Cryopreservation doesn't have to cause damage. For instance, Aldehyde Stabilized Cryopreservation (on pigs) doesn't https://doi.org/10.1016/j.cryobiol.2015.09.003

1. I don't think this is done at any of the main cryonics organizations, right? Their methods are damaging in perhaps less predictable ways than this mechanism.

2. I think the statement

Cryopreservation doesn't have to cause damage

is deceptive and I wouldn't want it being shared without further context. I had a conversation with my expert-friend about this method and the type of damage it causes.

Quoting some parts of my text message conversation with this expert friend who wishes to be anonymous:

(Him) I had never seen this article before, but it's pretty cool. The technique it describes supposedly preserves the brains ultrastructure (i.e. connections between neurons etc) for connectome mapping and neural research. However, the technique utterly fails at (and isn't trying) to preserve viability. In this case, the cryopreservation isn't causing "damage" to the structure of the brain, preserving it for connectome research....BUT they did that by obliterating any hope for brain viability post thawing by exposing it to extremely high concentrations of toxic chemicals.

(Me) Interesting. I'm not familiar with the connectome really, but to you does that mean that this is a method that sounds promising for e.g. future digital brain construction but sounds really bad for e.g. biological reanimation?

(Him) Yeah, that's a good summary. The question with digital brain reconstruction will be whether the connectome actually has all of the information you need or if there are other issues (analogous to how DNA is mediated by epigenetics).

(Me) Yeah, I could be wrong but I'd thought most people were thinking that chemical movements in the brain contained significant information that would probably need to be recreated accurately to reanimate someone who was accurate to the person who had passed.

(Him) That's my impression too.

(Me) How do the toxic chemicals obliterate hope of brain viability post-thawing?

(Him) I don't know the exact mechanism....but they're using extremely high concentrations of very toxic chemicals. I think the tissue is fucked from the toxic chemicals, but it depends on the exact type of toxicity (which I'm not sure about and the paper doesn't go into). In a certain sense, anything toxic "physically" damages the tissue at a certain scale...it might cause osmotic swelling or shrinkage, damage DNA, damage cell membranes, block oxygen (which causes all sorts of other damage), etc. Importantly for this application, it's not damaging the overall structure of the brain, so the connectome is still intact and can be studied. You could think of it like degrading the steel in a building. The overall structure will be intact, but it's now structurally unsound and will collapse if exposed to anything. Something is wrong about the structure on small scales, but the large scale structure appears normal.

Regarding your second response:

Brain biopsies are performed in hospitals e.g. during brain cancer diagnostics. They should not be dangerous to perform

The first paper I looked at on brain biopsies (https://link.springer.com/article/10.1007/s10143-019-01234-w) says:

The mortality rate varies from 0.7 to 4%. Overall morbidity ranges from 3 to 13%. Most of the complications are revealed by the following symptoms: neurological impairment (transient or permanent), seizure, and unconsciousness. Symptomatic hemorrhage range varies from 0.9 to 8.6%, whereas considering asymptomatic bleeding, the range may be up to 59.8%.

That sounds like a high risk of being very damaging to me, and that's from one biopsy by expert medical staff vs. your proposed multiple by non-experts.