Extreme Cold and Cellular Damage
Alcor stresses that their procedures for freezing bodies are quite similar to those used by organ transplantation surgeons to protect human organs when they are moved from one person to another. After an organ such as a kidney is taken from one person, transplant technicians cool down the organ in order to slow down the biological processes, and decay, of the tissues while it is being transported to the organ recipient.
In addition, in order to prevent ice crystals from forming in the organ tissues -- which would damage the organ itself -- transplant technicians perfuse the organs with special fluids that do not form crystals when close to freezing. In the same way, Alcor replaces the blood of the recently deceased patient with these cryopreservant chemicals in order to minimize the damage to tissues.