title: Restoration of ovarian function and natural fertility following the cryopreservation and autotransplantation of whole adult sheep ovaries.
abstract: OBJECTIVE
  Is it possible to restore ovarian function and natural fertility following the cryopreservation and autotransplantation of whole ovaries, complete with vascular pedicle, in adult females from a large monovulatory animal model species (i.e. sheep)?
  
  
  CONCLUSIONS
  Full (100%) restoration of acute ovarian function and high rates of natural fertility (pregnancy rate 64%; live birth rate 29%), with multiple live births, were obtained following whole ovary cryopreservation and autotransplantation (WOCP&TP) of adult sheep ovaries utilizing optimized cryopreservation and post-operative anti-coagulant regimes.
  
  
  BACKGROUND
  Fertility preservation by WOCP&TP requires successful cryopreservation of both the ovary and its vascular supply. Previous work has indicated detrimental effects of WOCP&TP on the ovarian follicle population. Recent experiments suggest that these deleterious effects can be attributed to an acute loss of vascular patency due to clot formation induced by damage to ovarian arterial endothelial cells.
  
  
  METHODS
  Study 1 (2010-2011; N = 16) examined the effect of post-thaw perfusion of survival factors (angiogenic, antioxidant, anti-apoptotic; n = 7-8) and treatment with aspirin (pre-operative versus pre- and post-operative (n = 7-9)) on the restoration of ovarian function for 3 months after WOCP&TP. Study 2 (2011-2012; N = 16) examined the effect of cryoprotectant (CPA) perfusion time (10 versus 60 min; n = 16) and pre- and post-operative treatment with aspirin in combination with enoxaparine (Clexane(®); n = 8) or eptifibatide (Integrilin(®); n = 8) on ovarian function and fertility 11-23 months after WOCP&TP.
  
  
  METHODS
  Both studies utilized mature, parous, Greyface ewes aged 3-6 years and weighing 50-75 kg. Restoration of ovarian function was monitored by bi-weekly blood sampling and display of behavioural oestrus. Blood samples were assayed for gonadotrophins, progesterone, anti-Müllerian Hormone and inhibin A. Fertility restoration in Study 2 was quantified by pregnancy rate after a 3 month fertile mating period and was confirmed by ultrasound, hormonal monitoring and live birth. Ovarian function was assessed at sacrifice by ovarian appearance and vascular patency (Doppler ultrasound) and by follicular histology.
  
  
  RESULTS
  In Study 1, survival factors were found to have no benefit, but the inclusion of pre-operative aspirin resulted in four ewes showing acute restoration of ovarian function within 3 weeks and a further six ewes showing partial restoration. The addition of post-operative aspirin alone had no clear benefit. In Study 2, combination of aspirin with additional post-operative anti-coagulants resulted in total acute restoration of ovarian function in 14/14 ewes within 3 weeks of WOCP&TP, with 9/14 ewes becoming pregnant and 4/14 giving birth to a total of seven normal lambs. There was no difference between anti-coagulants in terms of restoration of reproductive function and fertility. In contrast, the duration of CPA perfusion was highly significant with a 60 min perfusion resulting in ovaries of normal appearance and function with high rates of primordial follicle survival (70%) and an abundant blood supply, whereas ovaries perfused for 10 min had either resorbed completely and were vestigial (7/14) or were markedly smaller (P < 0.01). It is concluded that both the degree of CPA penetration and the maintenance of post-operative vascular patency are critical determinants of the success of WOCP&TP.
  
  
  CONCLUSIONS
  Before application of this technology to fertility preservation patients, it will be critical to optimize the CPA perfusion time for different sized human ovaries, determine the optimum period and level of anti-coagulant therapy, and confirm the normality of offspring derived from this procedure.
  
  
  CONCLUSIONS
  This technology holds promise for the preservation of fertility in women. It could also potentially be applied to the cryopreservation of other reproductive or even major organs (kidneys) where there are considerable difficulties in storing donated tissue.
  
  
  BACKGROUND
  Funding was received from the Medical Research Council, University of Nottingham. The authors confirm that they have no conflict of interest in relation to this work.
authors.affiliation: Division of Child Health Obstetrics and Gynaecology, School of Medicine, University of Nottingham, Nottingham NG7 2UH, UK bruce.campbell@nottingham.ac.uk.
authors.forename: B K
authors.initials: BK
authors.lastname: Campbell
authors.affiliation: Division of Child Health Obstetrics and Gynaecology, School of Medicine, University of Nottingham, Nottingham NG7 2UH, UK.
authors.forename: J
authors.initials: J
authors.lastname: Hernandez-Medrano
authors.affiliation: Division of Child Health Obstetrics and Gynaecology, School of Medicine, University of Nottingham, Nottingham NG7 2UH, UK.
authors.forename: V
authors.initials: V
authors.lastname: Onions
authors.affiliation: Division of Child Health Obstetrics and Gynaecology, School of Medicine, University of Nottingham, Nottingham NG7 2UH, UK.
authors.forename: C
authors.initials: C
authors.lastname: Pincott-Allen
authors.affiliation: Division of Child Health Obstetrics and Gynaecology, School of Medicine, University of Nottingham, Nottingham NG7 2UH, UK.
authors.forename: F
authors.initials: F
authors.lastname: Aljaser
authors.affiliation: School of Chemistry, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: J
authors.initials: J
authors.lastname: Fisher
authors.affiliation: MRC Centre for Reproductive Health, University of Edinburgh, Edinburgh EH16 4TJ, UK.
authors.forename: A S
authors.initials: AS
authors.lastname: McNeilly
authors.affiliation: Division of Animal Science, School of Biosciences, University of Nottingham, Nottingham LE12 5RD, UK.
authors.forename: R
authors.initials: R
authors.lastname: Webb
authors.affiliation: Reproduction and Early Development, Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: H M
authors.initials: HM
authors.lastname: Picton
mesh_terms: D000818:Animals; D054304:Anti-Mullerian Hormone / Q000097:blood; D000925:Anticoagulants / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D015925:Cryopreservation; D004359:Drug Therapy, Combination; D017984:Enoxaparin / Q000627:therapeutic use*; D005260:Female; D005298:Fertility / Q000502:physiology*; D059247:Fertility Preservation / Q000379:methods; D006062:Gonadotropins / Q000097:blood; D006080:Ovarian Follicle; D010053:Ovary / Q000502:physiology / Q000637:transplantation*; D011247:Pregnancy; D018873:Pregnancy Rate; D011374:Progesterone / Q000097:blood; D012756:Sheep; D014021:Tissue Preservation / Q000379:methods; D014182:Transplantation, Autologous
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D006062:Gonadotropins; D011374:Progesterone; D054304:Anti-Mullerian Hormone; D001241:Aspirin
keywords: cryopreservation; fertility restoration; ovary; vascular pedicle