Fig. 5. The accumulation of apoptotic chondrocytes in cultures obtained from OA patients and normal donors following exposure to ROS or RNS.
Twenty four hours following exposure to increasing concentrations of xanthine oxidase or peroxynitrite, cells were washed three times with PBS and fixed with 4% paraformaldehyde. The fixed cells were washed again with PBS and stained with 1 µg/ml DAPI. Stained cells were examined by fluorescent microscopy to identify apoptotic cells. To evaluate the percentage of apoptotic cells, 6–7 fields from each experimental condition were viewed in a blinded fashion until a total of 500 cells were observed. The results were obtained from a minimum of 6 independent experiments, and the values represent the mean percentage of apoptotic cells ± SEM. * indicates a significant difference (P<0.05) in the percentage of apoptotic cells in cultures from OA patients compared to normal donors. Note the increased in apoptosis in OA chondrocytes following exposure to both genotoxins.