RESPUESTA DE CÉLULAS HIPOFISARIAS AL ESTRÉS OXIDATIVO PRODUCIDO POR RIBOFLAVINA EN TERAPIA FOTODINÁMICA

A. V. JUAREZ; N. BOETTO; E. HAGGI ; P. PONS

ACTA MICROSCOPICA

Acta microscopica

Lugar: Caracas; Año: 2013 vol. 22 p. 228 - 238

0798-4545

Hypothesis: Riboflavin could be used as a photosensitizer (PS) in photodynamic therapy (PDT) because of its high quantum yield of O2(1Δg). The aim of our investigation was 1) to evaluate ultrastructural changes of epithelial cells in response to riboflavin (RF)-PDT, 2) to identify if reactive oxygen species (ROS) were produced and 3) to determine if cell death was induced and which type. Materials and methods: RF was acetylated to obtain liposoluble riboflavin (RFL) with improved penetration through the plasmatic membrane. 3-hydroxy pyridine and 9-10 dimethylanthracene, compounds that decompose in the presence of O2(1Δg) were used to verify the generation of ROS by light activation (λ = 460 nm) of both RF and RFL. To evaluate the potential damage in rat pituitary cells in culture caused by PDT, cell viability was measured with trypan blue exclusion assay and ultrastructural alterations were analyzed by transmission electron microscopy and photonic high-resolution microscopy. Antioxidants catalase (75 U/ml), superoxide dismutase (100 U / ml) and L-histidine (10 mM) were used to estimate ROS involved in cytotoxicity. Results: both RF and RFL, generate ROS when activated by light (460 nm, 10 mW/cm2), inducing cell death by two morphologically distinct mechanisms, necrosis and apoptosis. Conclusion: The cytotoxicity of irradiated RF or RFL allowed us to propose their effectiveness as PS in PDT application.