GROWTH, FLUORESCENCE AND METACHROMASY OF CELLS CULTURED IN THE PRESENCE OF ACRIDINE ORANGE

Abstract

Four types of animal cells were cultured in perfusion chambers in medium containing acridine orange and serially observed by phase and fluorescence microscopy, so that cellular injury from toxic and photodynamic effects of acridine orange could be correlated with the variable fluorescence images of the cells. Spontaneous movements of pigment granules in healthy chorioidal and ciliary melanocytes provided a valuable criterion of cellular health. Dye concentrations of 10 –6 gm/ml permitted healthy outgrowth of brilliantly fluorescent cells for at least 20 days, but higher concentrations were lethal. Uninjured living cells had orthochromatic (green) fluorescence. Reversibly injured cells acquired metachromatic (red-fluorescent) cytoplasmic granules which might be identical with mitochondria or with the neutral red granules of Jackson. With irreversible photodynamic injury, ribonucleic acid of nucleoli and cytoplasm stained metachromatically; deoxyribonucleic acid of nuclei alnsost always remained orthochromatic. As degeneration ensued, cells lost first their metachromasy, finally all their fluorescence. The variable fluorescence images of living, injured, killed, degenerated and fixed cells stained with acridine orange may be explained according to the theory of variable stacking of bound dye molecules.