The emerging role of extracellular vesicles in the testis

Unlocking Genetic Mysteries during the Epic Sperm Journey toward Fertilization: Further Expanding Cre Mouse Lines

The spatiotemporal expression patterns of genes are crucial for maintaining normal physiological functions in animals. Conditional gene knockout using the cyclization recombination enzyme (Cre)/locus of crossover of P1 (Cre/LoxP) strategy has been extensively employed for functional assays at specific tissue or developmental stages. This approach aids in uncovering the associations between phenotypes and gene regulation while minimizing interference among distinct tissues. Various Cre-engineered mouse models have been utilized in the male reproductive system, including Dppa3-MERCre for primordial germ cells, Ddx4-Cre and Stra8-Cre for spermatogonia, Prm1-Cre and Acrv1-iCre for haploid spermatids, Cyp17a1-iCre for the Leydig cell, Sox9-Cre for the Sertoli cell, and Lcn5/8/9-Cre for differentiated segments of the epididymis. Notably, the specificity and functioning stage of Cre recombinases vary, and the efficiency of recombination driven by Cre depends on endogenous promoters with different sequences as well as the constructed Cre vectors, even when controlled by an identical promoter. Cre mouse models generated via traditional recombination or CRISPR/Cas9 also exhibit distinct knockout properties. This review focuses on Cre-engineered mouse models applied to the male reproductive system, including Cre-targeting strategies, mouse model screening, and practical challenges encountered, particularly with novel mouse strains over the past decade. It aims to provide valuable references for studies conducted on the male reproductive system.

Regulation of spermatogonial stem cell differentiation by Sertoli cells-derived exosomes through paracrine and autocrine signaling

In the orchestrated environment of the testicular niche, the equilibrium between self-renewal and differentiation of spermatogonial stem cells (SSCs) is meticulously maintained, ensuring a stable stem cell reserve and robust spermatogenesis. Within this milieu, extracellular vesicles, specifically exosomes, have emerged as critical conveyors of intercellular communication. Despite their recognized significance, the implications of testicular exosomes in modulating SSC fate remain incompletely characterized. Given the fundamental support and regulatory influence of Sertoli cells (SCs) on SSCs, we were compelled to explore the role of SC-derived exosomes (SC-EXOs) in the SSC-testicular niche. Our investigation hinged on the hypothesis that SC-EXOs, secreted by SCs from the testes of 5-day-old mice-a developmental juncture marking the onset of SSC differentiation-participate in the regulation of this process. We discovered that exposure to SC-EXOs resulted in an upsurge of PLZF, MVH, and STRA8 expression in SSC cultures, concomitant with a diminution of ID4 and GFRA1 levels. Intriguingly, obstructing exosomal communication in a SC-SSC coculture system with the exosome inhibitor GW4869 attenuated SSC differentiation, suggesting that SC-EXOs may modulate this process via paracrine signaling. Further scrutiny revealed the presence of miR-493-5p within SC-EXOs, which suppresses Gdnf mRNA in SCs to indirectly restrain SSC differentiation through the modulation of GDNF expression-an indication of autocrine regulation. Collectively, our findings illuminate the complex regulatory schema by which SC-EXOs affect SSC differentiation, offering novel perspectives and laying the groundwork for future preclinical and clinical investigations.

Castration reduces mortality and increases resilience in male mice: what is next?

This commentary concerns our recent report that prepubertal castration rescued the shorter lifespan of males, using the first mouse line that robustly shows the same shorter longevity with a similar age-variable mortality disadvantage as human males. This model provides a unique opportunity for research to uncover the basis for this clinically important sex difference in aging. Researchers can now identify the hormones involved, the duration of exposure required, and, most important, the cellular and molecular targets, with the ultimate goal of developing therapeutic interventions to enhance health and reduce mortality without castration-compromising reproductive function.

Fertility Protection, A Novel Concept: Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Protect against Chemotherapy-Induced Testicular Cytotoxicity

Currently, there is no viable option for fertility preservation in prepubertal boys. Experimentally, controlled vitrification of testicular tissue has been evaluated and found to cause potential structural damage to the spermatogonial stem cell (SSC) niche during cryopreservation. In this report, we leveraged the regenerative effect of human umbilical cord-derived Mesenchymal stem cell exosomes (h-UCMSC-Exo) to protect against testicular damage from the cytotoxic effects of polychemotherapy (CTX). A chemotherapy-induced testicular dysfunctional model was established by CTX treatment with cyclophosphamide and Busulfan in vitro (human Sertoli cells) and in prepubescent mice. We assessed the effects of the exosomes by analyzing cell proliferation assays, molecular analysis, immunohistochemistry, body weight change, serum hormone levels, and fertility rate. Our data indicates the protective effect of h-UCMSC-Exo by preserving the SSC niche and preventing testicular damage in mice. Interestingly, mice that received multiple injections of h-UCMSC-Exo showed significantly higher fertility rates and serum testosterone levels (p < 0.01). Our study demonstrates that h-UCMSC-Exo can potentially be a novel fertility protection approach in prepubertal boys triaged for chemotherapy treatment.

Immune Regulation of Seminal Plasma on the Endometrial Microenvironment: Physiological and Pathological Conditions

Seminal plasma (SP) accounts for more than 90% of semen volume. It induces inflammation, regulates immune tolerance, and facilitates embryonic development and implantation in the female reproductive tract. In the physiological state, SP promotes endometrial decidualization and causes changes in immune cells such as macrophages, natural killer cells, regulatory T cells, and dendritic cells. This leads to the secretion of cytokines and chemokines and also results in the alteration of miRNA profiles and the expression of genes related to endometrial tolerance and angiogenesis. Together, these changes modulate the endometrial immune microenvironment and contribute to implantation and pregnancy. However, in pathological situations, abnormal alterations in SP due to advanced age or poor diet in men can interfere with a woman's immune adaptation to pregnancy, negatively affecting embryo implantation and even the health of the offspring. Uterine pathologies such as endometriosis and endometritis can cause the endometrium to respond negatively to SP, which can further contribute to pathological progress and interfere with conception. The research on the mechanism of SP in the endometrium is conducive to the development of new targets for intervention to improve reproductive outcomes and may also provide new ideas for semen-assisted treatment of clinical infertility.

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.