Measurement of bead size.

(A) After 21 days of culture, the size of the TGF-β1-transduced chondrocyte-atelocollagen mixture beads (upper) under non-differentiation and (lower) and chondrogenic differentiation conditions was compared. (B) The size of the TGF-β1-transduced chondrocyte-atelocollagen mixture beads under chondrogenic differentiation conditions was significantly reduced. Analysis of gene expression. Real-time quantitative polymerase chain reaction analysis of (C) type II collagen, (D) aggrecan, and (E) SOX9 expression of TGF-β1-transduced chondrocytes cultured for 21 days under non-differentiation and chondrogenic differentiation conditions, and TGF-β1-transduced chondrocytes-atelocollagen cultured for 21 days under chondrogenic differentiation conditions (* P <0.05, ** P <0.01, *** P <0.001). Histological images of the TGF-β1-transduced chondrocyte-atelocollagen mixture: (F) Hematoxylin-eosin, (G) toluidine blue, (H) Alcian blue pH 2.5, and (I) type II collagen. (F-I, × 400).