Anoxia-induced suspended animation helps survive hypothermia

January 26, 2016

Roth first got the idea to study the link between anoxia-induced suspended animation and hypothermia from documented cases in which humans have managed to make complete recoveries after apparently freezing to death. Widely publicized cases include Canadian toddler Erica Nordby, who in the winter of 2001 wandered outside clad only in a diaper. Her heart had stopped beating for two hours and her body temperature had plummeted to 61 degrees Fahreneit before she was discovered, rewarmed and resuscitated. Another incident that made headlines was that of a Japanese man, Mitsutaka Uchikoshi, who in 2006 fell asleep on a snowy mountain and was found by rescuers 23 days later with a core body temperature of 71 degrees Fahrenheit. He, too, was resuscitated and made a full recovery.

"There are many examples in the scientific literature of humans who appear frozen to death. They have no heartbeat and are clinically dead. But they can be reanimated. Similarly, the organisms in my lab can be put into a state of reversible suspended animation through oxygen deprivation and other means. They appear dead but are not. We wondered if what was happening with the organisms in my laboratory was also happening in people like the toddler and the Japanese mountain climber. Before they got cold did they somehow manage to decrease their oxygen consumption? Is that what protected them? Our work in nematodes and yeast suggests that this may be the case, and it may bring us a step closer to understanding what happens to people who appear to freeze to death but can be reanimated," Roth said.

The mechanism by which anoxia-induced suspended animation protects against extreme cold has to do with preventing the cascade of events that lead to biological instability and, ultimately, death. For example, suspended animation preserves the integrity of cell-cycle control by preventing an organism's cells from dividing in an error-prone fashion. During suspended animation, the cell cycle is reversibly halted. Upon reanimation, the cycle resumes as normal.

"When an organism is suspended its biological processes cannot do anything wrong," Roth said. "Under conditions of extreme cold, sometimes that is the correct thing to be doing; when you can't do it right, don't do it at all."

SOURCE Fred Hutchinson Cancer Research Center