Does genetically modified pig heart transplant offer hope for acute organ shortage?

The world’s first successful transplant of a pig’s heart into a human being has been carried out, giving hope to thousands of people desperately in need of replacement organs.

David Bennett, a 57-year-old handyman with life-threatening heart disease, had his heart replaced with a pig’s during an eight-hour operation in Baltimore, Maryland, on 7 January.

The pig had undergone gene-editing by scientists, who had removed a sugar in its cells to help reduce the risk of hyper-fast organ rejection. The fact that Bennett’s body didn’t immediately reject the genetically modified heart is thought to be extremely encouraging.

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Xenotransplantation – the transplantation of living cells, tissues or organs from one species to another – has failed in the past because of patients’ bodies rapidly rejecting the animal organ.

As the operation was only carried out last week, it is too soon to know whether it will be an overall success. However, Dr Bartley Griffith, the director of the cardiac transplant programme at the medical centre, said that Bennett’s new heart was “working and looks normal”.

“We are thrilled, but we don’t know what tomorrow will bring us,” he said. “This has never been done before.”

On 10 January, Bennett was breathing on his own while still connected to a heart-lung machine to help his new heart, said The Guardian. According to the paper, the next few weeks will be “critical” as doctors monitor how the heart fares post-surgery.

7,000 on UK waiting list

Every year, hundreds of people die when waiting for an organ transplant.

Figures from the NHS Organ Donor Register and National Transplant Register, which matches donors with those waiting for a transplant, show that while nearly 3,400 transplants were facilitated in 2020/21, 7,000 people remain on the Transplant Waiting List.

And in 2021 alone, more than 470 people died while waiting for a transplant.

Across the pond, the same issue exists. Last year, 41,354 Americans received a transplanted organ, but around a dozen people on the waiting list die per day, said The New York Times (NYT).

Pigs before primates

Pigs have advantages over primates when it comes to animal-human transplantations because they are “easier to raise and achieve adult human size in six months”, said the NYT.

Over the past three decades, pig heart valves have been successfully planted in humans and pig skin has also been used as a temporary graft for burn victims.

‘New era in medicine’

Researchers are now hoping that gene-editing will be the answer to future animal-to-human transplants. Last week’s operation could mark the beginning of what the paper described as a “new era in medicine in the future when replacement organs are no longer in short supply”.

Dr David Klassen, a transplant physician and the chief medical officer of the US United Network for Organ Sharing, described Bennett’s transplant as a “monumental event”, adding: “Doors are starting to open that will lead, I believe, to major changes in how we treat organ failure.”