Spermatozoal sensitive biomarkers to defective protaminosis and fragmented DNA

Abstract

Human sperm DNA damage may have adverse effects on reproductive outcome. Infertile men possess substantially more spermatozoa with damaged DNA compared to fertile donors. Although the extent of this abnormality is closely related to sperm function, the underlying etiology of ensuing male infertility is still largely controversial. Both intra-testicular and post-testicular events have been postulated and different mechanisms have been proposed to explain the presence of damaged DNA in human spermatozoa. Three among them, i.e. abnormal chromatin packaging, oxidative stress and apoptosis, are the most studied and discussed in the present review. Furthermore, results from numerous investigations are presented, including our own findings on these pathological conditions, as well as the techniques applied for their evaluation. The crucial points of each methodology on the successful detection of DNA damage and their validity on the appraisal of infertile patients are also discussed. Along with the conventional parameters examined in the standard semen analysis, evaluation of damaged sperm DNA seems to complement the investigation of factors affecting male fertility and may prove an efficient diagnostic tool in the prediction of pregnancy outcome.

Sperm DNA Fragmentation Assays Correlate with Sperm Abnormal Morphology and the Pregnancy Outcome

“…In absence of recognized standard values, some reports established that a normal semen sample generally contains less than 25% stained spermatozoa [37,38] and more recent clinical observations identified threshold values from 28 to over 30%, since no pregnancies were reported following in vitro fertilization and ICSI with semen samples exceeding this percentage [3,24,39,40] In this study we did not find any correlation between SDI and DFI. This lack of correlation has been also shown by other authors [41,42] suggesting that the two kinds of DNA damage are generated by different etiological pathways leading to abnormal chromatin packaging during sperm maturation process for SDI and to an increased sensitivity to oxidative stress and/or apoptosis for DFI [2,43].…”

Flow cytometry for the assessment of animal sperm integrity and functionality: state of the art

“…Apoptosis markers have been detected in spermatozoa of many species, but the role of these markers is probably not yet elucidated completely. 49,[119][120][121][122] Changes of sperm membrane permeability have been considered as a typical event of apoptosis in many studies. Since cryopreservation, freezing and thawing cause cryodamage, and presumably even apoptotic-like changes, 123 apoptotic markers can be good tools for forecasting semen freezability and cellular damage occur during cryopreservation, albeit not necessarily indicting apoptosis really occurs.…”

The clinical significance of sperm DNA damage detection combined with routine semen testing in assisted reproduction

“…However, in cases with normal semen but a relatively higher DFI value, the outlook is not promising. As a result, the detection of damaged DNA in spermatozoa needs to be conducted along with standard semen analysis (12).…”

“…have undergone arcsine transformation and square root changing. (12)(13)(14)(15), ii) the single-cell gel electrophoresis (comet) assay (16)(17)(18), and iii) the in situ nick translation assay with or without sperm decondensation (19,20). Indirect methods include: i) the acridine orange technique (AOT), first introduced by Teyada et al (10), and ii) sperm chromatin structure assay (SCSA) (21).…”