Knockout Mouse Models

Knockout mice are defined as having a certain gene of interest made inoperative, or "knocked out." Often referred to as KO mice, they are used to study gene function and to validate new drugs and treatments. Charles River delivers high-quality, validated knockout mouse models for generating consistent study data which makes research reproducible, and lowers overall study costs. Our end-to-end commitment ensures adherence of project timelines, confidentiality, exclusivity of intellectual property, breeding under VAF Plus® (SOPF) standards, and secure global delivery.

Webinar Series:
Transgenic Mouse and Rat Model Creation

Genome editing for the creation of knockout miceLearn more about CRISPR-Cas9* for genome editing, animal model creation, gene therapy, and modelling human disease by watching our webinar series.  
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Our scientific team works with industry partners who are leaders in the field of functional genomics and molecular engineering. Our combined in vitro and in vivo expertise provides the optimal environment for creating, characterizing, preserving, and distributing your mice.


Types of Knockout Mouse Models

  • Constitutive Knockout Mice

    This model is engineered to carry an inoperative gene. Usually, inactivation of the gene is achieved by the deletion (partial or total) of its sequence, and it is nonfunctional in the entire animal.

  • Conditional Knockout Mice

    These knockout mice allow the deletion of a gene in a tissue- and/or time-specific manner. Often, the conditional KO mouse is achieved through the Cre-lox system. Instead of deleting the critical sequence, it is flanked by loxP sites (termed a floxed sequence). Cre recombinase deletes the sequence between two loxP sites. An inducible or tissue-specific Cre is used to knockout gene function in only that tissue.

  • RNAi Knockout Mice

    RNA interference can reduce the expression of a target gene, without deleting it. Typically this is combined with conditional and/or inducible approaches to reduce expression of the target only under certain conditions in adult animals.

Customized Animal Models

See how the gene editing system known as CRISPR-Cas9* is transforming how we create animal models of disease.

  • Video Transcript
    00:12 There are thousands of genetically modified models. The human genome has about 20,000 protein coding genes, and there are sponsored efforts to knock out every one of those genes. It's estimated that about half of mice and rats used in research are genetically modified. To make a transgenic mouse, it used to take scientists about 12 to 18 months using the traditional techniques. With the latest techniques such as the CRISPR-Cas9 technology, it takes anywhere between three months to nine months.
    01:15 CRISPR technology is a way where we can program a specific enzyme to cut anywhere in the genome. We can effectively cut and repair, and by doing so, it will create random mutations, or if we give it an actual donor template, it can incorporate that gene into the genome.
    01:39 So Mirimus was formed in 2010. We entered the CRISPR arena shortly after the first publications came out in 2012. We had to jump on this technology because it was so exciting. I mean, the ability to cut the genome and modify it is a game changing in terms of model creation.
    02:02 Charles River began partnering with Mirimus a couple of years ago, and the reason for the collaboration is that we have a complimentary set of core competencies. Our partners at Mirimus are experts in bioinformatics and genome editing technologies, and at Charles River, we have expertise in embryology and production breeding. By merging those two skill sets, we have created a unique service offering in which we bring model creation to our clients on an industrial scale.
    02:36 So the types of models that you can create very rapidly with CRISPR are knockout models. You can cut two places in the genome and that gene will bind itself together and repair. And so by actually cutting in two places you've excised the gene.
    02:53 If you actually want to create a knockin model, you can make a cut and actually deliver a template, and that template will be duplicated into the genome, thereby allowing you to modify and make any sort of designer gene that you would like.
    03:07 The biggest challenges with CRISPR are that it's very easy to make a gene knockout. It's much, much more difficult to modify a gene and having a gene knocked in, so we're still trying to understand how it works precisely, so that we can get that to work much more efficiently.
    03:25 CRISPR is moving at a speed unseen before. In every few weeks, you see more hundreds of papers coming out. I think we need to definitely keep up the speed in terms of trying to understand how CRISPR works to get it to work almost perfectly.
    03:46 We do have to proceed cautiously. The side effects of editing a human genome may not be visible for many, many years, possibly even generations. Being careful is key, but proceeding is certainly justified seeing the benefits that this technology has brought.
    04:10 I do believe that, in our lifetime, we will see diseases being cured. We should continue to use this technology to identify cure for diseases. And as long as we proceed with safety and ethics in mind, we should harness the power of this technique.


There are thousands of genetically modified animals and the CRISPR-Cas9 system makes it possible to create and maintain customized knockout mice to use for drug development and testing. 

Find out more


Frequently Asked Questions (FAQs) About Knockout Mice


Further Insights

  • The Science of Controlling CRISPR

    With technologies like CRISPR gene editing accelerating at a rapid pace, what was once thought to be impossible to achieve with mice may become reality sooner than we ever imagined. The challenge will be to fully understand and control these new mouse model creation tools. For example: how does one limit off-target effects? What do we know about circular permutation, or inhibiting CRISPR with anti-CRISPRs? Read the full story

  • The CRISPR Potential in Accelerating Drug Development

    CRISPR's comparative ease of use is expected to contribute to the development of more multifaceted cellular assays with improved predictability for drug therapies. Some of the benefits include reduced attrition rates of compounds and improved target validation. 
    Read the full story


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*CRISPR-Cas9 used under licenses to granted and pending US and international patents from The Broad Institute and ERS Genomics Limited.