Pig brains back to life after death

Image credits SCIENCE PHOTO LIBRARY Copyright:© UCL, GRANT MUSEUM OF ZOOLOGY/SCIENCE SOURCE

In a feat sure to fire up ethical and philosophical debate, a new system has restored circulation and oxygen flow to a dead mammal brain.

The brain, presumably, can not live much without blood. Within seconds, oxygen supply is cut off, electrical activity disappears, and consciousness is lost. If the flow of blood flow does not resume, within minutes, neuronal death begins, steadily, and without compensation, and eventually the declared line of death.

Or maybe not? When a team of scientists led by Nenad Sestan at the Yale School of Medicine, this process may occur over a much longer time frame, and may not be inevitable or reversible as believed.

The team obtained 32 pigs from the altar and placed them in oval vessels. They were immersed in nutrient and preservative chemicals, using heart rate pumps. This system, called BrainEx, maintains the structure of the brain in total, preventing its dissolution. Blood vessels in the blood vessels, which have become sensitive again to vasodilators and arteries, have also resumed. While stopping many nerves and other cells of the dead, and recovered their ability to consume sugar and oxygen. Even some of these saving nerves began to glow. "It was all a surprise," says Zvonimir Vrselja, who conducted most of the experiments alongside Stefano Daniele.

There have long been indications that it is not necessary that an oxygen outburst kills nerve cells as quickly as it was assumed. However, Jimo Borjigin of the University of Michigan says that when she began studying brain activity in dying mice, "my colleagues told me that once there was no oxygen, all the cells would die within minutes." And that the Sestan team has shown that cells have been coherent not for minutes, but for a few hours later. This type of studies is long overdue. "

The brains in jaundice is a popular and alarming science fiction series, but in those stories, the brains are alive, aware, and self-aware. The other in the Sestan experiments zero in all three things. Although some neurons may be directed individually, there are no signs of coordinated brain-level electrical activity that indicates reception, sensation, consciousness or even life. The team remained prepared with painkillers if any of these nuggets were achieved - none of which occurred. "The pigs were brain dead when these brains reached the gate and at the end of the experiment, they remained brain dead," said Stephen Latham, a Yale University ethicist who advised the team.

"I do not see anything in this report detracting from the belief that brain death is specific to death," says Winston Chiong, a neuroscientist at the University of California.
The question of when to announce the death of a person has become more controversial since doctors began to rely heavily on nerve signals, beginning about 1968 when the standard of "brain death" was defined. But this diagnosis depends on the widespread loss of brain activity - a line that, at least until now, is still irreversible and can not be reversed.

This is a diagram showing the various parts of the BrainEx device. It’s complicated! 

Nature

After MIT Technology Review had been working with Sestan for a year, it began to receive e-mails from people asking if it could restore the brain function to their loved ones. This can not be very likely. BrainEx is not a re-life room.

"This will not lead to human brain transplants," adds Karen Rommelfanger, who heads the Neuroscience Science Program at the University of Amroy. "I do not think this means that the individual (the point before it is not as after) is coming, I pray in life is more capable than before. "

Why do we study this? Says L. Syd M Johnson, a neuroscience scientist at Michigan Technological University. BrainEx may not be able to fully revive brains that have died for hours, but Yama Akbari, a neurologist at the University of California's intensive care unit, wonders if it would be more successful if it was applied within minutes after death. On the other hand, this help can keep the oxygen-starving brain cells alive and coherent with patients still waiting for treatment. "This is an important institution study," says Akbair.

These applications are too far away, and may not even materialize at all. "This is an extraordinary opening," says Nita Farahany, a biomedical ethics scientist at Duke University. Although neuroscientists can study neuronal cells grown in labs, or on thin slices of brain tissue, neither of these can depict anything from the three-dimensional entanglement that makes the brain hot. By restoring some activity to the brains of dead pigs, the Sestan team created something similar to the real thing. Paradoxically, it is certainly "the better the likeness, the sharper the moral dilemmas," Farahay says.

On the right, you can see brain cells preserved by the BrainEx apparatus, 10 hours after death. On the left, an untreated brain 10 hours after death. The neurons are stained in green. “Ten hours postmortem, neurons and astrocytes undergo cellular disintegration unless salvaged by the BrainEx system,” the researchers find.

 Nature

Johnson adds that no animals were made for the study: the team got brains from pigs killed for eating. "In the meantime, there are millions of animals killed every year, and this is a rich source available to brain-test without further damage," she says.

The study needs to be reproduced by independent teams. Before anyone goes any further in technology, or even thinking about human probabilities, there are several ethical issues to consider.
For example, is the team really sure that these brain-like brains have no awareness? Latham, a scholar of ethics at Yale University, trusts this. He says that even people under anesthesia show signs of a wide coordinated electrical activity in the brain, so the absence of these signs strongly suggests that "we do not even have the potential to develop consciousness."
But awareness is still difficult to define, as well as measured. There was absolutely no one who measured him in a brain without a body. How can you measure perception, pain, or suffering "in a brain that has returned its circulatory function and nerve function, but is still disconnected from the external sense?" Asks Steven Hyman, a neuroscientist at the Broad Institute of Harvard and MIT. "This is a scientific problem and a very difficult policy issue," says Johnson. "I think very much that it is not likely that consciousness or mind will be restored in a brain that has died for several hours, but I am very sure that even if it is, we will not know."

It is also unclear as the brains of pigs have never prepared coordinated activity. Is this because the team waited for four hours? Was it because they had brainwashed for six hours? Or because they added neurotransmitter chemicals to the fluid they pumped into the brain? (Since they did so because excessive glow helps kill nerve cells in oxygen-starving brains). If this is the case, can isolated minds gain awareness if they are lifted?

It is possible, and certainly this is the identification of the limit between life and death. But that experience is definitely not among the choices. The next and only step of the team is to try BrainEx for a longer period of time.
If this leads to signs of coordinated activity, "we will have to close the search for a while," Latham says, "because there is no institutional entity we can consult. Current legislation in animal experiments excludes both those that have been raised for food, or died. There is nothing to cover that gray area, which is formed by brain isolation, with signs of cell activity and the possibility of consciousness.

This depicts a problem I wrote about last year: achievements in neuroscience - from preserving dead tissue to cultivating blocks of brain tissue in agar - precede the ethical frameworks that help us think about this research. The Sestan team "realizes that they have been in line with their line and have done everything in their power to seek guidance more than many researchers did," says Farahany. "But the truth is that there is no guide."

Brains were thought to degrade almost immediately after death.DENIS BALIBOUSE / REUTERS

In the comments accompanying a new study, others have proposed several immediate guidelines. Do not interrupt the neural activity blockers until we know what to do. Do not do similar studies without painkillers. Initial research is in ways of identifying neural signals that may be indicative of a mind or consciousness. Transparency. With the adoption of these principles, organizations such as the National Institutes of Health or the National Academies of Sciences, Engineering, and Medicine should host groups of scientists and citizens to discuss the ethics and limitations of this research and draw clear guidelines.

Farahany says: "First we need to know how to do this violently in the animals." If it is finally possible to revive a dead brain to the point of consciousness, "What comes and does not come with this? Are memories interrelated? Are there self-identifying identities? How can we answer these questions if we can not ask an animal? "


What would change if the researchers moved from the isolated brains to the brains still in their owners' skulls? Or human experiences. Could this increase the already significant shortage of cultivable organs if the point at which the medical intervention becomes obsolete? These are all questions for the distant future, but they deserve to be answered before the future becomes present.

SourceNature
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