A novel application of cell-free seminal mRNA: non-invasive identification of the presence of germ cells or complete obstruction in men with azoospermia

Isolation of CD63-positive epididymosomes from human semen and its application in improving sperm function

Extracellular vesicles (EVs) are highly heterogeneous, and different EV subpopulations from various origins mediate different biological effects. The separation of different subpopulations of EVs from mixtures is critical but challenging. Epididymosomes are secreted by the epididymal epithelium and play a key role in sperm maturation and function. However, limited access to human epididymal tissue and epididymal fluid has hampered further study of epididymosomes and their potential clinical applications. Here, we established a novel strategy based on flow cytometry sorting to isolate human CD63-positive epididymosomes from ejaculate. We identified CD52, a membrane-located protein expressed exclusively in the epididymis, as the sorting marker for human epididymosomes. Then, CD63-positive epididymosomes were isolated from human semen using a flow cytometry sorting instrument and concentrated. Additionally, we observed that isolated CD63-positive epididymosomes improved sperm function more than other CD63-positive seminal EV subpopulations did, demonstrating the successful isolation of a subpopulation of epididymosomes from human semen and their potential application in the clinic.

Andrology laboratory technique for analysis of semen in men with azoospermia

ABSTRACT

Discovery of spermatozoa during the 17th century led to developing technologies for semen analysis in the early 1900s, and then, standard techniques were implemented during the 20th century. Semen analysis has a pivotal role in the male infertility evaluation, and azoospermia is an important finding. Azoospermia is identified in 15% of infertile men. However, the accurate laboratory assessment of azoospermia poses certain technical challenges. Laboratories currently perform semen assessment with great variability; thus, a standard method should be used. Planning suitable management and determining the cause of infertility require a precise evaluation of azoospermia. This review aims to address the definition of azoospermia and highlight laboratory methods in the assessments of azoospermia. Basic methods such as centrifugation, repeat pellet analysis, and staining and advanced methods such as genetic testing and biomarkers have been discussed. These methods have helped in standardizing the protocol for accurate azoospermia assessments with less variability.

Promising novel biomarkers and therapy targets: The application of cell-free seminal nucleotides in male reproduction research

Liquid biopsy has the advantage of diagnosing diseases in a non-invasive manner. Seminal plasma contains secretions from the bilateral testes, epididymides, seminal vesicles, bulbourethral glands, and the prostate. These organs are relatively small and contain delicate tubes that are prone to damage by invasive diagnosis. Cell-free seminal nucleic acids test is a newly emerged item in liquid biopsy. Here, we present a comprehensive overview of all known cell-free DNA and cell-free RNAs (mRNA, miRNA, lncRNA, circRNA, piRNA, YRNA, tsRNA, etc.) and discuss their roles as biomarker candidates in liquid biopsy. With great advantages, including high stability, sensitivity, representability, and non-invasiveness, cell-free DNA/RNAs may be developed as promising biomarkers for the screening, diagnosis, prognosis, and follow-up of diseases in semen-secreting organs. Moreover, RNAs in semen may participate in important processes, including sperm maturation, early embryo development, and transgenerational disease inheritance, which may be developed as potential treatment targets for future clinical use.

Establishment of a co-analysis system for personal identification and body fluid identification: a preliminary report

Analysis of genetic markers can provide clues for case investigation. Short tandem repeat (STR) detection and analysis are widely used for both personal identification and parentage testing. However, DNA analysis currently cannot provide sufficient information for body fluid identification. Tissue or cell sources of samples can be identified by detecting body fluid-specific mRNA markers, which have been studied thoroughly. Integrating STR profiling and mRNA expression patterns can provide more information than conventional methods for investigations and the reconstruction of crime scenes; this can be achieved by DNA/RNA co-extraction technology, which is economical, efficient, and suitable for low-template samples. Here, we propose a co-analysis system based on the PowerPlex 16 kit. This system can simultaneously amplify 25 markers, including 15 STRs, one non-STR amelogenin, and nine mRNA markers (three blood-specific, two saliva-specific, two semen-specific, and two housekeeping gene markers). The specificity and sensitivity of the co-analysis system were determined and aged and degraded samples were used to validate the stability of the co-analysis system. Finally, different DNA/RNA ratios and various carriers were evaluated. The results showed that the DNA/RNA co-analysis system correctly identified different types of body fluid stains. The STR profiles obtained using the co-analysis system were identical to those obtained using the PP16 kit, which demonstrates that the mRNA primers used did not affect STR profiling. Complete STR and mRNA profiles could be obtained from 1/8 portions of buccal swabs, 1/16 portions of swabs of blood and semen samples, 0.1 cm² of blood samples, 0.25 cm² of semen samples, and 1.0 cm² saliva samples. Additionally, our findings indicate that complete STR and mRNA profiles can be obtained with this system from blood and semen samples when the DNA/RNA ratio is 1:1/32. This study suggests that the co-analysis system could be used for simultaneous personal identification and body fluid identification.

