Effects of different storage conditions of semen samples on the detection results of sperm DNA damage

Abstract

Standardizing the storage conditions of semen samples can improve the accuracy of detection results of sperm DNA fragmentation index (DFI) and reduce variability. This study aimed to investigate how different storage conditions affect the DFI results of sperm. To do this, thirty-five leftover semen samples were selected after routine testing. These samples had a sperm concentration of at least 10 × 106/mL, normal liquefaction, and no or few round cells. Each specimen was stored at room temperature (20 °C) for 2 and 4 hours, chilled (2–8 °C) for 1, 2 and 3 days, and frozen (−20 °C) for 3, 5 and 7 days, respectively. Each sample was frozen and thawed three times repeatedly. The sperm DFI at different time points was detected by sperm chromatin structure analysis (SCSA) based on flow cytometry. The results showed no significant differences in the sperm DFI of semen samples stored at room temperature for 0, 2 and 4 hours, chilled for 1, 2 and 3 days and frozen for 3, 5 and 7 days (p > 0.05). There were also no significant differences in the sperm DFI of semen samples frozen-thawed 1, 2 and 3 times repeatedly (p > 0.05). In conclusion, storage at room temperature for less than 4 hours, chilling for less than 3 days, freezing for less than 7 days and repeated freezing-thawing for 3 times have no significant impact on the sperm DNA damage of semen samples with sperm concentration ≥10 × 106/mL, normal liquefaction, and no or few round cells found in routine semen examination.

Keywords

• sperm dna damage
• flow cytometry
• sample storage
• freeze-thaw times
• standardization