RESUMO
<p><b>OBJECTIVE</b>A mouse model of orthotopic bladder cancer simulating its human counterpart is of great importance in preclinical evaluation of new treatment modalities such as immunotxin therapy. The aim of the present study is to establish a novel nude mouse model with xenografted human bladder cancer.</p><p><b>METHODS</b>Single cell suspension of an established human bladder transitional cell carcinoma (TCC) cell line BIU-87 was instilled into nude mouse bladders which were pretreated with mild acid washing. The tumor growth in mouse bladder was assessed weekly by magnetic resonance imaging (MRI). At intervals following implantation and MRI tumor detection, the animals were sacrificed for necropsy, histological examination and immunocytochemical studies.</p><p><b>RESULTS</b>The overall tumor establishment was 92.9% (52/56 mice) at 7 - 36 days, while in the subgroup of animals sacrificed at 12 - 13 days, 40 out of 42 animals (95.2%) developed TCC, the majority of which was superficial. The tumor stages were assessed by gross and histopathology. Histological examination confirmed the presence of grade II - III TCC. Immunocytochemistry confirmed that the tumor model maintained the biological and immunological features of BIU-87 cells. The changes seen on MRI images well correlated with the extent of tumor invasion identified by histology. Carcinoma in situ could be detected histologically at 7 - 9 days post-inoculation and progressed into papillary or invasive tumors thereafter.</p><p><b>CONCLUSION</b>The orthotopic BIU-87 TCC model in nude mice is highly reproducible and is ideal for preclinical studies on experimental intravesical therapies.</p>