Evaluation of cell death mechanisms induced by photodynamic therapy using different photosensitizers

Abstract

Cancer is a disease caused by an uncontrolled division of abnormal cells in a particular part of the body. Many types of Cancer exist and Skin Cancer is a major Cancer faced by Brazilian. Among the available treatments, Photodynamic Therapy (PDT) is a light induced chemoreaction process that utilizes a Photosensitizer (PS), activated when exposed to light at a specific wavelength, to induce cancer cell death. The aim of this study is to investigate the induced cell death mechanisms when performing PDT with different photosensitizers. Even though, PDT has been already used for decades, the cellular death mechanisms andtheir relation with the final tumor destruction are not completely understood, when comparing the different photosensitizers. Skin Cancer cells and xenograft mice will be used to evaluate the cell death mechanisms at cellular level (in vitro) and at tumor (in vivo). The photosensitizers that will be investigated are: porphyrin, chlorine, and ALA-PpIX. The nanoencapsulated delivery will also be a subject in this project. The in vitro study will investigate cellular morphology, proliferation, viability, cytotoxicity, protein activities and cell death mechanisms, especially considering autophagy. Characterization of the intracellular distribution, and the induced organelles and membrane damage will provide insights for the cell death behavior. Finally, the in vivo study will provide the understanding on how the cell death mechanisms vary depending on the photosensitizer type and are correlated with the final PDT response at the tumor extracellular matrix and vascularization. Experimental analysis will include: flow cytometry, homogenate analysis, protein expression, confocal microscopy, Raman microspectroscopy, wide field fluorescence imaging, fluorescence spectroscopy and, optical coherence tomography. (AU)