The decision of a teenage girl to have her body cryogenically frozen in the hope of being reanimated by medical advances in the future is one with which many could sympathise. But does current evidence suggest the gamble will pay off, or does cryonics simply give desperate people false hope dressed up in the language of science?



Can humans be frozen and defrosted successfully?

There are two advances that make cryonics a little less far-fetched that it once was. The first is vitrification. As Arctic explorers and mountaineers have learned, humans are not designed to be frozen and defrosted. When our cells freeze, they fill with ice crystals, which break down cell walls as they expand, reducing our body to mush once it is warmed up again.

How does vitrification work?

Vitrification prevents this by replacing the blood with a mixture of antifreeze-like chemicals and an organ preservation solution. When cooled to below -90C, the fluid becomes a glass-like solid.

The technique has substantially improved the reliability of freezing and thawing embryos, and particularly eggs, in fertility treatment and it works for small pieces of tissue and blood vessels. Earlier this year, scientists managed to cryogenically freeze the brain of a rabbit and recover it in an “excellent” state – although it is not clear if the brain’s functions would have been preserved as well as its superficial appearance. However, even vitrifying larger structures, such as human kidneys for transplantation, has never been done clinically and remains some way off.

Barry Fuller, a professor in surgical science and low temperature medicine, at University College London, said: “There is ongoing research into these scientific challenges, and a potential future demonstration of the ability to cryopreserve human organs for transplantation would be a major first step into proving the concept, but at the moment we cannot achieve that.”

What is the second advance?

This is the growing appreciation that our personality, skills and memories are to some extent defined by the connections between neurons. This has led some to speculate that rather than bringing the actual body back to life, the brain’s contents could be “downloaded” on to a computer, allowing the person to live as a robot in the future.

This might have the whiff of nonsense, but Nick Bostrom, a professor of philosophy at the University of Oxford’s Future of Humanity Institute, and his colleague, Anders Sandberg, are both banking on this possibility. “As a head, my life would be limited, but by then we will be able to make real connections to computers,” Anders said in a 2013 interview. “So my hope is that, once revived, my memories and personality could be downloaded into a computer.”

However, many neuroscientists have pointed out that even if you could code the astronomical number of connections between the brain’s 100bn neurons, even this would not capture the full complexity of the human mind.

So should I get my body preserved?

From a purely scientific perspective, your money is probably better spent while you are still alive.