title: Cryopreservation of spermatozoa in alginic acid capsules.
abstract: OBJECTIVE
  To develop a method of freezing small amounts of spermatozoa in polymerized alginic acid drops, which can be liquified after thawing for recovery of the spermatozoa.
  
  
  METHODS
  Prospective clinical study.
  
  
  METHODS
  Medical School, RWTH Aachen, Aachen Germany.
  
  
  METHODS
  None.
  
  
  METHODS
  Validation of the encapsulation method with bovine sperm; cryopreservation of human spermatozoa in alginic capsules.
  
  
  METHODS
  We optimized the cryopreservation method by testing different parameters influencing the freezing procedure, such as concentration of alginic acid, size of drops, time of polymerization, and culture media.
  
  
  RESULTS
  The final protocol was as follows: encapsulation by 7.3 mg/mL alginic acid forming 10-muL drops polymerized for 30 seconds and liquefied for 2.5 minutes in sodium citrate. Cryopreservation of human spermatozoa by this protocol resulted in a decreased motility of 18.3% compared with standard protocols but a 19.9% higher vitality of the immotile spermatozoa.
  
  
  CONCLUSIONS
  No difference in viability of spermatozoa after both sperm-freezing procedures could be observed. Further investigation will be undertaken to reduce the amount of immotile but viable sperm after microencapsulation in alginic acid.
authors.affiliation: Department of Anatomy and Reproductive Biology, Medical School, RWTH Aachen, Aachen, Germany. aherrler@ukaachen.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Herrler
authors.forename: Sabine
authors.initials: S
authors.lastname: Eisner
authors.forename: Vera
authors.initials: V
authors.lastname: Bach
authors.forename: Ute
authors.initials: U
authors.lastname: Weissenborn
authors.forename: Henning M
authors.initials: HM
authors.lastname: Beier
mesh_terms: D000464:Alginates; D000818:Animals; D001672:Biocompatible Materials; D002214:Capsules; D002417:Cattle; D015925:Cryopreservation / Q000379:methods*; D003470:Culture Media; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006801:Humans; D008297:Male; D009845:Oligospermia / Q000628:therapy; D011446:Prospective Studies; D013081:Sperm Motility; D013094:Spermatozoa / Q000166:cytology*
chemical_list: D000464:Alginates; D001672:Biocompatible Materials; D002214:Capsules; D003470:Culture Media; D006603:Hexuronic Acids; D020723:Glucuronic Acid