Intracellular Localization and Phototoxicity Mechanisms of Chlorin e6 Derivatives and their Liposomal Formulations

Abstract

Confocal microscopy and colocalization analysis using Pearson correlation coefficients were used to show that esterified chlorin e6 derivatives and their liposomal forms are mainly localized in the endoplasmic reticulum, Golgi complexes, cell mitochondria, and levels of their localization in lysosomes are low. Cellular uptake and accumulation kinetics of chlorin e6 derivatives were strongly depended on the type of pharmacological formulation used for photosesitizers administration, while intracellular localization was independent on the formulation. Differences in the photodynamic activity and sensitization mechanisms for chlorin e6 derivatives and their liposomal forms were shown when compared to those of chlorin e6 photosensitizers in K562 cells. It is assumed that the observed differences in the mechanisms of cellular damage are toa greater extent due to specific photosensitizer localization.