US surgeons successfully implanted a heart from a genetically modified pig in a 57-year-old man, a medical first that could one day help address the chronic shortage of organ donation.
The “historic” trial took place on Friday, the University of Maryland Medical School said in a statement on Monday. Although the patient’s prognosis is far from certain, it represents an important milestone in animal-to-human transplantation.
The patient, David Bennett, was an out of the question for a human transplant – a decision that is often made when the recipient is in very poor health.
He is now recovering and will be carefully monitored to see how the new organ is working.
“It was either dying or doing this transplant. I want to live. I know it’s a shot in the dark, but it’s my last choice,” said the Maryland resident the day before the operation.
Bennett, who has been bedridden on a cardiopulmonary bypass machine for the past few months, added, “I look forward to getting up after my recovery.”
The Food and Drug Administration issued an emergency permit for the operation on New Year’s Eve as a last resort for a patient unsuitable for a conventional transplant.
“This was a breakthrough operation and brings us one step closer to resolving the organ scarcity crisis,” said Bartley Griffith, who surgically transplanted the pig heart.
“We are proceeding cautiously, but we are also optimistic that this world’s first operation will offer patients an important new option in the future.”
Muhammad Mohiuddin, co-founder of the university’s cardiac xenotransplantation program, added that the operation marks the culmination of years of research with transplants from pigs to baboons with survival times in excess of nine months.
“The successful procedure provided valuable information to help the medical community improve this potentially life-saving technique in future patients,” he said.
10 unique gene edits
Bennett’s donor pig was part of a herd that had been genetically modified.
Three genes that would have led to human rejection of pig organs have been “knocked out,” as has one gene that would have led to overgrowth of pig heart tissue.
Six human genes responsible for human acceptance have been added to the genome, for a total of 10 unique gene edits.
The edit was done by Virginia biotech company Revivicor, which also supplied the pig used in a groundbreaking kidney transplant on a brain-dead patient in New York in October.
But while this surgery was purely a proof-of-concept experiment, and the kidney was connected outside the patient’s body, the new surgery is designed to save someone’s life.
The donated organ was kept in an organ preservation device prior to surgery, and the team also used an experimental new drug from Kiniksa Pharmaceuticals along with traditional anti-rejection drugs to suppress the immune system.
About 110,000 Americans are currently waiting for an organ transplant, and according to official figures, more than 6,000 patients die before getting one each year.
In order to meet the demand, doctors have long been interested in so-called xenotransplantation or cross-species organ donation, the experiments of which date back to the 17th century.
Early research focused on organ harvesting from primates – for example, a newborn baby known as the “baby fae” had a baboon heart transplanted in 1984, but it only survived 20 days.
Nowadays, pig heart valves are used extensively in humans, and pig skin is transplanted to human burn victims.
Pigs are ideal donors because of their size, rapid growth and large litters, as well as the fact that they are already raised as a food source.
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