by Devin Juros
Edited by Felix Green
What happens to the brain when someone dies? The brains of mammals need oxygen and sugar to sustain the cells of the neurons within. They obtain these vital substances from blood flow, as there is a network of blood vessels that runs through the brain to deliver these substances to every neuron. Yet, when one dies, the heart stops pumping blood throughout the body, including the brain. Because of this, neurons no longer receive oxygen and sugar and they begin the process of death and degeneration. This process leads to several questions about the time frame and severity of neuron degeneration post-mortem. How quickly does this degenerative process take place in the brain after death? How long can the brain continue to function? Finally, is it possible to revive some brain activity or function post-mortem?
Z Vrselja and others recently investigated this last question using the brains of dead pigs aged six to eight months old at the time of death . A perfusion system was used to circulate various solutions through the blood vessels of the dead pig brains in an effort to revive activity in them several hours post-mortem. Four hours after death, the control group brains were perfused with control perfusate (mainly salts and some antibiotics), while the experimental group brains were perfused with BEx perfusate. The BEx perfusate included substances that promote metabolism, protect cells, and help the cells take up oxygen, along with antibiotics to protect against infection.
Compared to the control group, the BEx perfusate group’s brains showed significantly less apoptosis (programmed cell death), a less swollen brain shape, better preserved neuron shape, and more intact synapses, which are necessary for brain activity. Widespread brain metabolism also remained intact, meaning that the brain cells of this group were generally alive and functioning. However, brain activity under BEx perfusion occurred only spontaneously and in scattered areas: there was no coordinated activity across the brain.
“It’s alive!” we might think. “Pig Frankenstein has been brought back to life.” Certainly, this experiment showed that circulation and specific molecular and cellular functions in a pig’s brain can be restored after death with BEx perfusion technique. In other words, neurons in the brains of mammals can survive for longer after death if kept in the right environment. Yet, given the lack of organized widespread brain activity associated with higher-order brain functions like awareness or perception, true normal brain function was not actually restored. Fortunately, Pig Frankenstein cannot wreak as much havoc as Shelley’s, yet.
The groundbreaking results of this experiment have several clinical applications. For example, a solution similar to the BEx perfusate could be circulated through the brains of people who suffer traumas that reduce blood flow or oxygen transport to the brain, like a heart attack or respiratory failure. This treatment could potentially reduce or even prevent brain damage from these types of trauma, although, further research is needed to see if there are any unintentional side effects to this type of treatment. It is possible that some brain areas are detrimentally impacted by the perfusate or that one’s brain chemistry could be altered, potentially causing changes to memories, personality, mood, and more.
Just as important, however, are the ethical questions that arise from this type of research. First among these is, does the pig feel pain or suffering when activity in its brain is restored? This may seem like an insane question as the pig has already been dead for several hours and its body has been discarded. Yet, we know that pain can be perceived by the brain even without physical harm. Since they only showed sporadic activity, it is unlikely that the pig brains used in this experiment felt any intense pain or suffering. But, as this type of study continues, researchers must be cognizant that pain and suffering in a post-mortem brain is possible, at least in theory.
A possible application of this research, with numerous ethical questions, is head transplantation. Head transplantation has been investigated throughout history in various animal models, including mice, dogs, and monkeys, with limited success. The BEx perfusion technique could potentially resolve some of the challenges of head transplantation, like maintaining brain circulation during surgery and optimizing immunosuppression to prevent infection . Head transplantation may seem like science fiction but this controversial procedure may be possible in the foreseeable future, allowing patients who have suffered horrible organ damage or bodily trauma to continue to live in another body, perhaps of someone who died young of a brain tumor.
Another potential implication of this research is keeping human brains alive after death. If an extremely effective perfusate is developed, this could theoretically be accomplished. This application might not be very useful in older people whose neurons have already started to degenerate due to diseases related to old age; however, it might be desirable for children who die tragically young. Most parents would likely do anything for their children to be alive again. But is pumping the brain full of various antibiotics and other substances the answer to this question? Is a person still alive if only their brain is alive? What is the quality of life of such a brain? Would it feel pain and suffering or, perhaps, restlessness and boredom? Only the future will tell the direction of this research, and the applications that are pursued.
 Vrselja Z, Daniele SG, Silbereis J, Talpo F, Morozov YM, Sousa AMM, et al. Restoration of brain circulation and cellular functions hours post-mortem. Nature [Internet]. 2019 [Cited 2019 Nov 17]; 568, 336-343, doi:10.1038/s41586-019-1099-1
 Lamba N, Holsgrove D, Broekman ML. The history of brain transplantation: a review. NCBI [Internet]. 2016 [Cited 2019 Dec 1]; 158(12), 2239-2247, doi:10.1007/s00701-016-2984-0