In the past, the absence of a heartbeat allowed doctors to declare someone’s death – today, this happens through the irreversible loss of all circulatory functions (circulatory death) or all brain functions (brain death). Yale University scientists, however, knocked over a brick of what looked like a solidly constructed concept by restoring circulation and cellular activity to a pig’s brain four hours after his death.
“The main implication of this discovery is that cell death in the brain takes place over a longer period of time than we thought. Instead of happening over minutes after death, we show that it is a gradual process and, in some cases, can be postponed or even reversed, ”said neuroscientist Nenad Sestan, one of the authors of the study now published in the journal Nature.
The experiment (started in 2012, as reported by The New York Times) used the BrainEx system, a computerized network of pumps, heaters and filters that control the flow and temperature of a perfusate (liquid that passes through tissues slowly and continuously) specially created. The brains of 32 pigs were irrigated with the solution hours after the animals were killed in a commercial slaughterhouse.
Cell functions reactivated
After four hours, the researchers found that BrainEx had not only restored but maintained some living cells in the brain – many of the basic cellular functions were observed, contrary to the precept that an end to blood flow and, consequently, oxygen would lead to death of the brain in minutes.
Neural activity was not detected at any time. “Clinically defined, it was not a living brain, but an active cellular brain,” explained the neuroscientist Zvonimir Vrselja, co-author of the study.
Ethics between life and death
It is not yet possible to know if the procedure can be applied to people, since the perfusate produced does not have many of the components of human blood. It is also necessary to consider another element that accompanies research that involves the limits between life and death: ethics.
“The restoration of consciousness was never an objective of the researchers, who were prepared to intervene with the use of anesthetics and temperature reduction to interrupt organized electrical activity if it arose”, explained the director of the Yale Interdisciplinary Center for Bioethics and also the author of the study, specialist in medical law and ethics Stephen Latham.
According to him, “everyone agreed in advance that experiments involving revived brain activity could not proceed without clear ethical standards and mechanisms for institutional oversight.”