Human Hibernation Now Is Possible

You've seen it in movies, read about it in comic books as a kid, heard about it since you were two when it comes to bears...and now scientists say humans can hibernate, too.

But wait: I thought humans could already hibernate. There's even a term for it: "attending high school."

SUSPENDED animation is poised to move from science fiction to reality: scientists have successfully induced a state of reversible hibernation in mammals for the first time, using methods that could eventually be applied to human beings.

The breakthrough in the United States promises to allow doctors to slow human metabolism almost to a standstill, protecting critically ill patients from damage to the brain and other organs that would normally be inflicted by oxygen deprivation. Patient trials could begin within five years.

The “hibernation on demand” technique, which has been pioneered in mice, also raises the prospect of putting astronauts to sleep for long voyages in space — a staple of science fiction films such as Alien and 2001: A Space Odyssey.

In a study at Fred Hutchinson Cancer Research Centre in Seattle, a team led by Mark Roth used hydrogen sulphide gas to place mice into artificial hibernation, slowing their cellular activity virtually to a standstill. The animals were left in this state for up to six hours before being revived without any lasting ill effects.

As hibernation drastically reduces the amount of oxygen that cells need to survive, such suspended animation would have significant medical benefits if it could be induced among human patients. It could be used to buy time when treating severe blood loss, hypothermia, fevers, heart attacks and strokes, in which oxygen deprivation kills off tissue, leading to disability or death.

MSNBC's Robert Roy Britt has some excellent points about where all of this can go — and what we've seen so far. A small taste:

Squirrels, bears, snakes and many other animals hibernate naturally, some more deeply than others. Humans have been known to hibernate by accident, Roth and his colleagues point out.

A Norwegian skier was rescued in 1999 after being submerged in icy water for more than an hour. She had no heartbeat and her body temperature was 57 degrees Fahrenheit (normal is 98.6). She recovered.

Canadian toddler Erika Nordby wandered outside at night and nearly froze to death in 2001. She wore only a diaper and T-shirt. It was minus 11 Fahrenheit (-24 Celsius). When found, her heart had stopped beating for two hours and her body temperature was 61 degrees F. She suffered severe frostbite but required no amputations and otherwise recovered.

"Understanding the connections between random instances of seemingly miraculous, unexplained survival in so-called clinically dead humans and our ability to induce — and reverse — metabolic quiescence in model organisms could have dramatic implications for medical care," Roth said. "In the end I suspect there will be clinical benefits, and it will change the way medicine is practiced, because we will, in short, be able to buy patients time."

* Medical treatment. A patient can be put in suspended animation until a cure is found. A patient could hibernate until an organ donor is found.

* Difficult political decisions. "Senator Frist, I'll let you know about my vote on the 'nuclear option' but my doctor says I have to hibernate until after the 2006 elections before I can give you an answer."

http://www.alertnet.org/thenews/newsdesk/N21709760.htm

WASHINGTON, April 21 (Reuters) - Mice forced to breathe hydrogen sulfide -- known best for its rotten egg smell -- go into a kind of suspended animation, U.S. researchers said on Thursday in a finding that may help save human lives.

Although hydrogen sulfide gas is toxic in high doses, it may activate some of the mechanisms that cause other animals to go into hibernation, they wrote in this week's issue of the journal Science.

Finding a safe way to do this in humans could lead to new ways to treat cancer and prevent injury or death from blood loss, or help people undergo and recover from surgery better, said the team at Fred Hutchinson Cancer Research Center.
"We are, in essence, temporarily converting mice from warm-blooded to cold-blooded creatures, which is exactly the same thing that happens naturally when mammals hibernate," said Mark Roth, who led the study, in a statement.

"We think this may be a latent ability that all mammals have -- potentially even humans -- and we're just harnessing it and turning it on and off, inducing a state of hibernation on demand," said Roth, a biochemist.
Bears do it, amphibians do it, and people occasionally hibernate, too. Many cases have been documented of small children, and the occasional adult, reviving from near-drownings in icy water after their body temperatures had dropped and they had stopped breathing for more than an hour.

"Understanding the connections between random instances of seemingly miraculous, unexplained survival in so-called clinically dead humans and our ability to induce and reverse metabolic quiescence in model organisms could have dramatic implications for medical care," Roth said.

"In the end I suspect there will be clinical benefits and it will change the way medicine is practiced, because we will, in short, be able to buy patients time."
In the mice, Roth's team tried doing it chemically with toxic hydrogen sulfide, a colorless gas made by the breakdown of sulfur compounds. In high doses it kills by stopping cell metabolism.

"When mice were exposed to 80 parts per million of hydrogen sulfide, their oxygen consumption dropped 50 percent and their carbon dioxide output dropped by 60 percent within the first five minutes," they wrote in their report.
"If left in this environment for six hours, their metabolic rate dropped by 90 percent."

Lowering metabolism reduces the need for oxygen. If this could be replicated in humans, it could help buy time for critically ill patients on organ-transplant lists and in operating rooms, emergency rooms and on battlefields, Roth said.
Cancer treatment might be improved, too, he said. If healthy tissue can be put into suspended animation, it might be possible to raise doses of radiation to kill tumor cells, Roth said.

"Right now in most forms of cancer treatment we're killing off the normal cells long before we're killing off the tumor cells. By inducing metabolic hibernation in healthy tissue we'd at least level the playing field," he said.

Hydrogen sulfide is toxic in high doses but the mice did not appear damaged in any way, Roth said.
"The cool thing about this gas we're using, hydrogen sulfide, is that it isn't something manufactured that we're taking down from a shelf -- it isn't 'better living through chemistry' -- it's simply an agent that all of us make in our bodies all the time to buffer our metabolic flexibility. It's what allows our core temperature to stay at 98.6 degrees, regardless of whether we're in Alaska or Tahiti," Roth said.

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