Science fiction has blurred the line between life and death since Mary Shelley wrote Frankenstein over two centuries ago. Modern sci-fi and fantasy in television shows such as Altered Carbon, The Walking Dead, and Game of Thrones carry on that tradition. Shelley's work reflected the cutting-edge science of the day: inducing cadavers to move through electrical stimulation [See 1]. Recently, a study by Vrselja and colleagues [2] at the Yale School of Medicine showed that science continues to blur that line. These researchers preserved crucial elements of brain function in pig brains four hours after the pigs' deaths.

One persistent challenge for doctors and neuroscientists is that mammal brains that have lost their oxygen supply do not always react well when oxygen returns. Damage, called reperfusion injury, can occur. Typically, the brain is at risk for permanent damage after only a few minutes without oxygen. Even when patients do recover from oxygen deprivation, recovery may not be permanent. Weeks after recovery, their brain functions may still deteriorate. Clearly, bringing someone back isn't as simple as flicking an on/off switch. 

There are exceptions to this rule. If body temperature drops, for instance in someone who has fallen into icy water, they can sometimes recover after up to 6 hours. A recent review of these cases states in its title, “Nobody is dead until warm and dead.” This led researchers like Vrselja to look for other ways besides hypothermia to protect the brain during reperfusion. 

Vrselja and colleagues discovered a way to protect “warm and dead” brains, using a process called BrainEx [2]. BrainEx uses a computer-controlled pump to deliver a solution to the brain. This solution contained cytoprotective (cell-protecting) chemicals and energy sources. The researchers found that after six hours of the process, BrainEx brains did not show the signs of damage that typically would result from hypoxia. The brains did not show swelling or dry out. Support cells called glia functioned the way they were supposed to. Neurons in the hippocampus responded appropriately to signals. This last point is particularly important because the hippocampus helps the brain to learn and form memories.

Vrselja's team took pains to prevent the pig brains from achieving normal brain activity. Their aim was to keep the cells alive and restore normal circulation, not to revive the animals. This study cannot determine whether BrainEx could restore consciousness or awareness. Still, it raises the intriguing but troubling question: what happens if somebody else uses the same technology to push farther, resuscitating a human and allowing their patient to emerge from anesthesia?