Measurement of sperm DNA integrity by sperm chromatin dispersion test and TdT-mediated dUTP nick end labeling assay

Abstract

To compare the effects of sperm chromatin dispersion (SCD) test and TdT-mediated dUTP nick end labeling (TUNEL) assay in assessing the DNA fragmentation in human sperm. Motile sperms were isolated from the semen samples obtained from 20 healthy fertile men and 32 clinically infertile patients by swim-up technique, and underwent SCD and TUNEL to analyze the DNA fragmentation. The rate of sperm with DNA damage of the infertile patients was 12.8% +/- 5.8% tested by SCD, significantly higher than that of the healthy fertile men (7.6% +/- 3.3%, t = 3.576, P = 0.001), and the rate of sperm with DNA damage of the infertile patients was 11.1% +/- 5.1% tested by TUNEL assay, significantly higher than that of the healthy fertile men (6.8% +/- 2.8%, t = 3.467, P = 0.001). The proportion of sperm cell with abnormal DNA integrity measured by SCD test was correlated strongly with that determined by TUNEL for the infertile men (r = 0.841, P = 0.000) and for the fertile men too (r = 0.823, P = 0.000). The rate of sperm with DNA damage measured by SCD were not significantly different from those of TUNEL-positive sperm in fertile men (t = 1.996, P = 0.060). The rate of sperm with DNA damage measured by SCD was significantly higher than that measured by TUNEL among infertile patients (t = 3.023, P = 0.005). The presence of sperm DNA damage may lead to male infertility. SCD is simpler, cheaper and more reliable than TUNEL in testing the sperm DNA damage.