Ovary cryopreservation and transplantation for fertility preservation

Abstract

The aim of this review is to summarize the state-of-the-art of ovarian transplantation and cryopreservation. This field has progressed over the last half century from simple animal experiments to sophisticated application in humans. The initial poor results in humans began to improve when a series of nine monozygotic (MZ) twin pairs discordant for premature ovarian failure (POF) underwent ovary transplantation at one center. All of these fresh ovary transplants were successful, resulting in 11 healthy babies in 7 of the 9 recipients. The same surgical techniques were then applied to 3 frozen ovary tissue transplants, up to 14 years after the ovary had been frozen, resulting in 3 more healthy babies. Around the world, the number of healthy babies has now risen to 28. Even ovary allotransplantation is being attempted in the not so uncommon situation where a previous bone marrow donor is now willing to donate ovarian tissue to the same recipient. Recipients routinely reinitiated ovulatory menstrual cycles and normal Day 3 serum FSH levels by 4.5 months. Most conceived naturally (three of them twice or three times from the same graft). The duration of function of fresh ovarian grafts, contrary to initial expectations, indicated minimal oocyte loss from ischemia time. Grafts of just modest portions of ovarian tissue have lasted >7 years. In vitro studies suggest that vitrification of ovarian tissue may be an improvement over the 70% oocyte viability loss from slow freeze.