By Kia Popat

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Cryonics is the preservation of people, at a temperature of around -196°C, who cannot survive using medicine we have currently. This is done in the hope that restoration to full health in the future will be possible. However, at the moment, cryonics is often criticised by scientists, and is not part of normal medical practice, as cryopreservation is not reversible with current technology.

When a person has been declared legally dead, the process of cryonic preservation can begin. The person’s blood must continue to pump around their body, particularly to the brain, whilst the body is packed in ice and injected with heparin, an anticoagulant, which ensures that the blood does not clot. When the person arrives at the cryonics facility, the actual freezing process begins. The body cannot just be put into a vat of liquid nitrogen, or the water inside their cells would freeze, expand, and shatter. The cryonics team has to remove all the water from your cells and replace it with a glycerol-based cryoprotectant, which is an antifreeze for humans. This process is called vitrification, which cools the body to extremely low temperatures without freezing it and puts the cells into a state of ‘suspended animation’, somewhat similar to hibernation. The body is then cooled on a bed of dry ice until it reaches a temperature below -130 degrees C, and finally, the body is inserted into a metal tank filled with liquid nitrogen. The body is stored upside-down so that if there was ever a leak in the tank, the brain would stay in the liquid and survive.

Enthusiasts, that believe that cryonic preservation will work, think that damage to the brain is reversed by preventing oxygen levels from dropping too low and that cooling a body to such low temperatures slows the chemical processes in cells and tissues significantly enough to ensure that the body is not decomposed any further. They also believe that the inevitable damage to the body by the freezing process can be healed by the use of nanotechnology, in the future.

There is no definite possibility that a person who is cryonically preserved will be able to be brought back to life. Not only is it difficult to limit the damage from cryoprotectants, but it is also hard to safely remove them from the body so that they can be replaced with blood. Also, cooling the body down to such a low temperature makes it very brittle, and susceptible to shattering during the warming process, as a result of thermal stress. The brain itself, particularly the neurons inside it, are extremely sensitive to heating and cooling, so the cryonic process could also ruin them. Furthermore, as people can only be cryonically preserved after death, the bodies will likely be damaged by ageing and illness. Cryopreservation disrupts all the proteins and molecules that make up the membranes of a cell, meaning that a very sophisticated version of nanotechnology would be needed to restore people to life. A greater understanding of the brain would also be needed before reversing the process, in order to know which connections are crucial to repair, and which ones could be lost. If all of these issues can be solved, there is no reason why cryonic preservation would not preserve a person and their memories, although it would likely be very disorientating and confusing to a person when they wake up many years in the future.

Cryonics is very expensive and can cost up to $150,000 to have the body preserved. For those with the money to do so, there is even the option of having your pets cryopreserved. However, another option is available for those with less money. Neurosuspension allows people to have their brain preserved, with the hope that future technology will allow the rest of the body to be cloned or regenerated.