You say no frozen human brain has been examined. Have any frozen brains been examined?
I’m not an expert. To my knowledge mainstream cryobiological techniques allow the preservation of very thin slices of brain tissue maintaining structural and functional integrity, but larger samples don’t seem to be preservable with current technology (read the opinion of PZ Myers, an evolutionary biologist who studies the vertebrate nervous system and applies these techniques in his research).
Alcor, a cryonics organization, appear to have performed cryopreservation experiments on a whole rabbit brain. Apparently, they found cell membrane distortions but no ice formation. I don’t know whether these results were replicated by independent researchers or even whether they were published in peer-reviewed literature. In any case, a rabbit brain is less than 1/100th of a human brain by mass, hence it is obviously much easier both to perfuse with cryoprotectants and to cool quickly.
EDIT:
What about the claims in the original link that organ transplants could be greatly facilitated if organ freezing techniques were developed. Could you comment on that claim in the context of your knowledge?
I agree that if organ cryopreservation were available, it would facilitate organ transplants. In principle perhaps you could even clone your own organs and freeze them for future use instead of keeping them alive in an animal hosts.
As far as I know, this is already possible in humans for samples of ovarian tissue large enough to restore reproductive function after chemotherapy and there is animal and human experimentation on whole ovary cryopreservation.
Preservation of larger organs is not possible with current technology, and we can’t know whether it will be ever be possible, since the square-cube law appears to be an obstacle difficult to overcome. If I were to guess I’d say that it will require much better biocompatible cryoprotectants to be administered pre-ischemia (or maybe even genetic engineering to make the cells produce cryoprotectants themselves, like some species of animals do) and probably also some drug (or genetic agumentation) to significantly delay ischemic damage.
I’m not an expert. To my knowledge mainstream cryobiological techniques allow the preservation of very thin slices of brain tissue maintaining structural and functional integrity, but larger samples don’t seem to be preservable with current technology (read the opinion of PZ Myers, an evolutionary biologist who studies the vertebrate nervous system and applies these techniques in his research).
Alcor, a cryonics organization, appear to have performed cryopreservation experiments on a whole rabbit brain. Apparently, they found cell membrane distortions but no ice formation. I don’t know whether these results were replicated by independent researchers or even whether they were published in peer-reviewed literature. In any case, a rabbit brain is less than 1/100th of a human brain by mass, hence it is obviously much easier both to perfuse with cryoprotectants and to cool quickly.
EDIT:
I agree that if organ cryopreservation were available, it would facilitate organ transplants. In principle perhaps you could even clone your own organs and freeze them for future use instead of keeping them alive in an animal hosts. As far as I know, this is already possible in humans for samples of ovarian tissue large enough to restore reproductive function after chemotherapy and there is animal and human experimentation on whole ovary cryopreservation.
Preservation of larger organs is not possible with current technology, and we can’t know whether it will be ever be possible, since the square-cube law appears to be an obstacle difficult to overcome. If I were to guess I’d say that it will require much better biocompatible cryoprotectants to be administered pre-ischemia (or maybe even genetic engineering to make the cells produce cryoprotectants themselves, like some species of animals do) and probably also some drug (or genetic agumentation) to significantly delay ischemic damage.