Challenging the notion of death itself, researchers have successfully restored the cellular activity, blood vessel architecture and circulatory function of pig brains removed from the body, reanimating the organs four hours after death.
It's generally believed that once blood flow to the brain is restricted, its network of tiny vessels become clogged and cellular death is rapid. But researchers at Yale University, led by Nenad Sestan, took the brains of dead pigs from a meat packing plant and pumped a special, proprietary solution through the porcine grey matter. Connecting the brain to the solution four hours after death protected them from natural processes that would cause it to rapidly degrade and restored some, but not all, activity.
The study, published in the journal Nature on April 17, describes the team's preservation solution, dubbed BrainEx, which was able to preserve the structure of their test ungulates thinking box up to 10 hours after death -- opening up a new way to study brain function. The researchers note that while the structure and cellular activity of the brain was protected, this did not bring the pigs back from the dead.
"At no point did we observe the kind of organized electrical activity associated with perception, awareness, or consciousness," said Zvonimir Vrselja, a co-author on the paper, in a statement.
"Clinically defined, this is not a living brain, but it is a cellularly active brain."
BrainEx is described as a "pulsatile perfusion system", which means it intermittently pumps the researcher's special solution through the brains vast architecture of blood vessels. The solution itself is made up of an acellular, hemoglobin-based formula that does not coagulate, which is warmed to normal body temperature.
The team compared the brains of dead pigs connected to the BrainEx system with those that did not receive the treatment, demonstrating the potential for the solution to restore the structure of small blood vessels, activate metabolism and reduce cell death.
If your own brain immediately jumps to whether or not this would be possible in humans, there are a few caveats. First, the specially formulated solution -- the "artificial blood" -- that the team used does not contain the same makeup found in human blood. It also poses big ethical questions and forces us to reconsider the definitions of death.
A year ago, MIT Technology Review discussed Sestan's work with BrainEx and the idea of the "brain in a bucket". Such an advance in technology may enable scientists to pump the BrainEx solution through postmortem human samples to study diseases and treatments that would otherwise be impossible to investigate in a living human. But the idea of re-animating the brain in a bucket outside the body asks questions of consciousness and feeling.
If the technology advanced enough -- and if there was electrical activity -- would that be considered "thought" or "consciousness"? Or do we need to be connected to sensory organs for such sensation?
Those questions will likely remain unanswered as the way forward, for now, focuses on applications such as stroke therapy or understanding how drug treatments might affect the way brains are wired.
"The new technology opens up opportunities to examine complex cell and circuit connections and functions that are lost when specimens are preserved in other ways," said Andrea Beckel-Mitchener, a team lead of the BRAIN Initiative which funded the research, in a statement. "It also could stimulate research to develop interventions that promote brain recovery after loss of brain blood flow, such as during a heart attack."
Originally posted April 17, 11 a.m. PT
Updated April 17, 2:40 p.m. PT: Adds additional information, adds Nature paper.