Despite the popular myth, Walt Disney’s body was not frozen. In fact, Disney died a year before the first man was cryogenically preserved. Cryonics, the study of preserving tissues by lowering them to very low temperatures, can be traced back to the 1960’s to a professor of physics at Wayne State University named Robert Ettinger (1). Ettinger, considered to be the “father of cryonics,” just died last year at 92 (1). His body remains cryogenically preserved in a facility just outside of Detroit, MI (1).

In his 1962 book Prospect of Immortality, Ettinger described the moral and practical characteristics of cryogenic preservation (1). The manifesto struck a public nerve during a time when people were already frayed by the Cold War and the general intellectual uncertainty of the time, including the development of such things as the atomic bomb, microwave ovens, and Sputnik (1). Ettinger’s ideas did not seem impossible. While most academics handedly dismissed Ettinger, his ideas launched him into instant public celebrity.

Ettinger’s legion of followers became known as the “Cryonics Movement” (2). Within three years, the first person entered cryogenic suspension (2). Many more followed, and soon several cryogenic preservation facilities were built to match rising demand. However, over the course of the ensuing decades, declining interest and poor economic periods saw the movement die down (2). Many cryogenic organizations declared bankruptcy, and the abandonment of their facilities resulted in the thawing of several preserved bodies (2).

Today, two organizations remain that offer cryonic preservation: Alcor Life Extension Foundation and the Cryonics Institutes (CI). Both are listed as non-profit organizations, subsiding primarily on bequests and donations (3, 4). As of 2011, Alcor and the Cryonics Institute each have approximately 1000 members, including 110 cryogenically preserved humans and several dozen domestic pets (3, 4) Members pay monthly fees and a final sum for a total cost of approximately $200,000 to be preserved (3, 4). In many cases, life insurance will pay these costs (3, 4).

The Science

How does cryonic preservation work, and why it is considered by many to be a pseudoscience? Cryogenics is the physical study of molecules at very low temperatures—typically 77 Kelvin, or -196˚C (4). Cryonics is the preservation of human and animal tissues at these temperatures (4).  Tissues can be preserved by the cold because chemical reactions and thus tissue-degrading metabolic events cease at these temperatures, reaching what is called the glass transition state (-202˚C) (5). It is for this reason, that tissues can theoretically be kept for up to 10,000 years (3). Beyond this point, cells will begin to decay due to cosmic radiation from the sun (3).

The point of contention that has gripped cryonics has been the revival of these chronically preserved tissues, which are damaged in the cooling process.

Water is at the root of this issue. When lowering tissues to such temperatures, the formation of ice crystals within cells, which are typically 70% water, will lyse their membranes (5). Thus when thawed, cells will have lost their structural integrity in the same way frozen goods, such as fruits, are not as firm as they were before they were put in a freezer (5).

Vitrification, a process that seeks to replace water with glycol-based anti-freezes or cryoprotectants, has sought to amend this issue, but has so far found limited success (5). A rabbit liver has been removed, vitrified and returned to rabbits in working order by scientists (6). The same process has been done in brain tissue and human embryos as well as whole animals including dogs and monkeys, though in all cases tissues were lowered to only 0˚C (6). Much less success has been seen in whole human bodies, naturally a more nuanced system.

If an individual has elected to be cryogenically preserved, the process of his or her vitrification begins immediately upon death (3). While legal death is cardiac, studies have found that brain activity continues upwards of 6 minutes after the heart stops beating (3). The goal of Alcor and CI is to preserve their client in this time frame. Bodies are first cooled on a bed of dry ice, and then dehydrated of 60% of their water (3, 4). The fluids are replaced with cryoprotectants that are pumped through the circulatory system (3, 4). Clients are then placed in large cylinders of liquid nitrogen, which are kept at -202˚C (3, 4)

This process limits the tissue damage done to the body, but does not prevent it. Though most water is removed, water damage inevitably occurs. This happens within the cell as described, but also between cells. Extracellular fluid can crystalize, assisting in the rupture of adjacent cell membranes. Chemical damage is also caused. Water-soluble enzymes and chemicals are pushed out of solution in the crystal forming process, becoming concentrated doses that are fatal when tissues are thawed (7).

