The Frozen Dream: Challenges in Human Cryopreservation

On January 12th, 1967, James Bedford passed away, but he had a plan to defy death. Bedford became the first person to undergo cryogenic freezing, a process that promised to preserve his body until a future time when humanity could conquer all illnesses and reverse death itself.

This is the concept of cryonics. However, there's a crucial catch: to revive individuals in the future, they must be adequately preserved in the present. So, is it currently possible to freeze and preserve a human indefinitely, only to safely thaw them out later? To understand the challenges of human cryopreservation, we must step away from the theoretical realm of cryonics and delve into the scientific field of cryobiology.

Cryobiology is dedicated to studying the effects of low temperatures on living systems. It's true that reducing an organism's temperature also diminishes its cellular function. For instance, at temperatures below -130 degrees Celsius, human cellular activity ceases. Theoretically, if an entire human body could be brought below this temperature, it could be preserved indefinitely. The difficulty lies in achieving this without causing damage to the body.

For instance, let's consider freezing a single red blood cell. Under normal conditions, it exists at a temperature of 37 degrees Celsius in a solution of water and chemical solutes. However, when the temperature drops below freezing, water inside and outside the cell forms damaging ice crystals. Chemical solutes cannot dissolve without the proper concentration of water. As the water freezes, these solutes become increasingly concentrated, leading to a destructive process known as osmotic shock. Left unchecked, these factors guarantee the destruction of our red blood cell before reaching -130 degrees.

Not all cells are as fragile, and various animals have evolved to survive extreme conditions. Some cold-tolerant fish produce antifreeze proteins to prevent ice formation at sub-zero temperatures. Freeze-tolerant frogs employ protective agents to survive when a significant portion of their body water is trapped as ice. However, it is unlikely that any single creature holds the secret to human cryopreservation.

By studying these adaptations, scientists have developed remarkable preservation technologies that are already utilized in medicine. Nevertheless, researchers continue to refine cryopreservation technology to address the ice problem. Many cryobiologists are exploring vitrification, an approach that employs cryoprotectant agents (CPAs) to prevent ice formation. Some of these agents are derived from natural compounds, while others are specifically designed based on cryobiology principles. These chemicals enable researchers to store living systems in a glassy state with reduced molecular activity and no damaging ice.

Vitrification holds immense promise for cryonics and could revolutionize organ and tissue preservation for medical purposes. However, achieving successful vitrification is extraordinarily challenging. CPAs can be toxic in the high quantities required for large-scale vitrification. Moreover, preventing ice formation necessitates rapid cooling that uniformly lowers temperatures throughout the material. While this is relatively feasible for single cells or small tissue samples, it becomes increasingly difficult as complexity and water content increase.

Even if complex living material could be successfully vitrified, the process of uniformly warming the tissue to prevent ice formation or cracks poses another significant hurdle. So far, researchers have managed to vitrify and partially recover small structures like blood vessels, heart valves, and corneas. However, these are far from the size and complexity of a whole human being.

Considering the current limitations, cryopreservation techniques as practiced today offer false hope to patients. They are unscientific and cause irreparable damage to cells, tissues, and organs. While some enthusiasts argue that this damage may be reversible in the future, even if cryonic preservation could revive individuals, a myriad of ethical, legal, and social implications cast doubts on its overall benefits.

For now, the dream of cryonics remains frozen, awaiting scientific breakthroughs and addressing the substantial challenges that lie ahead.

Henrik Leandro