Cryonics

Technicians prepare a body for cryopreservation in 1985.

Cryonics (from Greek κρύος 'kryos-' meaning 'cold') is the low-temperature preservation (usually at -196°C) of people who cannot be sustained by contemporary medicine, with the hope that resuscitation and restoration to full health may be possible in the far future.^[1] Cryopreservation of humans is not reversible with present technology; cryonicists hope that medical advances will someday allow cryopreserved people to be revived.^[2]

Cryonics is regarded with skepticism within the mainstream scientific community and is not part of normal medical practice. It is not known if it will ever be possible to revive a cryopreserved human being. Cryonics depends on beliefs that death is a process rather than an event,^[3] clinical death is a prognosis of death rather than a diagnosis of death,^[4] and that the cryonics patient has not experienced information-theoretic death.^[5] Such views are at the speculative edge of medicine.^[6]

Cryonics procedures can only begin after legal death, and cryonics "patients" are considered legally dead. Cryonics procedures ideally begin within minutes of cardiac arrest,^[7] and use cryoprotectants to prevent ice formation during cryopreservation.^[8] The first human being to be cryopreserved was Dr. James Bedford in 1967.^[9] As of 2014, about 250 people were cryopreserved in the United States, with 1500 more having made arrangements for cryopreservation after their legal death.^[10]

Theory

Long-term memory is stored in cell structures and molecules within the brain.^[11] In surgeries on the aortic arch, hypothermia is used to cool the body while the heart is stopped; this is done primarily to spare the brain by slowing its metabolic rate, reducing the need for oxygen, and thus reducing damage from lack of oxygen. The metabolic rate can be reduced by around 50% at 28 °C, by around 80% at 18 °C or profound hypothermia. By keeping the brain at around 25 °C, (considered deep hypothermia), surgeries can stretch to be around a half-hour with very good neurological recovery rates; stretching that to 40 minutes increases the risk of short term and long term neurological damage.^[12]

Cryonics goes further than the mainstream consensus that the brain doesn't have to be continuously active to survive or retain memory. Cryonics controversially asserts that a human person survives even within an inactive brain that's been badly damaged provided that original encoding of memory and personality can, in theory, be adequately inferred and reconstituted from structure that remains.^[5][10][13] Cryonicists argue that as long as brain structure remains intact, there is no fundamental barrier, given our current understanding of physical law, to recovering its information content. Cryonicists consider a cryonics "patient" who has been declared legally dead to possibly still be alive by information theoretic criteria, and argue that true "death" should be defined as irreversible loss of brain information critical to personal identity, rather than inability to resuscitate using current technology.^[5] The cryonics argument that death doesn't occur as long as brain structure remains intact and theoretically repairable has received some mainstream medical discussion in the context of the ethical concept of brain death and organ donation.^[14][15][16]

Cryonics uses temperatures below -130°C, called cryopreservation, in an attempt to preserve enough brain information to permit future revival of the cryopreserved person. Cryopreservation may be accomplished by freezing, freezing with cryoprotectant to reduce ice damage, or by vitrification to avoid ice damage. Even using the best methods, cryopreservation of whole bodies or brains is very damaging and irreversible with current technology.

Cryonics requires future technology to repair or regenerate tissue that is diseased, damaged, or missing. Brain repairs in particular will require analysis at the molecular level. This far future technology is usually assumed to be nanomedicine based on molecular nanotechnology.^[17][18][19] Biological repair methods^[20] or mind uploading^[21] have also been proposed.

