Paris. Japanese scientists have created clones of mice with freeze-dried cells, a technique they believe could one day be used to conserve species, without the challenges biobanks face today, according to a scientific study published on Tuesday.
Biobanks flourished around the world to preserve samples of endangered species, with the aim of ensuring their survival through cloning.
These samples, usually sperm or oocyte cells, are often subjected to preservation by cryogenization in liquid nitrogen or at very low temperatures, processes that can be expensive and subject to power outages.
Researchers at Yamanashi University sought to avoid these pitfalls by lyophilizing – which involves removing all the water from a body by drying – somatic cells. That is, all those that are not related to sperm or oocytes.
They lyophilized cells extracted from the tail of mice or from immature female oocytes. Freeze-drying killed the cells and damaged their DNA, but they could be used to create clones of blastocysts, a set of cells that develop into an embryo.
They then extracted stem cells that produced 75 mouse clones. One of them, Dorami, survived a year and nine months. The team also managed to reproduce nine cloned females and three males with normal mice.
The specimens proved to be largely healthy, except for a group obtained from male cells that only produced females.
The fertility of the cloned mice was also lower.
“We think we will be able to reduce abnormalities and increase fertility by looking for freeze-drying protectants and improving drying techniques,” Teruhiko Wakayama, who contributed to the research published in Nature Communications, told AFP.
The success rate of the technique, 0.02%, is still much lower than that of cryopreservation or very low temperature, which range from 2% to 5%.
But Wakayama says the technique is still groundbreaking. The one that allowed the cloning of Dolly, the first cloned sheep in 1996, had required 200 attempts.
In the long term, this technique could “allow genetic materials from all over the world to be conserved economically and safely,” Wakayama points out.
A considerable advantage for developing countries.
The team, a pioneer in freeze-drying, sent freeze-dried mouse sperm to the International Space Station (ISS). That he returned healthy after six years in space and allowed, once rehydrated, to produce mice.
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