A humanized mouse model is a broad term referring to a mouse engrafted with functional human genes, cells, or tissues. This type of model is usually used as an powerful in vivo model for preclinical study of human diseases. Humanized mouse models have become an important animal model for identifying how human genes impact development and disease.
Why Use Humanized Mice for Research?
The predominant goal of all biomedical research is to overcome human diseases. Due to medical ethics, we cannot initially test drugs with uncertain effects in the human body. Therefore, evaluating the drug safety and efficacy through animal models has become the best alternative. Mouse models have since become irreplaceable for the study of gene function and pathogenesis and have also accelerated the process of drug screening. Humanized mice widely serve as models in translational medicine, playing an important role in biological research, including regenerative medicine, transplantation, and immunology.
Humanized Mouse Models Applications
● Evaluating the efficacy of immunotherapy
● Pharmacodynamic experiments
● Prediction of clinical response
● Tumor immune research
● And more
How Are Humanized Mouse Models Made?
There are two primary methods of generating humanized mouse models, described below.
1) Transplantation of human cells or tissues into immunodeficient mice
Conventional humanized mouse models were established by transplanting human cells or tissues into immunodeficient mice. Due to the merits of high efficiency, economy, and relatively simple operation process, this method has been widely used as a preclinical experimental animal model in the research of human infectious diseases, cancer, regenerative medicine, transplantation, allergy, and immunity.
2) Insertion of human genes into the mouse genome using gene editing technology
applied in the research of human gene function, tumor immune drugs development, infectious diseases, preclinical evaluation of drugs and more. For example, by humanizing mouse genes related to immune checkpoints such as CTLA4 and PD1, humanized mice that can interact with anti-CTLA4 and PD1 humanized antibodies can be constructed - which provide an effective tool for preclinical screening and evaluation of antibody drugs.
In addition, with the rapid development of humanized antibody preparation in recent years, the construction of humanized mice by gene modification has become an intense area of antibody drug development research.
At present, there are several methods to construct humanized mouse models by gene editing, which are outlined below.
1. Pronuclear injection: Obtain humanize mouse via pronuclear injection (PNI), human gene was introduced into mice to express human gene;
2. Embryonic Stem (ES) cell targeting: Using mouse ES cell line, traditional gene targeting method can achieve the purpose of replacing mouse gene with human gene or inserting human gene;
3. CRISPR/Cas9 genome editing technology: Through pronuclear injection, to build humanized mouse model
The methods mentioned above have their own unique advantages and disadvantages, so it is necessary to identify the most suitable methods tailored to research needs and purposes in practical applications. The construction method of pronuclear injection is convenient, fast and economical, but due to the characteristics of random DNA insertion, the risk of endogenous gene interference and the possible inhibition of gene expression by insertion position effect may lead to uncertainty factors for future research. Due to its maturity and stability, traditional embryonic stem (ES) gene targeting technology has always been the gold standard for the preparation of gene modified mice. However, due to its high technical requirements and complex operation steps, the preparation timeline is relatively long. CRISPR/Cas9 technology has the advantages of simple design and operation, high efficiency of gene modification and no species restriction, which greatly advances the development of humanized animal models. Of course, due to the existence of off target effect, and the risk of complex modification effect is difficult to control, the application of this technology is also limited to a certain extent.
How Can Cyagen Support Humanized Mouse Models Development?
With more than 15 years’ experience in genetic engineering, Cyagen offers a complete range of services to generate genetically modified humanized mice. Compared to the traditional ES cell targeting method, Cyagen’ proprietary TurboKnockout® gene targeting method developed two innovations:
● Eliminates the unpredictability of germline transmission (GLT) with our super competent ESC line that generates 100% ESC-derived founder mice rather than chimeras.
● Self-removing selection cassette circumvents the need to breed to Flp deleter mice.
These innovations eliminate at least two generations of breeding, shortening production time by 4-6 months as compared to the industry standard. For conditional knockouts, it may be possible to breed founders directly to your tissue-specific Cre mice.
Cyagen’s TurboKnockout® gene targeting service, a proprietary optimization of traditional ESC-mediated targeting techniques, enables more efficient and stable gene integration for the development of humanized mouse models.
Additional Animal Models & Supporting Services
In addition to animal model generation, Cyagen has established a range of supporting services, such as animal breeding, embryo/sperm cryopreservation, histology, and transcriptome profiling. Outsourcing these services to Cyagen is a more cost-effective way of conducting your research. All these services are performed by experienced specialists following standardized procedures, so we can guarantee delivery of high quality services and data acquisition with unbeatable price and turnaround.