Ethicists advise caution with research that blurs the line between life and death.
Three-week-old pigs in Walcott, Iowa. (Daniel Acker/Bloomberg News)
The brain is fragile, and if deprived of oxygen —
for example from a massive heart attack, or through drowning — it will
quickly and catastrophically degrade, leading to irreversible brain
death. And that’s it — the end.
But that medical orthodoxy now must contend with a major report
published Wednesday in the journal Nature that is simultaneously
fascinating and disturbing: Researchers at Yale School of Medicine say
they have restored some cellular function in pig brains from animals
decapitated four hours earlier at a local slaughterhouse.
Over
the course of a six-hour treatment, the brains were infused with a
cocktail of synthetic fluids designed to halt cellular degeneration and
restore cellular functions, such as metabolic activity. It worked: The
brains continued to consume oxygen and glucose. Many brain cells,
including neurons, which send messages within the brain and to the rest
of the body, ceased decaying and appear to have been revived in dramatic
and detectable ways.
The scientists detected “spontaneous synaptic
activity,” which means the neurons were capable of sending out signals,
and the cells responded to external electrical stimulation. Cells
removed from the treated brains and examined under a microscope had
regained the shape of living cells, noted lead author Zvonimir Vrselja, a
Yale neuroscientist.
The pig brains remained,
by any traditional definition, dead. The researchers detected no signs
of consciousness or any other “global” mental activity. But the study
suggests that brain cells are hardier than previously thought, said
study co-author and Yale neuroscientist Nenad Sestan.
“The
death of a cell, or in this case, organ, is a gradual, stepwise
process,” Sestan said. He stressed that the revivifying system the
researchers developed, which they dubbed BrainEx, may not reverse
cell death and restore brains to what would be considered a stable,
living state. It’s possible, he said, that “we are just postponing the
inevitable.”
The researchers are mindful that this
is controversial territory with great potential to stoke outrage or,
simply, the heebie-jeebies. Such a head-snapping experiment inevitably
generates nightmarish scenarios involving live brains in vats, brain
transplants, the Zombie Apocalypse, and other mad-scientist story lines
(brilliantly crafted, somehow, by neurons firing away inside the skulls
of conventionally living human beings).
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