Conserved and non-conserved characteristics of porcine glial cell line-derived neurotrophic factor expressed in the testis

Synergistic effects of glial cell line-derived neurotrophic factor and base-medium on in vitro culture of testicular tissue derived from prepubertal collared peccary

We evaluated the influence of different media plus various concentrations of Glial cell line-derived neurotrophic factor (GDNF) during the in vitro culture (IVC) of testicular tissues from prepubertal collared peccary. Testes from 5 individuals were collected, fragmented and cultured for 28 days (34°C and 5% CO2). Culture media were Dulbecco's modified essential medium (DMEM) or stem cell serum free media (StemPro-34™ SFM), both supplemented with various concentrations of GDNF (0, 10, or 20 ng/mL). Fragments were cultured on the flat surface of 0.75% agarose gel and were evaluated every 7 days for fragment area, histomorphology, cellular viability, and proliferative activity. Data were expressed as mean ± standard error and analyzed by Kruskal-Wallis's and Tukey test. Fragments area decreased over the 28 days-culture, regardless of the treatment. For morphology, the StemPro-37 SFM medium plus 10 ng/mL GDNF provided higher scores at all time points in comparison to DMEM using any GDNF concentration (p < .05). After 28 days, similar cellular viability (~70%) was observed in all treatments (p > .05). For proliferating cell nuclear antigen assay, only DMEM plus 10 ng/mL GDNF improved (p < .05) cellular proliferation on Days 14 and 28. Looking at argyrophilic nucleolar organizing regions, after 28 days, there were no differences among treatments regarding cell proliferative capacity for both spermatogonia and Sertoli cells (p > .05). In summary, the DMEM and StemPro-34 SFM are adequate medium for IVC of prepubertal peccary testicular tissue. Supplementation with GDNF, especially at a 10 ng/mL concentration, appears to be essential for the maintenance of cell survival and proliferation.

Gdnf Acts as a Germ Cell-Derived Growth Factor and Regulates the Zebrafish Germ Stem Cell Niche in Autocrine- and Paracrine-Dependent Manners

Glial cell line-derived neurotrophic factor (GDNF) and its receptor (GDNF Family Receptor α1-GFRα1) are well known to mediate spermatogonial stem cell (SSC) proliferation and survival in mammalian testes. In nonmammalian species, Gdnf and Gfrα1 orthologs have been found but their functions remain poorly investigated in the testes. Considering this background, this study aimed to understand the roles of the Gdnf-Gfrα1 signaling pathway in zebrafish testes by combining in vivo, in silico and ex vivo approaches. Our analysis showed that zebrafish exhibit two paralogs for Gndf (gdnfa and gdnfb) and its receptor, Gfrα1 (gfrα1a and gfrα1b), in accordance with a teleost-specific third round of whole genome duplication. Expression analysis further revealed that both ligands and receptors were expressed in zebrafish adult testes. Subsequently, we demonstrated that gdnfa is expressed in the germ cells, while Gfrα1a/Gfrα1b was detected in early spermatogonia (mainly in types A_und and A_diff) and Sertoli cells. Functional ex vivo analysis showed that Gdnf promoted the creation of new available niches by stimulating the proliferation of both type A_und spermatogonia and their surrounding Sertoli cells but without changing pou5f3 mRNA levels. Strikingly, Gdnf also inhibited late spermatogonial differentiation, as shown by the decrease in type B spermatogonia and down-regulation of dazl in a co-treatment with Fsh. Altogether, our data revealed that a germ cell-derived factor is involved in maintaining germ cell stemness through the creation of new available niches, supporting the development of spermatogonial cysts and inhibiting late spermatogonial differentiation in autocrine- and paracrine-dependent manners.

