Mice bred with symptoms like those of cystic fibrosis


BOSTON -- In a breakthrough that could speed the search for lifesaving treatments for cystic fibrosis, scientists report that they have developed mice with symptoms that closely mimic the most common fatal genetic disease among Americans.

Researchers at the University of North Carolina in Chapel Hill reported their success in today's issue of the journal Science. They beat out groups around the world that have also been working to develop an animal model since the disease gene was identified in 1989.

"This is a major, major discovery," said Robert J. Beall, executive vice president for medical affairs for the Cystic Fibrosis Foundation, which funded the research. "I think this is going to be a very important tool that is going to be available to scientists. It will help put the final pieces together so that we can get a cure for CF," Mr. Beall said.

The disease affects about 30,000 people in the United States, many of whom die by early adulthood, usually of pulmonary infections that result from thick mucus in the lungs.

But while the mice have many of the symptoms of cystic fibrosis, including failure to thrive and gastrointestinal blockages, they have not yet shown the major respiratory complications so typical in humans with the disease.

That may either be because they have not had time to develop the complications or because they have not yet been exposed to microbes that could lead to infections, said Dr. Richard C. Boucher of Chapel Hill, an author of the study. "When the animals live for a relatively short period of time in sterile environments, they get very modest lung disease," he said. "I think the important thing is that they did get a little."

Lung disease does not appear right away in babies born with cystic fibrosis, he said; usually it takes six months to a year to develop.

Other researchers welcomed the news of the first animal model, which the North Carolina researchers created by inserting a defective CF gene into mice and breeding them to mimic symptoms of the disease.

But some experts say it may be too soon to tell whether this model will be the perfect parallel of the disease in humans, particularly with the absence of respiratory complications.

Currently, the main treatment for cystic fibrosis is antibiotics, to fight pulmonary infections. Some drugs designed to attack the mucus are under study in small human trials. And gene therapy to replace the protein missing in cystic fibrosis has worked in a test tube.

The mouse model promises to quicken the pace of research into potential treatments, whether they be drugs or gene therapy, said Dr. Boucher and Mr. Beall of the CF Foundation.

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