Mouse In Vitro Spermatogenesis on 3D Bioprinted Scaffolds.

Testes have a complex architecture that is compartmentalized into seminiferous tubules with a diameter of approximatively 200 µm in which the germ cells differentiate, surrounded by a basement membrane and interstitium. 3D bioprinting might be used to recreate the compartmentalized testicular architecture in vitro. Directed by a software program, pneumatic microextrusion printers can deposit 3D layers of hydrogel-encapsulated interstitial cells in a controlled manner by applying pressure. Once macroporous-shaped scaffolds resembling seminiferous tubules have been bioprinted with interstitial cells, the epithelial cell fraction can be seeded in the macropores to resemble the in vivo testicular architecture. Moreover, macropores can serve as a delimitation for all testicular cells to reorganize and improve the supply of nutrients to cells through the 3D constructs.

Empowering tomorrow's leaders: the impact of the 15th Network of Young Researchers in Andrology (NYRA) meeting on male reproductive health and interdisciplinary collaboration.

The 15th Network of Young Researchers in Andrology (NYRA) meeting, held at the Palace de Caux, Switzerland, served as a valuable platform to disseminate cutting-edge research and facilitate interactions among early-career researchers and trainees in andrology from around the world. Preceding the 22nd European Testis Workshop, the 2-day event brought together participants from a variety of countries to discuss a range of topics pertaining to men's reproductive health and biology. Specific focuses included piRNAs in mammalian reproduction, biomolecules enhancing sperm physiology, advances in in vitro spermatogenesis, reproductive strategies across species, and career development. A dedicated 'scientific speed-dating' social event also stood out, encouraging cross-disciplinary collaborations and strengthening ties within the scientific community. The high participation rate of the meeting highlighted its value in connecting the andrology community. Finally, the announcement of NYRA's merger with the European Academy of Andrology (EAA) marked a pivotal moment, enabling NYRA to support young researchers while collaborating with the EAA to advance andrology research. The 15th NYRA meeting played a crucial role in enhancing knowledge dissemination and andrology research, empowering young researchers, and addressing key challenges in male infertility.

Shaping the future of male reproductive health: fostering talent at the 14th Network of Young Researchers in Andrology meeting.

The 14th Network of Young Researchers in Andrology (NYRA) meeting was a 2-day conference held at the University of East Anglia in Norwich, UK, organized by the NYRA. The meeting brought together researchers and experts to discuss and exchange ideas on male infertility and spermatogenesis. The meeting covered a wide range of topics related to male germline research, including the impact of mutations in the male germline on future generations, the use of innovative sequencing tools for the study of male infertility, and the intricate germline epigenome. The impact of aging on spermatogenesis was also discussed, with a focus on the increased DNA fragmentation rates, changes in DNA methylation patterns, and longer telomeres associated with aging sperm. Additionally, progress on fertility preservation options for children undergoing gonadotoxic cancer treatments was presented. The meeting also featured workshops on leadership and career development strategies in science, providing a valuable opportunity for young researchers to learn from experts in the field and exchange ideas with their peers. Overall, the meeting provided a platform for researchers to discuss the latest developments in male germline research, highlighting the importance of empowering young researchers to tackle male reproductive health.

Long-Term Maintenance and Meiotic Entry of Early Germ Cells in Murine Testicular Organoids Functionalized by 3D Printed Scaffolds and Air-Medium Interface Cultivation.

Short-term germ cell survival and central tissue degeneration limit organoid cultures. Here, testicular organoids (TOs) were generated from two different mouse strains in 3D printed one-layer scaffolds (1LS) at the air-medium interface displaying tubule-like structures and Leydig cell functionality supporting long-term survival and differentiation of germ cells to the meiotic phase. Chimeric TOs, consisting of a mixture of primary testicular cells and EGFP+ germline stem (GS) cells, were cultured in two-layer scaffolds (2LSs) for better entrapment. They showed an improved spheroidal morphology consisting of one intact tubule-like structure and surrounding interstitium, representing the functional unit of a testis. However, GS cells did not survive long-term culture. Consequently, further optimization of the culture medium is required to enhance the maintenance and differentiation of germ cells. The opportunities TOs offer to manipulate somatic and germ cells are essential for the study of male infertility and the search for potential therapies.

In-vitro spermatogenesis through testis modelling: Toward the generation of testicular organoids.

BACKGROUND: The testicular organoid concept has recently been introduced in tissue engineering to refer to testicular cell organizations modeling testicular architecture and function. The testicular organoid approach gives control over which and how cells reaggregate, which is not possible in organotypic cultures, thereby extending the applicability of in-vitro spermatogenesis (IVS) systems. However, it remains unclear which culture method and medium allow reassociation of testicular cells into a functional testicular surrogate in-vitro. OBJECTIVE: The aim of this paper is to review the different strategies that have been used in an attempt to create testicular organoids and generate spermatozoa. We want to provide an up-to-date list on culture methodologies and media compositions that have been used and determine their role in regulating tubulogenesis and differentiation of testicular cells. SEARCH METHOD: A literature search was conducted in PubMed, Web of Science, and Scopus to select studies reporting the reorganization of testicular cell suspensions in-vitro, using the keywords: three-dimensional culture, in-vitro spermatogenesis, testicular organoid, testicular scaffold, and tubulogenesis. Papers published before the August 1, 2019, were selected. OUTCOME: Only a limited number of studies have concentrated on recreating the testicular architecture in-vitro. While some advances have been made in the testicular organoid research in terms of cellular reorganization, none of the described culture systems is adequate for the reproduction of both the testicular architecture and IVS. CONCLUSION: Further improvements in culture methodology and medium composition have to be made before being able to provide both testicular tubulogenesis and spermatogenesis in-vitro.