Evaluation of cell-free seminal mRNA for the diagnosis of obstruction as the cause of azoospermia in infertile men: A prospective cohort study

Differentiating obstructive (OA) from non-obstructive (NOA) azoospermia is clinically important in managing infertile men. Classically, the differentiation has been based on clinical, hormonal and histological analysis. Histological tests are invasive and may miss spermatogenic areas. Seminal fluid can serve as a medium to assess the status of spermatogenesis and presence or absence of certain markers can help diagnosing and differentiating azoospermia. We evaluated the role of cell-free seminal markers: DDX4, PRM1 and PRM2 in diagnosing and differentiating between OA and NOA and classifying their subtypes. We observed DDX4 was more sensitive for NOA compared with OA. Among various subtypes of NOA, DDX4 positivity was higher in patients with maturation arrest and hypospermatogenesis compared with Sertoli cell only syndrome. PRM1 and PRM2 had very low positivity rate for any meaningful comparison. Seminal cell-free markers can serve as non-invasive tests in diagnosing and differentiating etiologies of azoospermia but their validity needs to be proved in long-term trials with more refined molecular techniques.

X chromosome-linked genes in the mature sperm influence semen quality and fertility of breeding bulls

The role of sperm expressed X-linked genes on bull fertility has not been studied in detail. The objective of the present study was to assess the influence of X-linked genes on the sperm functional parameters and field fertility rate in the Holstein Friesian cattle (n = 12) and Murrah buffalo (n = 7) bulls. The enrichment analysis (cattle = 8; buffalo = 8) of the X-linked genes was carried out using retrospective RNA-seq data and mRNA expression levels of functionally relevant genes were validated using the RT-qPCR. The mRNA expression levels of these genes were functionally associated with sperm attributes and field fertility rate. The sperm transcriptome studies revealed that the total number of expressed genes and the transcript content of the X-linked genes in the mature sperm were very low in both species, and only 23.31% of these genes were commonly expressed between them. The transcript pool corresponding to the X-linked genes represents embryonic organ development (p = 0.03) and reproduction (p = 0.02) processes in cattle and buffalo sperm, respectively. The mRNA expression levels of X-linked genes, RPL10 and ZCCHC13 in cattle; AKAP4, TSPAN6, RPL10 and RPS4X in buffalo were significantly (p < 0.05) correlated with sperm kinematics. Importantly, the mRNA expression levels of the genes RPL10 (r = -0.68) and RPS4X (r = 0.81) had a significant correlation with the field fertility rate in cattle and buffalo, respectively. Multivariate regression models and receiver operating curve analysis suggest that the mRNA expression levels of X-linked genes may be useful in predicting bull fertility. The study indicates that sperm-expressed X-linked genes influence semen quality and field fertility rate in both cattle and buffalo.

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.

Anatomical Transcriptome Atlas of the Male Mouse Reproductive System During Aging

The elderly males undergo degenerative fertility and testicular endocrine function that jeopardize the reproductive health and well-being. However, the mechanisms underlying reproductive aging are unclear. Here, we tried to address this by investigating the phenotypes and transcriptomes of seven regions of the male mouse reproductive tract: the testis, efferent ductules, initial segment, caput, corpus and cauda epididymidis, and vas deferens, in adult (3 months) and aged (21 months) mice. Quantitative PCR, immunohistochemistry, immunofluorescent staining, and enzyme-linked immunosorbent assay were performed for the analysis of gene expression in mice, human tissues, and semen samples. Aged male mice showed both systematic and reproductive changes, and remarkable histological changes were detected in the testis and proximal epididymis. Transcriptomes of the male reproductive tract were mapped, and a series of region-specific genes were identified and validated in mouse and/or human tissues, including Protamine 1 (Prm2), ADAM metallopeptidase domain 28 (Adam28), Ribonuclease A family member 13 (Rnase13), WAP four-disulfide core domain 13 (Wfdc13), and Wfdc9. Meanwhile, age-related transcriptome changes of different regions of the male reproductive tract were characterized. Notably, increased immune response was functionally related to the male reproductive aging, especially the T cell activation. An immune response-associated factor, phospholipase A2 group IID (Pla2g2d), was identified as a potential biomarker for reproductive aging in mice. And the PLA2G2D level in human seminal plasma surged at approximately 35 years of age. Furthermore, we highlighted Protein tyrosine phosphatase receptor type C (Ptprc), Lymphocyte protein tyrosine kinase (Lck), Microtubule associated protein tau (Mapt), and Interferon induced protein with tetratricopeptide repeats 3 (Ifit3) as critical molecules in the aging of initial segment, caput, caput, and cauda epididymidis, respectively. This study provides an RNA-seq resource for the male reproductive system during aging in mice, and is expected to improve our understanding of male reproductive aging and infertility.

Liquid biopsy: state of reproductive medicine and beyond

Liquid biopsy is the process of sampling and analyzing body fluids, which enables non-invasive monitoring of complex biological systems in vivo. Liquid biopsy has myriad applications in health and disease as a wide variety of components, ranging from circulating cells to cell-free nucleic acid molecules, can be analyzed. Here, we review different components of liquid biopsy, survey state-of-the-art, non-invasive methods for detecting those components, demonstrate their clinical applications and discuss ethical considerations. Furthermore, we emphasize the importance of artificial intelligence in analyzing liquid biopsy data with the aim of developing ethically-responsible non-invasive technologies that can enhance individualized healthcare. While previous reviews have mainly focused on cancer, this review primarily highlights applications of liquid biopsy in reproductive medicine.

