This paper seems to have been eagerly anticipated by some in the cryonics community. At the end of the abstract they describe this paper as the first evidence that ultrastructural integrity is preserved in vitrification without the need for prior aldehyde fixation. OK, so now there is one paper that shows that cryopreservation is possible. Science is not based on individual papers. I want to be very clear about what this does not mean. It does not mean the quality is as good as with aldehyde fixation. I can't think of any situation where the quality would be equivalent. Instead, the quality will vary between slightly worse and significantly worse.
The first figure has four of my favorite images ever. They show the consequences of ice damage. Every single Alcor patient has imperfect perfusion and many have bad or no perfusion. This means that every Alcor patient probably has some of the damage shown in those images. That damage is unnecessary and is never present in aldehyde fixation.
Even assuming no ice, as their paper tries to claim, delay or elimination of aldehyde will always result in inferior structural quality. This is the strong consensus of the entire scientific community. It's not the slightest bit controversial to flatly state that aldehyde results in better quality and it's frustrating to have to keep repeating this as if it's some sort of new information.
I really can't figure out why they are still so enamored by cryo. On the Biostasis Substack,
https://biostasis.substack.com/p/biosta ... =146726813
Max says the reason is:
I really don't understand this explanation. We're not preserving brains so that we can investigate biological function or to be relevant to future medical applications. We're preserving brains in order to survive.Previously, the best whole-brain ultrastructural preservation appeared to require aldehyde fixation before cooling. While effective for structural studies, fixation prevents meaningful investigation of biological function and is less relevant to future medical applications.
This explanation is also baffling. You may not strictly need aldehyde to retain some structure, but the quality would sure be a lot better. If the quality is better, why on earth wouldn't you use it? The authors seem to have an emotional attachment to cryo because there just isn't any rational explanation.We conclude that both animal and human brains can be cryopreserved by vitrification with predominant retention of ultrastructural integrity without the need for prior aldehyde fixation. This observation has direct relevance to the feasibility of human cryopreservation, for which direct evidence has been lacking until this report. It also provides a starting point for perfecting brain cryopreservation.