How come it’s possible to cryopreserve things like sperm and very young embryos, and to later thaw them out so that they can live, but it’s impossible to do that for older humans or anything that consists of more than a few cells?

Question

I mean, sure, there is mummification and and some bodies being naturally preserved due to coldness or dryness, but I’m talking more about the idea of cryonics- the idea that you could stop a biological organism’s entire metabolism in some kind of suspended animation and then later thaw them out and be able to continue living. Most of this is just science fiction though and greatly exaggerated. All of the people who have gotten their bodies cryopreserved as adults are people who have died and it’s essentially just mummification instead of suspended animation.

In: Biology

Answer 1

The top comment has some misconceptions. Cryonics companies do exist and they now use vitrification, rather than freezing, which avoids ice formation.

The reasons animals or humans can’t currently be revived from _that_ are that the vitrification mixtures that are used are themselves toxic, and there is of course damage that occurs. The hope is to preserve the structure (esp. of the brain) for future technology to potentially reconstruct – not to keep tissues or organs in a near-functional state.

The core idea is preventing “info-death” – there should be enough information that can be used to restore the brain in theory. Whether that is accomplished is debatable. Some people clearly think the cost/benefit analysis is favourable, and I am inclined to think that viewpoint makes sense.

Small bits of tissue like blood vessels have been successfully vitrified and revived, but nothing very large. If it’s at all possible to revive current cryonically preserved people and animals, it will probably require far more advanced technology.