Uterus Cryopreservation in the Sheep: One Step Closer to Uterus Transplantation

Background: Uterus transplantation is the only way for women with no functional uterus to become pregnant. However, the technique is limited by the fact that an aggressive immunosuppression is necessary in order to avoid rejection of the graft. For better chances of finding a matching organ, which would minimize the immunosuppressive therapy, the establishment of cryobanks with a large number of uteri would be helpful. The aim of this study was to evaluate the feasibility to cryopreserve sheep uteri and to review the literature in this exciting new field of uterus cryopreservation and transplantation. Material and Methods: Ten sheep uteri were frozen either with slow cooling after perfusion with 10% dimethylsulfoxide, or without perfusion and the contractile ability was compared with that of fresh uteri. Results: All perfused uteri showed contractions after thawing, similar to those of the non-frozen uteri. Conclusion: This study shows that the perfusion of sheep uterus with a cryoprotectant prior to slow freezing allows the cryopreservation of the whole organ and maintains the functionality of the organ after thawing. The perfused sheep uterus provides an experimental model for further investigations with other cryoprotective agents and freezing protocols. Transplantation of the ovaries and uterus has gained new attention recently, since cancer treatment has become more successful at the cost of fertility loss (1, 2). In recent years, the field of cryopreservation of ovarian tissue has experienced a rejuvenation, after the first child birth following retransplantion of cryopreserved human ovarian tissue (1). More than 50 cases of transplantation of fresh and frozen ovarian tissue have been reported, mainly for premature ovarian failure (3-11). The practical utility of uterine transplants has not been established, but is now being investigated for possible applications for patients with congenital absence of the uterus (Mayer-Rokitansky-Kuster- Hauser syndrome), patients having had hysterectomy for benign and malignant uterine or cervical diseases, and patients with intrauterine adhesion (3, 6).