Bioluminescence monitoring of photodynamic therapy response of rat gliosarcoma in vitro and in vivo

Abstract

Photodynamic Therapy (PDT) is a promising modality for tumor treatment that combines a photosensitizing agent and visible light resulting in the production of cytotoxic reactive oxygen species leading to cell death. Bioluminescence detection/imaging is a noninvasive technique that uses luciferase gene transfection together with administration of luciferin to generate detectable visible light. It can provide real-time assessment of tumor growth and therapeutic response. The aim of this study is to investigate the potential fo bioluminescence following animolevulinic acid (ALA)-mediated PDT. The in vitro results show a decrease of luminescence, with an excellent correlation to the number of viable cells. In vivo, the tumor growth was monitored using a cooled CCD camera, and ALA-PDT was performed 7-10 days post tumor implantation. The results show a decrease of the bioluminescence signal from the tumor that corresponds to a decrease of viable cells within the tumor, followed by re-growth at the sub-curative PDT doses used.