Written by Gina Kolata
In a study that raises questions about the line between life and death, researchers have restored some cellular activity to brains removed from slaughtered pigs.
The brains did not regain anything resembling consciousness: There were no signs indicating coordinated electrical signaling, necessary for higher functions like awareness and intelligence.
But in an experimental treatment, blood vessels in the pigs’ brains began functioning, flowing with a blood substitute, and certain brain cells regained metabolic activity, even responding to drugs. When the researchers tested slices of treated brain tissue, they discovered electrical activity in some neurons.
The work is very preliminary and has no immediate implications for treatment of brain injuries in humans.
“We had clear lines between ‘this is alive’ and ‘this is dead,’ ” said Nita A. Farahany, a bioethicist and law professor at Duke University. “How do we now think about this middle category of ‘partly alive’? We didn’t think it could exist.”
The new research confirms how little we know about the injured brain and so-called brain death. Bioethicists like Farahany were stunned and intrigued by the findings, published Wednesday in the journal Nature.
Until now, it has been assumed that the brain declines quickly when its blood supply is cut off. Cells deteriorate, and the connections between neurons crumble. Scientists have believed those changes are irreversible unless blood is quickly restored.
Researchers at Yale University acquired the heads of 32 pigs killed for their meat. The scientists sawed into the skulls and removed the brains. By the time the experiment started, the brains had been without blood and at room temperature for four hours.
The team has developed a system called BrainEx that pumps an experimental solution into the intact brain. The scientists hope the technology will help point the way to new treatments for strokes, traumatic brain injuries and diseases like Alzheimer’s.
The scientists pumped the solution into the pigs’ brains for six hours. It brought oxygen to the tissue and contained chemicals that allowed the scientists to track its flow with ultrasound.
The solution also contained chemicals intended to block nerve signals.
In addition to the brains that got the BrainEx solution, the scientists also examined brains that did not receive infusions and those receiving infusions of a dummy substance. Brains in both groups showed no signs of activity, and their cells deteriorated.