The common marmoset (Callithrix jacchus) is increasingly attractive for use as a non-human primate animal model in biomedical research. It has a relatively high reproduction rate for a primate, making it potentially suitable for transgenic modification. Although several attempts have been made to produce non-human transgenic primates, transgene expression in the somatic tissues of live infants has not been demonstrated by objective analyses such as polymerase chain reaction with reverse transcription or western blots. Here we show that the injection of a self-inactivating lentiviral vector in sucrose solution into marmoset embryos results in transgenic common marmosets that expressed the transgene in several organs. Notably, we achieved germline transmission of the transgene, and the transgenic offspring developed normally. The successful creation of transgenic marmosets provides a new animal model for human disease that has the great advantage of a close genetic relationship with humans. This model will be valuable to many fields of biomedical research.

Humanized mouse models that have received human cells or tissue transplants are extremely useful in basic and applied human disease research. Highly immunodeficient mice, which do not reject xenografts and support cell and tissue differentiation and growth, are indispensable for generating additional appropriate models. Since the early 2000s, a series of immunodeficient mice appropriate for generating humanized mice has been successively developed by introducing the IL-2Rc null gene (e.g., NOD/SCID/cc null and Rag2 null cc null mice). These strains show not only a high rate of human cell engraftment, but also generate well-differentiated multilineage human hematopoietic cells after human hematopoietic stem cell (HSC) transplantation. These humanized mice facilitate the analysis of human hematology and immunology in vivo. However, human hematopoietic cells developed from HSCs are not always phenotypically and functionally identical to those in humans. More recently, a new series of immunodeficient mice compensates for these disadvantages. These mice were generated by genetically introducing human cytokine genes into NOD/SCID/cc null and Rag2 null cc null mice. In this review, we describe the current knowledge of human hematopoietic cells developed in these mice. Various human disease mouse models using these humanized mice are summarized.

'Humanized mice' are anticipated to be a valuable tool for studying the human immune system, but the reconstituted human immune cells have not yet been well characterized. Here, we extensively investigated the differentiation and functions of human B and T cells in a supra-immunodeficient mouse strain, NOD/shi-scid/gammac(null) (NOG) reconstituted with CD34(+) hematopoietic stem cells obtained from umbilical cord blood. In these hu-HSC NOG mice, the development of human B cells was partially blocked, and a significant number of B-cell progenitors accumulated in the spleen. The mature CD19(+)IgM(+)IgD(+) human B cells of the hu-HSC NOG mice could produce IgG in vivo and in vitro by antigenic stimulation. In contrast, although human T cells with an apparently normal phenotype developed, most of them could neither proliferate nor produce IL-2 in response to antigenic stimulation by anti-CD3 and anti-CD28 antibodies in vitro. The positive selection of human T cells in the thymus was sufficiently functional, if not complete, and mainly mediated by mouse class II, suggesting that the human T cells lost their function in the periphery. We found that multiple mechanisms were involved in the T-cell abnormalities. Collectively, our results demonstrate that further improvements are necessary before humanized mice with a functional human immune system are achieved.

Recent advances in genome editing have facilitated the generation of nonhuman primate (NHP) models, with potential to unmask the complex biology of human disease not revealed by rodent models. However, their broader use is hindered by the challenges associated with generation of adult NHP models as well as the cost of their production. Here, we describe the generation of a marmoset model of severe combined immunodeficiency (SCID). This study optimized zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) to target interleukin-2 receptor subunit gamma (IL2RG) in pronuclear stage marmoset embryos. Nine of 21 neonates exhibited mutations in the IL2RG gene, concomitant with immunodeficiency, and three neonates have currently survived from 240 days to 1.8 years. Our approach demonstrates highly efficient production of founder NHP with SCID phenotypes, with promises of multiple pre-clinical and translational applications.

The development of animal models that mimic human allergic responses is crucial to study the pathophysiology of disease and to generate new therapeutic methodologies. Humanized mice reconstituted with human immune systems are essential to study human immune reactions in vivo and are expected to be useful for studying human allergies. However, application of this technology to the study of human allergies has been limited, largely because of the poor development of human myeloid cells, especially granulocytes and mast cells, which are responsible for mediating allergic diseases, in conventional humanized mice. In this study, we developed a novel transgenic (Tg) strain, NOD/Shi-scid-IL2rγnull (NOG), bearing human IL-3 and GM-CSF genes (NOG IL-3/GM–Tg). In this strain, a large number of human myeloid cells of various lineages developed after transplantation of human CD34+ hematopoietic stem cells. Notably, mature basophils and mast cells expressing FcεRI were markedly increased. These humanized NOG IL-3/GM–Tg mice developed passive cutaneous anaphylaxis reactions when administered anti–4-hydroxy-3-nitrophenylacetyl IgE Abs and 4-hydroxy-3-nitrophenylacetyl. More importantly, a combination of serum from Japanese cedar pollinosis patients and cedar pollen extract also elicited strong passive cutaneous anaphylaxis responses in mice. Thus, to our knowledge, our NOG IL-3/GM–Tg mice are the first humanized mouse model to enable the study of human allergic responses in vivo and are excellent tools for preclinical studies of allergic diseases.