Sparks Brain Preservation
A Non-profit Organization
Traditional cryonics is the cryopreservation of a brain in liquid nitrogen. It is used by companies like Alcor, the Cryonics Institute, and Tomorrow Biostasis.
The technique used at Sparks Brain Preservation is more advanced, involving aldehyde preservation, also known as chemical preservation or chemical fixation, prior to any cooling. After fixation, the brain is then stored at a lower temperature in a refrigerator, freezer, or liquid nitrogen, depending on the situation.
Here is some information about the two different techniques:
Aldehyde is extensively used by scientists and is considered to be the gold standard in mainstream science for brain preservation. Nearly all microscopic images of large volumes of brain tissue ever taken have used aldehyde. Cryopreservation is also used by scientists, but the quality is known to be inferior when the goal is to retain the structural connectome, so it's simply not used by anyone for that purpose.
Some scientists who are involved in traditional cryonics defend its use because they see it as a path to Suspended Animation. They envision being able to cryopreserve organs and then revive them, and then eventually move to full suspended animation. Unfortunately, there is broad consensus among mainstream scientists that we are at least 100 years away from such technology.
Evidence-based medicine (EBM) means making clinical decisions based on the best current evidence and clinical expertise. The evidence must support currently available outcomes. At SBP, our desired outcome is structural brain preservation, so all evidence must support that outcome. Revival cannot be considered because it's not a currently available outcome. Evidence that might support the outcome of revival is completely ignored. This rigorous approach leads to better preservation quality.
In traditional cryonics, the desired outcome seems to instead be revival, even though that's not a currently available outcome. This makes it experimental rather than evidence-based. Experimental research should only be provided in a research setting and should never be applied to patients when evidence-based care is instead available.
To qualify as legitimate research involving human subjects, there must be certain scientific elements present. These generally include things like feedback, iterative learning, knowledge gain, peer review publication, randomization, a control group, ethical oversight, falsifiability, and reproducibility. While these elements may be present in various side projects, they are not present in the patient care activities. There is no currently available outcome which is being measured. Cryopreservation of humans is not research in any meaningful sense, and it's wrong to claim that it is research.
Aldehyde works by creating covalent cross-links between proteins. This deliberate arrest of metabolism and molecular diffusion is exactly what makes aldehyde fixation so valuable for preserving brain structure. A few traditional cryonics advocates claim that this cross-linking is a form of damage that is incompatible with biological revival. But the technology for biological revival is at least 100 years in the future. Damage in current ideal cryonics cases is extensive, including at the molecular level. Technology that is capable of altering covalent bonds is already clearly going to be a requirement. It's inconsistent to reject aldehyde fixation for introducing covalent bonds when molecular damage of an equivalent nature is already present in all existing traditional cryonics cases.
Perfusion is known to be unreliable and incomplete in nearly all current human cases, whether for traditional cryonics or fixation. This means that there are always areas where the chemicals being perfused will not reach. This is catastrophic for traditional cryonics because those areas will then freeze and cause brain damage. Because of logistical issues, a fairly large percentage of traditional cryonics patients actually have their entire brain Straight Frozen, which may very well cause complete information-theoretic death. This should not be tolerated. Freezing damage is unacceptable and is entirely avoidable in all cases by first using aldehyde. If subsequent subzero cooling is desired, this is only considered after waiting many months for the cryoprotectant to diffuse to all tissue before considering subzero cooling.
Traditional cryonics companies promote revival as the goal rather than structural preservation. This sounds more exciting and more desirable than our goal of structural preservation. That marketing choice is causing patients to choose the wrong technology for their brain preservation. Because it's not evidence-based and because the wrong outcome is being pursued, freezing damage is accepted in traditional cryonics as unavoidable. This is directly harming patients.
Aldehyde preservation cost can approach zero in many cases. This allows us to save many more lives and it also reduces the risk and complexity. When large amounts of money are not involved, everyone is safer. It means much lower overall risk of organizational failure.
Alcor has posted electron micrographs of brain tissue that has been preserved with their protocol in an ideal situation:
https://www.cryonicsarchive.org/library/alcor-new-york-academy-of-sciences-paper/
https://www.cryonicsarchive.org/library/new-cryopreservation-technology/
The images demonstrate significant dehydration and they don't even look like normal brain tissue. They claim that this mechanical damage is reversible, but this is debatable and lacks evidence. By using aldehyde prior to any cryopreservation, this damage is avoided.
In 2016, Robert McIntyre and Greg Fahy published a paper describing Aldehyde Stabilized Cryopreservation (ASC) which combined both techniques into a single protocol and demonstrated excellent quality of preservation of brain tissue. However, the additional step of cryopreservation did not actually improve the quality of preservation. Since it also didn't reduce the quality, we do offer cryopreservation after our standard fixation to those who ask for it.
The Q10 rule of thumb applies between 0 C and 40 C. The rule states that biochemical reaction rates are cut in half for every reduction of 10 degrees. For this reason, ice baths are frequently used in cryonics to slow reaction rates to buy more time to perform the perfusion. In contrast, if aldehyde can be quickly introduced, then most reactions stop and the Q10 rule no longer applies. Aldehyde is an alternative to cooling in this temperature range.
When cryopreservation is used alone, it can take hours to first cool the body sufficiently for cryoprotectant perfusion and then hours to perfuse the cryoprotectant chemicals through the circulatory system. During that entire time, there's nothing locking the molecules in place, which results in significant damage. Locking the molecules in place many hours earlier with aldehyde preserves more information.
Conversion from liquid to solid happens at -123 C in cryopreservation. After many hours, this phase change is what finally locks the molecules in place. When aldehyde is used, the molecules are locked in place much sooner and the temperature doesn't matter.
We perform cooling after using aldehyde in order to keep the lipids solid. Aldehyde does a great job of quickly locking the proteins in place, but the lipids are only immobilized because they are trapped in a web of proteins. If we allow the lipids to remain liquid at room temperature, it's somewhat plausible that a small portion of the lipids might shift position. Cooling after aldehyde preservation is recognized in mainstream science to probably result in better long-term quality.
Pascal's Wager is an argument that has been adapted to cryonics. The argument is that if there’s even a small chance that cryonics could work, then choosing it would offer extraordinary benefit. If it fails, you would lose little because you'd be dead anyway. Therefore, the rational choice would to sign up for cryonics. With the original Pascal's Wager, the obvious fallacy is that you might choose the wrong god. The cryonics adaptation suffers from the same fallacy. You might choose traditional cryonics, but aldehyde fixative might turn out to be the only way to get a good preservation.
For storage over centuries, there are claims that cryopreservation might provide better stability, but there is no good evidence for that yet. There is also the known problem of cracking. While cracking is unlikely to cause any significant damage, some attempts have been made in cryonics to avoid cracks by storing at an intermediate temperature of -120 C. Those attempts have not been very successful because it's a difficult problem and because it raises the cost.
This is an argument for why traditional cryonics might be better than aldehyde. But the argument quickly falls apart. Whether you use chemical fixative or cryoprotectant, you must get the chemicals to all areas of the brain or there will be poor preservation. In the case of cryopreservation, the poorly perfused areas are subjected to a straight freeze. That’s probably not compatible with preservation of memories as explained here: Straight Freeze
All cryonics companies need to switch to aldehyde preservation prior to cooling. It's time to end the freezing damage and move to evidence-based care.