The first man to ever receive a heart transplant from a pig has died two months after the revolutionary operation took place.
David Bennett, 67, died on Tuesday at the University of Maryland Medical Centre, the hospital announced.
A cause of death has not yet been provided by doctors in the United States, who have only stated that his condition had been deteriorating over the past few days.
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Mr Bennett's son praised the hospital for offering the experimental operation and said the family hopes it will help continue efforts to end the organ shortage.
“We are grateful for every innovative moment, every crazy dream, every sleepless night that went into this historic effort,” David Bennett Jnr said in a statement released by the University of Maryland School of Medicine.
“We hope this story can be the beginning of hope and not the end.”
Mr Bennett, a handyman from Hagerstown, was a candidate for the new operation of transplanting a pig's heart because doctors had no doubt he would have died without it.
Following the operation, which took place on January 7, Mr Bennett's son said his father knew there was no guarantee he would survive as a result of the transplant
Prior attempts at such transplants – or xenotransplantation – have failed largely because patients’ bodies rapidly rejected the animal organ.
This time, the Maryland surgeons used a heart from a gene-edited pig.
The pig gene from the organ was removed via modification and then replaced with human genes.
Slowly, Mr Bennett seemed to be recovering and taking to the new heart. Video footage was released last month of him watching the Super Bowl in bed.
Mr Bennett survived significantly longer with the gene-edited pig heart than one of the last milestones in xenotransplantation – when Baby Fae, a dying California infant, lived for 21 days with a baboon’s heart in 1984.
“We are devastated by the loss of Mr Bennett. He proved to be a brave and noble patient who fought all the way to the end,” Dr Bartley Griffith, who performed Mr Bennett’s surgery, said in a statement.
Currently, there is a major shortage of organs with medical professionals searching for another source.
But more than 106,000 people remain on the waiting list in the US, thousands die every year before getting an organ and thousands more never even get added to the list, considered too much of a long shot.
The Food and Drug Administration (FDA) had allowed the dramatic Maryland experiment under “compassionate use” rules for emergency situations.
Mr Bennett’s doctors said he had heart failure and an irregular heartbeat, plus a history of not complying with medical instructions.
He was deemed ineligible for a human heart transplant, which requires strict use of immune-suppressing medicines, or the remaining alternative, an implanted heart pump.
Doctors didn’t reveal the exact cause of Mr Bennett’s death. Rejection, infection and other complications are risks for transplant recipients.
But from Mr Bennett’s experience, “we have gained invaluable insights learning that the genetically modified pig heart can function well within the human body while the immune system is adequately suppressed,” said Dr Muhammad Mohiuddin, scientific director of the Maryland university’s animal-to-human transplant programme.
Concerns are being raised about whether enough was learned from Mr Bennet's transplant to persuade the FDA to allow a clinical trial involving other potential organs such as kidneys.
Twice last autumn, surgeons at New York University got permission from the families of deceased individuals to temporarily attach a gene-edited pig kidney to blood vessels outside the body and watch them work before ending life support.
And surgeons at the University of Alabama at Birmingham went a step further, transplanting a pair of gene-edited pig kidneys into a brain-dead man in a step-by-step rehearsal for an operation they hope to try in living patients possibly later this year.
Pigs have long been used in human medicine, including pigskin grafts and implantation of pig heart valves.
But transplanting entire organs is much more complex than using highly processed tissue.
The gene-edited pigs used in these experiments were all provided by Revivicor, a subsidiary of United Therapeutics. They are one of several biotech companies spearheading the program to develop suitable pig organs for human transplant operations.
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