Restoration of endocrine function and ovulation after a heterotopic ovarian transplant in the inguinal region of rabbits using a vascular microsurgical technique

Whole Ovary Cryopreservation and Transplantation: A Systematic Review of Challenges and Research Developments in Animal Experiments and Humans

Ovarian tissue cryopreservation and transplantation is the only fertility preservation option that enables both restoration of fertility and resumption of ovarian endocrine function, avoiding the morbidity associated with premature menopause. It is also the only technique available to prepubertal patients and those whose treatment cannot be delayed for life-threatening reasons. Ovarian tissue cryopreservation can be carried out in two different ways, either as ovarian cortical fragments or as a whole organ with its vascular pedicle. Although use of cortical strips is the only procedure that has been approved by the American Society for Reproductive Medicine, it is fraught with drawbacks, the major one being serious follicle loss occurring after avascular transplantation due to prolonged warm ischemia. Whole ovary cryopreservation involves vascular transplantation, which could theoretically counteract the latter phenomenon and markedly improve follicle survival. In theory, this technique should maintain endocrine and reproductive functions much longer than grafting of ovarian cortical fragments. However, this procedure includes a number of critical steps related to (A) the level of surgical expertise required to accomplish retrieval of a whole ovary with its vascular pedicle, (B) the choice of cryopreservation technique for freezing of the intact organ, and (C) successful execution of functional vascular reanastomosis upon thawing. The aim of this systematic review is to shed light on these challenges and summarize solutions that have been proposed so far in animal experiments and humans in the field of whole ovary cryopreservation and transplantation.

Restoration of endocrine function and fertility with orthotopic tubal-ovarian allotransplant as the anatomical-functional unit in rabbits

The aim of this study was to re-establish endocrine and reproductive function in tubal-ovariectomized rabbits using orthotopic tubal-ovary allotransplants (OT-OA). Fifty-five New Zealand White nonconsanguineous rabbits were used and allocated into five experimental groups: Each group comprised donors submitted to right salpingo-oophorectomy that served as the donated allograft. In group 1 no cyclosporin (CsA) was administered and rabbits were submitted to left salpingo-oophorectomy (LSO). Group 2 was the allotransplant group and did not receive CsA. Group 3 was the allotransplant group with CsA. They were submitted to bilateral salpingo-oophorectomy followed by OT-OA. CsA of 10 mg/kg/day was administered to rabbits for the first 21 days and 5 mg/kg/day for the remainder of the study. Group 4 received CsA just as for group 3 and was submitted to LSO. During the study the following were measured: estradiol (E2), progesterone (P4), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and histopathological study of the uteri, tubes, and ovaries. Groups 1, 3, and 4 showed a significant increase in serum E2 and P4 levels corresponding to the second week of gestation, compared to group 2 (p < .05). Group 2 showed a significant increase in serum LH and FSH levels during week 10 compared to serum LH and FSH levels in groups 1, 3, and 4 (p < .05). In group 3, three rabbits did not reject the allotransplant, one rabbit became pregnant, and endocrine function was re-established in two rabbits. It can be concluded that OT-OA together with CsA administration re-establishes endocrine function and fertility.

Successful pregnancy in ovariectomized mice using a combination of heterotopic autotransplantation of ovarian tissues and embryo transfer

Aim:  The present report is the first to show that, after ovariectomy, female mice with autotransplanted ovarian sections can maintain pregnancy after embryo transfer (ET) independent of the transplantation site. Methods:  Three-month-old ICR females were ovariectomized, and sections from their own ovaries were transplanted either under their kidney capsule (KC group) or into a subcutaneous space (SC group) just after ovariectomy. In vitro fertilized blastocysts were transferred into uterine horns of the pseudopregnant mice that had received the transplanted ovarian tissues. Cesarean sections were carried out 17 days after ET to deliver any live fetuses that were present, and the numbers of implantation sites and fetuses were noted. Transplanted ovarian sections were removed and fixed for histological analysis. Results:  Of the 10 mice in the KC group that received 107 blastocysts, two females (20%) became pregnant; they showed 12 implantation sites (11.2%) and produced four pups (3.7%). In the SC group, 101 blastocysts were transferred to eight females, and three females (37.5%) became pregnant; there were seven implantation sites (6.9%), and three pups (3.0%) were born. There were no statistically significant differences between the two groups in any of the parameters evaluated. On histological examination, luteinization and vascularization of the ovarian sections that were transplanted in the pregnant SC and KC females were noted. Conclusion:  The pregnancy and full-term fetal development were obtained in ovariectomized mice using a combination of heterotopic ovarian tissue autotransplantation and transfer of embryos produced by in vitro fertilization.