Cellular Therapy via Spermatogonial Stem Cells for Treating Impaired Spermatogenesis, Non-Obstructive Azoospermia

Cyto- and Histopographic Assessment of CPA3-Positive Testicular Mast Cells in Obstructive and Non-Obstructive Azoospermia

Infertility is an important personal and society disease, of which the male factor represents half of all causes. One of the aspects less studied in male infertility is the immunological testicular microenvironment. Mast cells (MCs), having high potential for regulating spermatogenesis due to fine-tuning the state of the integrative buffer metabolic environment, are one of the most crucial cellular subpopulations of the testicular interstitium. One important component of the MC secretome is proteases that can act as proinflammatory agents and in extracellular matrix (ECM) remodeling. In the testis, MCs are an important cell component of the testicular interstitial tissue (TIT). However, there are still no studies addressing the analysis of a specific MC protease-carboxypeptidase A3 (CPA3)-in cases with altered spermatogenesis. The cytological and histotopographic features of testicular CPA3+ MCs were examined in a study involving 34 men with azoospermia. As revealed, in cases with non-obstructive azoospermia, a higher content of CPA3+ MCs in the TIT and migration to the microvasculature and peritubular tissue of seminiferous tubules were observed when compared with cases with obstructive azoospermia. Additionally, a high frequency of CPA3+ MCs colocalization with fibroblasts, Leydig cells, and elastic fibers was detected in cases with NOA. Thus, CPA3 seems to be of crucial pathogenetic significance in the formation of a profibrogenic background of the tissue microenvironment, which may have direct and indirect effects on spermatogenesis.

USP11 regulates proliferation and apoptosis of human spermatogonial stem cells via HOXC5-mediated canonical WNT/β-catenin signaling pathway

Spermatogonial stem cells (SSCs) are capable of transmitting genetic information to the next generations and they are the initial cells for spermatogenesis. Nevertheless, it remains largely unknown about key genes and signaling pathways that regulate fate determinations of human SSCs and male infertility. In this study, we explored the expression, function, and mechanism of USP11 in controlling the proliferation and apoptosis of human SSCs as well as the association between its abnormality and azoospermia. We found that USP11 was predominantly expressed in human SSCs as shown by database analysis and immunohistochemistry. USP11 silencing led to decreases in proliferation and DNA synthesis and an enhancement in apoptosis of human SSCs. RNA-sequencing identified HOXC5 as a target of USP11 in human SSCs. Double immunofluorescence, Co-immunoprecipitation (Co-IP), and molecular docking demonstrated an interaction between USP11 and HOXC5 in human SSCs. HOXC5 knockdown suppressed the growth of human SSCs and increased apoptosis via the classical WNT/β-catenin pathway. In contrast, HOXC5 overexpression reversed the effect of proliferation and apoptosis induced by USP11 silencing. Significantly, lower levels of USP11 expression were observed in the testicular tissues of patients with spermatogenic disorders. Collectively, these results implicate that USP11 regulates the fate decisions of human SSCs through the HOXC5/WNT/β-catenin pathway. This study thus provides novel insights into understanding molecular mechanisms underlying human spermatogenesis and the etiology of azoospermia and it offers new targets for gene therapy of male infertility.

Isolation and In Vitro Propagation of Human Spermatogonial Stem Cells (SSCs)

Preservation of human spermatogonial stem cells (SSCs) may be suitable for young male patients at risk of male infertility due to various causes, such as gonadotoxic treatment or genetic diseases. With optimal cryopreservation, cell viability can be retained to reestablish spermatogenesis in the future through autologous transplantation or in vitro differentiation of SSCs. This protocol outlines techniques to optimize the SSCs isolation and in vitro culture. With particular emphasis on the microscopic characteristics encountered, this protocol outlines a broader approach to processing tissues with varying morphologies among patients.

Polymorphisms and expression levels of TNP2, SYCP3, and AZFa genes in patients with azoospermia

OBJECTIVE

Azoospermia (the total absence of sperm in the ejaculate) affects approximately 10% of infertile males. Despite diagnostic advances, azoospermia remains the most challenging issue associated with infertility treatment. Our study evaluated transition nuclear protein 2 (TNP2) and synaptonemal complex protein 3 (SYCP3) polymorphisms, azoospermia factor a (AZFa) microdeletion, and gene expression levels in 100 patients with azoospermia.

METHODS

We investigated a TNP2 single-nucleotide polymorphism through polymerase chain reaction (PCR) restriction fragment length polymorphism analysis using a particular endonuclease. An allele-specific PCR assay for SYCP3 was performed utilizing two forward primers and a common reverse primer in two PCR reactions. Based on the European Academy of Andrology guidelines, AZFa microdeletions were evaluated by multiplex PCR. TNP2, SYCP3, and the AZFa region main gene (DEAD-box helicase 3 and Y-linked [DDX3Y]) expression levels were assessed via quantitative PCR, and receiver operating characteristic curve analysis was used to determine the diagnostic capability of these genes.

