Analysis of DNA fragmentation, plasma membrane translocation of phosphatidylserine and oxidative stress in human spermatozoa

The objectives of this cross-sectional observational study were: (i) to det ect DNA. damage and plasma membrane translocation of phosphatidylserine in purified sperm populations of high and low motility; and (ii) to analyse th eir relationship with the endogenous generation of reactive oxygen species. Ejaculates from infertile men were examined following gradient centrifugat ion, The main outcome measures were: sperm motion parameters (assessed with a computer analyser), generation of reactive oxygen species (measured by c hemiluminescence), DNA damage (detected by terminal deoxvnucleotidyl transf erase-mediated dUDP nick-end labelling and monoclonal antibody labelling of single-stranded DNA) and translocation of membrane phosphatidylserine (exa mined with annexin V staining). DNA fragmentation and membrane translocatio n of phosphatidylserine were observed in the fractions with low and high sp erm motility in all patients. The fractions with low sperm motility had sig nificantly higher proportion of cells with DNA damage and production of rea ctive oxygen species than the fractions with high sperm motility (P < 0.005 ). DNA fragmentation was significantly and positively correlated with the g eneration of reactive oxygen species (r = 0.42; P = 0.02), Zn conclusion: ( i) spermatozoa from infertile men display translocation of membrane phospha tidyIserine as diagnosed by annexin V positive staining; (ii) DNA damage (f ragmentation and presence of single-stranded DNA) can be detected in ejacul ated spermatozoa from infertile men in fractions with low and high sperm mo tility, and (iii) there is a relationship between DNA, damage and oxidative stress.