London - A breakthrough in the treatment of infertile women could soon emerge from work in Japan where scientists have generated viable egg cells from skin tissue.

The study opens the way to helping women to have their own babies even if they have defective ovaries or have been through the menopause.

A team from Kyoto University announced recently that they had used stem-cell technology to create viable egg cells in laboratory mice that were fertilised by IVF to produce normal, healthy offspring.

Although there are still major technical and ethical hurdles to using the same techniques on human cells, researchers are confident that the study brings science a step closer to producing fertile egg cells from the skin cells of women.

It is the first time scientists have created viable egg cells and healthy offspring from a mammal using stem-cell technology, where ordinary cells are converted into stem cells that are then coaxed into becoming mature oocytes, or egg cells, that are fertilised by IVF.

The study was carried out by the same researchers who showed last year it was possible to generate viable sperm cells in a similar manner by converting skin cells of a mouse into stem cells.

Katsuhiko Hayashi of Kyoto University, who is the first author of the study to be published in the journal Science, said the egg cells created in the experiment produced healthy mouse offspring which went on to produce their own healthy offspring.

“They grow normally in terms of body weight and size. They have a normal pattern of genomic imprinting [the way genes are inherited] and they are fertile: they generate pups with comparable size of the litter,” Dr Hayashi said.

“But it is impossible to adapt immediately this system to human cells, due to not only scientific reasons but also ethical reasons,” he said.

The researchers generated the egg cells using two different methods. The first involved taking stem cells from mouse embryos and culturing them in a broth of chemicals and growth factors to become mature egg cells.

The second method involved genetically engineering the same kind of embryonic skin cells to produce eggs using a technology known as induced pluripotent stem cells (iPSCs).

Evelyn Telfer of Edinburgh University, who was not involved in the study, said the work was a remarkable follow-up from the team's earlier work on producing viable sperms cells from skin cells. “It is a quite brilliant study. To be able to make an oocyte from scratch, as it were, really is incredible,” Dr Telfer said.

However, she added, it will be important to replicate the work using skin cells taken from adult mice rather than mouse embryos, which would be more applicable to humans.

Robert Norman, professor of reproductive medicine at the University of Adelaide in Australia, said the breakthrough offered hope for infertile women who wanted to have their own, genetically-related children.

“[It] offers light to those who want a child who is genetically related to them by using personalised stem cells to create eggs that can produce an offspring that appears to be healthy,” Professor Norman said. - The Independent