There is a decent chance that we are already at the freezing part of 2. For instance, a defrosted vitrified rabbit brain apparently appeared to be in good order, though I assume we don’t know how to reattach brains to rabbits, alas.
The reference was aldehyde-stabilized cryopreservation, which is quite a bit different than a typical vitrification procedure. In particular, you can’t just rewarm the tissue and expect it to function at all. When aldehyde-stabilized cryopreservation won the Large Mammal BPF Prize in 2018, the authors of the announcement had this to say about the technique,
It is important to understand that the researchers did not actually revive a pig or pig brain. The first step in the ASC procedure is to perfuse the brain’s vascular system with the toxic fixative glutaraldehyde, thereby instantly halting metabolic processes by covalently crosslinking the brain’s proteins in place, and leading to death by contemporary standards (but not necessarily information-theoretic standards). Glutaraldehyde is sometimes used as an embalming fluid, but is more commonly used by neuroscientists to prepare brain tissue for the highest resolution electron microscopic and immunofluorescent examination. It should be obvious that such irreversible crosslinking results in a very, very dead brain making future revival of biological function impossible. So, it is reasonable to ask: “What is the point of a procedure that can preserve the nanoscale structure of a person’s brain when biological revival is impossible?” The answer lies in the possibility of future non-biological revival.
A growing number of scientists and technologists believe that future technology may be capable of scanning a preserved brain’s connectome and using it as the basis for constructing a whole brain emulation, thereby uploading that person’s mind into a computer controlling a robotic, virtual, or synthetic body. The Brain Preservation Prize challenged the scientific community to develop a ‘bridge’ to that future mind uploading technology. The similarity to cryonics is obvious, but in this case the possibility of biological revival was dismissed as currently not feasible. Focus was instead directed toward provably preserving the information content of the brain as encoded within the connectome. Quoting from a recent video presentation by BPF President Kenneth Hayworth: “Aldehyde-Stabilized Cryopreservation is cryonics for uploaders.”
The reference was aldehyde-stabilized cryopreservation, which is quite a bit different than a typical vitrification procedure. In particular, you can’t just rewarm the tissue and expect it to function at all. When aldehyde-stabilized cryopreservation won the Large Mammal BPF Prize in 2018, the authors of the announcement had this to say about the technique,