered co-culture on gene expression. Gene expression of (A) aggrecan (Agg), (B) collagen type II (COL2), (C) collagen type I (COL1), and (D) collagen type X (COLX) in control culture (C, OACs, A, ADSC), CM, or bi-layered co-culture (Bi) after 21 days with or without TGF-β3 supplementation. Fold changes relative to OAC control without TGF-β supplementation. Bi-layered co-culture group included both OACs and ADSCs (equal initial cell number). Data presented as mean±standard deviation (SD, n=3 samples/group); * represents significance versus−TGF-β control and ^ represents significance versus−CM control of the same cell type; +and # represent significance of the bi-layered co-culture group versus OAC and ADSC under the same media condition, respectively; *p<0.05, **p<0.01, and ***p<0.001.