Sperm DNA and chromatin integrity in semen samples used for intrauterine insemination

Abstract

Sperm DNA damage is associated with male infertility but whether normozoospermic infertile men also have DNA damage is unknown. To evaluate sperm DNA and chromatin integrity in men with mild male factor infertility. Prospective study of 102 consecutive men (78 normozoospermic, 15 asthenozoospermic, 9 oligozoospermic) enrolled for intrauterine insemination (IUI) and 15 fertile controls. Standard semen parameters and sperm chromatin and DNA integrity were assessed and compared between groups. Sperm chromatin quality was assessed by (1) aniline blue staining (AB is specific to histone lysines), (2) iodoacetamide fluorescein fluorescence (IAF targets free protamine sulfhydryl groups) and (3) sperm chromatin structure assay (SCSA) with the results expressed as % DNA fragmentation index (%DFI). The mean (±SD) percentage of spermatozoa with positive IAF fluorescence was significantly higher in the IUI population compared to fertile controls (17 % ± 10 % vs. 8 % ± 6 %, P = 0.0011) and also in the normozoospermic subset (n = 78) compared to controls (16 % ± 9 % vs. 8 % ± 6 %, P < 0.0001, ANOVA). We also observed a trend toward lower %progressive motility, and higher %AB staining and %DFI in the IUI group compared to controls. We observed significant relationships between sperm %DFI and progressive motility (r = -0.40, P < 0.0001) and between positive AB staining and IAF fluorescence (r = 0.58, P < 0.0001). The data indicate that sperm chromatin integrity may be abnormal in men enrolled in IUI treatment cycles, despite the fact that most of these men are normozoospermic.