CRYSTAL VIOLET NUCLEI STAINING TECHNIQUE LEADS TO ANOMALOUS RESULTS IN MONITORING MAMMALIAN-CELL CULTURES

Nuclear counts determined by crystal violet staining from samples of s tationary or microcarrier cultures of hybridomas, CHO or Vero cells we re consistently and significantly higher than cell concentrations dete rmined by the trypan blue or Coulter counter methods. This difference was attributed to the presence of a significant proportion of binuclea ted cells, which are assumed to be 35% of the cell population in the s tationary phase of Vero cultures. The proportion of such cells during exponential growth was variable. However, continuous sub-culture of th ese cells induced a degree of synchrony during growth which resulted i n a cyclic variation of the difference between the cell and nuclei cou nting techniques. This data indicates that care should be taken in int erpreting cell culture profiles based solely on crystal violet nuclei staining counts.