Trends In The Use Of Animal Testing Alternatives

Today’s technological innovations could mean saying goodbye to the use of animals as test subjects in medical research. Non-animal methods (NAMs), from cell culturing to computer modeling, are animal-free alternatives — and they’ve been gaining steam in recent years. Developers, funders, and policymakers want to know which research areas use NAMs most and whether a higher use of NAMs corresponds with a lower use of animals. Three researchers scanned existing research to answer these questions and more.

Using strategic search criteria, they compiled research papers from 2003 to 2022, spanning seven research areas and five countries. They looked specifically at breast cancer, lung disease, blood cancer, heart disease, neurodegenerative diseases, diabetes, and toxicology because of scientific interest and prevalence in research. They chose the U.S. and China for their major role in global science research and development, while France, Germany, and the U.K. were selected because they have both the largest economies and highest use of animals in research and testing in Europe.

The researchers counted how many papers belonged to each of three categories (NAMs-only, animal-only, and both), excluding those with human participants. They also wanted to look at the popularity of more advanced NAMs, so they counted papers specifically using tissue, lab-on-a-chip, stem cell, and/or computer-based (in silico) technologies. To compare across research areas and countries, the researchers calculated proportions that accounted for differences in publication rates. If a paper involved more than one of the countries or advanced methods being studied, the researchers counted it for each relevant category.

Here’s what they found:

• NAMs-only research has been more common than animal-based research (the authors define this as research involving animals only or both NAMs and animals) for the past 20 years. NAMs-only research has also been increasing at a much faster rate, with the gap between it and animal-based research growing. By 2022, there were nearly three times as many NAMs-only papers as animal-based ones. Of the studies the authors looked at from that year, about 73% were NAMS-only, 24% used both NAMs and animals, and just 3% used animals only. Thus, reliance on animals for major biomedical and toxicology research appears to be decreasing.
• While the number of animal-only papers has stayed about the same, and papers using both NAMs and animals have increased slightly, NAMs-only publications have surged. Because the number of papers published has grown overall, animal-based research represents an increasingly smaller share of the work.
• Use of NAMs-only versus animal-based research varies by research area. Breast cancer and lung disease have consistently had a higher use of NAMS-only compared to animal-based research. Meanwhile, heart disease, diabetes, and toxicology have demonstrated the greatest shift away from animal-based research towards NAMs-only. Neurodegenerative disease research showed a greater reliance on animal-based methods.
• Adoption of NAMs also varies by country. Of the countries studied, the U.K. leads for the highest overall usage of NAMs-only compared to animals, with over four NAMs-only papers for every one animal-based paper in 2022. China has seen the slowest uptake of NAMs-only usage, although there’s still been a shift away from animal-based research.
• In 2022, 35 to 55% of NAMs-only research in the seven research areas used advanced methods. Of those, non-animal tissue and in silico methods have been much more popular than lab-on-a-chip and stem cell methods.
• Laws protecting animals in scientific research could help drive the adoption of NAMs. The authors observed notable upticks of NAMs in research in the early 2000s and then again around 2016 to 2018. They suggest that changes to laws and regulations, particularly in Europe, could have played a role.

The authors acknowledge the way they searched for and sorted the papers could have led to some being misclassified or left out. However, their method more likely understated NAMs usage, meaning the shift towards NAMs may be even greater than these findings suggest. It’s possible that some of the NAMs-only studies confirmed — or could confirm — their results using animals in a follow-up, but the authors didn’t see evidence of this. Importantly, each NAMS-only paper identified here represents work that its authors saw as scientifically valuable enough to publish on its own.

NAMs lead biomedical and toxicology research in key areas of study and countries, and their use continues to grow rapidly. Still, this analysis shows that research methods, including the use of animal testing and advanced NAMs, varies widely across fields. Some researchers continue to feel their research requires live animals.

Animal advocates can help support stricter welfare regulations around using animals in scientific research, as these appear to drive NAMs usage. Beyond that, they should look into reasons why some researchers or research areas face challenges embracing NAMs fully. Together, context-aware advocacy can work hand-in-hand with technological advancements to make animal testing a thing of the past.