A NUDE RAT MODEL FOR IN-VIVO STUDIES OF HUMAN TRANSITIONAL-CELL CARCINOGENESIS

A xenograft system was developed for studying experimental carcinogene sis of human transitional cells in vivo. Segments of human ureters wer e tied to an injection port, ligated at the opposite end, implanted in to gamma-irradiated nude rats and weekly irrigated through the injecti on port with fresh PBS solution. Such implants maintained the normal h istologic appearance of human urothelium for at least 20 weeks in vivo in the nude rats. In situ hybridization with a human repetitive seque nce DNA probe showed that the urothelium and the submucosal connective tissue and smooth muscle were of human origin. The urothelial lining was positive with an immunohistochemical reaction for acidic cytokerat ins. This model allows for the long-term direct exposure of human urot helium to bladder carcinogens for the purpose of induction of human tr ansitional cell tumors.