SETDB1 Regulates Porcine Spermatogonial Adhesion and Proliferation through Modulating MMP3/10 Transcription

The transition from gonocytes into spermatogonia takes place during the homing process. A subpopulation of undifferentiated spermatogonia in niche then shifts to spermatogonial stem cells (SSCs), accompanied by the self-renewal ability to maintain life-long fertility in males. Enormous changes in cell morphology, gene expression, and epigenetic features have been reported during spermatogenesis. However, little is known about the difference of these features in SSCs during aging. Here, we examined the dynamics of SET domain bifurcated 1 (SETDB1) expression in porcine testes. SETDB1 was expressed in postnatal undifferentiated spermatogonia, while gradually disappeared after being packed within the basal compartment of seminiferous tubules. In addition, the cell-adhesion ability, proliferative activity, and trimethylation of the histone H3 lysine 9 (H3K9me3) level were significantly altered in SETDB1-deficient porcine SSCs. Moreover, the matrix metalloproteinases 3/10 (MMP3/10) was upregulated at both mRNA and protein levels. These results illustrate the significance of SETDB1 in modulating early male germ cell development.

Recent advances: fertility preservation and fertility restoration options for males and females

Fertility preservation is the process of saving gametes, embryos, gonadal tissues and/or gonadal cells for individuals who are at risk of infertility due to disease, medical treatments, age, genetics, or other circumstances. Adult patients have the options to preserve eggs, sperm, or embryos that can be used in the future to produce biologically related offspring with assisted reproductive technologies. These options are not available to all adults or to children who are not yet producing mature eggs or sperm. Gonadal cells/tissues have been frozen for several thousands of those patients worldwide with anticipation that new reproductive technologies will be available in the future. Therefore, the fertility preservation medical and research communities are obligated to responsibly develop next-generation reproductive technologies and translate them into clinical practice. We briefly describe standard options to preserve and restore fertility, but the emphasis of this review is on experimental options, including an assessment of readiness for translation to the human fertility clinic.

Can nanomaterials induce reproductive toxicity in male mammals? A historical and critical review

The nanotechnology enabled the development of nanomaterials (NMs) with a variety of industrial, biomedical, and consumer applications. However, the mechanism of action (MoA) and toxicity of NMs remain unclear, especially in the male reproductive system. Thus, this study aimed to perform a bibliometric and systematic review of the literature on the toxic effects of different types of NMs on the male reproductive system and function in mammalian models. A series of 236 articles related to the in vitro and in vivo reproductive toxicity of NMs in mammalian models were analyzed. The data concerning the bioaccumulation, experimental conditions (types of NMs, species, cell lines, exposure period, and routes of exposure), and the MoA and toxicity of NMs were summarized and discussed. Results showed that this field of research began in 2005 and has experienced an exponential increase since 2012. Revised data confirmed that the NMs have the ability to cross the blood-testis barrier and bioaccumulate in several organs of the male reproductive system, such as testis, prostate, epididymis, and seminal vesicle. A similar MoA and toxicity were observed after in vitro and in vivo exposure to NMs. The NM reproductive toxicity was mainly related to ROS production, oxidative stress, DNA damage and apoptosis. In conclusion, the NM exposure induces bioaccumulation and toxic effects on male reproductive system of mammal models, confirming its potential risk to human and environmental health. The knowledge concerning the NM reproductive toxicity contributes to safety and sustainable use of nanotechnology.

Long-Term Ex Vivo Expansion of Murine Spermatogonial Stem Cells in a Simple Serum-Free Medium

Spermatogonial stem cells (SSCs) possess both self-renewal and differentiation abilities to sustain lifelong production of enormous numbers of spermatozoa in males. SSCs hold a unique position among tissue-specific stem cells in adults because of their ability to transmit the genetic information to subsequent generations. Ex vivo expansion of SSCs in conjunction with their transplantation is highly invaluable to study SSCs and develop new reproductive technologies for therapeutic applications. In this chapter, we describe a culture system involving a simple serum-free medium for mouse SSCs. Elimination of the serum from the culture is important to enhance the effects of exogenous factors, which are rather masked by the serum, and to avert the serum-induced inflammatory responses of testicular mesenchymal cells, which cause adverse effects on SSC proliferation. Consequently, using this culture system has proven for the first time that glial cell line-derived neurotrophic factor (GDNF) was found to be the key factor to drive the self-renewing proliferation of SSCs, and fibroblast growth factor 2 enhanced the GDNF-dependent proliferation of SSCs. Besides determining these two key cytokines, the simplicity of the system enabled individual modification of its components to develop long-term cultures of rat and rabbit SSCs. The basics of these culture systems will enable development of the culture conditions for human and other mammalian SSCs in the near future.