Practice

Costs can include payment for medical personnel to be on call for death, vitrification, transportation in dry ice to a preservation facility, and payment into a trust fund intended to cover indefinite storage in liquid nitrogen and future revival costs.^[22][23] As of 2011, U.S. cryopreservation costs can range from $28,000 to $200,000, and are often financed via life insurance.^[22] KrioRus, which stores bodies communally in large dewars, charges $12,000 to $36,000 for the procedure.^[24] Some patients opt to have only their head, rather than their whole body, cryopreserved. As of 2016, four facilities exist in the world to retain cryopreserved bodies; three are in the U.S., and one is in Russia.^[2][25] As of 2014, about 250 people have been cryogenically preserved in the U.S., and around 1500 more have signed up to be preserved.^[10]

Obstacles to success

Preservation injury

Long-term preservation of biological tissue can be achieved by cooling to temperatures below -130°C.^[26] Immersion in liquid nitrogen at a temperature of -196°C (77 Kelvin) is often used for convenience. Low temperature preservation of tissue is called cryopreservation. Contrary to popular belief, water that freezes during cryopreservation is usually water outside cells, not water inside cells. Cells don't burst during freezing, but instead become dehydrated and compressed between ice crystals that surround them. Intracellular ice formation only occurs if the rate of freezing is faster than the rate of osmotic loss of water to the extracellular space.^[26]

Without cryprotectants, cell shrinkage and high salt concentrations during freezing usually prevent frozen cells from functioning again after thawing. In tissues and organs, ice crystals can also disrupt connections between cells that are necessary for organs to function.^[27] The difficulties of recovering large animals and their individual organs from a frozen state have been long known. Attempts to recover frozen mammals by simply rewarming them were abandoned by 1957.^[28] At present, only cells, tissues, and some small organs can be reversibly cryopreserved.^[29][30]

When used at high concentrations, cryoprotectants can stop ice formation completely. Cooling and solidification without crystal formation is called vitrification.^[31] The first cryoprotectant solutions able to vitrify at very slow cooling rates while still being compatible with whole organ survival were developed in the late 1990s by cryobiologists Gregory Fahy and Brian Wowk for the purpose of banking transplantable organs.^[30][32][33] This has allowed animal brains to be vitrified, warmed back up, and examined for ice damage using light and electron microscopy. No ice crystal damage was found;^[34] remaining cellular damage was due to dehydration and toxicity of the cryoprotectant solutions. Large vitrified organs tend to develop fractures during cooling,^[35] a problem worsened by the large tissue masses and very low temperatures of cryonics.^[36]

The use of vitrification rather than freezing for cryonics was anticipated in 1986, when K. Eric Drexler proposed a technique called fixation and vitrification, anticipating reversal by molecular nanotechnology.^[37] In 2016, Robert L. McIntyre and Gregory Fahy at the cryobiology research company 21st Century Medicine, Inc. won the Small Animal Brain Preservation Prize of the Brain Preservation Foundation by demonstrating to the satisfaction of neuroscientist judges that a particular implementation of fixation and vitrification called aldehyde-stabilized cryopreservation^[38] could preserve a rabbit brain in "near perfect" condition at -135°C, with the cell membranes, synapses, and intracellular structures intact in electron micrographs.^[39][40][41] Brain Preservation Foundation President, Ken Hayworth, said, "This result directly answers a main skeptical and scientific criticism against cryonics—that it does not provably preserve the delicate synaptic circuitry of the brain.”^[42] However the price paid for perfect preservation as seen by microscopy was tying up all protein molecules with chemical crosslinks, completely eliminating biological viability. Actual cryonics organizations use vitrification without a chemical fixation step,^[43] sacrificing some structural preservation quality for supposedly less damage at the molecular level.

While preservation of both structure and function has been possible for brain slices using vitrification,^[44] this goal remains elusive for whole brains. In absence of a revived brain, or brain simulation from somehow scanning a preserved brain, the adequacy of present vitrification technology (with or without fixation) for preserving the anatomical and molecular basis of long-term memory as required by cryonics is still unproven.

