5 ms·
Yeah, I freeze and thaw cells constantly without much trouble--just plop those suckers in a solution of 10% DMSO and a serum-containing isotonic liquid then thr
by cryoshon 11y ago
Yeah, I freeze and thaw cells constantly without much trouble--just plop those suckers in a solution of 10% DMSO and a serum-containing isotonic liquid then throw into the freeze-assist device, then put that into the -80C freezer and transfer it to the liquid nitrogen freezer the next morning. Everyone does it this way, and has for years. I've always wondered if the freezing and thawing process subtly changes cell functioning (beyond the time given to cells to rest after being thawed), but I'm guessing if it were the case someone would have noticed it by now.
The bugger that haunts human cryonics is that thawing is never perfect because the cryoprotectants used to prevent ice-crystals within the cells are usually toxic. If you freeze cells that are measured to be 100% viable/alive at the time (very common) then thaw them using best practices, you're going to have some cell death-- maybe 1-5% if you're fast (less time spent in toxic cryoprotectant) and lucky. If you're unlucky or slow, you can look at 25-45% of your originally healthy cells being dead upon completion of the thawing process. The remaining cells are usually extremely discombobulated, and can take days to return to their baseline. This is completely fine if you're tooling around in a research lab or industrial lab, but even a 1% loss is probably too much for a human brain to bear and remain the same as before.
I suppose that if you work under the assumption that the future technology cryonics relies on for thawing will exist, cell loss during thaw will not be a problem; I find this possibility to be fairly likely over a long time span. Alternatively, you could assume that there will be advanced ways of restoring brain function or generating fresh neurons after systemic damage-- quite a stretch if you ask me, but it's conceivable. I think that ultimately the goals of cryonics will be scientifically realizable for those who were most recently preserved.
- 336f5 11y ago> This is completely fine if you're tooling around in a research lab or industrial lab, but even a 1% loss is probably too much for a human brain to bear and remain the same as before. You probably lose at least that many neurons over a lifetime; consider the shrinking volume of the brain with age. And losses definitely easily exceed 1% in early Alzheimer's or dementia, but while not fun, people with early Alzheimer's clearly have not died or ceased to exist! (And anyway, the real question about the dead cells is whether they still have the information about their synaptic weights and other functional information. Being able to revive the cell is overkill; the focus on revival is as an _a fortiori_ argument, since any revival proves that, even in the absence of future scanning advances, it must be possible.)
- ethbro 11y ago(Not a biology guy) It would seem like there should be a difference between an operational brain losing neurons and a suspended brain losing neurons? I'd assume that if inter-neuron communication speed is anywhere on the same order as the time-between-individual-neuron-loss, then that would alleviate the effect somewhat, no? My understanding was there was a lot of redundancy up there, so it would make sense that the brain would resilver itself in certain scenarios.
- JoshTriplett 11y ago> I'd assume that if inter-neuron communication speed is anywhere on the same order as the time-between-individual-neuron-loss, then that would alleviate the effect somewhat, no? My understanding was there was a lot of redundancy up there, so it would make sense that the brain would resilver itself in certain scenarios. The brain is remarkably resilient and adaptive; people manage to recover at least partial function even after major strokes. And, quite frankly, I'd take "functioning like a stroke victim" over "dead" any day.
- JoshTriplett 11y ago> Yeah, I freeze and thaw cells constantly without much trouble--just plop those suckers in a solution of 10% DMSO and a serum-containing isotonic liquid then throw into the freeze-assist device, then put that into the -80C freezer and transfer it to the liquid nitrogen freezer the next morning. Everyone does it this way, and has for years. I've always wondered if the freezing and thawing process subtly changes cell functioning (beyond the time given to cells to rest after being thawed), but I'm guessing if it were the case someone would have noticed it by now. Has anyone tested this on a macroscopic creature? In particular, one complex enough to demonstrate memory, which could be tested afterward? I've seen one or two reports of such tests, but nothing going into detail about the degree of function afterward.
- adrianN 11y agoThere are a number of amphibians that freeze during winter as part of their natural life cycle. They seem to be fine.
- larubbio 11y agohttps://www.youtube.com/watch?v=UuhEHNey37Q https://www.youtube.com/watch?v=UuhEHNey37Q The above video is a short demonstration of one such amphibian
- lnanek2 11y agoDid you read the article we're commenting on? It stated roundworms have been frozen and illustrated learned behaviors to certain scents afterwards. It also stated rabbit brain tissue retained long term memories.
- JoshTriplett 11y agoThe article mentioned tests on brain tissue, subsequent analysis of which suggests it wouldn't have affected memory, but not actual tests of a living organism in practice.
- cryoshon 11y ago