Iodixanol as a density gradient medium for the isolation of motile spermatozoa.

Purpose: The purpose of this study was to establish concentrations of Iodixanol which could be used in a similar manner to the widely used Mini-Percoll technique for the separation of motile spermatozoa.

Methods: Various density gradient combinations of Iodixanol were compared for the isolation of motile spermatozoa from cryopreserved donor semen. The toxicity of Iodixanol was tested by its effect on the growth of two-cell mouse embryos and fresh sperm survival.

Results: The best sperm recovery (32%) came from the pellet of sperm passing through a discontinuous gradient of 25% over 40% OptiPrep after 20 min of centrifugation at 400 g. There was no evidence of toxicity to mouse embryo growth or sperm survival.

Conclusions: Iodixanol (OptiPrep; Nycomed) provides a satisfactory alternative for the efficient separation of motile spermatozoa for ART procedures.