Lab-grown mouse eggs produce healthy babies

Japanese researchers turned skin cells to stem cells which generated eggs suitable for IVF – but there's a long way to go before the technique's used on humans. Anthea Batsakis reports.

Healthy mice were born from eggs that came not from their mother's ovary but from pluripotent stem cells.
Jamie A. MacDonald / Getty Images

Fully functional mouse eggs, grown entirely in a lab, produced healthy baby mice following implantation in a surrogate, a study published in Nature reports.

Scientists from Japan recreated an ovary's egg-growing process with pluripotent stem cells – “master cells” that can turn into any of the 220 specialised cell types in the body, such as skin cells or heart cells – or in this case, reproductive cells.

They underwent in-vitro fertilisation, or IVF, and some of the resulting baby mice – male and females – even went on to have pups of their own.

Using pluripotent cells to create an egg, or ovum, has enormous potential for infertile women, says Hayden Homer from the University of Queensland in Brisbane, Australia.

It means scientists can theoretically produce an ovum from any type of cell in the body.

“Imagine if you could do that in a woman – if you could take a skin cell from them and then ultimately generate an egg,” he says.

“And there's a long, long way to go, but the proof of principle is in the paper.”

So how does it work?

A female egg cell normally develops when germ cells – simple cells in the ovary – divide and replicate to form an immature egg cell called an oocyte. This then develops into a complex egg, which is able to be fertilised.

Kyushu University molecular biologist Katsuhiko Hayashi and a team of researchers took a different route and used shape-shifting pluripotent stem cells to generate eggs.

They started with cells taken from the tip of a mouse’s tail. They turned these specialised cells back to their pluripotent form, then re-wired them to follow a pathway that would lead to an egg.

It’s a technique the team has done before, but this time, they showed it could produce functional eggs and fertile offspring.

For humans, though, “this is a long, long way away from clinical application in any way whatsoever”, Homer says.

For instance, developing the early stages of human egg growth in a cell culture takes two to three months, not two to three weeks as is the case with mice.

In any case, their success has been long sought by scientists, the authors write in their paper. Homer agrees.

“It's a huge amount of work that they went through and it is a remarkable achievement,” he says.

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