Male infertility

A systematic review of interventions to improve male knowledge of fertility and fertility-related risk factors

Male infertility is a global health concern. The effectiveness of interventions developed to improve males' knowledge of fertility regulation and fertility-related risk factors remains unclear. This systematic review aimed to synthesize and evaluate the evidence for these interventions. Four databases were searched from inception to June 2023. Eligible studies examined interventions to increase fertility knowledge among presumed fertile males aged ≥16 years of age. Conference abstracts, protocols and studies without sex-disaggregated results for males were excluded. A narrative synthesis without meta-analysis was performed. A total of 4884 records were identified. Five studies (reported in six publications), all conducted in high-income countries, were included. Two were randomized control trials, and three were experimental studies. Interventions were delivered in person by a health professional (n = 3), online and via a mobile app. All studies showed a significant improvement in knowledge of fertility or fertility-related risk factors from baseline to follow-up. The largest improvement was observed for secondary and vocational students. A moderate, long-term retainment of knowledge was observed at two-year follow-up in one study. Available evidence suggests interventions to improve males' fertility knowledge are effective, particularly for younger, less educated males.

High Concentration of Iron Ions Contributes to Ferroptosis-Mediated Testis Injury

In order to explore the effect of excessive iron supplementation on ferroptosis in mouse testes, Kunming mice received injections of varying concentrations of iron. The organ weight, sperm density, and malformation rate were measured. Observations of pathological and ultrastructural alterations in spermatogenic tubules were conducted using haematoxylin eosin (HE) staining and transmission electron microscopy(TEM). Transcript levels of related genes and serum biochemical indicators were measured in mouse testicular tissue. The results showed that higher iron concentration inhibited the growth of mice; reduced the organ coefficients of the testis, heart, and liver; and increased the rate of sperm malformation and mortality. Supplementation with high levels of iron ions can adversely affect the male reproductive system by reducing sperm count, damaging the structure of the seminiferous tubules and causing sperm cell abnormalities. In addition, the iron levels also affected the immune response and blood coagulation ability by affecting the red blood cells, white blood cells and platelets. The results showed that iron ions can affect mouse testicular tissue and induce ferroptosis by altering the expression of ferroptosis-related genes. However, the degree of effect was different for the different concentrations of iron ions. The study also revealed the potential role of deferoxamine in inhibiting the occurrence of ferroptosis. Nevertheless, the damage caused to the testis by deferoxamine supplementation suggests the need for further research in this direction. This study provides reference for reproductive toxicity induced by environmental iron exposure and clarifies the mechanism of reproductive toxicity caused by iron overload and the important role of iron in the male reproductive system.

USP11 regulates proliferation and apoptosis of human spermatogonial stem cells via HOXC5-mediated canonical WNT/β-catenin signaling pathway

Spermatogonial stem cells (SSCs) are capable of transmitting genetic information to the next generations and they are the initial cells for spermatogenesis. Nevertheless, it remains largely unknown about key genes and signaling pathways that regulate fate determinations of human SSCs and male infertility. In this study, we explored the expression, function, and mechanism of USP11 in controlling the proliferation and apoptosis of human SSCs as well as the association between its abnormality and azoospermia. We found that USP11 was predominantly expressed in human SSCs as shown by database analysis and immunohistochemistry. USP11 silencing led to decreases in proliferation and DNA synthesis and an enhancement in apoptosis of human SSCs. RNA-sequencing identified HOXC5 as a target of USP11 in human SSCs. Double immunofluorescence, Co-immunoprecipitation (Co-IP), and molecular docking demonstrated an interaction between USP11 and HOXC5 in human SSCs. HOXC5 knockdown suppressed the growth of human SSCs and increased apoptosis via the classical WNT/β-catenin pathway. In contrast, HOXC5 overexpression reversed the effect of proliferation and apoptosis induced by USP11 silencing. Significantly, lower levels of USP11 expression were observed in the testicular tissues of patients with spermatogenic disorders. Collectively, these results implicate that USP11 regulates the fate decisions of human SSCs through the HOXC5/WNT/β-catenin pathway. This study thus provides novel insights into understanding molecular mechanisms underlying human spermatogenesis and the etiology of azoospermia and it offers new targets for gene therapy of male infertility.

The Evolutionary Route of in vitro Human Spermatogenesis: What is the Next Destination?

