Scientists have renewed some activity within the brains that had been slaughtered several hours ago, increasing hopes for some medical advances and questions about the definition of death.
The mobs could not think or feel anything, the researchers point out. According to medical standards, "this is not a living brain," said Nenad Šestan of the Yale University Medical School, one of the researchers who published the results in the journal. Nature.
However, work has revealed a surprising degree of resistance between cells within the brain that has lost blood and oxygen supply, he said.
"The brain cell death occurs over a longer period of time than we previously thought," Sestan said.
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Such research could lead to new therapies for stroke and other conditions as well as to a new way of studying the brain and the way drugs work in it, researchers say. They said they did not have immediate plans to try their technique on the human brain.
The study is mainly funded by the National Institute of Health.
32 brain came from pigs killed for food in a local slaughterhouse. Scientists have put the brain in the apparatus in their lab. Four hours after the animals died, scientists began pumping a specially designed blood substitute through the organs.
The moves did not show great electrical activity that would point to consciousness. Restore awareness was not the goal of the study, which was to investigate whether certain functions could be renewed long after death.
After six hours of pumping, scientists found that single brain cells retained the key details of their structure in one part of the brain, while the cells from the untreated brain were seriously degraded. When scientists removed these neurons from the treated brain and stimulated them electrically, the cells reacted in a way that showed sustainability. By studying artificial blood before entering the treated brain and after they appeared, researchers found evidence that brain cells absorb sugar and oxygen in the blood and produce carbon dioxide, signal to function.
They also found that the blood vessels in the treated brain reacted to a drug that caused the spread of blood vessels.
Sestan said the researchers did not know if they could renew the normal brain function if they chose this goal. If such awareness emerged in reported experiments, scientists would use anesthesia and low temperatures to suppress and stop the experiment, said study co-author Stephen Latham of Yale. There is no good ethical consensus on such a research if the brain is conscious, he said.
Researchers now see if they can keep the brain functions that have been watching for more than six hours of treatment, which Latham said would require technology to be used as a research tool.
Christof Koch, chairman of Allen's Seattle Science Research Institute, who did not participate in the study, said he was surprised by the results, especially in the big animal.
"This kind of technology could help us increase our knowledge to bring people back to the ground of life" after overdose of drugs or other catastrophic events that the oxygen brain dropped an hour or two, he said. Unlike experiments in pigs, any such treatment would not involve brain removal from the body.
The job of the pig also enters the ethical minefield, he said. First, it touches on the widely-used definition of death as a non-returning brain function, because irreversibility "depends on the state of technology, and as this study demonstrates, it is constantly evolving," he said.
And someone could try it with human brain one day, he said. If future experiments would return a great electrical activity, would that mean consciousness? Will the brain "experience confusion, misconception, pain, or agony?" he asked. That would be unacceptable even in the animal brain, he said.
IN Nature commentators, bioethics Stuart Youngner and Insoo Hyun of the Case Western Reserve School of Medicine in Cleveland said that if such work leads to better methods for brain revitalization in humans, it could complicate decisions on when to remove transplant organs.