Cryonics

File:Alcor-Dewar2.jpg

This "bigfoot" Dewar flask is custom-designed to contain four wholebody patients and six neuropatients immersed in liquid nitrogen at -196 degrees Celsius. The Dewar is an insulated container which consumes no electric power. Liquid nitrogen is added periodically to replace the small amount that evaporates.

Cryonics is the practice of preserving humans and pets by storing them at cryogenic temperatures -- where metabolism and decay are almost completely stopped -- for the purpose of future reanimation. Cryonics is not a widespread medical practice and is viewed with skepticism by most scientists and doctors today. However, there is a high representation of scientists among cryonicists. It was not long ago that most scientists viewed the idea of cloning with skepticism. Support for cryonics is based on controversial projections of future technologies and of their ability to enable molecular-level repair of tissues and organs.

Viruses, bacteria, sperm/eggs, embryos at early stages of development, insects, and even small animals (small frogs, some fish) can be cryogenically frozen, preserved for an indefinite time (as long as low temperature is maintained) and then thawed and returned to a living state. Large animals or organs (a few centimeters and larger) cannot be safely frozen because removing heat via thick tissue by natural thermoconductivity becomes so slow that ice microcrystals grow big enough to damage cell membranes. This problem can be overcome by the use of cryoprotectants that allow water to vitrify rather than freeze, preventing ice crystals from forming, but only at the expense of toxicity from the cryoprotectants.

A cryogenically preserved organism, whether frozen or vitrified, is said to be cryopreserved. Barring social disruptions, cryonicists believe that a perfectly vitrified person can be expected to remain physically viable for at least 30,000 years, after which time cosmic ray damage is thought to be irreparable. Many scientists in the field, most notably Ralph Merkle and Brian Wowk, hold that molecular nanotechnology has the potential to extend even this limit many times over.

To its detractors, the justification for the actual practice of cryonics is unclear, given the primitive state of preservation technology. Advocates counter that even a slim chance of revival is better than no chance. In the future, they speculate, not only will conventional health services be improved, but they will also quite likely have expanded even to the conquering of old age itself (see links at the bottom). Therefore, if one could preserve one's body (or at least the contents of one's mind) for, say, another hundred years, one might well be resuscitated and live indefinitely long. While technology does not permit revival today, it does, they argue, preserve the detailed structure of the brain very well, making the attempt at preservation a rational, if uncertain, bet on the future. Critics of the field disagree, contending that cryonics, while an interesting technical idea and a valid subject for research, is currently little more than a pipedream, that current "patients" will never be successfully revived, even in the distant future, and that decades of research, at least, must occur before cryonics is to be a legitimate field with any hope of success. Responses to these criticisms note that they do not address what advocates regard as the central issue: whether molecular-level tissue repair will, in fact, prove to be feasible.

Probably the most famous cryopreserved patient is Ted Williams. The popular urban legend that Walt Disney was cryopreserved is false; he was cremated, and interred at Forest Lawn Memorial Park Cemetery. Robert Heinlein, who wrote enthusiastically of the concept, was cremated and his ashes distributed over the Pacific Ocean. Timothy Leary was a long-time cryonics advocate, and signed up with a major cryonics provider. He changed his mind, however, shortly before his death, and so was not cryopreserved.

A cryopreserved person is sometimes whimsically called a corpsicle (a portmanteau of "corpse" and "popsicle"). This term was first used by science fiction author Larry Niven, who credits its formulation to Frederick Pohl.

Obstacles to success

Damage from ice formation and ischemia

Cryonics has traditionally been dismissed by mainstream cryobiology, of which it is arguably a part. The reason generally given for this dismissal is that the freezing process creates ice crystals, which some scientists have claimed damage cells and cellular structures so as to render any future repair impossible. Cryonicists have long argued, however, that the extent of this damage was greatly exaggerated by the critics, presuming that some reasonable attempt is made to perfuse the body with cryoprotectant chemicals (traditionally glycerol) that inhibit ice crystal formation.

According to cryonicists, the ice crystal damage objection became moot around the turn of the millennium, when cryobiologists Greg Fahy and Brian Wowk, of Twenty-First Century Medicine, developed major improvements in cryopreservation technology, including new cryoprotectants and new cryoprotectant mixtures, greatly improving the feasibility of vitrification, and resulting in the near-elimination of ice crystal formation in the brain. Vitrification preserves tissue in a glassy rather than frozen state. In a glass, molecules do not rearrange themselves into grainy crystals as they are cooled, but instead become locked together while still randomly arranged as in a fluid, forming a "solid liquid" as the temperature falls below the glass transition temperature. Alcor Life Extension Foundation, the world's largest cryonics provider, has since been using these cryoprotectants, along with a new, faster cooling method, to vitrify whole human brains. The second-largest cryonics provider in the world, the Cryonics Institute (CI), uses a vitrification solution developed by its in-house cryobiologist, Dr. Yuri Pichugin. CI has developed computer-controlled cooling boxes to ensure that cooling is rapid above T_g ("glass-transition temperature", solidification temperature) and slow below T_g (to reduce fracturing due to thermal stress).

