How Does Cryonics Work? A Step-by-Step Guide
Basics
Most people have a vague sense that cryonics involves freezing someone who has died, but the actual process is far more careful — and far more interesting — than that. Here's a clear, step-by-step look at what happens from the moment of legal death to long-term storage.
Step 1: Legal Death Is Declared
Cryonics begins only after a physician declares legal death. This is an important distinction: cryonics is not a medical procedure performed on living people, and it doesn't interfere with end-of-life care. Once legal death is pronounced, the clock starts. The sooner the preservation team can begin, the better — every minute matters for preserving the quality of the brain's structure.
Step 2: Immediate Stabilization
A standby team — ideally positioned nearby in anticipation — begins stabilization as quickly as possible. This involves packing the body in ice to slow biological degradation, performing mechanical CPR to maintain circulation, and administering medications that protect cells and reduce swelling. The goal at this stage is to buy time, keeping the brain's structures as intact as possible while preparing for the actual preservation procedure.
Step 3: Replacing Blood with Cryoprotectant
This is where cryonics diverges sharply from simple freezing. The blood is gradually replaced with a cryoprotectant solution — a carefully formulated mixture that prevents ice crystals from forming inside cells. Ice crystals are the main mechanical threat in any kind of freezing: they puncture cell membranes and shred tissue structure. By replacing blood with cryoprotectant, the preservation team eliminates that risk. The tissue doesn't freeze in the damaging sense — it vitrifies, transitioning into a stable, glass-like state.
Step 4: Gradual Cooling
The brain (or body, depending on the provider) is then cooled gradually and precisely down to -196°C, the temperature of liquid nitrogen. Rapid or uncontrolled cooling can cause cracking and other structural damage, so the process is carefully managed. At -196°C, all biological and chemical processes essentially halt. The tissue is in a state of suspended animation at the molecular level.
Step 5: Long-Term Storage in a Dewar
Once cooled, the preserved brain is stored in a dewar — a large, thermally insulated vessel that maintains liquid nitrogen temperatures. Dewars are passive systems: they don't require electricity to keep things cold, which makes them resilient to power outages and other disruptions. Storage can, in principle, continue indefinitely.
Saka Cryo's Approach: ASC
Saka Cryo uses Aldehyde-Stabilized Cryopreservation (ASC) rather than traditional vitrification alone. ASC begins with a chemical fixation step using glutaraldehyde, which rapidly and thoroughly stabilizes the brain's neural structures. This would be a step 2.5 in the above procedure order. After fixation, the tissue is biologically inert — it no longer degrades — and can then be vitrified and cooled for long-term storage.
One significant advantage of ASC is resilience. Traditional vitrification must stay below -130°C continuously; if temperatures rise, damage can occur. Because ASC-fixed tissue is chemically stabilized, it can safely reach room temperature and return to frozen storage without compromising the preservation. That kind of robustness matters enormously for long-term storage across an uncertain future.
The whole process — from stabilization to final storage — reflects decades of refinement. It's not perfect, and no one claims it is. But it's far more rigorous than most people expect.
