Top boffins in the States believe that they may be on the track of a way to place living human beings into suspended animation, allowing them to survive long periods effectively frozen before being "reanimated" with no ill effects.

Dr Mark Roth, based at a Seattle cancer laboratory, got interested in suspended animation after looking at several cases where this has occurred spontaneously in humans.

One well-known case is that of Canadian toddler Erica Nordby, who wandered outside in the winter of 2001 wearing only her nappy. In the bitter cold her heart stopped beating for two hours and her body temperature plunged to just 16°C* before she was rescued, warmed - and came miraculously back to life, despite having literally frozen to death.

In another case a Japanese man, Mitsutaka Uchikoshi, fell asleep on a snowy mountainside in 2006. He was found 23 days later with a core body temperature of just 22°C*. He too was successfully reanimated having suffered no appreciable ill effects.

"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," says Dr Roth.

Roth and his colleagues wondered how it is that some people can enter a state of frozen suspended animation and then recover from it safely, whereas in general such a change of body temperature is deadly.

The scientists now think they may be on the track of an answer, having learned how to perform the same trick reliably with other lifeforms; in this case yeasts and nematode worms.

Yeasts and worms, like humans, will normally simply die if they are chilled down past a certain point. But Roth and his colleagues have found that if the little creatures are starved of oxygen before turning on the cold, they will go into suspended animation from which they recover on warming and go on to live normal yeasty or wormy lives.

Here's an illustrative vid from the team:

"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," says Roth. "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."

The idea here is not so much to place people into deep freeze in order to endure lengthy interstellar voyages, a staple idea in science fiction but unlikely in the near future (humanity is struggling even to assemble a Mars mission right now).

Rather, Roth and his colleagues think that their work might lead to techniques that would let paramedics or doctors "buy time" for severely injured or ill patients by putting them into suspended states like those achieved by Nordby and Uchikoshi. Then, once the underlying problem had been fixed, they could be reanimated.

Full details of the research are published online ahead of print in the journal Molecular Biology of the Cell, here (subscription link). ®

*Normal adult core body temperature is 37°C, a trifle lower for kids. Any variation of much more than a degree is cause for serious concern; several degrees' sustained variation is a probably fatal medical emergency of one kind or another.