The cryopreservation of ovarian tissue as a strategy for preserving the fertility of cancer patients

The cryopreservation of ovarian tissue is a promising new method for conserving the fecundity of young cancer patients from the sterilizing effects of chemotherapy and/or radiotherapy. In murine and ovine studies the orthotopic insertion of frozen-thawed ovarian grafts into sterilized hosts has resulted in the birth of healthy offspring. Examination of human ovarian tissue after cryopreservation has shown that substantial numbers of morphologically normal and viable primordial follicles survive freeze-thawing. To date however, there is no efficient procedure for using the frozen-banked tissue to restore fertility to patients with ovarian failure. Autografting at an orthotopic or heterotopic site has the greatest potential for success but there is concern that the technique may reintroduce malignant cells to patients in remission from disease. Follicle isolation from the thawed tissue and growth to maturity in vitro is a preferable option but at present the technique is in its infancy. This review presents past and present research in the field of ovarian tissue cryopreservation and explores the possible strategies by which frozen-banked tissue from cancer patients could be used to restore fertility.