Researchers in New York have transplanted pig hearts into two brain-dead people over the past month, the latest in a series of developments in the long quest to one day save human lives with animal organs.
The experiments announced Tuesday come after a historic but failed attempt earlier this year to use a pig’s heart to save a dying Maryland man, a rehearsal of sorts before scientists try again on life. .
Between the lessons: Practice with the deceased is important.
“We learned so much from the first one that the second one is so much better,” said Dr. Nader Moazami, who led operations at NYU Langone Health. “You stand there in awe” when a pig’s heart begins to beat in a human body.
This time, Moazami’s team mimicked how heart transplants are routinely performed. Once last month and once last week, the researchers traveled to a facility that housed genetically modified pigs, removed the necessary hearts, put them on ice and flew them hundreds of miles back to New York.
They used special new methods to detect any animal viruses of concern before sewing the heart into the chest of each deceased recipient: a Pennsylvania Vietnam veteran with a long history of heart disease and a New York woman who had previously benefited from a transplant. in life
Then came three days of more intense testing than living patients could tolerate, including frequent organ biopsies, before doctors switched off life support.
The Food and Drug Administration is already considering whether to allow a small number of Americans in need of a new organ to volunteer for rigorous studies of pig hearts or kidneys. NYU Langone is among three transplant centers planning trials, and is scheduled to meet with the FDA in August to discuss requirements.
Tests in the deceased could help refine how early trials in the living are designed, said Dr. David Klassen of the United Network for Organ Sharing, which oversees the country’s transplant system.
“They serve as a kind of important stepping stone,” said Klassen, who wonders if researchers might consider following organs for a week or so in a donated body instead of just three days.
One of the deceased beneficiaries, Lawrence Kelly, had suffered from heart disease for most of his life and “would be very happy to know how much his contribution to this research will help people like him” in the future, his long-time partner said. AliceMichael. reporters on Tuesday.
Animal-to-human transplants, what scientists call xenotransplantation, have been tried for decades without success, as people’s immune systems almost instantly attacked the foreign tissue. Now, pigs are being genetically modified to make their organs more human-like, raising hopes that they could one day help fill the shortage of donated organs. More than 100,000 people are on the national transplant waiting list, most of them kidney patients, and thousands die each year before their turn comes.
The most ambitious attempt yet came in January, when doctors at the University of Maryland Medical Center transplanted a pig’s heart into a dying 57-year-old. David Bennett survived for two months, evidence that xenotransplantation was at least possible. But initial tests did not detect that the organ harbored an animal virus. It is not yet known what caused Bennett’s new heart to fail and whether that virus played a role, the Maryland researchers recently reported in the New England Journal of Medicine.
Months earlier, the New York University team and researchers at the University of Alabama at Birmingham were separately testing pig kidney transplants in the deceased, people who had donated their bodies to science.
Recent NYU cardiac experiments will add to the evidence as the FDA decides whether to allow formal studies in living patients.
But Dr. Robert Montgomery of NYU Langone, a kidney transplant surgeon who received his own heart transplant, said continuing careful experiments on the deceased is critical to discovering the best methods “in an environment where the life of a person is not at stake”.
“This is not a unique situation. It will take years of learning what is important and what is not important to make this work,” said Montgomery, who has a list of nearly 50 people who have called in desperation to volunteer for a pig kidney transplant.
The FDA has not said how soon it might decide whether to allow such studies. At a recent two-day public meeting, the agency’s science advisers said it was time to give it a try despite the long list of questions. They include the best way to modify pigs, as several biotech companies, including Revivicor, which supplied New York University’s organs, are looking at different options.
It’s not even clear which organ to test first in a clinical trial. If a pig kidney fails, the patient can always survive on dialysis. However, some of the FDA advisers said starting with the heart might be better. Experiments with pig kidneys in deceased humans showed that the organs produced urine. But it remains unknown whether pig kidneys do another important job, processing drugs, in the same way that human kidneys do.
