Humanized mouse

A humanized mouse is a mouse carrying functioning human genes, cells, tissues, and/or organs. Humanized mice are commonly used as small animal models in biological and medical research for human therapeutics.

A humanized mouse or a humanized mouse model is one that has been xenotransplanted with human cells and/or engineered to express human gene products, so as to be utilized for gaining relevant insights in the  in vivo context for understanding of human-specific physiology and pathologies.[1] A lot of our knowledge about several human biological processes has been obtained from studying animal models like rodents and non-human primates. In particular, small animals such as mice are advantageous in such studies owing to their small size, brief reproductive cycle, easy handling and due to the genomic and physiological similarities with humans; moreover, these animals can also be genetically modified easily. Nevertheless, there are several incongruencies of these animal systems with those of the humans, especially with regard to the components of the immune system. To overcome these limitations and to realize the full potential of animal models to enable researchers to get a clear picture of the nature and pathogenesis of immune responses mounted against human-specific pathogens, humanized mouse models have been developed. Such mouse models have also become an integral aspect of pre-clinical biomedical research.[2]

History

The discovery of the athymic mouse, commonly known as the nude mouse, and that of the SCID mouse were major events that paved the way for humanized mice models. The first such mouse model was derived by backcrossing C57BL/Ka and BALB/c mice, featuring a loss of function mutation in the PRKDC gene. The PRKDC gene product is necessary for resolving breaks in DNA strands during the development of T cells and B cells. Dysfunctional PRKDC gene leads to impaired development of T and B lymphocytes which gives rise to severe combined immunodeficiency (SCID). Inspite of the efforts in developing this mouse model, poor engraftment of human hematopoietic stem cells (HSCs) was a major limitation that called for further advancement in the development humanized mouse models.[3] The next big step in the development of humanized mice models came with transfer of the scid mutation to a non-obese diabetic mouse. This resulted in the creation of the NOD-scid mice which lacked T cells, B cells, and NK cells. This mouse model permitted for a slightly higher level of human cell reconstitution. Nevertheless, a major breakthrough in this field came with the introduction of the mutant interleukin 2 receptor α (IL2rα) gene in the NOD-scid model. This accounted for the creation of the NOD-scid-γcnull mice (NSG or NOG) models which were portrayed to have defective interleukins IL-2, IL-4, IL-7, IL-9, and IL-15. Researchers evolved this NSG model by knocking out the RAG1 and RAG2 genes (recombination activation genes), resulting into the RAGnull version of the NSG model that was devoid of major cells of the immune system including the natural killer cells, B lymphocytes and T lymphocytes, macrophages and dendritic cells, causing the greatest immunodeficiency in mice models so far. The limitation with this model was that it lacked the human leukocyte antigen. In accordance to this limitation, the  human T cells when engrafted in the mice, failed to recognize human antigen-presenting cells, which consequated in defective immunoglobulin class-switching and improper organization of the  secondary lymphoid tissue.[4]

To circumvent this limitation, the next development came with the introduction of transgenes encoding for HLA I and HLA II in the NSG RAGnull model that enabled buildout of human T-lymphocyte repertoires as well as the respective immune responses.[5]

Types

Engrafting an immunodeficient mouse with functional human cells can be achieved by intravenous injections of human cells and tissue into the mouse. This section highlights the various humanized mice models developed using the different methods.

Hu-PBL-scid model

This model is developed by intravenously injecting human PBMCs into immunodeficient mice. The peripheral blood mononuclear cells to be engrafted into the model are obtained from consented adult donors. The advantages associated with this method are that it is comparatively an easy technique, the model takes relatively less time to get established and that the model exhibits  functional T memory cells.[6] It is particularly very effective for modelling graft vs. host disease.[5] The model lacks engraftment of B lymphocytes and myeloid cells. Other limitations with this model are that it is suitable for use only in short-term experiments (<3 months) and the possibility that the model itself might develop graft vs. host disease.[5]