RESULTS

The TNP2 genotyping and allelic frequency in infertile males did not differ significantly from fertile volunteers. In participants with azoospermia, the allelic frequency of the SYCP3 mutant allele (C allele) was significantly altered. Deletion of sY84 and sY86 was discovered in patients with azoospermia and oligozoospermia. Moreover, SYCP3 and DDX3Y showed decreased expression levels in the azoospermia group, and they exhibited potential as biomarkers for diagnosing azoospermia (area under the curve, 0.722 and 0.720, respectively).

CONCLUSION

These results suggest that reduced SYCP3 and DDX3Y mRNA expression profiles in testicular tissue are associated with a higher likelihood of retrieving spermatozoa in individuals with azoospermia. The homozygous genotype TT of the SYCP3 polymorphism was significantly associated with azoospermia.

Effects of clinical medications on male fertility and prospects for stem cell therapy

An increasing number of men require long-term drug therapy for various diseases. However, the effects of long-term drug therapy on male fertility are often not well evaluated in clinical practice. Meanwhile, the development of stem cell therapy and exosomes treatment methods may provide a new sight on treating male infertility. This article reviews the influence and mechanism of small molecule medications on male fertility, as well as progress of stem cell and exosomes therapy for male infertility with the purpose on providing suggestions (recommendations) for evaluating the effect of drugs on male fertility (both positive and negative effect on male fertility) in clinical application and providing strategies for diagnosis and treatment of male infertility.

Oxidative stress-induced apoptosis and autophagy: Balancing the contrary forces in spermatogenesis

Spermatogenesis is a complex process in the testis and is a cornerstone of male infertility. The abundance of unsaturated fatty acid and high cell division rate make male germs cells prone to DNA deterioration. ROS-mediated oxidative stress triggers DNA damage, autophagy, and apoptosis in male germ cells, which are critical causative factors that lead to male infertility. The complex connection and molecular crosstalk between apoptosis and autophagy is seen at multifaceted levels that interconnect the signaling pathways of these two processes. Multilevel interaction between apoptosis and autophagy is a seamless state of survival and death in response to various stressors. Interaction between multiple genes and proteins such as the mTor signaling pathway, Atg12 proteins, and the death adapter proteins, such as Beclin 1, p53, and Bcl-2 family proteins, validates such a link between these two phenomena. Testicular cells being epigenetically different from somatic cells, undergo numerous significant epigenetic transitions, and ROS modulates the epigenetic framework of mature sperm. Epigenetic deregulation of apoptosis and autophagy under oxidative stress conditions can cause sperm cell damage. The current review recapitulates the current role of prevailing stressors that generate oxidative stress leading to the induction of apoptosis and autophagy in the male reproductive system. Considering the pathophysiological consequences of ROS-mediated apoptosis and autophagy, a combinatorial approach, including apoptosis inhibition and autophagy activation, a therapeutic strategy to treat male idiopathic infertility. Understanding the crosslink between apoptosis and autophagy under stress conditions in male germ cells may play an essential role in developing therapeutic strategies to treat infertility.

Integrated bioinformatics analysis of the transcription factor-mediated gene regulatory networks in the formation of spermatogonial stem cells

Background: In vitro induction of spermatogonial stem cells (SSCs) from embryonic stem cells (ESCs) provides a promising tool for the treatment of male infertility. A variety of molecules are involved in this complex process, which needs to be further clarified. Undoubtedly, the increased knowledge of SSC formation will be beneficial to facilitate the currently complex induction process. Methods: Based on ATAC-seq, DNase-seq, RNA-seq, and microarray data from GEO datasets, chromatin property data (ATAC-seq, DNase-seq) and gene expression data (RNA-seq, microarray data) were combined to search for SSC-specific transcription factors (TFs) and hub SSC-specific genes by using the WGCNA method. Then, we applied RNA-seq and microarray data screening for key SSC-specific TFs and constructed key SSC-specific TF-mediated gene regulatory networks (GRNs) using ChIP-seq data. Results: First, after analysis of the ATAC-seq and DNase-seq data of mouse ESCs, primordial germ cells (PGCs), and SSCs, 33 SSC-specific TFs and 958 targeting genes were obtained. RNA-seq and WGCNA revealed that the key modules (turquoise and red) were the most significantly related to 958 SSC-specific genes, and a total of 10 hub SSC-specific genes were identified. Next, when compared with the cell-specific TFs in human ESCs, PGCs, and SSCs, we obtained five overlapping SSC-specific TF motifs, including the NF1 family TF motifs (NFIA, NFIB, NFIC, and NFIX), GRE, Fox:Ebox, PGR, and ARE. Among these, Nfib and Nfix exhibited abnormally high expression levels relative to mouse ESCs and PGCs. Moreover, Nfib and Nfix were upregulated in the testis sample with impaired spermatogenesis when compared with the normal group. Finally, the ChIP-seq data results showed that NFIB most likely targeted the hub SSC-specific genes of the turquoise module (Rpl36al, Rps27, Rps21, Nedd8, and Sec61b) and the red module (Vcam1 and Ccl2). Conclusion: Our findings preliminarily revealed cell-specific TFs and cell-specific TF-mediated GRNs in the process of SSC formation. The hub SSC-specific genes and the key SSC-specific TFs were identified and suggested complex network regulation, which may play key roles in optimizing the induction efficiency of the differentiation of ESCs into SSCs in vitro.

