Efeitos vasculares do fotossensibilizador porfirínico meso-tetrametilpiridil na terapia fotodinâmica em modelo de membrana corioalantoide
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2020-08-06
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Universidade Federal de Goiás
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Photodynamic therapy is based on the administration of a photosensitizing substance under light activation through the emission of an appropriate wavelength in the presence of molecular oxygen. Photochemical and photophysical reactions trigger the destruction of irradiated tissue, either by cell injury or vascular injury. Therefore, the main therapeutic applications of photodynamic therapy are cancer therapy and the treatment of disorders related to neovascularization. Cationic porphyrins have chemical and physical properties that favor their use in vascular photodynamic therapy, which targets the destruction of tissue vascularization. For the development of protocols that can be used in clinical practice, the experimental model of the chicken embryo chorioallantoid membrane is used. This model allows the direct visualization and evaluation of a wide vascular network. Therefore, this study aimed to evaluate the vascular effect of photodynamic therapy, using meso-tetramethylpyridyl porphyrin applied topically to the chorioallantoic membrane, at a dose of 100µM. Images were acquired before treatment and every 30 minutes after application, until completing five hours of evaluation. This analysis was based on the general vascular response, quantifying the vascular area in pixels and obtaining the vascular reduction in percentage. In addition, the vascular effect was assessed through macroscopic and microscopic visual assessment. The main visual changes identified were vasoconstriction, thrombus formation, atrophy of the mesoderm, perivascular fibrosis, hyperemia of ectodermal capillaries and necrosis of the chorioallantoid membrane. As for vascular reduction, treatment with light irradiation (14%) or solvent alone (5%) did not show significant results, as well as treatment with photosensitizer (23%). However, the vascular reduction after photodynamic therapy was 35%. Thus, although all treatments have promoted macroscopic and microscopic changes in the membrane, the vascular reduction in the group treated with photodynamic therapy using meso-tetramethylpyridyl porphyrin was superior to the treatments with light and solvent. Thus, this treatment, under these conditions, has a potential use in the treatment of disorders that target vascularization.
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SANTANA, I. C. R. Efeitos vasculares do fotossensibilizador porfirínico meso-tetrametilpiridil na terapia fotodinâmica em modelo de membrana corioalantoide. 2020. 65 f. Dissertação (Mestrado em Ciência Animal) - Universidade Federal de Goiás, Goiânia, 2020.