In 1964, surgeon James Hardy performed the first heart transplant in history. This operation was also the first in which the heart of an individual of one species was placed in another because the involuntary donor was a chimpanzee. The human being who tried to save his life did not survive two hours after the intervention. Since then, surgeons and scientists have tried to develop methods to enable the use of animal organs in humans, but so far have not overcome technical difficulties. Today, in the magazine Nature, scientists at the University of Munich explained how they got two baboons to survive three months with a heart of swine in the chest and two more to get to six before being slaughtered. These results, which multiply by more than three the previous record of 57 days of survival, address the possibility of converting pigs into a source of hearts for the transplantation of humans who need them.
When a person has terminal heart disease, transplantation is the only durable solution and the pigs would be a choice in the face of a lack of human donors. However, making the organ of one species work in another is not easy. First, the authors of this work used genetically modified pigs to make their hearts resemble those of baboons and not suffer rejection of their immune system. In addition, the monkeys were treated to suppress their defenses and ensure a good reception. These types of treatments, commonly used in transplants, increase the risk of dangerous infections, which did not occur in this experiment.
Another step that may explain the success of the team coordinated by Bruno Reichart of the University of Munich is the system to maintain the integrity of the organ during the process. Instead of keeping the heart cold, they pumped a refrigerated solution with oxygenated blood, nutrients and hormones. In the first part of the experiment, which was carried out in three phases, the scientists observed that the hearts of the pigs grew inside the baboons until they died a little more than a month after the operation. To avoid the problem, they reduced monkey blood pressure, which is greater than that of pigs, until reaching optimal levels for new hearts, and pharmacological and hormonal treatments were applied to prevent excessive cardiac development.
Cristina Costa, a researcher at the Institute of Biomedical Research of Bellvitge (IDIBELL) in Barcelona, and specialist in this type of transplant between species, points out that this "field was a bit stuck due to the lack of a good animal model and this study establishes a new "to bring these techniques to trials with humans. "I needed a good animal model to test the organs that are generated in these pigs modified with the new technologies of genomic editing," he concludes.