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While cryopreservation using fixatives is available, how many times more likely will someone be to be revived by 2200 if they are cryopreserved using fixatives than without?

The Large Mammal BPF Prize was won in 2018 by a technique called Aldehyde-Stabilized Cryopreservation. ASC uses glutaraldehyde to crosslink the brain's proteins in place; this removes the possibility of restoration of biological function, but protects the tissue from decay due to autolysis or putrefaction. Glutaraldehyde fixation is currently used in neuroscience to prepare brain tissue for electron microscopic and immunofluorescent examination.

Alcor, a major cryonics provider, is skeptical of fixatives and does not currently offer ASC. Ralph Merkle, writing for Alcor, writes:

Rather obviously, if you want to cryopreserve someone you’d rather not perfuse them with glutaraldehyde. It’s a fixative. On the other hand, if you don’t use glutaraldehyde, then you’re going to get dehydration and shrinkage, which means you won’t get the pretty pictures that neuroscientists like.

So, what’s your preference? Better pictures, or better biological viability? The neuroscientists want the pictures. Alcor has traditionally worked to achieve better biological viability.

[...] The cryobiological experts who advise Alcor favor the use of Alcor’s current protocol (or we would have changed it).

The Brain Preservation Foundation, which awarded the $80,000 prize for ASC, is more hopeful, claiming that these better pictures make the brain more suitable for eventual resurrection via scanning and uploading.

What will the value (% of people cryopreserved while fixatives are available, who are cryopreserved using fixatives, who are revived) / (% of people cryopreserved while fixatives are available, who are cryopreserved without using fixatives, who are revived) be at the start of 2200?

This counts only the people who are cryopreserved while fixatives are available, so that the question measures only the effect from using fixatives, and not general improvement in cryonics between 1967 and whenever fixatives become available, and from later techniques which would supersede fixatives.

"Available" means that a cryonics organisation officially offers cryopreservation using fixatives to its members.

"Revival" means that the person would be able to meet the standard described in this question; either through conducting that specific test, or by some measurement that is equivalent such as official statistics on the health of revived patients.

If nobody is revived from cryopreservation before 2200, or nobody is cryopreserved using fixatives, then this resolves ambiguously. If the only people revived are those who were preserved using fixatives, then this resolves above the upper end of the scale.


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