Cryonics (from Greek κρύος kryos meaning 'cold') is the low-temperature preservation (usually at −196°C) of a human corpse, with the hope that resuscitation and restoration to life and full health may be possible in the future. Cryopreservation of humans is not reversible with present technology; cryonicists hope that medical advances will someday allow cryopreserved bodies to be revived.
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 cadaver. Cryonics depends on beliefs that the frozen body has not experienced information-theoretic death. Such views are at the speculative edge of science.
Cryonics procedures can only begin after clinical death, and cryonics "patients" are legally dead. Cryonics procedures ideally begin within minutes of death, and use cryoprotectants to prevent ice formation during cryopreservation. The first corpse to be cryopreserved was that of Dr. James Bedford in 1967. As of 2014, about 250 bodies were cryopreserved in the United States, and 1,500 people had made arrangements for cryopreservation after their legal death.
Long-term memory is stored in cell structures and molecules within the brain. 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, and 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.
Cryonics goes further than the mainstream consensus that the brain does not have to be continuously active to survive or retain memory. Cryonics controversially asserts that a human survives even within an inactive brain that has been badly damaged, provided that original encoding of memory and personality can, in theory, be adequately inferred and reconstituted from structure that remains. 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 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. The cryonics argument that death does not 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.
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. Biological repair methods or mind uploading have also been proposed.
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. As of 2011, U.S. cryopreservation costs can range from $28,000 to $200,000, and are often financed via life insurance. KrioRus, which stores bodies communally in large dewars, charges $12,000 to $36,000 for the procedure. Some patients opt to have only their brain cryopreserved, rather than their whole body.
As of 2016, four facilities exist in the world to retain cryopreserved bodies; three are in the U.S., and one is in Russia. As of 2014, about 250 people have been cryogenically preserved in the U.S., and around 1,500 more have signed up to be preserved.
Obstacles to success
Long-term preservation of biological tissue can be achieved by cooling to temperatures below −130°C. Immersion in liquid nitrogen at a temperature of −196 °C (77 kelvins and −320.8 °F) 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.
Without cryoprotectants, 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. 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. At present, only cells, tissues, and some small organs can be reversibly cryopreserved.
When used at high concentrations, cryoprotectants can stop ice formation completely. Cooling and solidification without crystal formation is called vitrification. 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. 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; remaining cellular damage was due to dehydration and toxicity of the cryoprotectant solutions. Large vitrified organs tend to develop fractures during cooling, a problem worsened by the large tissue masses and very low temperatures of cryonics.
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. 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 could preserve a rabbit brain in "near perfect" condition at −135°C, with the cell membranes, synapses, and intracellular structures intact in electron micrographs. 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.” 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, sacrificing some structural preservation quality for less damage at the molecular level. Some scientists, like Joao Pedro Magalhaes, have questioned whether using a deadly chemical for fixation eliminates the possibility of biological revival, making chemical fixation unsuitable for cryonics.
While preservation of both structure and function has been possible for brain slices using vitrification, 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."
Those who believe that revival may someday be possible generally look toward advanced bioengineering, molecular nanotechnology, or nanomedicine 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 cause of 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.
Historically, a person had little control regarding how their body was treated after death as religion had jurisdiction over the disposal of the body. However, secular courts began to exercise jurisdiction over the body and use discretion in carrying out of the wishes of the deceased person. Most countries legally treat preserved individuals as deceased persons because of laws that forbid vitrifying someone who is medically alive. In France, cryonics is not considered a legal mode of body disposal; only burial, cremation, and formal donation to science are allowed. However, bodies may legally be shipped to other countries for cryonic freezing. As of 2015, the Canadian province of British Columbia prohibits the sale of arrangements for body preservation based on cryonics. 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.
In London in 2016, the English High Court ruled in favor of a mother's right to seek cryopreservation of her terminally ill 14-year-old daughter, as the girl wanted, contrary to the father's wishes. The decision was made on the basis that the case represented a conventional dispute over the disposal of the girl's body, although the judge urged ministers to seek "proper regulation" for the future of cryonic preservation following concerns raised by the hospital about the competence and professionalism of the team that conducted the preservation procedures. In Alcor Life Extension Foundation v. Richardson, the Iowa Court of Appeals ordered for the disinterment of Richardson, who was buried against his wishes for cryopreservation.
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 expense and the potential payoff, and applies an adapted version of Pascal's Wager to the question.
Cryopreservation was applied to human cells beginning in 1954 with frozen sperm, which was thawed and used to inseminate three women. Ten years later, the freezing of humans was first scientifically proposed by Michigan professor Robert Ettinger. In April 1966, the first human body was frozen with some thought of future reanimation, though it had been embalmed for two months. The body was placed in liquid nitrogen, and stored at just above freezing. The middle-aged woman from Los Angeles, whose name is unknown, was soon thawed out and buried by relatives.
The first body to be truly cryopreserved was James Bedford's a few hours after his cancer-caused death in 1967. He is the only cryonics patient frozen before 1974 still preserved today. Cryonics gained a poor reputation in the U.S. in the late 1970s after the Cryonics Society of California ran out of money to maintain cryopreservation of existing patients. Robert Nelson, a former TV repairman with no scientific background (who had processed Bedford's freezing before turning the body over to relatives), was sued for allowing nine bodies to decompose.
In 2018, a Y-Combinator startup called Nectome was recognized for developing a method of preserving brains with chemicals rather than by freezing. The method is fatal, performed as euthanasia under general anethesia, but the hope is that future technology would allow the brain to be physically scanned into a computer simulation, neuron by neuron.
According to The New York Times cryonicists are predominantly nonreligious white males, outnumbering women by about three to one. According to The Guardian, as of 2008, while most cryonicists used to be young, male and "geeky" recent demographics have shifted slightly towards whole families.
Some scientists have expressed skepticism about cryonics in media sources, 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. While most neuroscientists agree that all the subtleties of a human mind are contained in its anatomical structure, 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.
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."
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." 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." As well, while it is 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".
Suspended animation is a popular subject 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. Some commonly known examples of cryonics being used in popular culture include Demolition Man (film), Vanilla Sky, Fallout 4, Futurama, Passengers and Nip/Tuck.
Notable people who are cryopreserved
Notable 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. 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.
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Cryonics, which began in the Sixties, is the freezing – usually in liquid nitrogen – of human beings who have been legally declared dead. The aim of this process is to keep such individuals in a state of refrigerated limbo so that it may become possible in the future to resuscitate them, cure them of the condition that killed them, and then restore them to functioning life in an era when medical science has triumphed over the activities of the Grim Reaper.
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