Outside the cryonics community, many scientists have a blanket skepticism toward existing preservation methods. Cryobiologist Dayong Gao states that "we simply don't know if (subjects have) been damaged to the point where they've 'died' during vitrification because the subjects are now inside liquid nitrogen canisters." Biochemist Ken Storey argues (based on experience with organ transplants), that "even if you only wanted to preserve the brain, it has dozens of different areas, which would need to be cryopreserved using different protocols."^[45]

Revival

Those who believe that revival may someday be possible generally look toward advanced bioengineering, molecular nanotechnology,^[46] or nanomedicine^[19] as key technologies. Revival would require repairing damage from lack of oxygen, cryoprotectant toxicity, thermal stress (fracturing), freezing in tissues that do not successfully vitrify, and reversing the effects that caused death. In many cases extensive tissue regeneration would be necessary.

According to Cryonics Institute president Ben Best, cryonics revival may be similar to a last in, first out process. People cryopreserved in the future, with better technology, may require less advanced technology to be revived because they will have been cryopreserved with better technology that caused less damage to tissue. In this view, preservation methods would get progressively better until eventually they are demonstrably reversible, after which medicine would begin to reach back and revive people cryopreserved by more primitive methods.^[47]

Alternatively, some cryonicists propose that a brain could be electronically scanned and uploaded into a digital computer using hypothetical far-future technology. For some, this raises a philosophical issue: would such an upload "actually be you"; would it be "a new person who is like you but whose conscious experience you don’t have access to"; or would it merely be a "philosophical zombie"?^[2][23]

Legal issues

Legally, most countries treat preserved individuals as deceased persons because of laws that forbid vitrifying someone who is medically alive.^[47] Cryonics providers tend to be treated as medical research institutes. In France, cryonics is not considered a legal mode of body disposal;^[48] only burial, cremation, and formal donation to science are allowed. However, bodies may legally be shipped to other countries for cryonic freezing.^[49] As of 2015, the Canadian province of British Columbia prohibits the sale of arrangements for body preservation based on cryonics.^[50] In Russia, cryonics falls outside both the medical industry and the funeral services industry, making it easier in Russia than in the U.S. to get hospitals and morgues to release cryonics candidates.^[24]

Ethics

Writing in Bioethics, David Shaw examines the ethical status of cryonics. The arguments against it include changing the concept of death, the expense of preservation and revival, lack of scientific advancement to permit revival, temptation to use premature euthanasia, and failure due to catastrophe. Arguments in favor of cryonics include the potential benefit to society, the prospect of immortality, and the benefits associated with avoiding death. Shaw explores the relatively minor expense and the potential payoff, and applies it to an adapted version of Pascal's Wager.^[51]

History

20th century

In 1922 Alexander Yaroslavsky, member of Russian immortalists-biocosmists movement, wrote "Anabiosys Poem". However, the modern era of cryonics began in 1962 when Michigan college physics teacher Robert Ettinger proposed in a privately published book, The Prospect of Immortality,^[52] that freezing people may be a way to reach future medical technology. (The book was republished in 2005 and remains in print.) Even though freezing a person is apparently fatal, Ettinger argued that what appears to be fatal today may be reversible in the future. He applied the same argument to the process of dying itself, saying that the early stages of clinical death may be reversible in the future. Combining these two ideas, he suggested that freezing recently deceased people may be a way to save lives. In 1955 James Lovelock was able to reanimate rats frozen at 0 Celsius using microwave diathermy.^[53]

Robert Ettinger during WWII

Slightly before Ettinger’s book was complete, Evan Cooper^[54] (writing as Nathan Duhring) privately published a book called Immortality: Physically, Scientifically, Now that independently suggested the same idea. Cooper founded the Life Extension Society (LES) in 1964 to promote freezing people. Ettinger came to be credited as the originator of cryonics, perhaps because his book was republished by Doubleday in 1964 on recommendation of Isaac Asimov and Fred Pohl, and received more publicity. Ettinger also stayed with the movement longer.