Hu-SRC-scid model

Hu-SRC-scid mice are developed by engrafting CD34+ human hematopoietic stem cells into immunodeficient mice. The cells are obtained from human fetal liver, bone marrow or from blood derived from the umbilical cord,[7] and engrafted via intravenous injection. The advantages of this model are that it offers multilineage development of hematopoietic cells, generation of a naïve immune system, and if engraftment is carried out by intrahepatic injection of newborn mice within 72 hours of birth, it can lead to enhanced human cell reconstitution. Nevertheless, limitations associated with the model are that it takes a minimum of 10 weeks for cell differentiation to occur, it harbors low levels of human RBCs, polymorphonuclear leukocytes, and megakaryocytes.[5]

BLT (bone marrow/liver/thymus) model

The BLT model is constituted with human HSCs, bone marrow, liver, and thymus. The engraftment is carried out by implantation of liver and thymus under the kidney capsule and by transplantation of HSCs obtained from fetal liver. The BLT model has a complete and totally functional human immune system with HLA-restricted T lymphocytes. The model also comprises a mucosal system that is similar to that of humans. Moreover, among all models the BLT model has the highest level of human cell reconstitution.[8]

However, since it requires surgical implantation, this model is the most difficult and time-consuming to develop. Other drawbacks associated with the model are that it portrays weak immune responses to xenobiotics, sub-optimal class switching and may develop GvHD.[5]

Established models for human diseases

Several mechanisms underlying human maladies are not fully understood. Utilization of humanized mice models in this context allows researchers to determine and unravel important factors that bring about the development of several human diseases and disorders falling under the categories of  infectious disease, cancer, autoimmunity, and GvHD.

Infectious diseases

Among the human-specific infectious pathogens studied on humanized mice models, the human immunodeficiency virus has been successfully studied.[5] Besides this, humanized models for studying Ebola virus,[9] Hepatitis B,[10] Hepatitis C,[11] Kaposi’s sarcoma-associated herpes virus,[12] Leishmania major,[13] malaria,[14] and tuberculosis [15] have been reported by various studies.

NOD/scid mice models for dengue virus [16] and varicella-zoster virus,[17] and a Rag2null𝛾cnull model for studying influenza virus [18] have also been developed.

Cancers

On the basis of the type of human cells/tissues that have been used for engraftment, humanized mouse models for cancer can be classified as patient-derived xenografts or cell line-derived xenografts.[19] PDX models are considered to retain the parental malignancy characteristics at a greater extent and hence these are regarded as the more powerful tool for evaluating the effect of anticancer drugs in pre-clinical studies.[19][20] Humanized mouse models for studying cancers of various organs have been designed. A mouse model for  the study of breast cancer has been generated by the intrahepatic engraftment of SK-BR-3 cells in NSG mice.[21] Similarly, NSG mice intravenously engrafted with patient-derived AML cells,[22] and those engrafted (via subcutaneous, intravenous or intra-pancreatic injections) with patient-derived pancreatic cancer tumors[23] have also been developed for the study of leukemia and pancreatic cancer respectively. Several other humanized rodent models for the study of cancer and cancer immunotherapy have also been reported.[24]

Autoimmune diseases

Problems posed by the differences in the human and rodent immune systems have been overcome using a few strategies, so as to enable researchers to study autoimmune disorders using humanized models.  NSG mice engrafted with PBMCs and administered with myelin antigens in Freund’s adjuvant, and antigen-pulsed autologous dendritic cells have been used to study multiple sclerosis.[25] Similarly, NSG mice engrafted with hematopoietic stem cells and administered with pristane have been used for studying lupus erythematosus.[26]

