Cryonics

Summary

Cryonics is a theoretical life support technology, which involves stabilizing the condition of a terminally ill patient via freezing until a future date when technology will be able to revive that person and hopefully return them to a normal life. Storing a person at the temperature of liquid nitrogen (-196 degrees Celsius) can prevent further tissue damage indefinitely. However, the freezing process inflicts a degree of tissue damage that is not reversible by existing technology. Modern technology is successful in freezing sperm, ova (eggs), and embryos, which can later be thawed and restored to life. Human embryos have been thawed, implanted into a uterus, and ultimately developed into a healthy newborn.

Definition and Basic Principles

Cryonics (from the Greek krýos, which means "icy cold") involves the freezing, or cryopreservation, of an entire body or the brain until a future date when technology can thaw the tissue and restore life. If only the brain is frozen, the ultimate goal is to grow or build a new body around the head, using whatever processes are available. The brain is customarily frozen with the head to protect the structure. In the United States, the process begins when a patient's heart stops beating. In addition to humans, some cryonics facilities preserve pets. Once frozen in liquid nitrogen and properly stored, the body will not deteriorate further. Future thawing methods are purely hypothetical. As the technology improves, so will the chances of life restoration.

Cryonics is often confused with cryogenics, which is a separate, broader field concerned with the physics of extremely low temperatures. Unlike cryonics, which focuses on the preservation of organic tissue, cryogenics involves all kinds of matter and the changes matter goes through at temperatures at or approaching absolute zero. Cryogenics is a well-established science with many theoretical and practical applications, while cryonics is highly experimental and relatively limited.

A number of biological specimens have been cryopreserved, stored in liquid nitrogen, and revived. They include insects, eels, and organs. For example, in 2005, a cryopreserved rabbit kidney was thawed and transplanted to a rabbit. The organ functioned normally. The best examples of restoration of viability after cryopreservation of human tissue are ova (eggs), sperm, embryos, and ovarian tissue. A frozen ovum can be thawed and fertilized with previously frozen sperm, and a normal infant can develop. On a larger scale, human embryos can be cryopreserved, later thawed, and implanted into the uterus for growth. Infants derived from this process are no different in growth or intelligence than those who came into being under natural conditions.

Background and History

In 1866, Italian physician Paolo Mantegazza suggested that before soldiers departed for the battlefield, they should leave behind frozen sperm. He also suggested collection of sperm for freezing just before a mortally wounded soldier would die. The first successful human pregnancy using frozen sperm occurred in 1953. Thirty years later, cryopreservation of oocytes was accomplished. In 1986, Australian physician Christopher Chen reported the world's first pregnancy using previously frozen oocytes. The rate of success of pregnancies using frozen oocytes, embryos, and fresh embryos are comparable.

The first cryonics organization, the Life Extension Society, was founded by Evan Cooper in 1963. As its title suggests, it aimed to practice life extension by freezing bodies to be thawed at a time when science could provide for longer life spans. Growth was slow over the next two years, and most of the people interested in the procedure were wealthy celebrities. The first person to be cryogenically frozen was James Bedford, a seventy-three-year-old psychologist. He was cryopreserved in 1967, and his body reportedly remained in good condition at Alcor Life Extension Foundation into the 2020s. By the late 1970s, six cryonics companies operated in the United States. However, the preservation and subsequent maintenance of bodies indefinitely proved to be too expensive for the general public, and many of the companies ceased operations in the 1980s. In the early twenty-first century, several companies in North America and Europe offered cryonics services. Demand for cryonics in the Asia Pacific region increased dramatically in the early 2020s, and Southern Cryonics opened the Southern Hemisphere's first cryonics facility in 2024.

How It Works

Embryo Cryopreservation. Embryo cryopreservation has evolved into a technology with a high success rate. Embryos can be frozen at the pronuclear stage (one cell) up to the blastocyst stage (five to seven days after fertilization; 75 to 100 cells). Freezing and thawing of embryos is overseen by embryologists who are assisted by laboratory technicians. The embryos are mixed with a cryoprotectant and placed in straws before freezing. This allows for vitrification during the freezing process. The scientific definition of vitrification is the conversion of a liquid to a glass-like solid, which is free of any ice-crystal formation. The straw is placed in a cooling chamber for freezing. After freezing, the straw is placed into a carefully labeled metal cane, which is lowered into a liquid nitrogen tank with other frozen embryos.

The thawing process involves warming the embryos to room temperature in thirty-five seconds. Over the next half hour, the embryos are incubated in decreasing concentrations of the cryoprotectant and increasing concentrations of water. These embryos are then transferred to a woman's uterus for growth. In the past, several embryos were transferred in the hope that at least one would survive. Existing technology has improved to the point that a single embryo has a high survival rate. The trend is to transfer a single embryo to prevent multiple births. Multiple births—even twins—have a much higher incidence of complications. Embryos stored for ten to twelve years have been thawed with the subsequent development of a live infant. Storage costs vary depending on the length of storage.

