Figure 4.

TGF-β1 accelerates both formation and degeneration of mandibular condylar cartilages in the absence of Bgn and Fmod. A: TGF-β1 induces proliferation of MCCs. BrdU ELISA was used to measure proliferation of MCCs treated with vehicle or TGF-β1. Data are mean ± SEM of 6 wells. *P < 0.005 vehicle versus TGF-β1. B: TGF-β1 induces the expression of chondrogenic-related genes in the MCCs. Quantitative real-time RT-PCR analysis compared the expression levels of chondrogenic-related genes using total RNA isolated from MCCs treated with vehicle or TGF-β1. Gene expression was normalized to the housekeeping gene S29. The expression of genes in MCCs treated with vehicle was relative to that in MCCs treated with TGF-β1. Data are mean ± SEM of 2 experiments. *P < 0.02, **P < 0.002 vehicle versus TGF-β1. C: TGF-β1 accelerates loss of aggrecan content in mandibular condyle explants. Whole mandibles were isolated from wild-type and Bgn^−/0 Fmod^−/− mice and explants were cultured for 48 hours with vehicle or 2 ng/ml TGF-β1. Comparable histological sections from explants were stained with H&E. Aggrecan and type II collagen expression was examined by immunohistochemistry. Rabbit IgG and mouse IgG₁ were used under the same conditions as negative controls, respectively. Dashed yellow lines divide the condyle into articular zone (A), mature zone (M) and hypertrophic zone (H). Black double-ended arrows indicate extent of articular and mature zones. Black square indicates chondrocyte cluster. Scale bar = 50 μm.