The version used in Maryland came from a pig with 10 gene mutations made by Revivicar, a subsidiary of United Therapeutics.
Following the promised testing of such pig organs in baboons, three U.S. transplant teams began their first human research in late 2021. Surgeons at New York University and the University of Alabama each connect the pig kidneys of brain-dead people, but the University of Maryland. One step further when Griffith sewed a pig's heart into Bennett's chest in early January.
The transmission of the swine flu virus to humans was a matter of concern – some fear genotransplantation could trigger an epidemic if a virus adapts to a patient's body and then spreads to doctors and nurses. Anxiety can be severe enough to require lifelong monitoring for patients.
However, certain types of viruses found in Bennett's donor heart are not believed to be capable of infecting human cells, said Jay Fishman, a transplant infection specialist at Massachusetts General Hospital. Fishman thinks there is “no real risk to humans” of its further spread.
Instead, the problem is that pig cytomegalovirus is associated with reactions that can harm organs and the patient – with catastrophic consequences. Two years ago, for example, German researchers reported that transplanted pig heart virus in baboons lasted only a few weeks, while organs free from infection could live more than half a year.
The researchers said they found levels of “surprisingly high” virus in the hearts of pigs removed from the baboon. They believe that the virus could be spread not only by drug suppression of baboon immunity, but also by the fact that pigs no longer have the immune system to control the virus. It seems that the same thing could happen to humans, “they warned at the time.
University of Maryland School of Medicine
Joachim Dener of the Institute of Virology at the Free University of Berlin, who led the study, said the solution to the problem was a more accurate test. The U.S. team appears to have tested pig saliva for the virus, but it is often hidden deep in tissues.
“It's a latent virus and difficult to detect,” Dener said. “But if you examine the animal better, it won't happen. The virus can be detected and easily removed from the pig population, but unfortunately they did not use a good test and could not detect the virus, and this was the reason. The donor pig was infected and the virus was transmitted through transplantation. “
Denner said he still thinks the test was a “great success.” In 1967, for example, the first human-to-human heart transplant lasted only 18 days, and two years later, in Germany, it lasted only 27 hours.
Dener said the virus alone could not be blamed for Bennett's death. “This patient was very, very, very sick. Don't forget that, “he said.” Maybe the virus did contribute, but it wasn't the only reason. “
The cause of death?
The cause of Bennett's death is important, because if his heart failed due to rejection of immunity, the researchers would have to return to the drawing board. Instead, it is now expected that educators at United Therapeutics and Egensis, or those working with them, will begin clinical trials of their pig organs in a year or two.
Bennett was offered a pig's heart after Griffith once applied to the US Food and Drug Administration for special permission to try an animal organ in a transplant. He was considered a good candidate for the courageous endeavor because he was close to death from heart failure and was ineligible for a rare human heart for replacement due to his history of ignoring medical advice.
