Endoscopic confocal fluorescence microscopy of normal and tumor bearing rat bladder

Purpose: We evaluated the possibility of performing endoscopic fiber-optic confocal microscopy in a rat bladder model and we distinguished different cell types. Material and Methods: Rhodamine 123 (Molecular Probes, Eugene, Oregon) (100 mu M) was instilled for 30 minutes in 5 tumor bearing rat bladders (AY27). Five normal rats served as controls. A Cell-vizio (TM) confocal microscopy fiber was placed transurethrally in contact with normal or transformed bladder wall. Frozen sections were obtained from the same spots and subjected to conventional fluorescence microscopy and anatomical-pathological analysis. Results: The different cells types present in rat epithelium (umbrella, intermediate and basal cells) could easily be identified with the Cell-Vizio (TM) device due to their differences in morphology and fluorescence intensity. Individual AY-27 cells could not be demarcated due to the strong fluorescence signal but the entire tumor appeared as a brightly homogenous fluorescent blot surrounded by small inflammatory cells. Conclusions: We report the feasibility of endoscopic, in vivo, fiber-optic confocal microscopy in the rat bladder. We distinguished tumors from normal epithelium and visualized the different epithelial cell types in nontransformed rat bladder epithelium.