No one wants to die, especially not prematurely. Unfortunately, accidents happen, people get sick, and there is no avoiding that. Because of this, people are continually trying to discover a way to prolong life or at least preserve it until there is a procedure that can accomplish this. This is where cryogenics come into play. At this point, your only available option is to freeze your body and hope science advances quickly enough to bring you back or cure you.
At least this is what a small but growing group of people thinks. Even if this never happens for humans, people are still going to try this only because nature has already shown that this is possible. Animals like reptiles, amphibians, worms, and insects have demonstrated previously that cryopreservation is possible. During a study on nematode worms, the worms were able to recognize a smell they had been trained for even after being frozen. Another instance where cryopreservation worked was in wood frogs. They are frozen into blocks of solid ice during winter, but when spring rolls around, they can jump around without any issues. Unfortunately, this process does not seem to work as well for humans. Every time human skin has been frozen it displayed signs of significant damage after thawing.
Cryobiology is currently working on ways to eliminate this type of damage as soon as possible. The issue is that scientists still do not understand this kind of damage on a cellular level. Any innovation needs to improve two aspects; the first one is the way the body is preserved during freezing, and the other is to reduce the damage induced by thawing. The main thing that needs to be developed is a way to transition into vitrification seamlessly, and that means the process is done by rapid cooling and not by freezing. Freezing creates ice spots that damage skin cells.
For now, scientists have tried using sugars and starches to change viscosity. Also, chemical compounds like ethylene glycol and propanediol are great at preventing ice formation on an intracellular level. Re-crystallization can also be controlled by using anti-freeze proteins during the thawing process.
Frozen tissue is something that needs to be accounted for as well. The tissue is biologically stable, but frozen structures might have a physical disruption like a hairline crack. These cracks then cause a plethora of problems during the thawing process. This can also set-off epigenetic reprogramming which then has adverse effects on our genes.
Even reviving the whole body has its set of problems, the main one being the homogeneous functioning of all organs. When a body is revived, it is vital that all its organs start working at the same time. This, fortunately, is not such a big issue because cooling has shown the ability to mitigate trauma. An excellent example of this is drowning victims who upon revival seem to have been protected by the cold water that surrounded them.
Finally, two huge hurdles are yet to be overcome. The first one is the process of freezing a brain in such a way that it retains all of its functions. All animal studies regarding this date from the 1970s, so that data is not useful. Without massive advancement in this field, cryopreservation is not going to be possible.
The second one is finding a way to revert the damage on the frozen body. This time we are speaking about the damage that led to the death of the person, not the damage caused by the freezing process.
The key for both of these probably lies in nanotechnology and the use of tiny molecular machines. This seemed like science fiction not too long ago, but rapid advancements meant that this technology might just give researchers the necessary tools to make cryopreservation and subsequent revival a possibility.