Science

Cells and organs of dead pigs “come to life” in a few hours

Scientists were able to restore circulation and function within hours of cells from the bodies of pigs that had died shortly before, according to a study that offers hope for medical applications but also raises ethical questions. In 2019, a US team of researchers stunned the scientific community by successfully restoring the function of pig brain cells hours after they were decapitated.

In their latest study, published Wednesday in the journal Nature, the same scientists sought to extend the technique to the entire animal body. They caused heart attacks in anesthetized pigs, which led to a cessation of blood flow and deprivation of their cells of oxygen – without oxygen, mammalian cells die. Then, an hour later, they injected the corpses with a fluid containing pig blood (taken from the living) and a synthetic form of hemoglobin, the protein that carries oxygen in red blood cells. As well as drugs that protect cells and prevent the formation of blood clots. Blood began to flow again and many cells began to function again, including those in vital organs such as the heart, liver and kidneys, over the next six hours.

Death, “reversible process”?

“These cells were running a few hours later than they were supposed to be. This shows that the disappearance of cells can be stopped,” said Nenad Sestan, lead author of the study and researcher at Yale University. Thus, under a microscope, it was difficult to distinguish between a normal and healthy organ and a post-mortem organ, added David Andrievich, co-author of the study, also from Yale University.

The team hopes this method, called OrganEx, can be used to “preserve organs” by extending their function, he explained. Which potentially saves the lives of people awaiting transplants. According to Anders Sandberg of the University of Oxford, OrganEx can also enable new forms of surgery, giving “more medical leeway.”

But this technique raises a number of questions, medical, ethical, even philosophical. This could “increase the risk that resuscitated individuals will not be able to come out of a state of life support,” warned Brendan Parent, a bioethicist at New York University’s Grossman School of Medicine, in a comment published in parallel with Nature.

According to Sam Parnia of the same university’s School of Medicine, this “really remarkable” study also shows that “death is a biological process that can be treated and is reversible after a few hours.”

Revisiting the definition of death

So much so that the medical definition of death may need to be updated, says Benjamin Curtis, an ethicist at Nottingham Trent University in the UK. “Given this study, many processes that we thought were irreversible will not be,” he told AFP. “And, according to the current medical definition of death, a person may not be truly dead for several hours,” with some processes continuing for a time after bodily functions have ceased.

This discovery may also spark debate about the ethics of such procedures. Moreover, almost all pigs during the experiment made powerful movements of the head and neck, according to one of the authors of the study, Stephen Latham. “It was quite unexpected for the people in the room,” he told reporters. The origin of these movements remains unknown, but he assured that electrical activity was never recorded in the brains of animals, which ruled out the restoration of consciousness.

These head movements, however, are “a major problem,” said Benjamin Curtis, because recent neuroscience research has shown that “conscious experience can continue even when the electrical activity in the brain cannot be measured. Therefore, it is possible that this technique caused suffering to people.” pigs and that it would cause suffering to people if used on them.”

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