Title: Is sperm DNA fragmentation a hidden male factor in human infertility?
Abstract: OBJECTIVE: Semen analysis, including strict morphology, remains the standard evaluation for the male partner in infertile couples. Sperm DNA integrity could influence fertilization rates and embryo development in IVF, even in men with normal semen parameters. The objective of our study was to determine the presence of sperm DNA fragmentation assessed by Tunel and the apoptotic marker cleaved caspase-3, in infertile patients with normal semen analysis. DESIGN: Retrospective data analysis. MATERIALS AND METHODS: A total of 600 infertile patients were studied during 18 months; 564 patients (group I) had at least one abnormal sperm parameter (count, motility, morphology or combination), the remaining 36 patients (group II) had normal semen analysis.Sperm DNA damage was assessed by the TUNEL assay using epifluorescence (normal <20%) and cleaved caspase-3 concentration visualized by immunocytochemistry (Kotwicka 2008, normal <11%) in both groups and compared. Results are expressed as mean ± SD. Statistical analysis was done by student's t-test and Pearson chi-square, a p<0.05 was considered significant. RESULTS: The mean TUNEL value in group I was 19.98±10.7% which was not statistically different than 18.6±11.0 % in group II (p=.480).The mean caspase-3 value was 8.6±6.4 % similar to the values of 9.1±7.4% in group II (p=.672). The percentage of patients with abnormal levels of DNA fragmentation were similar in both groups, group I, 52.1%, group II 52.8% (p=.940). High levels of caspase-3 were also similar, group I 31.7%, group II 27.8% (p=.682). CONCLUSION: Our results showed that infertile men with normal semen analysis and history of poor fertilization or poor embryo quality in vitro, should be tested for sperm DNA fragmentation, since abnormal levels are as common as in patients with poor semen quality. Abnormal sperm DNA integrity can be detrimental to pregnancy outcome and future efforts should be directed toward reducing the percentage of apoptotic sperm in semen samples prior to performing ICSI (Rawe,2010).