The system could offer a boon to brain researchers by providing a way to study the brain as a whole instead of relying on isolated cells or tissue slices. Clinically, what they have is not a living brain but rather a cellularly active brain. Researchers at Yale University in New Haven, Connecticut, hooked the organs to a system that pumped in a blood substitute. Not A Living Brain, Though While the study looks very promising, the team emphasizes that the brains involved in the study did not have detectable electrical signals linked to normal brain function.
In a Nature commentary, bioethicists Stuart Youngner and Insoo Hyun of the Case Western Reserve School of Medicine in Cleveland said if such work leads to better methods for resuscitating the brain in people, it could complicate decisions about when to remove organs for transplant.
Stephen R. Latham, a bioethicist at Yale, asked how ethicists could determine whether the possible suffering the research could cause to a "partly alive" brain could be justified. "The intact brain of a large mammal retains a previously underappreciated capacity for restoration of circulation and certain molecular and cellular activities multiple hours after circulatory arrest", says Nenad Sestan, senior author and professor of neuroscience, comparative medicine, genetics, and psychiatry. Four hours after death, the researchers began pumping a warm preservative solution into the brain's veins and arteries. Fundamentally they were still dead brains.
"At no point did we observe the kind of organized electrical activity associated with perception, awareness, or consciousness", says co-first author Zvonimir Vrselja, associate research scientist in neuroscience.
The research grew out of efforts to enhance the study of brain development, disorders and evolution.
Cellular death within the brain is usually considered to be an irreversible process.
According to Sestan, when studying the cells in a lab dish "the problem is, once you do that, you are losing the 3D organization of the brain". They found the system preserved neural cell integrity, and restored certain neuronal, glial, and vascular cell functionality.
Researchers are now seeing if they can keep the brain functions they observed going for longer than six hours of treatment, which Latham said would be necessary to use the technology as a research tool.
Gauging awareness in a brain outside a body would probably be hard, given that the organ's surroundings would differ so radically from its natural environment.
While the advance has no immediate clinical application, the new research platform may one day be able to help doctors find ways to help salvage brain function in stroke patients, or test the efficacy of novel therapies targeting cellular recovery after injury, the authors say.
The latest study also raises questions about whether brain damage and death are permanent. The Experiment provides the evidence that the survival ability of the brain is significantly higher than previously assumed.
That could have practical and ethical consequences for organ donation.
They also found that blood vessels in treated brains responded to a drug that makes vessels widen.
In the meantime, scientists and governments are left to confront the legal and ethical quandaries related to the possibility of creating a conscious brain without a body.