Ex vivo fluorescence imaging of normal and malignant urothelial cells to enhance early diagnosis
Résumé
Urinary cytology is a noninvasive and unconstraining techniquefor urothelial cancer diagnosis but lacks sensitivity for detectinglow-grade lesions. In this study, the fluorescence properties ofclassical Papanicolaou-stained urothelial cytological slides frompatients or from cell lines were monitored to investigatemetabolic changes in normal and tumoral cells. Time- andspectrally-resolved fluorescence imaging was performed at thesingle cell level to assess the spectral and temporal properties aswell as the spatial distribution of the fluorescence emitted byurothelial cells. The results reveal quite different fluorescencedistributions between tumoral urothelial cells, characterized by aperimembrane fluorescence localization, and the normal cellswhich exhibit an intracellular fluorescence. This is not caused bydifferences in the fluorescence emission of the endogenousfluorophores NAD(P)H, flavoproteins or porphyrins but byvarious localization of the EA 50 Papanicolaou stain as revealedby both the spectral and time-resolved parameters. The presentresults demonstrate that the use of single-cell endofluorescenceemission of Papanicolaou-stained urothelial cytological slidescan allow an earlyex vivodiagnosis of low-grade bladdercancers.