Doctors transplant pig heart to human

It took the surgeons eight hours, but they managed to insert a pig’s heart into the 57-year-old patient’s chest. The heart of a pig resembles that of a human: it is about the same size and has the same heart rate. To prevent rejection of the organ, scientists modified the pig’s DNA (see box: ten mutations in the pig heart). So far that seems to work. Three days after surgery, the heart recipient was doing well, according to his doctors. They are cautiously optimistic and will continue to monitor the patient for the time being. But we can’t call it a success yet. “We can only speak of this if there are no complications in the coming months,” says Ian Alwayn, transplant surgeon at the LUMC.

Do not cheer to early

American surgeons perform the pig heart transplant to the 57-year-old man.

So we should not celebrate too early. “It’s only been a week since the transplant and anything can go wrong,” Alwayn said. For example, despite the genetic modification of the pig heart, the body can still reject the organ or infections can occur. Last year, doctors successfully transplanted a pig kidney into a brain-dead patient, but never before has a real patient received an animal organ. It is therefore difficult to predict what will happen in the near future.

Despite the positive media coverage, this is not the starting point for global pig heart transplants. The American patient suffered from life-threatening heart disease and was not eligible for a human donor heart and would soon die. Therefore, the patient agreed to the xenotransplantation as a last experimental resort. “Experimental treatments are more common,” Alwayn says. “Although you mainly see them in cancer patients and not so often in transplant patients.”

Ten mutations in the pig heart

The donor heart came from a healthy pig in which scientists modified ten genes. By genetically modifying the pig, the DNA in the organs, such as the heart, also changes. Scientists turned off three genes that normally lead to rejection. In addition, they added six human genes that should increase the chance of acceptance. Finally, they removed a piece of DNA from the pig to prevent overgrowth of the pig heart tissue.

If the patient continues to recover in the coming months, there is a good chance that doctors will continue xenotransplants in a research context. Doctors then test with a small group of transplant patients whether genetically modified animal organs are safe for the patient and the environment. In addition, such a study helps doctors better understand the transplantation of animal organs. These small-scale studies are the start of clinical studies. “Doctors have to follow patients for years, which means it will be quite some time before doctors perform xenotransplants on a large scale,” Alwayn said.

Ethical concerns and legislation

In the Netherlands this is not an issue for the time being. Unlike many other countries such as America, here we are not allowed to just transplant animal organs into humans and our legislation prohibits research into such xenotransplants. Those guidelines were drawn up twenty years ago, partly because of the rejection of animal organs in humans. Modern technology now reduces the chances of rejection. Still, that’s not just a reason to change the law, says Alwayn. “The question ‘do we want this?’ is at least as important as ‘can we do this?’”, says the transplant surgeon. Dutch society must think along about the ethical aspects behind it and give it a say.

“The regulations reflect the concerns in society,” says Eline Bunnik, medical ethicist at Erasmus MC. “It is important that politicians take the opinions and concerns of society into account in decision-making.” For this reason, NEMO Kennislink, in collaboration with the Rathenau Institute, among others, organized donor animal dialogues at various locations to enter into discussions about the ethical aspects of xenotransplants. The findings are bundled in a report.

Although the report is still in the works, the medical ethicist has already seen important points of view emerge. The responses were quite different from those ten and twenty years ago, when researchers surveyed citizens on the same subject. “Then the Yakkes factor played a bigger role,” says Bunnik. People felt hesitation or even revulsion about research into species mixing and objected on principle to genetically modifying animals. “During the 2021 dialogues, participants mentioned very different objections. Animal welfare was discussed in particular: some do not believe that medical emergency outweighs the interests of animals.”

Choose direction

“Looking back, the donor animal dialogues came at just the right time,” says Bunnik. “We now have an idea of ​​what concerns are at stake and can conclude this stage of public discussions.” However, Wageningen animal ethicist Bernice Bovenkerk thinks that the donor animal dialogue was just the beginning and that more public discussion is needed.

“In the donor animal dialogue, the starting point was: you choose an animal organ if that technology exists and has been approved,” says Bovenkerk. “But the current question is: should we develop the technology at all.” The news of the transplant in America is fueling the discussion, even among people who previously did not have a strong opinion about it. “As a society we now have to choose a direction: investing in research into donor animals or in research into alternative methods. There is still time: (animal) ethics have not lost yet”, says Bovenkerk.

For the time being, transplant patients are not yet rid of the long waiting lists. The transplantation of animal organs to humans must first prove successful, subject to clinical studies and to more social debate. And science may be very different in ten years’ time. Because it is not only xenotransplants that are developing, other technologies such as cultured organs, artificial hearts and stem cells to restore organs are also making strides. These may lead to alternative options that pose less ethical dilemmas.


Source: Kennislink by www.nemokennislink.nl.

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