Search Results (11)

Sarcopenia is a progressive loss of skeletal muscle mass and strength with major clinical and economic consequences. While traditional models emphasize mitochondrial dysfunction, inflammation, and proteostasis imbalance, emerging data highlight a neurogenic component involving motor neuron loss, fiber denervation, neuromuscular junction remodeling, and disrupted trophic signaling. To synthesize current evidence on neurogenic mechanisms of sarcopenia revealed by next-generation sequencing and related multi-omics, to map molecular networks across cell types, and to outline translational opportunities for diagnostics and targeted therapy. A narrative review of human and animal studies indexed in PubMed, Web of Science, and Scopus through November 2025. Search terms combined sarcopenia, denervation, neuromuscular junction, neurotrophic signaling, genomics, transcriptomics, epigenomics, single-cell, and spatial transcriptomics. Eligible studies reported omics or physiological endpoints related to neuromuscular function. Convergent omics data support a central role of the nervous system in the onset and progression of sarcopenia. Genetic and regulatory factors linked to denervation, transcriptomic signatures of junctional disassembly, and cell-specific dysfunctions in motor neurons, Schwann cells, satellite cells, and fibro-adipogenic progenitors have been identified. Epigenetic and transcriptional networks underlying neuromuscular homeostasis, along with candidate circulating biomarkers, provide targets for clinical translation. Neurogenic sarcopenia represents a tractable target for precision prevention and therapy. Integration of multi-omics, artificial intelligence, and advanced models such as innervated organoids and NMJ-on-chip systems can accelerate target validation and enable personalized strategies to preserve neuromuscular function. Full article

Proteomics of dystrophic muscle samples is limited by the amount of protein that can be extracted from patient biopsies. Cells and tissues derived from patient-derived induced pluripotent stem cells (iPSCs) can be an expandable alternative source. We have patterned iPSCs from three Duchenne muscular dystrophy (DMD) patient lines into skeletal muscle cells using a two-dimensional as well as our three-dimensional organoid differentiation system. Probes with sufficient protein amounts could be extracted and prepared for mass spectrometry. In total, 3007 proteins in 2D and 2709 proteins in 3D were detected in DMD patient probes. A total of 83 proteins in 2D and 338 proteins in 3D can be described as differentially expressed between DMD and control patient probes in a post hoc test. We have identified and we propose Myosin-9, Collagen 18A, Tropomyosin 1, BASP1, RUVBL1, and NCAM1 as proteins specifically altered in their expression in DMD for further investigation. Proteomics of skeletal muscle organoids resulted in greater consistency of results between cell lines in comparison to the two-dimensional myogenic differentiation protocol. Full article

Background: Duchenne muscular dystrophy (DMD), which affects 1 in 3500 to 5000 newborn boys worldwide, is characterized by progressive skeletal muscle weakness and degeneration. The reduced muscle regeneration capacity presented by patients is associated with increased fibrosis. Satellite cells (SCs) are skeletal muscle stem cells that play an important role in adult muscle maintenance and regeneration. The absence or mutation of dystrophin in DMD is hypothesized to impair SC asymmetric division, leading to cell cycle arrest. Methods: To overcome the limited availability of biopsies from DMD patients, we used our 3D skeletal muscle organoid (SMO) system, which delivers a stable population of myogenic progenitors (MPs) in dormant, activated, and committed stages, to perform SMO cultures using three DMD patient-derived iPSC lines. Results: The results of scRNA-seq analysis of three DMD SMO cultures versus two healthy, non-isogenic, SMO cultures indicate reduced MP populations with constant activation and differentiation, trending toward embryonic and immature myotubes. Mapping our data onto the human myogenic reference atlas, together with primary SC scRNA-seq data, indicated a more immature developmental stage of DMD organoid-derived MPs. DMD fibro-adipogenic progenitors (FAPs) appear to be activated in SMOs. Conclusions: Our organoid system provides a promising model for studying muscular dystrophies in vitro, especially in the case of early developmental onset, and a methodology for overcoming the bottleneck of limited patient material for skeletal muscle disease modeling. Full article

