Subcellular localization of porphyrins using confocal laser scanning microscopy.

The in vitro subcellular distribution patterns of 10 porphyrins, varying in hydrophobicity and charge, were studied using confocal laser scanning microscopy on two cell lines (V79 and C6 glioma cells) for incubation times up to 24 h. All of the porphyrins were taken up rapidly by both cell lines and distinct classes of subcellular distribution patterns were observed: general cytoplasmic staining; localization in lysosomes (usually associated with general cytoplasmic staining); localization in mitochondria (and general cytoplasmic staining); localization in mitochondria with subsequent uptake into lysosomes. Structure-localization relationships which have emerged are that porphyrins with dominantly cationic side chains localize in mitochondria, whereas those with a more anionic character tend to localize in lysosomes.