Omics in Seminal Plasma: An Effective Strategy for Predicting Sperm Retrieval Outcome in Non-obstructive Azoospermia

Non-obstructive azoospermia (NOA) is a severe form of male factor infertility resulting from the impairment of sperm production. Surgical sperm retrieval followed by intracytoplasmic sperm injection (ICSI) is the only alternative for NOA patients to have their own genetic children. Nevertheless, due to an approximately 50% chance of success, harvesting sperm from these patients remains challenging. Thus, discovering noninvasive biomarkers, which are able to reliably predict the probability of sperm acquisition, not only can eliminate the risk of surgery but also can lower the costs of NOA diagnosis and treatment. Seminal plasma is the non-cellular and liquid portion of the ejaculate that consists of the secretions originating from testes and male accessory glands. In past years, a wide range of biomolecules including DNAs, RNAs, proteins, and metabolic intermediates have been identified by omics techniques in human seminal plasma. The current review aimed to briefly describe genomic, transcriptomic, proteomic, and metabolomic profiles of human seminal plasma in an attempt to introduce potential candidate noninvasive biomarkers for sperm-retrieval success in men with NOA.

Unraveling epigenomic abnormality in azoospermic human males by WGBS, RNA-Seq, and transcriptome profiling analyses

PURPOSE

To determine associations between genomic DNA methylation in testicular cells and azoospermia in human males.

METHODS

This was a case-control study investigating the differences and conservations in DNA methylation, genome-wide DNA methylation, and bulk RNA-Seq for transcriptome profiling using testicular biopsy tissues from NOA and OA patients. Differential methylation and different conserved methylation regions associated with azoospermia were identified by comparing genomic DNA methylation of testicular seminiferous cells derived from NOA and OA patients.

RESULTS

The genome methylation modification of testicular cells from NOA patients was disordered, and the reproductive-related gene expression was significantly different.

CONCLUSION

Our findings not only provide valuable knowledge of human spermatogenesis but also paved the way for the identification of genes/proteins involved in male germ cell development. The approach presented in this report provides a powerful tool to identify responsible biomolecules, and/or cellular changes (e.g., epigenetic abnormality) that induce male reproductive dysfunction such as OA and NOA.

Could analysis of testis-specific genes, as biomarkers in seminal plasma, predict presence of focal spermatogenesis in non-obstructive azoospermia?

Cell-free seminal mRNA (cfs-mRNA) exists in the human ejaculate that is proposed as a potential noninvasive procedure to prognosis pathophysiological conditions. This study applied cfs-mRNA of ESX1, ZMYND15 and its target haploid genes (TNP1 and PRM1) to identify the presence of spermatozoa in men with azoospermia. This study included 35 semen samples from 16 normozoospermic and 19 nonobstructive azoospermic individuals. Expression levels of target genes were determined by real-time reverse transcription-polymerase chain reaction using ΔΔCt method. The expression level of these genes (ZMYND15, TNP1 and PRM1) was significantly decreased in semen samples of nonobstructive azoospermia compared to normozoospermia. Similarly, the expression level of TNP1 and PRM1 was significantly decreased in the sample with negative sperm (SR-) versus positive sperm retrieval (SR+). The expression level of these genes may have the potential for prediction of successful sperm retrieval with high sensitivity and specificity according to the receiver operating characteristics (ROC) curve analysis.

Forensic Spermatozoa Detection

Semen is crucial evidence for some sex crimes, with its sole confirmation being sperm detection. The success of sperm detection is dependent on all levels of preanalytic and analytic procedures. Specimen collection must be performed by well-trained and competent forensic physicians as well as forensic nurses, with preservation done properly before laboratory transfer. Laboratory procedures should consider archival sperm identification, by visualization, with adequate amounts separated from other cells to obtain male DNA profiles. Differential extraction is robust and accepted as the forensic standard but is time consuming and may result in male DNA loss. Thus, alternative methods and microdevices have been developed. Challenges in sperm isolation from vaginal or buccal epithelium mixes and discrimination in multiperpetrator cases have been overcome by single-cell profiling; however, problems inherent in identical twin discrimination and azoospermia have yet to be solved. Epigenetics and future molecular biomarkers may hold the key; therefore, all laboratory processes must consider DNA and RNA protection. Long-term specimen preservation should be done when possible in light of future confirmatory tests.

Cellular origin of microRNA-371a-3p in healthy males based on systematic urogenital tract tissue evaluation

BACKGROUND

The microRNA-371a-3p (miR-371a-3p) has been reported to be an informative liquid biopsy (serum and plasma) molecular biomarker for both diagnosis and follow-up of patients with a malignant (testicular) germ cell tumor ((T)GCT). It is expressed in all histological cancer elements, with the exception of mature teratoma. However, normal testis, semen, and serum of males with a disrupted testicular integrity without a TGCT may contain miR-371a-3p levels above threshold, of which the cellular origin is unknown.

