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Researchers at the Yale School of Medicine restored the brain activity of dead pigs several hours earlier. The discovery could revolutionize the field of neuroscience and the way scientists think about the boundaries between life and death.
By circulating a cocktail of cell-regenerating compounds in pigs' brains, the researchers prevented tissue breakdown and restored some cellular functions. If reproduced, their technique could serve as a model for drug testing and will affect scientists' understanding of brain plasticity after traumatic events such as stroke.
But the researchers pointed out that they do not restore consciousness to the brain. Although the group observed activity in individual cells, the brain lackedrelated activity – a requirement of conscience.
"We wanted to study what happens in the brain after a global injury … and if we could restore certain cellular and molecular functions in the intact brain four hours after death," said News co-author Stefano Daniele GRD ' 21. "We managed to do it."
Daniele and co-lead author Zvonimir Vrselja, a neuroscience researcher, led the study under the supervision of the neuroscience professor at Nenad Sestan School of Medicine.
Vrselja and Daniel took several years of trial and error to perfect their research protocol. In the end, every successful test required a 10-hour sprint.
"We have an entire dance that we do," Daniele said.
Generally, scientists will purchase test animals from specialized research companies. But Vrselja and Daniel took a different approach: each iteration of the experiment began in a local food processing plant, where the duo would wait until a new specimen was available.
"We did not want to kill any animals for this research," Daniele explained. "So we just used a fabric that was going to becard. "
After securing the fabric, the two rushed to medical school and removed the pig's brain from his skull in four hours.
Vreslja and Daniele designed a systemm to pump and circulate their solution throughout the brain. For six hours, the instrument acted as an artificial circulatory system: it pushed the solution around the brain while eliminating waste from the tissues.
"A lot of these components are readily available and nobody really thought about assembling them in any particular way that could give rise to this type of study," Daniele said.
Miraculously, after treatment, the team was able to show repeatedly that brain cells could respond to stimuli. Drug treatment has enlarged the blood vessels of the brain. And individual neurons gave peaks of electrical activity.
In general, a brain deprived of oxygen and other nutrients for four hours is considered dead. But the activity described in the study shows that brain cells are more robust and able to survive longer than before.should.
However, for the moment, the clinical definitions of brain death are intact.
"I see nothing in this report that can undermine confidence in brain death as a criterion for death," said The Atlantic Winston Chiong, a neurologist at the University of California at San Francisco.
In 2016, when the team worried that their experience would cause the simultaneous triggering of brain neurons – the marker of consciousness – they recruited Stephen Latham, director of the Yale Interdisciplinary Center for Bioethics, who became co-author of the study.
In all studies involving human or animal subjects, federal law requires scientists to consult their institution's ethics committees before beginning research. Although this study has passed the bar, future studies may enter a gray area.
"A disembodied brain obtained from an already dead pig is not an animal or a human subject," explained Latham. "No one is able to ask questions such as" this brain suffering? Can he suffer if he sits alone in a tub without a connection to a body? Even if we see EEG [signal]does this indicate a conscience? Does this indicate a painful conscience? "
Following the publication of this historical study, Sestan, the lead author, asks the independent groups to replicate the results.
Other members of the medical community are in agreement. The head of the neurology department at Yale New Haven Hospital, David Hafler, who did not participate in the study, told the newspaper that the job was to be replicated as a "natural process of Science".
"Until the work is reproduced independently by another laboratory," he said, "in my mind, it does not exist."
However, Hafler said the results of Yale's study are "one of the most remarkable discoveries I've seen in my career".
"I really congratulate them for this document that really changes things," Hafler told the News. "They should be proud to be Yale."
On Wednesday evening, Nature reported that 132 media had resumed the study.
Marisa Peryer | [email protected]
Matt Kristoffersen | [email protected]
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