CAN YOU FREEZE YOUR BODY AND COME BACK TO LIFE?

On January 12, 1967, James Bedford passed away. But he had a plan to cheat death. Bedford was the first person to be cryogenically frozen. The procedure promised to preserve his body until a theoretical future in which humanity could cure any disease and essentially reverse death. This is the dream of cryonics.

However, there is a catch: in order to resurrect people in the future, we must properly preserve them in the present. So is it currently possible to freeze a human being, preserve them indefinitely, and then thaw them safely? To understand the hurdles of human cryopreservation, we must leave the theoretical realm of cryonics and turn to the scientific realm of cryobiology. This discipline studies the effects of low temperatures on various living systems, and it is true that lowering the temperature of an organism also limits its cellular functions. For example, at temperatures below -130 degrees Celsius, human cellular activity comes to a halt. So if you could bring an entire human body below that temperature, you could theoretically preserve it indefinitely. The difficulty is doing this without damaging the body. For example, one could try to freeze a single red blood cell. Normally, at a temperature of 37 degrees Celsius, it is in a solution of water and so-called chemical solutes, which dissolve under certain conditions. However, once the temperature drops below freezing, the water hardens outside and inside the cell to form harmful ice crystals. Without the right concentration of water, the chemical solvents cannot dissolve. And as the water freezes, they become more concentrated in a destructive process called osmotic shock.

Without any intervention, these factors are guaranteed to destroy our red blood cell before it reaches -130 degrees. Not all cells are so sensitive, and many animals have evolved to survive extreme conditions. Some cold-tolerant fish synthesize antifreeze proteins to prevent ice formation in subzero temperatures. And freeze-tolerant frogs use protective compounds to survive when up to 70% of their body water is trapped as ice. It's unlikely that a single creature holds the secret to human cryopreservation. But by studying these adaptations, scientists have developed remarkable preservation technologies, some of which are already being used in medicine.

However, researchers are still trying to improve cryopreservation technology to get a better handle on the ice problem. Many cryobiologists are trying to solve this problem with an approach called vitrification. This technique uses chemicals that act as cryoprotectants (CPA) to prevent ice formation. Some of these chemicals have been adapted from compounds found in nature, while others have been developed to take advantage of the guiding principles of cryobiology. In practice, these chemicals allow researchers to store living systems in a glassy state with reduced molecular activity and without harmful ice.

Vitrification is ideal for cryonics and would help preserve organs and other tissues for medical procedures. But it is incredibly difficult to achieve. CPAs can be toxic in the large quantities required for large-scale vitrification. And even with these chemicals, preventing ice formation requires rapid cooling that lowers temperatures uniformly throughout the material. For vitrification of single cells or small pieces of tissue, this is relatively easy. But as the material becomes more complex and contains more water, it becomes more difficult to forestall ice formation. And even if we succeeded in vitrifying complex living material, we would only be halfway to using it. Vitrified tissue also needs to be heated uniformly to prevent ice or, worse, cracks from forming. So far, researchers have succeeded in vitrifying and partially restoring small structures such as blood vessels, heart valves and corneas. But none of these structures are anywhere near the size or complexity of an entire human being. So if it’s not currently possible to cryopreserve a human, what does that mean for Bedford and his frozen colleagues? The sad truth is that current cryopreservation techniques only give patients false hope. As practiced, they are both unscientific and deeply destructive, irreparably damaging the body’s cells, tissues and organs. Some adherents might argue that this damage, like death and disease, could one day be reversible.

Even if scientists succeeded in reviving people through cryonic preservation, there would be a host of ethical, legal and social implications that call into question the overall benefits of the technology. But for now, the dream of cryonics is on hold.