Ssome aspects of death are not completely irreversible. On Monday, scientists from Yale announced that they successfully restored circulation and cellular activity in the brains of pigs four hours after the death of animals. Restored brains, as the band emphasizes, were not alive – but they did done they become cell-active.
The experiment depends on the newly developed system called BrainEx. In the edition Nature The team is going to publish Thursday. He explains that BrainEx relies on the connection of the cerebral vascular system with the solution developed to preserve brain tissue. The solution acts as a blood substitute and contains an oxygen-based carrier based on hemoglobin and a number of pharmacological agents to keep the dead or dying brain alive.
Scientists were ready to intervene with anesthetics. "
In the experiments, the team took 32 brains from the US Department of Agriculture slaughterhouse and connected them to the BrainEx system four hours after killing the pigs and removing their brains. The team did not observe any electrical activity related to perception, consciousness or consciousness – it was never the purpose of the study – but they witnessed another kind of miraculous result: restored BrainEx and sustained circulation to the main arteries, small blood vessels and capillaries.
In addition, the system reduced cell death, retained anatomical architecture, stimulated spontaneous neural activity and active brain metabolism. Meanwhile, the untreated control brains were spreading quickly.
The team stopped the experiment after six hours because of the limited availability of the BrainEx solution – which means they still do not know how long these functions could be maintained.
Not an attempt to restore consciousness
The aim of the study was not to restore consciousness, and the research was conducted in accordance with strict ethical guidelines: they did not want the brains to become conscious, a co-author and a bioethic Stephen Latham, Ph.D. said Wednesday, but they were ready to deal with this scenario if it happened.
'The researchers were ready to intervene using anesthetic and temperature-lowering means to stop organized global electrical activity if it were to appear,' says Latham. "Everyone agreed in advance that experiments related to renewed global operations can not go forward without clear ethical standards and institutional supervision mechanisms."
The results of this study clearly contrast with what we know about dead brains. The established idea is that after the oxygen and blood flow stops, the basic cellular functions stop within a few seconds and at this moment the nervous activity is irretrievably lost. Hence, the brain is expected to start the trajectory towards death and cell disintegration.
New research disturbs the thought that the collapse of a dead brain is fast and concrete. The team hopes that in the near future these studies could lead to a new way of examining the post-mortem brain, enabling researchers to study complex cellular and peripheral conditions after losing the life of the sample.
In a more hypothetical future, the BrainEx system can help in rescuing brain function in stroke patients, although it is currently unclear whether this approach would have the same effect on human tissues.
What is a dead brain?
It is clear that these discoveries open the future difficult to navigate. In the accompanying commentary, ethical scholars, including Duke Professor of Law and Philosophy Nita Farahana, Ph.D. write that the study "undermines long-term assumptions about what makes an animal – or a human – live". Now that scientists are capable, Farahana and her co-authors argue that new research guidelines for brain rebuilding are needed. What is considered to be a living brain – or dead – requires a better definition.
In another commentary, bioethicists Dr Stuart Youngner and Dr. Insoo Hyun argue that this study can "exacerbate tensions between efforts to save lives of individuals and try to get organs to give to others". they say they seem more and more reasonable, and we may have to revise our definition of a legally dead brain.
It is a distant scenario, but it is increasingly clear that our idea of what the brain is capable of – and how scientists can manipulate it – is changing. For now, life can not be restored after death – but the definition of death is now a question that is on the table.
Brains of humans and other mammals are very susceptible to disruptions in blood flow and lowering oxygen levels. We describe here the restoration and maintenance of microcirculation as well as the molecular and cellular functions of an intact porcine brain under normothermic conditions ex vivo up to four hours after death. We have developed an extracorporeal pulse-perfusion system, hemoglobin perfusate, cell-free, anti-coagulant, echogenic and cytoprotective, which supports hypoxia regeneration, reduces reperfusion injury, prevents edema and metabolically supports brain energy demand. Thanks to this system, we observed the behavior of cytoarchitecture; weakening of cell death; and restoration of vascular responses and inflammatory glial spontaneous synaptic activity and active brain metabolism in the absence of global electrocorticographic activity. These findings show that, under appropriate conditions, the isolated, intact large mammalian brain has underestimated the ability to restore microcirculation and molecular and cellular activity after a long time after death.