Heart transplants don’t usually make the headlines around the world. But earlier this month, a 57-year-old man with end-stage heart failure was the first to receive a heart transplant from a very special source: a genetically modified pig.
Of all the testimonies so far, the man, David Bennett, it seems to be going well.
These aren’t the first cases of pig tissue transplants in humans — not by a long shot.
Heart valves from pigs, cows and horses have been transplanted into human hearts for 30 years.
But whole organ transplants are a different ball game, both technically and ethically.
So what are some of these ethical dilemmas around the practice of cross-species organ and tissue transplantation – a technique called xenotransplantation – and can we expect to see pig hearts in chests in Australia soon?
Ethical issues and material issues
University of Sydney bioethicist Diego Silva said xenotransplantation and growing replacement parts in animals such as pigs raises a series of ethical questions.
“We are genetically modifying pigs, in this case, and using them as a tool to benefit humans,” he said.
“But we have to recognize that all of this is happening against the background of organ shortages. People are dying.
“We don’t see if we can [transplant pig organs into humans] because it’s interesting, but we’re doing this to save lives.”
Julian Koplin, a bioethics researcher at the University of Melbourne and Monash University, said ethical considerations could be broadly divided into human and animal welfare issues.
The first, and perhaps the most obvious, is that a heart taken from a pig may save a person’s life, but it means death for the donor.
“We are currently raising and killing pigs – sometimes in factory-farmed conditions, which are quite horrific – so that we can enjoy a tasty source of protein,” Dr Koplin said.
Then there is the quality of life of the donor pig. Pigs are intelligent and social creatures.
Donor pigs are bred and raised in medical grade facilities to protect them from diseases that can be transmitted to humans.
“And that means the life of a transplanted pig might not have a lot of opportunities for environmental enrichment,” Dr. Koplin said, compared, for example, to a pig allowed to sniff on a farm.
“But again, the purpose it serves is critically important, so it’s potentially a trade-off worth making.”
On the human side, while Mr Bennett’s nine-hour operation was performed by transplant surgeons in a hospital, it’s important to remember that this is still an experimental procedure.
“What kind of consent standards are needed to test the technology, and who should be eligible? says Dr. Koplin.
In Mr. Bennett’s case, it was either a transplant of a pig’s heart or death. He suffered from end-stage heart disease, but was not eligible for a human heart transplant.
“The worst-case scenario if he participates in this experimental treatment is not much worse than the expected scenario if he does not.”
Then, if the technique eventually transitions into more mainstream clinical care, further questions will be raised about historical health disparities – will it make health care more or less equitable for minority populations? — not to mention how the animal organ transplant business will work, Dr. Silva said.
“And what are regulators going to want to see to say, ‘yes, those are the parameters by which you can increase that’?”
“To a large extent this is a scientific question, but there is also an ethical aspect. What risks are we willing to take?”
What’s the deal in Australia?
Transplantation of organs from pigs and other animals has a long history dating back to the middle of the last century.
And although clinical trials are now permitted in Australia, subject to regulatory approvals, this has not always been the case.
From 2004 to 2009, the National Health and Medical Research Council (NHMRC) recommended that clinical trials of xenotransplantation should not be conducted in Australia “as this was still a developing area of science”.
A major concern was the risk of spreading disease between pigs and humans. That’s because your standard, ordinary pig DNA doesn’t just contain instructions for building the pig.
It also contains the genetic code for a bunch of viruses, some of which can infect human cells where they could cause disease and spread.
In recent years, gene-editing techniques such as CRISPR have allowed researchers to remove this viral DNA from a pig’s genome, resulting in virus-free animals.
They can also add and remove genes to reduce the risk of organ rejection.
The biggest scientific hurdle to overcome today is preventing the human body from rejecting the transplanted organ, according to Peter Cowan, scientific director of the Center for Immunology Research at St Vincent’s Hospital in Melbourne.
But even if that problem were solved tomorrow, we wouldn’t see whole pig organ transplants or even human clinical trials happening in the short to medium term, said Professor Cowan, who is involved in research on pig-to-human xenotransplantation. .
“Due to our quarantine rules, we cannot import live pigs. We couldn’t say ‘OK, let’s take pigs from the United States and bring them here and start doing transplants'”.
Then there is the issue of where we would keep them, even if the pigs could be brought in, he added. In Australia, we don’t have medical-grade pig facilities – needed for human clinical trials – and they’re expensive to set up and run.
Still, the pig heart transplant “has really sparked interest across the region”, Professor Cowan said.
“I hope it takes off. We really want things to settle down here in Australia as well.”
According to Dr. Silva, as advances in whole-organ xenotransplantation continue, discussions about ethics and regulation will also continue.
“It’s not going to be so much about asking, ‘Is this the right thing to do?'” he said.
“It’s more, ‘how can we do this the right way?’ And that should be the guiding question.”