title: Clinically applied procedures for human ovarian tissue cryopreservation result in different levels of efficacy and efficiency.
abstract: OBJECTIVE
  Different protocols are being used worldwide for the cryopreservation of human ovarian tissue for fertility preservation purposes. The efficiency and efficacy of the majority of these protocols has not been extensively evaluated, possibly resulting in sub-optimally cryopreserved ovarian tissue. To address the impact of this issue, we assessed the effects of two clinically successful human ovarian tissue slow-freezing cryopreservation procedures on the quality of the cryopreserved tissue.
  
  
  METHODS
  To differentiate between cryopreservation (C) versus thawing (T) related effects, four combinations of these two (A and B) very different cryopreservation/thawing protocols (ACAT, ACBT, BCAT, BCBT) were studied. Before and after cryopreservation and thawing, the percentage of living and morphologically normal follicles, as well as the overall tissue viability, was assessed.
  
  
  RESULTS
  Our experiments revealed that the choice of the cryopreservation protocol noticeably affected the overall tissue viability and percentage of living follicles, with a higher viability after protocol BCwhen compared to AC. No statistically significant differences in tissue viability were observed between the two thawing protocols, but thawing protocol BTrequired considerably more human effort and materials than thawing protocol AT. Tissue morphology was best retained using the BCATcombination.
  
  
  CONCLUSIONS
  Our results indicate that extensive and systematical evaluation of clinically used protocols is warranted.
authors.affiliation: Department of Obstetrics and Gynecology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Lobke
authors.initials: L
authors.lastname: Bastings
authors.affiliation: Department of Obstetrics and Gynecology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Johan R
authors.initials: JR
authors.lastname: Westphal
authors.affiliation: Department of Obstetrics and Gynecology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Catharina C M
authors.initials: CC
authors.lastname: Beerendonk
authors.affiliation: Department of Obstetrics and Gynecology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Ruud L M
authors.initials: RL
authors.lastname: Bekkers
authors.affiliation: Department of Obstetrics and Gynecology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Petra L M
authors.initials: PL
authors.lastname: Zusterzeel
authors.affiliation: Department for Health Evidence, Section Biostatistics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Jan C M
authors.initials: JC
authors.lastname: Hendriks
authors.affiliation: Department of Obstetrics and Gynecology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Didi D M
authors.initials: DD
authors.lastname: Braat
authors.affiliation: Department of Obstetrics and Gynecology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands. Ronald.Peek@Radboudumc.nl.
authors.forename: Ronald
authors.identifier: http://orcid.org/0000-0003-2134-3371
authors.initials: R
authors.lastname: Peek
mesh_terms: D015925:Cryopreservation / Q000379:methods; D005260:Female; D059247:Fertility Preservation; D005615:Freezing; D006801:Humans; D009865:Oocytes / Q000254:growth & development*; D006080:Ovarian Follicle / Q000254:growth & development*; D010053:Ovary / Q000254:growth & development*; D014022:Tissue Survival; D058989:Vitrification
keywords: Cryopreservation; Efficacy; Efficiency; Fertility preservation; Ovarian tissue