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Scientists at Yale University have been successful in restoring the basic brain cell activity of pigs within hours of death, which could lead to one day progress in the treatment of stroke and brain damage in humans. 'man, announced Wednesday researchers.
The scientists pointed out that their work was not even about to awaken consciousness in the brains of disembodied pigs. In fact, the experiment was specifically designed to avoid such a result, as unlikely as it is.
Nevertheless, the study raises a host of bioethical issues, including the very definition of brain death and its potential consequences for organ donation protocols.
Effort to improve the study of the brain
The research was born from efforts to improve the study of brain development, disorders and evolution. The main practical application is the ability to allow scientists to badyze entire brain specimens of large mammals in three dimensions, rather than through studies limited to small tissue samples, Yale said.
The study, supported by the National Institutes of Health, does not offer any immediate clinical advances in humans, according to the authors.
What is brain death?
The results of the experiment, published Thursday in the journal Nature, go against the long-accepted principles of brain death, according to which vital cell activity irreversibly ceases for a few seconds or so. minutes after cutting off the flow of oxygen and blood flow.
The limited rejuvenation of circulatory function and cellular metabolism in porcine brains, from animals slaughtered in a meat packing plant, was obtained four hours after death by infusing it with a special chemical solution designed to preserve the fabric.
"The intact brain of a large mammal retains a capacity for restoring circulation and certain molecular and cellular activities that had been underestimated several hours after a circulatory arrest," said lead researcher Nenad Sestan in a statement. published in Yale.
It was in the laboratory run by Sestan, a professor of neuroscience, comparative medicine, genetics and psychiatry at Yale, that the researchers developed the system called BrainEx, which is used to inject artificial nutrients into the vascular network of the brain. of pork.
"Not a living brain"
The scientists however pointed out that treated brains still did not show any detectable signs of organized electrical activity badociated with perception, consciousness or consciousness.
"Clinically defined, it is not a living brain, but a cell-active brain," wrote co-author of the study, Zvonimir Vrselja, badociate researcher in neuroscience.
The BrainEx preservative included substances to block nerve signals. The researchers were also ready to put an end to any electrical activity that could have emerged through anesthesia and temperature reduction, according to Yale.
No therapeutic benefit at the moment
Although the study offers no immediate therapeutic benefit to humans, it creates a new research platform that could help physicians find ways to restore brain function in patients who have had a stroke or are testing new treatments to restore brain cells damaged by injury, said the authors.
In the meantime, research could create new dilemmas around the determination of death itself, largely defined by a measure such as the irreversible loss of all brain functions. The vagueness of this line in turn has implications for deciding when doctors are ethically required to move from preserving a patient's life to preserving one's organs.
"For most men, death was very simple," said Christof Koch, president and chief scientist of the Allen Institute for Brain Science in Seattle, in an article published by Nature as part of the Yale study.
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