In vitro and in vivo effects of HAL on porphyrin production in rat bladder cancer cells (AY27)

Aminolevulinic acid and hexyl-aminolevulinate serve as biological precursors to produce photosensitive porphyrins in cells via the heme biosynthetic pathway. This pathway is integral to porphyrin-based photodynamic diagnosis and therapy. By adding exogenous hexyl-aminolevulinate to rat bladder cancer cells (AY27, in vitro) and an animal bladder cancer model (in vivo), fluorescent endogenous porphyrin production was stimulated. Lipophilic protoporphyrin IX was identified as the dominant species by reverse high-pressure liquid chromatography. Subcellular porphyrin localization in the AY27 cells was evaluated by confocal laser scanning microscopy and showed almost quantitative bleaching after 20 s. From this study, we ascertained that the protocol described herein is suitable for hexyl-aminolevulinate-mediated photodynamic therapy and diagnosis when protoporphyrin IX is the active agent.