Re: CRYOprotectants: Replies to Sandberg

Anders Sandberg (
28 Dec 1997 20:11:11 +0100

Twink <> writes:

> Note: cp = cryoprotectant
> At 03:32 PM 12/16/97 +0100, Anders Sandberg <> wrote:
> >> More than one cp?
> >> Is a cp "cocktail" better than one cp?
> >
> >The problem is the combinatoric explosion of the search space.
> Agreed, which is why it would be nice to have a model of what is going on
> here so that one could use something like computer simulations with a GA
> to narrow the search.

Yes, that would be helpful. But simulating the interactions between
arbitrary cps and a more or less living tissue is a *heavy*
problem. Of course, some approximations could be done (such as a
simple phenomenological model of crystal formation depending on some
properties of the cps), and then more detailled studies could be done
with the successful combinations, but I guess there will be a lot of
both beneficial and problematic interactions that are very hard to
deal with using general rules (cp X forms a complex with cp Y that
limits perfusion, cp X, Y and Z appears to be very bad in simulations
but due to serpendipity they interact with some body-chemicals to form
a very good cryoprotectant solution).

> >> Perhaps different cps should be used for different
> >> tissues?
> >
> >Problem: how do you get them there?
> It might be possible that some cps flow into tissue at different rates, in
> which case, a cp cocktail might be made which can be administered
> in the same way current ones are.

One could also look at cps or additives that bind more or less
strongly to certain tissues, "opening" or "closing" them for each
other. Sounds complex but interesting (maybe something that opens the
blood brain barrier first?)

> Perhaps a multistage process might be used in which blood is removed
> and cps are injected into the tissues rather than through the main
> circulatory system.

It is hard to get better access than the circulatory system - it is a
spacefilling fractal.

> (Stanislaw Lem's novel _Fiasco_ has cryonic suspension units inside
> walkers on Titan, so that if the pilots of the walker wind up in a pinch,
> they can suspend themselves. Early in the novel, there is no way to
> revive people, but later on a means develops and one of the
> preserved persons is revived.)

Yes, it is a quite reasonable idea with emergency vitrification. A bit
like an airbag...

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y