Current solutions being used for vitrification are stable enough to avoid crystallization even when a vitrified brain is warmed up. This has recently allowed brains to be vitrified, warmed back up, and examined for ice damage using light and electron microscopy. No ice crystal damage was found. However, if the circulation of the brain is compromised, protective chemicals may not be able to reach all parts of the brain, and freezing may occur either during cooling or during rewarming. Cryonicists argue, however, that injury caused during cooling might, in the future, be repairable before the vitrified brain is warmed back up, and that damage during rewarming might be prevented by adding more cryoprotectant in the solid state, or by improving rewarming methods. But even given the best vitrification that current technology allows, rewarming still does not allow revival, even if crystallization is avoided, due to the toxic effects of the cryoprotectants. Again, however, cryonicists counter that future technology might be able to overcome this difficulty, and find a way to combat the toxicity after rewarming. If, for example, the toxicity is due to denatured proteins, those proteins could be repaired or replaced.

Some critics have speculated that because a cryonics patient has been declared legally dead, their organs must be dead, and thus unable to allow cryoprotectants to reach the majority of cells. Cryonicists respond that it has been empirically demonstrated that, so long as the cryopreservation process begins immediately after legal death is declared, the individual organs (and perhaps even the patient as a whole) remain biologically alive, and vitrification (particularly of the brain) is quite feasible. This same principle is what allows organs, such as hearts, to be transplanted, even though they come from dead donors.

Cryonics rescue procedures cannot begin until legal pronouncement of death has occurred, and pronouncement is usually based on cessation of heartbeat (only very rarely on brain activity measurements). When the heart stops beating and blood flow ceases, ischemic damage begins. Deprived of oxygen and nutrient, cells, tissues and organs begin to deteriorate. If the heart is restarted after too many minutes have passed, the reintroduced oxygen can cause even more damage due to oxidative stress, a phenomenon known as reperfusion injury. Cryonicists try to minimize ischemice and reperfusion injury beginning cardio-pulmonary support (much like CPR) and cooling as soon as possible after pronouncement of death. Anti-clotting agents like heparin and antioxidants may be administered. Suspended Animation, INC specializes in research-into and implementation-of optimal procedures for minimizing ischemic injury in cryonics rescue.

Revival process

Critics have often quipped that it is easier to revive a corpse than a cryonically frozen body. Many cryonicists might actually agree with this, provided that the "corpse" were fresh, but they would argue that such a "corpse" may actually be biologically alive, under optimal conditions. A declaration of legal death does not mean that life has suddenly ended—death is a gradual process, not a sudden event. Rather, legal death is a declaration by medical personnel that there is nothing more they can do to save the patient. But if the body is clearly biologically dead, having been sitting at room temperature for a period of time, or having been traditionally embalmed, then cryonicists would hold that such a body is far less revivable than a cryonically preserved patient, because any process of resuscitation will depend on the quality of the structural and molecular preservation of the brain.

Cryonicists would also point out that the definitions of "death" and "corpse" currently in use may change with future medical advances, just as they have changed in the past, and so they generally reject the idea that they are trying to "raise the dead," viewing their procedures instead as highly experimental medical procedures, whose efficacy is yet to be either demonstrated or refuted. Some also suggest that if technology is developed that allows mind transfer, revival of the frozen brain might not even be required; the mind of the patient could instead be "uploaded" into an entirely new substrate. The current state of neuro-electrical technology does provide limited control of a computer through neuro-electrical stimulus.

Financial issues

The biggest drawback to current vitrification practice is a costs issue. Because the most cost-effective means of storing a cryopreserved person is in liquid nitrogen, fracturing of the brain occurs, a result of thermal stresses that develop when cooling from −130°C to −196°C (the temperature of liquid nitrogen). Fracture-free vitrification would require inexpensive storage at a temperature significantly below the glass transition temperature of about −125°C, but high enough to avoid fracturing (−130°C is about right). Alcor is currently developing such a storage system. Alcor believes, however, that even before such a storage system is developed, the current vitrification method is far superior to traditional glycerol-based freezing. The fractures are very clean breaks that occur even with traditional glycerol cryoprotection, and the loss of neurological structure is much less than that caused by ice formation, by orders of magnitude.

Cryopreservation arrangements can be expensive, currently ranging from $28,000 at the Cryonics Institute to $150,000 at Alcor and the American Cryonics Society. Most cryonicists fund the costs by making cryonics organizations the beneficiaries of life insurance policies. The elderly, and others who may be uninsurable for health reasons, will often pay for the procedure through their estate. Others simply invest their money over a period of years, accepting the risk that they might die in the meantime. All in all, cryonics is actually quite affordable for the vast majority of those in the industrialized world who really want it, especially if they make arrangements while still young.

