Researchers in the US say they have managed to keep the brains of decapitated pigs alive outside of the body for up to 36 hours by circulating an oxygen-rich fluid through the organs.
While the scientists, led by Yale University neuroscientist Nenad Sestan, say the brains are not conscious, they add the feat might help researchers to probe how the brain works, and aid studies into experimental treatments for diseases ranging from cancer to dementia.
The revelation, disclosed in the MIT Technology Review and based on comments Sestan made at a meeting at the US National Institutes of Health in March, has received a mixed reaction in the scientific community.
Anna Devor, a neuroscientist at the University of California, San Diego, told the MIT Technology Review the feat could help researchers probe the connections between brain cells, allowing them to build a “brain atlas”.
However others were quick to stress that the development did not mean humans could expect to cheat death any time soon, noting that it is not possible to transplant a brain into a new body.
“That animal brain is not aware of anything, I am very confident of that,” Sestan is reported to have told the NIH meeting. But he noted that ethical considerations abound: “Hypothetically, somebody takes this technology, makes it better, and restores someone’s [brain] activity. That is restoring a human being. If that person has memory, I would be freaking out completely.”
Frances Edwards, professor of neurodegeneration at University College London, told the Guardian the development could prove useful to researchers. “It could be useful for studying connections between cells and at some level working out the network interactions in a large brain,” she said. “There would be some advantages for imaging and certainly for developing imaging techniques.”
But Edwards said the research was unlikely to be replicated in humans, and dismissed the idea that body transplants were on the cards.
“It would be a major, pretty much impossible step even to get this far with a human brain,” she said. “Both in the pig and in a human, the whole brain is only available at death, but in the pig, you are taking a healthy animal and able to control exactly when and how it dies and immediately take out the brain. It would need to be cooled within a few minutes and then only rewarmed when oxygenated.”
That, she said, is unlikely to be possible for humans, noting that even in the case of humans who had been pronounced brain-dead, “by the time the brain is accessible it would be well and truly compromised”.
The upshot, said Edwards, is that while the development is useful for experiments, it is unlikely to be applied to humans. “All of that is a fairy tale,” she said.
Sestan and his colleagues are reported to have used more than 100 pigs, whose brains were recovered from slaughterhouses. The researchers then used a sophisticated system called BrainEx to keep the cells alive, circulating an oxygenated fluid through the organ.
It is not the first time an animal’s brain has been kept alive outside of the body: the feat has previously been achieved in guinea pigs, while Edwards noted that the brainstems and hearts of rodents including mice have also been kept in working order outside of the body.
“Part of the reason why the cortex is removed in these preparations is because of the potential ethical implications,” said Edwards. “Even the use of brain slices is equivalent at some level keeping a part of the brain alive isolated for a day or so.”
But, she added, the new development was an achievement.
“The impressive part is that they can apparently effectively [keep oxygen getting to] such a large brain intact,” she said.