We ve said it before and we ll say it again: Mice are not little men

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Biomedical researchers have long used mice in the lab to learn about human diseases and to test treatments. Now, a new study strongly suggests that mice are poor models for studying trauma or infections in humans.

In a test comparing the genetic responses of mouse and human immune cells, mice had vastly different reactions to toxins and trauma, according to findings published Monday in the Proceedings of the National Academy of Sciences.

The new study, which took 10 years and involved 39 researchers from across the country, began by studying white blood cells from hundreds of patients with severe burns, trauma or sepsis to see what genes were being used by white blood cells when responding to these dangerous conditions. They found, for example, that while the mice used certain sets of genes in their responses, humans did not.

When I read the paper, I was stunned by just how bad the mouse data are, Dr Mitchell Fink, a sepsis expert at the UCLA said. It s really amazing no correlation at all. These data are so persuasive and so robust that I think funding agencies are going to take note. Until now, he said, to get funding, you had to propose experiments using the mouse model.

Since mice have been used as animal models for septic shock for many years, it is rather disturbing to learn that the model has no value, although at least we now know this. But it should be noted these findings apply only to sepsis, so it is wrong to dismiss all animal models as predictors of human disease outcome. For example, mouse models are often useful for evaluating the utility of new antibiotics in humans. says ACSH s Dr. Josh Bloom. Furthermore. he adds, it s not like there are such great alternatives. You can do all the cell-based experiments in the world, but unless a potential drug works in an animal model you have to be rather brave to put it in the clinic.

We have been saying that mice are not little men since ACSH s founding in 1978, adds ACSH s Dr. Gilbert Ross. We see the same thing happening with animal testing of all sorts of alleged toxic chemicals, which lay low rodents in various tests, but are quite safe for humans in typical exposures. Hopefully, this revelation, albeit restricted in this study to mice and a few medical conditions, will be useful to illustrate the lack of analogy between rodent and human toxicology and physiology.