How freezing-dried mice could be used to conserve species

Japanese scientists have succeeded in creating cloned mice from freeze-dried cells.

05 July 2022 Tuesday 10:22
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How freezing-dried mice could be used to conserve species

Japanese scientists have succeeded in creating cloned mice from freeze-dried cells. This technique could be used to help preserve species and overcome the challenges of current biobanking techniques.

The United Nations warned that global extinctions are increasing and that at least one million species may disappear due to human-caused impacts such as climate change.

Globally, facilities have been set up to preserve endangered species' samples in the hopes of preventing future cloning.

These samples are usually cryopreserved with liquid nitrogen or kept at very low temperatures. This can make them vulnerable to power outages and costly.

These eggs also contain sperm and eggs cells. It can be difficult, or even impossible, to obtain these cells from infertile or elderly animals.

Japan's University of Yamanashi scientists wanted to know if they could solve these problems by freezing somatic cells (any cell that isn’t a sperm cell or egg cell) and trying to make clones.

They tested two types of mice cell lines and discovered that freeze drying killed them and caused DNA damage. However, they were able to produce cloned blastocysts, which are a collection of cells that eventually develop into embryos.

These stem cells were used by scientists to create 75 cloned mice.

One of the mice lived for a year, nine months. The team also succeeded in mating male and female cloned mice with their natural-born partners. Normal pups were produced.

Cloned mice had fewer offspring than expected, and one stem cell line from male cells only produced female mice clones.

Teruhiko Wakyama, a professor at University of Yamanashi's Faculty of Life and Environmental Sciences who led the study that was published in Nature Communications, said, "Improvement shouldn't be difficult."

He told AFP that he believes that we can reduce abnormalities and increase birth rates by looking for freeze-drying protector agents and improving drying methods in the future.

Other drawbacks include the fact that the success rate for cloning mice using cells stored at ultralow temperatures or liquid nitrogen is between 2 to 5 percent and 0.02 percent respectively.

Wakayama claims the technique is still in the early stages. He compares it to the study that created "Dolly", the famous sheep clone, which was a single success after more 200 attempts.

He stated that "cloned mice were produced from freeze-dried somatic cell and that this is a major breakthrough in the field."

Although the method will not completely replace cryopreservation it is a significant advance for scientists who are interested in biobanking threatened biodiversity worldwide," stated Simon Clulow (senior research fellow at the University of Canberra’s Centre for Conservation Ecology and Genomics).

Clulow, who wasn't involved in the research, stated that it can be costly and difficult to create cryopreservation protocols. Therefore, alternatives, especially ones that are more affordable and stronger, are highly welcome."

The cells were frozen at minus 30° Celsius. However, the study previously demonstrated that freeze-dried mouse embryos can survive for at least one year at room temperature. It is also believed that somatic cells could do the same.

Wakayama stated that the technique could allow genetic resources from all over the globe to be stored safely and cheaply.

This work is a culmination of Wakayama's years-long research on freeze-drying and cloning techniques.

Their latest project was to freeze-dry mouse sperm, which was then sent to the International Space Station. The cells survived six years in space and were successfully rehydrated on Earth, producing healthy pups for mice.



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