See also

References
  1. Stripecke R, Münz C, Schuringa JJ, Bissig KD, Soper B, Meeham T, et al. (July 2020). "Innovations, challenges, and minimal information for standardization of humanized mice". EMBO Molecular Medicine. 12 (7): e8662. doi:10.15252/emmm.201708662. PMC 7338801. PMID 32578942.
  2. Walsh NC, Kenney LL, Jangalwe S, Aryee KE, Greiner DL, Brehm MA, Shultz LD (January 2017). "Humanized Mouse Models of Clinical Disease". Annual Review of Pathology. 12 (1): 187–215. doi:10.1146/annurev-pathol-052016-100332. PMC 5280554. PMID 27959627.
  3. Ito R, Takahashi T, Katano I, Ito M (May 2012). "Current advances in humanized mouse models". Cellular & Molecular Immunology. 9 (3): 208–14. doi:10.1038/cmi.2012.2. PMC 4012844. PMID 22327211.
  4. Bosma GC, Custer RP, Bosma MJ (February 1983). "A severe combined immunodeficiency mutation in the mouse". Nature. 301 (5900): 527–30. Bibcode:1983Natur.301..527B. doi:10.1038/301527a0. PMID 6823332. S2CID 4267981.
  5. Yong KS, Her Z, Chen Q (August 2018). "Humanized Mice as Unique Tools for Human-Specific Studies". Archivum Immunologiae et Therapiae Experimentalis. 66 (4): 245–266. doi:10.1007/s00005-018-0506-x. PMC 6061174. PMID 29411049.
  6. Tary-Lehmann M, Saxon A, Lehmann PV (November 1995). "The human immune system in hu-PBL-SCID mice". Immunology Today. 16 (11): 529–33. doi:10.1016/0167-5699(95)80046-8. PMID 7495490.
  7. Pearson T, Greiner DL, Shultz LD (May 2008). "Creation of "humanized" mice to study human immunity". Current Protocols in Immunology. Chapter 15 (1): Unit 15.21. doi:10.1002/0471142735.im1521s81. PMC 3023233. PMID 18491294.
  8. Karpel ME, Boutwell CL, Allen TM (August 2015). "BLT humanized mice as a small animal model of HIV infection". Current Opinion in Virology. Animal models for viral diseases / Oncolytic viruses. 13: 75–80. doi:10.1016/j.coviro.2015.05.002. PMC 4550544. PMID 26083316.
  9. Lüdtke A, Oestereich L, Ruibal P, Wurr S, Pallasch E, Bockholt S, et al. (April 2015). "Ebola virus disease in mice with transplanted human hematopoietic stem cells". Journal of Virology. 89 (8): 4700–4. doi:10.1128/JVI.03546-14. PMC 4442348. PMID 25673711.
  10. Bility MT, Cheng L, Zhang Z, Luan Y, Li F, Chi L, et al. (March 2014). "Hepatitis B virus infection and immunopathogenesis in a humanized mouse model: induction of human-specific liver fibrosis and M2-like macrophages". PLOS Pathogens. 10 (3): e1004032. doi:10.1371/journal.ppat.1004032. PMC 3961374. PMID 24651854.
  11. Bility MT, Zhang L, Washburn ML, Curtis TA, Kovalev GI, Su L (September 2012). "Generation of a humanized mouse model with both human immune system and liver cells to model hepatitis C virus infection and liver immunopathogenesis". Nature Protocols. 7 (9): 1608–17. doi:10.1038/nprot.2012.083. PMC 3979325. PMID 22899330.
  12. Wang LX, Kang G, Kumar P, Lu W, Li Y, Zhou Y, et al. (February 2014). "Humanized-BLT mouse model of Kaposi's sarcoma-associated herpesvirus infection". Proceedings of the National Academy of Sciences of the United States of America. 111 (8): 3146–51. Bibcode:2014PNAS..111.3146W. doi:10.1073/pnas.1318175111. PMC 3939909. PMID 24516154.
  13. Wege AK, Florian C, Ernst W, Zimara N, Schleicher U, Hanses F, et al. (2012-07-24). "Leishmania major infection in humanized mice induces systemic infection and provokes a nonprotective human immune response". PLOS Neglected Tropical Diseases. 6 (7): e1741. doi:10.1371/journal.pntd.0001741. PMC 3404120. PMID 22848771. S2CID 7657105.
