CNN  — 

A new experiment has raised medical and ethical questions as serious as those surrounding human gene editing: A support system delivering artificial blood to pig brains prevented degradation of important neural functions, Yale researchers discovered.

Dr. Nenad Sestan, senior author of the new study and a professor of neuroscience, noted that blood flow and some energy use could be seen in the dead brains, but the neural circuits showed no higher-level function, including the global electrical activity needed for awareness.

Still, this new experimental system, called BrainEx (for ex vivo, or outside the body), may have “broader applications” – some relevant to humans, Sestan and his co-authors wrote: “This possibility raises important ethical considerations that must be addressed.”

“Could BrainEx ever be used with human brains? Is it possible in the future that more brain function could be restored?” wondered Christine Grady, chief of the Department of Bioethics at the National Institutes of Health Clinical Center. She added that these “logical questions” are not answered by the study, though it “raises them for consideration now and in the future as the science progresses.”

The research, which was funded by the National Institutes of Health’s BRAIN Initiative, was published Tuesday in the journal Nature.

Sophisticated artificial blood-pumping system

How can researchers study brain dynamics when, within minutes of death, the loss of blood flow causes irreversible damage in the brains of humans and other advanced mammals? To overcome this obstacle, Sestan and his colleagues created a system designed to lessen various processes of tissue degradation in postmortem brains.