Search Results (455)

Objective: Developing foundational biomaterial platforms for cultured meat research requires 3D co-culture systems capable of supporting multiple relevant cell types in a spatially organized manner. This study aimed to establish a compartmentalized tri-culture hydrogel disc incorporating a lipid-containing barrier phase as a proof-of-concept in vitro model. Methods: Beeswax/alginate (Bw/Algi) hydrogels were fabricated and evaluated for morphology and cytocompatibility as a lipid-containing scaffold component. Fucoidan/alginate (Fu/Algi) hydrogels were prepared at varying fucoidan concentrations and screened to identify conditions compatible with C2C12 viability and early-stage differentiation. A composite beeswax/fucoidan/alginate disc (Bw/Fu/Algi) was then assembled by casting cell-laden Fu/Algi regions (myoblasts, fibroblasts, and endothelial cells), separated by Bw/Algi barrier layers and ionically crosslinked with CaCl₂. Scaffold performance was assessed using standard assays for morphology, cytocompatibility, myogenic marker expression, protein production, and thermal stability. Results: Bw/Algi supported cytocompatible C2C12 attachment and growth, while Fu/Algi exhibited concentration-dependent effects on myogenic marker expression, enabling selection of an optimized fucoidan concentration for 3D assembly. The final Bw/Fu/Algi disc maintained viable compartmentalized tri-culture and supported indirect co-culture through spatial separation by the Bw barrier. Myogenic regions exhibited myogenic marker expression with measurable protein production, and differential scanning calorimetry confirmed structural stability under heating. Conclusion: This work establishes a Bw/Fu/Algi tri-culture disc integrating a lipid-containing barrier component with hydrogel-based myogenic compartments, providing a preliminary platform for multicellular in vitro modeling and scaffold design relevant to cultured meat research. Full article

Fetal skeletal muscle development involves coordinated interactions among myogenic, stromal, vascular, and immune compartments, yet the cellular and molecular programs guiding tissue maturation remain incompletely understood. To address this, we generated a high-resolution single-cell atlas of fetal female goat skeletal muscle and performed trajectory analysis, transcription factor activity profiling, and intercellular communication mapping. Unsupervised clustering identified RUNX2 mesenchymal progenitors, fibro-adipogenic progenitors (FAPs), myofibroblasts, endothelial cells, macrophages, differentiating myocytes, and mature skeletal muscle fibers, revealing a heterogeneous ecosystem in which stromal populations support myogenic progression and vascular and immune cells contribute to tissue organization. Pseudotime analysis traced a maturation continuum from differentiation-competent myocytes to contractile fibers, marked by sequential activation of extracellular matrix remodeling, cytoskeletal stabilization, and sarcomere assembly. KEGG and GO enrichment highlighted stage-specific engagement of ErbB, Hedgehog, and Hippo signaling, as well as cell cycle and ubiquitin-mediated proteolysis pathways, linking proliferation, differentiation, and structural maturation. Transcription factor profiling revealed early-stage proliferative and morphogenetically permissive states driven by E2F4/5, HMGA2, and HAND2, transitioning to late-stage differentiation, ECM remodeling, and tissue stabilization orchestrated by CEBPB, CREB3L1, ELK1, and E2F2. Cell–cell communication analysis showed a developmental redistribution of signaling authority, from ECM-driven, progenitor-centered networks to modular, structurally stabilized interactions. These findings define the cellular, transcriptional, and signaling framework orchestrating fetal skeletal muscle maturation. Full article

