Fetal Islet Transplantation and Pregnancy

Several animal models are now available for the study of pregnancy complicated by diabetes mellitus and thus studies of islet transplantation in these pregnant animals can also be performed. Animals may be made hyperglycemic by the use of alloxan or streptozotocin. Infusion protocols of glucose and/or insulin have been described in several species including rats and monkeys. Recently described genetic models include the BB Wistar rat, the NOD mouse, the C57/KsJdb+/+m mouse, and the Chinese hamster with spontaneous diabetes (CHAD). The NOD mouse is particularly attractive for studies of transplantation since it has several features in common to the human autoimmune counterpart. Studies of subcutaneous fetal islet transplantation in this model as well as in humans during gestation suggest improved graft survival and insulin secretory capacity. The nature of the factors during pregnancy that lead to enhanced tissue vascularization, improved tissue growth and secretory capacity, and decreased immunological response in pregnant recipients are noteworthy and warrant further study.