Developing models to replace animals in research, a longstanding goal of animal welfare advocates, has become a priority for the National Institutes of Health, the Food and Drug Administration, and the Environmental Protection Agency. The following research methods are some of the scientifically validated alternatives used today. While they are helping to reduce the number of animals needed for research, they each have limitations. They represent a start in reaching the ultimate goal of significantly reducing and one day possibly eliminating the need for invasive research on animals without compromising our ability to work toward breakthroughs that may ease suffering in humans as well as animals.
| Method | What is it? | What is it used for? | Limitations |
|---|---|---|---|
| In vitro testing | Cells or tissue samples taken from animals or humans and prepared for laboratory study | Drug research, testing new chemicals and products on human skin, toxicology testing | In vitro techniques focus on the cellular level and therefore cannot replace whole-body testing; determining drug safety and efficacy requires testing in animals. |
| Microfluidic chip testing | Microfluidic chips contain tissue samples from different parts of the body that are linked by microchannels through which a blood substitute flows, mimicking pathways and processes in the body. This testing method provides more complex information than in vitro tests. | Studying biological and disease processes, drug metabolism | Provides less information than whole-body testing; determining drug safety and efficacy requires testing in animals. |
| Microdosing | This method enables human volunteers to be safely substituted for animals in some drug tests. It involves giving humans doses of a drug high enough to cause cellular effects, but too low to affect the entire body. | Drug testing | Considered only Phase 0 of a clinical drug trial, the earliest phase; animal testing with the full dose of a drug is needed to determine its safety and efficacy and for drug approval. |
| Imaging studies | A wide range of technologies for seeing inside the body, including magnetic resonance imaging (MRI), functional MRI (fMRI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) | Observing the effects of drugs in the body, studying brain structure and function, studying brain diseases and other neurological disorders | Cannot reveal all drug effects in the body; relies on data from animal testing. |
| Computer models and simulations | Virtual human organs, metabolism programs, and other computer- and math-based approaches to studying the human body structure, functions, and reactions | Automobile crash tests, heart studies, modeling the effects of new medicines | Findings from computer models and simulations usually need to be confirmed in whole animals. |
Sources:
AltTox.org http://alttox.org/ttrc/validation-ra/validated-ra-methods.html; T. Arora et al, “Substitute of Animals in Drug Research: An Approach Toward Fulfillment of 4Rs,” Indian Journal of Pharmaceutical Science, Jan- Feb. 2011 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3224398/; National Centre for the Replacement, Refinement, and Reduction of Animals in Research http://www.nc3rs.org.uk/page.asp?id=7 ; “Microdosing and the 3R’s,” National Centre for the Replacement, Refinement, and Reduction of Animals in Research http://www.nc3rs.org.uk/downloaddoc.asp?id=339&page=193&skin=0; Max Planck Institute for Biological Cybernetics http://hirnforschung.kyb.mpg.de/en/methods/alternative-methods.html