Fertility Preservation by Ovarian Tissue Banking (Ovarian Tissue Freezing)
Ovarian tissue cryopreservation (freezing) is an experimental method of fertility preservation in which the outer layer of an ovary, which contains a large number of immature eggs, is taken out of the body and frozen for future use. In ovarian tissue freezing process, a part of an ovary or a whole ovary is surgically removed, usually by laparoscopy. In the laboratory, the ovary’s outer layer (called ovarian cortex) is cut into small strips and frozen. An experimental procedure, ovarian tissue freezing is for the most part performed for medically indicated fertility preservation in cancer patients.
When the patient is cured of the primary disease and ready to have children, the ovarian strips are thawed and transplanted back into her body, either on the remaining ovary or elsewhere. In most cases reported in the literature, transplanted ovarian strips regain normal function of producing hormones and eggs. So far, more than 30 live births have been reported worldwide after ovarian tissue freezing and re-transplantation. Likely the most experienced and successful program of ovarian tissue freezing and transplantation is at Sheba Medical Center in Israel. CHR’s FPC follows Sheba protocols for ovarian tissue freezing and reimplantation.
Benefits of Ovarian Tissue Freezing
A major advantage of ovarian tissue freezing is the number of eggs that can be frozen in “one shot.” Embryo freezing and egg freezing typically result in approximately 10 eggs or embryos per freezing attempt. In contrast, ovarian tissue freezing lets women freeze a vastly larger number of immature eggs—hundreds to thousands—for future use. When frozen ovarian tissue is re-implanted into the body and regains its functions, immature eggs that were frozen within the tissue start developing normally, and become retrievable in an IVF procedure.
Unlike egg and embryo freezing, where just one cycle can take a few weeks to complete, ovarian tissue freezing can be performed on very short notice. Even women who must undergo chemotherapy or radiation almost immediately after diagnosis may be able to preserve their fertility using this method.
Ovarian tissue freezing is also an important method of fertility preservation for young girls. When a young girl is diagnosed with cancer or other conditions requiring life-saving, ovary-toxic treatments, the option of egg freezing may not yet be feasible because her eggs have not started the maturation process, which starts with menarche (first menstrual period). While still considered an “experimental” procedure, ovarian tissue freezing is utilized frequently for young prepubescent girls.
Counseling and Informed Consent
Patients considering ovarian tissue freezing should be thoroughly informed about risk-benefit considerations, the procedure’s experimental nature and available alternative treatments. Since ovarian tissue freezing is typically performed for patients facing life-threatening illnesses and ovary-toxic therapies, close communication and coordination among patients, physicians treating the primary disease (oncologists, oncologic surgeons, etc.), fertility specialists performing the fertility preservation procedure and family members is essential. CHR’s Fertility Preservation Center (FPC) is available 24-7, 365 days for emergency consultations involving ovarian tissue freezing.
If you are a potential patient or a physician whose patient potentially requires fertility preservation, please call CHR’s FPC at 212-994-4400.
The Potential of Ovarian Tissue Freezing with In Vitro Maturation
Reproductive medicine is rapidly evolving, and one of the possibilities in this area is to in vitro mature the primordial follicles (very immature eggs) contained in the cryopreserved ovarian tissue. If successful, in vitro maturation (IVM) of primordial follicles would eliminate the need to surgically re-transplant the ovarian tissue back into the body. While IVM is currently not able to mature eggs in such an early stage of development, successful IVM of primordial follicles would make hundreds to thousands of eggs in each small strip of frozen ovary available to cancer survivors later in life, rather than the few dozens currently banked from egg or embryo banking cycles.
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Norbert Gleicher, MD, leads CHR’s clinical and research efforts as Medical Director and Chief Scientist. A world-renowned specialist in reproductive endocrinology, Dr. Gleicher has published hundreds of peer-reviewed papers and lectured globally while keeping an active clinical career focused on ovarian aging, immunological issues and other difficult cases of infertility.