In 1964, surgeon James Hardy performed the first heart transplant in history. That 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 make possible the use of animal organs in humans, but so far have not overcome technical difficulties. Today, in the magazine Nature, scientists from the University of Munich explain how they managed to get two baboons to survive three months with a porcine heart in their chest and two more to reach six before being slaughtered. These results, which multiply by more than three the previous record of 57 days of survival, approach the possibility of converting pigs into a source of hearts to transplant humans who need them.
When a person has a terminal heart disease, transplantation is the only durable solution and pigs would be an option in the face of a shortage 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 the baboons and not suffer from the rejection of their immune system. In addition, the monkeys were treated to suppress their defenses and ensure a good reception. These types of treatments, which are commonly used in transplants, increase the risk of dangerous infections, which did not occur in this experiment.
Another step that can 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 solution refrigerated with oxygenated blood, nutrients and hormones. In the first part of the experiment, which was carried out in three phases, the scientists observed that pig hearts grew inside the baboons until they died a little more than a month after the operation. To avoid the problem, they reduced the blood pressure of the monkeys, which is higher than that of the pigs, until reaching the optimum level for their new hearts, and pharmacological and hormonal treatments were applied to avoid excessive cardiac development.
Cristina Costa, a researcher at the Biomedical Research Institute of Bellvitge (IDIBELL), in Barcelona, and a specialist in this type of transplants between species, points out that this "field was a bit stuck due to the lack of a good animal model and this study establishes one new "to bring these techniques to trials with humans. "It needed a good animal model to test the organs that are generated in these pigs modified with the new genomic editing technologies," he concludes.