Fig. 6. Relative gene expression levels of MMPs and TIMPs. Filled bars: relative gene expression levels of TIMP-1 (n=5), TIMP-2 (n=5), MMP-1 (n=5), MMP-3 (n=4) and MT1-MMP (n=5) in cocultured chondrocytes normalized to monocultured chondrocytes. Open bar: relative gene-expression level of MMP-9 (n=4) in cocultured monocytes normalized to monocultured monocytes. RNA was extracted separately from chondrocyte and monocyte layers after coculturing. Expression levels of gene sequences of interest, normalized to an internal standard (GAPDH) were calculated relative to a calibrator sample. These calibrator samples constitute either chondrocytes cultured without monocytes (TIMP-1, TIMP-2, MMP-1, MMP-3, MT1-MMP) or monocytes cultured without chondrocytes (MMP-9) set at 1.0, represented by the x-graph lines. Standard deviation was calculated with Microsoft Excel from mean values of total number of experiments, each done in triplicate.