Metabolic Requirements for Spermatogonial Stem Cell Establishment and Maintenance In Vivo and In Vitro

The spermatogonial stem cell (SSC) is a unique adult stem cell that requires tight physiological regulation during development and adulthood. As the foundation of spermatogenesis, SSCs are a potential tool for the treatment of infertility. Understanding the factors that are necessary for lifelong maintenance of a SSC pool in vivo is essential for successful in vitro expansion and safe downstream clinical usage. This review focused on the current knowledge of prepubertal testicular development and germ cell metabolism in different species, and implications for translational medicine. The significance of metabolism for cell biology, stem cell integrity, and fate decisions is discussed in general and in the context of SSC in vivo maintenance, differentiation, and in vitro expansion.

In Vitro and In Vivo Determinations of The Anti-GDNF Family Receptor Alpha 1 Antibody in Mice by Immunochemistry and RT-PCR

Background

The glial cell-derived neurotrophic factor (GDNF) family plays essential roles in the maintenance, growth, regulatory and signalling pathways of spermatogonial stem cells (SSCs). In this study, we analysed the expression of anti-GDNF family receptor alpha 1 antibody (GFRa1) by immunohistochemistry (IHC), immunocytochemistry (ICC), Fluidigm real-time polymerase chain reaction (RT-PCR) and flow cytometry analyses.

Materials and Methods

In this experiment study, ICC, IHC, Fluidigm RT-PCR and flow cytometry were used to analyse the expression of the germ cell marker GFRa1 in testis tissue and SSC culture.

Results

IHC analysis showed that there were two groups of GFRa1 positive cells in the seminiferous tubules based on their location and expression shape - a small round punctuated shape on the basal compartment donut shape and a C-shaped expression located between the basal and the luminal compartments of the seminiferous tubules. OCT4 and PLZF positive cells may have similar patterns of expression as the first group. Assessment of the seminiferous tubule sections demonstrated that about 27% of the SSCs were positive for GFRa1. Fluidigm RT-PCR confirmed the significant expression (P<0.001) of GFRa1 in the SSCs compared to testicular stromal cells (TSCs). Flow cytometry analysis demonstrated that about 75% of the isolated SSCs colonies were positive for GFRa1.

Conclusion

The results indicated that GFRa1 had a specific expression pattern both in vivo and in vitro. This finding could be helpful for understanding the proliferation, maintenance and signalling pathways of SSCs, and differentiation of meiotic and haploid germ cells.

Scaffold protein Lin7 family in membrane skeletal protein complex in mouse seminiferous tubules

The membrane skeletal complex, protein 4.1G-membrane palmitoylated protein 6 (MPP6), is localized in spermatogonia and early spermatocytes of mouse seminiferous tubules. In this study, we investigated the Lin7 family of scaffolding proteins, which interact with MPP6. By immunohistochemistry, Lin7a and Lin7c were localized in germ cells, and Lin7c had especially strong staining in spermatogonia and early spermatocytes, characterized by staging of seminiferous tubules. By immunoelectron microscopy, Lin7 localization appeared under cell membranes in germ cells. The Lin7 staining pattern in seminiferous tubules was partially similar to that of 4.1G, cell adhesion molecule 1 (CADM1), and melanoma cell adhesion molecule (MCAM). Lin7-positive cells included type A spermatogonia, as revealed by double staining for Lin28a. Lin7 staining became weaker in MPP6-deficient mice by immunohistochemistry and western blotting, indicating that MPP6 transports and maintains Lin7 in germ cells. The histology of seminiferous tubules was unchanged in MPP6-deficient mice compared to that of wild-type mice. In cultured spermatogonial stem cells maintained with glial cell line-derived neurotropic factor (GDNF), Lin7 was clearly expressed and immunolocalized along cell membranes, especially at cell-cell junctions. Thus, Lin7 protein is expressed in germ cells, and Lin7, particularly Lin7c, is a useful marker for early spermatogenesis.