Scientists at Cambridge have announced a major push to transform how drugs are tested, replacing traditional animal experiments with miniature human organs grown in the lab. The effort, backed by £20 million from the Medical Research Council, will establish a national hub dedicated to developing standardised "organoids"—tiny tissue clusters grown from real NHS patients' cells that mirror the key features of full-scale human organs.
At the heart of the programme is a simple but powerful insight: animals often fail as stand-ins for humans. Historically, more than 90% of drugs that clear animal testing go on to fail in human clinical trials, raising serious questions about the predictive value of current methods. Organoids grown from human tissue aim to close that gap.
"A lot of human diseases either do not occur in animals or occur in a different way because they're not human," said Matthias Zilbauer, a clinical professor of paediatric gastroenterology at the Cambridge Stem Cell Institute. "We want tests and models that can tell us which treatments work, and in what patients, and a mouse cannot tell us that."
Researchers have been cultivating organoids for over a decade, and evidence shows that clumps of human tissue smaller than a millimetre can accurately replicate how organs respond to disease and drugs. What the new Cambridge hub adds is scale, standardisation, and access: it will create a validated library of organoids—covering conditions from inflammatory bowel disease and cancer to neurological disorders—and make them available to both academic researchers and the pharmaceutical industry worldwide.
Personalised Medicine at Scale
One of the most exciting possibilities is truly personalised medicine. By testing drug candidates on organoids derived from individual patients' cells, scientists can determine not just whether a drug works in general, but which specific patients are likely to respond—and why. This approach could spare future patients from treatments that won't help them, while accelerating development of those that will.
Zilbauer's team is beginning with organoids for ulcerative colitis and Crohn's disease, conditions that affect hundreds of millions globally and for which many patients still lack effective therapies. Other researchers at the hub will focus on tumour organoids to improve cancer treatments and brain organoids to understand conditions like dementia and Parkinson's disease.
Reducing Animal Use
The hub forms part of a broader UK government strategy to fast-track the reduction of animal experiments. In 2025, there were 2.54 million animal testing procedures in Britain—down 3.8% on the previous year—but scientists see organoids as the pathway to a far more dramatic reduction.
Alongside the Cambridge hub, Innovate UK has funded nine additional projects aimed specifically at eliminating animals from drug safety testing. One company, VivoSphere, is growing heart cells in tiny gel spheres to replace safety tests that currently involve up to 100 animals. By catching toxicity earlier, such systems could simultaneously improve safety and speed the development of new medicines.
"One of the huge advantages of organoids, organs-on-a-chip and other in vitro microphysiological systems is that, unlike animal models, they have real potential to deliver the promise of truly personalised medicine for individual patients," said Dr Juliet Dukes of the charity Replacing Animal Research. "It is all very exciting."
The Cambridge hub is expected to become a global centre for organoid science, with its findings shared openly so researchers worldwide can move beyond animal models—not just for ethical reasons, but because human organoids simply yield better data.
It marks a genuine turning point: the beginning of a new era in which the biology of the patient, not the biology of the mouse, guides the search for the next generation of medicines.