OBJECTIVES

Therefore, a series of relevant tissues (frozen and formalin-fixed paraffin-embedded (FFPE), when available) from the complete male urogenital tract (i.e., kidney to urethra and testis to urethra) and semen was investigated for miR-371a-3p levels using targeted quantitative RT-PCR (qRT-PCR).

MATERIALS AND METHODS

In total, semen of males with normospermia (n = 11) and oligospermia (n = 3) was investigated, as well as 88 samples derived from 32 different patients. The samples represented one set of tissues related to the entire male urogenital tract (11 anatomical locations), three sets for 10 locations, and four sets for six locations.

RESULTS

All testis parenchyma (n = 17) cases showed low miR-371a-3p levels. Eight out of 14 (57%) semen samples showed detectable miR-371a-3p levels, irrespective of the amount of motile spermatozoa, but related to sperm concentration and matched Johnsen score (Spearman's rho correlation coefficient 0.849 and 0.871, p = 0.000, respectively). In all other tissues investigated, miR-371a-3p could not be detected.

DISCUSSION

This study demonstrates that the miR-371a-3p in healthy adult males is solely derived from the germ cell compartment.

CONCLUSIONS

The observation is important in the context of applying miR-371a-3p as molecular liquid biopsy biomarker for diagnosis and follow-up of patients with malignant (T)GCT. Moreover, miR-371a-3p might be an informative seminal biomarker for testicular germ cell composition.

CFTR mutation compromises spermatogenesis by enhancing miR-15b maturation and suppressing its regulatory target CDC25A†

MicroRNAs (miRNAs) have recently been shown to be important for spermatogenesis; both DROSHA and Dicer1 KO mice exhibit infertility due to abnormal miRNA expression. However, the roles of individual miRNAs in spermatogenesis remain elusive. Here we demonstrated that miR-15b, a member of the miR-15/16 family, is primarily expressed in testis. A miR-15b transgenic mouse model was constructed to investigate the role of miR-15b in spermatogenesis. Impaired spermatogenesis was observed in miR-15b transgenic mice, suggesting that appropriate expression of miR-15b is vital for spermatogenesis. Furthermore, we demonstrated that overexpression of miR-15b reduced CDC25A gene post-transcriptional activity by targeting the 3′-UTR region of CDC25A, thus regulating spermatogenesis. In vitro results further demonstrated that a mutation in CFTR could affect the interaction between Ago2 with Dicer1 and that Dicer1 activity regulates miR-15b expression. We extended our study to azoospermia patients and found that infertile patients have a significantly higher level of miR-15b in semen and plasma samples. Taken together, we propose that CFTR regulation of miR-15b could be involved in the post-transcriptional regulation of CDC25A in mammalian testis and that miR-15b is important for spermatogenesis.

VASA mRNA (DDX4) detection is more specific than immunohistochemistry using poly- or monoclonal antibodies for germ cells in the male urogenital tract

VASA, also known as DDX4, is reported to be specifically expressed in cells belonging to the germ cell lineage, both in males and females. Therefore, it could be an informative protein biomarker to be applied on semen to differentiate between obstructive and nonobstructive azoospermia (OA and NOA, respectively). In addition, it could be of value to predict sperm retrieval based on testicular sperm extraction. Immunocytochemistry of proven OA semen using both polyclonal and monoclonal antibodies against VASA showed positive staining of both cells and cell sized particles. This is spite of being the absolute negative controls, completely lacking germ lineage derived cells and material. In order to identify the source of the VASA-positive material, a detailed screen of different anatomical parts of the whole male urogenital tract was performed of multiple cases using immunohistochemistry.The polyclonal antibody stained, besides the expected germ cells in the testis, epithelium of the bladder and the seminal vesicles. The monoclonal antibody only stained the latter. To investigate whether the immunohistochemical staining is associated with the presence of the corresponding VASA mRNA, samples of seminal vesicles, bladder, testis, and semen (with and without germ cells) were investigated using the specific quantitative reverse transcription-polymerase chain reaction (qRT-PCR) on 42 samples. A positive result was detected in testis and semen containing germ cells (n = 10 and 8), being negative in semen without germ cells (n = 11), bladder (n = 3), and seminal vesicles (n = 10).Two commercially available VASA antibodies (mono- and polyclonal) are not specific. In contrast, VASA-mRNA evaluation, using qRT-PCR, is specific for the presence of germ cells, therefore, is an interesting molecular biomarker for germ cell detection in semen.

Dysregulation of an X-linked primate-specific epididymal microRNA cluster in unexplained asthenozoospermia

Asthenoszoopermia, characterized by reduced sperm motility, is one of the primary forms of male infertility. Whereas most cases were diagnosed into unexplained asthenozoospermia (UA) because the etiology cannot be identified. In animal models, epigenetic dysregulation in epididymis can impair sperm maturation and result in asthenozoospermia. However, researches of epididymal epigenetic regulation on humans are impeded by the difficulty in obtaining epididymal tissues. We previously identified cell-free seminal microRNAs predominately derived from epididymis in human ejaculate. In the present study, these microRNAs were used to screen and validate the microRNA dysregulation in men with UA, which were divided into screening set and validation set. The expression of five miRNAs (miR-891b, miR-892b, miR-892a, miR-888 and miR-890) was found and confirmed to be dysregulated in men with UA. Interestingly, these five miRNAs belong to a primate-specific miRNA cluster located on the X chromosome with epididymis specific expression. Moreover, obvious coherent dysregulation of these miRNAs were observed in 13% men with UA. Regression analysis demonstrated that levels of these miRNAs were significantly correlated with progressive sperm motility. Functions and pathways of predicted target genes of this cluster suggested its role in sperm maturation. Dysregulation of this miRNA cluster might be an epigenetic basis for some patients with UA. We also showed a noninvasive and feasible approach to get epigenetic information of human epididymis.