Malfunction in spermatogenesis due to genetic diseases, trauma, congenital disorders or gonadotoxic treatments results in infertility in approximately 7% of males. The behavior of spermatogonial stem cells (SSCs) within three-dimensional, multifactorial, and dynamic microenvironment implicates a niche that serves as a repository for fertility, since can serve as a source of mature and functional male germ cells. Current protocols enable reprogramming of mature somatic cells into induced pluripotent stem cells (iPSCs) and their limited differentiation to SSCs within the range of 0-5%. However, the resulting human iPSC-derived haploid spermatogenic germ cell yield in terms of number and functionality is currently insufficient for transfer to infertility clinic as a therapeutic tool. In this article, we reviewed the evolution of experimental culture platforms and introduced a novel iPSCs-based approach for in vitro spermatogenesis based on a niche perspective bearing cellular, chemical, and physical factors that provide the complex arrangement of testicular seminiferous tubules embedded within a vascularized stroma. We believe that bioengineered organoids supported by smart bio-printed tubules and microfluidic organ-on-a-chip systems offer efficient, precise, personalized platforms for autologous pluripotent stem cell sources to undergo the spermatogenetic cycle, presenting a promising tool for infertile male patients with complete testicular aplasia.

Achilles' heel of male infertility: good LEGO players

In a recent journal article, Chen et al. identified a germ cell-specific cofactor, STYXL1, associated with male fertility function. Deletion of STYXL1 prevents the LEGO player CCT complex from properly folding key microtubule proteins of the sperm flagellum, which affects sperm motility and male fertility function.

Exploring the biological roles of DHX36, a DNA/RNA G-quadruplex helicase, highlights functions in male infertility: A comprehensive review

It is estimated that 15 % of couples at reproductive age worldwide suffer from infertility, approximately 50 % of cases are caused by male factors. Significant progress has been made in the diagnosis and treatment of male infertility through assisted reproductive technology and molecular genetics methods. However, there is still inadequate research on the underlying mechanisms of gene regulation in the process of spermatogenesis. Guanine-quadruplexes (G4s) are a class of non-canonical secondary structures of nucleic acid commonly found in genomes and RNAs that play important roles in various biological processes. Interestingly, the DEAH-box helicase 36 (DHX36) displays high specificity for the G4s which can unwind both DNA G4s and RNA G4s enzymatically and is highly expressed in testis, thereby regulating multiple cellular functions including transcription, pre-mRNA splicing, translation, telomere maintenance, genomic stability, and RNA metabolism in development and male infertility. This review provides an overview of the roles of G4s and DHX36 in reproduction and development. We mainly focus on the potential role of DHX36 in male infertility. We also discuss possible future research directions regarding the mechanism of spermatogenesis mediated by DHX36 through G4s in spermatogenesis-related genes and provide new targets for gene therapy of male infertility.

The Effect of Carob (Ceratonia Siliqua) on Sperm Parameters of Infertile Men: Systematic Review and Meta-Analysis of Randomized Controlled Trials

Carob (Ceratonia siliqua) supplements can increase sperm quality. This study aimed to summarize the available evidence about the effects of carob (Ceratonia siliqua) supplements on sperm quality and reproductive hormones in infertile men. Systematic searches of five databases were conducted from inception to October 20, with the last update on November 20, 2023. Randomized clinical trials (RCTs) that compared carob (Ceratonia siliqua) supplements with nonintervention control groups on infertile man. Risk of bias and certainty of evidence were assessed by the Cochrane risk of bias tool 2. Summary effect size measures were calculated using a random-effects model estimation and are reported as standardized mean differences and 95% confidence intervals. Reporting followed the PRISMA guidelines. The analysis included four studies involving 236 infertile men. It was found that sperm motility of infertile men improved after carob intervention (MD:11.30, 95% CI:5.97 to 16.64, Z = 4.15, p < 0.00001), and there was a significant difference compared to control groups. The effect size of carob on semen quantity in infertile men was positive, and the relationship was statistically significant (MD:5.42, 95% CI:1.58 to 9.42, Z = 2.77, p = 0.006). When hormone parameters of infertile men were analyzed, the MDA (malondialdehyde) value decreased compared to the control group (MD = -4.81, 95% CI: -10.18 to 0.56, Z = 1.76, p = 0.08), and there was a significant difference between them. Carob (Ceratonia siliqua) supplements was associated with improvement in sperm quality compared with nonintervention control groups in infertile man. However, high-quality, larger RCTs are required to draw more definitive conclusions.

