Pancreas islet transplantation in the genitourinary tract associated with renal transplantation: an experimental study.

Conceptually, pancreas islet transplantation (PIT) associated with renal transplantation (RT) should resolve not only chronic renal failure but also diabetes. Although the most frequently used site for PIT is the portal vein, genitourinary locations could be technically feasible during RT. Seventeen pigs (age 3 to 4 months; mean weight 34.5 kg) underwent the following experimental steps: On day 1 a left nephrectomy was performed and the kidney was perfused with cold Wisconsin solution. This was followed by a caudal pancreatectomy and islet isolation by means of digestion with intraductal collagenase. Islets were stained with Dithizone and cultured overnight al 37 degrees C and 5% CO(2). On day 2 a right nephrectomy and orthotopic RT of the preserved left kidney were performed. The islets were transplanted into four different sites: subcapsular in the kidney graft, in the bladder submucosa, in the testis by puncture, and in the testis by infusion through the vas deferens. On day 7 the animals were sacrificed. Islet viability was determined by histological examination with insulin immunostaining and determination of insulin in the blood of the veins draining the implantation sites. The mean weight of the pancreatic specimens was 27.8 g (13 to 46). The mean number of islets was 536,000 (16,600 to 1,5000,000). Islets were shown in the bladder submucosa and the testes after vas deferens infusion. The number of viable islets in the other implantation sites was very scarce. The insulin levels of the venous effluents were: 15.1 microU/mL for bladder submucosa, 10.2 microU/mL for intradeferential injection in the testis, 7.3 microU/mL for intratesticular injection by puncture, and 2.6 microU/mL for subcapsular implantation in the graft. In conclusion, the bladder submucosa and testis via the vas deferens might represent alternative sites for PIT. The latter route may benefit from the immunoprivileged and special trophic conditions of the testis. For the first time, the feasibility of the bladder submucosa as an implantation site for pancreas islets was demonstrated.