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

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 of bioluminescence using in vitro and in vivo models to provide quantitative spatial and temporal information of brain tumor response (9L murine gliosarcoma) 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.