Scientists Report The First Live Births In Large Mammals After Using Frozen Ovarian Tissue

The team, led by Professor Bruno Salle and Dr Jacqueline Lornage of the Departement de Médecine de la Reproduction at the Hôpital Edouard Herriot in Lyon, reported that from six ewes there had been four pregnancies which had produced three live lambs, one lamb that died shortly after birth and two twins that died after a premature delivery.

Prof Salle and Dr Lornage told the European Society of Human Reproduction and Embryology annual meeting at Lausanne today (Monday 2 July) that they believed this was the first report of live births in large mammals after using ovarian tissue which had been taken from the ewes, frozen and stored, then thawed and grafted back into the same sheep.

Prof Salle said: "These four pregnancies, after frozen ovarian autograft, give immense hope to women who become sterilised by cancer treatments. However we are not ready to try this technique in women yet, as first of all the procedure has to be repeated by ourselves and other researchers, and secondly, we need to discover how long the ovarian graft continues to function."

Prof Salle and his team removed one ovary from each ewe, cut it in half and froze each piece down to –1960C. They were then stored in liquid nitrogen for between one and three months. He said: "The hemi ovarian autografts could be stored for longer if necessary." When they were ready to graft the ovarian pieces back into the ewes they thawed the fragments, incubated them for 30 minutes and then carried out the autograft.

Two to four months after the autografts, tests indicated that the ovaries were functioning normally again, and in the summer of 2000 four of the ewes became pregnant. None of the resulting births has shown any malformations, and Prof Salle believes that it was simply due to chance that three of the lambs died.

This research offers the hope that in the future women who have to undergo treatment for cancer which could damage their ovaries (e.g. chemotherapy or radiotherapy) could opt to have ovarian tissue removed before their treatment and then grafted back again afterwards when they wished to have babies.