The Brain Preservation Foundation’s Small Mammalian Brain Prize has been won with fantastic preservation of a whole rabbit brain using a new fixative+slow-vitrification process.
- BPF announcement (21CM’s announcement)
The process was published as “Aldehyde-stabilized cryopreservation”, McIntyre & Fahy 2015 (mirror)
We describe here a new cryobiological and neurobiological technique, aldehyde-stabilized cryopreservation (ASC), which demonstrates the relevance and utility of advanced cryopreservation science for the neurobiological research community. ASC is a new brain-banking technique designed to facilitate neuroanatomic research such as connectomics research, and has the unique ability to combine stable long term ice-free sample storage with excellent anatomical resolution. To demonstrate the feasibility of ASC, we perfuse-fixed rabbit and pig brains with a glutaraldehyde-based fixative, then slowly perfused increasing concentrations of ethylene glycol over several hours in a manner similar to techniques used for whole organ cryopreservation. Once 65% w/v ethylene glycol was reached, we vitrified brains at −135 °C for indefinite long-term storage. Vitrified brains were rewarmed and the cryoprotectant removed either by perfusion or gradual diffusion from brain slices. We evaluated ASC-processed brains by electron microscopy of multiple regions across the whole brain and by Focused Ion Beam Milling and Scanning Electron Microscopy (FIB-SEM) imaging of selected brain volumes. Preservation was uniformly excellent: processes were easily traceable and synapses were crisp in both species. Aldehyde-stabilized cryopreservation has many advantages over other brain-banking techniques: chemicals are delivered via perfusion, which enables easy scaling to brains of any size; vitrification ensures that the ultrastructure of the brain will not degrade even over very long storage times; and the cryoprotectant can be removed, yielding a perfusable aldehyde-preserved brain which is suitable for a wide variety of brain assays…We have shown that both rabbit brains (10 g) and pig brains (80 g) can be preserved equally well. We do not anticipate that there will be significant barriers to preserving even larger brains such as bovine, canine, or primate brains using ASC.
- previous discussion: Mikula’s plastination came close but ultimately didn’t seem to preserve the whole brain when applied.
- commentary: Alcor, Robin Hanson, John Smart, Evidence-Based Cryonics, Vice, Pop Sci
To summarize it, you might say that this is a hybrid of current plastination and vitrification methods, where instead of allowing slow plastination (with unknown decay & loss) or forcing fast cooling (with unknown damage and loss), a staged approach is taking: a fixative is injected into the brain first to immediately lock down all proteins and stop all decay/change, and then it is leisurely cooled down to be vitrified.
This is exciting progress because the new method may wind up preserving better than either of the parent methods, but also because it gives much greater visibility into the end-results: the aldehyde-vitrified brains can be easily scanned with electron microscopes and the results seen in high detail, showing fantastic preservation of structure, unlike regular vitrification where the scans leave opaque how good the preservation was. This opacity is one reason that as Mike Darwin has pointed out at length on his blog and jkaufman has also noted that we cannot be confident in how well ALCOR or CI’s vitrification works - because if it didn’t, we have little way of knowing.
EDIT: BPF’s founder Ken Hayworth (Reddit account) has posted a piece, arguing that ALCOR & CI cannot be trusted to do procedures well and that future work should be done via rigorous clinical trials and only then rolled out. “Opinion: The prize win is a vindication of the idea of cryonics, not of unaccountable cryonics service organizations”
…“Should cryonics service organizations immediately start offering this new ASC procedure to their ‘patients’?” My personal answer (speaking for myself, not on behalf of the BPF) has been a steadfast NO. It should be remembered that these same cryonics service organizations have been offering a different procedure for years. A procedure that was not able to demonstrate, to even my minimal expectations, preservation of the brain’s neural circuitry. This result, I must say, surprised and disappointed me personally, leading me to give up my membership in one such organization and to become extremely skeptical of all since. Again, I stress, current cryonics procedures were NOT able to meet our challenge EVEN UNDER IDEAL LABORATORY CONDITIONS despite being offered to paying customers for years. Should we really expect that these same organizations can now be trusted to further develop and properly implement such a new, independently-invented technique for use under non-ideal conditions?
Let’s step back for a moment. A single, independently-researched, scientific publication has come out that demonstrates a method of structural brain preservation (ASC) compatible with long-term cryogenic storage in animal models (rabbit and pig) under ideal laboratory conditions (i.e. a healthy living animal immediately being perfused with fixative). Should this one paper instantly open the floodgates to human application? Under untested real-world conditions where the ‘patient’ is either terminally ill or already declared legally dead? Should it be performed by unlicensed persons, in unaccountable organizations, operating outside of the traditional medical establishment with its checks and balances designed to ensure high standards of quality and ethics? To me, the clear answer is NO. If this was a new drug for cancer therapy, or a new type of heart surgery, many additional steps would be expected before even clinical trials could start. Why should our expectations be any lower for this?
The fact that the ASC procedure has won the brain preservation prize should rightly be seen as a vindication of the central idea of cryonics –the brain’s delicate circuitry underlying memory and personality CAN in fact be preserved indefinitely, potentially serving as a lifesaving bridge to future revival technologies. But, this milestone should certainly not be interpreted as a vindication of the very different cryonics procedures that are practiced on human patients today. And it should not be seen as a mandate for more of the same but with an aldehyde stabilization step casually tacked on. …