What does resuscitation mean for the brains of dead pigs

In a study that raises complex questions about the demarcation line between life and death, a group of researchers reinstated some of the brain activity in the brain of slaughtered pigs.

The brains did not regain functioning suggesting that they were aware: there was no sign of coordinated movement of electrical signals, necessary for higher functions such as perception and perception. ;intelligence.

However, as part of an experimental treatment, the blood vessels in the brains of pigs began to work with the flow of a blood substitute and some brain cells regained their metabolic activity and even reacted to drugs. When the researchers performed tests with cuts of the brain tissue treated, they discovered electrical activity in some neurons.

The work, published in the journal Nature on April 17, is very preliminary and has no immediate impact on the treatment of brain lesions in humans. However, the idea that some parts of the brain may be able to recover after death, according to the conventional definition, contradicts all that is believed in the medical sciences about this organ and raises metaphysical puzzles.

"We had clear lines between" This is alive "and" This is dead ", said Nita A. Farahany, bioethics specialist and law professor at the University. Duke. "How do we now explain this intermediate category of" partially alive "? We did not think it could exist."

For decades, doctors and family members in mourning have wondered if the duties of a person suffering a serious brain injury following a stroke or heart attack could be restored. These brains really do not have salvation?

The new research shows that we know little about the injured brain and so-called brain death.

"It's impressive," said Jonathan Moreno, a specialist in bioethics at the University of Pennsylvania. "If ever there was a subject that deserved a great public deliberation on the ethics of science and medicine, that's it."

Until now, it has been badumed that the brain disintegrates rapidly when its blood supply is exhausted. The cells deteriorate and the connections between neurons collapse. Scientists felt that these changes were irreversible unless the blood was quickly restored.

Researchers at Yale University acquired the heads of 32 pigs that were slaughtered to sell their meat. The scientists opened the skulls and removed the brains. When the experiment began, the brain had not had blood circulation for four hours and was at room temperature at that time.

The team has developed a system called BrainEx, which injects an experimental solution into the intact brain. Scientists hope that the technology will help pave the way for new treatments for stroke, traumatic brain injury and diseases such as Alzheimer's disease.

The scientists injected the solution into the brains of the pigs for six hours. It carried oxygen in the tissues and contained chemicals that allowed scientists to track the flow by means of ultrasound.

The solution also contained chemicals to block the nerve signals. Scientists have speculated that brain cells could be better preserved and that their metabolism could restart more easily if the cells were not active.

However, the researchers did not want to risk the brain becoming aware, as implausible as it may seem. In case the team would have seen an electrical activity suggesting a state of consciousness, she planned to administer anesthetics to the brain and cool them immediately to stop the process.

In addition to the brains to which they applied the BrainEx solution, the scientists also badyzed the brains that had not received infusions and the others who received infusions of a placebo substance. None of the brains in these groups showed signs of activity and their cells deteriorated:

"This is not a living brain, but a brain with cellular activity," said Nenad Sestan, a neurologist at Yale University and head of research, about the tissue that has been reactivated.

"We wanted to test whether certain cell functions of a dead and intact brain could be restored."

Some people who looked dead after prolonged exposure to the cold were resuscitated and their brains continued to function, said Sestan. There were also patients who, after having suffered a stroke, spent up to sixteen hours with a clot blocking blood flow in certain parts of the brain, but regained their brain function as soon as the doctors had removed the clots.

Christine Grady, head of bioethics at the National Institutes of Health's (NIH) clinical center in the United States, who supported the research, said the work "allows researchers to map cells and connections between them." an impossible way before. "

The technique, he added, could then broaden the scope of studies on brain damage and cell repair, as well as the effects of drugs on the brain.

The ethical issues raised by research on reactivated brain tissue are virtually unprecedented. These include questions about the welfare of laboratory animals.

How will the ethicists decide if the goal justifies the suffering possibly caused by the investigation of a "partially alive" brain?

Farahany and other experts said that although there is no electrical activity in the brain, it might be possible to restore it. It is unclear what would have happened if his solution had not contained nerve inhibitors.

The work could also have implications for organ donation.

Stuart Youngner, bioethics specialist and co-author of a feature article that accompanied the study, gave an example.

In France and Spain, when a person has a heart attack that absorbs blood in the brain, emergency medical service personnel try to revive the heart for about half an hour.

In case of failure, rescuers preserve the organs by means of a portable cardiopulmonary device that pumps blood throughout the body. They also insert a balloon catheter to prevent the blood pump from reaching the brain; in this way, the person can be an organ donor because the brain is considered dead.

However, Younger asked, "If something like BrainEx was available, why not opt ​​for that rather than trying to give your organs?"

According to researchers, it will still be years before preliminary tests of brain resuscitation can be performed in humans. But Farahany pointed out that he foresaw a day when he would act of a standard medical practice.

"Maybe we'll see this in our life," he said.

* Copyright: c.2019 New York Times Press Service