Introducing a novel experimental model of bladder transplantation in mice.

Bladder dysfunction is a common clinical problem attributed to various conditions such as posterior urethral valves, neurogenic bladder, ureteral ectopy, or bladder exstrophy. Currently, the main therapeutic option for these dysfunctions is neobladder reconstruction with gastrointestinal tract segments. However, the latter was associated with significant long-term complications. To provide a new candidate of possible surgical solution for bladder dysfunction, we propose a novel orthotropic mouse bladder transplantation model. The donor bladder with abdominal aorta and inferior vena cava was isolated and orthotopically sutured to the recipient, whose bladder above the ureteral opening level was removed. The recipient mice showed more than 80% 6-month survival rate and comparable body weight to control mice. At both 1 month and 6 months posttransplant, the urine voiding behavior of recipient mice and control mice was monitored by cystometry. We found that the recipient mice displayed similar bladder pressure and urine secretion ability compared to control mice especially at 6 months posttransplant. Similarity of bladder structure between recipient and control mice was confirmed by histology. As a proof of principle, we tested our model in an allogeneic setting. Early acute rejection was noted after day 5 that was histologically more profound by day 10 posttransplant. These results indicate that the mouse bladder transplant is able to provide normal bladder function.