While the key to reanimation eludes scientists and entrepreneurs alike, the cryopreservation process is fairly simple. After clinical death, bodies are cooled and an anticoagulant is injected to prevent the blood from clotting. Then a procedure called "perfusion" is performed -- preferably within hours of death -- to remove blood from the body; it is replaced with a freeze-resistant chemical that prevents ice crystals forming that would destroy tissue when thawed.
'Definitely Not Science'
Cryonics has never made it into the mainstream, and many scientists balk at the lack of evidence underpinning it and, more broadly, transhumanism.