Abstract
The presence of DNA fragmentation in semen is associated with poor results in ART (Assisted Re-productive Technology). This has led to the introduction of sperm DNA integrity testing in the clinical assessment of male infertility. The TUNEL assay is one of the most commonly used tests to measure DNA fragmentation in research studies, but it is now being optimized for routine clinical use. So, the objectives of our study were to install the TUNEL assay in our laboratory and to use it to assess the degree of DNA fragmentation in our patients dealing with couple infertility. Forty seven (47) and 25 samples from patients followed up for infertility and known fertile men were analyzed between August 2013 and July 2015 respectively. The sperm samples were evaluated according to the World Health Organization Guidelines. Sperm DNA damage was assessed by the TUNEL assay, with a standardized protocol that we adapted for reading using fluorescence microscopy instead of flow cytometry. The Sperm DNA Fragmentation Index was significantly higher in patients with infertility compared to the controls (22.2% ± 5.6% vs. 16.7% ± 0.7%) with a p < 0.05. This Index was also high in patients with varicocele compared to the control group (22.8% ± 9.2 vs. 16.7% ± 0.7%) (p < 0.01). After establishing the ROC curve (Receiver Operating Characteristics curve), we found a 15% threshold of DNA fragmentation, separating the patients with infertility from the control group. In our study, a 15% threshold positivity of DNA fragmentation using the TUNEL assay was highly associated with infertility. The results indicate that high level DNA fragmentation is associated with infertility.
Highlights
DNA damage in spermatozoa is considered as an important cause of male infertility [1]
The TUNEL assay measures both single and double strand DNA fragmentation, at specific points. It is a direct quantification of sperm DNA breaks and the results can be compared with other studies using the same assay
In the group of patients with infertility we found no correlation between semen parameters and DNA fragmentation index (Table 2)
Summary
DNA damage in spermatozoa is considered as an important cause of male infertility [1]. High DNA fragmentation levels have a negative influence on cleavage rates, embryo quality and pregnancy outcomes in IVF (In Vitro Fertilization) as well as in ICSI (Intracytoplasmic Sperm Injection) [5]. To overcome this abnormality, the oocyte is well known for its capacity to repair DNA damage in the spermatozoa [6]. The TUNEL assay is still being optimized, for example, Sharma et al [8] and Sergerie et al [9] have proposed a methodology to standardize TUNEL test for routine clinical use They have established their threshold values at 19.25% and 20% respectively and these can be used to install the TUNEL assay. With the TUNEL assay, the reading of the results can be performed with a fluorescence microscope [10] [11], but the reported thresholds are lower [11] [12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