Insulin-like growth factor 2 (IGF2) plays a pivotal role in regulating growth and development; however, its functional involvement in skeletal muscle satellite cells (SMSCs) remains incompletely understood. To elucidate the regulatory role of IGF2, goose SMSCs were engineered to overexpress IGF2 via lentiviral transduction, followed by comprehensive transcriptomic profiling. Comparative analysis revealed 2802 differentially expressed genes (DEGs) in IGF2-overexpressing cells relative to controls, comprising 1202 upregulated and 1600 downregulated genes. IGF2 overexpression markedly activated fibrogenic programs, as evidenced by the upregulation of AP-1 complex components (FOS, JUN), extracellular matrix-related genes (COL1A1, COL5A3), and Wnt signaling receptors (FZD1, FZD7). In contrast, genes involved in myogenic differentiation and contractile function were broadly suppressed, including key myogenic transcription factors (MEF2C, MEF2D), sarcomeric structural proteins (MYBPC1, ACTN2, MYOM3), and metabolic enzymes. Through the construction of protein–protein interaction networks coupled with functional enrichment analysis, we observed a concerted suppression of myogenic regulatory networks critical for myofiber formation. Quantitative real-time PCR validation further confirmed the reliability of the transcriptomic data. Collectively, these findings suggest that overexpression of IGF2 induces a phenotypic shift from myoblasts toward a fibroblast-like state, uncoupling proliferation from differentiation while enhancing fibrogenic identity. This study provides novel insights into IGF2-mediated regulatory mechanisms underlying skeletal muscle development and fibrotic processes. Full article

Skeletal muscle differentiation is tightly regulated by membrane potential dynamics and voltage-dependent ion channel activity. Potassium (K⁺) and calcium (Ca²⁺) currents cooperate to orchestrate the transition of myoblasts into fusion-competent myotubes, and alterations in this process are associated with dystrophic phenotypes. Here, we investigated the electrophysiological remodeling accompanying C2C12 myogenesis and the modulatory effects of the polyphenol resveratrol (RES) on calcium voltage-gated channel subunit alpha 1 S (CACNA1S, Cav1.1, L-type) currents. Whole-cell patch-clamp recordings were performed in proliferating and differentiating C2C12 cells to characterize the temporal expression of K⁺ currents and voltage-dependent Ca²⁺ channels (VDCCs). During differentiation, three electrophysiological subpopulations were identified according to K⁺ current profiles: SK4+/EAG−/Kir−, SK4−/EAG+/Kir−, and SK4−/EAG+/Kir+. This sequence paralleled a progressive membrane hyperpolarization from −20 mV to −70 mV, consistent with the physiological maturation of myogenic cells. In C2C12 myocytes, nimodipine-sensitive L-type currents were the only Ca²⁺ conductance observed. Their activation threshold (~−30 mV) and half-activation voltage (V/2 ≈ −12 mV) indicated the co-expression of embryonic and adult Cav1.1 isoforms. Exposure to RES (30 µM, 48 h) produced a depolarizing shift in activation (ΔV/2 ≈ +9 mV) and a reduction in current amplitude across all voltages, consistent with a transition toward the adult splice variant of Cav1.1. These findings suggest that RES promotes electrophysiological maturation of skeletal muscle cells by modulating calcium channel expression and gating behavior. Given its known ability to correct splicing abnormalities in CACNA1S and related genes, resveratrol emerges as a promising pharmacological agent for restoring calcium homeostasis in neuromuscular disorders such as myotonic dystrophy type 1 (DM1). Full article

Background: Aging is accompanied by a progressive decline in skeletal muscle regeneration, largely due to impaired myogenic differentiation. The proprotein convertase FURIN is a key protease responsible for activating several signaling molecules, including precursors of NOTCH receptors, which regulate cell fate and differentiation. In this study, we investigated whether age-associated downregulation of FURIN contributes to impaired NOTCH2/3 signaling and myogenic function. Methods: An initial bioinformatics analysis of public scRNA-seq data from Genotype-Tissue Expression (GTEx) project indicated age-related expression of genes in the NOTCH signaling pathway. In vitro verification used early- and late-passage C2C12 myoblasts as a model of muscle cell aging to compare the expression of these genes. Late-passage C2C12 cells were transiently transfected with FURIN plasmid to assess restoration of differentiation potential, quantified by the fusion index, myogenic marker expression, and morphology. Results: Expression of FURIN, NOTCH2 and NOTCH3 was negatively correlated with age, whereas GZMB increased with age in GTEx dataset. Late-passage myoblasts exhibited impaired myotube formation, reflecting age-associated loss of myogenic capacity. Restoration of FURIN expression in aged myoblasts was associated with reduced GZMB levels, increased expression of embryonic myosin heavy chain IGF1, and partial recovery of myogenic differentiation and myotube formation. Conclusions: These findings suggest that age-associated loss of FURIN contributes to impaired NOTCH2/3 pathways and myogenic dysfunction. Overexpression of FURIN partially rescues the myogenic phenotype and increases expression of early myogenic markers in aged cells, identifying FURIN as a potential regulator of muscle regenerative capacity during aging. We suggest FURIN as a promising candidate target for further investigation into the mechanisms driving aging or age-related decline. Full article

