Sarcopenia, the progressive loss of skeletal muscle mass and function with aging, is a major challenge to healthy longevity due to its profound effects on mobility, metabolism, and overall health. In addition to locomotion, skeletal muscles regulate glucose homeostasis and secrete signaling molecules known as myokines, which influence cognition, cardiovascular function, and immunity. Therefore, preservation of muscle homeostasis is essential for prolonged health span. Age-related muscle decline involves reduced muscle mass and alterations in myofiber composition, which compromises the contractile performance. Myofibers are broadly categorized into slow type I and fast type II fibers; type II fibers are further classified into IIa, IIx, and IIb fibers based on their myosin heavy chain isoforms. Recent studies have identified large Maf transcription factors (Mafa, Mafb, and Maf) as principal regulators of type IIb myofiber formation in mice. Notably, large Mafs reactivate the normally silent type IIb myofiber program in human muscles and show strong associations with fast type II myofiber composition in human muscle biopsies. However, whether high Maf activity can be harnessed to counteract the preferential loss of fast type II myofibers in aging muscles remains unknown. Although therapeutic applications remain limited, elucidation of the transcriptional mechanisms governing myofiber type determination will provide a critical framework to address the open questions related to muscle biology, aging, and human performance. In this review, we discuss both established and emerging regulators of myofiber type, particularly focusing on large Mafs, and highlight the recent advances that have reshaped our understanding of muscle plasticity.

The Japanese government has been promoting the establishment of university-launched startups to support product development and its commercialization in the biotechnology and healthcare sectors. The Tsukuba Clinical Research and Development Organization (T-CReDO) at the University of Tsukuba, along with partnering universities, has been operating the Research Studio Initiative—an accelerator program supporting teams with research-based innovations—since 2018. This program provides mentorship by clinicians and experts with experience in research and development (R&D) and business planning to guide product development and their global expansion. We analyzed data from 23 of the 29 participating teams between FY2018 and FY2022. Results indicated that participating teams progressed in launching businesses and advancing in the R&D stages afterward. Funding acquisition was associated with project progress and intellectual property acquisition. The program played an important role in advancing R&D and achieving funding acquisition for medical startups. Future studies must conduct investigations over time on the process from confirmation of pre-clinical proof of concept (POC) to clinical POC of startups, to identify challenges and their solutions in the current program, and to further improve the educational content of the acceleration program.

Synthetic surgical meshes are widely used for hernia repair; they effectively reduce recurrence rates. Mesh implantation in the abdominal wall is typically employed to study mesh toxicity; however, this site has limitations when evaluating their physical properties. This study proposed the buccal region as a novel implantation site and compared its histopathological outcomes with those of the conventional abdominal method. Three types of synthetic meshes: polypropylene (PP), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF), were implanted in the buccal and abdominal areas of the subjects. Tissue samples were collected and analyzed at 1–2 weeks post implantation. Compared to the abdominal implantation group, the buccal implantation group exhibited muscle layer adhesion and tissue infiltration on both mesh surfaces, although granulation and fibrosis were generally reduced, especially at 2 weeks. Among the meshes, PP demonstrated the highest pathology scores, whereas PTFE exhibited the lowest scores. Buccal implantation allows continuous mesh contact with the tissues involved in mastication and facial movements; this promotes mesh expansion, contraction, and enhanced tissue infiltration. This approach mitigates the disadvantages of conventional abdominal implantation such as mesh detachment and adjacent organ invasion. Therefore, buccal implantation provides a stable platform for pathological evaluation and enables the assessment of various physical properties after long-term implantation, making it a promising new model for assessing mesh biocompatibility.