Several studies have associated telomere shortening with impaired reproductive function. The aim of this study was to determine the telomere length (TL) in spermatozoa selected by density gradient centrifugation (DGC) or swim-up. TL analysis was performed by quantitative fluorescent in situ hybridization (qFISH) using PNA probes in combination with a sperm chromatin decompaction protocol. The TL results were 24.64 ± 5.00 Kb and 24.95 ± 4.60 Kb before and after DGC, respectively, and 19.59 ± 8.02 Kb and 20.22 ± 5.18 Kb before and after swimming, respectively. Sperm selected by DGC or swim-up did not show significant differences in TL compared to unselected sperm (p > 0.05).
Negative correlations were found between TL and sperm motility (r = -.308; p = .049) and concentration (r = -.353; p = .028). Furthermore, exposure of spermatozoa to increasing concentrations of hydrogen peroxide during incubation resulted in a reduction in TL. These data indicate that oxidative stress may be one of the main factors involved in the reduction of LT in spermatozoa. Preliminary clinical results of the patients included in this study indicate that LT was shorter in sperm from couples who never achieved pregnancy compared with couples who achieved at least one natural pregnancy (p < .05); however, the clinical utility of this biomarker still needs to be confirmed in further studies.
Keywords: male infertility; sperm; telomere.