Age-related muscle decline is associated with impaired mitochondrial bioenergetics, altered redox signaling, and reduced myogenic capacity, yet how photobiomodulation (PBM) source characteristics shape these processes under replicative aging remains unclear. Here, we investigated source-specific PBM responses in C2C12 myoblasts using a 660 nm light-emitting diode (LED) and an 830 nm near-infrared (NIR) laser across fluence ranges and replicative stages. Single-cell screening performed at passage 25 identified 5 J/cm² as the optimal fluence for both sources, producing biphasic increases in mitochondrial membrane potential and ROS. Population-level assays in young (≤5 passages) and old (≥30 passages) cells revealed divergent downstream outcomes. LED irradiation elicited stronger metabolic activation and ATP production, particularly in aged cells, whereas NIR irradiation robustly enhanced myogenic fusion in both age groups and partially rescued differentiation deficits in aged myoblasts. Bulk ROS increased significantly after PBM independent of source, while extracellular vesicle release displayed age-dependent source sensitivity, with NIR favoring canonical small EV populations in young cells and LED inducing greater particle release in aged cells. Together, these findings demonstrate that PBM engages conserved mitochondrial signaling while source-specific delivery and wavelength differentially direct metabolic, paracrine, and myogenic outputs under replicative aging conditions. Full article

Myogenic mechanobiology governs how mechanical cues regulate myocyte organization, alignment, and functional maturation; however, in vitro platforms that enable quantitative control and real-time readout of myogenic mechanical microenvironments remain limited. Here, we engineered a pneumatic-driven organ-on-a-chip platform integrating six parallel culture units and a bead-embedded flexible PDMS membrane to deliver cyclic mechanical strain and enable quantitative stress–strain mapping in cardiomyocytes and skeletal muscle cells. Finite element-guided optimization ensured effective membrane deformation, and the platform generated stable and tunable cyclic strain with a strong linear relationship between applied negative pressure (50–700 mbar) and membrane stress and strain. Plasma treatment combined with type I collagen coating restored myogenic cell adhesion and growth on PDMS to levels comparable to standard culture conditions. Under 13% cyclic strain, both cardiomyocytes and skeletal muscle cells exhibited pronounced and highly uniform alignment, with cellular polarity oriented perpendicular to the stretch axis. Moreover, cyclic loading significantly enhanced the expression of contractile maturation markers, including MYH7 in cardiomyocytes and MYH6 in skeletal muscle cells (all p < 0.05), whereas expression of the differentiation regulator MyoG remained unchanged, indicating that mechanical stimulation preferentially promotes structural organization and contractile maturation rather than lineage commitment. Collectively, this quantitatively programmable organ-on-a-chip represents a bioengineered microdevice for studying myogenic mechanobiology, revealing conserved mechanosensitive alignment and maturation responses across myogenic lineages and providing a versatile framework for biomedical engineering research, disease modeling, and mechanotherapeutic screening. Full article

Cultured meat, a sustainable alternative to conventional meat, addresses ethical and environmental challenges in livestock production. Its production relies on bovine muscle stem cells from adult muscle or fetal tissue, whose proliferation and differentiation vary with age and developmental stage. However, the molecular mechanisms underlying these variations remain unclear. RNA sequencing was performed to characterize the transcriptomic landscape of bovine muscle stem cells across developmental stages, including myogenic maturation. Differentially expressed genes and key signaling pathways regulating myogenesis were identified, and the functional impact of modulating the AKT-autophagy pathway on differentiation was assessed. Transcriptomic analysis revealed distinct age-dependent gene expression patterns. It was possible to classify cells into three categories: young undifferentiated, young differentiated, and old differentiated. Young undifferentiated-like cells exhibited upregulation of genes associated with active states during the transitions from quiescence to activation and, ultimately, to commitment, indicating that they had robust differentiation potential. In contrast, aged myogenic samples displayed gene expression profiles that acted as barriers to efficient myogenic differentiation. Notably, modulation of the AKT-autophagy pathway both facilitated the production of very mature myogenic cells and prevented spontaneous differentiation, thereby preserving differentiation capacity in vitro. These findings provide insights into age-dependent muscle stem cell differentiation and suggest strategies to optimize cultured meat production. The appropriate modulation of key signaling pathways may help us to overcome major challenges in achieving scalable and efficient cultured meat manufacturing. Full article

