Israeli scientists report (Thursday 15 September) in Human Reproduction that they have successfully transplanted whole frozen and thawed ovaries in sheep, retrieved oocytes from these ovaries and triggered them in the laboratory into early embryonic development.
Follow-up tests showed that the ovaries in the two sheep from which oocytes were recovered were still functioning normally three years later.
Lead author Dr Amir Arav, senior scientist at the Institute of Animal Science, Agriculture Research Organisation, Bet Dagan, said that these results demonstrate for the first time that it is possible in a large animal species, to remove, freeze, thaw and replace ovaries, obtain oocytes and maintain normal ovarian long-term function. This holds out hope that this approach could become a feasible treatment for women facing premature ovarian failure, and furthermore, that the advances they have demonstrated from new freezing techniques may have potential for other human organ transplants, which are currently done using only fresh grafts.
Co-author Yehudit Nathan, program manager at Core Dynamics, the biotech company that funded and provided the scientific and technological expertise for the project, said the next goal was to attempt to transplant ovaries in women at risk of losing their fertility.
"There is a lot of research still to be done, but we hope that it will not take more than a few years for this to become a practicable option for women, such as young cancer patients, who would otherwise be left infertile after their treatment," she said.
Whole ovary autologous transplants have already been attempted twice in women ?in 1987 and 2004 ?in both cases into the upper arm, but in neither case was the ovary frozen and thawed first.
Another much-researched option is freezing and transplanting thawed ovarian tissue. Two babies have been born us
Source:European Society for Human Reproduction and Embryology