Cell-free and intracellular nucleic acids: new non-invasive biomarkers to explore male infertility

Male infertility is a devastating problem that affects many couples worldwide. However, the molecular mechanisms and causes of idiopathic male infertility remain unclear. Circulating cell-free nucleic acids have an important role in human physiology and emerging evidence suggests that they play a role in male infertility. This review summarizes recent results on cell-free and intracellular nucleic acids in male infertility and discusses their potential use as biomarkers of male infertility in the clinical practice.

Does detection of DDX4 mRNA in cell-free seminal plasma represents a reliable noninvasive germ cell marker in patients with nonobstructive azoospermia?

This study aimed to investigate the potential application of DDX4 gene expression in cell-free seminal mRNA as a noninvasive biomarker for the identification of the presence of germ cells in men with nonobstructive azoospermia and to correlate this factor with testicular biopsy. Male reproductive organ-specific genes were chosen: DDX4, which is a germ cell-specific gene and transglutaminase 4, which is a prostate-specific gene that was used as a control gene. Thirty-nine azoospermic males and twenty-eight normospermic fertile males (serving as a control group) participated in the study. Histopathological examination of testicular biopsies categorised azoospermic males into 20.5% with maturation arrest, 17.9% with incomplete Sertoli cell-only syndrome and 61.5% with complete Sertoli cell-only syndrome. Using real-time polymerase chain reaction, positivity for DDX4 gene was detected in 17 of 39 males with NOA which was due to maturation arrest in 35.3% (n = 6/17) of cases, due to incomplete Sertoli cell only in 23.5% (n = 4/17) and due to complete Sertoli cell only in 41.2% (n = 7/17). The study recommends joint utilisation of molecular transcripts as noninvasive biomarkers and histopathological examination of testicular biopsies in management of cases with azoospermia of the nonobstructive type.

Identification and characterization of human testis derived circular RNAs and their existence in seminal plasma

Circular RNAs (circRNAs) have emerged as novel molecules of interest in gene regulation as other noncoding RNAs. Though they have been explored in some species and tissues, the expression and functions of circRNAs in human reproductive systems remain unknown. Here we revealed the expression profiles of circRNAs in human testis tissue using high-throughput sequencing. The conformation of these testis-derived circRNAs in seminal plasma was also investigated, aiming to provide a non-invasive liquid biopsy surrogate for testicular biopsy. We predicted >15,000 circRNAs in human testis, with most of them (10,792; 67%) new. In all the 5,928 circRNA forming genes, 1,017 are first reported by us to generate circRNAs. Interestingly, these genes are mostly related to spermatogenesis, sperm motility, fertilization, etc. The sequence feature, chromosome location, alternative splicing and other characteristics of the circRNAs in human testis were also explored. Moreover, we found that these testis-derived circRNAs could be stably detected in seminal plasma. Most of them were probably bound with proteins in seminal plasma and were very stable at room temperature. Our work has laid the foundations to decipher regulation mechanisms of circRNAs in spermatogenesis and to develop circRNAs as novel noninvasive biomarkers for male infertile diseases.

Seminal plasma HSPA2 mRNA content is associated with semen quality

PURPOSE

Cell-free mRNAs (cfmRNAs) were quantitatively measured in human seminal plasma and its relationship with semen quality was investigated.

METHODS

Herein, a prospectively, controlled investigation was performed to study seminal plasma HSPA2 and uPA cfmRNA alterations between 21 asthenozoospermic patients and 16 normozoospermic individuals. Standard semen analysis was performed and seminal plasma cfmRNAs content was measured by real-time quantitative PCR. In addition, the regression analysis between seminal plasma cfmRNAs expression and semen parameters was performed.

RESULTS

Seminal plasma HSPA2, but not uPA cfmRNA indicated significant difference between normozoospermia and asthenozoospermia men (P = 0.02444 and 0.07811, respectively). Negative correlation between HSPA2 cfmRNA and sperm motility (R (2) = 0.213, P = 0.004) as well as sperm concentration (R (2) = 0.133, P = 0.026) were revealed. However, no correlation was found between seminal plasma uPA cfmRNA content and semen parameters.

CONCLUSIONS

Our data suggest that seminal plasma HSPA2 cfmRNA is different between asthenozoospermic and normozoospermic individuals and it might be an indicator for semen quality.

