Ovarian Cortical Tissue Is Cryopreserved for Future Fertility

NIAGARA-ON-THE-LAKE, Ontario, Canada--A new technique is being employed in an attempt to eventually restore the reproductive potential of girls and young women receiving radiotherapy or chemotherapy for cancer. Five families in a study from the United Kingdom have chosen to have ovarian cortical tissue samples removed and frozen prior to cancer therapy.

"With the increasing success in the treatment of childhood leukemia and other cancers, we need to address the long-term problems," Louise Bath, MD, Department of Child Life and Health, University of Edinburgh, said at the 5th International Conference for Long-Term Complications of Treatment of Children and Adolescents for Cancer, hosted by Roswell Park Cancer Institute. "One of the more distressing complications of cancer treatment is the potential loss of fertility," she said.

A Study in Sheep

One method of preserving fertility is to harvest mature eggs from the ovary prior to therapy. However, this option is not feasible for prepubescent girls. A study in sheep showed that cryopreserved strips of ovarian cortical tissue, which contain primordial follicles, could be used to restore fertility.

Eight sheep underwent ovariectomy, and strips of their cortical tissue were frozen. The tissue was later thawed and transplanted back into the sheep. All eight had return of their estrous cycles, and one even became pregnant due to a failed vasectomy on the part of the ram.

The selection criteria for women in the Edinburgh study are age less than 30 years, no previous chemotherapy or radiotherapy, no existing children, a greater than 50% chance of cancer cure, and a greater than 50% risk of ovarian failure from the cancer treatment.

Seven families were approached for this tissue storage option. The mean age of the patients was 12.4 years (range, 1.5 to 14.9 years), and the cancers included Hodgkin’s disease, Ewings sarcoma, extradural ependymoma of the lumbar region, and vaginal rhabdomyosarcoma. Thus far, six families have given informed consent, and five girls have undergone the procedure to save tissue samples.

Using a laparoscopic technique, 6 to 10 strips of ovarian cortex are taken under direct visualization from one ovary. The tissue is manipulated in an aseptic environment and stored in Leibovitz medium with 10% DMSO and 10% autologous serum at less than -135°C in the vapor phase of liquid nitrogen.

Ethical Issues

"There are multiple ethical issues to deal with when considering the collection and storage of this tissue," Dr. Bath said. Informed consent must be obtained, which includes consent for the destruction of the tissue in the event of the child’s death, and the child has to undergo an additional surgical procedure to obtain the tissue. "We make no guarantees that this technique will restore fertility, and ultimately the re-implantation attempt will be the patient’s decision to make, based upon future knowledge and medical techniques," she said. "However, we believe that there is potential to keep the tissue in a viable state for many years, which offers hope to these girls."