Background: Three-dimensional skeletal muscle organoids (3D SkMO) are becoming of increasing interest for preclinical studies in Duchenne muscular dystrophy (DMD), provided that the used platform demonstrates the possibility to form functional and reproducible 3D SkMOs, to investigate on potential patient-related phenotypic differences. Methods: In this study, we employed fibrin-based 3D skeletal muscle organoids derived from immortalized myogenic precursors of DMD patients carrying either a stop codon mutation in exon 59 or a 48–50 deletion. We compared dystrophic lines with a healthy wild-type control (HWT) by assessing microtissue formation ability, contractile function at multiple timepoints along with intracellular calcium dynamics via calcium imaging, as well as expression of myogenic markers. Results: We found patient-specific structural and functional differences in the early stages of 3D SkMO development. Contractile force, measured as both single twitch and tetanic responses, was significantly lower in dystrophic 3D SkMOs compared to HWT, with the most pronounced differences observed at day 7 of differentiation. However, these disparities diminished over time under similar culturing conditions and in the absence of continuous nerve-like stimulation, suggesting that the primary deficit lies in delayed myogenic maturation, as also supported by gene expression analysis. Conclusions: Our results underline that, despite the initial maturation delay, DMD muscle precursors retain the capacity to form functional 3D SkMOs once this intrinsic lag is overcome. This suggests a critical role of dystrophin in early myogenic development, while contraction-induced stress and/or an inflammatory microenvironment are essential to fully recapitulate dystrophic phenotypes in 3D SkMOs. Full article

Organoids are self-organized, three-dimensional structures derived from stem cells that can mimic the structure and physiology of human organs. Patient-specific induced pluripotent stem cells (iPSCs) and 3D organoid model systems allow cells to be analyzed in a controlled environment to simulate the characteristics of a given disease by modeling the underlying pathophysiology. The recent development of 3D cell models has offered the scientific community an exceptionally valuable tool in the study of rare diseases, overcoming the limited availability of biological samples and the limitations of animal models. This review provides an overview of iPSC models and genetic engineering techniques used to develop organoids. In particular, some of the models applied to the study of rare neuronal, muscular and skeletal diseases are described. Furthermore, the limitations and potential of developing new therapeutic approaches are discussed. Full article

Neuromuscular diseases (NMDs) are a genetically or clinically heterogeneous group of diseases that involve injury or dysfunction of neuromuscular tissue components, including peripheral motor neurons, skeletal muscles, and neuromuscular junctions. To study NMDs and develop potential therapies, remarkable progress has been made in generating in vitro neuromuscular models using engineering approaches to recapitulate the complex physical and biochemical microenvironments of 3D human neuromuscular tissues. In this review, we discuss recent studies focusing on the development of in vitro co-culture models of human motor neurons and skeletal muscles, with the pros and cons of each approach. Furthermore, we explain how neuromuscular in vitro models recapitulate certain aspects of specific NMDs, including amyotrophic lateral sclerosis and muscular dystrophy. Research on neuromuscular organoids (NMO) will continue to co-develop to better mimic tissues in vivo and will provide a better understanding of the development of the neuromuscular tissue, mechanisms of NMD action, and tools applicable to preclinical studies, including drug screening and toxicity tests. Full article

Cultivated meat is a nascent technology that aims to create an environmentally and animal-friendly alternative to conventional meat. Producing skeletal muscle tissue in an animal-free system allowing for high levels of myofusion and maturation is important for the nutritional and sensorial value of cultivated meat. Alginate is an attractive biomaterial to support muscle formation as it is food-safe, sustainable and cheap and can be crosslinked using non-toxic methods. Although alginate can be functionalized to promote cell attachment, limitations in its mechanical properties, including form, viscosity, and stress relaxation, hinder the cellular capacity for myogenic differentiation and maturation in alginate-based hydrogels. Here, we show that the addition of electrospun short-stranded zein fibers increased hydrogel degradation, resulting in faster compaction, improved cell–gel interaction, and enhanced alignment of bovine muscle precursor cells. We conclude that fiber-hydrogel composites are a promising approach to support optimal formation of 3D constructs, by improving tissue stability and thus prolonging culture duration. Together, this improves muscle-related protein content by facilitating myogenic differentiation and priming muscle organoids for maturation. Full article

Motor neuron diseases (MNDs) are a heterogeneous group of disorders that affect the cranial and/or spinal motor neurons (spMNs), spinal sensory neurons and the muscular system. Although they have been investigated for decades, we still lack a comprehensive understanding of the underlying molecular mechanisms; and therefore, efficacious therapies are scarce. Model organisms and relatively simple two-dimensional cell culture systems have been instrumental in our current knowledge of neuromuscular disease pathology; however, in the recent years, human 3D in vitro models have transformed the disease-modeling landscape. While cerebral organoids have been pursued the most, interest in spinal cord organoids (SCOs) is now also increasing. Pluripotent stem cell (PSC)-based protocols to generate SpC-like structures, sometimes including the adjacent mesoderm and derived skeletal muscle, are constantly being refined and applied to study early human neuromuscular development and disease. In this review, we outline the evolution of human PSC-derived models for generating spMN and recapitulating SpC development. We also discuss how these models have been applied to exploring the basis of human neurodevelopmental and neurodegenerative diseases. Finally, we provide an overview of the main challenges to overcome in order to generate more physiologically relevant human SpC models and propose some exciting new perspectives. Full article

