L345 大脑复生

Yale Researchers Build BrainEx Machine to Restore Brain Function After Death

Researchers at Yale University spent six years building a machine, which they call BrainEx, that can restore functionality in brain cells of recently slaughtered pigs. However, the Yale University research team is careful to say that none of the brains regained the kind of organized electrical activity associated with consciousness or awareness. However, the experiment showed that a small amount of cellular function was either restored or at least preserved.

The implications of this study have surprised ethicists, as they imagine how this research should move forward and how it fits into the current understanding of what separates the living from the dead. "It was mind-blowing," says Nita Farahany, who studies the ethics of emerging technologies at Duke Law School. "My initial reaction was pretty shocked. It's a groundbreaking discovery, but it also really fundamentally changes a lot of what the existing beliefs are in neuroscience about the irreversible loss of brain function once there is deprivation of oxygen to the brain."

The brain is extremely sensitive to a lack of oxygen and shuts down quickly. But researchers have long known that viable cells can be removed from post-mortem brains hours after death, says Nenad Sestan, a neuroscientist at the Yale School of Medicine in New Haven, Connecticut. Such cells can be studied in a lab dish, Sestan says, "but the problem is, once you do that, you are losing the 3D organization of the brain." He and some colleagues wondered whether it might be possible to study brain cells while leaving them in an intact organ. Doing so meant somehow supplying them with oxygen, nutrients and various other cell-protective chemicals.

The scientists then spent six years developing a technique to do that, testing their methods on nearly 300 pig heads which they acquired from a local pork processing center. "This really was a shot-in-the-dark project," says team member Stefano Daniele. "We had no preconceived notion of whether or not this could work."

The research team removed the brains from the pigs' heads and placed the isolated brains in an experimental chamber. The researchers attached key blood vessels to a device that pumped in a specially formulated chemical mixture for six hours, starting about four hours after the pigs had been killed. These brains looked considerably different from pig brains that were left alone to deteriorate. "We found that tissue and cellular structure is preserved and cell death is reduced. In addition, some molecular and cellular functions were restored," Sestan says. "This is not a living brain, but it is a cellularly active brain."

However, according to another commentary written by Case Western Reserve University bioethicists Stuart Youngner and Insoo Hyun, research like this could complicate the effort to secure organs for transplant from people who have been declared brain-dead. If people who are declared brain-dead could become candidates for attempts at brain resuscitation, they write, "it could become harder for physicians or family members to be convinced that further medical intervention is futile."