Cryptobiosis

[noexpert]

I recently discovered cryptobiosis when reading about its utilization in Tardigrades (water bears). I looked for other forums that may discuss this but I couldnt't find any. Anyway, it seems like it could prove to be of great usefulness if we could utilize this. So I was wondering if there are, or have been any, attempts to achieve this in some way in humans or other mammals? Is it even possible. Maybe understanding how it is that water bears and other organisms achieve this could help to understand how it could be done in other species.

[noexpert]

Any thoughts??

[C1ay]

I haven't studied it enough to effectively discuss it. I think certain cellular properties would be required to support it. I do know something similar is done in Russian medicine where one's metabolism is brought to a standstill by supercooling the brain for procedures like open heart surgery. It can only be done for a short duration though, less than an hour I think. Like you, I couldn't find much discussion about it on the web.

[CraigD]

I recently discovered cryptobiosis when reading about its utilization in Tardigrades (water bears)

…

So I was wondering if there are, or have been any, attempts to achieve this in some way in humans or other mammals?

Cryptobiosis is (I just learned – wasn’t familiar with the term ‘til now) a more technically precise, catch-all term for what’s commonly known as “suspended animation”.

 

There’s certainly been research, and substantial commercial interest and development, in one form of cryptobiosis: cryobiosis, usually called cryonics, where the severed head or entire body of a human is “frozen” shortly before or after death (typically after steps to prevent the formation of tissue-damaging ice formation) in the hope that future developments in the technology will all then to someday be revived.

 

Is it even possible.

The People who have chosen to be cryopreserved – usually at considerable cost to their estates – are certainly hoping so, as are medical researchers who see the potential of such technology to preserve accident victims in the field until they can reach treatment facilities.

 

Recent experiments with cyopreserving and reviving dogs and pigs after periods of a few hours have been successful (see: this 2005 and this 2006 news article)

 

Maybe understanding how it is that water bears and other organisms achieve this could help to understand how it could be done in other species.

Water bears (Tardigrades) suspend their metabolism by via the anhydrobiosis, or desiccation, form of cryptobiosis. We know that cells in species like humans are irreparably damaged by desiccation, so unless some sort of additive to prevent this, and a way to deliver it to enough cells, can be invented, this approach doesn’t seem promising.

[noexpert]

I was thinking less along the lines of cryogenic freezing, and more in the manner that terdigrades do it. So really I am curious as to what body functions allow them to hibernate in the way they do, since they obviously dont freeze themselves. So more into one of the other four types of cryptobiosis: Anhydrobiosis, Anoxybiosis, Chemibiosis, or Osmobiosis.

[CraigD]

I was thinking less along the lines of cryogenic freezing, and more in the manner that terdigrades do it. So really I am curious as to what body functions allow them to hibernate in the way they do, since they obviously dont freeze themselves

As I mentioned, tardigrades nearly stop (reduce to on the order of 1/10000th) their metabolism via Anhydrobiosis, AKA dessication, or drying out (to on the order of 1/100 their usual amount of water).

 

Empirically, Anhydrobiosis occurs in small animals with simple body forms typified by insects - those in the Ecdysozoa superphylum - and many plants and single celled organism. There's a reasonable chance that if you take such an organism, dehydrate it, then days later, rehydrate it, it'll resume fairly normal metabolism - ie: come back to life. Take a bigger animal with a more complicated body plan - that is, one with more specialized, more fragile tissues, especially nervous systems - and try this procedure, and it'll kill it.

 

It seems to me this is due to 2 main factors:

1. Mechanical - The bigger animal has a much larger number of cells to surface area ratio, so both takes longer to dehydrate and rehydrate, and de/rehydrates "unevenly". Cells contract when they dehydrate, so this results in much more mechanical stress on the animal's tissues, damaging them too much for it to survive.
   
2. Specialization - The more complicated animal has specialize tissues that are both easily damaged, and critical to their living, that are irreparably damaged by dehydration and rehydration.
   

Intuitively, imagine (or, better yet, actually do) drying out a live tardigrade, and looking at it under a microscope. You see a shrunken tardigrade. Now imagine drying out a live human (do NOT actually do this!). You see first a distressed, then a dead, then a mummified human.

 

Anhydrobiosis doesn't scale well.

[noexpert]

what about the others? We have found that it is possible (at least temporarily) via cryogenic freezing, so I am just thinking maybe it is reasonable to say that we should explore other methods. If we just think of the bigger organism as many smaller parts, and simultaneously treated as though, is it not possible to stop and restart each of the parts? My point is, that the possibilities should be further explored, especially with the possible advantages.

[C1ay]

My point is, that the possibilities should be further explored, especially with the possible advantages.

It is being heavily explored. There is a lot of money spent by rich estates to use cryogenic freezing to preserve the owners that have passed away in hopes that someday the disease that killed them will be curable and that medicine will have evolved to the point where they could be revived.

 

There is also a great deal of research in finding ways to induce some kind of suspended animation for space travel since it would literally take generations just to travel our own solar system. Interstellar travel would make it more of a necessity.

 

There is also some research on using it for trauma victims, like wounded soldiers, to prolong their life until they can undergo the necessary treatment to save their lives. I'd imagine the list goes on and on...

[noexpert]

Do you know of a site where I can do some research on these types of studies?

[C1ay]

Do you know of a site where I can do some research on these types of studies?

I suspect most of it is privately funded and not available for public view. This has the potential to be very valuable and investors are going to want to keep their progress private.