Evaluation of the Photodynamic Therapy effect using a tumor model in Chorioallantoic Membrane with Melanoma cells

Abstract

Photodynamic Therapy (PDT) is a type of cancer treatment that is based on the interaction of light (with specific wavelength), a photosensitizing agent and molecular oxygen. The photosensitizer (PS) is activated by light and reacts with oxygen resulting in the production of singlet oxygen that is highly reactive and responsible for the cell death. The Chick Chorioallantoic Membrane (CAM) model is a transparent membrane that allows visualization and evaluation of blood vessels and structural changes, where a tumor model was developed. Two induction tumor models were investigated: tumor biopsy or cell culture. It was used a murine melanoma cell B16F10 in culture and a biopsy from a xenograft tumor in hairless mouse. Two PS were tested: Photodithazine ® and Photogem ® , a chlorine and porphyrin compounds, respectively. Using intravenous administration, the light-drug interval was of 30 minutes, 1 and 3 hours. Illumination was performed at 630 nm and 660 nm, and the vascular and tumor response was monitored and analyzed. The PS distribution was checked with confocal microscopy. This model can be useful to study several parameters of PDT and the effect of this therapy in the cancer treatment since it allows direct visualization of its effects.

Montagem e caracterização de um microscópio óptico não linear para imagens de tecidos biológicos

“…Estudos de modelo tumoral em membrana corioalantóica com células de melanoma murino estão em desenvolvimento no laboratório de Biofotônica. [57][58] Assim, o microscópio foi adaptado para adquirir imagens do tumor dentro do ovo. Essa adaptação permitiu que o ovo ficasse sob a objetiva e a região onde o tumor estava presente próxima ao ponto focal da objetiva.…”

“…Como o vaso sanguíneo é uma forma de alimentação e crescimento do tumor, era esperado que as células buscassem a região em torno do vaso. [57][58] As imagens adquiridas mostraram claramente esse comportamento das células tumorais. Na literatura é definida uma "janela óptica" entre 650 -950 nm 12…”