Raising the dead sounds like science fiction, but a team of Yale University medical scientists has done just that—at least on a cellular level.
According to a Nature study published on August 3, they successfully revived cells from pigs that had been dead for an hour. While the authors of the study emphasize that the technology is still years away from being used on humans, the work could eventually help keep human tissues alive longer, increasing the supply of viable organs for transplants.
“These cells are functioning hours after they should not be,” said Nenad Sestan, a professor of neuroscience and comparative medicine at Yale and the lead author of the study. “And what this tells us is that the demise of cells can be halted. And their functionality is restored in multiple vital organs. Even one hour after death.”
Sestan and his colleagues received 100 pigs from a local breeder. They placed the pigs on ventilators and shocked the animals’ hearts to induce cardiac arrest. An hour after confirmed death, the Yale scientists used two systems to pump blood back into the bodies—an ECMO machine removed carbon dioxide and added oxygenated blood to one group, while another device, called OrganEx, pumped artificial blood back into the other. That fluid entered the blood vessels of the dead pigs, where synthetic forms of hemoglobin and other molecules protected cells from degradation and stopped blood clots.
After six hours, the researchers recorded signs of oxygen recirculating into the pigs’ tissues. A heart scan confirmed signs of electrical activity in the heart of pigs on the OrganEx machine, though those organs did not fully restart. Elsewhere, there were signs of business as usual, too: The livers of the deceased pigs resumed production of a protein called albumin. Additionally, the cells of other vital organs were responsive to glucose, suggesting the pigs’ metabolic processes were working again.
Studies such as these raise questions about what it means to be dead. “We presume death is a thing, it is a state of being,” said Nita Farahany, a Duke law professor who studies ethical, legal, and social implications of emerging technologies. “Are there forms of death that are reversible? Or not?”
The findings also call into question who is legally dead, especially as medicine evolves to make cardiac death reversible one day. “People tend to focus on brain death, but there’s not much agreement on when cardiac death occurs,” said New York University bioethicist Arthur Caplan. “This paper emphasizes that in a significant way.”