The effect of age on the expression of apoptosis biomarkers in human spermatozoa

Objective: To evaluate the impact of age on the expression of apoptotic biomarkers in human spermatozoa. Design: Cross sectional, prospective study. Setting: Academic centers. Patient(s): Healthy volunteers with proven fertility, stratified by age (n = 25, range: 20-68 years). Intervention(s): Examination of serum hormone levels and basic semen parameters, and assessment of early (plasma membrane translocation of phosphatidylserine) and late (DNA fragmentation) sperm apoptotic markers by flow cytometry (using Annexin-V binding and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling). Main Outcome Measure(s): Apoptosis markers. Result(s): Advancing male age was significantly and positively correlated with Annexin-V binding results. Although not significant, there was a clear trend for increased DNA fragmentation in the older groups. The age threshold for these observations appears to be 40 years. Advancing male age was positively correlated with FSH and sex hormone-binding globulin (SHBG) levels, and negatively correlated with sperm concentration. Conclusion(s): Advancing male age is associated with the expression of early apoptotic markers as evidenced by significantly increased plasma membrane translocation of phosphatidylserine, as well as with a more subtle proportion of sperm carrying DNA fragmentation. This study confirmed that male age is also associated with a decline in sperm concentration.