Sperm and Ovary Cryopreservation. For men planning to have a vasectomy or men with testicular cancer, sperm can be cryopreserved, which will allow the future fathering of children. In addition to the cryopreservation of embryos, women can have a portion of an ovary cryopreserved. This ovarian tissue can be thawed and transplanted at a later date. For women who must undergo chemotherapy for a malignancy, which can compromise their fertility, this is an extremely attractive option. The ovarian tissue contains thousands of eggs. Furthermore, this tissue will produce female hormones.

Comparison of Embryo Cryopreservation to Cryonics. Unlike the high success rate of human embryo transfer, cryopreservation of a fully formed individual is imperfect and theoretical. Embryos consist of many cells that can potentially develop into any tissue or organ. Embryos are preselected, and if available, only high-quality embryos are used. The embryos are in good health and well-oxygenated when frozen. The whole process, from freezing to storage and ultimate thawing, is orderly. 

An adult who wishes to be cryopreserved is usually of advanced age with multiple health problems, such as an advanced malignancy, severe heart disease, or Alzheimer's disease. The individual is also near death when the process begins. Often, as death approaches, multiple organ failure or stroke occurs. Unless the patient dies at a cryonics location and can be promptly instituted, a significant delay in the process can occur. Cryoprotectants must be infused and circulate throughout the body. With modern technology, despite the use of cryoprotectants, the blood vessels are damaged. Even in cases where only the brain is frozen, blood vessel damage occurs. Once frozen, no further damage will occur. However, a cryopreserved human is significantly damaged. When thawed, the individual must be restored to life as well as good physical and mental health.

Cryonics. According to the Alcor Life Extension Foundation, when a patient who has enrolled in a cryonics program becomes critically ill, cryonics personnel will be placed on standby. When the heart stops beating, the patient is placed in an ice-water bath, and cardiopulmonary resuscitation is begun. Intravenous lines are established to infuse cryoprotectants, medications, and anesthetics. The medications maintain blood pressure. The cooling and the anesthetic lower the oxygen consumption to protect the brain and vital organs. If the patient is in a hospital that does not allow cryonics procedures, the patient is transferred to another facility. Resuscitation and cooling are maintained during this process. The subsequent process includes surgically assessing the femoral (upper leg) arteries and veins, and the patient is placed on cardiopulmonary bypass with a portable heart-lung machine. External resuscitation is discontinued. In the heart-lung machine, a heat exchanger works to lower the body temperature to a few degrees above the freezing point of water (0 degrees Celsius), and then blood is replaced with a cryoprotectant.

The patient is then transferred to the cryonics facility (if not already there). Major blood vessels are accessed by thoracic surgery and attached to the perfusion circuit. Cryoprotectant is infused at nearly the freezing point of water for several minutes, which removes any residual blood. Then the cryoprotectant concentration is increased over a two-hour period to half the final target concentration. A rapid increase to the final concentration is then made. After cryoprotective perfusion, the patient is rapidly cooled under computer control by fans circulating nitrogen gas at a temperature of -125 degrees Celsius. The patient is then further cooled to -196 degrees Celsius over the next two weeks. The cost of the procedure and storage through the few available companies typically ranges into the tens of thousands or even hundreds of thousands of dollars. The fee often includes a basic cost at enrollment and usually requires an annual membership fee until death. Arrangements can be made to have these costs covered by life insurance.

Applications and Products

Cryoprotectants. A variety of cryoprotectants are available for cryopreservation of embryos and adults. Research is ongoing to improve these products. Conventional cryoprotectants in use include dimethyl sulfoxide (DMSO), ethylene glycol, glycerol, propylene glycol, propanediol (PROH), and sucrose. DMSO and glycerol have been used for decades by embryologists to cold-preserve embryos and sperm. Usually, a combination of ingredients is used because they have less toxicity and increased efficacy compared to a single substance. Cryoprotectants lower the freezing point of water. In addition, many cryoprotectants displace water molecules with hydrogen bonds in biological materials. This hydrogen bonding maintains proper protein and DNA function.

Cryonics Procedures. Cryonics companies employ specially designed resuscitation equipment to perform immediate cardiopulmonary resuscitation (CPR) immediately after death. Two such devices are the LUCAS Chest Compression System and Michigan Instruments' Thumper. These devices are powered by pressurized oxygen and restore blood flow much more efficiently than manual CPR. Later, a portable heart-lung machine is used to continue perfusion. After the instillation of cryoprotectants, transport, ranging from a few miles to thousands, is needed. Cryonics facilities contain an operating room with a heart-lung machine as well as a variety of specialized equipment for instilling cryoprotectants and controlled cooling. The use of the operating room is sporadic at best. Months and sometimes years transpire between patients. Nevertheless, it must be maintained in a standby status that can be made fully operational in a matter of hours. Technicians and medical personnel, including doctors and nurses, are obviously not part of the regular staff. They are alerted and assembled when the death of a cryonics applicant is imminent. In some cases, sudden death occurs, and the facility must have a system in place to obtain the necessary personnel on short notice.

