Can Studies on Mice Really Apply to Humans?

This little guy may be more similar to you than you think. Photo via Shutterstock

How many times have you been floored by an eye-catching headline about medical research, only to become far less impressed when you see the study was only done in mice? Using mice is the norm in medical research, but the differences between mice and humans account for many of the promising-looking discoveries that end up failing when they’re translated to human trials. In an effort to prevent some of those disappointing failures, Harvard set out to determine exactly how similar mice and human immune systems are.

Tal Shay, a postdoctoral researcher at the Broad Institute, led a team of scientists from Harvard Medical School, the Broad, and Stanford University in an extensive comparison of how comparable genes are expressed in mouse and human immune cells at different times and in various situations (when fighting an infection, for example). Amazingly, the researchers found that the two systems were approximately 80 percent the same—but there were some key differences that could lead mouse-based studies not to translate to humans. Shay and her colleagues published their findings in the journal PNAS and created a user-friendly web database that other researchers can use as they embark on studies.

A report from Harvard quotes Shay about the study:

“What we assume most people will be interested in knowing is, if they are working on gene X, whether gene X has the same expression pattern in human and mouse immune systems,” Shay said. “Most lineages have the same expression signature but some genes behave differently and we think it’s important for why some things work in mice but not humans and the other way around.”

The research is important because, despite their occasional flaws, mouse models are still some of the most useful tools available to biomedical researchers, and knowing when mouse trials will not transfer over could save scientists valuable time and funding. And judging by how many studies are done in mice first—everything from surgery recovery time to Botox health risks to autoimmune disease development—this data will go to good use. The Harvard report quotes PNAS paper co-author Christophe Benoist:

“Because the differentiation and function of human and mouse lineages are highly related, there is the expectation of conservation, so it is important to know when inter-species inferences may be an issue. Mouse models are far too valuable to be jettisoned for pre-clinical exploration, but it is important to know when caution is needed.”