Sperm DNA Fragmentation: Unraveling Its Imperative Impact on Male Infertility Based on Recent Evidence.

Male factors may be present in up to 50-70% of infertile couples and the prevalence of male infertility accounts for 20-30% of infertility cases. Understanding the mechanisms and causes behind male infertility remains a challenge, but new diagnostic tools such as DNA fragmentation might aid in cases where the routine semen analysis is insufficient. DNA fragmentation, which refers to damages or breaks of the genetic material of the spermatozoa, is considered one of the main causes of male infertility due to impaired functional capability of sperm. The aim of the present narrative review is to investigate and enlighten the potential correlation between DNA fragmentation and male infertility parameters such as the seminal profile and the reproductive outcomes. Comprehensive research in PubMed/Medline and Scopus databases was conducted and 28 studies were included in the present review. Fourteen studies provided data regarding the impact of DNA fragmentation and seminal parameters and showed a correlation of significantly lower sperm count, lower concentration, motility, and abnormal morphology with an increased DNA fragmentation index (DFI). Similarly, 15 studies provided data regarding the impact of DFI on reproductive outcomes. Two studies showed higher aneuploidy rates with higher DFI values, and seven studies showed significantly lower pregnancy rates and live birth rates with higher DFI values. Ultimately, the studies included in this review highlight, collectively, the importance of measuring sperm DFI in the assessment of male infertility. Further studies are needed to explore the effectiveness of interventions aiming to reduce DFI levels.

Oocyte Maturation and miRNAs: Studying a Complicate Interaction to Reveal Possible Biomarkers for Female Infertility.

Cellular metabolism, apoptosis, fertilization, and proliferation of granulosa cells belong to a battery of processes where microRNAs can be detected and associated with infertility. The aim of the present review is to focus on mammalian oocyte maturation events and the association between oocyte growth and miRNA expression. PubMed/Medline, Google Scholar and Scopus databases were searched, and 33 studies were included. Regarding the correlation among miRNA expression and the regulation of granulosa cells and cumulus cells, the most important miRNAs were let-7b, let-7c and miR-21. Additionally, the loss of Dicer, an enzyme involved in miRNA biogenesis, is probably a crucial factor in oogenesis, oocyte maturation and embryogenesis. Furthermore, miRNAs interfere with different cellular mechanisms like apoptosis, steroidogenesis, genome integrity, angiogenesis, antioxidative response and, consequently, oocyte maturation. Hence, it is of major importance to clarify the role and mechanism of each miRNA as understanding its action may develop new tools and establish new diagnostic and treatment approaches for infertility and ovarian disorders.