The Brain

A Whole Rabbit Brain Has Been Cryogenically Preserved

February 10, 2016 | by Justine Alford

Photo credit: Preserved rabbit brain being removed from storage. Kenneth Hayworth/Brain Preservation Foundation

You may live on in the hearts and minds of others, but what if there was another, more radical way to keep going after you die? Say, uploading your brain to a computer so that an artificial version of you can take your place? Sounds like the plot of a Spielberg film, but believe it or not, scientists think it’s possible, and a significant stride in this direction has just been made.

Researchers have managed to cryogenically preserve the entire brain of a rabbit and then thaw it more than two days later, while keeping the cells and their vital connections intact. Although this doesn’t mean that the organ would be functional if scientists ever attempted to revive the animal, it does represent a breakthrough in the field of cryonics and lays the foundations for future work where researchers will scale-up the procedure into larger, more medically relevant animals.

The achievement, made by researchers at 21st Century Medicine, has won the group the Brain Preservation Foundation’s Small Mammal Brain Preservation Prize, narrowly pipping Max Planck researcher Shawn Mikula’s similar project on mice to the post. Described in the journal Cryobiology, this is the “first demonstration that near perfect, long-term structural preservation of an intact mammalian brain is achievable,” a BPF statement wrote.

The key to cryopreservation lies in the prevention of ice crystal formation, which can damage the cells' delicate structures. To do this, the tissue is flooded with certain “antifreeze,” or cryoprotectant chemicals that basically turn the organ into a glass, a process known as vitrification. In this case, the scientists started off by using a fixative called glutaraldehyde, which they rapidly perfused through the brain’s vasculature. As the name suggests, this fixes things in place so that they don’t begin to degrade after the flow of blood, and therefore nutrients and oxygen, is stopped.

This successfully stabilized the brain tissue so that cryoprotectants could then be diffused throughout the organ, reaching deep tissues that were inaccessible during previous attempts, leading to significant shrinkage. After the brain was vitrified, it was stored at -135ºC (-211ºF) for an extended period of time before being thawed and then cut into thin slices for examination.

Microscopy then revealed spectacularly uniform preservation throughout the brain, not just in terms of the cells and their structures but also the connections between neurons, or synapses, across which information flows. Since it is believed that our memories are written in these connections, collectively known as the “collectome,” the possibility has been thrown out there that one day, it might be possible to read this information and upload it onto an artificial system, a kind of “synthetic” revival. This, scientists say, would be easier than attempting to keep the tissue functional and viable in preparation for revival of the body from a cryogenic state, for example after a cure for a deadly or severely debilitating disease has been found.  

Whether or not this goal is realistic remains to be seen, but what the scientists have achieved is in no doubt impressive. The next stage for the BPF’s competition is achieving the same with a pig brain, and one has already been submitted for review. Watch this space. 

Image in text: The rabbit brain going in for storage. Kenneth Hayworth/Brain Preservation Foundation

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