Even assuming perfect cryopreservation techniques, many cryonicists would still regard eventual revival as a long shot. In addition to the many technical hurdles that remain, the likelihood of obtaining a good cryopreservation is not very high because of logistical problems. The likelihood of the continuity of cryonics organizations as businesses, and the threat of legislative interference in the practice, don't help the odds either. Most cryonicists, therefore, regard their cryopreservation arrangements as a kind of medical insurance—not certain to keep them alive, but better than no chance at all and still a rational gamble to take.

Head ("neuro") vs. whole-body cryopreservation

During the 1980s, the problems associated with crystallization were becoming better appreciated, but the publication of the book ENGINES OF CREATION by K. Eric Drexler in 1986 aroused a great deal of interest in the idea that nanotechnology would be able to repair freezing damage. Alcor and the American Cryonics Society shifted emphasis from whole body to "neuropreservation" ("neuro", head-only cryopreservation), on the assumption that the rest of the body could be regrown, perhaps by cloning of the person's DNA or reconstructed with nanotechnology. The main goal now seems to be to preserve the information contained in the structure of the brain, on which memory and personal identity depends. Available scientific and medical evidence suggests that the mechanical structure of the brain is wholly responsible for personal identity and memories (for instance, spinal cord injury victims, organ transplant patients, and amputees appear to retain their personal identity and memories). Damage caused by freezing and fracturing is thought to be potentially repairable in the future, using nanotechnology, which will enable the manipulation of matter at the molecular level. To critics, this appears a kind of futuristic deus ex machina, but while the engineering details remain speculative, the rapidity of scientific advances over the past century, and more recently in the field of nanotechnology itself, suggest to some that there may be no insurmountable problems. And the cryopreserved patient can wait a long time. With the advent of vitrification, the importance of nanotechnology to the cryonics movement may begin to decrease.

Some critics, and even some cryonicists, question this emphasis on the brain, arguing that during neuropreservation some information about the body's phenotype will be lost and the new body may feel "unwanted," and that in case of brain damage the body may serve as a crude backup, helping restore indirectly some of the memories. [1] Partly for this reason (as well as for better public relations) , the Cryonics Institute preserves only whole bodies. Some proponents of neuropreservation agree with these concerns, but still feel that lower costs and better brain preservation justify preserving only the brain. About three-quarters of the patients stored at Alcor are "neuros".

History

Historically, cryonics began in 1962 with the publication of The Prospect of Immortality by Robert Ettinger, a founder and the first President of the Cryonics Institute. In the 1970s, the damage caused by crystallization was not well understood. The Cryonics Society of California ran out of money, allowing their patients to thaw out, and its President Robert Nelson was sued, at which point the practice gained something of the reputation of a scam. During the 1980s, the extent of the damage from the freezing process became much clearer and better known, and the emphasis of the movement began to shift to the capabilities of nanotechnology.

Before Alcor moved to Arizona from Riverside, California in 1994, it was the center of several controversies, including a county coroner's ruling that a client was murdered with barbiturates by the company's staff, prior to her neuropreservation. Alcor contended that the drug was administered after her death. No charges were ever filed. When the baseball star Ted Williams was cryonically preserved by Alcor in 2002 a family dispute arose as to whether Ted had really wanted to be cryopreserved. Following a July, 2003 Sports Illustrated article claiming that Alcor had mishandled Ted Williams, Alcor had to fight for its existence in the Arizona legislature. Despite not being responsible for Ted Williams, the media blitz resulted in the Cryonics Institute (CI) being placed under a "Cease and Desist" order by the State of Michigan for six months. Finally the Michigan government decided to regulate CI as a cemetery.

Alcor currently preserves about 70 human bodies and heads in Scottsdale, Arizona and the Cryonics Institute has about the same number of cryonics patients in its Clinton Township, Michigan facility. There are no cryonics service providers outside of the United States, although there are support groups in Europe, Canada, Australia and the United Kingdom.

See also:

• Senescence,
• engineered negligible senescence
• life extension,
• Interstellar travel,
• Biostasis,
• Immortality Institute,
• Hibernation

External links

• Cryonics FAQ
• sci.cryonics Usenet newsgroup
• CryoNet
• The First Immortal Free download of popular, critically acclaimed cryonics novel
• Ralph Merkle's introduction to cryonics
• Alcor Life Extension Foundation
• Cryonics Institute
• American Cryonics Society
• Cryonics Europe
• Cryonics Society - Resources and Advocacy
• Cryonics Society of Canada
• The Immortality Institute
• Longevity Meme
• The NanoAging Institute
• Article about cooling dogs to near-freezing temperatures (7 °C) for 3 hours, then reanimating them. Dogs were NOT "frozen."