Don’t fall into ‘mouse trap’ of research, warns immunologist

January 1st, 2009 - 12:19 pm ICT by IANS  

Washington, Jan 1 (IANS) An immunologist has warned against falling into the ‘mouse trap’ of research, if scientists really want to understand how humans fall sick.Mark Davis, professor of microbiology from Stanford University School of Medicine, exhorted immunologists to wean themselves from rodents and to embark on a bold, industrial-scale assault on the causes and treatment of specifically human disease.

“We seem to be in a state of denial, where there is so much invested in the mouse model that it seems almost unthinkable to look elsewhere,” said Davis.

Because experimental mice can be used to get quick answers, Davis argued, researchers look to the mouse to tell them everything. “In humans it often takes years to find out anything. There are a lot more regulatory, financial and ethical hurdles,” he said.

But when it comes to adapting therapeutic interventions that seem to cure all kinds of infectious disease, cancers and autoimmune conditions in mice for use in human beings, the record is not so good.

The vast majority of clinical trials designed to test these interventions in people end in failure. “Mice are lousy models for clinical studies,” Davis wrote in his study.

There are probably some good reasons for this, said Davis. For starters, mice are rodents, separated from humans by some 65 million years of evolutionary divergence from our common ancestor, said a Stanford release.

That’s not all. While it takes about 20 years for a person to reach sexual maturity, a mouse gets there in three months. The roughly 100 years during which the furry, diminutive animals have been domesticated and bred in labs are, therefore, the mouse equivalent of 8,000 human years, during which they have been inbred and kept relatively disease-free. They would never survive in the wild, said Davis.

Meanwhile, the past 8,000 years have seen humans crowded into cities, he said. “We’ve been selected by urbanisation, with plagues such as the bubonic plague and smallpox that routinely killed huge numbers of people, and modern scourges like HIV and malaria that still infect and kill millions each year.

“Most humans are infected with six different herpes viruses, and who knows what else. And while we’re suffering away, getting colds and flu, the mice are living in the lap of luxury in miniature condominiums, with special filters on the cage tops to keep bad things out.”

They’re in such pristine shape, Davis notes drily, that researchers have to induce facsimiles of human disease in them. These conditions may or may not accurately mirror ours.

“We can’t depend on the mouse for all the answers, because in some cases it’s not giving us the right answers,” Davis said. “But think about what we can do with people. People come to hospitals, get vaccinations, give blood and tissue samples for routine lab tests and clinical trials. We’re not learning nearly as much as we could from these samples. As with the recent history of human genetics, we could be much bolder.”

The Human Genome Project has radically accelerated the pace of human genetics, he pointed out.

The study was published in Immunity.

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