Photodynamic Therapy with three photosensitisers in the HEP-2 human cell line.

ALVAREZ, GABRIELA; RIVAROLA, VIVIANA; FUKUDA, HAYDÉE; BATLLE, ALCIRA

Rotterdam

Congreso; PORPHYRINS and PORPHYRIAS 2007; 2007

Introduction: AII living cells form Haem from Aminolevulinic acid (ALA). After exogenous administration, ALA is converted into the photosensitiser (PS) Protoporphyrin IX (PPIX). PPIX is accumulated in malignant cells. After exposure to light, activated PPIX generates reactive oxygen species which conduce to cell death, the so-called Photodynamic Therapy (POT).   In this work we have evaluated the photokilling activity of three PSs on the Hep-2 cells.   Materials and Methods: The Hep-2 human larynx carcinoma cell line and the following PSs were used: molecular dyad porphyrinC-(60) (P-C(60)); the monocationic porphyrin derivative 5-(4-trimethyl ammoniumphenyl)-1 0,15,20tris (2,4,6-trimethDxyphenyl) porphyrin (CP) and PPIX synthesized in situ from ALA. The mechanism of cell death was analyzed ,by Hoechst -33258 and toluidine blue staining, TUNEL assay and ONA fragmentation.   !¡ Results: No darK,cytotoxicity was observed with 1 mlJM PC (60 ), 5 IJM CP or 1 mM ALA along the 24 h incubation. Cell survival aft~r~irradiation with visible light was dependent on incubation time. Cells treated 24 h with PC(60) and irradiated with .f54 J/cm2 showed 58 % of apoptosis. Instead, under these conditions, CP induced a 58 % of necrosis. PPIX accumulated after incubation with 1 mM ALA for 45 h induced 40 % of apoptosis. Upon irradiation in anaerobiosis of cells incubated with P-C(60), necrosis predominated over apoptosis. Microscopy under violet-blue light, revealed that f1uorescence of CP was localized in mitochondria, while ALA-induced PPIX was localized in Iysosomes.   Conclusion: Photodamage in POT is dependent on the PS, light dose and the atmosphere conditions.