Purpose: In the orthotopic animal bladder tumor model noninvasive evaluation of the tumor establishment and the therapeutic effect has been difficult. To our knowledge we present the first diagnosis of orthotopic rat superficial bladder tumor model by ultrathin cystoscopy. Materials and Methods: The established AY-27 rat bladder carcinoma cell line was transplanted orthotopically into 22 female Fischer F344 rats. A cell suspension containing 4 × 106 AY-27 cells was instilled into the bladder, which had been conditioned with mild acid washing. To evaluate tumor growth serial cystoscopy was performed via the urethra with an ultrathin endoscope (diameter 0.75 mm.) 5 to 14 days after tumor cell inoculation. At intervals after cystoscopic tumor detection the rats were sacrificed for autopsy and histological examination. Results: In all 22 rats the orthotopic bladder tumor was established 7 to 10 days after tumor cell implantation and in most it was superficial. Cystoscopy permitted inspection of the urethra and whole bladder surface. We detected all tumors as broad based papillary mass (minimal lesion 1 mm. or less) and inspected its detailed appearance and accurate location. Conclusions: The orthotopic rat superficial bladder tumor model and the diagnostic procedure by ultrathin cystoscopy would be ideal system for preclinical evaluation of new potential intravesical therapies.
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