Potential confounding factors in measurement of specific cell-free seminal mRNAs and microRNAs derived from human reproductive organs

Cell-free seminal RNA (cfs-RNA) is mixed transcripts derived from male reproductive organs, and is potential biomarker for the research and diagnosis of male reproductive-related diseases. However, some clinical factors, including age, asymptomatic Ureaplasma urealyticum (UU) infection, scrotal heat stress, abstinence period, and the storage condition of semen samples, may interfere with sperm parameters and the measurement of seminal biomarkers. Accordingly, this study was designed to evaluate the effect of above clinical factors on the measurement of cfs-RNA, aiming to lay a foundation for its research use and potential clinical application. Semen samples were collected according to the selected clinical factors. Cell-free seminal plasma was obtained by centrifugation and total RNA was extracted with TRIzol LS. Selective male reproductive organ-specific cfs-mRNAs and cfs-miRNAs were quantified by quantitative real-time PCR. The concentration and total amount of cfs-mRNAs and cfs-miRNAs in one ejaculate were calculated and compared. ACTB, DDX4 (testis-specific), WFDC9 (epididymis-specific), and miR-514a-3p (testis-specific) significantly increased after scrotal heat stress. SEMG1 (seminal vesicle-specific) showed declining tendency with the prolonged abstinence period. Age, asymptomatic UU infection, and the storage condition showed no significant impact on the measurement of cfs-RNA. These results indicate that scrotal heat stress significantly interfere with the selected cfs-RNA derived from the testis and epididymis, and abstinence period may affect the yield of cfs-mRNA from seminal vesicle, while other clinical factors has no significant impact on the measurement. Thus, heat exposure and abstinence period should be considered for the cfs-RNA measurement in its research or clinical application.

Discrimination and characterization of Sertoli cell-only syndrome in non-obstructive azoospermia using cell-free seminal DDX4

Cell-free seminal mRNA (cfs-mRNA) contains testis-specific transcripts from bilateral testes. This study determined the presence of DEAD box polypeptide 4 (DDX4) in cfs-mRNA to identify and characterize the incidence of Sertoli cell-only (SCO) syndrome in men with non-obstructive azoospermia (NOA). DDX4 cfs-mRNA was determined in 315 men with NOA, and compared with testicular samples obtained by microdissection from 19 NOA patients. Karyotype and azoospermia factor microdeletion analysis were performed, and clinical features were evaluated. Negative DDX4 cfs-mRNA suggestive of SCO was found in 13.7% of NOA patients, with a similar incidence in NOA men with known genetic causes and those without known genetic causes. DDX4 cfs-mRNA was absent in 44% of SCO cases diagnosed by testicular histopathology, but present in all patients presenting with maturation arrest or hypospermatogenesis. Furthermore, 84.2% of NOA men with DDX4 cfs-positive mRNA had a DDX4-positive testicular sample. In NOA men without genetic causes, SCO patients discriminated by negative DDX4 cfs-mRNA showed different clinical features when compared with non-SCO cases. These results suggest that the evaluation of DDX4 cfs-mRNA is more accurate than testicular histopathology in discriminating SCO, and also permits the identification of a specific group of NOA men with distinct clinical features.

Changes in mitotic reorientation and Wnt/AR signaling in rat prostate epithelial cells exposed to subchronic testosterone

The aim of the present study was to investigate the changes in mitotic reorientation and relative differential gene expression in rat prostate epithelial cells following long-term exposure to testosterone propionate (TP). Sprague-Dawley rats were randomly divided into two groups as follows: TP group, which received 3.7 mg/kg/day TP for 30 days (n=10); and control group, in which rats were injected with olive oil (n=10). Microscopic analysis of the prostate tissue was performed by immunohistochemical analysis and hematoxylin and eosin staining. Differential gene expression analysis was performed via gene microarray, and a total of five genes (Dkk3, Ran, Fas, Tgm4 and Wnt2) were selected and their expression levels were verified using reverse transcription-polymerase chain reaction. For rats treated with TP, mitosis was significantly reoriented, becoming parallel to the basement membrane. By contrast, in the control group cells mitotic orientation remained perpendicular to the basement membrane. Genes such as Ran and Tgm4 in the androgen receptor (AR) signaling pathway and Wnt2 in the Wnt signaling pathway, were upregulated following treatment with TP. Conversely, the Dkk3 and Fas genes were downregulated following treatment with TP. In conclusion, mitotic orientation of prostate epithelial cells was altered following long-term administration of TP. Wnt and AR signaling pathways influenced cell proliferation and may have participated in the mitotic orientation change.

ESX1 mRNA expression in seminal fluid is an indicator of residual spermatogenesis in non-obstructive azoospermic men

STUDY QUESTION

Is the presence of ESX1 mRNA in seminal fluid (SF) an indicator of residual spermatogenesis in men with non-obstructive azoospermic (NOA)?

SUMMARY ANSWER

ESX1 mRNA in SF is a suitable molecular marker for predicting the presence of residual spermatogenesis in testis.

WHAT IS KNOWN ALREADY

ESX1 is an X-linked homeobox gene whose expression in testis is restricted to germ cells. We previously reported, in the testicular biopsies from azoospermic men, a positive correlation between the presence of ESX1 mRNA and residual spermatogenesis.

