Sperm telomere length in motile sperm selection techniques: A qFISH approach

Abstract

Several studies have associated telomere shortening with alterations in reproductive function. The objective of the present study was to determine telomere length (TL) in spermatozoa selected by either density-gradient centrifugation (DGC) or swim-up. The analysis of TL was performed using quantitative fluorescent in situ hybridisation (qFISH) using PNA probes in combination with a chromatin decompaction protocol in sperm cells. Results of TL 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 swim-up respectively. Sperm selected by DGC or swim-up did not show any significant differences in TL as compared to nonselected sperm (p > .05). Negative correlations between TL and sperm motility (r = -.308; p = .049) and concentration (r = -.353; p = .028) were found. Furthermore, exposure of sperm 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 TL in sperm. Preliminary clinical results from patients included in this study indicate that TL was shorter in spermatozoa from couples who never achieved a pregnancy compared to couples who did achieve at least one natural pregnancy (p < .05); however, the clinical utility of this biomarker still needs to be confirmed in further studies.

Associations of sperm telomere length with semen parameters, clinical outcomes and lifestyle factors in human normozoospermic samples

“…21 In another study, it was demonstrated that spermatozoon with shorter STL was associated with lower natural pregnancy rates compared with couples who did achieve pregnancy naturally with longer STL. 18 Herein, a trend was observed in which 14,16,18,21 Studies investigating the association between STL and sperm quality have shown a positive correlation with total sperm count and STL. 14,21 In other studies using normozoospermic samples, STL was found to be positively linked to sperm progressive motility/ vitality and negatively linked to sperm DNA fragmentation 15, but no association was detected with male age, sexual abstinence, total sperm count, concentration and morphology.…”

“…16,17 Furthermore, Lafuente et al demonstrated that STL in infertile men was negatively correlated with sperm concentration and progressive motility. 18 An increasing number of studies have found that STL may play a role in reproduction as a molecular marker of sperm quality.…”

The association of female and male infertility with telomere length (Review)

“…In total, 15 of the positively associated studies detected a sperm TL (STL) association (68-70,72,74-84), while 3 studies detected an LTL association (73,85,86), and one study detected both STL and LTL (71). In several studies, shorter STL was reported in association to infertility (72,76,78,80) while Vecoli et al reported an increase in STL in areas of high environmental exposure (77). Although Turner and Hartshorne found an association between female fertility and STL, they did not find a significant association for male fertility (39).…”

Reactive oxygen species impact on sperm DNA and its role in male infertility

“…Although telomere length is partially determined genetically and by paternal age, it is also influenced by internal and external environmental factors such as obesity, infection, oxidative stress, smoking, psychological and lifestyle stress, environmental factors and diet (Thilagavathi et al., ). However, currently, analysing sperm telomere length is not a part of standard clinical practice due to some conflicting data surrounding its relationship with sperm DNA fragmentation, sperm parameters and reproductive outcomes (Cariati et al., ; Lafuente et al., ; Rocca et al., ; Turner & Hartshorne, ; WHO, ). Thus, the validity of telomere length as a diagnostic tool of infertility and OS has yet to be confirmed.…”