Clinical characteristics and reproductive outcomes in infertile men with testicular early and late maturation arrest

Multiomics analysis of male infertility

Infertility affects 8-12% of couples globally, and the male factor is a primary cause in approximately 50% of couples. Male infertility is a multifactorial reproductive disorder, which can be caused by paracrine and autocrine factors, hormones, genes, and epigenetic changes. Recent studies in rodents and most notably in humans using multiomics approach have yielded important insights into understanding the biology of spermatogenesis. Nonetheless, the etiology and pathogenesis of male infertility are still largely unknown. In this review, we summarized and critically evaluated findings based on the use of advanced technologies to compare normal and obstructive azoospermia (OA) versus non-obstructive azoospermia (NOA) men, including whole-genome bisulfite sequencing (WGBS), single cell RNA-seq (scRNA-seq), whole exome sequencing (WES), and ATAC-seq. It is obvious that the multiomics approach is the method of choice for basic research and clinical studies including clinical diagnosis of male infertility.

Chronic Immune-Mediated Orchitis Is the Major Cause of Acquired Non-obstructive Azoospermia in Dogs

Azoospermia, the lack of spermatozoa in the ejaculate, is the most common finding in infertile but otherwise healthy male dogs and represents an increasing reproductive health issue in men, too. The diagnosis can be further classified as non-obstructive azoospermia and obstructive azoospermia due to an obstruction of the deferent ducts. Although non-obstructive azoospermia comprises more than half of azoospermic cases in men and is a common cause of infertility in the male dog, knowledge of the underlying etiology and pathophysiology is still strongly limited, and much uncertainty exists about the true incidence and possible treatment options. Therefore, this study aims to investigate and characterize infertile canine patients in detail by combining results of andrological examinations (clinical parameters, semen analysis, bacterial examination of semen, and Brucella canis serology), endocrine analysis (luteinizing hormone, testosterone, estradiol-17ß, and thyroid function), analysis of the alkaline phosphatase in seminal plasma, and histological assessment of testicular biopsies of 10 azoospermic dogs. Our results not only verify non-obstructive etiology for 9/10 cases of canine azoospermia but also further identified significant histopathological changes of the testicular tissue with severely disrupted spermatogenesis, including fibrotic remodeling, vacuolization, Sertoli-cell-only syndrome, tubular shadows, and an increase of the interstitial and vascular area. In addition, three dogs showed local and six dogs generalized immune-cell infiltration, indicating chronic immune-mediated orchitis. Only in one case (no. 1) that no immune cells were found, and obstructive azoospermia was suspected due to low alkaline phosphatase activity. Furthermore, the detection of anti-thyroideal antibodies in two dogs indicates an autoimmune thyroid disease and a correlation between the occurrence of thyroidal disorders and azoospermia. Our results confirm previous findings and contribute additional evidence suggesting that chronic immune-mediated orchitis is the major cause of infertility in dogs. Further studies should focus on uncovering underlying inflammatory processes behind spermatogenic failure in these cases and identify possible treatment options to (re-)initialize spermatogenesis.

Multi-stage screening cell-free seminal mRNAs to diagnose completion of meiosis and predict testicular sperm retrieval in men with non-obstructive azoospermia

BACKGROUND

Differential diagnosis of men with subtypes of non-obstructive azoospermia (NOA) is important for their treatment. Many genes are transcripted during meiosis. We hypothesized that some of these genes can be detected in cell-free seminal mRNAs (cfs-mRNA) and be developed as non-invasive biomarkers for diagnosing NOA subtypes.

OBJECTIVE

To screen cfs-mRNA to diagnose the completion of meiosis and predict successful sperm retrieval (SR) in men with NOA.

MATERIALS AND METHODS

NOA patients who visited our institutes from September 2018 to December 2020 for testicular histopathological diagnosis (n = 109) or testicular SR (n = 92) were screened for participation in the study. Microarray and real-time quantitative PCR were used in five stages to obtain candidate cfs-mRNAs for comparisons between patients with early maturation arrest (eMA, meiosis not completed) and late MA or hypospermatogenesis (meiosis completed), and between NOA patients with successful SR and SR failure.

