Portal versus systemic transplantation of dispersed neonatal pancreas

It is not known whether the advantage of the portal vein as a transplant site for islet transplantation is caused by the immediate availability of a blood supply or by the localization of the islets in the portal circulation. We transplanted minimal quantities of islet tissue from neonatal rat donors to isogeneic adult rats with streptozotocin-induced diabetes. Transplants were performed to three sites, i.p., portal vein, and systemic vein (i.v.). When four neonatal donors were used for each recipient there were no i.p. cures but 90% i.v. and 100% portal vein cures, which suggests that access to a blood supply is important. As the amount of tissue transplanted was decreased, there were significantly more cures with the portal vein route, which suggests that localization of the islets in the portal circulation is also important to graft survival.