Japanese scientists have successfully produced cloned mice using freeze-dried cells in a technique they believe could one day help preserve the species and overcome challenges with current biobanking methods.
The United Nations has warned of thisAll over the world, at least a million species could disappear due to human-caused effects such as .
Worldwide facilities have been established to preserve specimens of endangered species with the aim of preventing their extinction by future cloning.
These samples are generally cryopreserved with liquid nitrogen or kept at very low temperatures, which can be costly and prone to power outages.
It usually also includesand egg cells, which may be difficult or impossible to harvest from aged or unfertilized animals.
Scientists at Japan’s Yamanashi University wanted to see if they could solve these problems by freezing and drying somatic cells — a cell that is not a sperm or egg cell — and trying to produce clones.
They experimented with two types of mice cells, and found that while freeze-drying killed them and caused significant DNA damage, they could still produce cloned blastocysts — a ball of cells that develop into an embryo.
From these, the scientists extracted the stem cell lines they used to create 75 cloned mice.
One of the mice survived for one year and nine months, and the team also successfully mated cloned female and male mice with inborn partners and produced normal chicks.
Cloned mice produced fewer offspring than would be expected from naturally born mice, and one stem cell line developed from male cells produced only female cloned mice.
“Improvement shouldn’t be difficult,” said Teruhiko Wakayama, a professor in the School of Life and Environmental Sciences at Yamanashi University, who helped lead the study, which was published in Nature Communications this month.
“We believe that in the future we will be able to reduce malformations and increase the birth rate by looking for protective agents from freezing and drying and improving drying methods,” he told AFP.
“We have made a breakthrough in this field”
There are some other drawbacks – the success rate of mice cloning from cells stored in liquid nitrogen or at very low temperatures is between 2 and 5 percent, while the freeze-drying method is only 0.02 percent.
But Wakayama says the technology is still in its early stages, comparing it to the study that produced the famous sheep cloning “dolly” — one success after more than 200 attempts.
“We think the most important thing is that the cloned mice were produced from freeze-dried somatic cells, and that we’ve made significant progress in this area,” he said.
Although this method is unlikely to replace cryopreservation completely, it represents “a very exciting advance for scientists interested in global biodiversity threatened by biobanking,” said Simon Clolo, Senior Research Fellow at the University of Canberra’s Center for Conservation Ecology and Genomics.
“It can be difficult and expensive to work on cryopreservation protocols and so alternatives, especially those that are less expensive and robust, are very welcome,” added Klulu, who was not involved in the research.
The study stored the freeze-dried cells at less than 30 degrees Celsius, but the team had previously shown that the sperm of freeze-dried mice could survive for at least a year at room temperature and they think somatic cells would, too.
This technology could “ultimately allow genetic resources from around the world to be stored cheaply and safely,” Wakayama said.
The work is an extension of years of research on cloning and freeze drying techniques by Wakayama and Associates.
One of their recent projects involved freeze-dried mouse sperm Sent to the International Space Station. Even after six years in space, the cells were successfully rehydrated back on Earth and produced healthy mice.