Mice cloned from freeze-dried cells

J-STORIES - Researchers at a university in central Japan have developed a new way to preserve genetic material, pathing the way for the protection of even the most endangered species and potentially protecting animals against new diseases and environmental change.

In its search for an alternative to existing methods for storing reproductive cells, such as cryopreservation, the University of Yamanashi scientists developed a simple and inexpensive alternative. Instead of preserving sperm and egg cells using liquid nitrogen, which is cooled to minus 196 Celsius in cryopreservation, the Yamanashi researchers used non-reproductive cells and a freeze-drying and storage method that can take place at the relatively warm temperature of minus 30 degrees, and possibly warmer.

Previously developed techniques focusing on the preservation of sperm and eggs are costly and face particular difficulties when it comes to rare species, where harvesting reproductive cells can harm the animals. The Yamanashi scientists were able to get around this problem by using the somatic cells, which are essentially any cell other than reproductive cells, meaning they can come from virtually any part of an organism.

The four ampules pictured contain freeze-dried cells.      Source: University of Yamanashi — The four ampules pictured contain freeze-dried cells. Source: University of Yamanashi

And the team has put the method to the test tube. As reported in the British science journal, Nature Communications, the university's researchers harvested somatic cells from mice, freeze-dried them and stored them for up to nine months. They then used those cells to create clones, including a mouse with a normal lifespan and the ability to reproduce.

A black female mouse, nicknamed “Dorami,” was cloned using freeze-dried cells. The white mouse is an ordinary male mouse that successfully mated with Dorami.     Source: University of Yamanashi — A black female mouse, nicknamed “Dorami,” was cloned using freeze-dried cells. The white mouse is an ordinary male mouse that successfully mated with Dorami. Source: University of Yamanashi

Sayaka Wakayama, one the University of Yamanashi researchers, explained how somatic cells can be harvested from anywhere in an animal’s body, and even from its feces. Unlike when using reproductive cells, the sex, age and health of the subject make no difference when using somatic cells, she said.“ That means we can preserve genes without harming endangered animals,” she said.

The research team has suggested that the technology might even be a step toward creating clones from the preserved remains of extinct animals, such as Japanese wolves and Japanese otters.

A challenge for the team is to improve the cloning success rate, which is currently only 0.2 percent to 5.4 percent. The team also hopes to be able to store cells at room temperature. That would make it easier to preserve genetic material during natural disasters, or other situations when power is disrupted, which can impact existing methods using liquid nitrogen.

Previously, the team created baby mice from freeze-dried sperm stored at room temperature for over a year, and for around six months on the International Space Station. It has also created clones from somatic cells that were harvested from the body and urine of a dead mouse stored in a freezer for 16 years.

And the technique could have other far-reaching implications. “Some individual living creatures have genes that are not currently in use, such as genes that can resist unknown diseases, or that can withstand heat,” the research group’s leader, Teruhiko Wakayama, told J-Stories. “If we can preserve as many genes as possible, one day we can use the resistant genes to help animals survive new diseases, or environmental change.”