Embryo Culture. Specially designed media and incubators are used for the culture of embryos. Research is ongoing to improve both the media and incubators. Around day five of development, the embryo will be in the blastocyst stage, and it must hatch out from its “shell,” a glycoprotein membrane called the zona pellucida, in order to implant in the uterus. If the embryo does not hatch, it cannot implant. Since the mid-1990s, assisted hatching has been performed to encourage embryos to come out. This is done by an embryologist, who makes a small hole in the zona of each embryo. The zona is not a living part of the embryo and making the hole does not harm the embryo. A laser beam is often used to make the hole.

Nanotechnology.Nanotechnology is focused on the manipulation of individual atoms or molecules with the ultimate goal of building or repairing any physical object, including human cells and biological tissue. Proponents of cryonics feel that, in the future, damaged tissue can be restored to a healthy state. This technology, if perfected, could repair damage from cryoprotectant toxicity, lack of oxygen, thermal stress (fracturing), ice-crystal formation in tissues that were not successfully vitrified, and reversal of the effects that caused the patient's death in the first place (heart attack, kidney failure, etc.). Advocates of freezing only the head feel that nanotechnology can regrow an entire body from the head. Theoretical revival scenarios describe repairs being accomplished via large numbers of devices or microscopic organisms. Repairs would be done at the molecular level before thawing.

Preservation of Mental Function and Memory. A successful cryonics outcome entails not only the restoration of a healthy body but also a healthy mind, which is fully functional with an intact memory. It is well known that if the brain is deprived of oxygen for more than four to six minutes, ischemic changes occur, which result in brain damage and brain death. Proponents of cryonics claim that these ischemic changes may be reversible with future technology. They also claim that personality, identity, and long-term memory persist for some time after death because they are stored in resilient cell structures and patterns within the brain. Thus, these features do not require continuous brain activity to survive. Another more radical cryonics concept is mind transfer. This entails a future technology that could scan the memory contents of a preserved brain.

Storage Facilities. Storage facilities for embryos are rooms containing tanks of liquid nitrogen, each containing many embryos. The tanks are, in essence, large thermoses. Cryonic storage tanks are obviously much larger. Some are designed to contain a single individual, while others can hold more than a dozen. Cryopreservation requires a constant source of liquid nitrogen because it evaporates, even in specially designed storage tanks. The tanks contain monitoring devices with alarms to indicate a drop in the nitrogen level. Some tanks have automated refilling devices attached. The nitrogen level in the air surrounding the tanks is also monitored. An increase in the nitrogen level would indicate leakage. The tanks are also inspected on a daily basis for any sign of leakage.

Careers and Course Work

Individuals interested in a career in cryopreservation and cryogenics may find opportunities in many fields, including nuclear physics, astrophysics, materials research, cryosurgery, cryobiology, cryogenic treatment of metals, and more. Cryogenicists require education according to the needs of their chosen specialty area and hands-on experience from internships or fellowships. Some individuals enter the field with a background in electrical or chemical engineering, physics, or materials science. Columbia, Cornell, and Boston Universities, among others, offer education opportunities in cryogenics, and the Cryogenic Society of America offers short courses and webinars.

Social Context and Future Prospects

The field of cryonics is speculative and controversial on scientific, sociological, and religious grounds. Proponents claim that it provides a possibility of a future existence to the finality of death. They suggest the possibility of immortality if revival is successful as well as the associated benefits that postponing or avoiding dying would bring. They tout that the cost of the procedure pales in comparison to the possible benefits. One of the arguments against the procedure is that it would change the concept of death. If life is restored at some time in the future, likely no friends or family would be left alive (unless they also were preserved), leaving them in an unfamilar world. Furthermore, religious beliefs often include a spiritual afterlife, which would potentially be disrupted by the cryopreservation process.

Opponents state that the funds spent for cryopreservation could better be spent on worthwhile causes such as charities or providing funds for education of family members. They also claim that cryonics could lead to premature euthanasia to maximize the chances for revival. In fact, Alcor became involved in a lawsuit involving that topic. In 1987, an eighty-three-year-old woman who had opted for cryonics developed pneumonia after several years of poor health. Alcor personnel deemed that death was imminent and transferred the woman to their facility. She subsequently underwent a "neuro," or head preservation. After the local coroner received a headless body, he demanded the head, which Alcor refused. The coroner launched an investigation and accused Alcor of murder. The case was settled out of court in the company's favor in 1991. Other cases have been brought to court by family members of individuals who have chosen to undergo freezing to object to their loved ones' decisions. For example, a Colorado judge upheld an early 2020s contract a woman named Mary Robbins signed with Alcor despite protests from her children.

Another concern is equipment failure. Thousands of human eggs and embryos were lost in 2018 in California when the tank they were in failed. After three years of litigation, a jury awarded five of the patients affected millions in damages. The wide scientific acceptance of cryonics requires both cryopreservation and successful revival. Some proponents suggest this can be accomplished with animal experimentation. For example, dogs that are placed in a pound and scheduled for euthanasia after the expiration of the adoption period could instead become subjects for cryonics experimentation.

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