Matrix gene expression is altered in organ culture model of disc degeneration. Real-time reverse transcription-polymerase chain reaction analysis of aggrecan (AGG) and fibromodulin after treatment. There is a significant downregulation in expression of AGG and fibromodulin (Fmod) mRNA in (A) nucleus pulposus (NP) and (B) annulus fibrosus (AF) tissues of treated discs. Results are shown as the mean ± standard error for three independent experiments. *P <0.05. (C) Presence of AGG fragments as analyzed by Western blotting in NP and AF tissue lysates after 3 days in culture. Arrows indicate the presence of additional AGG fragments recognized by anti-ARGxx antibody in the treated tissues. Representative findings of two independent experiments (n = 6 discs/group per experiment) are shown. Ctr., control group; Exp, experimental group.