06 July 2009
ByAppeared in BioNews 515
Two studies reported at the annual conference of the European Society for Human Reproduction and Embryology (ESHRE) in Amsterdam last week show advances in ovarian transplant techniques. The advances could make the procedure available to women seeking to avoid fertility problems as they age.
Ovarian transplants have been primarily used as a way to preserve fertility in women undergoing treatments that damage the reproductive system, such as chemotherapy. The ovaries can be removed and frozen before such treatment begins, and then reimplanted after treatment has finished. Previously, it has only been used for women with serious disease; due to the uncertainties involved. Now, advances in the technique mean transplants are more successful, and it may be possible that the procedure can become more widely available.
In the first study Dr Sherman Silber reported that freezing ovarian tissue using vitrification gave the same success rate as using fresh tissue. Freezing ovarian tissue using the vitrification method avoids ice formation, and egg viability was almost identical to that seen in fresh tissue. Dr Silber and colleagues tested the different methods in 15 women undergoing cancer treatment. He explained that 'we found that 91.9 per cent of the fresh oocytes were viable compared with 88.9 per cent of those vitrified. However, slow freezing resulted in a 56 per cent loss of viability.' Transplantation resulted in patients regaining a normal ovarian cycle in about five months, and ovarian function lasted for four years in some of the patients. There were no differences in pregnancy rates or ovulatory menstrual cycling between the fresh and frozen grafts.
In the second related study, researchers in France led by Dr Pascal Piver reported on a technique that may improve success of ovary transplant. The technique is a two-step process, where a very small section is implanted first, and the ovary implanted three days later. This encourages blood flow and hormone supply to be quickly restored to the implanted ovary. This helps the implanted ovary to become functional - something that doctors have previously struggled to do. The procedure is also less invasive than the previous one-step method. Dr Piver reported on the first success of the technique in his clinic, saying: 'On June 22, a baby girl was born to a mother who had been menopausal for two years as a result of treatment for sickle cell anaemia. After transplanting her own ovarian tissue she started ovulating in four months and became pregnant naturally six months after transplantation. Both mother and baby are doing well.'
Experts said the possibility of healthy women being offered ovary transplants may spark controversy. 'This is not an experimental procedure for cancer patients anymore', said Dr Silber, director of the St. Louis Infertility Center in Missouri, US, adding: 'The question is whether more women should be able to have this option.'
'We are in the middle of an infertility epidemic,' he told AP news. 'With these new techniques, we could dramatically expand our reproductive lifespan', he added.