Humanized mice, mice expressing human genes produced via transgenesis, are involved in studying humans’ hematopoiesis and immunological pathways. These mice are engrafted with immunocytes (lymphocytes) or hematopoietic stem cells (HSC) or tissues. For mouse engrafting with human tissue, fetal thymus and HSC are used. During production of engrafted mouse, mature T cells are observed following exposure to leukocyte antigenic peptides of humans. Humanized mice have antibodies genes that lead to the production of various immunoglobulins of humans, and these antibodies are known as humanized mouse antibodies.
In 1983, the first humanized mice were developed that have peripheral blood lymphocytes (PBL) of humans, and the mouse model was named huPBL-model. It was created by intraperitoneal injection of human peripheral blood lymphocytes into the irradiated immunodeficient mouse.
| Humanized mice | Genetic Background | Reference |
| SCID | CB-17 | (Mosier et al., 1988) |
| NOD-SCID | NOD | (Shultz et al., 1995) |
| BRG | Balb/c | (Mazurier et al., 1999) |
| NOG | NOD | (Ito et al., 2002) |
| NSG | NOD | (Ishikawa et al., 2005) |
| NRG | NOD | (Pearson et al., 2008) |
| BRGS | Balb/c | (Legrand et al., 2011) |
| SRG | Balb/c X 129 | (De La Rochere et al., 2018) |
| B6RGS | C57BL/6 | (Shultz et al., 2019) |
| B6RG-CD47 | C57BL/6 | (Martinov et al., 2021) |
The Necessity of Human Antibody For Humanized Mice And The Major Breakthroughs
- Disadvantages in clinical application of murine antibody
Monoclonal antibodies of mouse origin are very specific to a single antigen and may not be effective against a pathogen due to mutation(s) in that specific antigen. They are not involved in hemagglutination (no cross-linkage with antigen) due to slight alterations at the antibody binding site.
- Chimeric antibody technology
The antibodies were generated as a result of genetic engineering, in which the constant region of immunoglobulin of human origin joined with the variable region of antibodies of mouse hybridoma origin. These chimeric antibodies are the first step towards more humanization. Chimeric antibodies are used to treat patients with worsened multiple myeloma and hematological malignancies. These are cheaper than a fully humanized mouse and more useful for initial biotherapeutic research. Notably, species-based chimeric antibodies minimize the risk of anti-species reactions in animal models.
- Phage display technology
A bacteriophage is used to study the DNA-protein, protein-peptide, and protein-protein interactions, and a connection is generated between the encoding genome and protein. In phage display technology, epitope mapping is performed, and ligands separated from these phage libraries are useful for drug design, therapeutic validation, and vaccine development.
The Current Situation Of Genetically Humanized Mice for Antibody Research
- Challenges
Following the engraftment with HSC or PBL, mature B-lymphocytes may be impaired, production of immunoglobulins lowered, and MHC class I and class II alleles restrict T-cell generation. Engraftment of mice with mature T-lymphocytes leads to Graft Versus Host Disease (GVHD) and there is human host-specific pathogen involvement. Further, there is poor growth of human cancer cell engraft and lack of human immune cell trafficking.
- Advantages compared with the previous technology
They are effective in evaluating the immunotherapeutic efficacy, pharmacodynamic experiments, clinical response estimation, and immunological research specifically concerning tumors. The generation of antigen-specific antibodies is effective to overcome the antibodies resistance and further rationalized the use of antibodies against various deadly pathogens. The affinity and efficacy of humanized mice antibodies are comparatively higher than antibodies obtained via in-vitro recombinant technology.
- Achievements Using Humanized Mouse Models
Humanized mouse model helps to overcome antimicrobial-resistant, and pathogen specific therapy is performed. It also leads to development of antibodies against numerous deadly disease like anti-HIV antibodies, anti-RSV antibodies, anti-SARS2 antibodies, etc.
One such novel mouse, called RenMab, has receptor-binding domain (RBD)-blocking antibodies with four different epitopes. With the help of humanized mice, the rational antibodies cocktail was produced against COVID-19 that has proven immunogenic and hACE2 blocking activity.
Cyagen is the leading provider of custom genetically humanized mice for research, which can be designed to your project requirements. With their proprietary TurboKnockout® service, Cyagen is able to generate large fragment knock-in (LFKI) humanized mouse models that express human antibody genes up to 300kb using RMCE and BAC technology.
Cyagen’s humanized mice projects are all AAALAC-accredited and OLAW assured.
For more information, please visit Cyagen at: https://www.cyagen.com/us/en/.