Tiny Lab-Grown Organs Could Change How We Test New Medicines

The University of Cambridge has launched a £20 million project to grow tiny human organs in the lab, using cells from NHS patients. The goal is to test drugs on these miniature organs instead of animals, making the process more accurate and reducing the number of animals used in research. The project, funded by the Medical Research Council, was reported by The Guardian on 12 August 2026. It will create a research hub that grows these mini-organs and shares them with scientists and drug companies.

These mini-organs are called organoids. They are clusters of human cells grown in the lab that take on the shape and basic function of real organs. They are smaller than a millimetre. Imagine a simplified, scaled-down version of a heart or a liver that can show how real tissue reacts to a disease or a medicine. Scientists have been growing organoids for over a decade, but the Cambridge hub aims to produce them on a larger, more reliable scale.

The reason this matters is a surprising number: more than 90% of drugs that pass animal testing go on to fail in human trials. In the UK alone, 2.54 million animal testing procedures were carried out in the year before the Guardian report. The main purpose of animal testing is to check whether a drug is toxic — meaning harmful — and whether it works safely in the body, as a 2024 review published in PMC explained. Because organoids are made from human cells, they give scientists a more direct view of how a drug might affect a person, as The Conversation noted in March 2026.

The Cambridge project is part of a wider UK government plan, created under Prime Minister Keir Starmer, to reduce the use of animals in research. The plan relies on methods called "new approach methodologies," which include organoids, organ-on-a-chip systems (tiny devices that mimic how organs work), and artificial intelligence. Other countries are moving in the same direction. In the United States, a law called the FDA Modernization Act 2.0 already allows non-animal methods for drug testing, and Reuters reported in March 2026 that the FDA is encouraging the use of 3D models like organoids to make early drug studies cheaper and faster.

Matthias Zilbauer, a professor at the Cambridge Stem Cell Institute, is a lead figure in the project. His team has been growing "mini-guts" — tiny versions of the intestine — to test new treatments and see how they affect the gut lining, work described by the Cambridge Stem Cell Institute in 2024. The new hub will apply this approach to other organs too.

Cambridge already has several organoid projects feeding into the hub. The Cambridge Biomedical Centre is growing organoids from liver tumours to test them as drug-testing models. The Brenton Group at the Cancer Research UK Cambridge Institute is developing organoid methods that help cells survive better than older lab techniques. The HIT-CF program is testing drugs on rectal organoids from cystic fibrosis patients with rare genetic mutations. A UKRI-funded project is growing human lung organoids for drug toxicity testing and gene screening. Another is studying lung cancer using organoids grown from patient tissue.

The hub's plan to create a standardised library of organoids is where things get practical. If scientists grow organoids from many different patients, drug companies could test their medicines against tissue that reflects real genetic variety — before moving to human trials. Researchers can expose organoids to a new drug and watch what happens: inflammation, cell death, or other biological reactions, all in human tissue rather than in animals. Brain organoids are also being developed for drug screening, with both advantages and challenges noted in a 2024 review in PMC.

Researchers at the Harvard Stem Cell Institute showed as early as 2019 that growing kidney organoids with fluid flowing through them helped them develop blood vessels and mature, making them more useful for drug testing. A 2022 review in Nature Reviews Genetics by Donald Ingber described how organ-on-chip systems have been used to model diseases, rare genetic conditions, and drug responses. The Cambridge hub's library would bring together what has so far been scattered work across different labs.

The broader context here is a shift that has been building slowly but is now becoming visible. The rules and systems that govern drug testing were designed around animal studies, but the technologies that could replace much of that testing are catching up. The 90% failure rate of animal-tested drugs in human trials has been known for years, but it carries more weight now that organoids, organ-on-chip systems, and AI have moved from early experiments to tools that can be standardised and scaled. The UK government's decision to place the Cambridge hub inside a formal strategy — and the FDA's similar push in the US — suggests that leaders see reducing animal testing not just as a kindness to animals but as a way to stay competitive in the global pharmaceutical industry. The countries that build reliable human-cell-based testing systems first may develop drugs faster and attract more research investment.

Whether organoids can fully replace animal testing in every situation is still uncertain. Some complex effects — like how the immune system reacts, how a drug moves through multiple organs, or long-term toxicity — are not yet reliably captured by organoids, even when several are used together. The Cambridge hub's focus on standardisation and validation is an acknowledgment that the challenge is no longer just growing organoids. It is proving they work well enough that regulators and drug companies will trust them at scale.