Sperm chromatin integrity: etiologies and mechanisms of abnormality, assays, clinical importance, preventing and repairing damage

The standard semen analysis is the first line and the most popular laboratory test in the diagnosis of male fertility. It evaluates sperm concentration, motility, morphology and their vitality. However, it is well-known that normal results of semen analysis can not exclude men from the causes of couples' infertility. One of the most important parameters of sperm in its fertilizing potential is [Sperm chromatin integrity] that has direct positive correlation with Assisted Reproductive Techniques [ART] outcomes including; fertilization rate, embryo quality, pregnancy and successful delivery rate. It seems that sperm DMA chromatin integrity provides better diagnostic and prognostic approaches than standard semen parameters. For these reasons understanding the sperm chromatin structure, etiology of sperm chromatin abnormality, identification factors that disturbs sperm chromatin integrity and the mechanism of their action can help in recognizing the causes of couples' infertility. Various methods of its evaluation, its importance in male fertility, clinical relevance in the outcomes of ART and application of laboratory and medical protocols to improve this integrity have valuable position in diagnosis and treatment of male infertility. There has recently been interest in the subject and its application in the field of andrology. Therefore, with regard to the above mentioned importance of sperm chromatin integrity, this review article describes details of the useful information pertaining to sperm DMA damage including the origins, assessments, etiologies, clinical aspects, and prevention of it

Effects of sperm chromatin integrity on fertilization rate and embryo quality following intracytoplasmic sperm injection

Sperm chromatin integrity has been being recognized as an important factor in male fertility. During normal fertilization, high quality sperm with intact chromatin are selected through natural selection in journey from vagina to fallopian tube. However, using Assisted Reproductive Techniques, particularly ICSI, the natural selection is bypassed. Therefore sperm with DMA breakage have the opportunity to fertilize the egg which may lead to decreased embryo quality and implantation rate. The aim of this study was to evaluate the effects of sperm chromatin integrity on ICSI outcomes. A total of 200 semen samples were collected from couples undergoing ICSI and were analyzed according to WHO criteria. Each sample was evaluated for sperm chromatin integrity using four cytochemical assays and semen processing by swim up method. The ICSI was carried out according to a long-term pituitary down-regulation protocol. The correlation between sperm parameters, sperm chromatin integrity and ICSI outcomes [fertilization rate and embryo quality] was examined. The mean number of oocyte, fertilization rate and cleavage embryos per cycles was 7.5 +/- 5.0, 74.O6% +/- 25 and 5.4 +/- 3.6, respectively. There was not significant correlation between the results of chromatin assays [AO, AB, TB, and CMA3] and fertilization outcomes following ICSI. The fertilization rate was significantly higher for a group with less than 10% chromatin abnormality [p<0.05]. Sperm chromatin integrity is essential for successful fertilization, embryo development and normal pregnancy. A protamine deficiency appeared to affect fertilization rate and embryo quality. However, the presence of confounding factors such as selection of spermatozoa according to normal morphology may influence the effect of sperm chromatin status on ICSI outcomes