Tag: Depressed Metabolism

The purple prose of suspended animation

Esquire magazine features an article on scientist Mark Roth and his research into “suspended animation.” As the website title “The Mad Scientist Bringing Back the Dead…. Really” indicates, this is not supposed to be a detailed account of Ikaria’s recent advances in induction of depressed metabolism but a sensationalist piece on mad scientists. Although the piece states that “Ikaria’s first suspended-animation product” has “completed Phase 1 trials in Australia and Canada” and is “being tested on humans, to make sure it’s safe” it remains to be seen if this technology involves major advances in rapid induction of depressed metabolism in humans or offers just another treatment option for various hypoxic-ischemic conditions as the press release (pdf) seems to indicate.

The article misses a number of opportunities to set the record straight on the proper use of terminology and prevailing definitions of death. The ability to resuscitate an organism from circulatory arrest, depressed metabolism, or suspended animation implicates that the organism was not dead to start with. This is not just a matter of semantics. The phenomenon of death is surrounded by many cultural and religious taboos and the difference between saying that we can  bring back the dead instead of  observing that recent advances in science and medicine requires us to redefine our definition of death  is not a trivial matter. Most religious people do not object to cardiopulmonary resuscitation or hypothermic circulatory arrest because they do not believe that a patient who is resuscitated in such medical procedures was (temporarily) dead. The word death should be reserved for a condition in which integrated biological function cannot be restored by either contemporary or future technological means.

Increasingly, the phrase “suspended animation” is thrown around to describe a number of distinct phenomena ranging from modest drops in metabolism to complete metabolic arrest. If the word  is taken literally, however, only complete metabolic arrest constitutes real suspended animation. Such a state cannot be achieved in humans by the use of hydrogen sulfide (or its injectable derivatives) and requires either the use of extreme cold such as practiced through vitrification in cryonics or the use of advanced nanotechnology in warm biostasis.

Popular reports on recent developments in “suspended animation” do not carefully distinguish between the results obtained with hydrogen sulfide and carbon monoxide in C. elegans and mice and its applications in humans. Until more detailed information is available on the use of these substances in large animals or humans it should not be assumed  that rapid pharmacological induction of depressed metabolism in humans is a clinical possibility.

Human cryo-anabiosis

Recent advances with the use of hydrogen sulfide, carbon monoxide and “hibernation induction triggers” to depress metabolism in animal models have  renewed interest  in the possibility of human hibernation.  The ability to drastically depress human metabolism without the use of cold (or in combination with cold) would have a number of important medical and scientific applications including the stabilization of trauma patients, prolonging the time of safe circulatory arrest in surgery, and space travel.

In 2007, the author published a review of the field of depressed metabolism for Alcor’s Cryonics Magazine and expressed skepticism about the prospect of real hibernation in humans any time soon. But this does not mean that we cannot learn from natural hibernators to identify metabolic pathways that can be inhibited to prolong the period the brain can sustain circulatory arrest at normothermic and hypothermic temperatures. As evidenced by the remarkable period myocardium can sustain energy deprivation and still recover, there is still a lot about human metabolism that remains obscure.

Like many ideas in biogerontology, the idea of chemically manipulating human metabolism as a medical procedure to prolong or save lives has gone through various cycles of optimism and disillusion. In his 1969 book Suspended Animation, the author Robert Prehoda presented a number of proposals to manipulate  metabolism in humans. Another person who wrote about depressed metabolism, or “human anabiosis,” was the cryobiologist Armand Karow (1941-2007). During the year 1967 Karow wrote a 5 part series on the science and prospect of depressed metabolism in humans for Cryonics Reports which is made available for this first time online. Although Karow devotes most of his series to the technical obstacles to achieve real suspended animation using cryogenic temperatures, he also discusses the use of metabolic inhibitors to protect vulnerable organs during cooldown to cryogenic temperatures.

Armand Karow – Goal: Human Cryo-Anabiosis (1967)