Exosomal microRNAs in seminal plasma are markers of the origin of azoospermia and can predict the presence of sperm in testicular tissue

Abstract

STUDY QUESTIONAre exosomal microRNAs (miRNAs) in seminal plasma (SP) useful as markers of the origin of azoospermia and the presence of sperm in the testis?SUMMARY ANSWEROur study demonstrated the potential of several miRNAs contained in small extracellular vesicles (sEVs) of seminal fluid as sensitive and specific biomarkers for selecting those azoospermic individuals with real chances of obtaining spermatozoa from the testicular biopsy.WHAT IS KNOWN ALREADYThere are no precise non-invasive diagnostic methods for classifying the origin of the sperm defects in semen and the spermatogenic reserve of the testis in those infertile men with a total absence of sperm in the ejaculate (azoospermia). The diagnosis of such individuals is often based on the practice of biopsies. In this context it is reasonable to study the presence of organ-specific markers in human semen that contains fluid from the testis and the male reproductive glands, which could help in the diagnosis and prognosis of male infertility. Additionally, seminal fluid contains high concentrations of sEVs that are morphologically and molecularly consistent with exosomes, which originate from multiple cellular sources in the male reproductive tract.STUDY DESIGN, SIZE, DURATIONA case and control prospective study was performed. This study compares the miRNA content of exosomes in semen samples obtained from nine normozoospermic fertile individuals (control group), 14 infertile men diagnosed with azoospermia due to spermatogenic failure, and 13 individuals with obstructive azoospermia and conserved spermatogenesis. Additionally, three severe oligozoospermic individuals (<5 × 106 sperm/ml) were included in the study.PARTICIPANTS/MATERIALS, SETTING, METHODSA differential high-throughput miRNA profiling analysis using miRNA quantitative PCR panels was performed in SP exosomes from azoospermic patients and fertile individuals.MAIN RESULTS AND THE ROLE OF CHANCEA total of 623 miRNAs were included in the miRNA profiling stage of the study. A total of 397 miRNAs (63.7%) were consistently detected in samples from all groups and statistically analysed, which revealed altered patterns of miRNA expression in infertile patients. We focused on the miRNAs that were differentially expressed between azoospermia as a result of an obstruction in the genital tract (i.e. having conserved spermatogenesis) and azoospermia caused by spermatogenic failure, and described, in a miRNA validation stage of the study, the expression values of one miRNA (miR-31-5p) in exosomes from semen as a predictive biomarker test for the origin of azoospermia with high sensitivity and specificity (>90%). The efficacy of the predictive test was even better when the blood FSH values were included in the analysis. Furthermore a model that included miR-539-5p and miR-941 expression values is also described as being useful for predicting the presence of residual spermatogenesis in individuals with severe spermatogenic disorders with diagnostic accuracy.LIMITATIONS, REASONS FOR CAUTIONFurther studi...

Expression of miRNA‐371a‐3p in seminal plasma and ejaculate is associated with sperm concentration

“…However, among the studies reported to date there is a wide variety of findings and so far neither one single microRNA nor any particular panel of microRNAs has evolved to be applicable for routine clinical diagnostics (Wu et al , ; Hu et al , ; Corral‐Vazquez et al , ; Barceló et al , ; Harchegani et al , ).…”

Seminal plasma miR‐210‐3p is a biomarker for screening dyszoospermia caused by varicocele

“…In previous studies, the stability of seminal plasma miRNAs as a biomarker has been widely discussed (Barcelo, Mata, Bassas, & Larriba, ; Wang et al, ; Wu et al, ; Zhi et al, ). Wang et al evaluated the stability of miRNAs (miR‐9, miR‐106b and miR‐202) expression by repeated freezing and thawing of seminal plasma and incubation at room temperature and 4°C for different durations.…”

“…Zhi et al found that the expression level of seminal plasma miR‐192a in patients who successfully ejaculated after varicocele repair was significantly higher than that in patients who failed. In another recent study, Barcelo et al () used differential high‐throughput miRNA profiling techniques for miRNA quantitative PCR plates to analyse differences in seminal plasma exosomes in azoospermia and fertile individuals. Their findings have revealed altered miRNAs in seminal plasma exosomes that may be involved in the process of azoospermia origin and testicular spermatogenesis.…”

MicroRNA signature in spermatozoa and seminal plasma of proven fertile men and in testicular tissue of men with obstructive azoospermia

“…Among the miRNAs detected in seminal plasma, five miRNAs (miR‐629‐3p, miR‐200b‐3p, miR‐425‐3p, miR‐33b‐3p and miR‐141‐3p) were previously described as being among the most stably expressed miRNAs in seminal plasma‐derived exosomes (Barcelo, Mata, Bassas, & Larriba, ). MiR‐141‐3p was reported to be stable in seminal plasma (Wu et al, ).…”