The National Institutes of Health recently announced a landmark initiative to expand human-based science while reducing animal use. The world’s largest funder of biomedical and public health research will now prioritize innovative health research, leaving outdated animal experiments behind.
The announcement highlights the scientific limitations of translating findings from animals to humans. Paired with growing crises of illnesses such as Alzheimer’s disease, cancer and heart disease, these limitations stagnate medical advances. NIH investment in research to better understand and treat disease is crucial for improving the health of Americans. As Director Jay Bhattacharya points out, by expanding human-based research, this initiative will usher in a new era of innovation, improve health care outcomes and deliver life-changing treatments.
Methods like tissue chips, organoids and bioprinting are already being used to replace animals and improve clinical translation, including in disease modeling, precision medicine and regulatory toxicology. These methods use human cells, tissue and data to replicate human-specific biology and disease traits and have enormous potential to revolutionize medical research and testing.
A 2022 economic analysis estimated that the use of more predictive, preclinical non-animal technologies instead of animal tests could generate over $24 billion in increased research productivity, resulting in streamlined drug development and potential cost savings for patients. Indeed, this is the rationale for the Food and Drug Administration’s new plan to phase out animal testing requirements for monoclonal antibodies and other drugs.
Historically, billions of dollars — as much as half of the NIH’s budget for research — has been spent every year on animal experiments that do not translate well to human clinical outcomes. This research results in the harming and killing of millions of animals annually, diverts funds from more effective human-based approaches, delays medical breakthroughs that patients desperately need and puts clinical-trial participants at risk of adverse effects that were not detected in poorly predictive preclinical animal tests. The NIH will now take the necessary steps to overcome these barriers.
The NIH has made steady progress toward the development and use of non-animal research approaches. In 2024, the agency accepted comprehensive recommendations on catalyzing non-animal approaches made by an advisory group. In conjunction, a new program called Complement-ARIE was launched that aimed to speed up the development, standardization, validation and use of such methods. The new announcement builds on this progress in a major way, establishing a new office to coordinate NIH-wide efforts to improve the use of non-animal approaches and committing to expand funding, training, and infrastructure for human-based science.
The initiative also addresses review-related barriers to the broader use of non-animal methods. Our team leads an international collaboration aimed at characterizing and mitigating a phenomenon called animal methods bias, in which peer reviewers of grant applications or scientific studies prefer animal-based methods or lack the expertise necessary to adequately review non-animal methods. Consequently, researchers who use non-animal methods can receive unfair review comments, sometimes resulting in the rejection of funding or publishing submissions. The new NIH initiative will implement funding evaluation criteria to help improve review quality and ensure impartiality toward different methods. It will also provide bias mitigation training to review staff and integrate non-animal expertise in review groups. These are all measures our team has been advocating for.
The initiative establishes another provision that will be crucial for public trust: public reporting of animal- and non-animal-based spending. Over the years, snapshots of the funding landscape have rarely been made available. In 2012, an NIH staff member estimated that 47 percent of NIH-funded grants had an animal research component. A 2016 blog post (removed but still available on the web archive) indicated that about 47 percent of extramural research project grants used mice and that mouse use was trending upward. A 2023 advisory committee presentation indicated an upward trend in NIH-funded research using non-animal alternatives, landing at about 8 percent in 2021. Regular, clear funding data will help the agency stay accountable to the initiative’s goals.
While an improvement over 10 or 20 years ago, NIH investment in non-animal alternatives still pales in comparison to its bankrolling of animal research. Much work remains to overcome the stronghold animal experiments have on biomedical research, upheld by centuries of tradition, the research animal trade and methods bias. Bhattacharya’s announcement indicates the NIH is ready to tackle these crucial issues.
Another recent agency announcement promotes the importance of supporting a diversity of ideas in science “in the edge cases where scientists are pursuing evidence that others find inconvenient or objectionable.” Unraveling our reliance on animal experiments will require embracing fresh perspectives and disrupting the status quo, and the NIH is now prioritizing this work. The new initiative to prioritize human-based science is necessary, and it will have profound impacts on human health.
Catharine E. Krebs, PhD, is a medical research program manager with the Physicians Committee for Responsible Medicine. Elizabeth Baker, JD, is the director of research policy with the Physicians Committee.
