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Scientists have restored activity in the brain of pigs slaughtered hours earlier, suggesting hope for medical progress and questions about the definition of death.
The researchers pointed out that brains could not think or feel anything. According to medical standards, "it's not a living brain," said Nenad Sestan of the Yale School of Medicine, one of the researchers reporting the findings Wednesday in the newspaper. Nature.
But the work revealed a surprising degree of cell resilience in a brain that has lost its blood and oxygen supply, he said.
"Cell death in the brain occurs in a longer time than expected," said Sestan.
Such research could lead to new therapies for stroke and other ailments, and would provide a new way to study the brain and understand how drugs work within it, researchers said. They said that they had no current intention to try their technique on the human brain.
The study was funded primarily by the National Institutes of Health.
How cells work
The 32 brains came from pigs killed to feed in a local abattoir. Scientists put the brain in an apparatus of their laboratory. Four hours after the animals died, scientists began to inject a specially designed blood substitute through the organs.
Brains did not show any large-scale electrical activity that would indicate awareness. The study was not intended to restore consciousness, but rather to investigate whether particular functions could be restored long after death.
After six hours of pumping, scientists discovered that individual brain cells in an area of the brain had retained key details of their structure, while untreated brain cells had severely degraded.
When the scientists removed these neurons from the treated brains and stimulated them electrically, the cells reacted to indicate their viability.
And by studying the artificial blood before it enters the treated brains and after its appearance, the researchers found evidence that brain cells absorbed blood glucose, oxygen, and produced carbon dioxide, which which meant that they worked.
They also found that the blood vessels in the treated brains responded to a drug that expanded the vessels.
Surprising results
Sestan said the researchers did not know if they could restore normal brain function if they chose this goal. If such an awareness had appeared in the reported experiments, scientists would have used anesthesia and low temperatures to smother and stop the experiment, said study co-author Stephen Latham of Yale.
There is no good ethical consensus on such research if the brain is conscious, he said.
Researchers now see that they can maintain the observed brain function for more than six hours of treatment, which, according to Latham, would be needed to use technology as a research tool.
Christof Koch, president of the Allen Institute for Brain Science in Seattle, who did not participate in the study, said he was surprised at the results, especially since ## 147 ## 39, they were obtained from a large animal.
"This type of technology could help us increase our knowledge to bring people back to the land of the living" after a drug overdose or other catastrophic event that deprived the brain of oxygen for an hour or two, a- he declared.
Unlike experiments on pigs, such treatment would not involve removal of the brain from the body.
Ethical minefield
Pork work is also in an ethical minefield, he said. On the one hand, this relates to the widely used definition of death as the irreversible loss of brain function, because irreversibility "depends on the state of the technology, and, as shown this study, it is constantly progressing, "he said.
And someone might try this with a human brain someday, he said. If future experiments restore electrical activity on a large scale, would this indicate a consciousness? Does the brain "experience confusion, delusion, pain or agony?" He asked.
It would be unacceptable even in an animal brain, he said.
In one Nature Bioethicists Stuart Youngner and Insoo Hyun, of the Cleveland Case Western Reserve School of Medicine, said that if this work could improve brain resuscitation methods, decisions about transplanting organs to transplant could be complicated.
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