Photodynamic diagnosis of colitis-associated dysplasia in a mouse model after oral administration of 5-aminolevulinic acid.

Detection of dysplastic lesions in mouse colonic tissue was investigated by accumulation of photosensitizer protoporphyrin IX (PpIX) induced by oral administration of 5-aminolevulinic acid (5-ALA), a precursor of PplX.Inflammatory oncogenesis was induced in C57BL/6J-Apc(Min) (Apc(Min/+)) mouse by oral administration of dextran sodium sulfate (DSS). After oral administration of 5-ALA, the colonic tissue was observed by autofluorescent stereoscopy and histopathological examination. The localization of fluorescence signals in the colonic tissue was determined with a mobile ultraviolet Xe lamp light.Several small polypoid lesions were found in the mucosal layer of DSS-treated Apc(Min/+) mice. Strong reddish ring-shaped fluorescence signals of PpIX, at 635 nm measured by a spectrum analyzer, were observed on the mucosal surface of all protruding lesions that were confirmed to be histopathologically dysplastic.Photodynamic diagnosis with 5-ALA was useful in detecting dysplastic lesions in the colonic mucosa in a mouse model.