title: Alginate beads as a tool to handle, cryopreserve and culture isolated human primordial/primary follicles.
abstract: BACKGROUND
  One major concern of grafting cryopreserved ovarian tissue to restore fertility in cancer patients is the possibility of reintroducing tumor cells. Cryopreservation of isolated primordial/primary follicles (PFs) may circumvent this problem. The aim of our work was to compare dimethyl sulfoxide (ME2SO) and ethylene glycol (EG) as cryoprotectants (CPAs) for slow-freezing of isolated human PFs in alginate.
  
  
  METHODS
  Ovarian biopsies from four women were processed for follicle isolation. PFs were embedded in alginate (5-15 per group). Follicles were frozen-thawed using 1.4M ME2SO or 1.5M EG as CPAs. Fresh and cryopreserved isolated follicles were in vitro cultured (IVC) for 7 days. At different time periods (after isolation, cryopreservation and IVC), follicles were evaluated with live/dead assay (using fluorescent probes) and diameter measurement. Follicle viability was calculated according to the percentage of dead follicular cells and the presence of a live/dead oocyte.
  
  
  RESULTS
  A total of 841 PFs were isolated, embedded in alginate and cryopreserved with ME2SO (n=424) or EG (n=259), or used as controls (n=158). After 7 days of IVC, a significant increase in follicle size was observed in the fresh and ME2SO groups, but not in the EG group. The percentage of totally viable PFs was not significantly different before or after seven days of culture in fresh (100% and 82%) or ME2SO (93.2% and 85.1%) tissue. The EG group showed significantly lower viability before (63.9%) and after IVC (66.2%) than the fresh and ME2SO groups.
  
  
  CONCLUSIONS
  Our results show that 1.4M ME2SO yields better preservation of isolated PF viability after thawing and 7 days of IVC than 1.5M EG. Alginate constitutes an easy, safe hydrogel matrix to handle and cryopreserve isolated human follicles using ME2SO as a CPA.
authors.affiliation: Department of Gynecology, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, 1200 Brussels, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Camboni
authors.forename: A
authors.initials: A
authors.lastname: Van Langendonckt
authors.forename: J
authors.initials: J
authors.lastname: Donnez
authors.forename: J
authors.initials: J
authors.lastname: Vanacker
authors.forename: M M
authors.initials: MM
authors.lastname: Dolmans
authors.forename: C A
authors.initials: CA
authors.lastname: Amorim
mesh_terms: D000328:Adult; D000464:Alginates / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D019855:Ethylene Glycol / Q000494:pharmacology*; D005260:Female; D005615:Freezing; D020723:Glucuronic Acid / Q000494:pharmacology; D006603:Hexuronic Acids / Q000494:pharmacology; D006801:Humans; D006080:Ovarian Follicle; D055815:Young Adult
chemical_list: D000464:Alginates; D003451:Cryoprotective Agents; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D019855:Ethylene Glycol; D004121:Dimethyl Sulfoxide