Elucidating the Role of OXPHOS Variants in Asthenozoospermia: Insights from Whole Genome Sequencing and an In Silico Analysis

Infertility is a global health challenge that affects an estimated 72.4 million people worldwide. Between 30 and 50% of these cases involve male factors, showcasing the complex nature of male infertility, which can be attributed to both environmental and genetic determinants. Asthenozoospermia, a condition characterized by reduced sperm motility, stands out as a significant contributor to male infertility. This study explores the involvement of the mitochondrial oxidative phosphorylation (OXPHOS) system, crucial for ATP production and sperm motility, in asthenozoospermia. Through whole-genome sequencing and in silico analysis, our aim was to identify and characterize OXPHOS gene variants specific to individuals with asthenozoospermia. Our analysis identified 680,099 unique variants, with 309 located within OXPHOS genes. Nine of these variants were prioritized due to their significant implications, such as potential associations with diseases, effects on gene expression, protein function, etc. Interestingly, none of these variants had been previously associated with male infertility, opening up new avenues for research. Thus, through our comprehensive approach, we provide valuable insights into the genetic factors that influence sperm motility, laying the foundation for future research in the field of male infertility.

Safety evaluation of single-sperm cryopreservation technique applied in intracytoplasmic sperm injection

Intracytoplasmic sperm injection (ICSI) is a technique that directly injects a single sperm into the cytoplasm of mature oocytes. Here, we explored the safety of single-sperm cryopreservation applied in ICSI. This retrospective study enrolled 186 couples undergoing ICSI-assisted pregnancy. Subjects were allocated to the fresh sperm (group A)/single-sperm cryopreservation (group B) groups based on sperm type, with their clinical baseline/pathological data documented. We used ICSI-compliant sperm for subsequent in vitro fertilization and followed up on all subjects. The recovery rate/cryosurvival rate/sperm motility of both groups, the pregnancy/outcome of women receiving embryo transfer, and the delivery mode/neonatal-related information of women with successful deliveries were recorded. The clinical pregnancy rate, cumulative clinical pregnancy rate, abortion rate, ectopic pregnancy rate, premature delivery rate, live birth delivery rate, neonatal birth defect rate, and average birth weight were analyzed. The two groups showed no significant differences in age, body mass index, ovulation induction regimen, sex hormone [anti-Müllerian hormone (AMH)/follicle-stimulating hormone (FSH)/luteinizing hormone (LH)] levels, or oocyte retrieval cycles. The sperm recovery rate (51.72%-100.00%) and resuscitation rate (62.09% ± 16.67%) in group B were higher; the sperm motility in the two groups demonstrated no significant difference and met the ICSI requirements. Group B exhibited an increased fertilization rate, decreased abortion rate, and increased safety versus group A. Compared with fresh sperm, the application of single-sperm cryopreservation in ICSI sensibly improved the fertilization rate and reduced the abortion rate, showing higher safety.

Genome-wide analyses identify 21 infertility loci and over 400 reproductive hormone loci across the allele frequency spectrum

Genome-wide association studies (GWASs) may help inform treatments for infertility, whose causes remain unknown in many cases. Here we present GWAS meta-analyses across six cohorts for male and female infertility in up to 41,200 cases and 687,005 controls. We identified 21 genetic risk loci for infertility (P≤5E-08), of which 12 have not been reported for any reproductive condition. We found positive genetic correlations between endometriosis and all-cause female infertility (rg=0.585, P=8.98E-14), and between polycystic ovary syndrome and anovulatory infertility (rg=0.403, P=2.16E-03). The evolutionary persistence of female infertility-risk alleles in EBAG9 may be explained by recent directional selection. We additionally identified up to 269 genetic loci associated with follicle-stimulating hormone (FSH), luteinising hormone, oestradiol, and testosterone through sex-specific GWAS meta-analyses (N=6,095-246,862). While hormone-associated variants near FSHB and ARL14EP colocalised with signals for anovulatory infertility, we found no rg between female infertility and reproductive hormones (P>0.05). Exome sequencing analyses in the UK Biobank (N=197,340) revealed that women carrying testosterone-lowering rare variants in GPC2 were at higher risk of infertility (OR=2.63, P=1.25E-03). Taken together, our results suggest that while individual genes associated with hormone regulation may be relevant for fertility, there is limited genetic evidence for correlation between reproductive hormones and infertility at the population level. We provide the first comprehensive view of the genetic architecture of infertility across multiple diagnostic criteria in men and women, and characterise its relationship to other health conditions.