The first person was cryopreserved in 1967 (James Bedford). In the U.S., cryonics took a reputation hit around the 1970s: the Cryonics Society of California, led by a former TV repairman named Robert Nelson with no scientific background, ran out of money to maintain cryopreservation of existing patients; Nelson was sued for allowing nine bodies to decompose.^[24]

Demographics

Cryonicists are predominantly nonreligious white males; according to the New York Times, among living cryonicists, men outnumber women by about three to one.^[55] According to The Guardian, most cryonicists used to be "young, male and geeky", but recent demographics may have shifted a bit toward whole families.^[47]

In 2015 Du Hong, a 61-year-old female writer of children's literature, became the first known Chinese person to be cryopreserved.^[56]

Public reception

Some scientists have expressed skepticism about cryonics in media sources,^[24] however the number of peer-reviewed papers on cryonics is limited because its speculative aspects place it outside of the focus of most academic fields.^[10] While most neuroscientists agree that all the subtleties of a human mind are contained in its anatomical structure,^[57] few neuroscientists will comment directly upon the topic of cryonics due to its speculative nature. Individuals who intend to be frozen are often "looked at as a bunch of kooks", despite many of them being scientists and doctors.^[58]

At the extreme, some people are openly hostile to the idea of cryonics.^[2]

According to cryonicist Aschwin de Wolf and others, cryonics can often produce intense hostility from spouses who are not cryonicists. James Hughes, the executive director of the pro-life-extension Institute for Ethics and Emerging Technologies, chooses not to personally sign up for cryonics, calling it a worthy experiment but stating laconically that "I value my relationship with my wife."^[55]

Cryobiologist Dayong Gao states that "People can always have hope that things will change in the future, but there is no scientific foundation supporting cryonics at this time."^[45] Alcor disagrees, stating that "There are no known credible technical arguments that lead one to conclude that cryonics, carried out under good conditions today, would not work."^[22]

Many people assert there would be no point in being revived in the far future, if their friends and families are dead.^[51] While it's universally agreed that "personal identity" is uninterrupted when brain activity temporarily ceases during incidents of accidental drowning (where people have been restored to normal functioning after being completely submerged in cold water for up to 66 minutes), some people express concern that a centuries-long cryopreservation might interrupt their conception of personal identity, such that the revived person would "not be you".^[10]

In fiction

Suspended animation is a popular theme in science fiction and fantasy settings, appearing in comic books, films, literature, and television. A survey in Germany found that about half of the respondents were familiar with cryonics, and about half of those familiar with cryonics had learned of the subject from films or television.^[59] Some commonly known examples of cryonics being used in popular culture include, Vanilla Sky, Futurama, and Nip/Tuck.^[60]

Famous people

Famous people who are cryopreserved

Among the cryopreserved are James Bedford,^[61] Dick Clair,^[61] L. Stephen Coles (in 2014),^[62] Thomas K. Donaldson,^[61] FM-2030,^[61] Hal Finney^[63] (in 2014), Jerry Leaf,^[61] John-Henry Williams,^[61] and Ted Williams.^[64]

Famous people associated with cryonics but who were not cryopreserved

The urban legend suggesting Walt Disney was cryopreserved is false; he was cremated and interred at Forest Lawn Memorial Park Cemetery.^[65][66] Robert A. Heinlein, who wrote enthusiastically of the concept in The Door into Summer (serialized in 1956), was cremated and had his ashes distributed over the Pacific Ocean. Timothy Leary was a long-time cryonics advocate and signed up with a major cryonics provider, but he changed his mind shortly before his death and was not cryopreserved.

See also

• Chemical brain preservation
• Cryogenics
• Cryptobiosis
• Extropianism
• Hibernation
• Indefinite lifespan
• Information-theoretic death
• KrioRus
• Life extension
• Nanomedicine
• Neuropreservation
• Supercooling
• Suspended animation
• Vitrification in cryopreservation

References

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External links

• Cryonics at DMOZ