STUDY DESIGN, SIZE, DURATION

We investigated ESX1 mRNA expression in 70 testicular fragments (TF) and 56 (SF) of 70 NOA men. As controls, we analyzed 8 TF from men with obstructive azoospermic (OA) and 9 SF from normozoospermic men. For all patients we considered the histological classification of testis biopsies and the recovery of spermatozoa by surgical procedures.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Relative ESX1 mRNA expression was evaluated by quantitative RT-PCR using the ΔΔCt method. The results were compared with the recovery of spermatozoa at surgery.

MAIN RESULTS AND THE ROLE OF CHANCE

In TF from NOA patients we found that: (i) ESX1 mRNA level was significantly decreased as the severity of spermatogenic defects increased (P < 0.0001, one-way analysis of variance); (ii) the presence of ESX1 mRNA can predict the success of sperm retrieval (sensitivity: 80%). In SF from NOA patients we found that: (i) ESX1 mRNA was present in 78.5% of NOA men; (ii) the presence of ESX1 mRNA could predict the success of sperm retrieval (sensitivity: 84%).

LIMITATIONS, REASONS FOR CAUTION

Spermatozoa were recovered at surgery in 5 out of 12 patients whose SF was negative for ESX1 mRNA expression. We think that discrepancies between molecular and clinical results could be reduced by analyzing more than one ejaculate from each man.

WIDER IMPLICATIONS OF THE FINDINGS

The data confirm that the ESX1 transcript in the semen of men with NOA is a suitable molecular marker for predicting the presence of residual foci of spermatogenesis in the testis. The implication of these results is that some patients 'with azoospermia', although having a severe impairment of spermatogenesis, could still maintain residual foci of spermatogenesis in limited areas of the testes, not always recovered by surgery.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico: Ricerca Corrente [grant number RC2014/519-02] to M.M. and from ASM onlus 2010-2011 to M.M. The authors declare that they have no conflict of interest.

Evaluation of forensic examination of extremely aged seminal stains

The results of forensic tests, such as semen identification and short tandem repeat (STR) analysis of extremely aged seminal stains from unsolved sex crimes can provide important evidence. In this study we evaluated whether current forensic methods could be applied to seminal stains that were stored at room temperature for 33-56years (n=2, 33years old; n=1, 41years old; n=1, 44years old; n=1, 56years old). The prostatic acid phosphatase (SM-test reagent), microscopic (Baecchi stain method) and semenogelin (RSID™ Semen Laboratory Kit) tests were performed as discriminative tests for semen. In addition, the mRNA levels of the semen-specific proteins semenogelin 1 (SEMG1) and protamine 2 (PRM2) were investigated. STRs were analyzed using the AmpFlSTR® Identifiler™ PCR Amplification Kit. All samples were positive in the prostatic acid phosphatase and semenogelin tests, and sperm heads were identified in all samples. The staining degree of the aged sperm heads was similar to that of fresh sperm. Although SEMG1 mRNA was not detected in any sample, PRM2 mRNA was detected in three samples. In the STR analysis, all loci were detected in the 33-years-old sample and five loci were detected in the 56-years-old sample. We confirmed that current forensic examinations - including STR analysis - could be applied to extremely aged seminal stains. These results could be useful for forensic practice.

Molecular analysis of testis biopsy and semen pellet as complementary methods with histopathological analysis of testis in non-obstructive azoospermia

PURPOSE

Non-obstructive azoospermia (NOA) is one the many causes of male infertility (10 %) resulting from testicular failure. Multiple testicular biopsies fail to find mature sperm in at least 50 % of cases Therefore; hunting for sensitive and specific biomarkers of spermatogenesis that could better determine the fertility status in NOA can lead to improved management of male infertility. Therefore, we evaluated sperm production through analyses of germ cell-specific transcripts (DAZ, TSPY1, SPTRX3 and SPTRX1) in semen and testicular biopsies of men with azoospermia.

METHODS

We collected semen (N=83) and testis biopsies (N=31) from men with non-obstructive azoospermia. We later extracted RNA and synthesized cDNA using washed semen precipitate and testicular tissues. We also performed semi-nested PCR with designed specific primers. Using H&E method, an expert pathologist performed the histopathological evaluation. Having categorized the patients into three groups based on histopathological results, we calculated the agreement between molecular results of semen and tissues with histopathological findings for each patient using Kappa statistical test.

RESULTS

Molecular findings of precipitated semen and testicular tissues were in disagreement with histopathological results in most cases. Molecular analysis of testis biopsies showed significant difference (Kappa coefficient=0.009, P value=0.894) with histopathological results; TSPY1, DAZ, SPTRX3 and SPTRX1 were respectively detected in 94 %, 94 %, 17.6 % and 52.9 % of men diagnosed with germ cell aplasia.

CONCLUSIONS

Molecular analysis of semen does not provide sufficient sensitivity and specificity to be used as a screening test at the present time, but it is a useful adjunct to histopathological methods in men with NOA. Spermatid/sperm specific transcripts indicated the possibility to find mature sperm following repeated multiple testicular sperm extraction (TESE) or microdisection TESE (mTESE).

