Alternatives to animal experiments are shaping the future of science

By Sara Amundson and Kitty Block

For years our undercover investigations at U.S. animal research laboratories have helped to raise awareness about the immense animal suffering caused by animal testing and experimentation. Pregnant rabbits are force-fed toxic pesticides. Cats have their spinal cords damaged and are forced to run on treadmills. Rats are placed in small tubes and made to inhale cigarette smoke.

It’s estimated that more than 50 million dogs, cats, monkeys, rabbits, rats and other animals endure painful experiments like these in the U.S. each year. The horrors of animal testing appear to increasingly weigh on popular consciousness: Our short film Save Ralph about a laboratory “tester” rabbit inspired nearly 800 million #SaveRalph posts and homages on TikTok and drove more than 5 million people to sign a petition calling for an end to cosmetics animal testing; animal testing is even a major theme in the latest Guardians of the Galaxy movie.

We are determined to find ways to spare animals from suffering. Thanks to advances in technologies that test treatments for diseases and the effects of products, we don’t have to choose between saving human lives or animal lives.

Animal experiments are not a necessary evil to guarantee human or environmental health and safety; it’s increasingly clear that an unquestioning faith on animal tests may hinder—rather than help—efforts to ensure that products designed to combat human diseases and conditions are effective. This is because applying what works in another species under artificial conditions to what works in a human being in the real world has always been approximate.

A drug that may work for mice often won’t work for monkeys, and a drug that works for monkeys often won’t work for humans. About 90% of drugs ultimately fail in human trials following animal tests. And the inverse also occurs: A drug found to be toxic to dogs will likely never advance to human clinical trials, meaning that potentially lifesaving medicines are not pursued.

Luckily, we are on the verge of a paradigm shift. The advanced non-animal technologies currently in use and development are based on human biology. Human cells, tissues and organs, 3D bioprinting, robotics, computer models and other cutting-edge technologies are far more sophisticated and, compared to animal experiments, can more accurately and effectively predict how people will respond to drugs, chemicals, and treatments. Some of these modern approaches even use a patient’s own cells to test treatments, or they use drugs based on a person’s unique makeup, known as personalized medicine.

Here are just some of the conditions currently benefiting from advanced technologies shaping the future of science and human health, with no animals harmed in the process:

Cystic fibrosis: Organoids—which are 3D replicas of human organs—created with intestinal cells from people with cystic fibrosis were used to test various drugs to determine which drug would be most effective in each person.

Zika virus: Brain organoids created with human cells proved that the Zika virus was causing microcephaly (small head size) in babies born to mothers who were infected with the virus. This finding would not have been possible in animal experiments due to differences in animal and human brain structure. Scientists then used brain organoids to test potential drugs that could be used to prevent or reduce the damage caused by microcephaly.

Cancer: A lung organ-on-a-chip—a tiny 3D chip created from human cells that looks and functions like a miniature human organ—showed that the fluid buildup in the lungs caused by a drug frequently used by cancer patients was triggered by a patient’s lungs expanding and contracting, a finding that would not have been possible in animal experiments because researchers can’t stop and restart an animal’s lungs. The organ-on-a-chip was then used to test for drugs that would reduce the fluid buildup.

Chronic inflammatory demyelinating neuropathy: A nervous system organ-on-a-chip using human cells and blood samples was created to show that muscle weakness in people with CIDP—a rare autoimmune condition—was caused by a component in the blood causing nerve damage, leading to the muscle weakness. The results allowed scientists to get approval for a human clinical trial for a drug to treat the condition in people with CIDP. Rare conditions can’t be studied using animal experiments because scientists can’t recreate the diseases in animals, but scientists are developing organs-on-chips using cells from patients to understand these diseases and test possible treatments.

Skin allergies: A series of non-animal tests examining how human cells react to chemicals and how those chemicals interact with other substances is being used to determine if ingredients in everyday products such as laundry detergent, body lotion and drain cleaner will trigger an allergic reaction in human skin. These non-animal approaches have been proven to be more accurate than the outdated tests on guinea pigs and mice that are still used.

Heart arrythmias: Computer models using recordings from human heart activity are being used to test the adverse effects of potential drugs. Many drugs that are successfully tested in animals fail in human clinical trials because of dangerous effects on the human heart. This approach allows researchers to screen out drugs before they are tested in humans—without using animals.

Autism spectrum disorder: Scientists use non-embryonic stem cells from the discarded baby teeth of children with ASD to create nerve cells, which can be used to study how the brains of children with ASD are different.

Pioneering technologies like these are already revolutionizing human health. But inadequate funding, slow processes for validation and regulatory acceptance, and decisions by research funding bodies to continue supporting irrelevant animal models are limiting how quickly they are able to supplant animal experiments.

We are urging state and federal governments, regulatory agencies (such as the Food and Drug Administration, the Environmental Protection Agency and the National Institutes of Health), companies and universities to drastically increase the use of non-animal methods and investments in the development of new human-based, non-animal approaches. The millions of animals needlessly suffering in laboratories right now cannot wait.