RESULTS

Twelve cfs-mRNAs were selected based on this comparison between men with eMA and hypospermatogenesis and their gene expression and function information. Of these, AKAP1, BOLL, TCP11, and SETX predominantly derived from testes and germ cells were proposed as candidate cfs-mRNAs. Further quantification in men with NOA demonstrated significantly higher levels of BOLL cfs-mRNA (P < 0.0001) in men with late MA or hypospermatogenesis (n = 23), compared with men with eMA (n = 51); and significantly higher levels (P < 0.0001) in patients with successful SR (n = 44) when compared with patients with SR failure (n = 37). Interestingly, with a similar cutoff value, BOLL cfs-mRNA showed high sensitivity and specificity in diagnosing late MA and hypospermatogenesis (>404 copies/mL) and predicting successful SR (>415 copies/mL). Correlation of BOLL mRNA levels was observed in paired semen and testicular tissues.

DISCUSSION AND CONCLUSIONS

We propose that BOLL cfs-mRNA is a promising non-invasive marker for diagnosing the completion of meiosis and predicting successful testicular SR in men with NOA. This article is protected by copyright. All rights reserved.

Aetiological analysis and diagnosis of reproductive disorders in male dromedary camels

The purpose of this paper was to analyse the aetiology and methods of diagnosing reproductive disorders in male dromedary camels. Male camel infertility manifests as one of three conditions: post-coital infertility (IG), inability to copulate (IC) and lack of sexual desire (LSD). IG is mainly a testicular disorder that is linked to a deteriorated seminogram, arrested spermatogenesis, Sertoli cell-only syndrome and testicular degeneration. For IG diagnosis, semen analysis, testicular biopsy and fine-needle aspiration are gold standards. Testicular ultrasonography was generally inefficient. High serum FSH was found in IG camels with oligo- and azoospermia, implying primary spermatogenesis defects. The testis-expressed protein (TEX101) and the epididymis-expressed protein (ECM1) are reliable biomarkers for distinguishing between obstructive and non-obstructive azoospermia. IC manifests in two forms: phimosis (PHI) and erectile dysfunction (ED). PHI is frequently linked to preputial and penile pathologies, as well as leucocytosis, neutrophilia and elevated nitric oxide metabolites. The majority of camels with ED have normal genital organs, and the condition is associated with an increase in cardiac troponin I. LSD is a rare disorder brought on by hormonal imbalances, high temperatures, stress and debilitating diseases. In conclusion, IG diagnosis necessitates semen analysis, testicular biopsy or fine-needle aspiration, and FSH testing, whereas IC diagnosis requires preputial and penile examinations. Diagnostic aids include serum and seminal biomarkers.

Surgical treatment for male infertility

Given the nature of the multiple causes of male infertility, some of them are «reversible» and can be managed with a surgical procedure to recover, in some cases, the fertilizing capacity of the male reproductive tract. With appropriate use of diagnostic tools and clinical judgement, the physician can identify the ideal candidates for these procedures. Together with the expertise and experience of the surgeon, these treatments can manage to resolve the barrier, and men may become fertile again. In this chapter, we will review some of the most commonly used surgical procedures for the treatment of male infertility and make a brief description of their technical details.

Fertility after the Operation of Cryptorchism in Childhood

Cryptorchism is a congenital anomaly of male genitalia, and is defined as a disorder of lowering testicles into the scrotum. In our study, the quality of sperm and fertility of men who were operated from unilateral or bilateral cryptorchism in childhood were analyzed. According to the age in which they were operated, patients were classified into different time groups, subjected to clinical examination and sperm analysis. A normal sperm count was found: 36.9% of the total number of patients operated from unilateral to bilateral cryptorchism. The highest percentage of normal sperm counts was 73.97%: the data which was found in the group that was operated from one-sided cryptorchism to the end of the second year of life. Regardless of the age of the cryptorchism operation, it is possible to expect a disorder of spermatogenesis.

