Advances in Photodynamic Therapy Assisted by Electroporation

Low invasive therapies of cancer are directed toward the methods that target selectively on carcinoma cells. Photodynamic therapy (PDT) is a therapeutic modality in which combination of a photosensitizer, light, and oxygen renders reactive oxygen species (ROS) which cause damage to a tumor tissue. Each of these factors is not toxic in itself and the effect of therapy results from high uptake of a photosensitizer by carcinoma cells and directed tumor irradiation by light. Realization of the therapy depends on efficient transport of the photosensitizer across the membrane and intracellular accumulation of the drug. Depending on the treatment conditions and the uptake mechanism, sensitizers can potentially reach different intracellular concentrations and different cellular effects can be triggered. Transport efficacy can be significantly augmented by applying electric pulses to plasma membrane, which opens transient non-selective hydrophilic nanopores as additional pathways across lipid membranes. Electroporation (EP) has been utilized to facilitate drug uptake in electrochemotherapy (ECT) and has been tested in combination with PDT. In the review, we described effects of PDT and electrophotodynamic therapy (EPDT) on carcinoma and healthy cells, studied in vitro and vivo. The comparison of different drugs has been applied to tests considering the enhancement of their cytotoxicity, selectivity, and additional effects caused by electroporation. Keywords: Photodynamic therapy, electrochemotherapy, electroporation, cancer, PDT, ROS, Photosensitizer, EPDT, EP, Cytotoxicity, ECT