title: Safeguarding Fertility With Whole Ovary Cryopreservation and Microvascular Transplantation: Higher Follicular Survival With Vitrification Than With Slow Freezing in a Ewe Model.
abstract: BACKGROUND
  In young women, ovarian cortex cryopreservation before gonadotoxic chemotherapy and its avascular grafting after cancer healing permitted fertility restoration. However, ischemia reduced the grafts' lifespan. Microvascular transplantation of cryopreserved whole ovary may allow immediate revascularization, ensuring better fertility preservation, but the best cryopreservation method is unknown. We aimed to compare slow freezing and vitrification of whole ovary for fertility preservation purposes, in an ewe model.
  
  
  METHODS
  Twelve ewes were allocated at random to slow freezing (n = 6) or vitrification group (n = 6). Ewes' left ovary was removed and cryopreserved. Dimethyl sulfoxide 2 M was used as cryoprotector for slow freezing. Vitrification was obtained using increasing concentrations of a vitrification solution of the latest generation (VM3) and gradual temperature lowering to minimize toxicity. After a month, the right ovary was removed, the left ovary was thawed/warmed, and its vessels were anastomosed to the right pedicle. Fertility and ovarian function were assessed for 3 years. Ovarian follicles in native and transplanted ovaries were counted and compared at study completion.
  
  
  RESULTS
  Hormonal secretion resumed in all ewes of both groups. One ewe of the slow-freezing group delivered healthy twins 1 year 9 months and 12 days after transplantation. Estimated whole follicle survival was very low in both groups but significantly higher after vitrification than after slow freezing (0.3% ± 0.5% vs 0.017% ± 0.019%, respectively; p < 0.05).
  
  
  CONCLUSIONS
  Further progress is needed before whole-ovary cryopreservation can be considered an option for safeguarding fertility. Whole ovary vitrification provides better follicular survival compared to slow freezing and may be a valuable cryopreservation option.
authors.affiliation: 1 INSERM U846, Stem-cell and Brain Research Institute, Bron, France. 2 Laboratory of Medicine and Biology of Reproduction, Claude Bernard University, Lyon, France. 3 UFR des Sciences de la Santé Simone Veil, Versailles Saint Quentin en Yvelines University, Montigny-le-Bretonneux, France. 4 Department of Reproductive Medicine, Hôpital Femme Mère Enfants, Bron, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Torre
authors.forename: Delphine
authors.initials: D
authors.lastname: Vertu-Ciolino
authors.forename: Claire
authors.initials: C
authors.lastname: Mazoyer
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Selva
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Lornage
authors.forename: Bruno
authors.initials: B
authors.lastname: Salle
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D005260:Female; D059247:Fertility Preservation / Q000379:methods*; D006085:Graft Survival; D050498:Live Birth; D055806:Microvessels / Q000637:transplantation*; D023421:Models, Animal; D006080:Ovarian Follicle / Q000637:transplantation*; D010053:Ovary / Q000098:blood supply* / Q000378:metabolism / Q000637:transplantation*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D020127:Recovery of Function; D012756:Sheep; D013997:Time Factors; D058989:Vitrification
chemical_list: D015415:Biomarkers; D003451:Cryoprotective Agents; D011374:Progesterone; D004121:Dimethyl Sulfoxide