CELL DEATH BY NECROSIS AND APOPTOSIS DURING THE CULTURE OF COMMERCIALLY IMPORTANT CELL LINES

The levels of necrosis and apoptosis were quantified in CHO, SF9 insect cells, and murine plasmacytoma and hybridoma cells by acridine orange staining and fluorescence microscopy. This technique enabled the visualisation of a classic morphological feature of apoptotic cells, the presence of condensed and/or fragmented chromatin. DNA gel electrophoresis was also employed to show an additional characteristic of the process, the endonuclease mediated fragmentation of DNA into multiples of 180 base pairs. Necrosis was found to be the dominant mechanism of cell death in the cultures of CHO and SF9. However, significant levels of apoptosis were found in the plasmacytoma and hybridoma cell lines. Around 81% of dead hybridoma cells were apoptotic by day 5 of a batch culture. By day 4 of the plasmacytoma batch culture the level of apoptosis was approximately 60% of dead cells.