PARIS, France (AFP) — Scientists announced on Wednesday that they had restored blood flow and cell function in the bodies of dead pigs for an hour. According to experts, a breakthrough could mean we need to update the definition of death itself.
This discovery raised hopes for a range 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 around the world in need. of transplants.
However, it could also spark debate over the ethics of such procedures – especially after some of the apparently dead pigs surprised scientists by jerking their heads during the experiment.
The American team from Yale University stunned the scientific community in 2019 by successfully restoring cell function in the brains of pigs within hours of their decapitation.
For the latest research, published in the journal Nature, the team sought to extend this technique to the whole body.
They caused a heart attack in anesthetized pigs, which prevented blood from circulating in the bodies.
This deprives the body’s cells of oxygen – and without oxygen, mammalian cells die.
The pigs then sat dead for an hour.
Scientists then pumped the bodies with a liquid containing the pigs’ own blood, along with a synthetic form of hemoglobin – the protein that carries oxygen in red blood cells – and drugs that protect cells and prevent clots blood.
Blood began to flow again and many cells began to function, including in vital organs such as the heart, liver and kidneys, for the next six hours of the experiment.
“These cells were working hours after they shouldn’t have been working – what this tells us is that the cells’ disappearance can be stopped,” Nenad Sestan, the study’s lead author, told reporters. researcher at Yale University.
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 make new forms of surgery possible because it creates “more medical leeway in cases without circulation to fix things,” said Anders Sandberg of the Future of Humanity Institute at the University of Oxford.
The technique could also be used to resuscitate people. However, it could increase the risk of dragging patients back to a point where they are unable to live without life support – trapped on what is called the “bridge to nowhere,” Brendan Parent, a bioethicist at NYU Grossman School of Medicine , said 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 significant study.”
It showed that death was not black or white but rather a “biological process that remains treatable and reversible for hours after it occurs”, he said.
Benjamin Curtis, a philosopher specializing in ethics at Nottingham Trent University in the UK, said the definition of death may need updating as it is based on the concept of irreversibility.
“This research shows that many processes that we thought were irreversible are in fact not irreversible, and therefore according to the current medical definition of death, a person may not be truly dead until hours after their bodily functions have stopped” , he told AFP.
“Indeed, there may currently be bodies lying in morgues that are not yet ‘dead’, if we take the current definition to be valid.”
During the experiment, almost all of the OrganEx pigs made powerful movements with their heads and necks, said Stephen Latham, Yale ethicist and co-author of the study.
“It was quite surprising to the people in the room,” he told reporters.
He pointed out that although it is not known what caused the movement, at no time was electrical activity recorded in the pigs’ brains, showing that they never regained consciousness after the dead.
Although there was a “little burst” on the EEG machine measuring brain activity at the time of movement, Latham said it was likely caused by head movement affecting the recording.
However, Curtis said movement was a “major concern” as recent neuroscience research has suggested that “conscious experience can continue even when electrical activity in the brain cannot be measured”.
“So it’s possible that this technique actually caused suffering to the pigs involved and could cause human beings to suffer if used on them,” he added, calling for more research.