A team of scientists announced this Wednesday (3) that they have managed to restore blood flow and cellular function throughout the body in pigs that had been dead for an hour, in an advance that some experts believe could lead to the update of the very definition of death.
The researchers restored circulation and cellular activity in the pigs’ vital organs, such as the heart and brain, within an hour of the animals’ death. The research challenges the idea that cardiac death – which occurs when blood circulation and oxygenation stop – is irreversible and raises ethical questions about the definition of death.
The finding holds out hope for a number of future medical uses in humans, the most immediate being that it could help organs last longer, potentially saving the lives of thousands of people in need of transplants.
However, it may also spur debate on the ethics of such procedures – particularly after some of the ostensibly dead pigs startled investigators with sudden head movements during the experiment.
The US-based team had already surprised the scientific community in 2019 by managing to restore cell function in the brains of pigs hours after they were decapitated.
For this latest research, published in the journal Nature, the team sought to expand this technique to the entire body.
The researchers induced a heart attack in the anesthetized pigs, which stopped blood from flowing through the bodies, depriving the cells of oxygen – and without oxygen, mammalian cells die. The pigs were dead for an hour.
“Cell death can be stopped”
The scientists then pumped into the animals’ bodies a liquid containing the pigs’ own blood, as well as a synthetic form of hemoglobin – the oxygen-carrying protein in red blood cells – and drugs that protect the cells and prevent blood clots.
The blood began to circulate again and many cells began to function, including in vital organs such as the heart, liver and kidney, during the six hours following the experience.
“These cells were functioning hours later than they were supposed to – what that tells us is that cell death can be stopped,” said Nenad Sestan, senior author of the study and a researcher at Yale University. Co-author David Andrijevic, also from Yale, told AFP the team hopes the technique, called OrganEx, “can be used to save organs.”
OrganEx may also enable new forms of surgery, as it creates “more medical wiggle room to resolve cases where blood flow has stopped,” said Anders Sandberg of the Future of Humanity Institute at the University of Oxford.
The technique could also theoretically be used to resurrect people. However, this can increase the risk of bringing patients back to a point where they are unable to live without life support.
Can death be treated?
Sam Parnia of the NYU Grossman School of Medicine describes this as “a truly remarkable and incredibly significant study” that has shown that death is not black and white, but rather a “biological process that remains treatable and reversible for hours after having occurred”.
For Benjamin Curtis, an ethics-focused philosopher at Nottingham Trent University in the UK, the definition of death may need updating because it depends on the concept of irreversibility. “This research shows that many processes that we thought were irreversible are not in fact irreversible, and therefore, under the current medical definition of death, a person may not actually be dead until hours after their bodily functions have stopped,” he told AFP.
“In fact, there may be bodies in morgues now that haven’t ‘died’ yet, if we take this definition to be valid.”
During the experiment, virtually all of the OrganEx pigs made sharp head and neck movements, said Stephen Latham, a Yale ethicist and co-author of the study. “It was quite surprising to the people in the room.”
The researcher emphasized that although it is not known what caused the movement, at no time was any electrical activity recorded in the pigs’ brains, showing that they never regained consciousness after death. While there was a “small burst” in the EEG machine that measures brain activity at the time of movement, Latham said this was likely caused by the dislocation of the head affecting the recording.
However, Curtis says the movement raises “great concern” because recent research in neuroscience suggests that “conscious experience can continue even when electrical activity in the brain cannot be measured.”
“So it is possible that this technique did in fact cause the pigs in question to suffer, and would cause humans to suffer if used on them,” he added, calling for further investigation.
Source: With Agencies