New insights into the morphological and hormonal characteristics of spermatogenic arrest

The reported sperm retrieval rate (SRR) in patients with nonobstructive azoospermia (NOA) due to spermatogenic arrest (SA) is highly variable in the literature. This discrepancy could be explained by the heterogeneity of testicular tissues. Surprisingly, even though inhibin B levels reflect directly Sertoli cell function; no studies have evaluated this parameter in SA. We aimed to clarify the morphological and biological profile in 158 men with SA. From the total population, patients whose seminiferous tubules diameter was below 165 µm have higher SRR (46.9% vs. 27.4%, p < 0.05), lower inhibin levels and a higher frequency of nonuniform SA (71.9% vs. 38.7%, p < 0.001). On multivariate analysis, patients with late SA and a history of cryptorchidism were positively associated with successful sperm extraction. Patients with successful SRR and uniform SA exhibited inhibin levels twofold lower than those with failed TESE (45 pg/ml vs. 95 pg/ml, p < 0.05), whereas FSH levels were similar in the two groups. In this study, we showed for the first time that the mean diameter of the seminiferous tubules may be of value in the diagnosis of SA. Our results suggest that inhibin levels could be useful in the management of NOA with SA, along with FSH levels and testicular volume.

Distinct prophase arrest mechanisms in human male meiosis

To prevent chromosomal aberrations being transmitted to the offspring, strict meiotic checkpoints are in place to remove aberrant spermatocytes. However, in about 1% of males these checkpoints cause complete meiotic arrest leading to azoospermia and subsequent infertility. Here, we unravel two clearly distinct meiotic arrest mechanisms that occur during prophase of human male meiosis. Type I arrested spermatocytes display severe asynapsis of the homologous chromosomes, disturbed XY-body formation and increased expression of the Y chromosome-encoded gene ZFY and seem to activate a DNA damage pathway leading to induction of p63, possibly causing spermatocyte apoptosis. Type II arrested spermatocytes display normal chromosome synapsis, normal XY-body morphology and meiotic crossover formation but have a lowered expression of several cell cycle regulating genes and fail to silence the X chromosome-encoded gene ZFX. Discovery and understanding of these meiotic arrest mechanisms increases our knowledge of how genomic stability is guarded during human germ cell development.

Summary: Histological examination and transcriptomic analysis of human meiosis-arrested spermatocytes reveals two prophase arrest mechanisms, each associated with distinct gene expression profiles implicating the involvement of different biological processes.

Spermatogenesis in humans and its affecting factors

Spermatogenesis is an extraordinary complex process. The differentiation of spermatogonia into spermatozoa requires the participation of several cell types, hormones, paracrine factors, genes and epigenetic regulators. Recent researches in animals and humans have furthered our understanding of the male gamete differentiation, and led to clinical tools for the better management of male infertility. There is still much to be learned about this intricate process. In this review, the critical steps of human spermatogenesis are discussed together with its main affecting factors.

Experimental methods to preserve male fertility and treat male factor infertility

Infertility is a prevalent condition that has insidious impacts on the infertile individuals, their families, and society, which extend far beyond the inability to have a biological child. Lifestyle changes, fertility treatments, and assisted reproductive technology (ART) are available to help many infertile couples achieve their reproductive goals. All of these technologies require that the infertile individual is able to produce at least a small number of functional gametes (eggs or sperm). It is not possible for a person who does not produce gametes to have a biological child. This review focuses on the infertile man and describes several stem cell-based methods and gene therapy approaches that are in the research pipeline and may lead to new fertility treatment options for men with azoospermia.

Sperm retrieval techniques

Since the advent of intracytoplasmic sperm injection in 1992, sperm retrieval procedures have been routinely employed to treat male infertility owing to azoospermia. With obstructive azoospermia, sperm is potentially harvestable from the vas deferens, epididymis, and testicle using percutaneous and open sperm retrieval procedures that are relatively straightforward and reliable. In nonobstructive azoospermia, sperm is generally found only in the testicles and can often be difficult to retrieve. Several approaches aimed at maximizing sperm yield in this condition have been developed, but only 50% of men with nonobstructive azoospermia will have clinically usable sperm. Multibiopsy testicular sperm extraction (TESE), microdissection TESE, and fine-needle-aspiration map-guided TESE are three common methods currently employed to locate and retrieve sperm in these difficult cases. Other factors that influence the use of surgically retrieved sperm for assisted reproduction include differences in sperm DNA integrity, the expertise of the surgeon and the andrology laboratory, and the described differences in the viability of sperm from different anatomical sources after freezing and thawing.

