Vitrification avoids ice. Nanobots could e.g. remove toxic compounds from extracellular areas and replace them with nontoxic solutions, and deliver yet-to-be-invented drugs that would activate upon thawing.
> Even biocompatible antifreeze proteins found in arctic oceans have a thermal threshold of 269K, which is no where near cryogenic temperature.
The stuff invented by 21st Century Medicine and used to successfully cryopreserve a rabbit kidney is a combination of the ordinary kind of penetrating antifreeze that depresses the freezing point (glycerol, EG, DMSO, and the like) with polymers that inhibit ice nucleation (functionally similar to antifreeze proteins). It has been known for a while that you can vitrify slowly by using high concentrations of the former kind of solute (depress the freezing temperature to below the glass transition temperature and the cooling rate no longer matters) but the latter lets you get away with somewhat more water in the mix, is my understanding.
There's a tradeoff when you cool things, where if you get cold enough it slows toxicity. They don't perfuse with the stuff until the brain is already cooled to near 0 degrees C, and it is ramped in concentration over time to prevent osmotic shock.
Vitrification avoids ice. Nanobots could e.g. remove toxic compounds from extracellular areas and replace them with nontoxic solutions, and deliver yet-to-be-invented drugs that would activate upon thawing.
> Even biocompatible antifreeze proteins found in arctic oceans have a thermal threshold of 269K, which is no where near cryogenic temperature.
The stuff invented by 21st Century Medicine and used to successfully cryopreserve a rabbit kidney is a combination of the ordinary kind of penetrating antifreeze that depresses the freezing point (glycerol, EG, DMSO, and the like) with polymers that inhibit ice nucleation (functionally similar to antifreeze proteins). It has been known for a while that you can vitrify slowly by using high concentrations of the former kind of solute (depress the freezing temperature to below the glass transition temperature and the cooling rate no longer matters) but the latter lets you get away with somewhat more water in the mix, is my understanding.
There's a tradeoff when you cool things, where if you get cold enough it slows toxicity. They don't perfuse with the stuff until the brain is already cooled to near 0 degrees C, and it is ramped in concentration over time to prevent osmotic shock.