The Crick has published statistics on the number of animals used in research in 2025, as part of the institute’s commitment to openness in animal research.
The latest national figures are reported in the Home Office’s statistics of scientific procedures on living animals in 2025. 216,508 of overall procedures were carried out at the Crick last year and more than 99% of procedures involved mice or fish.
This number reflects the expansion of research programmes where there is still no viable alternative to studying biology in a whole organism. At the Crick, this includes work using mouse models to understand how cancers develop and respond to treatment, studies of the immune system that track how cells across the body behave during infection, and research into neurodegenerative diseases, where interactions between different cell types can only be observed in living tissue. Animal models are also essential for developing and testing potential therapies before they reach clinical trials.
In 2025, there was a 10% increase in the number of project licences with authority to use of animals in research at the Crick. The number of animals used reflects the Crick's role as a national discovery research institute. As well as supporting the work of its own scientists, Crick facilities enable research led by partners and collaborators including at its founding universities. The Crick is helping to minimise animal use by enabling access to expert shared animal resources, improving data accuracy and refining experimental procedures.
Alongside this, the Crick continues to develop different platforms for advanced alternative methods and continually seeks opportunities to replace animal use wherever possible.
Sarah Hart-Johnson, Director of the Crick’s Biological Research Facility said: “These statistics reflect both the scale and complexity of the science taking place across the institute and the important work we support through collaborations with university partners. As a national biomedical research institute, our facilities and expertise enable research that extends far beyond our own laboratories.
“In areas where whole biological systems need to be understood or complex diseases modelled, animals remain an essential part of research. Their use is closely integrated with complementary non-animal methods and follows rigorous scientific and ethical review.
“Reducing reliance on animals is fundamental in the way we conduct research, ensuring our science remains robust and impactful. Our scientists are leaders in developing and sharing new approaches, including organoids, organs-on-chips, stem cell-based models and computational methods.”
In a recent study, researchers at the Crick and Imperial College London explored how the immune response to respiratory viruses in mice may hold the answers to inhibiting the spread of breast cancer.
The team investigated the effects of recent infection with respiratory syncytial virus (RSV), a common cause of coughs and colds, on the ability of cancer to spread to the lungs.
To mimic the spread of breast cancer cells to the lungs, they introduced breast cancer cells into mice that had recently experienced RSV infection, and looked to see if they spread to the lung. These mice developed fewer lung tumours than mice that hadn’t previously experienced RSV infection.
They showed that the immune response to the infection reshaped the lung environment, effectively stopping cancer cells from taking hold.
This is an important finding that could help scientists develop new ways to intervene before a cancer spreads.
Crick researchers are finding new ways to model infection and immune response by developing advanced alternative methodologies that can provide detailed, human-relevant insights while reducing reliance on animals.
Scientists in the Host-Pathogen Interactions in Tuberculosis Laboratory developed lab-grown ‘mini lungs’ that capture key features of human lung biology, allowing scientists to observe how infection progresses and how cells respond in real time.
They used human induced pluripotent stem cells, which can become any cell in the body, to make the cells lining the lung air sacs (alveolar epithelial cells) and blood vessels (vascular endothelial cells), grown either side of a membrane to recreate an air sac barrier. Then then imposed rhythmic three-dimensional stretching forces to mimic the motion of breathing and stimulate the formation of short finger-like structures called microvilli, a key feature of alveolar epithelial cells to increase surface area for lung functions.
The team found that these models could reproduce variation in immune responses between individuals, offering a new way, alongside their ongoing work in mice, to investigate why infections affect people differently and to test potential treatments more effectively.
