Identification of testis derived differentially expressed spermatogenic microRNAs in idiopathic hypospermatogenesis

Objectives Hypospermatogenesis (HS) is a common histopathological subtype of non-obstructive azoospermia (NOA), characterized by a decrease in the total number of germ cells within the seminiferous tubule. The diagnosis of HS is made by invasive procedures like testicular biopsy or fine needle aspiration (FNA). MicroRNAs (miRs) are biomolecules with emerging roles as diagnostic biomarkers for diseases. This study aimed to investigate the differential miR expression profile in idiopathic HS (iHS) to explore candidate spermatogenic miRs in human male infertility. Material and Methods In this observational study, patients reporting azoospermia due to spermatogenic failure were recruited prospectively. Genetic exclusion was performed using XY-fluorescent in-situ hybridization (XY-FISH) and Yq microdeletion. Testicular FNA samples were used for total ribonucleic ccid (RNA) isolation. Small RNA sequencing-based exploratory analysis was performed on 20 iHS patients and five normospermatogenesis (NS) patients. nCounter miRNA expression based validation was performed for four iHS and four NS patients. Results Analysis of miRs in testicular tissue showed differential expression patterns having 49 downregulated and 3 upregulated miRs between iHS and NS patients, with miR-379-5p, miR-449a, miR-181c, miR-34b-3p, and miR-122b-5p being notable candidate spermatogenic miRNAs. Pathways such as Phosphatidylinositol 3 Kinase-Protein Kinase B (PI3K-Akt) and mitogen-activated protein kinase (MAPK) signaling and molecular functions like apoptosis and cell differentiation were significantly enriched in iHS patients. This is the first study of its kind to investigate the differential expression of micro-ribonucleic acid (miRs) in a cohort of NOA patients exclusively of the HS subtype. Comparing the study results to previously published data revealed that dysregulated spermatogenic miRs are shared in HS and other NOA subtypes. The analysis of spermatogenic miRs according to each patient’s profile showed significant dysregulation in miR expression, linked to 40% of cases with idiopathic HS. Conclusion This study provides important insight into the potential of miRNA to be used as a biomarker for the diagnosis of iHS. Although the study is based on a relatively low sample size, it provides a proof of concept which can be validated in a larger cohort.