The pigs had been dead an hour when researchers at Yale University circulated a nutrient-rich fluid through their bodies. After six hours, some cells in the pigs’ organs showed signs of functioning again. Cellular activity returned to places in their hearts, livers, kidneys and brains. The pigs were not brought back to life–they didn’t display any brain activity that could be interpreted as the animals regaining consciousness, reports Nature News’ Max Kozlov. But the findings, which were published last week in the journal Nature, challenge the notion that cardiac death can’t be reversed, according to Wired.
The researchers hope the finding is an early step in the effort to be able to make more human organs available for transplant long after death, writes Gina Kolata for the New York Times. But such applications are still a ways off. The technology the researchers used is “very far away from use in humans,” Stephen Latham, a bioethicist at Yale University who worked closely with the researchers, tells the Times.
The study highlights the idea that death is not a moment but a process, Arthur Caplan, a bioethicist at New York University who was not involved in the study, tells Nature News.
The researchers conducted a similar experiment in 2019, connecting the heads of dead pigs to a system that circulated a fluid through the pigs’ brains, writes Brendan Parent, the director of transplant ethics and policy research at New York University’s Grossman School of Medicine, in a commentary about the new research published in Nature. The pigs had been decapitated for food production four hours prior, but the researchers were able to revive the activity of some brain cells. At the time, University of Pennsylvania bioethicist Jonathan Moreno, who was not affiliated with the research, told the Times that “if ever there was an issue that merited big public deliberation on the ethics of science and medicine, this is the one.” The findings blurred the line between what it means for a brain to be alive versus dead and raised questions about how patients who have experienced extensive brain damage should be treated.
The study raises ethical questions, particularly if the system is one day used to restore brain activity after death, Dr. Nita Farahany, a neuroethicist at Duke University, tells Nature News. The Times noted that the solution the researchers used included nerve blockers that would ensure the brain was not active during the experiment.
Dr. Deepali Kumar, president of the American Society of Transplantation and professor of medicine at the University of Toronto, tells Wired’s Emily Mullin that the system could eventually be used to make more human organs available for transplant. “There is a significant shortage of organs for transplantation, and we certainly need new technologies that can help improve the organ supply,” she says.
There are around 106,000 people in the U.S. on the national transplant waiting list, and 17 people die each day waiting for a transplant, according to Wired.