Figure 4. Analysis of the effect of XT-I knockdown on GAG synthesis in chondrocytes and cartilage explants.

Cells were transfected with XT-I shRNA, or control shRNA or left untreated and then examined for mRNA expression (A) and GAG synthesis (B). Total RNA was isolated from cells of each group at 72 h posttransfection and XT-I expression level was determined by qPCR analysis. XT-I mRNA levels are represented as a ratio relative to those in negative controls or untreated controls. GAG synthesis was studied by ³⁵S-sulfate incorporation. (C) Cartilage explants from normal region of human femoral condyle of three patients were transfected with XT-I shRNA or control shRNA and then GAG synthesis was analyzed by ³⁵S-sulfate incorporation. Measurements were normalized to control shRNA. Data represent the mean ± SD of 3 independent observations for each group. **,*Significantly (P<0.01, P<0.05, respectively) lower than control shRNA.