A baboon survived 195 days after an experimental heart transplant. But the heart did not come from another baboon – it came from a pig.
There are far more people who urgently need organ transplants than donor organs are available – about 4,000 Americans are currently waiting for a heart. Scientists have suggested transplantation of organs between species or xenotransplants as a way to overcome this deficiency. This research will certainly stimulate some discussion, but is an important milestone.
"Transplantation prolongs life and adds a high, almost unrealistic quality of life, if you can," study author Bruno Reichart of LMU Munich in Germany told Gizmodo. So why not a heart [pig]? It is very similar to our own heart. "
Previous research has shown that xenotransplantation is quite difficult, and the only success the authors could find in their literature review was a single case of a baboon that survived 57 days. More recently, a baboon survived 945 days with a pig's heart connected to its circulatory system, although this heart did not replace the baboon's own heart.
In the latest study, baboons received genetically modified porcine heart transplants and received them an immunosuppressive drug to minimize the chances of their bodies rejecting the new heart. The first group of three baboons died shortly after the transplant; They had received hearts stored for two hours without blood. The researchers minimized the time the transplant heart was disconnected from the blood supply by connecting the organs to a mechanical pulmonary system that delivered nutrients. Three of the four baboons of this second group survived for 18, 27 and 40 days, but died because the hearts became too big. Pigs grow much faster than baboons, and the pig hearts do it too.
Finally, researchers lowered babies' blood pressure to that of pigs and gave them a drug called temsirolimus, which slows down heart growth. Of the five baboons of the third group, one died after 51 days from a blood clot. The four remaining survivors survived for 90, 90, 182, and 195 days, all of which were euthanized according to the previous approval and laboratory animal guidelines. Only one baboon surviving 182 days showed signs of heart failure, according to the study published in Nature.
A researcher who was not involved in the study, Muhammad Mohiuddin, a professor of surgery at the University of Maryland's School of Medicine, told Gizmodo that research is very important and was first shown to be one genetically manipulated pig heart supports a baboon for six months. He noted, however, that one of the CD40 antibodies used in the study had not yet been approved by the FDA. He wondered what other chemicals were in the solution that kept the heart alive outside the pig, and what role it played.
You will find that many baboons died in the course of the study. A medical ethicist, Carolyn Neuhaus of the Hastings Center Bioethics Research Institute, told Gizmodo that ethics committees require "humane endpoints" to make sure the animals are not in too much pain. These reviews will examine whether research really pays off for humans. In this study, the researchers do not tinker with baboons for fun, but try to find a solution that could save lives. Such a study is ethical only if researchers adhere to pre-approved guidelines. Reichart told Gizmodo that the study followed the advice of an advisory panel that the animals were kept busy and that the primatologists involved in the study believed the animals behaved normally after heart transplantation.
Studying should let us think about the future. Are we ready to feed pigs industrially, not only for meat, but also for their organs? Are we ready to link two already suspicious industries, pharmaceuticals and livestock?
And finally, the researchers state that they have demonstrated a "consistent survival of life-sustaining pig hearts" that meets the requirements of a report from the International Society for Heart and Lung Transplantation. However, this report was written in 2000.
"What the report was based on 18 years ago has almost definitely changed," said Neuhaus. "There is a zeal in the paper that may need to be tested against the current state [scientific understanding] and how best to protect humans in a groundbreaking and very risky research." willing to try to transplant pig hearts into humans – and further discussions about the ethics of the practice. But such a future may not be so far away.