Doctors in Denmark have succeeded in producing a two-cell embryo after ovarian tissue was removed, frozen, and then thawed and replaced two years later. It is believed that this is the first time a European group has succeeded in creating an embryo in this way.
Dr Claus Yding Andersen told the 20th annual conference of the European Society of Human Reproduction and Embryology: “It is only a matter of time before a woman becomes pregnant and gives birth to a child after having a thawed ovarian transplant.”
In February 2001, Dr Yding Andersen, a doctor and senior researcher at the Laboratory of Reproductive Biology, University Hospital of Copenhagen, Denmark, and his colleagues removed and froze the left ovary of a 32-year-old woman who had been diagnosed with Hodgkin’s lymphoma and was about to receive chemotherapy and radiotherapy.
As a result of the treatment, the patient’s remaining ovary stopped functioning and she became menopausal. In April 2003 the team transplanted six strips from the frozen ovary back to the remaining ovary and eight weeks later ultrasound and tests of hormone levels showed that the ovary was beginning to function again. The woman’s periods resumed.
Since then there have been two unsuccessful attempts to make the woman pregnant. The first involved normal IVF procedures: collecting an egg from the ovary and then using intracytoplasmic sperm injection (ICSI) to fertilize it. However, ICSI failed to fertilise the egg. In the following cycle, the team used intra-uterine insemination (IUI) to try to achieve a pregnancy. This also failed.
However, on 1 June 2004 the team succeeded in creating a two-cell embryo using IVF and ICSI. The embryo was transferred to the woman’s uterus but she failed to become pregnant.
Dr Yding Andersen said: “Recently we transplanted cryopreserved ovarian tissue to another two former cancer patients who also wished to become pregnant. We expect that a pregnancy within our group or another group around the world is likely to happen within the next few years. An American group reported recently that they had produced an embryo after they transplanted back frozen ovarian tissue, but the woman did not become pregnant.”
This method of restoring a woman’s fertility after cancer treatment costs roughly the same as a normal ART cycle. “Replacement of the tissue requires an operation but no other medication is needed in order to resume menstrual cycles. In principle, these women may achieve natural fertility, but I guess that in most cases they will receive ART.”
The possibility that they might be able to have children in the future appears to help the women emotionally. “The woman that we are describing in our presentation has stated that the fact that she had ovarian tissue cryopreserved, was a major factor for her in helping her get through the quite severe chemotherapy that she received. We have heard similar opinions from several of our patients: the fact that they may be able to have children afterwards really helps in combating the cancer,” said Dr Yding Andersen.
Researchers at the Cleveland Clinic Foundation, Cleveland, USA, have succeeded in removing a woman’s ovary and preserving it in its entirety. Professor Mohamed Bedaiwy told the conference that this was the first successful example of this procedure in humans, although the operation had worked in animals already.
Prof Bedaiwy, from the Cleveland Clinic Foundation and Assiut University, Egypt, said: “It raises great hopes for future successful preservation of patients’ ovarian functions during periods when they may be threatened temporarily, for example while undergoing chemotherapy. We are hoping that, in the future, we may be able to re-transplant a functioning ovary into a patient. The procedure may well turn out to be better than egg freezing, which, although promising, has been relatively unsuccessful up to now.”
One operation was performed on a 44-year-old woman who had donated her ovaries for experimental research while she was undergoing vaginal hysterectomy. The ovary was removed together with the vascular pedicle (the attachment which contains the main blood vessels), treated with a protective substance, preserved and frozen in its entirety with a novel method – it was first kept on ice for 30 minutes and only thereafter frozen according to standard protocol. One week later, the ovary was thawed and examination showed it to be viable.
The researchers used a different technique on a 46-year-old woman whose ovary they removed, sectioned and preserved through conventional conservation methods. The results of the procedures suggested that ovarian functioning in the case of autotransplantation of the entire ovary could be more viable than the transplantation of ovarian strips.
One of the problems to date has been that the thawing of frozen ovarian tissue through reperfusion has caused considerable damage to the egg follicles. But this was not apparent in this case, said Prof Bedaiwy, adding that the new procedure bore great promise for patients who are threatened with infertility. “Among the many potential benefits of being able to re-transplant a patient’s own ovary is that it will not be very invasive or traumatic; it will be much simpler than a kidney transplant, for example, but does require micro-surgical experience.”