Deleterious variant in FAM71D cause male infertility with asthenoteratospermia

Asthenoteratospermia is a significant cause of male infertility. FAM71D (Family with sequence similarity 71, member D), as a novel protein exclusively expressed in the testis, has been found to be associated with sperm motility. However, the association of FAM71D mutation with male infertility has yet to be examined. Here, we conducted whole-exome sequencing and identified a homozygous missense mutation c.440G > A (p. Arg147Gln) of FAM71D in an asthenoteratospermia-affected man from a consanguineous family. The FAM71D variant is extremely rare in human population genome databases and predicted to be deleterious by multiple bioinformatics tools. Semen analysis indicated decreased sperm motility and obvious morphological abnormalities in sperm cells from the FAM71D-deficient man. Immunofluorescence assays revealed that the identified FAM71D mutation had an important influence on the assembly of sperm structure-related proteins. Furthermore, intra-cytoplasmic sperm injection (ICSI) treatment performed on the infertile man with FAM71D variant achieved a satisfactory outcome. Overall, our study identified FAM71D as a novel causative gene for male infertility with asthenoteratospermia, for which ICSI treatment may be suggested to acquire good prognosis. All these findings will provide effective guidance for genetic counselling and assisted reproduction treatments of asthenoteratospermia-affected subjects.

Discovery of a novel miRNA involved in the regulation of male infertility in zebrafish

Azoospermia and asthenospermia are common manifestations of male infertility, but it needs further studies to understand the intrinsic regulation mechanism. As a popular model organism, zebrafish is often used to assess reproductive complications. In this study, by analyzing miRNA transcriptome of the mature triploid zebrafish testis afflicted with spermatogenic dysfunctions, leading to the identification of 36 miRNAs that are differentially expressed in comparison with diploid, which are predicted to target 2737 genes. Subsequent functional annotation of these genes pinpointed two miRNAs might association with spermatogenesis. Inhibitory experiments showed that NC_007115.7.7_998413 inhibited conducts a substantial decline in sperm density, and conducted lower embryo fertilization rate than control. And putative target genes qRT-PCR evaluation showed that spata2 was significant down-regulate upon inhibited NC_007115.7.7_998413. In summary, this research positions newly identified miRNA NC_007115.7.998413 as a regulatory factor in male zebrafish reproductive development, enhancing our comprehension of the molecular regulated pathways involved in spermatogenesis.

Declining global fertility rates and the implications for family planning and family building: an IFFS consensus document based on a narrative review of the literature

BACKGROUND

Family-planning policies have focused on contraceptive approaches to avoid unintended pregnancies, postpone, or terminate pregnancies and mitigate population growth. These policies have contributed to significantly slowing world population growth. Presently, half the countries worldwide exhibit a fertility rate below replacement level. Not including the effects of migration, many countries are predicted to have a population decline of >50% from 2017 to 2100, causing demographic changes with profound societal implications. Policies that optimize chances to have a child when desired increase fertility rates and are gaining interest as a family-building method. Increasingly, countries have implemented child-friendly policies (mainly financial incentives in addition to public funding of fertility treatment in a limited number of countries) to mitigate decreasing national populations. However, the extent of public spending on child benefits varies greatly from country to country. To our knowledge, this International Federation of Fertility Societies (IFFS) consensus document represents the first attempt to describe major disparities in access to fertility care in the context of the global trend of decreasing growth in the world population, based on a narrative review of the existing literature.

OBJECTIVE AND RATIONALE

The concept of family building, the process by which individuals or couples create or expand their families, has been largely ignored in family-planning paradigms. Family building encompasses various methods and options for individuals or couples who wish to have children. It can involve biological means, such as natural conception, as well as ART, surrogacy, adoption, and foster care. Family-building acknowledges the diverse ways in which individuals or couples can create their desired family and reflects the understanding that there is no one-size-fits-all approach to building a family. Developing education programs for young adults to increase family-building awareness and prevent infertility is urgently needed. Recommendations are provided and important knowledge gaps identified to provide professionals, the public, and policymakers with a comprehensive understanding of the role of child-friendly policies.

SEARCH METHODS

A narrative review of the existing literature was performed by invited global leaders who themselves significantly contributed to this research field. Each section of the review was prepared by two to three experts, each of whom searched the published literature (PubMed) for peer reviewed full papers and reviews. Sections were discussed monthly by all authors and quarterly by the review board. The final document was prepared following discussions among all team members during a hybrid invitational meeting where full consensus was reached.

