The protein associated with the silencing information regulator 2-associated enzyme1 (SIRT1) is a highly conserved nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylase and a key member of the sirtuin family. SIRT1 plays an essential role in various cellular physiological processes, primarily localized in the nucleus but also active in the cytoplasm and mitochondria. Recent studies have demonstrated its capacity to delay aging in multiple organs and tissues, although its underlying mechanisms remain incompletely understood. Additionally, SIRT1 exerts a significant influence on metabolic regulation and genetic processes. As the primary source of cellular energy, mitochondria are central to numerous biological functions. Mitochondrial dysfunction has been implicated in the onset and progression of various diseases and is increasingly recognized for its role in aging-related processes. This article investigates the interaction between SIRT1 and mitochondria in regulating reproductive system aging and elucidates their potential mechanisms of action, providing insights for clinical research into reproductive system aging.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disrupts the blood-testis barrier (BTB), resulting in alterations in spermatogenesis. However, whether BTB-related proteins (such as ZO-1, claudin11, N-cadherin, and CX43) are targeted by SARS-CoV-2 remains to be clarified. BTB is a physical barrier between the blood vessels and the seminiferous tubules of the animal testis, and it is one of the tightest blood-tissue barriers in the mammalian body. In this study, we investigated the effects of viral proteins, via ectopic expression of individual viral proteins, on BTB-related proteins, the secretion of immune factors, and the formation and degradation of autophagosomes in human primary Sertoli cells. Our study demonstrated that ectopic expression of viral E (envelope protein) and M (membrane protein) induced the expressions of ZO-1 and claudin11, promoted the formation of autophagosomes, and inhibited autophagy flux. S (spike protein) reduced the expression of ZO-1, N-cadherin, and CX43, induced the expression of claudin11, and inhibited the formation and degradation of autophagosomes. N (nucleocapsid protein) reduced the expression of ZO-1, claudin11, and N-cadherin. All the structural proteins (SPs) E, M, N, and S increased the expression of the FasL gene, and the E protein promoted the expression and secretion of FasL and TGF-β proteins and the expression of IL-1. Blockage of autophagy by specific inhibitors resulted in the suppression of BTB-related proteins by the SPs. Our results indicated that SARS-CoV-2 SPs (E, M, and S) regulate BTB-related proteins through autophagy.

Male germline stem cells (mGSCs), also known as spermatogonial stem cells (SSCs), are the fundamental seed cells of male animal reproductive physiology. However, environmental influences, drugs, and harmful substances often pose challenges to SSCs, such as population reduction and quality decline. With advancements in bioengineering technology and biomaterial technology, an increasing number of novel cell culture methods and techniques have been employed for studying the proliferation and differentiation of SSCs in vitro. This paper provides a review on recent progress in 3D culture techniques for SSCs in vitro; we summarize the microenvironment of SSCs and spermatocyte development, with a focus on scaffold-based culture methods and 3D printing cell culture techniques for SSCs. Additionally, decellularized testicular matrix (DTM) and other biological substrates are utilized through various combinations and approaches to construct an in vitro culture microenvironment suitable for SSC growth. Finally, we present some perspectives on current research trends and potential opportunities within three areas: the 3D printing niche environment, alternative options to DTM utilization, and advancement of the in vitro SSC culture technology system.

Sperm, a crucial gamete for reproduction in sexual reproduction, is generated through the proliferation, differentiation, and morphological transformations of spermatogonial stem cells within the specialized microenvironment of the testes. Replicating this environment artificially presents challenges. However, interdisciplinary advancements in physics, materials science, and cell engineering have facilitated the utilization of innovative materials, technologies, and structures for inducing in vitro sperm production. This article offers a comprehensive overview of research progress on inducing in vitro sperm production by categorizing techniques into two major systems based on matrix-based and non-matrix-based approaches, respectively. Detailed discussions are provided for both types of technology systems through comparisons of their similarities and differences, as well as research advancements. The aim is to provide researchers in this field with a comprehensive panoramic view while presenting our own perspectives and prospects.

Spermatogonial stem cells (SSCs) are the only adult male germline stem cells capable of lifelong self-renewal and differentiation into spermatozoa. Scalable ex vivo survival is essential for endangered species germplasm banking, genetic resource conservation, and male infertility therapy. Here, chitosan (CO) or chitosan oligosaccharide (COS) was cross-linked into injectable, biodegradable 3D hydrogels loaded with the natural astaxanthin (AST). CCK-8 optimization identified 0.3% CO + 0.2% AST (CHAG) and 0.2% COS + 0.2% AST (COAG) as superior formulations. After 7 or 14 d of 3D culture, CHAG yielded significantly more colonies than controls (p < 0.01), with elevated EdU incorporation, alkaline phosphatase activity, and positive OCT4 and PLZF staining, confirming preserved stemness. Caspase-3 expression was markedly reduced, indicating the AST-mediated suppression of oxidative apoptosis. RNA-seq showed distinct transcriptome pathways (p < 0.01): CHAG up-regulated adhesion and ECM–receptor and cell cycle pathways, whereas COAG enriched immune-modulatory and signaling modules, enabling context-specific use. AST-loaded CO/COS hydrogels are inexpensive, cytocompatible, and scalable, doubling as a biomimetic niche that accelerates SSC proliferation while delaying senescence. The platform provides a robust, controllable 3D system for SSC expansion and establishes a pre-clinical basis for translating CO/COS/AST composites to reproductive stem cell biotechnology.