Microarray and in silico analysis of DNA repair genes between human testis of patients with nonobstructive azoospermia and normal cells

DNA repair processes are critical to maintaining genomic integrity. As a result, dysregulation of repair genes is likely to be linked with health implications, such as an increased prevalence of infertility and an accelerated rate of aging. We evaluated all the DNA repair genes (322 genes) by microarray. This study has provided insight into the connection between DNA repair genes, including RAD23B, OBFC2A, PMS1, UBE2V1, ERCC5, SMUG1, RFC4, PMS2L5, MMS19, SHFM1, INO80, PMS2L1, CHEK2, TRIP13, and POLD4. The microarray analysis of six human cases with different nonobstructive azoospermia revealed that RAD23B, OBFC2A, PMS1, UBE2V1, ERCC5, SMUG1, RFC4, PMS2L5, MMS19, SHFM1, and INO80 were upregulated, and expression of PMS2L1, CHEK2, TRIP13, and POLD4 was downregulated versus the normal case. For this purpose, Enrich Shiny GO, STRING, and Cytoscape online evaluation was applied to predict proteins' functional and molecular interactions and then performed to recognize the master pathways. Functional enrichment analysis revealed that the biological process (BP) terms "base-excision repair, AP site formation," "nucleotide-excision repair, DNA gap filling," and "nucleotide-excision repair, preincision complex assembly" was significantly overexpressed in upregulated differentially expressed genes (DEGs). BP analysis of downregulated DEGs highlighted "histone phosphorylation," "DNA damage response, detection DNA response," "mitotic cell cycle checkpoint signaling," and "double-strand break repair." Overrepresented molecular function (MF) terms in upregulated DEGs included "Oxidized base lesion DNA N-glycosylase activity," "uracil DNA N-glycosylase activity," "bubble DNA binding" and "DNA clamp loader activity." Interestingly, MF investigation of downregulated DEGs showed overexpression in "heterotrimeric G-protein complex," "5'-deoxyribose-5-phosphate lyase activity," "minor groove of adenine-thymine-rich DNA binding," and "histone kinase activity." Our findings suggest that these genes and their interacting hub proteins could help determine the pathophysiology of germ cell abnormalities and infertility.

Germline stem cells in human

The germline cells are essential for the propagation of human beings, thus essential for the survival of mankind. The germline stem cells, as a unique cell type, generate various states of germ stem cells and then differentiate into specialized cells, spermatozoa and ova, for producing offspring, while self-renew to generate more stem cells. Abnormal development of germline stem cells often causes severe diseases in humans, including infertility and cancer. Primordial germ cells (PGCs) first emerge during early embryonic development, migrate into the gentile ridge, and then join in the formation of gonads. In males, they differentiate into spermatogonial stem cells, which give rise to spermatozoa via meiosis from the onset of puberty, while in females, the female germline stem cells (FGSCs) retain stemness in the ovary and initiate meiosis to generate oocytes. Primordial germ cell-like cells (PGCLCs) can be induced in vitro from embryonic stem cells or induced pluripotent stem cells. In this review, we focus on current advances in these embryonic and adult germline stem cells, and the induced PGCLCs in humans, provide an overview of molecular mechanisms underlying the development and differentiation of the germline stem cells and outline their physiological functions, pathological implications, and clinical applications.

The Role of Stem Cells and Their Derived Extracellular Vesicles in Restoring Female and Male Fertility

Infertility is a globally recognized issue caused by different reproductive disorders. To date, various therapeutic approaches to restore fertility have been attempted including etiology-specific medication, hormonal therapies, surgical excisions, and assisted reproductive technologies. Although these approaches produce results, however, fertility restoration is not achieved in all cases. Advances in using stem cell (SC) therapy hold a great promise for treating infertile patients due to their abilities to self-renew, differentiate, and produce different paracrine factors to regenerate the damaged or injured cells and replenish the affected germ cells. Furthermore, SCs secrete extracellular vesicles (EVs) containing biologically active molecules including nucleic acids, lipids, and proteins. EVs are involved in various physiological and pathological processes and show promising non-cellular therapeutic uses to combat infertility. Several studies have indicated that SCs and/or their derived EVs transplantation plays a crucial role in the regeneration of different segments of the reproductive system, oocyte production, and initiation of sperm production. However, available evidence triggers the need to testify the efficacy of SC transplantation or EVs injection in resolving the infertility issues of the human population. In this review, we highlight the recent literature covering the issues of infertility in females and males, with a special focus on the possible treatments by stem cells or their derived EVs.