How Can Cryoconservation Save Earth's Species From Extinction?

Nature's SAFE are trying to keep endangered animals “alive” by freezing their tissues at –196°C.


Rachael Funnell


Rachael Funnell

Writer & Senior Digital Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Writer & Senior Digital Producer


By storing frozen samples, Nature's SAFE hope to safeguard species from extinction. Image courtesy of Chester Zoo

This article first appeared in Issue 3 of our free digital magazine CURIOUS.  

Conservationists based at the UK’s Chester Zoo announced earlier this year that they have begun freezing tissue samples of the world’s rarest animals in an attempt to safeguard them from extinction. Here, Nature’s SAFE (one of Europe’s largest “living biobanks”) was founded by scientists to create a store of cell lines that can be brought back as living tissue. Once back from the “dead”, these cells could be developed and deployed in breeding programs to try and return a deceased animal’s genetic material into a population.


To find out more about this futuristic approach to conservation, IFLScience spoke to Dr Sue Walker and Dr Rhiannon Bolton, cofounders of Nature’s SAFE, to find out more about how the living biobank actually works, and what species have been given the unusual deep freeze treatment so far.

How does Nature’s SAFE use cryoconservation?

SW: What we do at Nature’s SAFE is basically, if an animal passes away, we can take tissue from their ear which has a large number of fibroblast cells in it. And then, years or months later, we can take them out of the tank and grow those cell lines again. The goal, in theory, is to one day be able to grow whichever cells you want from a cell line including oocytes and sperm… and these could one day be used for artificial insemination. So, all of this is about banking material that might have a use going forward.

What are the main benefits of the cryoconservation approach over existing methodologies?


RB: A lot of biobanks freeze their samples at −20°C [−4°F] and those samples are super important for conservation research, genetic analysis, and things like that. But when you freeze a tissue at −20°C, the water within the cells explodes and it breaks the cell membrane. So, those tissues die.

We use a cryoprotectant and store our cells at −196°C [−320°F]. When you thaw them out, they are still viable, and the DNA is still intact. They're basically alive still. That's what enables us to do further things with the genetic material. We can do cell cultures or transform them into induced pluripotent stem cells. That's the key difference, that we're a living biobank.

The Victoria crowned pigeon is one of several species to have already received the cryoconservation treatment. Image credit: cp2studio /

Are there any cells that can’t be stored like this?

RB: I don’t believe there are, no, but we don’t store every cell. We store eggs, ovarian tissue, testicular tissue, and somatic cells. We mostly get that from a sample of the ear, which contains cartilage and skin and includes fibroblast cells that are very easy to grow. But for different taxa it’s sometimes recommended to take different samples from the cadaver to get the best cell types for storage. So, for example, for fish they actually recommend gills.


SW: We’re still learning which bits are the best, which sounds harsh, but Nature’s SAFE is a very science-based organisation, so we want to make sure we’re making the right decisions based on evidence. So, we’re very slowly starting our research program up and we’ve partnered with Professor Suzannah Williams at the University of Oxford. She is helping us in terms of looking specifically at how to preserve ovarian tissue and then how best to bring that tissue back.

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How do you cope working at temperatures of −196°C?

SW: We have to be suited and booted, wearing special protective equipment. Working with liquid nitrogen also presents its own risks. You can minimize those with gloves and goggles that would normally come in a lab. You’re absolutely safe working with it, you just have to be very careful.

How do you choose species for cryoconservation?


SW: We don't usually choose them because we bank material from animals who have passed away naturally, from natural causes. So, we take samples opportunistically, and we will put them into our living biobank. What we're then trying to do is kind of give those cells or that individual and their genetics life after death, if you like. It gives us an opportunity to bring those genetics back into the population.

However, we're also starting to do a body of work to look at how we could strategically make wildlife samples. This is going to be a PhD that we have coming up very soon, it'll be advertised. And it's going to look at how we could strategically bank for populations that are most at risk, and how we could get those samples. Because we can't always afford to wait for individuals to pass away to get them.

What kind of animals do you have banked currently?

RB: We’ve got all sorts: African wild dogs, jaguars, cheetahs, onagers. There’s lots of birds including the Victorian crowned pigeon. Then there’s mountain chicken frogs, which is super exciting because they’re terribly endangered.


How might these biobanked samples one day help these species?

SW: We’ve actually got two proofs of concept as to how this can help: one is the black-footed ferret; I don’t know if you’ve heard of Elizabeth Ann? Another is the Przewalski’s horse. But it’s exactly the same kind of idea. It’s about looking at these at-risk populations and determining how we can support them genetically.

What’s the ultimate goal?

RB: Preventing extinction! That’s the whole point. I think we have a duty to do something. We’ve made quite a big mess and we’re losing the genetics [of species] every day. If we don’t do something today, even if the technology isn’t 100 percent there yet, if we don’t collect the samples and store them in a way that means they can be reused in the future, then they’re just gone. We’re going to lose so many different species otherwise, so that’s my hope. And, having a young family, I want to make sure that there will still be elephants for [my sons].


SW: We’ve got a long way to go and if we don’t bank it now, we’ve lost hope and we’ve lost that chance. So, right now, it’s about establishing our network and bringing in samples. And at the same time, in parallel, developing and perfecting our techniques to bring that tissue back to life.

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  • animals,

  • conservation,

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  • conservation biology,

  • species conservation,

  • Chester Zoo,

  • conservation efforts,

  • cryopreservation