Why do we use mice?

Over eight out of ten animals used in research at Cambridge are mice. Their short life span and fast reproductive rate make it possible to investigate biological processes in many areas, at all stages of the life cycle.

The mouse makes an excellent model for human disease because the organisation of their DNA and their gene expression is similar to humans, with ninety-eight percent of human genes having a comparable gene in the mouse. They have similar reproductive and nervous systems to humans, and suffer from many of the same diseases such as obesity, cancer and diabetes.

It is possible to manipulate the DNA of mice either through cross-breeding or using techniques that ‘knock out’ certain genes, or edit their genes using recently-developed CRISPR-Cas techniques. This enables us to study novel genes of interest in the specific areas of the body without the need for generating new GM mice, which will dramatically reduce the number of animals needed to perform research.  Manipulating their genes can lead the mice to develop other diseases that do not naturally affect them. As a result research on mice has helped the understanding of both human physiology and the causes of disease.

Information adapted from AnimalResearch.info

What do we study?

Understanding abnormalities in embryo development

Our researchers have used mice to model aneuploidy, where some cells in the embryo contain an abnormal number of chromosomes. Normally, each cell in the human embryo should contain 23 pairs of chromosomes, but some can carry multiple copies of chromosomes, which can lead to developmental disorders. For example, children born with three copies of chromosome 21 will develop Down’s syndrome.

Pregnant mothers – particularly older mothers, whose offspring are at greatest risk of developing such disorders – are offered tests to predict the likelihood of genetic abnormalities. Until very recently, little was understood about the fate of embryos containing abnormal cells and about the fate of these abnormal cells within the developing embryos.

Our researchers developed a mouse model of aneuploidy by mixing 8-cell stage mouse embryos in which the cells were normal with embryos in which the cells were abnormal and showed that the embryo has an amazing ability to correct itself. This means that even when early indications suggest a child might have a birth defect because there are some abnormal cells in its embryonic body, this isn’t necessarily the case.

See also: Early-stage embryos with abnormalities may still develop into healthy babies

Finding a treatment for heart disease

In 2020, Cambridge researchers trying to turn off a gene that allows cancers to spread made a surprising U-turn. By making the gene overactive and functional in the hearts of mice, they triggered heart cell regeneration.Since adult hearts cannot usually repair themselves once damaged, harnessing the power of this gene represents major progress towards the first curative treatment for heart disease. 

See also: Switching on a key cancer gene could provide first curative treatment for heart disease

Finding a vaccine against COVID-19

In 2020, Cambridge scientists began work to find a vaccine against COVID-19. Mice are an important part of vaccine research: their physiology and immune systems are similar enough to ours to enable researchers to minimise the risk to humans taking part in clinical trials. 

See also: Cambridge research team working towards vaccine against COVID-19