Isochoric supercooling looks much more promising. The body does not freeze solid. The temperature is lowered to below freezing, but all fluids remain fluids.
I'm not aware of experiments with animals, and obviously not humans. But here's an experiment with human cardiac tissue [1], which went quite well.
This test was a pragmatic one directed by the needs of heart transplants. There is no brain tissue transplant as of now. But there's no reason for science to not try other tissues and then even lab animals, then even pets, and at some point humans.
I'm not aware of experiments with animals, and obviously not humans. But here's an experiment with human cardiac tissue [1], which went quite well.
[1] https://www.nature.com/articles/s42003-021-02650-9