Scientists Successfully Revived Brain Tissue from Suspended Animation

Yahoo

24-02-2025

This is the first time that brain tissue has been cryogenically frozen and revived without damage.
In a process called vitrification, researchers treated slices of mouse brains with cryoprotectants which protected ice crystals from forming and destroying the tissue
When the slices of brain were revived, they showed a return to electrical activity, and it is possible they may have even held on to memories
Putting humans into a state of suspended animation have been a sci-fi aspiration for decades. In Ridley Scott's iconic film Alien, the crew of the Nostromo emerge from cryo-pods as they approach a distant exoplanet, and Isaac Asimov's Foundation series sees some characters in a state of cryo-sleep for decades, sometimes more than a century. But none of that is remotely realistic—right?
Not so fast. Researcher Alexander German of the University of Erlangen-Nuremberg in Germany has now found a way to cryogenically induce a state of suspended animation in hippocampus slices from mouse brains—and then revive them. German and his team put the brain segments in a deep freeze for a week and then warmed them back up to find that electrical activity had returned to almost normal levels.
This step forward builds on previous experiments that have tried to revive cryogenically frozen mammalian tissue. A 2006 study that attempted to freeze and revive hippocampal slices from rat brains came close, but there was not enough evidence for the level of reanimation that German has now achieved. Until now, whether living brain tissue could be shut down by freezing and then regain function was unknown.
Cryopreservation involves more than just freezing. Tissue frozen without cryoprotectants is susceptible to damage from the formation of ice crystals, ultimately resulting in loss of function and cell death. This is why German's team used a method known as vitrification. Since the early 1980s, vitrification experiments have been found to preserve tissues with cryoprotectants that prevent the crystallization of ice and turn supercooled bodily fluids into a glassy, amorphous solid.
'Based on stereomicroscopy assessment of tissue swelling and crystallization, as well as the degree of electrophysical recovery, we optimized a vitrification procedure that minimizes damage,' the researchers said in a study recently posted on the preprint server bioArxiv.
The cryoprotective agents German planned on using were designed to be nontoxic and minimize the risk of tissue injury from shrinking, swelling, crystallization and cracking. Once prepared with these cryoprotectants, the brain slices were cooled to -196 °C (about -321 °F) in liquid nitrogen. This is important because a direct transfer to liquid nitrogen without cryoprotective treatment would have caused the tissue to crack. They were then kept in a -150 °C (-238 °F) freezer for a week.
When the slices of mouse hippocampus were taken out and brought up to -10 °C (14 °F), observations showed that there had been no crystallization during the cooling or rewarming phase. Tests showed that the revived brain tissue had just about fully recovered and had resume electrical activity. The fragile synapses that connect nerve cells and pass impulses through them were intact, and German thought it was even possible (although not yet proven) that memories could have been preserved.
'Normal spontaneous synaptic events revealed that brain activity re-initializes after cessation of all continuous dynamical process in the vitreous state,' he and his team said in the same study. 'Our work improves substantially upon previous attempts at cryopreserving adult brain tissue.'
Tissue from other organs, such as rat hearts and livers, have also been successfully cryopreserved and revived before. Whether this could eventually translate to putting an entire organ, even an entire organism, in a state of suspended animation requires future research. Some animals produce their own cryoprotectants as they transition to a state of torpor to avoid harsh winters. This is something else scientists could learn from in the pursuit of artificial suspended animation.
Alien and Foundation are onto something. Putting humans into a state of suspended animation during spaceflight would drastically reduce the risk of tissue damage caused by microgravity and extreme radiation. No one is trekking to Mars—at least not yet—so we still have time, but even just the thought is no less tantalizing.
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