Analysis and sorting of living cells according to deoxyribonucleic acid content.

The methods for measuring the deoxyribonucleic acid content of individual mammalian cells and sorting them on the basis of this parameter have until now required fixation or other treatment which renders the cells nonviable. Using a class of bis-benzimidazole dyes, Hoechst 33258 and 33342 and a multiparameter computer-controlled cell sorter, we have been able to stain and separate living cells in the G1, S, and G2+M phases of the cell cycle and to continue their growth in tissue culture with high retention of viability (greater than 90%) and no increase in heteroploidy. The quenching of the fluorescence of the bound dye by 5-bromodeoxyuridine incorporated into cellular deoxyribonucleic acid is being used with the flow system to detect and isolate mutants in deoxyribonucleic acid metabolism spectroscopically.