The successful "banking" of whole ovaries is the latest of a long line of developments in reproductive medicine that promises to revolutionise the way couples have babies.
Experimental transplantion of frozen ovaries could lead to the development of human ovary banks to restore the fertility of menopausal women, according to scientists.
Previous attempts at transplanting strips or slices of frozen ovarian tissue have successfully restored fertility in animals but resulted in only limited success in humans.
Margaret Lloyd-Hart, a professional dancer from Arizona who was the first woman to have a transplant of frozen ovarian tissue, had to rely on hormone replacement therapy to treat her premature menopause. She remained infertile.
Freezing the entire ovary rather storing strips or slices of tissue is believed a better way of preserving the organ's complement of eggs as well as maintaining its important physiological role in producing female sex hormones.
Past experiments with freezing whole organs – whether they are kidneys or ovaries – have failed because of the difficulty in ensuring that the protective chemicals used in the process are able to penetrate all the tissues and cells.
Researchers led by Professor Roger Gosden, the scientific director of the Jones Institute for Reproductive Medicine at the Eastern Virginia Medical School in Norfolk, Virginia, overcame that difficulty using a subtle method of gently freezing and thawing the entire ovary and its blood vessels.
Being able to freeze ovarian tissue is crucial to restoring the fertility of young women and pre-pubescent girls who have to undergo medical treatment, such as chemotherapy, that causes sterility.
"We really want to transplant as much of the original tissue as possible, preferably the whole organ. So I feel the strips of tissue are really going to work best with children where there is a very big reserve of eggs which would compensate for any losses that would occur," Professor Gosden said. "When it comes to women who are reproductively older, say in their thirties or more, I don't think we can ever expect to have long-term function so, for those cases particularly, the idea of transplanting the whole organ is most attractive," he said.
"This is the first time this has been done reproducibly in a whole organ. I think it works in the ovary partly because we've used a very mild, gentle technique for getting the protective agents and chemicals into the tissue and secondly, perhaps more importantly, the ovary is a very forgiving tissue," added Professor Gosden.
One potential use of the technique if it proves to be reasonably safe and effective is for healthy young women to take the decision to store one of their ovaries in their twenties with a view to having it transplanted back again in their forties.
"Let's say that in the future we had a technique that worked near perfectly – you could imagine that a woman in her twenties who was having another operation may elect to have one ovary removed," Professor Gosden said. "We know that her cycles would continue to be of normal regularity and her fertility would be virtually unimpaired. So she wouldn't notice the difference of having only one ovary," he said.
"That existing ovary could be replaced by the one that was frozen by connecting up the blood vessels. We can assume she would have another 20 years of cyclical function with that ovary. Her eggs would be biologically younger than her 45-plus years," he said.
Professor Gosden concluded: "People talk about egg banking at the moment but this is not very efficient so we are talking about ovary banking, which is at the very early stages of development."Reuse content