On January 12th, 1967, James Bedford passed away. But— he had a plan to cheat death. Bedford was the first person to be cryogenically frozen. This process promised to preserve his body until a theoretical future when humanity could cure any illness, and essentially, reverse death. This is the dream of cryonics. But here’s the catch: to revive people in the future, we need to properly preserve them in the present. So, 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 leave the theoretical realm of cryonics, and turn to the scientific field of cryobiology. This discipline studies the effects of low temperatures on various living systems, and it is true that decreasing an organism’s temperature also decreases its cellular function. For example, at temperatures below -130 degrees Celsius, human cellular activity grinds to a halt. So if you could bring an entire human body below that temperature, theoretically you could preserve it indefinitely. The hard part is doing this without damaging the body. For example, let’s try to freeze a single red blood cell. It typically sits at a temperature of 37 degrees Celsius in a solution of water and substances known as chemical solutes, which dissolve under certain conditions. But once the temperature drops below freezing, water outside and inside the cell hardens into damaging ice crystals. Without the correct concentration of water, the chemical solutes are unable to dissolve. And as the water freezes, they become increasingly concentrated in a destructive process known as osmotic shock. Without any intervention, these factors are guaranteed to destroy our red blood cell before it reaches -130 degrees. Not all cells are this fragile, and many animals have evolved to survive extreme conditions. Some cold-tolerant fish synthesize antifreeze proteins to prevent ice formation at sub-zero temperatures. And freeze-tolerant frogs use protective agents to survive when up to 70% of their body water is trapped as ice. It’s unlikely that any one creature holds the secret to human cryopreservation. But by researching these adaptations, scientists have developed remarkable preservation technologies, some of which are already employed in medicine. However, researchers are still trying to improve cryopreservation technology to better manage the ice problem. Many cryobiologists are trying to solve this issue with an approach called vitrification. This technique uses chemicals known as cryoprotectant agents (CPA) to prevent ice from forming. Some of these have been adapted from compounds in nature, while others have been designed to take advantage of cryobiology’s guiding principles. But in practice, these chemicals allow researchers to store living systems in a glassy state with reduced molecular activity and no damaging ice. Vitrification is ideal for cryonics, and would help preserve organs and other tissues for medical procedures. But it’s incredibly difficult to achieve. CPAs can be toxic in the high quantities required for large scale vitrification. And even with these chemicals, preventing ice formation requires rapid cooling that lowers temperatures uniformly throughout the material. That’s relatively easy when vitrifying single cells or small pieces of tissue. But as the material becomes more complex and contains larger quantities of water, staying ahead of ice formation gets challenging. And even if we could successfully vitrify complex living material, we’d only be halfway to using it. Vitrified tissue also needs to be uniformly warmed to prevent the formation of ice, or worse, cracks. 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. So if it’s not currently possible to cryopreserve a person, what does this mean for Bedford and his frozen peers? The sad truth is that current cryonic preservation techniques only offer their patients false hope. As practiced, they’re both unscientific and deeply destructive, irreparably damaging the body’s cells, tissues, and organs. Some devotees might argue that, like death and disease, this damage may be reversible one day. Even if scientists could revive people through cryonic preservation, there’s a whole suite of ethical, legal, and social implications which cast doubts on the technology’s overall benefits. But for now, the dream of cryonics is still on ice.
