Avaliação da fluorescência da protoporfirina IX em modelo tumoral de pele em camundongo na aplicação de terapia fotodinâmica utilizando sistema portátil com baixa irradiação

Abstract

Photodynamic therapy (PDT) is a topical treatment option used for non-melanoma skin cancer and pre-malignant skin lesions. PDT develops with the interaction of a photosensitizer (PS), light with adequate wavelength in the presence of oxygen molecules in the tissue, causing cell death. In Brazil, there are treatments with well-defined and approved protocols using protoporphyrin IX (PpIX) as FS, through the topical application of a cream containing its precursor (methyl aminolevulinate) and commercial irradiation equipment LINCE®. A new treatment proposal, with a portable irradiation system developed by the Technological Support Laboratory (LAT) of the Optics Group of the São Carlos Institute of Physics (IFSC) of the University of São Paulo (USP) was tested in order to optimize the length of stay of patients in the hospital. This project aimed at the comparative study of PpIX activation and degradation by the portable system with the commercial irradiation system. This study was carried out using a tumor model in mice, evaluating different protocols (variation in irradiation and incubation time) through fluorescence spectroscopy and wide-field fluorescence imaging to compare the production and degradation of PpIX in the tumor and in the surrounding skin. With the results obtained, it was possible to verify that the degradation of PpIX was similar in the use of the portable irradiation system (prototype) and the commercial system (LINCE), both by the analysis by fluorescence spectroscopy and by wide-field fluorescence images.