When a human or animal dies, the brain goes as well, and there is no turning back. A recent experiment, however, shows how dead pig brains are able to restore some function hours after death.
A group of scientists from Yale University were able to observe how circulation and cellular activity were restored in dead pig brains four hours after death. The findings challenge long-known understandings about timing and the irreversible nature of brains' cessation of function after death.
"The intact brain of a large mammal retains a previously underappreciated capacity for restoration of circulation and certain molecular and cellular activities multiple hours after circulatory arrest," says Nenad Sestan, senior author and professor of neuroscience, comparative medicine, genetics, and psychiatry.
A Twist To Established Understandings
Science considers the brain to lose signs of consciousness and electrical activity seconds after the brain lose oxygen and blood supply. Energy stores are also lost minutes after. The cells die, and it cannot be reversed. Molecular impairments then activate widespread degeneration of the brain.
The game changed for the Sestan's lab researchers when they observed that some small tissue samples that were harvested a couple of hours earlier demonstrated some signs of cellular life.
The scientists obtained dead pigs from a meatpacking factory, and put it in a specially formulated chemical solution.
Intrigued by their observations, the researchers retrieved processed pigs for food production to see the extent of postmortem brain viability. After four hours, they connected the vasculature of the brain to disseminate the solution they formulated to preserve brain tissue via a system called BrainEx. Indeed, some of the brain functions were restored after the experiment.
The system can help researchers perform specific techniques to study the structure and function of a large and intact mammalian brain. The inability to do so prevents scientists from thoroughly delving into topics such as root causes of brain disorders.
Stefano G. Daniele, study co-first author explains that in the past, scientists are only able to investigate large mammalian brain under a two-dimensional approach and use small tissue samples outside of their natural environment. Now, they are able to study the brain in three dimensions, which amps up their ability to study complex processes of cells and connectivity issues.
Not A Living Brain, Though
While the study looks very promising, the team emphasizes that the brains involved in the study did not have detectable electrical signals linked to normal brain function.
Zvonimir Vrselja, co-first author and associate research scientist in neuroscience, iterates that they did not observe any type of organized electrical activity associated with perception, consciousness, or awareness. Clinically, what they have is not a living brain but rather a cellularly active brain.
Application For The Future
At this point, the researchers have not yet identified any applications in the clinical setting. They believe, however, that their study can aid medical professionals to one day salvage brain function in stroke patients or examine the effectiveness of treatments targeted on cellular recovery after injury.
Ethical Considerations
Right now, the scientists don't think that the chemical solution they used can be applied to human brain study. Such solution lacks important contents such as certain blood cells and immune system components, which does not make it very suitable for normal living conditions.
If one day their study is to be applied for human tissue investigations, the scientists stress that it must be done under utmost ethical consideration.
Stephen Latham, director of Yale's Interdisciplinary Center for Bioethics, says regaining consciousness was never their goal. He adds that the team was prepared to take action with anesthetics and temperature-reduction to halt organized global electrical activity in case it occurs. The team members all agree that if any revived global activity emerges, they will stop, unless clear ethical standards and institutional mechanisms are in place.
The study was published in the journal Nature.
