On January 12th, 1967, James Bedford passed away. However, he had a plan to cheat death: he was the first person to be cryogenically frozen, with the dream of cryonics promising to preserve his body until a future when humanity could cure any illness and reverse death. But to revive people in the future, we need to properly preserve them in the present. Is it currently possible to freeze a human, preserve them indefinitely, and then safely thaw them out?
To understand the hurdles of human cryopreservation, we need to look to the scientific field of cryobiology. This discipline studies the effects of low temperatures on various living systems, and at temperatures below -130 degrees Celsius, human cellular activity grinds to a halt. However, freezing an organism without damaging the body is difficult, as water outside and inside the cell hardens into damaging ice crystals, and without the correct concentration of water, the chemical solutes become increasingly concentrated in a destructive process known as osmotic shock.
Many animals have evolved to survive extreme conditions, such as cold-tolerant fish synthesizing antifreeze proteins, or freeze-tolerant frogs using protective agents to survive when up to 70% of their body water is trapped as ice. By researching these adaptations, scientists have developed remarkable preservation technologies, some of which are already employed in medicine.
Researchers are still trying to improve cryopreservation technology to better manage the ice problem, with an approach called vitrification. This technique uses chemicals known as cryoprotectant agents (CPA) to prevent ice from forming, and allows researchers to store living systems in a glassy state with reduced molecular activity and no damaging ice. However, these chemicals can be toxic in the high quantities required for large scale vitrification, and even with them, preventing ice formation requires rapid cooling that lowers temperatures uniformly throughout the material. To date, researchers have been able to vitrify and partially recover small structures like blood vessels, heart valves, and corneas, but none of these are anywhere near the size and complexity of a whole human being. The unfortunate reality is that cryopreservation techniques as they currently stand are not scientifically sound and can cause significant damage to the body’s cells, tissues, and organs. While some might suggest that this damage may be reversible in the future, there are many ethical, legal, and social concerns that need to be addressed before this technology can be deemed beneficial. As a result, the hope of cryonics remains in limbo.