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Graphic shows steps in genetic modification of animals and timeline of xenotransplantation.
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HEALTH

Man receives heart from genetically altered pig

By Duncan Mil

January 11, 2022 - Surgeons in the U.S. have transplanted the heart of a genetically modified pig into a human, marking a step in the decades-long quest in using animal organs for life-saving transplants.

A Maryland man has become the first to receive a successful pig-to-human heart transplant. David Bennett, 57, is “still doing well” three days after the first-of-its-kind surgery and will continue to be monitored to determine whether the transplant, conducted at the University of Maryland, provides life-saving benefits, the university said in a statement.

The surgery took nine hours and saw doctors replace Bennett’s heart with one from a pig that had its genes edited specifically to provide organs to humans.

The pig, provided by Blacksburg, Virginia, company Revivicor, which raises pigs for transplant, was genetically modified in 10 different spots before birth.

One of the key reasons the human immune system rejects pig organs lies in genes responsible for producing an enzyme called alpha-1,3-galactosyltransferase (alpha-gal).

Since normal pig tissue contains active alpha-gal enzymes, antibodies in the human immune system interpret the transplanted tissue as a threat and cause an aggressive human rejection response.

Porcine DNA is genetically modified to eliminate the alpha-gal molecule from the embryos of cloned pigs. Six human genes are added to the pig DNA to prevent blood from coagulating in the heart, improve molecular compatibility and reduce the risk of rejection. Finally, scientists knock out two other genes -- one to stop the animal from growing too large and another to prevent the pig’s heart from continuing to grow after implantation.

The one-year-old pig that gave its heart to Bennett weighed about 109 kilograms; a standard male pig of the same age might weigh more than 200kg, said David Ayares, Revivicor’s executive vice president and chief scientific officer.

Sources
PUBLISHED: 11/01/2022; STORY: Graphic News
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