Some cold-blooded animals have natural antifreeze to prevent ice from forming at sub zero temperature. But it only works so far. Once water freezes, there is nothing to prevent crystallization which causes it to expand, destroying every cell in the body. It’s just the physics of how the water molecule works, and as Scotty would say you canna change the laws of physics. Walt Disney would love it if we could (he had his head cryonically frozen).
Anyway, what is the goal here? The goal is to slow down the metabolism of a the human being for a very long period of time without damage or side effects. What is the minimal external supplied energy (heat, food, etc) to keep the bodily functions operating properly. Also, what about atrophy and bone density (especially in a low gravity environment).
Anyway, it seems like you might be able to apply an external EM source that might suspend the the water molecules thus preventing freezing crystalization.