Top Questions… Isn't there a high rate of clinical failure for drugs tested in mice? Why do we still need to test on mice when we can just use computers? Why do we still need mouse models if human patients already provide large amounts of medical data? What's more effective: human or animal studies? Why are mice excellent models for humans? What is the future of mouse-based research? Why mouse genetics? What is being done to improve the medical yield from mouse-based research? How did the lab mouse come to be? What is a mouse model? How can research in mice lead to new ways to prevent and treat disease? What does the mouse teach us that we can’t learn from yeast, worms, insects and fish? What regulatory bodies govern what we can do with mice? Why do we need mice for medical research? How can the public be assured that researchers are using mice in a responsible way? Why do we need mice when we can test drugs on human cells and tissues?

What is a mouse model?

The mouse is the foremost mammalian model for studying human disease and human health. The mouse is small, making it an economical choice, and it also breeds very well. Scientists have amassed tremendous knowledge about mouse physiology, anatomy, and its genes, stemming from more than 100 years of working with them. More importantly, we can manipulate mouse genes; the mouse is among the first mammalian species to have its genes modified with molecular tools.

The ability to manipulate the mouse genome is what makes the mouse so relevant today. Now that we've sequenced both the human and mouse genomes, we know their usual molecular constitutions and how the sequences vary between individuals and between the two species. Even between two healthy people, there can be millions of small sequence and structure differences that help define who those people are as individuals.

Therefore, the remaining challenges in genomics remain formidable. Researchers are hard at work investigating what effects the millions of variations present in each genome have for health and disease. And while we cannot change our own genomes, we can change those of mice. Making small tweaks to individual mouse genes or even sequences within a specific gene allows scientists see what happens as a result. Moving forward, the mouse is essential for learning more about genomics and about ourselves.

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Why JAX?

JAX pioneered the use of mice in disease research, and its mice and research program have contributed to important medical breakthroughs ever since. Throughout, JAX has spearheaded the drive for increasing the accuracy and relevance of mouse-based biomedical research. It is imperative that mice are fully characterized for both genetics and traits and that the correct strain(s) are used for each research project.

Recent progress has made mouse models more useful and effective for biomedical research, not less. JAX has led the development of advanced mouse populations that model human genetic variability, providing nuanced results that show the range of responses seen in humans, such as to a new drug. Detailed information about human genetics can also be brought back to research, allowing scientists to precisely develop mouse models that have exactly the same genetic changes seen in patients. JAX bridges the gap between patients and mouse-based research, accelerating discovery and driving medical innovation.

Mice are the most commonly used animal model for studying human disease, and for many good reasons:

• Mice are biologically very similar to humans and get many of the same diseases, for the same genetic reasons.
• Mice can be genetically manipulated to mimic virtually any human disease or condition. With modern sequencing and genomic engineering technologies, the precise mutation(s) underlying human disease can be introduced into mice, yielding more accurate and useful disease research data.
• Mice can be inbred to yield genetically identical strains. This uniformity allows for more accurate and repeatable experiments. The Jackson Laboratory now maintains more than 9,000 genetically defined strains of mice.
• Mice have an accelerated lifespan, with one mouse year equaling about 30 human years. Therefore, their entire life cycle can be studied within only two or three years.
• Mice are well understood because they have been used in biomedical research for nearly a century. The Jackson Laboratory began using and developing mice in 1929.
• Mice are a cost-effective and efficient research tool. They are small, they reproduce quickly, and they are relatively easy to handle and transport.

The mouse in biomedical research

Many diseases can be modeled through the alteration of a specific gene central to a normal biological process. Thousands of disease models that have either arisen spontaneously in The Jackson Laboratory production colonies or that have been genetically engineered are available from The Jackson Laboratory.

Practically, mice are small, have a short generation time and an accelerated lifespan (one mouse year equals about 30 human years), keeping the costs, space and time required to perform research manageable. In addition to these clear benefits, the greatest advantages associated with using the mouse are:

• Ability to genetically engineer new strains, including mice that can host patient tumors or specific gene mutations or a human immune system
• Availability of pure, inbred lines
• Opportunity to identify disease-causing gene mutations
• Platform for identifying modifying genes and background effects.
• Mouse models play an essential role in the drug discovery process. In preclinical trials, mouse models are key to demonstrating the metabolism and absorption, general safety and even efficacy of new medicines. The FDA insists that drug trial designs rely heavily on clinical measures of efficacy. A mouse strain with relevant disease symptoms provides a primary, effective and efficient model that is vital to the process of drug discovery.

Mice are the model of choice not just because they are strikingly similar to humans at the genomic level, but also because the pathophysiology of disease in mice is similar to that of humans. Mice are a cost-effective and efficient tool to speed research and drug testing.

These combinations of features provide researchers with a uniquely powerful tool for understanding the mechanisms of human disease and testing of novel drug therapies.