Suspending Life: The Science of Cryonics

Vitrification is a scientifically sound process - Storey uses it in his own research on freeze-tolerant animals. But he doesn’t agree that the process can be used successfully to preserve people and then have them come back to their original state. “You can vitrify a single human cell and have it come back. You can even vitrify sheets of human cells, so long as they are only one or two cells thick, and have them come back. But you can’t vitrify a huge human organ; they are too big, they are too complicated, and you cannot change their temperature fast enough,” says Storey.

The Alcor Life Extension Foundation and the Cryonics Institute disagree. The Alcor website states: “Vitrification can happen on any scale at any cooling rate if enough water is replaced by cryoprotectant.” Prior to 2001, Alcor used glycerol to prevent ice formation but like most cryoprotectants, it is quite toxic at room temperature. They are now using a mixture of two different cryoprotectants which is less potent.

The big thaw

Credit: www.carleton.ca/~kbstorey

The wood frog enters a deep, frozen state of hibernation to survive the cold winters.

Even if an entire organ is successfully vitrified, thawing it out is likely to cause damage due to recrystallization. “Tiny ice crystals that form around 0 degrees C get bigger and bigger and bigger,” says Storey. He studies animals like the wood frog that live in very cold climates and reach a deep, frozen state of hibernation to survive the winter. The liver of these animals makes glucose, a cryoprotectant, which is circulated to cells so that ice doesn’t form inside them. Subsequently, their blood circulation ceases, their hearts stop and they have no detectable brain activity for weeks, but when it’s time to thaw out, they regain all their vital functions within hours. But these animals have several adaptations to deal with freezing temperatures that humans just don’t have. They can turn on various genes that make special proteins to help cells deal with the stress of freezing and thawing. “To genetically engineer all those mechanisms would be an infinitely difficult problem,” says Storey.