Scientists have reactivated brain cell functions of dead pigs

PARIS (AFP) .- A group of investigators has succeeded in restoring certain neuronal functions in the brain of dead pigs for several hours, a step worthy of science fiction, which in no way proves that resurrection is possible.

The study published Wednesday in the magazine
Nature In fact, this indicates that in the brains studied, "no electrical activity that would imply a phenomenon of consciousness or perception" has been detected.

"These are not living brains, but brains whose cells are active," says one of the authors of the study, Nenad Sestan. According to this researcher from Yale University, these works show that "we have underestimated the cell's ability to restore the brain".

In addition, they suggest that the deterioration of neurons as a result of "stopping blood flow could be a long-term process," according to a statement from
Nature.

The mammalian brain is very sensitive to the decrease of oxygen provided by the blood. Therefore, when the flow is interrupted, the brain stops being oxygenated and the damage is irreparable.

The researchers used 32 brains of dead pigs for four hours. Thanks to a pump system called BrainEx, they were irrigated for six hours with a solution at a temperature equivalent to that of the body (37 degrees).

This solution, a blood substitute, has been designed to oxygenate tissues and protect them from degradation resulting from stopping blood flow.

The results were overwhelming: decreased destruction of brain cells, preservation of circulatory functions and even restoration of synaptic activity (electrical or chemical signals in the contact zone between neurons).

According to the researchers, the study could help to better understand the brain by studying how it degrades "post mortem". It would also pave the way for future techniques to preserve the brain after a heart attack, for example.

Theoretically, in the long run, it could be used to resuscitate a dead brain, something impossible at the moment.

Dead or alive?

"The immediate results posed by these findings are essentially ethical," says Professor David Menon, of the University of Cambrigde, who did not participate in the study.

Reopen the question on "what makes an animal or a man alive," say other scientists in a commentary published in parallel
Nature

"This study used pig brains that did not receive oxygen, glucose, or other nutrients for 4 hours, opening up previously unimaginable possibilities," says Nita Farahany, Henry. Greely and Charles Giattino, respectively professor of philosophy and neuroscientist. .

The study could highlight two scientific principles, according to these experts.

"First, the fact that neuronal activity and consciousness are definitely stopped after several seconds or minutes of interruption of blood flow in the mammalian brain."

"Secondly, the fact that if the blood circulation is not restored quickly, an irreversible process is activated and leads to cell death, then to that of the organ," they explain.

These three experts urge the establishment of "guidelines on the scientific and ethical issues raised by this study".

In another commentary published by
Nature, Bioethics experts point out that the development of the BrainEx technique could be detrimental to long-term organ donation.

For a transplant, most organs are taken from dead brain donors. If we consider that this state is reversible, what will happen to the gift?

The trio Farahany, Greely and Giattino quote a phrase from the American movie "The Promised Princess" of 1987: "There is a small difference between being almost dead and completely dead (…) Almost dead, it's still a not very alive, "says a healer in the film.