Male Infertility and the Future of In Vitro Fertilization

A Narrative Review Discussing Vasectomy-Related Impact upon the Status of Oxidative Stress and Inflammation Biomarkers and Semen Microbiota

Background: Male contraceptive approaches besides tubal sterilization involve vasectomy and represent the method of choice among midlife men in developing countries thanks to many advantages. However, the subsidiary consequences of this intervention are insufficiently explored since the involved mechanisms may offer insight into a much more complex picture. Methods: Thus, in this manuscript, we aimed to reunite all available data by searching three separate academic database(s) (PubMed, Web of Knowledge, and Scopus) published in the past two decades by covering the interval 2000–2023 and using a predefined set of keywords and strings involving “oxidative stress” (OS), “inflammation”, and “semen microbiota” in combination with “humans”, “rats”, and “mice”. Results: By following all evidence that fits in the pre-, post-, and vasectomy reversal (VR) stages, we identified a total of n = 210 studies from which only n = 21 were finally included following two procedures of eligibility evaluation. Conclusions: The topic surrounding this intricate landscape has created debate since the current evidence is contradictory, limited, or does not exist. Starting from this consideration, we argue that further research is mandatory to decipher how a vasectomy might disturb homeostasis.

Does paternal age affect the live birth rate in donor oocyte cycles? A systematic review and meta-analysis

PURPOSE

While delayed parenthood is increasing worldwide, the effect of paternal age on in vitro fertilization (IVF) outcomes remains unclear. The egg donation model appears to be relevant to studying the independent impact of paternal age on clinical outcome, but the available studies are heterogeneous and contradictory. This systematic review and meta-analysis aimed to assess the relationship between paternal age and live birth rate (LBR) in egg donation cycles.

METHODS

A systematic search of the literature was conducted in PubMed, Embase, and the Cochrane Library from inception to June 30, 2021. All studies on egg donation cycles where LBR is reported according to male age were included. Study selection, bias assessment, and data extraction were performed by two independent reviewers according to the Cochrane methods.

RESULTS

Eleven studies involving 10,527 egg donation cycles were finally included. The meta-analysis showed a slight but significant and linear decrease in LBR with increasing paternal age (estimate - 0.0055; 95% CI (- 0.0093; - 0.0016), p = 0.006), with low heterogeneity (I2 = 25%). No specific threshold was identified. A similar trend toward decreased clinical pregnancy rate with advancing paternal age was found but did not reach statistical significance (p = 0.07).

CONCLUSION

This meta-analysis demonstrates that increasing paternal age is associated with a slight but significant and linear decrease in the live birth rate in egg donation cycles, with no apparent threshold effect. Although this requires further confirmation, this information is important for counseling men who are considering delayed childbearing.

Separating the chaff from the wheat: antibody-based removal of DNA-fragmented sperm

STUDY QUESTION

Is it possible to remove sperm with damaged DNA from a semen sample?

SUMMARY ANSWER

By using immunomagnetic cell sorting that targets the sperm head-bound epididymal sperm-binding protein 1 (ELSPBP1), it was possible to produce an ELSPBP1(-) sperm fraction characterized by consistently lower levels of sperm DNA fragmentation (SDF).

WHAT IS KNOWN ALREADY

In bovines, ELSPBP1 is bound to dead spermatozoa. Human ejaculates with high SDF have increased detected levels of sperm ELSPBP1 when compared to ejaculates with low native SDF.

STUDY DESIGN, SIZE, DURATION

We recruited 267 patients who were referred to the clinic for conjugal infertility. After applying exclusion criteria, such as fever within 90 days of the study, history of systemic diseases, alterations or surgical interventions to the genital tract and use of cigarette or drugs, a total of 133 patients were included. A total of 52 samples were used for the evaluation of sperm ELSPBP1 levels (Sub-study 1), 41 samples for determination of ELSPBP1 location in human sperm (Sub-study 2), and 40 samples for immunomagnetic cell sorting targeting ELSPBP1, to produce ELSPBP1(-) (without ELSPBP1) and ELSPBP1(+) (with ELSPBP1) fractions (Sub-study 3). Samples were collected between July 2016 and September 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In Sub-study 1, sperm ELSPBP1 levels were assessed by western blotting. For Sub-study 2, ELSPBP1 was localized in sperm by immunocytochemistry. Finally, for Sub-study 3, sperm were selected based on incubation of semen samples with antibody-coated magnetic microspheres targeting ELSPBP1. Two fractions were produced (with or without ELSPBP1), and these sub-populations were submitted to an alkaline Comet assay for determination of SDF.

MAIN RESULTS AND THE ROLE OF CHANCE

Men with high SDF presented higher sperm ELSPBP1 levels when compared to the control group (low SDF), while no difference between groups was observed in seminal plasma. ELSPBP1 was located in the head region of human sperm. The ELSPBP1(+) fractions presented high and variable levels of SDF, while their paired ELSPBP(-) fractions presented consistently low SDF.

