* "Proof of concept" study restores ovary function in rats
* Experts say findings pave way for possible human treatment
LONDON, Sept 15 (Reuters) - Scientists have found that injecting a particular type of stem cells into infertile female rats can restore the function of their ovaries, and say their findings could pave the way for a similar treatment for humans.
The researchers, led by Osama Azmy of the National Research Centre in Cairo, Egypt, used a type of embryonic rat stem cells known as mesenchymal stem cells (MSCs) to restore ovary function in experimental rats.
"This is proof of concept, and there is still a long way to go before we can apply this to women," Azmy said in a report of the findings, which were presented at the World Congress of Fertility and Sterility in Germany on Wednesday.
"Nevertheless, this work holds out the possibility that women with premature ovarian failure might be able to bear a baby of their own."
About one percent of women under the age of 40 around the world suffer from premature ovarian failure (POF) -- a condition that is often referred to as "premature menopause" in which the normal functioning of the ovaries stops early.
Sufferers generally stop producing eggs and ovarian hormones, and there is as yet no treatment that can restore fertility.
Stem cells are master cells that can develop into any kind of specialised tissue in the body. The potential of different kinds of stem cells is being examined by scientists around the world for many diseases, but the technology is controversial, in part because some stem cell lines are derived from embryos or foetuses.
For their study, Azmy's team used 60 experimental female rats and gave three quarters of them a chemical which induced ovarian failure. They then injected a third of these with the stem cell treatment, injected a third with a salt solution or placebo, and gave another third no treatment at all.
The researchers tested the hormone levels of all the rats to see if they returned to normal following treatment.
Within two weeks, the rats who had been treated with stem cells had regained full ovarian function and after eight weeks their hormone levels were the same as the rats who did not have ovarian failure.
"What we have done is proven that we can restore apparently fully-functioning ovaries in rats. The next step is to look how these rats might reproduce," Azmy said. (Reporting by Kate Kelland, editing by Matthew Jones)