Reconstitution of immune cell in liver and lymph node of adult- and newborn-engrafted humanized mice

Crystal Dykstra, Amanda J. Lee, Evan J. Lusty, Mira M. Shenouda, Mahsa Shafai, Fatemeh Vahedi, Marianne V. Chew, Stephen Collins, Ali A. Ashkar

Humanized mouse models are an increasingly popular preclinical model to study the human immune response in a biological system. There are a variety of protocols to generate these mice, each differing in the strain of the recipient, source of hematopoietic stem cells, and mode of transplantation. Though there is well-documented reconstitution information regarding the spleen, blood, and bone marrow, there is little information regarding reconstitution of the lymph node and liver. In this report, we sought to compare reconstitution levels in a variety of immunological tissues, including the lymph node and liver, between mice engrafted intravenously as adults and intrahepatically in newborns. CD34+ cells were enriched from cord blood and transplanted intravenously into irradiated adult NOD-Rag1(-/-)IL2rγ(-/-) (NRG) mice or intra-hepatically into irradiated newborn NRG mice. At 9-28 weeks post-engraftment, immunological tissues were processed and analyzed for human lymphoid and myeloid subsets. Adult and newborn engrafted humanized mice were comparable in long-term reconstitution of human CD45 cells and subsequent lymphoid and myeloid subsets in the spleen, bone marrow, thymus, lymph node, and liver. Mice engrafted as newborns had a higher level of T-cells and a lower level of B-cells compared to mice engrafted as adults. We observed significant levels of human immune cell engraftment in both the lymph node and the liver, with a predominant adaptive immune population in both compartments. Human immune cells repopulate liver and mesenteric lymph nodes of NRG mice and can be used to study the human immune system in the gastrointestinal tract.