Human Immune System Development and Rejection of Human Islet Allografts in Spontaneously Diabetic NOD-Rag1null IL2rγnull Ins2Akita Mice

Abstract

OBJECTIVE To create an immunodeficient mouse model that spontaneously develops hyperglycemia to serve as a diabetic host for human islets and stem cell–derived β-cells in the absence or presence of a functional human immune system. RESEARCH DESIGN AND METHODS We backcrossed the Ins2Akita mutation onto the NOD-Rag1null IL2rγnull strain and determined 1) the spontaneous development of hyperglycemia, 2) the ability of human islets, mouse islets, and dissociated mouse islet cells to restore euglycemia, 3) the generation of a human immune system following engraftment of human hematopoietic stem cells, and 4) the ability of the humanized mice to reject human islet allografts. RESULTS We confirmed the defects in innate and adaptive immunity and the spontaneous development of hyperglycemia conferred by the IL2rγnull, Rag1null, and Ins2Akita genes in NOD-Rag1null IL2rγnull Ins2Akita (NRG-Akita) mice. Mouse and human islets restored NRG-Akita mice to normoglycemia. Insulin-positive cells in dissociated mouse islets, required to restore euglycemia in chemically diabetic NOD-scid IL2rγnull and spontaneously diabetic NRG-Akita mice, were quantified following transplantation via the intrapancreatic and subrenal routes. Engraftment of human hematopoietic stem cells in newborn NRG-Akita and NRG mice resulted in equivalent human immune system development in a normoglycemic or chronically hyperglycemic environment, with >50% of engrafted NRG-Akita mice capable of rejecting human islet allografts. CONCLUSIONS NRG-Akita mice provide a model system for validation of the function of human islets and human adult stem cell, embryonic stem cell, or induced pluripotent stem cell–derived β-cells in the absence or presence of an alloreactive human immune system.