Pluripotency factor NANOG promotes germ cell maintenance in vitro without triggering dedifferentiation of spermatogonial stem cells

Expression and localization of Cyclin D1/Nanog and NF-κB/Bax protein in dysplastic testicles of mice

Testicular dysplasia significantly impairs male reproductive capacity. This study investigated the expression of Cyclin D1/Nanog and NF-κB/Bax in dysplastic testes of mice using histological staining, Western blotting, and immunohistochemistry. The results showed that Nanog and Bax expression were significantly higher in dysplastic testicular tissue than in normal tissue (P < 0.01). Cyclin D1 protein expression was higher in normal testis tissue than in dysplastic testis (P < 0.01). NF-κB was highly expressed in cryptorchid and normal testis with no significant difference (P > 0.05). Immunolocalization revealed that Nanog, NF-κB, and Bax were expressed in the cytoplasm of Leydig and spermatogenic cells. Cyclin D1 primarily expressed in the nucleus of Sertoli cells. These findings suggest that altered expression of Nanog, Cyclin D1, and Bax may contribute to testicular dysplasia. This study provides a scientific foundation for detecting testicular dysplasia and selecting appropriate animal models, ultimately informing strategies to improve male reproductive health.

Unraveling the Significance of Nanog in the Generation of Embryonic Stem-like Cells from Spermatogonia Stem Cells: A Combined In Silico Analysis and In Vitro Experimental Approach

Embryonic stem-like cells (ES-like cells) are promising for medical research and clinical applications. Traditional methods involve "Yamanaka" transcription (OSKM) to derive these cells from somatic cells in vitro. Recently, a novel approach has emerged, obtaining ES-like cells from spermatogonia stem cells (SSCs) in a time-related process without adding artificial additives to cell cultures, like transcription factors or small molecules such as pten or p53 inhibitors. This study aims to investigate the role of the Nanog in the conversion of SSCs to pluripotent stem cells through both in silico analysis and in vitro experiments. We used bioinformatic methods and microarray data to find significant genes connected to this derivation path, to construct PPI networks, using enrichment analysis, and to construct miRNA-lncRNA networks, as well as in vitro experiments, immunostaining, and Fluidigm qPCR analysis to connect the dots of Nanog significance. We concluded that Nanog is one of the most crucial differentially expressed genes during SSC conversion, collaborating with critical regulators such as Sox2, Dazl, Pou5f1, Dnmt3, and Cdh1. This intricate protein network positions Nanog as a pivotal factor in pathway enrichment for generating ES-like cells, including Wnt signaling, focal adhesion, and PI3K-Akt-mTOR signaling. Nanog expression is presumed to play a vital role in deriving ES-like cells from SSCs in vitro. Finding its pivotal role in this path illuminates future research and clinical applications.

Reestablishment of spermatogenesis after more than 20 years of cryopreservation of rat spermatogonial stem cells reveals an important impact in differentiation capacity

Treatment of cancer in children is increasingly successful but leaves many prepubertal boys suffering from infertility or subfertility later in life. A current strategy to preserve fertility in these boys is to cryopreserve a testicular biopsy prior to treatment with the expectation of future technologies allowing for the reintroduction of stem cells and restoration of spermatogenesis. Spermatogonial stem cells (SSCs) form the basis of male reproduction, differentiating into all germ cell types, including mature spermatozoa and can regenerate spermatogenesis following transplantation into an infertile testis. Here, we demonstrate that rat SSCs frozen for more than 20 years can be transplanted into recipient mice and produce all differentiating germ cell types. However, compared with freshly isolated cells or those frozen for a short period of time, long-frozen cells do not colonize efficiently and showed reduced production of spermatids. Single-cell RNA sequencing revealed similar profiles of gene expression changes between short- and long-frozen cells as compared with fresh immediately after thawing. Conversely, following transplantation, long-frozen samples showed enhanced stem cell signaling in the undifferentiated spermatogonia compartment, consistent with self-renewal and a lack of differentiation. In addition, long-frozen samples showed fewer round spermatids with detectable protamine expression, suggesting a partial block of spermatogenesis after meiosis resulting in a lack of elongating spermatids. These findings strongly suggest that prolonged cryopreservation can impact the success of transplantation to produce spermatogenesis, which may not be revealed by analysis of the cells immediately after thawing. Our analysis uncovered persistent effects of long-term freezing not found in other cryopreservation studies that lacked functional regeneration of the tissue and this phenomenon must be accounted for any future therapeutic application.

