Maryland patient’s experimental surgery prompts some researchers to consider fast-tracking plans for more animal-to-human procedures
The agency accepted the request on New Year’s Eve, and the surgery was performed on January 7 at the University of Maryland Medical Center in Baltimore, the center said.
“We’ve passed the Rubicon,” said Dr. Robert Montgomery, director of the NYU Langone Transplant Institute, on the first surgery of its kind. “We’re trying to figure that out and where to go next.” He was not involved in the surgery.
The Maryland center is one of several transplant centers that, according to Mr. Bennett’s son, David, had refused to list Mr. Bennett for the opportunity to receive a human heart because he would not be able to comply with doctors’ orders and attend follow-up visits. had failed to take. Bennett Jr. said that his father, who has a family history of heart disease, takes his medication “here and there,” but not consistently.
“It was a hard blow that he was turned down for a human heart, but at the same time I realized that the powers that be must have some objective criteria to determine who will be most successful with a heart,” said the younger Mr. Bennett said.
Bartley P. Griffith, professor of transplant surgery who performed the surgery, said transplant centers follow strict guidelines when deciding who is eligible for a heart transplant. Due to the scarcity of human hearts and other organs, the center addresses social issues such as family support and the ability and willingness of patients to follow lifelong medication regimens necessary to ensure that the organ remains healthy after transplant.
In the case of the elder Mr. Bennet, “we cannot give them the treasure that is the human heart,” Dr. Griffith said, adding that the availability of pig hearts opened up a potentially life-saving opportunity. “We will make sure he is obedient and doing his best,” he said. “We will visit the house if need be.”
Surgeons performed more than 41,000 organ transplants in the U.S. last year, according to the United Network for Organ Sharing, a record-setting number, the nonprofit that helps allocate organs under contract with the federal government. A spokesman for the network said more than 100,000 patients are on the waiting list for a donor organ at any given time, and more than 6,000 patients die each year before getting one.
To address the shortfall, researchers have been trying for decades to develop an organ transplant between different species, or xenotransplantation.
The practice was largely abandoned in the 1980s, when an infant with a fatal heart condition, known as Baby Fay, died within a month of being given baboon hearts.
Another push by companies and scientists faltered in the 1990s after experiments with nonhuman primates showed that the animals’ immune systems attacked and rejected pig organs, which are similar in size and function to humans. .
Advances in gene editing and cloning techniques have revived hopes in recent years that clinical trials of xenotransplantation may be possible. Researchers reported in 2015 that they had used Crisp, a new gene-editing technique, to inactivate pig viruses that might otherwise infect humans transplanted with pig organs.
A baboon that was transplanted a genetically modified pig heart lived for nine months, said Dr. Muhammad Mohiuddin, a professor of surgery at the University of Maryland who helped establish the university’s cardiac xenotransplantation program.
Revivicor, Blacksburg, VA, the company that provided the pig whose heart was given to the elder Mr. Bennett, made genetic changes to the heart to make it more compatible with the human body, which may have involved inactivation of a gene that caused the organ to die. May have triggered rejection.
Many xenotransplantation researchers have spent decades trying to gather enough data to advance experiments and justify clinical trials in humans.
“It’s hard to find,” said Dr. Montgomery, adding that researchers are conducting experiments on nonhuman primates, with the goal of showing that a human patient given a pig kidney can live at least two years after surgery. can expect.
Many doctors in this field think that nonhuman primate studies have progressed as far as they can and the only way to determine whether pig organs will work in humans is to transplant them, Dr. Montgomery said. In December, his team attached a genetically modified pig kidney to the upper leg of a deceased patient who had been put on a ventilator. Dr. Montgomery said the kidney functioned normally for more than 54 hours and showed no signs of rejection.
The researchers said more studies are needed before clinical trials involving pig kidney transplants can begin. Dr. Montgomery said the next phase is likely to involve attempting to keep the kidneys working for longer, possibly several weeks.
The transplant in Maryland raises questions about whether patients will have access to animal organs and what risks patients will face if clinical trials go ahead, said a research scholar at Hastings Center, Garrison, NY. According to a Bio-ethics Research Institute in A procedure by itself does not mean that it is going to be a safe and effective intervention,” she said. “We have to make sure we get good evidence that the risk humans are taking is worth taking.”
To study the ethical and policy issues arising from experimental animal-to-human transplantation, Dr. Maschke has a National Institutes of Health grant.
Maryland transplant could prompt doctors to expedite clinical trials, Dr. Montgomery said he is considering whether to request emergency authorization from the FDA to transplant a pig kidney into a dying patient who has no other option.
Dr. Griffith said the University of Maryland team is working with other academic centers on a plan to gain FDA approval to begin clinical trials of pig heart transplants. “Right now we are concerned about taking care of this patient,” he said of the elder Mr. Bennett, adding that plans could take a year or more.
The younger Mr Bennett, 37, said he was experiencing heart trouble and that he understood his father’s precarious health. “I would love for my father to live for a year or more,” he said. “I also know that this transplant offers hope to many people. What he is doing now can help change what happens in my own future as well.
Write Amy Docker Marcus at [email protected]