The implications of this research could redefine the boundary between life and death.
About five years ago, Yale School of Medicine neuroscientist Zvonimir Vrselja, Ph.D., and his colleagues shocked the medical community with a groundbreaking experiment. They removed a slaughterhouse pig's brain from its head and deprived it of oxygen at room temperature for four hours. Then, they hooked it up to their resuscitation machine and revived it -- to an extent.
A living brain's vasculature, or network of blood vessels, carries oxygenated, nutrient-rich blood to the brain through arteries and capillaries. So, the researchers used their machine, called BrainEx, to pump a mixture of preserving agents and drugs into the dead pig brain, targeting pathways typically damaged due to a loss of oxygen. The blend contained a substitute for blood made up of molecules that balance cell pH levels, drugs that prevent an excessive immune response, and antibiotics.
Several remarkable things happened: the gray cortex blushed pink. Brain cells resumed the production of proteins. Neurons began displaying signs of metabolic activity just as living cells do. The brain was once again carrying out basic cellular functions, but it wasn't conscious -- researchers didn't expect anything that extreme -- and couldn't be called "alive."
Still, the researchers watching this process said that the brain no longer appeared dead.
This result "goes against everything we thought we knew about death," Dr. Lance Becker, an expert in resuscitation, cardiac arrest, and critical care, told New Scientist in November. "We're at a real paradigm-shifting moment as we redefine what is life and what is death," continued Becker, who is also a researcher at the Feinstein Institutes for Medical Research in New York.
After testing it on pigs, Vrselja and his colleagues are now studying donated human brains with their machine, BrainEx. It's a more delicate operation than the pig experiments, and poses grave ethical consequences. For the porcine version of the experiment, researchers made sure that no perception-related brain activity occurred. They included sedatives in their formula that prevented electrical activity and ended the experiment after six hours, according to their 2019 paper published in Nature. "We had to develop new methods to make sure no electrical activity is occurring in an organised way that might reflect any kind of consciousness," Vrselja told New Scientist.
When dealing with a human brain, preventing perception would require even more care. If a person's brain inched toward consciousness under such an experiment, the consequences would be thorny, according to Hank Greely, a biomedical legal expert at Stanford University in California. "That's very tricky ethically, legally and scientifically," he told New Scientist.
Vrselja told the publication that he and his colleagues "have no intention of plugging anyone at the point of death into their BrainEx machine." But what they've accomplished so far is a significant step toward proving that brain death may not be as final as we once thought, arousing fresh hope that patients who are hovering between life and death can still be saved.
In the meantime, the researchers have had some success in keeping brains "cellularly active for up to 24 hours" so they can test treatments for neurological conditions. They hope to help patients with diseases such as Alzheimer's and Parkinson's.