Recovery of cell-free mRNA and microRNA from human semen based on their physical nature

Cell-free seminal mRNA (cfs-mRNA) and microRNA (cfs-miRNA) have been found in human ejaculate and reported as promising noninvasive biomarkers for disorders of male reproductive organs and forensic identification. However, seminal plasma is particularly challenging for RNA extraction due to its complicated composition and high content of protein, DNA, and polysaccharide. Here, we report a novel, simple, and reliable method for the isolation of cfs-mRNA and cfs-miRNA from human semen based on our previous findings of their physical nature. Seminal microvesicles (0.1-0.5 µm in diameter), which contain the majority of cfs-mRNA, were enriched by a microfilter. Protein complexes, which most cfs-miRNA is bound with, were enriched by an ultrafilter. Harvesting the complexes or microvesicles, in which RNAs exist, avoided the influence of other components in human semen, thus favoring RNA isolation and purification. This new method can efficiently isolate cfs-mRNA and cfs-miRNA separately based on their physical nature, with high RNA purity, and low DNA contamination. It may also be applied or modified to isolate cell-free RNAs in other fluids.

Expression analysis of MND1/GAJ, SPATA22, GAPDHS and ACR genes in testicular biopsies from non-obstructive azoospermia (NOA) patients

BACKGROUND

High-throughput studies provide a wide spectrum of genes for use as predictive markers during testicular sperm extraction (TESE) in combination with ICSI. In this work, we used the specimens from testicular biopsies of men with non-obstructive azoospermia who underwent TESE to investigate the expression of spermatogenesis-related genes MND1, SPATA22, GAPDHS and ACR.

METHODS

Testicular biopsy specimens were subdivided into three groups: hypospermatogenesis (HS); maturation arrest (MA); and Sertoli cell-only syndrome (SCO). The levels of expression of the spermatogenesis-related genes MND1, SPATA22, GAPDHS and ACR in the testes were compared among these three groups using the reverse transcription polymerase chain reaction (RT-PCR) technique.

RESULTS

Analysis of the expression of spermatogenic genes in human testes with abnormal spermatogenesis showed different expression patterns in patients from different groups. Fertilization rate for studied set of patients was 66% and pregnancy rate 29%. For HS group fertilization rate was 72% and pregnancy rate 32%, while for MA group fertilization and pregnancy rates were 54% and 26%, respectively. Fertilization rates in relation to the studied genes were uniformly around 70%, pregnancy rates for ACR and GAPDHS genes were surprisingly low at 6% and 8% correspondingly.

CONCLUSIONS

Analysis of the expression of genes involved in spermatogenesis can be a fast additional test for the level of spermatogenesis in testicular samples.

Genome-wide promoter methylation profile of human testis and epididymis: identified from cell-free seminal DNA

Background

DNA methylation analysis is useful for investigation of male fertility in mammals, whereas the reliance on tissues limits the research on human. We have previously found the presence of high concentration of cell-free seminal DNA (cfsDNA) in human semen. We proposed that some testis and epididymis-specific methylated promoters could be detected in human cfsDNA, and thus hold promise as noninvasive epigenetic biomarkers for male infertility, of which most cases are caused by defects in testicular sperm production or epididymal sperm maturation.

Results

The ejaculate of successfully vasectomized men does not contain any secretion from testis and epididymis. Here we compared genome-wide promoter methylation profiles in cfsDNA between health donors and post-vasectomy men. Promoters of 367 testis and epididymis-specific hypomethylated genes and 134 hypermethylated genes were identified. Subsequent validation by Methyl-DNA immunoprecipitation and MethyLight analysis confirmed the result of promoter microarray. Gene Ontology analysis revealed many genes involved in male reproduction.

Conclusion

We detected the testis and epididymis-specific methylated promoters in human cfsDNA, which may be used for noninvasive epigenetic biomarkers for the study and diagnosis of male infertility.

Biotechnological approaches to the treatment of aspermatogenic men

Aspermatogenesis is a severe impairment of spermatogenesis in which germ cells are completely lacking or present in an immature form, which results in sterility in approximately 25% of patients. Because assisted reproduction techniques require mature germ cells, biotechnology is a valuable tool for rescuing fertility while maintaining biological fatherhood. However, this process involves, for instance, the differentiation of preexisting immature germ cells or the production/derivation of sperm from somatic cells. This review critically addresses four potential techniques: sperm derivation in vitro, germ stem cell transplantation, xenologous systems, and haploidization. Sperm derivation in vitro is already feasible in fish and mammals through organ culture or 3D systems, and it is very useful in conditions of germ cell arrest or in type II Sertoli-cell-only syndrome. Patients afflicted by type I Sertoli-cell-only syndrome could also benefit from gamete derivation from induced pluripotent stem cells of somatic origin, and human haploid-like cells have already been obtained by using this novel methodology. In the absence of alternative strategies to generate sperm in vitro, in germ cells transplantation fertility is restored by placing donor cells in the recipient germ-cell-free seminiferous epithelium, which has proven effective in conditions of spermatogonial arrest. Grafting also provides an approach for ex-vivo generation of mature sperm, particularly using prepubertal testis tissue. Although less feasible, haploidization is an option for creating gametes based on biological cloning technology. In conclusion, the aforementioned promising techniques remain largely experimental and still require extensive research, which should address, among other concerns, ethical and biosafety issues, such as gamete epigenetic status, ploidy, and chromatin integrity.