Scientists announced Wednesday they have restored blood flow and cell function in the bodies of pigs that had been dead for an hour. In a breakthrough, experts might say we need to update the definition of death itself.
The discovery raised hopes for a number of future medical uses in humans, the most immediate of which is that it could help organs last longer and potentially save the lives of thousands of people worldwide in need of transplants.
However, it could also spark debate about the ethics of such procedures – particularly after some of the supposedly dead pigs startled scientists with sudden head movements during the experiment.
The US-based team stunned the scientific community in 2019 when they managed to restore cell function in the brains of pigs hours after decapitation.
For the latest study, published in the journal Nature, the team attempted to extend this technique to the entire body.
They triggered a heart attack in the anesthetized pigs, which stopped the flow of blood through the bodies.
This deprives the cells of the body of oxygen – and without oxygen, cells in mammals die.
The pigs then sat dead for an hour.
– ‘Cell destruction can be stopped’ –
The scientists then pumped the bodies with a liquid containing the pigs’ own blood, plus a synthetic form of hemoglobin — the protein that carries oxygen in red blood cells — and drugs that protect the cells and prevent blood clots.
Blood began circulating again and many cells began functioning for the next six hours of the experiment, including in vital organs like the heart, liver and kidneys.
“These cells were working hours after they shouldn’t have been – what that tells us is that cell death can be stopped,” Nenad Sestan, the study’s lead author and researcher at Yale University, told reporters.
Co-lead author David Andrijevic, also from Yale, told AFP the team hopes the technique, called OrganEx, “can be used to save organs.”
OrganEx could also enable new forms of surgery because it creates “more medical latitude in non-circulatory cases to fix things,” said Anders Sandberg of the University of Oxford’s Future of Humanity Institute.
The technique could also potentially be used to resuscitate humans. However, doing so could increase the risk of returning patients to a point where they can no longer live without life support — caught on the so-called “bridge to nowhere,” said Brendan Parent, a bioethicist at NYU Grossman School of Medicine, in a linked comment in Nature.
– Could death be treatable? –
Sam Parnia of NYU Grossman School of Medicine said it was “a truly remarkable and incredibly meaningful study.”
It shows that death is not black and white, but a “biological process that remains treatable and reversible hours after it occurs,” he said.
Benjamin Curtis, a philosopher specializing in ethics at Britain’s Nottingham Trent University, said 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 in fact not irreversible, and so under the current medical definition of death, a person can only be truly dead hours after their bodily functions have ceased,” he told AFP.
“Indeed, if we accept the current definition as valid, there could currently be bodies lying in morgues that are not yet ‘died’.”
During the experiment, pretty much all of the OrganEx pigs made vigorous movements with their heads and necks, said Stephen Latham, a Yale ethicist and co-author of the study.
“It was pretty scary for the people in the room,” he told journalists.
He stressed 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” on the EEG machine, which measures brain activity, at the time of the movement, Latham said it was likely caused by the displacement of the head affecting the recording.
However, Curtis said the movement is a “big problem” as recent neuroscience research suggests that “conscious experiences can continue even when electrical activity in the brain cannot be measured.”
“So it’s possible that this technique actually caused the affected pigs to suffer and people would suffer if it were used on them,” he added, calling for more research.
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