Health & Fitness

Does future of medicine rest on animal organs being used in humans?

pig-heart

A University of Maryland School of Medicine photo released on Monday shows surgeons performing a transplant of a heart from a genetically modified pig to patient David Bennett, Sr., in Baltimore, Maryland, on January 7, 2022. PHOTO | AFP

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Summary

  • On Monday this week, doctors said he was breathing on his own while still connected to a heart-lung machine to help his new heart and was doing well three days after the highly experimental surgery.
  • While it is too soon to know whether the ground-breaking surgery will really work, it marks a step in the decades-long quest to one day use animal organs for life-saving transplants in humans.
  • Doctors say that the transplant shows that a heart from a genetically modified animal can function in a human body without immediate rejection.

In the early 1970s, a family friend lost his eye in a freak accident. After the incident, he went in for surgery and came out with what he claimed was a goat’s eye. It sure didn’t look like the usual human eye, but he popularised the story of the goat’s eye.

He still has that eye today, but we have never ascertained the veracity of his claim. However, we gave him the benefit of the doubt and recent advances in medicine could very well justify his claim.

This week I read the news of the first transplantation of a pig’s heart into a human, David Bennett, 57, a man so sick that regulators granted exceptional approval to doctors attempting to save his life with the procedure.

It will be recalled that in 1960, South African surgeon, Christiaan Barnard took a buccaneering approach to organ transplantation. In what many thought was a vain and reckless operation, he added a second head to a dog.

However, just seven years later, he achieved global celebrity by performing the world’s first human heart transplant.

In the latest procedure, doctors at the University of Maryland Medical Centre in the United States, transplanted a pig’s heart into a patient in a last-ditch effort to save his life.

On Monday this week, doctors said he was breathing on his own while still connected to a heart-lung machine to help his new heart and was doing well three days after the highly experimental surgery.

While it is too soon to know whether the ground-breaking surgery will really work, it marks a step in the decades-long quest to one day use animal organs for life-saving transplants in humans.

Doctors say that the transplant shows that a heart from a genetically modified animal can function in a human body without immediate rejection.

The dawn of the xenotransplant era was in 1838, when Dr Richard Kissam, an ophthalmologist in New York, cut out the opaque cornea from a sensationally brave Irishman and replaced it with one from a six-month-old pig, attached with two stitches.

Immediate results were encouraging but within two weeks the cornea clouded over. That was 67 years before the first human cornea transplant, performed by Dr Eduard Zirm on a labourer blinded in an accident. This time, as if by magic, the patient fully regained, and kept his sight.

It was not until 1954 that the first major human organ transplant of the kidneys took place. In 1963, a patient survived for nine months after receiving chimpanzee kidneys. A year later, Dr James Hardy performed the first chimpanzee-human heart transplant. His patient lasted just two hours.

Prior attempts at xenotransplantation have failed largely because patients’ bodies have rapidly rejected the animal organ. Notably, in 1984, Baby Fae, a dying infant, survived 21 days with a baboon heart.

Indeed, the apes, which most resemble us, remain the most suitable animal organ donors. Non-human primates are the best donors but, there is a major ethical constraint.

Some are endangered while others have long pregnancies producing one or two offspring. Pigs, on the other hand, have shorter gestation periods and produce up to a dozen offspring.

And, of course, some of us already eat them, hence pigs have become the donor of choice and the subject of decades of research, which only entrenches their use in future xenotransplantation study.

For those feeling squeamish at the idea of implanting animal organs in humans, Dr Reichart offers reassurance saying “There is no stigma. There should be no ethical concerns.” And in any event, he adds, the heart in question is not really a pig’s heart, which would be identified and rejected immediately. “You need to humanise a porcine heart”, he says, “Which means it is half-human, half-pig.”

That process of humanisation involved 10 genetic modifications of the pig heart, nine of which tweaked it to become more acceptable to the human body. The last process kept the heart small, just the right size for a person.

Pig heart valves have been used for decades successfully in humans, and Bennett’s son said his father had received one about a decade ago. As for the heart transplant, “He realises the magnitude of what has been done”, David Bennett Jr said, “He could not live, or he could last a day, or he could last a couple of days. I mean we are in the unknown at this point.”

There is a colossal shortage of human organs donated for transplant worldwide driving scientists to try to figure out how to use animal organs instead. Last year, there were 3,800 heart transplants in the US alone, a record number.

It will be crucial to share the data gathered from this transplant before extending it to more patients.

Nonetheless, when it comes to pig transplants, a new frontier has been irrevocably crossed.