The cryoprotectants themselves also pose a hazard. In addition to glycol-based chemicals, they also contain dimethysulfoxide (DMSO), which is strongly toxic at non-freezing temperatures. Effective methods for removing cryoprotectants in humans and replacing it in blood have not yet been developed (8).

Another source of damage is oxygen toxicity. Large quantities of pure oxygen are known to remove single electrons from molecules within the respiratory system of cells, creating highly reactive molecules known as free radicals (9). Radicals destroy DNA and proteins, killing or irreparably damaging the cell (9). Rats resuscitated with above-normal concentrations of oxygen were found to suffer from brain damage and cerebral palsy whereas those given normal quantities more or less lacked symptoms, according to researchers at the University of Texas Southwestern (9). Similar results have been found in heart attack victims who suddenly die after being revived with pure oxygen (10). There is no method by which to reintroduce oxygen to a cryogenically preserved body in a gradual and safe manner.

These issues associated with the preservation and reanimation process are not to mention the initial causes of death. Whether the individual died of disease or old age, a method to amend the cause of death would have to be developed before any revival could be considered. Given that death is usually a combination of both, medical science will likely develop the ability to stop aging and disease before finding any method to reverse either process.

Revival and the Future

Supporters of cryogenics propose that nanotechnology holds the answer to effective preservation and revival. As bodies are warmed, microscopic machines will repair damage to individual cells (3). Yet, Alcor and CI both admit that such technology is not in the visible future (3, 4). In truth, there is no apparent method to revive a cryogenically preserved body. The possibility that nanomanchines could rebuild tissues molecule by molecule for the trillions of cells in the body is fantastically unrealistic by any scientific measure (5).

Proponents of cryogenic preservation assert that their study has not gained the support of mainstream science because of the specialized nature of academic study and the multidisciplinary study needed in cryonics (3, 4). They also propose that many academics are too afraid to endorse such practice since doing so may overshadow their own work (3).

Nonetheless, it cannot be argued that the cryogenic preservation is at the least incomplete. Indeed, the cryonics of cell samples and organisms is quite established. The storage of blood, tissue samples, semen, human eggs, embryos, ovarian tissues and plant seeds is ubiquitous (5). However, applying the same method to human bodies is an exponentially more difficult task, and a metaphorical one-way trip (11).

It is for this reason that critics of cryogenic preservation maintain that the study is a pseudoscience (11). Many anthropologists argue that cryonics is a cultural manifestation of “anxieties about aging time and the future” more so than any real science (12). Still, some argue that cryonics should not be entirely disregarded. As one academic put it: “It emerges that it might be imprudent not to use the technology, given the relatively minor expense involved and the potential payoff” (13). Indeed, winning the lottery is effectively impossible, but one must buy the ticket if he/she stands a chance to win.

References

1.     E. Brown, Robert Ettinger, founder of the cryonics movement, dies at 92 (2011). Available at http://www.washingtonpost.com/local/obituaries/from-phyics-teacher-to-founder-of-the-cryonics-movement/2011/07/24/gIQAupuIXI_story.html. (20 December 2011).

2.     C. Tandy, The Philosophy of Robert Ettinger (Parkland, Florida, Universal Publishers, 2002).

3.     Cryonics: Alcor Life Extension Foundation (2010). Available at http://www.alcor.org/index.html (20 December 2011)

4.     Cryonics Institute Cryonics Institute. (2009) Available at http://www.cryonics.org (20 December 2011).

5.     B. Best, Rejuvenation Res. 11, 493-503 (2008)

6.     G. Fahy, B. Wowk, R. Pagotan, A. Chang, Organogenesis 5, 167-175 (2009)

7.     P. Mazur, Am. J. Physiol- Cell Physiol. 247, C125-42 (1984).

8.     C. Platt, New Brain Study Shows Reduced Tissue Damage (1995). Available at http://www.alcor.org/Library/html/braincryopreservation1.html (21 December 2011).

9.     J. Koch et al., J. Cereb. Blood Flow Metab. 28 1294-1306 (2008).

10.   Y. Qin et al., Am. J. Physiol- Heart Circ. Physiol. 286, H2280-6 (2004).

11.   M. Shermer Sci. Am. 285, 29 (2001)

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12.   T. Romain, Med. Anthropol. 29, 194-215 (2010).

13.   D. Shaw, Bioethics 23, 515-521 (2009).