DNA Fragmentation Dynamics in Fresh Versus Frozen Thawed Plus Gradient-Isolated Human Spermatozoa

Abstract

The aim of this study was to compare the rate of sperm DNA fragmentation (rSDF; increase of SDF over time) in fresh and gradient isolated frozen–thawed semen samples from male sperm donors of proven fertility. SDF was assessed in the two samples obtained from the same fifteen male donors after 0.5, 1.5, 4.5, 6, 24, 48, and 72 h of incubation in a humidified atmosphere of 5% CO₂ in air at 37°C. Analysis was performed based on chromatin dispersion patterns evaluated using the Halosperm® kit. No significant differences in SDF were obtained when fresh and gradient-isolated frozen–thawed spermatozoa were compared at baseline. However, the rSDF shown by the two samples differed and gradient-isolation selected for sperm subpopulations showing a lower variance for SDF. At the individual level, sperm selection by density gradient purification in frozen–thawed samples did not improve the levels of SDF when compared with the values obtained in fresh samples at baseline.

Keywords:

• gradient isolation
• male factor
• sperm chromatin dispersion
• sperm cryopreservation
• sperm DNA fragmentations

ACKNOWLEDGMENTS

This work was supported by BFU 2007-66340/BFI (Ministerio de Educación y Ciencia, Spain).

Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.