A controversial experiment with pigs has put the scientific community to ask what it means to be alive. Hours after the pigs had been slaughtered in a slaughterhouse, the scientists managed to restore some parts of their brain's cellular activity.
The result has been amazing. The hypothesis that brain cells suffer irreversible damage with death has been seriously questioned.
In the study published in the magazine Nature, it is noted that the brain of large mammals "retains a previously underestimated restorative capacity" for some activities and cellular circulation hours after death, said neurology professor Nenad Sestan of the Yale University School of Medicine, the main author of the study.
This means that the brain dies a long time after what was believed or that there is "a wider window of opportunity" to restore its cells, Sestan said during a press conference on Tuesday.
Therefore, this shows that brain death It is something that happens gradually. But the most important: it is something that in some cases can be postponed or reversedsaid Sestan.
The pigs, however, the researchers noted, were dead. His brain did not exhibit any type of activity or function proper to a normal brain with functions such as consciousness. "This is not a living brain"said Sestan. "But it's a cellularly active brain".
The work could provide scientists with new ways to study the brain, allowing them to examine functions in an intact brain in a way that previously would not have been possible. This, in turn, could help scientists better understand brain diseases or the effects of a brain injury, the researchers said.
Although the current study was conducted in pigs and not in humans, the brains of pigs are larger and more similar to humans, compared to the brains of rodents.
In the study, the researchers developed a novel system to study intact brains after death, called BrainEx. It is a network of pumps that channels a synthetic solution, a substitute for blood, into the arteries of the brain at a normal body temperature.
Using BrainEx, the researchers studied 32 brains of pigs post-mortem that were obtained from a pork processing plant (which would otherwise have been discarded). The brains were placed in the BrainEx system four hours after pig death and allowed to "perfuse" with the synthetic blood substitute for six hours.
During this time, the BrainEx system not only preserved the structure of brain cells and reduced cell death, but also restored some cellular activity. For example, some cells were metabolically active, which means they used glucose and oxygen and produced carbon dioxide.
Other cells reacted with an inflammatory response when stimulated with certain molecules.
In contrast, the "control" brains that were not treated with BrainEx decomposed rapidly.
"We can see dramatic differences between the brains we're dealing with our technology" and the brains that do not, Sestan said.
Dr. Neel Singhal, an assistant professor of neurology at the University of California, San Francisco, who was not involved in the study, said the work was "stimulating" because of some of the ethical issues raised.
For example, although scientists are far from being able to restore brain function in people with severe brain injuries, in the event that a certain type of restoration of brain activity were possible, "we would have to change our definition of brain death", Singhal told Live Science.
The researchers did not see any sign of conscience, nor was this an objective of the investigation. In fact, the synthetic blood solution included several chemicals that block neuronal activity, the kind of activity that would be needed for consciousness.
Moreover, if some kind of organized electrical activity had appeared, which was needed for consciousness, the researchers were prepared to take measures to stop that activity by using anesthesia and reducing brain temperature, said study co-author , Stephen Latham, director of Yale's Interdisciplinary Bioethics Center. In other words, finish the experiment if this happened.
In a commentary published along with the study, Nita Farahany, a professor of law and philosophy at Duke University, and her colleagues asked for more guidance on the ethical issues raised by the study, which say "puts into question the long-term assumptions about what makes an animal or a human being alive".
Such problems include how to detect awareness from the beginning and how long systems like BrainEx should be allowed to work.