Newly developed mini-endoscope for diagnosis and follow-up of orthotopic bladder transitional-cell carcinoma in vivo

BACKGROUND AND PURPOSE: Orthotopic models of bladder transitional-cell carcinoma (TCC) are indispensable to the development of new intravesical agents for the treatment of non-muscle-invasive disease. Visual inspection of induced tumors and normal urothelium is of crucial interest when evaluating growth patterns and the potential effects of instillation therapies. The aim of our study was to test the practicability of a newly developed mini-endoscope in terms of the benefit and reproducibility of repeated diagnostic cystoscopy in a rat model, thus mimicking standard procedures in patients. MATERIALS AND METHODS: The study group consisted of 24 Foxn(rnu) athymic nude rats. In 18 animals, a suspension of the human TCC cell line UMUC-3 was instilled into the urinary bladder after trypsinization. Six animals underwent bladder trypsinization only and served as a control group. Follow-up cystoscopy was performed weekly. A newly developed semirigid mini-endoscope (Karl Storz, Tuttlingen, Germany), 0.89 mm in diameter, was used. RESULTS: In total, 213 cystoscopies were performed. Each animal underwent at least seven procedures at weekly intervals over a period of 2 months. All tumors were detected by the mini-endoscope within 14 days of tumor-cell implantation. Cystoscopy provided visibility of the entire lower urinary tract (LUT), with the smallest detectable lesion being 0.5 mm in diameter. The regularly performed cystoscopy was tolerated without any significant procedure-related morphologic alterations in the LUT. CONCLUSIONS: The new mini-endoscope constitutes a practicable and reliable tool for diagnosis and regular follow-up cystoscopy in rats. This instrument can contribute to the preclinical development of experimental intravesical antitumor agents when used for regular evaluations of morphologic drug effects in vivo.