Seems like they’re using this as a fixative (not too different from the old formaldehyde solution used to preserve museum specimens).
It also kills the cells by crosslinking the proteins. Seems to me like this would be a problem if you’re thinking of somehow reviving the brain… not to mention the problem of grafting it onto a new body.
I’m confused, but I suspect I’m not going to be enlightened here… This technique uses gluteraldehyde, a chemical that’s been used to fix biological samples since approximately the dawn of time. It works by cross-linking proteins, which is massive and irreversible damage, but if done right it preserves most sub-cellular structures for analysis. Fixation using glutaraldehyde or the related formaldehyde is a standard method for analyzing sliced up brains.
This technique first fixes a brain with glutaraldehyde, then perfuses it with cryoprotectants and freezes it. After thawing and slicing up for histology, the result is… no worse than a plain glutaraldehyde-fixed brain!
Vitrification is what is usually used in cryonics now. It uses cryoprotectants that interfere with crystal formation to allow amorphous solid state tissue preservation. Vitrify means to make a glass, because glass too is made of something (silica) that can form crystals, but by adding some simple compounds that interfere with crystal formation we get an amorphous material.
Something else that does the same thing is taking sugar crystals and adding some compounds to make candy glass and hard sweets.
Right now one of the biggest issues with vitrification is that Liquid nitrogen is a great deal colder than the glass transition state of vitrified tissue and because of the size of the brain it tends to cool past the glass transition state unevenly which can cause thermal shock and cracks to form.
The basic thought is that everything is still the same spot and in order to revive somebody we would have to be able to go in with nanotech and make tweaks to chemistry and such
So rebonding on the molecular scale the sites of these cracks isn’t that big a deal.
The new techniques to maintain head at the glass transition temp to avoid going further down and risking the thermal shock that cause them in the first place.
It seems that both your OP and lazybratsche’s both reference the same study (how many Robert McIntyres are there doing brain cryopreservation?
Both cites specify that the procedure uses glutaraldehyde as a fixing agent.
And that it appears that it is the first step in the process.
Aside from any fractures induced by uneven cooling, how do you “un-link” the protein?
A rabbit is small enough (and cheap enough) that it should be possible to preserve the brain in situ and then restore it.
When that trick is accomplished, it will be time to shout about possible human preservation/restoration.
The part about “we will figure it out sometime in the future” sounds a whole lot like “and then a miracle happens and we all live forever”.
And I guess we all hope that all the frozen heads and bodies will eventually be discarded. AIUI, some are on a pay-as-you-go storage plan. When the money stops coming, the bodies go in the landfill.
If the miracle does happen and we start re-animating people, how do we break it to folks that all those placed in storage prior to 2130 are actually DEAD - really, really dead.
“Sorry for the inconvenience” would seem awkward.
I am a molecular biologist who has done a fair amount of work with fixed tissues, and I’m well aware of the benefits and drawbacks of fixation.
A fixative like formaldehyde or gluteraldehyde does massive and irreversible damage to a sample. A lot of structural and biochemical information is lost forever.
Proteins are chemically modified and cross-linked to other proteins, so are completely non-functional. Enzymatic activity is destroyed. In the dense environment inside a cell or right on its surface, that locks proteins in place. Proteins outside the cell may not be reliably fixed, and will be washed away during the fixing and freezing process. Small molecules, including important things like neurotransmitters, will also be washed away.
Some delicate sub-cellular structures are also destroyed. This includes important neuronal structures, such as new synapses that are just beginning to bud off from axons/dendrites. There are probably a ton of structures that we don’t even know are missing (in recent years there have been a lot of discoveries of structures that are only visible with new live-imaging techniques).
Of course, fixation done right will preserve a lot of interesting structural and biochemical information, but any current technique (including that linked by the OP) cannot preserve enough to allow resurrection or reproduction of a living brain.
By analogy, consider the ancient city of Pompeii. After the eruption of Pompeii, it was covered in a thick layer of volcanic ash. That preserved the city extremely for future archaeological studies, but I think we can all agree that the city was irreversibly destroyed. The charred casts of humansand animals are not going to be resurrected any time soon.
tl;dr: A gluteraldehyde fixed brain is completely and irreversibly dead.
The paper I linked to was referenced in the article linked by the OP, so yes, both refer to the exact same research.
This paper embedded the brains in resin before making slices for electron microscopy – an entirely standard technique. It doesn’t look like the freezing procedure made any difference for slice preparation.
Gah, shouldn’t have tried to add that much via edits. What I meant to add:
This statement from a futurist cryonic foundation shares my scepticism:
I’ll also add that the concept of cryopreservation isn’t completely nuts. It works very well on a small scale for storing living human cells and some microscopic animals. And like sweat209 mentions, this usually is accomplished with some combination of cryoprotectants and flash-freezing. However freezing a living human brain is orders of magnitude harder than freezing a living nematode, 302-neuron brain and all. (The nematode also has many adaptations to survive freezing, the result of the evolutionary pressure of hundreds of millions of winters…)
Awaken ye not the Ancient Ones of Largish Ears. For they are greatly fierce beyond their size. Bringeth always with ye the Holy Hand Grenade. And forgetteth ye never the count – upon pain of Dethe most violent and Foule.