Thursday, August 11

We just cloned mice with a new technique. It is perhaps a first step to recover extinct species


On March 19, 2018, among armed soldiers protecting his life, the last male northern white rhino died in Kenya’s Ol Pejeta reserve. He was 45 years old and was the last of his extirpation: there were three more females left, but with him the possibility of recovering a species that poachers and traditional medicine had taken until the last breath was extinguished. Or so we thought.

However, the genetic and reproductive battle had only just begun and now a new technique has just opened the door to bring back not only the northern white rhinoceros, but dozens of species that are on the brink of extinction.

What happened? A team of researchers from Yamanashi University in Japan has just created cloned mice from freeze-dried skin cells. Until now, techniques have focused on frozen cells, but preserving biological material in liquid nitrogen is not only expensive, it is highly subject to technical problems. In the face of any problem, the cells break down and become useless.

The search for techniques that would allow clones to be made from freeze-dried cells has been on the table for years because, if achieved, “the genetic resources of the entire world can be stored economically and safely”, explained Professor Teruhiko Wakayama, director of the project.

It was something that completely changed the rules of the game. “Developing countries could store their own valuable genetic resources in their own countries. Furthermore, this technology can be used to create females even in endangered species where only males survive.”

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We believed that we could resurrect extinct species, like in Jurassic Park.  It will be very difficult

How have they done it? The first thing the researchers did was treat skin cells from mouse tails and store them for up to nine months before trying to create clones from them. The lyophilization processes destroyed the cells. However, almost in extremisscientists found that they could still create blastocysts (very early embryos) by inserting the dead cells into mouse eggs that had had their own nuclei removed.

From those blastocysts, stem cells developed and were used to generate new embryos. And these were successfully completed. 75 mice were created and 12 of them were bred to check that fertility was not affected. It wasn’t: all the females had litters of mice.

Many problems…. The achievement is impressive, but the technology is still very clumsy, really. The process is still quite imprecise and the success rate for creating healthy male and female mouse pups was very low (less than 5% were successful). However, the advance paves the way for increasing the genetic diversity of threatened species. We already know that the loss of genetic diversity can also make animals more vulnerable to diseases of all kinds.

…and a hope. The moral of this experiment (if experiments can have morals at all) is that we need less and less to rebuild functional embryonic cells. This is, let’s not forget, a long-distance race that will first prevent species on the verge of extinction from disappearing and, later, will give us enough tools to bring back disappeared species. It doesn’t seem like a good idea to play with that, it’s true; and it will not even be easy to do so, but there is no doubt that it is a door that is about to open.

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Image | Yamanashi University

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