In a milestone for medicine, American surgeons transplanted a pig’s heart into a human patient in a last-ditch effort to save his life, and the Maryland hospital where the procedure was performed said the recipient is in good condition three days later. of experimental surgery.
While it is too early to tell if the operation will actually work, it does represent a milestone in a multi-decade quest to one day transplant organs of animal origin to save human lives. Doctors from the University of Maryland Medical Center noted that the transplant demonstrated that the heart of a genetically modified animal can function in the human body without immediate rejection.
The patient, David Bennett, 57, knew there was no guarantee that the experiment would work, but he was dying, was ineligible for a human heart, and had no other options, his son said. “It was either die or undergo this transplant. I want to live. I know the chances are low, but it is my last option,” Bennett said a day before the surgery, according to the statement released by the University of Maryland School of Medicine. .
Yesterday, Bennett was breathing on his own, although he was still on a cardiopulmonary bypass pump to support his new heart. The next few weeks will be crucial: In them, the patient will recover from the surgery and the doctors will carefully monitor the performance of his heart.
There is a huge shortage of donated human organs for transplantation, prompting scientists to try to figure out how to use animal organs instead. Just over 3,800 heart transplants were performed in the United States last year, a record number, according to the United Network for Organ Sharing (UNOS), the body that oversees the national transplant system. “If this works, there will be an inexhaustible supply of these organs for suffering patients,” said Dr. Muhammad Mohiuddin, scientific director of the university’s xenotransplantation program.
However, previous attempts to perform these types of transplants – known as xenotransplants – have failed, largely because the body of patients quickly rejects animal organs. One of the best known cases was recorded in 1984, when baby Fae, a dying girl, survived 21 days with the heart of a baboon.
The difference this time around is that Maryland surgeons used the genome-edited heart of a pig to remove a sugar from its cells that is responsible for almost immediate organ rejection. Several biotech companies are developing pig organs for transplantation into humans. The one that was used in Friday’s surgery was provided by Revivicor, a subsidiary of United Therapeutics. “I suppose it can be defined as a watershed,” said Dr. David Klassen, UNOS director of medicine, referring to transplantation in Maryland.
Either way, Klassen cautioned that it’s only the first tentative step in finding out if xenotransplantation might finally work.
The Food and Drug Administration (FDA), which oversees xenotransplantation experiments, gave the green light to the surgery with an emergency authorization for “compassionate use”, which applies when the patient has no more options.
Sharing the data gathered from this transplant will be crucial before offering this option to other patients, said Karen Maschke, a senior researcher at the Hastings Center, which is helping develop the ethical and policy recommendations for the first funded clinical trials. by the National Institutes of Health. “It would not be advisable to rush animal-to-human transplants without this information,” Maschke stressed.
Over the years, scientists have moved from primates to pigs, altering their genes. Just last September, New York researchers conducted an experiment that suggested that these types of pigs could facilitate transplants from animals to humans. Doctors temporarily connected a pig kidney to a human corpse and saw that it began to function.
The transplant performed in Maryland took the experiment to the next level, said Dr. Robert Montgomery, who spearheaded the previous experiment at NYU Langone Health. “This is a truly remarkable advance,” Montgomery said in a statement. “As a heart transplant recipient and suffering from a genetic heart condition, I am extremely excited about this news and the hope it brings to my family. and the other patients for whom this advancement will eventually save their lives. ”
Last Friday’s surgery at a Baltimore hospital took seven hours. Dr. Bartley Griffith, who performed the operation, said the patient’s health problem _ heart failure and arrhythmia _ made him ineligible for a human heart or ventricular assist device.
Before offering Bennett the option, Griffith had transplanted pig hearts into about 50 baboons in a span of five years. “Every day we are learning a lot from this gentleman, ” Griffith said.“ And so far, we are happy with our decision to proceed. And so is he: Today he had a huge smile. ”
Pig heart valves have also been used successfully in humans for decades, and Bennett’s son noted that his father had already received one about 10 years ago. “He is aware of the magnitude and importance of what happened,” David Bennett Jr. said of his father. “It could not survive, or it could live a day, or a couple of days. I mean, right now we are in uncharted territory.”