OUTCOMES

Major advances in fertility care have dramatically improved family-building opportunities since the 1990s. Although up to 10% of all children are born as a result of fertility care in some wealthy countries, there is great variation in access to care. The high cost to patients of infertility treatment renders it unaffordable for most. Preliminary studies point to the increasing contribution of fertility care to the global population and the associated economic benefits for society.

WIDER IMPLICATIONS

Fertility care has rarely been discussed in the context of a rapid decrease in world population growth. Soon, most countries will have an average number of children per woman far below the replacement level. While this may have a beneficial impact on the environment, underpopulation is of great concern in many countries. Although governments have implemented child-friendly policies, distinct discrepancies in access to fertility care remain.

Resolving Male Infertility: A Case Report on Treating Obstructive Azoospermia Using SpermMobil in Intracytoplasmic Sperm Injection Procedure

Infertility affects couples worldwide. Among these, obstructive azoospermia (OA) is a common cause. In some cases, the lack of spermatozoa in ejaculation results from blockages in the male reproductive tract. In this case study, we discuss an infertile male diagnosed with OA following three years of unsuccessful attempts at conception. The male had a history of bilateral inguinal hernia repair due to congenital bilateral absence of the vas deferens. Diagnostic assessments confirmed azoospermia. Microscopic epididymal sperm aspiration (MESA) was performed for sperm retrieval due to its efficacy and reduced postoperative pain, testicular atrophy, and decreased testosterone levels. The retrieved sperm was processed using SpermMobil media for intracytoplasmic sperm injection. Following successful fertilization, embryo transfers resulted in a positive pregnancy test. This case highlights the significance of specific treatment approaches for OA, specifically the effectiveness of MESA and SpermMobil in achieving successful outcomes in assisted reproduction technology for male infertility.

Ferritinophagy-mediated ferroptosis of spermatogonia is involved in busulfan-induced oligospermia in the mice

Busulfan, a bifunctional alkylated chemotherapeutic agent, has male reproductive toxicity and induce oligospermia, which is associated with ferroptosis. However, the specific target cells of busulfan-induced oligospermia triggered by ferroptosis are largely elusive, and the detailed mechanisms also require further exploration. In the present study, busulfan (0.6, and 1.2 mM, 48 h) causes ferroptosis in GC-1 spg cells through inducing Fe2+, ROS and MDA accumulation and functional inhibition of Xc-GSH-GPX4 antioxidant system. After inhibition of ferroptosis by Fer-1 (1 μM, pretreatment for 2 h) or DFO (10 μM, pretreatment for 2 h) reverses busulfan-induced destructive effects in GC-1 spg cells. Furthermore, using RNA-seq and Western blotting, we found that busulfan promotes autophagy-dependent ferritin degradation, as reflected by enriching in autophagy, increased LC3 II, Beclin1 and NCOA4, as well as decreased P62 and ferritin heavy chain 1 (FTH1). Ultimately, GC-1 spg cells and Balb/c mice were treated with busulfan and/or 3-MA, the inhibitor of autophagy. The results displayed that inhibition of autophagy relieves busulfan-induced FTH1 degradation and then blocks the occurrence of ferroptosis in GC-1 spg cells and testicular spermatogonia, which subsequently alleviates busulfan-caused testicular damage and spermatogenesis disorders. In summary, these data collectively indicated that ferroptosis of spermatogonia is involved in busulfan-induced oligospermia and mediated by autophagy-dependent FTH1 degradation, identifying a new target for the therapy of busulfan-induced male infertility.

Effects of autonomic nervous system disorders on male infertility

The male reproductive functions are largely regulated by the autonomic nervous system. Male sexual behavior and fertility primarily depend on the normal function of the higher neural centers related to the autonomic nervous system, the hypothalamic-pituitary-gonadal axis, the autonomic nervous components within the spinal cord and spinal nerves, and certain somatic nerves in the pelvic floor. In this review article, we will summarize the role of the autonomic nervous system in regulating male reproductive capabilities and fertility, its impact on male infertility under abnormal conditions, including the role of drug-induced autonomic nervous dysfunctions on male infertility. The main purpose of this article was to provide an overview of the effects of autonomic nervous dysfunction on male reproductive function and shed light on the potential therapeutic target for male infertility.