The Photodynamic Therapy using 5-Aminolevulinic Acid(ALA): The Study of the Anti-Tumor Effect on in vitro and in vivo Experiments / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: ALA is a precursor of heme and converted to protoporphyrin IX used as effective photosensitizer. The aim of this study was to find the ideal concentration and incubation time of ALA for PDT on in vitro and in vivo experiments and to assess the anti-tumor effect of PDT using ALA on CT-26 colon cancer cell line. MATERIALS AND METHOD: CT-26 cell was cultured with serum free media including ALA in the dark room to show the intracellular accumulation of PpIX. The fluorescence of PpIX in the cell was detected under confocal laser scanning microscope. Also CT-26 cell was incubated with various concentration of ALA (1.0-0.001 mg/ml) and was irradiated with LED at 0 hr, 3 hr, 6 hr, 9 hr, 12 hr and 24 hr after application of ALA. The cell viability was assessed by MTT assay. in vivo PDT was done with optimal treatment condition and the anti-tumor effect of PDT using ALA was measured by tumor volume change. RESULTS: The fluorescence of PpIX was saturated at 6 hour after the ALA application to CT-26 cell and the optimal incubation time with ALA for PDT was 6 hours. For in vivo Study, 632 nm laser irradiation was done around the tumor 6 hours after ALA injection. The PDT using ALA on transplanted CT-26 tumors shows 40% cure rate and 40% partial remission and significant decrease of tumor volume. CONCLUSION: The peak accumulation of PpIX in the cell and in the tumor was reached 6 hours after the application of ALA. The PDT using ALA for CT-26 cells was very effective and this findings suggest that ALA is one of candidate for photosensitizer in head and neck solid tumors.