Yale University School of Medicine researchers have announced the partial revival of cellular function in pigs’ brains that have been declared dead several hours prior. The researchers created a system, known as BrainEx, which restores blood and oxygen flow into the dead pigs’ brains.
The system is roughly similar to existing dialysis machines, which filters blood and removes waste products and excess water in case of damaged, dysfunctional, or missing kidneys.
But unlike dialysis machines, the BrainEx system will likely be controversial for many reasons. Our definition of brain death will be shaken to the core, and the ensuing ethics debate can make or break BrainEx’s applications, especially in humans.
The researchers, however, welcome the ethics debates that will inevitably come with their announcement. The scientific community also appears to welcome the breakthrough – Nita Farahany, a Duke University School of Law bioethicist, considers it “an extraordinary and very promising breakthrough for neuroscience” – since it provides a better model for human brain studies.
The feat will also likely challenge many of the fundamental theories in neuroscience, such as the irreversible effect of loss of oxygen flow to the brain. The researchers have proven that said assumption isn’t true, and the legal and ethical issues that will inevitably follow won’t likely reverse it.
The BrainEx makers didn’t kills pigs and other animals for the experiment. Instead, they purchased pig heads from a food processing plant; the pigs have already been butchered for their meat. The pig brains technically remained dead since these showed no signs of consciousness or awareness, as evidenced by electrical neural activity.
Nenad Sestan, the study’s co-author and a neuroscientist, said that the pig brains aren’t living brains in the clinical definition.
According to researchers, the BrainEx system kept the pig brains in significantly better shape in comparison with brains naturally decomposing. The restored functions included taking in oxygen and glucose for up to six hours at a time, an achievement that can boost studies on human brains. In turn, the system can provide the foundation for studying brain diseases and disorders in a better manner.
The BrainEx system is comprised of computer-controlled filters and pumps that send a proprietary hemoglobin-based solution through the dead pig brains. The solution is injected in a manner that mimics the ebb and flow of the body’s natural circulation, as well as formulated so that it’s visible on ultrasound scans.
According to the researchers, Yale University has filed a patent for the BrainEx system on their behalf. But the system’s procedures and parts will be made free and available to academic researchers and non-profit organizations.
The researchers also ensured that the pig brains wouldn’t gain consciousness or awareness – or wake up – during the procedure. They were ready with appropriate measures including temperature reduction measures and anesthesia administration just in case. They also ensured that the solution contained compounds that block neural activity.
Stephen Latham, the study’s co-author and director of the Yale Interdisciplinary Center for Bioethics, said that, “It was in fact never a goal…of the research to have consciousness restored.”
Khara Ramos, the director of the Neuroethics Program at the National Institute of Neurological Disorders and Stroke, said that, “We’re really excited about this as a platform that could help us better understand how to treat people who have had heart attacks and have lost normal blood flow to the brain.”
How do scientists and doctors define death? Death is final although its definition has changed over time, particularly with the advent of modern medical technology that kept organs alive. These devices, such as mechanical ventilators, keep the heart and lungs functioning even as the brain cannot.
But while the heart and lungs can be kept functioning via mechanical means, the brain isn’t so easily kept alive. The brain is akin to a high-performance, complex machines with unique demands including a steady and stable supply of oxygen-rich blood for optimum performance.
Once blood flow is cut off to the brain, the affected individual loses consciousness within a few seconds. In just five minutes, the essential molecules including ATP and glucose in the brain run out and a death spiral begins.
Until the pioneering BrainEx system, scientists considered brain death as irreversible due to the combination of factors. The chemical processes of nerve cells are thrown out of whack, the blood in the brain becomes more acidic due to carbon dioxide buildup, and glutamate leaks become toxic. The brain’s blood vessels and smaller structures break down, too.
As researchers gained a deeper understanding of the brain and its processes, the definition of brain death also evolved. Today, the American Academy of Neurology uses a checklist for determining brain death in patients.
The BrainEx researchers have consulted many of the world’s leading ethicists and neuroscientists including the Neuroethics Working Group to ensure that the study won’t be so controversial. In time, the study’s results can be used for the betterment of mankind, hopefully.
