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)

Armand Karow on Isamu Suda's brain cryopreservation experiments

In 2007, cryobiologist Armand M. Karow passed away. Unlike many contemporary cryobiologists, Karow offered cautious support for the objectives of cryonics. In the mid-1960s, Karow served on the Scientific Advisory Council of the Cryonics Societies of America (CSA). He also published a regular column titled “Scientifically Speaking” in Cryonics Reports, a publication by the Cryonics Society of New York (CSNY).

One of these columns, “The Suda Experiment,” contains his comments on   Isamu Suda’s cat brain experiments. Suda perfused whole cat brains with low concentrations of glycerol and recorded electrical brain wave activity (EEG) after storage at high subzero temperatures and rewarming. But as Karow points out, “the generation of EEG’s is not necessarily an indication of organized, coherent activity… The EEG tracings obtained by Suda probably could have been generated even if a large number of the cells were damaged.”

A similar point can be made about studies that demonstrate viability in brain tissue after long periods  (1 hour) of warm ischemia. Although such studies are helpful to persuade critics of cryonics that cryopreservation or warm ischemia do not (instantly) destroy the brain, there is a tendency in cryonics to selectively highlight studies that are “outliers” in their field to make the case for cryonics. A related issue is the scientific meliorism implicit in the view that whatever can be imagined as not contradicting the laws of chemistry and physics will occur, a view of which the scientific, psychological, and social  aspects will be discussed here in more detail in the future.

Armand Karow – The Suda experiment (Cryonics Reports, 1967)

Cryobiologist Brian Wowk on the Suda experiments and cryonics (Immortality Institute Forum, 2006)