Intermediate or high-risk non-muscle invasive bladder cancer that is refractory to Bacillus Calmette-Guérin has limited treatment options. Intravesical chemotherapy has limited efficacy, and radical cystectomy with urinary diversion, though effective in terms of recurrence-free survival, has a high rate of complications. As an alternative to radical cystectomy with urinary diversion in patients with recurrent non-muscle invasive bladder cancer, we propose to replace the bladder urothelium. The basis of this proposal centers upon our work in understanding how in the mouse, a lesion similar to human carcinoma in situ (CIS) develops from exposure to a carcinogenic agent and extensively proliferates to involve most, if not all, of the urothelium, necessitating complete urothelial replacement to avoid cancer recurrence and progression. In order to replace the urothelium, we must develop methods to generate bladder urothelial progenitor cells, and we propose to do this through transdifferentiation of fibroblasts. We will also develop methods to exfoliate the urothelium and transplant these cells, as well as measure the extent of the premalignant lesion. We hypothesize that replacement of the urothelium with urothelial progenitor cells from transdifferentiation will definitively prevent progression and recurrence of non-muscle invasive bladder cancer.