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.

Pigs are commonly used as a models for transplant research. A new project looks to maintain their brains after death. Carsten Koall | Getty

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.

Brain in a bucket

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?

The “brain in a jar” scene from the 1983 comedy The Man with Two Brains. Though fodder for jokes, as brain-preservation technology advances medical ethicists are taking it seriously. Streamline | "The Man With Two Brains" (1983)

Also, because federal safety regulations apply to people, not “dead” tissues, it is uncertain whether the US Food and Drug Administration would have any say over whether scientists could attempt such a reanimation procedure.

“There are going to be a lot of weird questions even if it isn’t a brain in a box,” said an advisor to the NIH who didn’t wish to speak on the record. “I think a lot of people are going to start going to slaughterhouses to get heads and figure it out.”

Sestan said he was concerned about how the technology would be received by the public and by his peers. “People are fascinated. We have to be careful how fascinated,” he said.

Comatose state

It’s well known that a comatose brain can be kept alive for at least decades. That is the case with brain-dead people whose families elect to keep them attached to ventilating machines.

Less well explored are artificial means of maintaining a brain wholly separated from its body. There have been previous attempts, including a 1993 report involving rodents, but Sestan’s team is the first to achieve it with a large mammal, without using cold temperatures, and with such promising results.