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US scientists genetically engineer pigs to cut human heart disease

http://www.100md.com   2006-3-27 xinhuanet
     BEIJING, March 27 (Xinhuanet) -- U.S. scientists said Sunday they had genetically engineered pigs rich in omega-3 fatty acids, compounds that have been shown to improve cardiac function and reduce the risk of heart disease in people.

    Omega-3 fatty acids have been linked to a lowered incidence of heart disease. The only way now for humans to get omega-3s is through taking dietary supplement pills or by eating certain fish. And Omega-3's are in greatest abundance in oily fish like tuna, which contains high levels of toxic mercury.

    Researchers transferred a worm gene called fat-1 into pig cells in a laboratory. They used cloning technology to create embryonic cells that were implanted into the womb of a normal pig.

    The gene produced an enzyme that converted the less desirable omega-6 fatty acids that the pigs naturally produced into omega-3s, the researchers wrote in the journal Nature Biotechnology.

    Tissue from the piglets that were born at the University of Missouri-Columbia had high levels of omega-3s and less omega-6, the researchers said. The total amount of fat was the same as in normal pigs.

    The omega-3 pigs "could represent an alternative source as well as be an ideal model for studying cardiovascular disease and autoimmune disorders" that also may be impacted by boosting the healthy fat, said Dr. Yifan Dai, a University of Pittsburgh scientist who transferred the worm gene into the pig cells.

    Harvard University's Jing Kang, one of the scientists involved in the experiment, is confident the levels of omega-3 fatty acids in the new pigs aren't high enough to ruin the flavor.

    "There should be no difference," he said, adding as far as he can tell the pigs "don't smell fishy."

    Getting the pigs to market could also be a challenge. The Food and Drug Administration has not allowed any genetically altered animals to enter the food chain, despite scientific studies showing the animals are safe.

    Before clearing the meat for consumption, the FDA requires detailed biological information, including controlled studies comparing modified animals to normal ones.

    "They treat them like they are a new drug," said University of Illinois professor Matthew Wheeler, who has been working on genetically engineered animals for 13 years.

    Also, the lead author of the new paper said pigs were only the beginning, adding that he was also developing cows that make omega-3's in their milk and chickens that have the fatty acids in their eggs. Enditem


    Editor: Lu Hui