Sperm DNA Fragmentation: Causes, Effects and Relevance in IVF Outcomes

Abstract

Sperm DNA fragmentation, characterized by damaged or broken DNA strands within sperm cells, has been recognized as an important factor in male infertility and poor ART outcome. This lecture aims to provide an overview of the causes, effects, and relevance of sperm DNA fragmentation in in vitro fertilization (IVF) outcomes and look into the latest evidences from the literatures. Causes: Sperm DNA fragmentation can result from various factors, including oxidative stress, advanced paternal age, lifestyle factors such as smoking and excessive alcohol consumption, environmental exposures, genotoxic agents, and underlying genetic abnormalities. These factors can induce DNA damage during sperm development, during the transit of sperm through the male reproductive tract or during the storage of the sperm in epididymis. Relevance in IVF Outcomes: The assessment of sperm DNA fragmentation has emerged as a valuable tool in evaluating male infertility and predicting IVF success. Several methods, including the sperm chromatin structure assay (SCSA), terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL), comet assay, and other commercial detection kits, are available to measure sperm DNA fragmentation. Previous small cohort studies have demonstrated that higher levels of sperm DNA fragmentation are associated with lower pregnancy rates, decreased embryo quality, and an increased risk of pregnancy loss in IVF cycles. Therefore, incorporating sperm DNA fragmentation analysis into the routine assessment of male infertility can aid in optimizing treatment strategies and improving IVF outcomes. Recent evidences: Latest large clinical studies showed a limited association to IVF outcome. The DFI remains controversial as a predictive tool. Nonetheless, sperm DNA fragmentation is still believed to be a significant factor affecting male fertility and IVF outcomes. Further research is warranted to explore the mechanisms underlying DNA fragmentation, develop standardized assessment methods, and explore potential interventions to mitigate the adverse effects of sperm DNA damage on IVF success.