Humanized mice are an invaluable tool for investigating human diseases such as cancer, infectious diseases, and graft-versus-host disease (GvHD). However, it is crucial to understand the strengths and limitations of humanized mice and select the most appropriate model. In this study, we describe the development of the human lymphoid and myeloid lineages using a flow cytometric analysis in four humanized mouse models derived from NOD mice xenotransplanted with CD34⁺ fetal cord blood from a single donor. Our results showed that all murine strains sustained human immune cells within a proinflammatory environment induced by GvHD. However, the Hu-SGM3 model consistently generated higher numbers of human T cells, monocytes, dendritic cells, mast cells, and megakaryocytes, and a low number of circulating platelets showing an activated profile when compared with the other murine strains. The hu-NOG-EXL model had a similar cell development profile but a higher number of circulating platelets with an inactivated state, and the hu-NSG and hu-NCG developed low frequencies of immune cells compared with the other models. Interestingly, only the hu-SGM3 and hu-EXL models developed mast cells. In conclusion, our findings highlight the importance of selecting the appropriate humanized mouse model for specific research questions, considering the strengths and limitations of each model and the immune cell populations of interest.

Hematopoietic stem cell transplantation is one of the most intricate immune therapies used for patients with hematological diseases or immune disorders. In addition to the inherent immunosuppression from their primary condition, many of these patients usually receive cytotoxic chemotherapy, radiation therapy, broad-spectrum antibiotics, or experience extended nutritional perturbations. These factors collectively lead to inflammation and the disruption of gut microbiota. Additionally, about 40–60% of patients undergoing fully HLA-matched allogeneic transplantation are expected to develop acute graft-versus-host disease (aGVHD), even with prophylactic measures such as calcineurin inhibitors, methotrexate/mycophenolate, or post-transplant cyclophosphamide treatment. Recent research has elucidated the complex interplay between immune effectors in the gastrointestinal tract and microbial populations within a proinflammatory peri-transplant environment, revealing its significant effect on survival and post-transplant complications such as aGVHD. This review will explore the relationship between dysbiosis during allogeneic transplantation and mechanisms that can help clarify the link between gut microbiota and the risk of GVHD, along with emerging therapeutic strategies aimed at addressing dysbiosis during hematopoietic stem cell transplantation.

Dengue is a significant public health problem with no specific viral treatment. One of the main challenges in studying dengue is the lack of adequate animal models recapitulating human immune responses. Most studies on humanized mice use NOD-scid IL2R gamma null (NSG) mice, which exhibit poor hematopoiesis for some cell populations. This study compares three humanized (hu) NOD-derived mouse models for dengue virus-2 (DENV-2) infection in the context of human cytokine expression. Three mouse strains (hu-NSG, hu-EXL, and hu-SGM3) received xenotransplants of human CD34+ fetal cord blood cells from a single donor, and one mouse strain received human peripheral blood mononuclear cells (hu-SGM3-PBMCs). All models exhibited infectious viruses in blood confirmed by plaque assay, but mice expressing human cytokines showed higher viremia compared to conventional NSG mice. The hu-SGM3-PBMCs model developed lethal infections, showing a significant increase in viremia and clinical signs. A detectable human cytokine response was observed in all the DENV-2-infected humanized mouse models. In conclusion, humanized NOD-derived mouse models expressing human cytokines offer a relevant platform for the study of dengue pathogenesis and antiviral therapies.