Cryopreservation of human spermatozoa: comparison of two cryopreservation methods and three cryoprotectants

OBJECTIVE: To evaluate the ability of two cryopreservation methods and three cryoprotectants to preserve sperm quality. DESIGN: A prospective clinical study. SETTING: Male infertility clinic at a tertiary healthcare center. PATIENT(S): Twenty infertile men and 10 healthy donors. INTERVENTION(S): In the first experiment, semen was cryopreserved by either the Irvine Scientific method (IS) or the Cleveland Clinic Foundation (CCF) method. In the second experiment, semen was cryopreserved by the IS method and one of three cryoprotectants: TES and Tris yolk buffer, Sperm Freezing Medium, or Enhance Sperm Freeze. MAIN OUTCOME MEASURE(S): Postthaw sperm motility, cryosurvival, and kinematics. RESULT(S): Percentages of postthaw sperm motility and cryosurvival were higher in the IS cryopreservation method compared with in the CCF method (15.94 +/- 9.19 vs. 12.07 +/- 7.31 and 47.42 +/- 17.44 vs. 35.76 +/- 17.56). However, the CCF method resulted in significantly better sperm kinematics. Postthaw motility in the donors and patients was highest in the samples frozen in TES and Tris yolk buffer medium. CONCLUSION(S): The IS method was associated with more flash freezing compared with the CCF method and resulted in better preservation of sperm motility and a higher cryosurvival rate. TES and Tris yolk buffer was most effective at protecting sperm from the negative effects of the cryopreservation process. This may be due to the presence of egg yolk along with glycerol.