Japanese scientists are using dried cells to clone mice, aiming to prevent the extinction of the animals

Posted by: 07/06/2022 – 15:36

Japanese scientists have created cloned mice using freeze-dried cells, a technique they hope will one day help preserve the species and overcome current challenges in using biobanking methods.

The United Nations had issued a warning Destruction of animals The world is witnessing an acceleration, and at least one million species may disappear due to the effects of human activities such as climate change. To counter this risk, special facilities for preserving specimens of endangered species have sprung up around the world, with the aim of preventing extinction through future cloning.

These samples are typically preserved by cooling with liquid nitrogen, or at very low temperatures, both of which are expensive and prone to power outages. The samples usually include sperm or egg cells, which are difficult or impossible to obtain from old or sterile animals.

A team of scientists from Japan’s Yamanashi University wanted to see if they could overcome these problems by freeze-drying somatic cells, i.e. cells without sperm or eggs, in an attempt to create clones.

Mating and giving birth to cloned mice

The scientists conducted their experiments on cells from two types of mice and found that even though freeze-drying killed them and caused significant damage to their DNA, they were still able to form clonal blastocysts. From these bags, the scientists extracted the stem cell lines used to produce 75 cloned mice.

One of the mice lived a year and nine months, while the scientists successfully married female and male clones from two naturally born mice to produce normal mouse pups. The cloned mice produced fewer offspring than would be expected from naturally born mice, while one of the stem cell lines created from male cells was only produced in cloned female mice.

Teruhiko Wakayama, a professor at Yamanashi University’s College of Life and Environmental Sciences, who helped prepare the study published in the journal, said:Natural communication“In the past month, growth should not be difficult. We believe that by searching for agents that protect against freezing and drying and improving drying methods, we can reduce defects and increase the birth rate in the future.”

For example, cloning mice from cells stored in liquid nitrogen or at very low temperatures has a success rate of 2 to 5 percent, while the freeze-drying technique has a success rate of only 0.02 percent.

Compared to the research work that resulted in the successful cloning of “Dolly” the sheep after more than two hundred attempts, Wakayama found the technique still in its infancy. “The most important thing is that the cloned mice were created from freeze-dried somatic cells, and we have made significant progress in this area,” he said.

Conservation of genetic resources

While the technology is unlikely to completely replace cryopreservation, “this is an important advance for scientists interested in global biodiversity threatened by biobanking methods,” says Simon Clolo, senior research fellow at the University of Canberra’s Center for Environmental and Genetic Conservation. “Cryopreservation protocols can be difficult and expensive to work with, so alternatives, especially those that are less expensive and more efficient, are very welcome,” said Clolo, who was not involved in the study.

The scientists in the study stored the freeze-dried cells at minus 30 degrees Celsius, but they had previously found that freeze-dried mice sperm could survive at room temperature for at least a year, and they believed somatic cells would remain. React in the same way. Wakayama explained that the technology “may eventually allow us to save the entire world’s genetic resources at a lower cost and more safely.”

This research work is an extension of several years of research on cloning and freeze-drying techniques carried out by Wakayama and colleagues. One of their recent researches involved freeze-dried mouse sperm and sent to the International Space Station. Despite six years in space, the cells were successfully rehydrated after returning to Earth, producing healthy young mice.

France 24/AFP