LIMITATIONS, REASONS FOR CAUTION

This work did not validate the levels of ELSPBP1 in other functional alterations of sperm, such as acrosome integrity or mitochondrial activity. Moreover, this is still a pre-clinical study, intended to demonstrate proof-of-concept that ELSPBP1 selects sperm with low DNA fragmentation; further investigation is warranted to demonstrate safety for use in ART. Sperm fractions were not assessed for sperm vitality. A clinical trial is still necessary for these findings to be extrapolated to outcomes in ART.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings demonstrate that ELSPBP1 is associated with sperm with higher levels of DNA fragmentation. The finding that the sperm membrane can reflect alterations in DNA integrity could give rise to a novel molecular method for sperm preparation prior to use of assisted reproductive procedures. Moreover, the detection of sperm-bound ELSPBP1 could serve as an indirect method for the determination of DNA fragmentation.

STUDY FUNDING/COMPETING INTEREST(S)

L.B.B. was a recipient of a Ph.D. scholarship from the Sao Paulo Research Foundation-FAPESP (process number 2016/05487-3). R.P.B. is a recipient of a Scientific Productivity scholarship from the Brazilian National Council for Scientific and Technological Development-CNPq (process number 306705/2017-6). The authors have no conflict of interest to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Fertility in the aging male: a systematic review

The negative effect of advanced female age on fertility and offspring health is well understood. In comparison, much less is known about the implications of male age on fertility, with many studies showing conflicting results. Nevertheless, increasing evidence suggests that advanced paternal age has negative effects on sperm parameters, reproductive success, and offspring health. Herein, we summarize the current body of knowledge on this controversial topic, with the belief that this review will serve as a resource for the clinicians providing fertility counseling to couples with older male partners.

Prevalence and associated risk factors for anxiety and depression in infertile couples of ART treatment: a cross-sectional study

BACKGROUND

Infertility now is a public health concern and is associated with increased psychological distress.

METHODS

We enrolled 1247 infertile couples and assessed their anxiety and depression status before and during assisted reproductive technology (ART) treatment using the Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS). The Chi-square or fisher's exact test was used to analyze the prevalence of anxiety and depression in infertile couples. Multivariate logistical regression was performed to analyze the risk factors for anxiety and depression.

RESULTS

The prevalence of anxiety was 13.5% and 8.7% (p < 0.05), and that of depression was 9.4% and 7.9% (p = 0.2) in female and male partners, respectively. Female SAS and SDS scores were positively associated with male SAS and SDS scores, respectively (r = 0.52 and r = 0.50, respectively, both p < 0.0001), and were positively associated with their own SDS and SAS scores, respectively (r = 0.63 and r = 0.62, respectively, both p < 0.0001). Their own depression or partners' anxiety was associated with the anxiety, and their own anxiety or partners' depression was associated with the depression in infertile couples. No children, unemployment, and low education level were also associated with female anxiety. SAS and SDS scores were significantly decreased during ART treatment.

CONCLUSIONS

Females were more vulnerable to having anxiety than males in infertile couples. Anxiety and depression in infertile couples could interact, therefore, anxiety and depression would be simultaneously counseled, and their partners also should be given supportive psychotherapy.

TRIAL REGISTRATION

It was an observational study and had no health care interventions on participants. So it was not registrated.

Seminal and testicular microbiome and male fertility: A systematic review

Supplemental Digital Content is available in the text

Microbiome is of upmost importance for the well-being of the human body. Based on culture and PCR methods, seminal flora has been pointed as a potential cause for some of the unexplained male infertility.

This is a systematic review about the effect of seminal microbiota studied by Next Generation Sequencing techniques on sperm quality and male fertility, performed according to PRISMA statement.

Nine articles were included. Results of different studies are diverse. It seems that microbiota may a play a role in seminal quality and further male fertility, but the way this effect is modulated is still to be unknown. Lactobacillus spp seemed to play a beneficial role in semen quality, but the role of the remaining bacteria is unclear.

Due to the lack of research and the incongruence of the results so far, the effect of microbiota on seminal quality is still unclear.

The current perspective on genetic and epigenetic factors in sperm maturation in the epididymis

Male infertility affects approximately 30% of infertile couples. As spermatozoa mature in the epididymal lumen, their potential for mobility increases, and their protein, lipid and small RNA (sRNA) content changes, whereas capacitation and fertilisation take place in the female reproductive tract. Both of the latter processes are affected by maturation, because impaired maturation causes premature capacitation and fertilization. The epididymis produces a suitable environment for sperm maturation via ion transport, vesicle secretion and protein matrix formation. The microenvironment for sperm maturation varies in three broad segments: the caput, the corpus and the cauda epididymis. Epididymosomes transfer proteins, lipids and sRNAs from the epididymal epithelium to spermatozoa and genetic alterations of epididymal genes can lead to decreased sperm motility, morphological abnormalities of spermatozoa and subfertility. Genetic factors are involved in all aetiological categories in male infertility. However, studies conducted on the genes involved in epididymal functions are limited. The sRNA content of spermatozoa changes during epididymal migration, and these sRNAs play a role in embryo development and epigenetic inheritance. This review aims to clarify the role of the epididymal epithelium in the maturation of spermatozoa in light of the current molecular genomic knowledge.