A 57-year-old patient with terminal heart disease has become the first person in the world to receive a heart transplant from a genetically-modified pig, and is still doing well three days later.
The organ transplant demonstrated for the first time that a genetically-modified animal heart can function as a human heart without immediate rejection by the body.
The patient, David Bennett, a Maryland resident, had been deemed ineligible for a conventional heart transplant at several transplant centres that reviewed his medical records.
Bennett said: “It was either die or do this transplant. I want to live. I know it’s a shot in the dark, but it’s my last choice.
“I look forward to getting out of bed after I recover.”
The surgery was conducted by the University of Maryland School of Medicine (UMSOM) faculty at the University of Maryland Medical Center (UMMC), together known as the University of Maryland Medicine.
The U.S. Food and Drug Administration granted emergency authorisation for the surgery on New Year’s Eve through its expanded access (compassionate use) provision.
It is used when an experimental medical product is the only option available for a patient faced with a serious or life-threatening medical condition. The authorization to proceed was granted in the hope of saving the patient’s life.
Dr Bartley Griffith, professor in transplant Surgery at UMSOM and director of the cardiac transplant program at UMMC, surgically transplanted the pig heart into the patient.
He said: “This was a breakthrough surgery and brings us one step closer to solving the organ shortage crisis.
“There are simply not enough donor human hearts available to meet the long list of potential recipients.
“We are proceeding cautiously, but we are also optimistic that this first-in-the-world surgery will provide an important new option for patients in the future.”
One-hundred-and-ten-thousand Americans are currently waiting for an organ transplant, and more than 6,000 patients die each year before getting one.
Xenotransplantation could potentially save thousands of lives but does carry a unique set of risks, including the possibility of triggering a dangerous immune response. These responses can trigger an immediate rejection of the organ with a potentially deadly outcome to the patient.
Xenotransplants were first tried in the 1980s, but were largely abandoned after the famous case of Stephanie Fae Beauclair (known as Baby Fae) at Loma Linda University in California.
The infant, born with a fatal heart condition, received a baboon heart transplant and died within a month of the procedure due to the immune system’s rejection of the foreign heart.
However, for many years, pig heart valves have been used successfully for replacing valves in humans.
Organs from genetically modified pigs have been the focus of much of the research in xenotransplantation, in part because of physiologic similarities between pigs, humans, and nonhuman primates.
Revivicor, a regenerative medicine company based in Blacksburg, VA, provided the genetically-modified pig to the xenotransplantation laboratory at UMSOM.
Three genes, responsible for rapid antibody-mediated rejection of pig organs by humans, were ‘knocked out’ in the donor pig.
Six human genes responsible for the immune acceptance of the pig heart were inserted into the genome. Lastly, one additional gene in the pig was knocked out to prevent excessive growth of the pig heart tissue, which totalled 10 unique gene edits made in the donor pig.
On the morning of the transplant surgery, the team removed the pig’s heart and placed it in the XVIVO Heart Box, a perfusion device, a machine that keeps the heart preserved until surgery.
The team also used a new drug along with conventional anti-rejection drugs, which are designed to suppress the immune system and prevent the body from rejecting the foreign organ.
Dr Christine Lau, professor and chair of the Department of Surgery at UMSOM and surgeon-in-chief at UMMC said the surgery has the potential to eliminate the organ shortage crisis.
“As a cardiothoracic surgeon who does lung transplants, this is an amazing moment in the history of our field.
“Decades of research here at Maryland and elsewhere have gone into this achievement. This has the potential to revolutionise the field of transplantation by eventually eliminating the organ shortage crisis.
“This is a continuation of steps to making xenotransplantation a life-saving reality for patients in need.”