For decades, the humble laboratory mouse has stood as a cornerstone of life sciences and biomedical research worldwide. These small rodents provide scientists with unparalleled insights into human biology, driving medical progress from the lab bench to the clinic. Their central role is no accident; it stems from a profound genetic and anatomical kinship with humans, making them an irreplaceable model for understanding disease and testing new treatments.
The Genetic Blueprint: Why Mice Mirror Humans
The extraordinary value of mice in research is rooted in biology. Approximately 95% of protein-coding genes are identical in mice and humans. This remarkable genetic overlap makes them highly relevant for studying human ailments like diabetes, cancer, and muscular dystrophy. Furthermore, their genome has been completely sequenced. This allows researchers to switch specific genes on or off to observe the effects—a process that is ethically and practically impossible in human subjects.
Their practical advantages are equally significant. Mice have a short lifespan of two to three years, enabling scientists to study the entire progression of a disease or ageing process in a compressed timeframe. They also reproduce quickly, with large litters and short gestation periods. This ensures a reliable supply for large-scale studies, which is critical when responding to rapidly evolving health threats like pandemics.
From Lab to Life-Saving Treatments
The impact of mouse models on modern medicine is vast and tangible. In infectious disease research, they have been pivotal in studying influenza, Ebola, and most recently, COVID-19. While human cells can be studied in a dish, only a living organism can replicate the complex immune response to an infection. For COVID-19, scientists used genetically engineered "humanised" mice that carried the human ACE2 receptor, which the SARS-CoV-2 virus uses to enter cells. This model was crucial for rapidly understanding transmission, immune response, and vaccine efficacy.
In the fight against cancer, mice have been nothing short of revolutionary. As documented by PubMed Central, the development of the breakthrough breast cancer drug Herceptin was made possible by foundational studies in mice. These studies revealed the role of the HER2 protein in tumor growth, and testing in mice provided the essential preclinical data to advance to human trials. Mice are also central to cutting-edge cancer immunotherapy, including the Nobel Prize-winning research on immune checkpoint inhibitors by James Allison and Tasuku Honjo in 2018.
Beyond Disease: Ethics and the Future of Research
The use of mice extends beyond cancer and infections to areas like obesity, asthma, depression, and even space physiology. They are also fundamental to basic research exploring how genes, proteins, and cells function—the bedrock of all medical knowledge.
This research is governed by strict ethical frameworks, most notably the 3Rs principle: Replace, Reduce, Refine. Scientists are encouraged to replace animal studies with alternatives like lab-grown organoids or advanced cell models whenever possible. When animals are necessary, the number used is reduced by sharing genetically altered strains and preserving embryos. The "Refine" aspect focuses on improving animal welfare through better housing, such as using sensors in home cages to monitor behaviour and reduce stress, ensuring research is both responsible and scientifically robust.
While rats are often preferred for behavioural and addiction studies due to their intelligence, mice remain the model of choice for genetics, immunology, and disease modeling. The advent of precise gene-editing tools like CRISPR has further refined the creation of "humanised" mouse models, making them even more accurate bridges between laboratory discovery and human clinical application. These tiny creatures continue to be our most powerful allies in unraveling the mysteries of biology and forging the medical breakthroughs of tomorrow.
