美国国家公共电台 NPR Scientists Restore Some Function In The Brains Of Dead Pigs（在线收听）

AUDIE CORNISH, HOST:

Now we turn to a startling development in the world of science. The brains of dead pigs have been partially revived in the lab hours after the animals were killed in a slaughterhouse. NPR's Nell Greenfieldboyce reports that scientists and ethicists alike are grappling with the implications.

NELL GREENFIELDBOYCE, BYLINE: Brains are supersensitive to a lack of oxygen, and it's long been thought that oxygen starvation quickly leads to irreversible cell death. But some clues suggested the story isn't this simple.

Nenad Sestan is a neuroscientist at Yale University.

NENAD SESTAN: You can harvest cells from post-mortem brain hours after death and, basically, you can be carbon viable cells. You can study them.

GREENFIELDBOYCE: By keeping them alive in a lab dish.

SESTAN: The problem was that once you do that, you are losing the 3D organization of the brain.

GREENFIELDBOYCE: That limits what you can study about brains and brain injury. So he and some colleagues at Yale spent the last six years developing a new approach.

Stefano Daniele says they went to a local pork processing plant. They bought pig heads and immediately began their process.

STEFANO DANIELE: We've come up with a brain-flushing procedure to not only clear the residual blood that remains within the brain but also to cool the brain down.

GREENFIELDBOYCE: Back at the lab, the researchers took the brains and put them in a special chamber. They hooked up key blood vessels to a device that pumped in a chemical cocktail. This solution brought in oxygen, nutrients and various injury-repairing ingredients about four hours after the pigs were killed.

DANIELE: This really was a shot-in-the-dark project, and we had no preconceived notion of whether or not this could work.

GREENFIELDBOYCE: Well, it did. In the journal Nature, they say six hours of being hooked up to the device reduced cell death, prevented tissue degradation and restored some cellular functions. But - and this is important - they saw no signs of the kind of organized electrical activity that's associated with consciousness.

Stephen Latham is a Yale bioethicist who worked with the team.

STEPHEN LATHAM: It was never a goal of the research to try to restore consciousness to the pig brain. In fact, it was something that the researchers were actively worried about.

GREENFIELDBOYCE: He says the scientists monitored electrical activity and would've administered anesthesia if they saw any hint of consciousness.

What's more, the solution pumped into the brains contained a drug that inhibits brain cell activity. But if this drug was removed, could signs of consciousness emerge? And how would that kind of research even be regulated?

LATHAM: No one has ever thought about how to deal with this question of what if we induced consciousness in a brain that's not connected to any living animal? So nobody has jurisdiction over that.

GREENFIELDBOYCE: For example, animal welfare regulations didn't apply to this study in part because the pigs were used as food and in part because they were dead.

NITA FARAHANY: It's a dead animal. It's not subject to any research protections because you wouldn't expect that it would suffer from any pain or distress or, you know, need to be thought about in terms of humane care.

GREENFIELDBOYCE: Nita Farahany studies the ethics of new technologies at Duke University. She serves on a neuroethics group convened by the National Institutes of Health, which funded this work.

FARAHANY: My initial reaction was pretty shocked. You know, it's a ground-breaking discovery.

GREENFIELDBOYCE: She says it challenges our existing beliefs about what's alive and what's dead. And while this experiment produced no signs of the brain activity associated with consciousness...

FARAHANY: The potential is there. And we have to answer the questions of whether and, if so, how much of other kinds of activity can be restored to the brain and what that means.

GREENFIELDBOYCE: She says we still need to figure out the ethical path forward for this new way of keeping brains going in the lab.

Nell Greenfieldboyce, NPR News.

(SOUNDBITE OF ELEANOR FRIEDBERGER'S "HE DIDN'T MENTION HIS MOTHER")