The role of platelet-derived growth factor D (PDGFD) in mesenchymal cells is well-established, but its specific function in skeletal muscle generation remains unknown. This study reveals for the first time PDGFD’s dual regulatory role in myogenesis: it acts both as a “guardian” maintaining the myoblast pool and as an “initiator” driving myogenic differentiation. Through single-cell RNA sequencing analysis of skeletal muscle from Jiangquan Black pigs, we identified PDGFD as a common candidate gene for both muscle and fat development. In the C2C12 cell model, PDGFD knockdown significantly inhibited cell proliferation and promoted apoptosis, while overexpression enhanced viability and inhibited apoptosis, indicating its critical role in maintaining myoprogenic precursor cell homeostasis. Further studies revealed that PDGFD interference downregulated key myogenic differentiation markers MyoD and MyoG, inhibiting differentiation. Its expression peaked during mid-differentiation (D5), suggesting temporal regulation of differentiation. Interestingly, although PDGFD primarily acts through the PI3K/Akt pathway downstream of PDGFR-β, PDGFD knockdown did not show significant synergistic effects with PI3K/Akt pathway activation in inhibiting differentiation. This suggests PDGFD may specifically regulate myogenic differentiation via an independent or parallel signaling axis. This study not only expands the known functions of PDGFD in muscle biology but also provides new insights into the mechanisms by which growth factors coordinate cell fate decisions. Full article

Background: During aging, skeletal muscle mass constantly diminishes and myogenic potential declines. At the cellular level, a decline in mitochondrial function is a hallmark of the aging process and the deficiency of the mitochondrial network contributes to a progressive reduction in muscle mass. Autophagic clearance of mitochondria through the process of mitophagy is required to remove impaired or damaged mitochondria, while mitophagy is a key regulator of muscle maintenance. Dysfunctional degradation of mitochondria is increasingly associated with aging (mitophaging), while mechanical stimuli have been shown to ameliorate the aging-induced impaired muscle mass and function; however, less is known about the potential effects of mechanical loading on mitophaging. The aim of the present study was to investigate the effect of mechanical stretching on mitophagy in aged myoblasts, in vitro. Methods: Cell senescence was replicated using a multiple cell division model of C2C12 myoblasts. The control and aged cells were cultured on elastic membranes and underwent passive stretching using a mechanical loading protocol of 15% elongation for 12 h at a frequency of 1 Hz. Cell signaling and gene expression responses of mitophagy-associated and myogenic regulatory factors (MRFs) were assessed through immunoblotting and qRT-PCR of the cell lysates derived from stretched and non-stretched control and aged myoblasts. Results: Mitophagy factor AMP-activated protein kinase (AMPK), mitochondrial biogenesis stimulator peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1a), and mitophagy/mitochondrial biogenesis factor Parkin were downregulated in control stretched myoblasts compared to non-stretched cells, while the specific mechanical loading protocol used also reduced the phosphorylation of unc-51-like autophagy-activating kinase 1 (p-ULK1) (p < 0.05), as well as the expression of myogenic factor 5 (Myf5) and myogenic factor 4 (myogenin) (p < 0.001). Interestingly, this mechanical loading resulted in increased PGC-1a and Parkin expression (p < 0.05) and induced the previously undetected BCL2 interacting protein 3-like (BNIP3L/NIX) and AMPK expression and p-ULK1 activation in the aged myoblasts. In addition, mechanical stretching differentially affected the expression of MRFs in aged cells, upregulating the early differentiation factor, Myf5 (p < 0.01), while downregulating the late differentiation factor myogenin (p < 0.001). Conclusions: These findings suggest the beneficial effects of mechanical loading on the impaired mitophagy and early differentiation in aged myoblasts, as indicated by the mitophagy initiation and the promotion of mitochondrial biogenesis in these cells. The mechanical loading-induced downregulation of mitophagy and myogenesis in the control myoblasts might indicate their loading-specific differential responses compared to the aged cells. Full article