Integration of non-coding RNAs and miRNAs with physiological processes in animals, including nutrient metabolism, is an important new focus. Twenty-three transporter proteins control cellular zinc homeostasis. The transporter Zip14 (Slc39a14) responds to proinflammatory stimuli. Using enterocyte-specific Zip14 knockout mice and RNA-sequencing and quantitative polymerase chain reaction (qPCR), we conducted transcriptome profiling of proximal small intestine, where Zip14 is highly expressed, using RNA from whole intestine tissue, isolated intestinal epithelial cells (IECs) and intestinal organoids. H19, U90926, Meg3, Bvht, Pvt1, Neat1 and miR-7027 were among the most highly expressed genes. Enterocyte-specific deletion of Zip14 demonstrated tissue specific expression, as such these changes were not observed with skeletal muscle. Chromatin immunoprecipitation (ChIP) assays of chromatin from isolated intestinal epithelial cells showed that enterocyte-specific Zip14 deletion enhanced binding of proinflammatory transcription factors (TFs) signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa beta (NF-ĸβ) to promoters of H19, Meg3 and U90926. We conclude enterocyte-specific ablation of Zip14 restricts changes in those RNAs to the intestine. Binding of proinflammatory TFs, NF-ĸβ and STAT3 to the H19, Meg3 and U90926 promoters is consistent with a model where Zip14 ablation, leads to increased TF occupancy, allowing epigenetic regulation of specific lncRNA genes. Full article

In vitro organoids derived from human pluripotent stem cells (hPSCs) have been developed as essential tools to study the underlying mechanisms of human development and diseases owing to their structural and physiological similarity to corresponding organs. Despite recent advances, there are a few methodologies for three-dimensional (3D) skeletal muscle differentiation, which focus on the terminal differentiation into myofibers and investigate the potential of modeling neuromuscular disorders and muscular dystrophies. However, these methodologies cannot recapitulate the developmental processes and lack regenerative capacity. In this study, we developed a new method to differentiate hPSCs into a 3D human skeletal muscle organoid (hSkMO). This organoid model could recapitulate the myogenesis process and possesses regenerative capacities of sustainable satellite cells (SCs), which are adult muscle stem/progenitor cells capable of self-renewal and myogenic differentiation. Our 3D model demonstrated myogenesis through the sequential occurrence of multiple myogenic cell types from SCs to myocytes. Notably, we detected quiescent, non-dividing SCs throughout the hSkMO differentiation in long-term culture. They were activated and differentiated to reconstitute muscle tissue upon damage. Thus, hSkMOs can recapitulate human skeletal muscle development and regeneration and may provide a new model for studying human skeletal muscles and related diseases. Full article

Induced pluripotent stem cells (iPSCs) obtained by reprogramming primary somatic cells have revolutionized the fields of cell biology and disease modeling. However, the number protocols for generating mature muscle fibers with sarcolemmal organization using iPSCs remain limited, and partly mimic the complexity of mature skeletal muscle. Methods: We used a novel combination of small molecules added in a precise sequence for the simultaneous codifferentiation of human iPSCs into skeletal muscle cells and motor neurons. Results: We show that the presence of both cell types reduces the production time for millimeter-long multinucleated muscle fibers with sarcolemmal organization. Muscle fiber contractions are visible in 19–21 days, and can be maintained over long period thanks to the production of innervated multinucleated mature skeletal muscle fibers with autonomous cell regeneration of PAX7-positive cells and extracellular matrix synthesis. The sequential addition of specific molecules recapitulates key steps of human peripheral neurogenesis and myogenesis. Furthermore, this organoid-like culture can be used for functional evaluation and drug screening. Conclusion: Our protocol, which is applicable to hiPSCs from healthy individuals, was validated in Duchenne Muscular Dystrophy, Myotonic Dystrophy, Facio-Scapulo-Humeral Dystrophy and type 2A Limb-Girdle Muscular Dystrophy, opening new paths for the exploration of muscle differentiation, disease modeling and drug discovery. Full article