Long-term follow-up of vitrified and autografted baboon (Papio anubis) ovarian tissue

STUDY QUESTION: Can vitrified baboon ovarian tissue survive >5 months after autotransplantation and subsequently restore fertility? SUMMARY ANSWER: Our results show that ovarian tissue grafts can survive at least 18 months, but fertility restoration could not be confirmed due to lack of pregnancy. WHAT IS KNOWN ALREADY: Ovarian function in baboons can be re-established after autografting of vitrified-warmed ovarian tissue fragments. STUDY DESIGN, SIZE, DURATION: Ovaries from five adult female baboons were used for this study. Unilateral ovariectomy was performed in each animal, followed by vitrification of ovarian fragments. Orthotopic autotransplantation of the vitrified-warmed ovarian fragments was carried out 1 day after ovariectomy. One month later, the other ovary was removed from each animal and vitrified. The next day, the ovarian samples were warmed and orthotopically autografted. Biopsies of grafted tissues were taken after 12 and 18 months for stromal tissue and follicle evaluation. Control samples were collected before vitrification. PARTICIPANTS/MATERIALS, SETTING, METHODS: After grafting, follicle survival, growth and function and also the quality of stromal tissue were assessed histologically and by immunohistochemistry. Estrogen levels were measured, and cyclicity was monitored. All five animals were mated several times. Male baboons used in the mating experiments were not of proven fertility. MAIN RESULTS AND THE ROLE OF CHANCE: After vitrification, warming and long-term grafting, follicles were able to grow. However, their function may have been negatively affected by vitrification and/or transplantation, as expression of kit ligand and c-kit differed from fresh ungrafted tissue (P < 0.05). Corpora lutea and/or ovulation stigma were observed in grafts, indicating successful ovulation in all the baboons, with estrogen levels comparable to those in adult female baboons. LARGE SCALA DATA: Not applicable. LIMITATIONS, REASONS FOR CAUTION: Despite our promising findings on ovarian function restoration, the vitrification procedure could not be validated. Moreover, male baboons used for mating were not of proven fertility. WIDER IMPLICATIONS OF THE FINDINGS: Our protocol of ovarian tissue vitrification successfully re-established ovarian function in a baboon model of autotransplantation. While more studies are required to determine whether this approach can indeed restore fertility, it may prove an easy way of cryopreserving ovarian tissue with a view to recovering ovarian function. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by grants from the Fonds National de la Recherche Scientifique (FNRS) (C.A.A. is an FRS-FNRS Research Associate; grant 5/4/150/5 awarded to M.M.D.), Fonds Speciaux de Recherche, Fondation Saint Luc, Stichting tegen Kanker (Fondation contre le Cancer), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil; grant #013/14 CAPES/WBI awarded to C.M.L.), Wallonie-Bruxelles International (awarded to C.A.A.), Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq; grant awarded to Sarah R. Scalercio) and donations from the Ferrero family. None of the authors have any competing interests to declare.