Background/Objectives: The aim of this study was to assess NB CE-Chirps for diagnosing Superior Semicircular Canal Dehiscence Syndrome (SSCDS) with cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs), and to compare them with Tone Bursts (TBs). Methods: Nine subjects diagnosed with SSCDS were included (four men/five women, median = 61 years, range = 31–79 years). Intensity thresholds at 500 Hz were investigated with both stimuli. A response was also sought when NB CE-Chirps and TBs were delivered at 4000 Hz for c and oVEMPs. Results: Both 500 Hz TBs and 500 Hz NB CE-Chirps significantly differentiated affected ears from healthy ears for cVEMPs (p < 10⁻³ in both cases) and oVEMPs (p < 10⁻³ in both cases). Furthermore, we observed significantly lower intensity thresholds in SSCDS ears with 500 Hz NB CE-Chirps than with 500 Hz TBs for both cVEMPs (p < 10⁻³) and oVEMPs (p = 0.036). Regarding the response rate at 4000 Hz, only TBs consistently showed a response in 100% of cases for the affected ears, with no response in healthy ears for both cVEMPs and oVEMPs. However, there was no significant difference between the response rates obtained at 4000 Hz using TBs and NB CE-Chirps in affected ears (p = 1.000 for cVEMPs and p = 1.000 for oVEMPs). Conclusions: Searching for intensity thresholds with NB CE-Chirps 500 Hz in cVEMPs and oVEMPs is an effective method for diagnosing SSCDS, likely with better frequency specificity than with 500 Hz TBs. Stimulation at 4000 Hz with both TBs and NB CE-Chirps appears to be a promising test for easily screening this syndrome, reducing both sound exposure and the duration of the examination. The possibility to reduce rise time in 4000 Hz TBs may favor this stimulus over NB CE-Chirps at this frequency for this disease. These results should be confirmed in larger cohorts including patients with more severe forms. Full article

Skeletal muscle myogenesis is a crucial factor influencing meat production in livestock. MicroRNAs (miRNAs) play a significant role in skeletal muscle myogenesis. The objective of this study was to identify key miRNAs involved in the process of goat skeletal muscle satellite cell (MuSC) differentiation into myotubes. We performed miRNA expression profiling analysis during the proliferation phase (cultured in growth medium, GM) and the differentiation phase (cultured in differentiation medium for 1 day and 5 days, classified as DM1 and DM5, respectively) of goat skeletal muscle satellite cells (MuSCs). A total of 1846 miRNAs were identified in MuSC samples, of which 677 differentially expressed miRNAs (DEmiRNAs) were screened through pairwise comparisons across three groups (GM vs. DM1, GM vs. DM5, and DM1 vs. DM5), and the results were further confirmed by a quantitative real-time PCR assay. Time-series expression profiling facilitated the categorization of the DEmiRNAs into eight distinct clusters, one of which demonstrated a significantly downregulated expression pattern (p < 0.05). Functional enrichment analysis revealed that the target genes of DEmiRNAs are involved in several pathways that are critical for myogenesis, including Hippo, TGF-β, MAPK and cell adhesion molecules. Interaction network analysis identified 19 miRNAs and 56 mRNAs associated with muscle cell development. Notably, novel-m0047-5p emerged as a key regulator, exhibiting strong negative correlations (r = −0.88 to −0.89, q < 0.01) with muscle-related target genes FOSB, CPT1B, and MYOZ2. These findings elucidate miRNA-mediated regulatory networks in goat myogenesis and provide candidate molecular targets for genetic improvement of meat production traits. Full article

