Fertility hope for chemotherapy patients

Scientists in the US have become the first to produce a viable human embryo using an egg collected from ovarian tissue that had been kept in frozen storage. Dr Kutluk Oktay and colleagues from Cornell University Weill Medical College published their research in the early online version of The Lancet journal this week. Dr Oktay has been at the forefront of research in this area: in 1999 he was part of a team that was the first to successfully transplant ovarian tissue that had been frozen, and in 2000, in another experiment, the team successfully retrieved eggs from a second woman, although this did not result in pregnancy.

The research team took ovarian tissue from a 30-year old woman before she underwent cancer treatment that rendered her sterile. Six years later, the team thawed the stored tissue, then implanted 15 ovarian pieces beneath the skin of the woman's abdominal wall. The team continued to monitor oestrogen levels in the woman's blood, and gave her drugs to stimulate ovulation. Over a period of eight months, they were able to collect 20 eggs. Eight were of good enough quality to be fertilised, which was done using her husband's sperm. Only one of the fertilised eggs developed as normal, and underwent cell division to develop into an four-celled embryo. This was implanted into the woman's uterus, although no pregnancy resulted.

Dr Oktay's team, which have so far collected and stored ovarian tissue from 50 cancer patients, says that the experiment demonstrates that ovarian function and therefore fertility 'can be preserved in women by long-term ovarian banking'. The study concludes: 'Even though the final proof of success of ovarian cryopreservation and transplantation procedure will be a viable pregnancy in human beings, with the development of a human embryo, prospects for a pregnancy and live born are now more promising'. The team will now try again to achieve a pregnancy in the same woman.

In a commentary published alongside the Lancet article, Dr Johan Smitz, from the Free University of Brussels, Belgium, said that all patients should be made aware that the ovary freezing technique is 'still experimental' and that 'meticulous medical attention' should be paid to any children born.

Meanwhile, a team based at Oregon Health and Sciences University in the US has published details of the first monkey born using an egg taken from transplanted ovarian tissue. The breakthrough, first announced at a conference last year, is published in the journal Nature.