GRAFTING OF FETAL PANCREASES INTO NEONATAL RAT-BRAIN

Undigested fetal pancreatic tissue has been previously shown to have immunogenic properties, even after transplantation into the adult rat brain, a relatively immunoprivileged site. In the present study, iso-, alio-, and xenografts of fetal pancreas were placed into neonatal rat brain parenchyma and ventricles in order to determine the extent and quality of its survival in this environment. Adult recipients of the same tissue types were used as controls. Selective survival of insulin-staining beta cells was observed in neonates (n=33) over the 6-week period of the experiment. Ducts and acini were gradually destroyed in alio- and xenografts, disappearing completely by the 42nd day, while there were no such changes in the isografts. The absence of an acute inflammatory reaction was noted, but there were varying degrees of lymphocytic infiltration, though small (20 ± 4 lymphocytes per average graft area of 0.16 mm2) in all but one graft. This infiltrate was greatest in allografts, with a significant increase observed after 14 days, corresponding to the time when the ducts started to disappear. Other structures present included fibroblasts and blood vessels. The latter increased significantly with time after transplantation. Unlike isografts placed in the parenchyma of adult rats, alio- and xenografts were rejected from the earliest time observed, 7 days postoperatively. In summary, these data show that beta cells in rat fetal pancreas will survive when grafted across major allogeneic and xenogeneic barriers for up to 6 weeks, without utilization of any form of immunosuppression, provided the recipients are neonates. © 1990 by Williams & Wilkins.