A familiar trope in science fiction is the cryopreserved time traveller, their body deep-frozen in suspended animation, then thawed and reawakened in another decade or century with all of their mental and physical capabilities intact.

Researchers attempting the cryogenic freezing and thawing of brain tissue from humans and other animals — mostly young vertebrates — have already shown that neuronal tissue can survive freezing on a cellular level and, after thawing, a functional one to some extent. But it has not been possible to fully restore the processes necessary for proper brain functioning — neuronal firing, cell metabolism and brain plasticity.

A team in Germany has now demonstrated a method for cryopreserving and thawing mouse brains that leaves some of this functionality intact. The study, published on 3 March in Proceedings of the National Academy of Sciences 3, details the authors’ use of a method called vitrification, which preserves tissue in a glass-like state, along with a thawing process that preserves living tissue.

“If brain function is an emergent property of its physical structure, how can we recover it from complete shutdown?” asks Alexander German, a neurologist at the University of Erlangen–Nuremberg in Germany and lead author of the study. The findings, he says, hint at the potential to one day protect the brain during disease or in the wake of severe injury, set up organ banks and even achieve whole-body cryopreservation of mammals.

Mrityunjay Kothari, who studies mechanical engineering at the University of New Hampshire in Durham, agrees that the study advances the state of the art in cryopreservation of brain tissue. “This kind of progress is what gradually turns science fiction into scientific possibility,” he says. However, he adds that applications such as the long-term banking of large organs or mammals remain far beyond the capabilities of the study.

Article Featured in Nature.

‘Cryosleep’ remains the preserve of science fiction, but researchers are getting closer to restoring brain function after deep freezing.