Photodynamic therapy (PDT) is a promising new treatment for malignant and non-malignant diseases. The procedure requires exposure of cell to a photosensitizing drug followed by irradiation with visible light of the appropriate wavelength in presence of molecular oxygen. The primary role of PDT is to kill unwanted photodynamic cell by two mechanisms apoptosis and necrosis. This work describes the photophysical properties, accumulation, localization and the modes of cell death of tetra methoxy Zn II phthalocyanine on Hep-2. The first analysis showed that cell survival (MTT assay) was no affected in light alone. Both incubation time 6h and 18h with different concentrations 0.1µM and 0.5µM did no induce dark toxicity. On the contrary, when Hep-2 cells were incubated with ZnPcOCH3 and post-irradiated with different light dose it was found an efficiency cell photokilling in drug concentration, irradiation time and post-PDT time dependent manner. On the other hand, we observed that the most of sere cells present morphology apoptotic 24 h post-PDT using 0.5µM of ZnPcOCH3 and 5 min irradiation. The immunocytochemistry biotin-avidin– peroxidase (ABC) method confirmed expression of caspase 3. On the contrary, 15 min irradiation and 24h post-PDT produced necrosis cell (Hoechst-33258, Toluidine blue and DNA fragmentation). Hep-2 cultures incubated with ZnPcOCH3 exhibited a perinuclear fluorescence suggesting that ZnPcOCH3 localizes in lysosome. Due to that in vitro model ZnPcOCH3 showed a high photosensitizing efficiency, we further investigate its behaviour in vivo model.
Grants: CONICET, FONCYT and SECYT UNRC.