  14. Amaladoss A, Chen Q, Liu M, Dummler SK, Dao M, Suresh S, et al. (2015-06-22). "De Novo Generated Human Red Blood Cells in Humanized Mice Support Plasmodium falciparum Infection". PLOS ONE. 10 (6): e0129825. Bibcode:2015PLoSO..1029825A. doi:10.1371/journal.pone.0129825. PMC 4476714. PMID 26098918. S2CID 543860.
  15. Calderon VE, Valbuena G, Goez Y, Judy BM, Huante MB, Sutjita P, et al. (2013-05-17). "A humanized mouse model of tuberculosis". PLOS ONE. 8 (5): e63331. Bibcode:2013PLoSO...863331C. doi:10.1371/journal.pone.0063331. PMC 3656943. PMID 23691024. S2CID 17215038.
  16. Frias-Staheli N, Dorner M, Marukian S, Billerbeck E, Labitt RN, Rice CM, Ploss A (February 2014). "Utility of humanized BLT mice for analysis of dengue virus infection and antiviral drug testing". Journal of Virology. 88 (4): 2205–18. doi:10.1128/JVI.03085-13. PMC 3911540. PMID 24335303.
  17. Moffat JF, Stein MD, Kaneshima H, Arvin AM (September 1995). "Tropism of varicella-zoster virus for human CD4+ and CD8+ T lymphocytes and epidermal cells in SCID-hu mice". Journal of Virology. 69 (9): 5236–42. doi:10.1128/jvi.69.9.5236-5242.1995. PMC 189355. PMID 7636965.
  18. Zheng J, Wu WL, Liu Y, Xiang Z, Liu M, Chan KH, et al. (2015-08-18). "The Therapeutic Effect of Pamidronate on Lethal Avian Influenza A H7N9 Virus Infected Humanized Mice". PLOS ONE. 10 (8): e0135999. Bibcode:2015PLoSO..1035999Z. doi:10.1371/journal.pone.0135999. PMC 4540487. PMID 26285203. S2CID 10461525.
  19. Tian H, Lyu Y, Yang YG, Hu Z (2020). "Humanized Rodent Models for Cancer Research". Frontiers in Oncology. 10. doi:10.3389/fonc.2020.01696. ISSN 2234-943X. S2CID 221589508.
  20. Hausser HJ, Brenner RE (July 2005). "Phenotypic instability of Saos-2 cells in long-term culture". Biochemical and Biophysical Research Communications. 333 (1): 216–22. doi:10.1016/j.bbrc.2005.05.097. PMID 15939397.
  21. Wege AK, Schmidt M, Ueberham E, Ponnath M, Ortmann O, Brockhoff G, Lehmann J (2014-05-08). "Co-transplantation of human hematopoietic stem cells and human breast cancer cells in NSG mice: a novel approach to generate tumor cell specific human antibodies". mAbs. 6 (4): 968–77. doi:10.4161/mabs.29111. PMC 4171030. PMID 24870377. S2CID 34234807.
  22. Her Z, Yong KS, Paramasivam K, Tan WW, Chan XY, Tan SY, et al. (October 2017). "An improved pre-clinical patient-derived liquid xenograft mouse model for acute myeloid leukemia". Journal of Hematology & Oncology. 10 (1): 162. doi:10.1186/s13045-017-0532-x. PMC 5639594. PMID 28985760.
  23. Her Z, Yong KS, Paramasivam K, Tan WW, Chan XY, Tan SY, et al. (October 2017). "An improved pre-clinical patient-derived liquid xenograft mouse model for acute myeloid leukemia". Journal of Hematology & Oncology. 10 (1): 162. doi:10.1186/s13045-017-0532-x. PMID 28985760. S2CID 25506701.
  24. Chen Q, Wang J, Liu WN, Zhao Y (July 2019). "Cancer Immunotherapies and Humanized Mouse Drug Testing Platforms". Translational Oncology. 12 (7): 987–995. doi:10.1016/j.tranon.2019.04.020. PMC 6529825. PMID 31121491.
  25. Zayoud M, El Malki K, Frauenknecht K, Trinschek B, Kloos L, Karram K, et al. (September 2013). "Subclinical CNS inflammation as response to a myelin antigen in humanized mice". Journal of Neuroimmune Pharmacology. 8 (4): 1037–47. doi:10.1007/s11481-013-9466-4. PMID 23640521. S2CID 503830.
  26. Gunawan M, Her Z, Liu M, Tan SY, Chan XY, Tan WW, et al. (November 2017). "A Novel Human Systemic Lupus Erythematosus Model in Humanised Mice". Scientific Reports. 7 (1): 16642. Bibcode:2017NatSR...716642G. doi:10.1038/s41598-017-16999-7. PMC 5709358. PMID 29192160. S2CID 5604139.

Further reading
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.