Pig Brain Cells Brought Back From the Dead by Scientists

Scientists have revived the brain cells of dead pigs in a study that experts say calls into question our understanding of what makes an animal alive.

However, the authors of the research stressed they did not restore the brain function or consciousness of the animals, but said their work could one day pave the way for treatments of brain damage.

The brains of mammals can suffer irreversible damage within seconds if blood flow and oxygen is cut off, the authors of the study published in the journal Nature explained. But the authors at Yale hypothesized that cell death could be prevented, slowed and reversed hours after blood flow stopped.

To test their theory, they created a device called BrainEx: a machine that sits outside the organ and pumps a blood-like fluid of their own creation into the brain at body temperature. The team gained access to 32 brains from 6- to 8-month-old pigs, which were the byproduct of USDA-regulated food processing. They had died four hours prior to being connected to BrainEx.

After pumping the brains with the liquid for six hours, the scientists noticed the activity of some molecules, cells and synapses were restored. Cell death also appeared to slow. The effects lasted for up to 10 hours after the pigs died.

The authors argued the evidence suggests that, with the right interventions, the mammalian brain could withstand the loss of oxygen and blood supply better than previously thought.

But without testing the brains for longer, it remained unclear whether the equipment could restore electrical activity in the brain needed for it to become conscious or function.

"At no point did we observe the kind of organized global electrical activity associated with awareness, perception, or other higher-order brain functions," the authors wrote.

In fact, study co-author Stephen R. Latham, director of Yale's Interdisciplinary Center for Bioethics, explained in a press briefing that the team worked hard to ensure the brains did not regain consciousness due to ethical problems this would raise.

The authors of a comment piece published in Nature who were not involved in the study described the work as "remarkable."

"Although it is a long way off, researchers might one day consider using a system similar to BrainEx to treat humans for brain damage caused by a lack of oxygen," wrote Nita A. Farahany, a professor of law and philosophy at Duke University; Henry T. Greely, a professor of law at Stanford University and Charles M. Giattino, a Ph.D. researcher in the department of psychology and neuroscience and the Center for Cognitive Neuroscience at Duke University.

"Until now, neuroscientists and physicians have assumed that the cell death caused by this is irreversible. Treatment generally involves working with a person's remaining healthy brain tissue to help rehabilitate mobility, motor and other skills," they wrote. "Most fundamentally, in our view, it throws into question long-standing assumptions about what makes an animal, or a human, alive."

The technique could also make it easier to study the brains of mammals, they said.

Dominic Wilkinson, professor of medical ethics at the University of Oxford, said in a statement: "This research reminds us that 'death' is less an event, and more of a process that occurs over time. Cells within the human organism may be alive for some period of time after the human person has died."

This new approach could lay the groundwork for studies using human brains donated to science after death and that could provide insight into "some of the microscopic structure and functions of the brain," said Wilkinson.

Stuart Youngner, a professor of bioethics and psychiatry, and Insoo Hyun, a professor of bioethics and philosophy, both at Case Western Reserve University School of Medicine, wrote in a separate commentary that such advances in brain resuscitation technology rekindle the debate around when medics should stop attempting to save a life and try to take organs for donation for another person's benefit.

David Menon, a professor and the head of the division of anesthesia at the University of Cambridge, described the paper as of high quality. But he suggested scientists are a long way from seeing this technique used in a clinical setting.

Menon highlighted that the results were observed in isolated brains: "An important fact, since restoration of blood flow to the rest of the body (following a cardiac arrest, for instance), may activate injury processes in non-brain tissues which produce substances that damage the brain (for example, through activation of inflammation)."

"It is also worth pointing out that testing for brain death is usually undertaken after far longer intervals after the insult than the four hour time point in these experiments—often more than a day later," he said.

Wilkinson cautioned: "At present we should be clear that this research does not have any implications for brain death or for organ transplantation. Nor does it mean that there is a realistic prospect, any time soon, of bringing back people from the dead.

"'Brain death' refers to the irreversible loss of the capacity for awareness and consciousness. Once someone has been diagnosed as 'brain dead' there is currently no way for that person to ever recover. The human person that they were, has gone forever."