Characterization of DNA cleavage produced by seminal plasma using leukocytes as a cell target

ABSTRACT

Numerous studies have shown the presence of DNA lesions in human spermatozoa affecting sperm quality. However, the nature of this anomaly and its relationship with patient etiology are poorly understood since different mechanisms can be involved in the formation of these novel DNA configurations including the action of a seminal plasma nuclease activity. The objective of this study was to assess the capacity of seminal plasma for producing endogenous DNA cleavage using nuclei of peripheral blood leukocytes as external targets. For this purpose, we used seminal plasma from fertile males with normal semen parameters to produce DNA cleavage in a sample of leukocytes. Three different tests were performed to visualize DNA cleavage: (a) DNase activity detection, (b) DNA Breakage Detection-Fluorescence In Situ Hybridization (DBD-FISH), and (c) Two-dimensional comet assay (Two-tail comet assay). Our results demonstrate that: (i) the seminal plasma is able to cleave DNA compacted with histones in the leukocytes; (ii) this DNA cleavage can be associated with DNase activity and (iii) DNA damage mainly corresponds to single-strand DNA breaks. In conclusion, capacity of seminal plasma for producing DNA cleavage represents a solid contribution to expand the analysis of the standard seminal profile and could constitute a putative diagnostic tool for evaluating male infertility.

Abbreviations: ALS: alkali labile sites; ART: Assisted Reproduction Technologies; DBD-FISH: DNA Breakage Detection-Fluorescence In Situ Hybridization; DNA: deoxyribonucleic acid; DSBs-DNA: double-strand DNA; FITC: Fluorescein IsoThioCyanate; GEDA: Gravity Enforced Diffusion Assays; PBS: phosphate-buffered saline; ROS: Reactive Oxigen Species; SSBs-DNA: single-strand DNA; SSC: saline-sodium citrate.

KEYWORDS:

• Human reproduction
• sperm DNA damage
• DNase activity
• male factor
• DBD-FISH
• comet assay

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

Data collection, manuscript preparation: CGV, JBN; Manuscript revision: EICG, CGV, JBN, JG; Study design, data collection, study supervision, manuscript preparation: JG, EICG.

Ethical considerations

The Institutional Review Board of Instituto Mexicano del Seguro Social, IMSS, México approved this study, and written consent was obtained from all participants.

Additional information

Funding

The Spanish Ministry of Economy and Competitiveness provided financial support. MINECO [BFU-2013-44290-R].