This study shows that spermatogonial stem cells frozen for more than 20 years can repopulate the niche when transplanted into an infertile host, but with lower efficiency and displaying abnormal spermatogenesis compared to fresh or short-term frozen cells. Single-cell RNA sequencing reveals details of the dysregulated signaling.

Pou5f1 and Nanog Are Reliable Germ Cell-Specific Genes in Gonad of a Protogynous Hermaphroditic Fish, Orange-Spotted Grouper (Epinephelus coioides)

Pluripotency markers Pou5f1 and Nanog are core transcription factors regulating early embryonic development and maintaining the pluripotency and self-renewal of stem cells. Pou5f1 and Nanog also play important roles in germ cell development and gametogenesis. In this study, Pou5f1 (EcPou5f1) and Nanog (EcNanog) were cloned from orange-spotted grouper, Epinephelus coioides. The full-length cDNAs of EcPou5f1 and EcNanog were 2790 and 1820 bp, and encoded 475 and 432 amino acids, respectively. EcPou5f1 exhibited a specific expression in gonads, whereas EcNanog was expressed highly in gonads and weakly in some somatic tissues. In situ hybridization analyses showed that the mRNA signals of EcNanog and EcPou5f1 were exclusively restricted to germ cells in gonads. Likewise, immunohistofluorescence staining revealed that EcNanog protein was limited to germ cells. Moreover, both EcPou5f1 and EcNanog mRNAs were discovered to be co-localized with Vasa mRNA, a well-known germ cell maker, in male and female germ cells. These results implied that EcPou5f1 and EcNanog could be also regarded as reliable germ cell marker genes. Therefore, the findings of this study would pave the way for elucidating the mechanism whereby EcPou5f1 and EcNanog regulate germ cell development and gametogenesis in grouper fish, and even in other protogynous hermaphroditic species.

POU5F1 Protein and Gene Expression Analysis in Neonate and Adult Mouse Testicular Germ Cells by Immunohistochemistry and Immunocytochemistry

POU5F1 (POU class 5 homeobox 1) is a transcription factor that is critically involved in the self-renewal of undifferentiated embryonic stem cells. In this present study, we have developed our study to analyze the expression of the POU5F1 in the neonatal and adult mice testis section and isolated spermatogonial stem cells (SSCs). We also examine POU5F1 protein localization by three various kinds of antibodies. In this experimental research, to enhance our understanding of the POU5F1 expression levels, protein localization, and function in testicular germ cell, we used immunohistochemistry, immunocytochemistry, and Fluidigm real-time polymerase chain reaction (RT-PCR) analysis in the mouse testis section and neonatal and adult SSCs, and also we used protein-protein network analysis and gene enrichment analysis for genes involved in testicular development. Counting POU5F1-positive cells represented significantly higher expression (p < 0.05) of POU5F1 in the adult testis in comparison to the neonate. Finally, Fluidigm RT-PCR showed a significant expression (p < 0.05) level of germ cells gene POU5F1 in neonate SSCs (1-2 week) than 16-24 week SSCs. The illustrated results identify POU5F1 as a necessary transcription factor of testicular germ cells and can be supportive for the investigation of the development and differentiation of SSCs.

A comparison of the effects of fetal bovine serum and newborn calf serum on cell growth and maintenance of cryopreserved mouse spermatogonial stem cells

Serum is a common supplement that is widely used to protect various cells and tissues from cryopreservation because it provides the necessary active components for cell growth and maintenance. In this study, we compared the effects of newborn calf serum (NCS) and fetal bovine serum (FBS) on the cryopreservation of mouse spermatogonial stem cells (SSCs). The isolated SSCs were cryopreserved in two groups: freezing medium that contained 10% DMSO (dimethyl sulfoxide) and 10% FBS in DMEM (Dulbecco's Modified Eagle's Medium) (group 1) and freezing medium that contained 10% DMSO and 10% NCS in DMEM (group 2). Real-time PCR was performed for stemness gene expression. The SSCs' viability was performed by trypan blue. We observed that the SSCs had increased viability in the NCS-freeze/thaw group (87.82%) compared to the FBS-freeze/thaw group (79.83%), but this increase was not statistically significant (P < 0.105). Promyelocytic leukemia zinc finger (Plzf) and Lin28 gene expression levels in the NCS-frozen/thawed SSCs were not significantly different compared to the FBS-frozen/thawed SSCs; however, Nanog gene expression increased considerably, and Dazl gene expression decreased significantly. The results in this study demonstrated that the presence of NCS in a solution of cryopreserved SSCs increased their viability after freeze/thawing and might promote the proliferation of cultivated SSCs in vitro by increasing the relative expression of Nanog.