The number of rodents used in biomedical research is unclear, but estimates have ranged from 10 million to over 100 million every year in the United States alone. That is a lot of animals. Scientists are now working on developing a new kind of non-mammalian model that might reduce the number of rodents used in research, which would not only be great for the animals, it could also accelerate research and lower costs dramatically. In a new study reported in Nature Communications, researchers have shown that caterpillars could be used to study human gut inflammation instead of rodent models.
The larvae of the tobacco hornworm (Manduca sexta) was selected as a potential new gut disease model because the structure and physiology of their guts are highly similar to what is found in humans; there is a high degree of conservation between this aspect of the species, noted study co-author Jan Grimm, MD, Ph.D., a radiologist and nuclear medicine physician at Memorial Sloan Kettering Cancer Center's Sloan Kettering Institute.
These animals are basically one, long bowel. Tobacco hornworm caterpillars can also be imaged with the same tools, like MRIs, PET, or CT scans that we use to image humans, added Grimm. Nematode worms or C. elegans, another common research model, are too small to be used in these instruments.
About 75 percent of human genes that have been linked to disease have counterparts in insects, so caterpillars and other models may be very useful in preclinical research.
Caterpillars are also invertebrates, so their use is not regulated in the same way that rodent use is. New experiments that involve mice can often require obtaining approval from a committee after making a justification for those experiments. But researchers can simply design an experiment and test it on caterpillars without having to obtain institutional approval. These animals also grow slowly, and can be easily raised in plexiglass containers with wet paper towels and fresh leaves; they don't require special facilities, housing, care, and feeding routines.
While it may seem like an outlandish idea to some, this may be a great way to accelerate biomedical research at a very low cost, and spare the lives of many rodents in the process.
Sources: Memorial Sloan Kettering Cancer Center, Nature Communications
