Fetal rat pancreas transplantation in BB rats: immunohistochemical and functional evaluation.

Spontaneously diabetic BB/Wor rats received either a syngeneic fetal pancreas transplant or adult islets. In the former, 4-8 fetal pancreases were transplanted, and in the latter, 3-5000 islets. Transplantation was performed by transferring a blood clot containing the pancreases or islets to the renal subcapsular space. Insulin therapy was undertaken postoperatively, except in one experiment with adult islets. Of the fetal pancreas transplanted BB rats, 52% became normoglycaemic, and 21% remained so throughout an observation period of 10 months. Nephrectomy caused a prompt return of diabetes. The histological appearance of the grafts transplanted to the diabetic animals closely resembled that of grafts transplanted to normal rats in a parallel series. For comparison a group of BB rats received a syngeneic transplant of isolated adult islets from WF rats or BBW rats. Following adult islet transplantation, 5 out of 6 animals became hyperglycaemic after a median of 20.5 days when no insulin was given post-transplantation. Four out of 5 animals became hyperglycaemic after a median of 23 days when supportive insulin therapy was administered after the transplantation. The results indicate that recurrent diabetes is not inevitable following syngeneic fetal pancreas transplantation to spontaneously diabetic BB rats. Recurrent diabetes was only occasionally associated with mononuclear cell infiltration. Transplanted tissue was well-preserved and vascularized; mega-islets were a constant finding.