26 March 2008

Sleeping Through the Singularity

What are the prospects for human hibernation? When will human medicine be able to put techniques of suspended animation to good use for lifesaving and organ transplantation? Better yet, when will we see hibernation pods such as in the movie "2001". Recent research in mice at Mass General Hospital in Boston, may provide a few vague clues.
Low doses of the toxic gas responsible for the unpleasant odor of rotten eggs can safely and reversibly depress both metabolism and aspects of cardiovascular function in mice, producing a suspended-animation-like state. In the April 2008 issue of the journal Anesthesiology, Massachusetts General Hospital (MGH) reseachers report that effects seen in earlier studies of hydrogen sulfide do not depend on a reduction in body temperature and include a substantial decrease in heart rate without a drop in blood pressure.

“Hydrogen sulfide is the stinky gas that can kill workers who encounter it in sewers; but when adminstered to mice in small, controlled doses, within minutes it produces what appears to be totally reversible metabolic suppression,” says Warren Zapol, MD, chief of Anesthesia and Critical Care at MGH and senior author of the Anesthesiology study. “This is as close to instant suspended animation as you can get, and the preservation of cardiac contraction, blood pressure and organ perfusion is remarkable.” ___Eurekalert
Other research in sheep suggests that hydrogen sulfide may not work as well in larger mammals, such as humans. We can learn from the research in mice, but we will probably have to devise more sophisticated ways to trigger human hibernation than inhaled hydrogen sulfide.

Something interesting is going on in the bodies of hibernating animals such as arctic ground squirrels (PDF) that allows them to survive sub-freezing temperatures. Similar factors protect some species of fish and amphibians, which survive below freezing body temperatures. Insect eggs and larvae freeze solid for months, then revive in warm weather.

The best prospect for long-term human stasis (months, years, decades) probably will come from technology that allows the body to be frozen while preventing ice formation in tissues--vitrification. Still, being able to lower metabolic rates chemically--as with hydrogen sulfide--would provide many short-term benefits of hibernation for medical purposes such as trauma surgery and recovery, recovery from stroke, heart attack and hypoxia, and delicate heart and brain surgery.

The research on mice needs to be expanded to larger rodents, and small dogs and cats if possible. By studying the cell signaling processes at work, scientists should be able to devise multi-faceted treatments more suitable to large mammals.

More on cryonic preservation of tissues


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