The role of bile acid metabolism within the skeletal muscle microenvironment in sarcopenia remains unclear. This study investigated bile acid alterations and the function of the ATP Binding Cassette Subfamily B Member 1 (ABCB1) transporter in muscle microvascular endothelial cells (MMECs) during aging. Using a sarcopenic mouse model stratified by muscle density, we found elevated deoxycholic acid (DCA) and lithocholic acid (LCA) levels but reduced tauroursodeoxycholic acid (TUDCA) levels in muscle, correlating with downregulated ABCB1/P-glycoprotein expression. In vitro, inhibition of ABCB1 in MMECs impaired bile acid efflux, promoted inflammation, and compromised endothelial health. Conditioned medium from these MMECs reduced the viability, proliferation, and differentiation of C2C12 myoblasts, downregulated myogenic factors, and increased atrophy markers. Furthermore, we identified miR-135a-5p as a direct upstream regulator of ABCB1 in MMECs, and demonstrated that it mediates bile acid efflux impairment and subsequent myoblast dysfunction. Our findings reveal a novel “bile acid–MMEC–muscle” axis in sarcopenia, where miR-135a-5p-mediated ABCB1 downregulation in MMECs disrupts the local bile acid milieu and impairs muscle regeneration, highlighting ABCB1 as a potential therapeutic target for aging-related muscle loss. Full article

Sarcopenia and glucocorticoid-induced myopathy are significant forms of muscle atrophy that pose considerable public health challenges. In this regard, preventing muscle atrophy is crucial for enhancing quality of life and increasing life expectancy. In this study, we investigated the effect of recombinant human KAI1 (rhKAI1) on myogenic differentiation and its protective effect against dexamethasone-induced muscle atrophy. rhKAI1 enhanced myogenic differentiation in both murine C2C12 myoblasts and primary human endometrial stromal cells, as evidenced by upregulation of myogenic regulatory factors and increased myotube formation. These effects were accompanied by increased phosphorylation of Akt and AMPK. In a dexamethasone (Dex)-induced atrophy model, rhKAI1 increased myotube diameter, restored MyHC expression, and reduced the expression of the E3 ligase atrogin-1, accompanied by increased phosphorylation of Akt and AMPK. In addition, rhKAI1 administration improved Dex-induced functional impairment in mice, as reflected by increased grip strength and improved rotarod performance. Molecular analyses further showed that rhKAI1 modulated Dex-induced fiber-type-related gene expression by restoring MYH7 (type I) and reducing MYH4 (type IIb) expression. Collectively, our findings demonstrate that rhKAI1 promotes myogenic differentiation and alleviates several functional and molecular features associated with glucocorticoid-induced muscle deterioration. These results support the potential of rhKAI1 as a candidate molecule for further investigation in steroid-induced muscle dysfunction. Full article

Cancer cachexia is a multifactorial metabolic syndrome characterized by progressive skeletal muscle and adipose tissue loss, systemic inflammation, and poor clinical outcomes, and represents a major unmet clinical need in gastric cancer. Growth Differentiation Factor 15 (GDF15) is a key mediator of cachexia-associated anorexia and tissue wasting; however, the upstream mechanisms regulating its expression in gastric cancer remain poorly defined. Leukemia Inhibitory Factor (LIF), a pleiotropic cytokine implicated in tumor progression and metabolic dysregulation, has emerged as a potential regulator of cachexia-related pathways. Here, we investigated the association between LIF in regulating GDF15 expression and its relationship with metabolic, inflammatory, and body composition alterations in gastric cancer. Transcriptomic profiling of paired neoplastic and non-neoplastic gastric mucosa from 61 gastric cancer patients revealed a significant upregulation of both LIF and GDF15 in tumor tissue, with a strong positive correlation between their expression levels. High GDF15 expression was associated with reduced overall survival, a finding validated in independent TCGA-STAD and ACRG cohorts. Intratumoral bile acid profiling uncovered a marked enrichment of primary bile acids and a depletion of secondary bile acids, resulting in reduced levels of bile acids with endogenous LIF receptor (LIFR) antagonist activity; elevated primary, LIFR non-antagonist bile acids were associated with worse survival outcomes. Clinically, increased LIF and GDF15 expression correlated with weight loss, heightened inflammatory burden, reduced serum protein and albumin levels, and impaired body composition in a sub-cohort of 19 patients. Notably, LIF expression showed a significant inverse association with both lumbar skeletal muscle index (L3SMI) and subcutaneous adipose tissue index (SATI). Mechanistically, experimental models demonstrated that LIF enhances proliferative activity in gastric cancer spheroids and exerts paracrine effects that impair myogenic differentiation and suppress hepatic metabolic gene expression. Collectively, these findings identify the LIF/GDF15 axis as a central driver of cancer-associated cachexia in gastric cancer and highlight LIF signaling as a potential therapeutic target. Full article