Cryosleep technology has its roots in experiments dating back to the 1960s. Some of the earliest attempts to induce a state of suspended animation through cryogenic freezing involved scientists like Dr. James Bedford. In 1967, Bedford successfully froze and revived a dog using a circulating liquid with antifreeze properties. However, the animal experienced brain damage and other complications. Throughout the late 1960s and 1970s, various teams experimented with freezing small animals with limited success. While some survived the freezing and thawing process intact, many suffered neurological or cellular damage that proved fatal.

It was not until the 1980s that scientists began achieving more promising results with larger animals. A team at the University of Pittsburgh led by Dr. Samuel Tarelnick used a technique known as vitrification to freeze dogs without forming ice crystals. Vitrification circumvents the dangers of ice crystallization at the cellular level by turning tissues directly into a glass-like state through ultra-rapid freezing. The dogs survived without apparent harm. Testing continued through the 1990s involving pigs, monkeys, and other larger test subjects with vitrification techniques. By the 2000s, scientists could reliably freeze and revive larger mammals intact and healthy.

Developing Vitrification Technologies for Human Cryosleep

While remarkable progress has been made freezing and reviving larger animals, major challenges remain to applying Cryosleep technology safely to humans. A key focus of ongoing research involves further developing vitrification agents and protocols that can safely bring the entire human body, including the brain, down to cryogenic temperatures without damage. Several compounds show promise as blood substitutes and cryoprotectants, including various sugars and polymers, but require more testing. Technical challenges also exist in developing systems capable of achieving the necessary ultra-fast cooling and rewarming rates across the entire human body uniformly and without freezing of tissues.

Beyond technical challenges, gaining approval for human testing also poses regulatory difficulties. No regulatory body has approved trials involving human cryopreservation for reasons of safety and medical ethics. Researchers must demonstrate techniques can reliably resuscitate humans without harm before regulators will approve its testing on terminally ill patients. Continuous life support also poses issues during long-term, underground storage that would be needed to preserve patients until future medical advances could potentially revive them.