Researchers are keeping pig brains alive outside the body

If it were tried on a person, it might mean awakening in the ultimate sensory deprivation chamber.

In a step that could change the definition of death, researchers have restored circulation to the brains of decapitated pigs and kept the reanimated organs alive for as long as 36 hours.

The feat offers scientists a new way to study intact brains in the lab in stunning detail. But it also inaugurates a bizarre new possibility in life extension, should human brains ever be kept on life support outside the body.

The work was described on March 28 at a meeting held at the National Institutes of Health to investigate ethical issues arising as US neuroscience centers explore the limits of brain science.

During the event, Yale University neuroscientist Nenad Sestan disclosed that a team he leads had experimented on between 100 and 200 pig brains obtained from a slaughterhouse, restoring their circulation using a system of pumps, heaters, and bags of artificial blood warmed to body temperature.

There was no evidence that the disembodied pig brains regained consciousness. However, in what Sestan termed a “mind-boggling” and “unexpected” result, billions of individual cells in the brains were found to be healthy and capable of normal activity.

Reached by telephone yesterday, Sestan declined to elaborate, saying he had submitted the results for publication in a scholarly journal and had not intended for his remarks to become public.

Since last spring, however, a widening circle of scientists and bioethicists have been buzzing about the Yale research, which involves a breakthrough in restoring micro-circulation—the flow of oxygen to small blood vessels, including those deep in the brain.

“These brains may be damaged, but if the cells are alive, it’s a living organ,” says Steve Hyman, director of psychiatric research at the Broad Institute in Cambridge, Massachusetts, who was among those briefed on the work. “It’s at the extreme of technical know-how, but not that different from preserving a kidney.”

Hyman says the similarity to techniques for preserving organs like hearts or lungs for transplant could cause some to mistakenly view the technology as a way to avoid death. “It may come to the point that instead of people saying ‘Freeze my brain,’ they say ‘Hook me up and find me a body,’” says Hyman.

Such hopes are misplaced, at least for now. Transplanting a brain into a new body “is not remotely possible,” according to Hyman.

The Yale system, called BrainEx, involves connecting a brain to a closed loop of tubes and reservoirs that circulate a red perfusion fluid, which is able to carry oxygen to the brain stem, the cerebellar artery, and areas deep in the center of the brain.

“I think a lot of people are going to start going to slaughterhouses to get heads and figure it out.”

In his presentation to the NIH officials and ethics experts, Sestan said the technique was likely to work in any species, including primates. “This is probably not unique to pigs,” he said

The Yale researchers, who began work on the technique about four years ago and are seeking NIH funding for it, acted out of a desire to construct a comprehensive atlas of connections between human brain cells.

Some of these connections probably span large regions of the brain and would thus be traced more easily in a complete, intact organ.

Sestan acknowledged that surgeons at Yale had already asked him if the brain-preserving technology could have medical uses. Disembodied human brains, he said, could become guinea pigs for testing exotic cancer cures and speculative Alzheimer’s treatments too dangerous to try on the living.

The setup, jokingly dubbed the “brain in a bucket,” would quickly raise serious ethical and legal questions if it were tried on a human.

For instance, if a person’s brain were reanimated outside the body, would that person awake in what would amount to the ultimate sensory deprivation chamber, without ears, eyes, or a way to communicate? Would someone retain memories, an identity, or legal rights? Could researchers ethically dissect or dispose of such a brain?