Cryonics provider Alcor have today published their position on aldehyde-stabilized cryopreservation. This is the vitrification methodology used by 21st Century Medicine to win the first stage of the Brain Preservation Prize earlier this month. The researchers demonstrated exceptional preservation of fine structure in mammalian brains, which by the present consensus in neurobiology is a compelling argument that the data of the mind encoded in that structure is also preserved. This in turn lends weight of validation to the existing methods of vitrification used by the cryonics industry, and can be placed alongside last year's results showing preservation of memory in vitrified and restored nematode worms.
It is worth noting that end goals are not aligned among advocates for cryopreservation and other forms of tissue preservation that can in principle maintain the data of the mind. This is important because end goals steer today's decisions on research, development, and advocacy, such as the type of approach used to preserve brain tissue. There is a strong contingent, the Brain Preservation Foundation founders among their number, that sees cryopreservation as a step on the road towards mind uploading. Their expectation is that preserved minds will be scanned and run in emulation, the original cryopreserved brain discarded or destroyed in the process. From this viewpoint, tissue restoration isn't even a question, and it certainly isn't a goal to optimize for. All optimization of technique should go towards provable preservation.
Those of us who think that a copy is not the self, and that the original tissue must be restored in order for a preserved individual to actually survive, have different and arguably harder goals. Not only do we want provable preservation of neural structure but we also want to make life easier for those who will one day work to restore the archives of cryopreserved brains. In this I find myself on the fence; I'm not certain that the additional chemical entanglements of, for example, aldehyde fixation raise the bar that much in comparison to what we already know future restoration requires. Molecular nanotechnology, a full understanding of brain biochemistry, and absolute control over cellular biochemistry are the plausible requirements at the high level, and communities or entities capable of deploying that mix of capabilities shouldn't be much daunted by whatever we have done today, provided that we succeeded in preserving the structure and did not destroy the biological macromolecules involved.
We are pleased that vitrification, the same basic approach that Alcor Life Extension Foundation has utilized since 2001, is finally being recognized by the scientific mainstream as able to eliminate ice damage in the brain. Alcor first published results showing this in 2004. The technology and solutions that Alcor uses for vitrification, a technology from mainstream organ banking research, were actually developed by the same company (21st Century Medicine) that developed Aldehyde-Stabilized Cryopreservation (ASC) and has now won the Brain Preservation Prize.
ASC under the name "fixation and vitrification" was first proposed for cryonics use in 1986. ASC enables excellent visualization of cellular structure - which was the objective that had to be met to win the prize - and shows that brains can be preserved well enough at low temperature for neural connectivity to be shown to be preserved. Vitrification without fixation leads to dehydration. Dehydration has effects on tissue contrast that make it difficult to see whether the connectome is preserved or not with electron microscopy. That does not mean that dehydration is especially damaging, nor that fixation with toxic aldehyde does less damage. In fact, the M22 vitrification solution used in current brain vitrification technology is believed to be relatively gentle to molecules because it preserves cell viability in other contexts, while still giving structural preservation that is impressive when it is possible to see it.
While ASC produces clearer images than current methods of vitrification without fixation, it does so at the expense of being toxic to the biological machinery of life by wreaking havoc on a molecular scale. Chemical fixation results in chemical changes (the same as embalming) that are extreme and difficult to evaluate in the absence of at least residual viability. Certainly, fixation is likely to be much harder to reverse so as to restore biological viability as compared to vitrification without fixation. Fixation is also known to increase freezing damage if cryoprotectant penetration is inadequate, further adding to the risk of using fixation under non-ideal conditions that are common in cryonics. Another reason for lack of interest in pursuing this approach is that it is a research dead end on the road to developing reversible tissue preservation in the nearer future.
Alcor looks forward to continued research in ASC and continued improvement in conventional vitrification technology to reduce cryoprotectant toxicity and tissue dehydration. We are especially interested in utilizing blood-brain barrier opening technology such as was used to win the prize, but which pre-dated work on ASC. For cryonics under ideal conditions, the damage that still requires future repair is now more subtle than freezing damage. That damage is believed to be chiefly cryoprotectant toxicity and associated tissue dehydration. Nonetheless this is a groundbreaking result that further strengthens the already strong case that medical biostasis now clearly warrants mainstream scientific discussion, evaluation, and focus.
The folk at Evidence Based Cryonics have also put out a statement, focused on the technical details as much as the significance:
Recently we have seen scientific evidence that long-term memory is not modified by the process of whole organism cryopreservation through vitrification and revival in simple animal models (C. elegans nematode), supplementing knowledge that other small animals with nervous systems can also be healthily revived after storage in storage in liquid nitrogen at a temperature of -196C (O. jantseanus leech). Earlier we also knew that in mammalian hippocampal brain slices viability, ultrastructure, and the electrical responsiveness of the neurobiological molecular machinery that elicits long-term potentiation, a mechanism of memory, can be preserved without appreciable damage following cryopreservation. Published transmission and scanning electron microscopic images from a whole brain cryopreserved through vitrification and also indicate structural integrity.
And now, a new cryobiological and neurobiological technique, aldehyde-stabilized cryopreservation (ASC) provides a strong proof that brains can be preserved well enough at low temperature for neural connectivity (the connectome) to be completely visualized. The connectome is believed to be an important encoding mechanism for memory and personal identity (sense of self/where the mind lives) within the brain. This is a truly groundbreaking result and puts the proposition of human medical biostasis as a way to save humans who otherwise would die squarely within the realm of what may be possible.