Azoospermia due to spermatogenic failure

This article summarizes the current literature regarding azoospermia caused by spermatogenic failure. The causes and genetic contributions to spermatogenic failure are reviewed. Medical therapies including use of hormonal manipulation, whether guided by a specific abnormality or empiric, to induce spermatogenesis are discussed. The role of surgical therapy, including a discussion of varicocelectomy in men with spermatogenic failure, as well as an in-depth review of surgical sperm retrieval with testicular sperm extraction and microdissection testicular sperm extraction, is provided. Finally, future directions of treatment for men with spermatogenic failure are discussed, namely, stem cell and gene therapy.

Office-based sperm retrieval for treatment of infertility

This article describes sperm retrieval procedures that may be performed in an office setting. Indications for sperm retrieval, preprocedural preparation, and anesthetic considerations are discussed. Vasal sperm aspiration, percutaneous epididymal sperm aspiration, microsurgical epididymal sperm aspiration, testicular sperm aspiration, conventional, and microdissection testicular sperm extraction are reviewed. Success and complication rates as well as factors that may influence success (histopathology, cancerous cause, Klinefelter syndrome, Y microdeletions, varicocele, and hormone administration) are reviewed.

Severe testicular atrophy does not affect the success of microdissection testicular sperm extraction

PURPOSE

Men with azoospermia and severe testicular atrophy may be counseled to avoid sperm retrieval due to perceived limited success. We evaluated the outcomes of microdissection testicular sperm extraction in men with severe testicular atrophy (volume 2 ml or less).

MATERIALS AND METHODS

We reviewed the records of 1,127 men with nonobstructive azoospermia who underwent microdissection testicular sperm extraction followed by intracytoplasmic sperm injection. They were classified into 3 groups based on average testicular volume, including 2 ml or less, greater than 2 to less than 10 and 10 or greater. Sperm retrieval, clinical pregnancy and live birth rates were calculated. Clinical features evaluated included age, follicle-stimulating hormone level, cryptorchidism history, Klinefelter syndrome, varicocele and testicular histology on diagnostic biopsy.

RESULTS

Testicular sperm were successfully retrieved in 56% of the men. The sperm retrieval rate in those with a testicular volume of 2 ml or less, greater than 2 to less than 10 and 10 or greater was 55%, 56% and 55%, respectively. Clinical pregnancy and live birth rates were similar in men in the 3 groups who underwent sperm retrieval (55.2%, 50.0% and 47.0%, and 47.2%, 43.0% and 42.2%, respectively). Of the 106 men with an average testis volume of 2 ml or less those from whom sperm were retrieved were younger (31.1 vs 35.2 years) and more likely to have a history of Klinefelter syndrome (82.2% vs 55.6%) than men in whom sperm were not found (p <0.05). Men in this group had a higher prevalence of Klinefelter syndrome than men with a testis volume of greater than 2 ml (72.6% vs 5.3%, p <0.0001). Men younger than 30 years with Klinefelter syndrome had a higher sperm retrieval rate than men older than 30 years without Klinefelter syndrome (81.8% vs 33%, p <0.01). There was no cutoff point for age beyond which sperm could not be retrieved in men with small testes. On multivariable analysis younger age was the only preoperative factor associated with successful sperm retrieval in men with small testes (2 ml or less).

CONCLUSIONS

Testicular volume does not affect the sperm retrieval rate at our center for microdissection testicular sperm extraction. Of men with the smallest volume testes those who were younger with Klinefelter syndrome had the highest sperm retrieval rate. Severe testicular atrophy should not be a contraindication to microdissection testicular sperm extraction.