Cryopreservation of Human Ovarian Tissue

Abstract

Cryopreservation of human ovarian tissue would benefit women who are likely to lose their ovarian function because of chemo- or radiotherapy or due to genetic disorders or other causes. In animal experiments, it has been studied for sixty years. For human fertility preservation it started in 1996. Slow programmed freezing was first established. It has become a standard method to be offered to women facing premature ovarian failure. Several protocols and cryoprotectants have been used, most frequently propanediol combined with sucrose, ethylene glycol or dimethylsulfoxide. Functional recovery of frozen-thawed tissue has been shown in ovarian follicle cultures and xenotransplantation. Several healthy infants have already been born after orthotopic transplantation of frozen-thawed tissue to cured women. In vitro follicle culture methods for women who have a risk of re-introduction of malignancy, are under development. A more recent cryopreservation method is vitrification using a combination of cryoprotectants. It has been functional in animal experiments, and the recent results with human ovarian tissue look very promising even though vitrification has so far not been used in human transplantation. Freezing of isolated ovarian follicles is an option which has been studied. Whole ovary freezing with a vascular pedicle which enables vascular anastomosis at transplantation, is a challenging new experimental method.