Proteoglycan labeling using dissociated cells of ten isolated CNC explants, which was adapted in consideration of the low number of available cells, was performed by changing the culture medium with a fresh medium that contained 2 mCi [35S]sulfate/ml and 10 µM sodium sulfate, and cultivating the cells for 24 h at 17°C. The culture medium was removed, and the cells were washed and solubilized with the urea-containing buffer as described above, followed by anion-exchange purification and HS degradation as described above. The CS/DS PGs were re-isolated by anion-exchange purification and desalted. Lyase treatment was performed as described above.
