In infertile couples, approximately 20% of infertility cases are attributed solely to male factors. Recently, the evaluation of sperm quality has gained increasing importance in the treatment of male infertility. Sperm quality is assessed through semen volume, sperm concentration, sperm motility, and the sperm deoxyribonucleic acid (DNA) fragmentation index. Various factors, including varicocele, environmental influences, and genomic abnormalities, can affect semen quality and increase sperm DNA fragmentation (SDF). In this virtual issue of Reproductive Medicine and Biology (RMB), the editor presents recent articles focusing on semen and sperm quality in male infertility treatment.

Shiraishi reviewed the role of varicocele repair in the context of assisted reproductive technologies (ARTs). Drawing on their experience with over 2000 cases, they described the impact of varicocele repair on semen quality, noting its efficacy not only for non-ART pregnancies but also its potential to improve ART outcomes (DOI: 10.1002/rmb2.12589). In clinical practice, Yoshiakwa–Terada et al. investigated the relationship between sperm parameters assessed via computer-assisted sperm analysis and SDF levels. Their study indicated that sperm motility and head morphology were indicators of SDF, suggesting that detailed sperm analysis might enhance ART success rates (DOI: 10.1002/rmb2.12585). Tanaka et al. clustered seminal plasma/serum ratios of multiple trace elements in cases of male subfertility, finding that clusters with early fraction characteristics exhibited significantly lower semen volume and higher pregnancy rates, whether from spontaneous pregnancy or intrauterine insemination. Their findings imply that unknown post-testicular factors might contribute to unexplained declines in semen quality (DOI: 10.1002/rmb2.12584). Tomita et al. explored the relationship between semen oxidative reduction potential (ORP) measured at initial semen examination and in vitro fertilization outcomes. They found that the rate of transferable embryos was significantly higher in patients with elevated semen ORP. However, these patients exhibited a trend towards lower clinical pregnancy rates but with a reduced abortion rate compared to the low ORP group, raising questions about the utility of ORP measurement in semen assessment (DOI: 10.1002/rmb2.12501).

From an environmental perspective, Mokhtarah et al. studied the effects of Wi-Fi exposure on male reproductive health. Their study on rats demonstrated that Wi-Fi exposure led to decreased sperm quality while administering edible bird’s nest protected against Wi-Fi-induced damage (DOI: 10.1002/rmb2.12606). In terms of genomic aberrations and sperm quality, RMB published three articles on this topic in 2024, including two original papers and a case report. Kuribayashi et al. examined the role of the Kelch-like ECH-associated protein 1 (KEAP1)-nuclear factor erythroid 2-related factor 2 oxidative stress response system in age-related changes in spermatogenesis. Their study in mice revealed that inhibiting KEAP1 in aged mice significantly increased sperm counts compared to controls (DOI: 10.1002/rmb2.12595). Zhang et al. investigated the impact of azoospermia factor c (AZFc) microdeletions on intracytoplasmic sperm injection outcomes in clinical practice. Their findings indicated that patients with AZFc microdeletions had lower rates of normal fertilization and high-quality embryos than the control group, although clinical pregnancy, miscarriage, and live birth rates did not differ significantly (DOI: 10.1002/rmb2.12596). Muranishi et al. presented a case report on a patient with isolated non-obstructed azoospermia and potassium channel tetramerization domain containing 19 variants. Semen analyses confirmed azoospermia and microdissection testicular sperm extraction (MD-TESE) confirmed the lack of spermatozoa. Although the patients underwent a 6-month course of adjuvant hormone therapy with recombinant follicle-stimulating hormone, there was no improvement in testicular histology at the second MD-TESE (DOI: 10.1002/rmb2.12608).

Thus, semen and sperm quality in the treatment of male infertility has been examined from multiple perspectives. Continual updates in this area are essential to develop and refine treatment strategies tailored to individual couples.

Editor
Hisanori Taniguchi