Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic, multisystemic disorder characterized by severe, persistent fatigue not alleviated by rest and worsened by minimal exertion, often accompanied by post-exertional malaise (PEM), unrefreshing sleep, cognitive dysfunction, and autonomic disturbances. Despite decades of research, its pathophysiology remains incompletely understood, and skeletal muscle involvement has only recently gained attention. This review aims to provide a historical and pathophysiological synthesis of ME/CFS, emphasizing the pivotal role of skeletal muscle in the onset and persistence of symptoms, and to integrate molecular, cellular, and pathophysiological evidence into a coherent explanatory framework. This is a narrative review of published literature (1990-2025) with critical integration of clinical, biochemical, and experimental data on oxidative stress, mitochondrial dysfunction, Excitation-Contraction (E-C coupling) dysregulation, and muscle secretome alterations in ME/CFS also in relation to post-viral syndromes (e.g., Long COVID). Evidence consistently points to mitochondrial oxidative stress, redox imbalance, impaired Ca2+ handling, and altered signaling pathways in skeletal muscle of patients with ME/CFS. Historical milestones show an evolution from psychogenic interpretations toward recognition of ME/CFS as a biological disorder with neuromuscular and metabolic underpinnings. ME/CFS can be interpreted as a skeletal muscle-metabolic disorder characterized by oxidative distress, mitochondrial dysfunction, and impaired energy regulation, leading to the clinical picture of exercise intolerance and post-exertional malaise. Integrating basic and clinical research through a translational approach provides the foundation for new diagnostic tools, targeted therapies, and biomarkers.

Stomatognathic apparatus and the postural system interact through biomechanical chains, whose neuromuscular properties influence both gross and fine motor coordination. To evaluate changes in body posture and motor functions in children with malocclusion who are treated with palatal expanders, 8 right-handed children (6-12 years) with unilateral posterior crossbite were enrolled in this non-randomized pragmatic longitudinal study. Fine motor skills tests, handgrip strength, 3D body posture analysis, electromyography, thermography and stabilometry were performed before and after the treatment with a Rapid Palatal Expander (RPE) at T0pre (before using RPE), t0Post (immediately after using RPE), T1 (after 21 days of RPE use) and T3 (after 6 months). The positive effect on malocclusion, as demonstrated by reduced mandibular offset, did not result in changes in motor symmetries across time. Velocity variance of stabilometry was reduced during the treatment. The immediate wearing of device only slightly affected the results. The beneficial results at the occlusal level through RPE were not accompanied by changes at the neuromuscular and postural level. Clinicians and practitioners should consider that orthodontics treatments and devices which are adapted due to neuromuscular and posturometric tests may be task and test-related.

The physiological age-related decline in skeletal muscle mass, power, and function is challenging for humans. Skeletal muscle has been recently recognized as a secretory organ, with human myogenic progenitor cells (hMPCs) releasing extracellular vesicles (EVs). Here, we investigate the role of hMPC-derived EVs as mediators in skeletal muscle aging. This heterologous approach enables the analysis of age-related variations in EV burden and their impact on human muscle stem cell function. Therefore, we isolated EVs from hMPCs obtained from vastus lateralis muscle biopsies of young and elderly subjects. Then, we characterized EVs for specific marker, size, and concentration and analyzed their miRNA expression and proteomic profiles to delineate the bioactive cargo that influences recipient cell signaling. Next, we tested the ability of EVs to modulate on hMPCs. Specifically, we treated elderly hMPCs with young EVs and vice versa to analyze viability and differentiation. Our results demonstrate that EVs released by young hMPCs carry regenerative signals that mitigate the functional decline of aged muscle stem cells. Conversely, the EVs derived from elderly hMPCs compromise the regenerative capacity of their younger counterparts. Therefore, these results suggest that hMPCs release EVs and that their cargo is modulated by donor age. Moreover, the EVs significantly modulated hMPCs’ viability and differentiation in cell culture.

Satellite cells (SCs) are essential for skeletal muscle regeneration, but their function declines with aging, often associated with increased pro-apoptotic signaling. This study investigated the impact of in vitro serum starvation—as a model of acute microenvironmental and nutrient stress—on the apoptosis and differentiation potential of human SCs from young and aged donors. SCs were isolated from the Vastus Lateralis of young and aged subjects and cultured in serum-free medium for up to 72 h. We assessed apoptosis through Annexin V/PI staining, TUNEL assays, and caspase activity measurements, while transcriptional profiles were analyzed via RT-PCR. Aged SCs displayed a significantly higher susceptibility to stress-induced apoptosis compared to young controls, marked by the early upregulation of CASP9 and FOXO1. While typical nucleosomal DNA fragmentation was absent, we observed the activation of caspase-3 after 72 h of starvation. In aged cells, activated caspase-3 co-localized with myogenin and extranuclear DNA at sites of nuclear remodeling. Notably, treatment with a pan-caspase inhibitor (z-VAD-fmk) prevented the formation of micronuclei and myotubes, further highlighting a non-apoptotic role for these enzymes. Aged SCs also showed a distinct cell cycle profile characterized by an enlarged G0/G1 phase and altered expression of CDK and CCNB1 genes. Our findings suggest that in human aged SCs, caspase enzymes serve a dual role: mediating a heightened stress response and facilitating the nuclear remodeling necessary for myogenic differentiation. These results clarify how intrinsic aging shapes the response of muscle stem cells under severe environmental and metabolic resource deprivation.

Abstract Prior investigations concerning finishers of the Tor des Géants (TDG) have demonstrated oxi‐inflammatory response. MicroRNAs (miRNAs) have been identified as prospective biomarkers for oxi‐inflammatory and stress responses. This study addressed the acute responses concerning salivary miRNAs, circulating redox markers and urinary exercise‐induced markers during the 2019 TDG. It included seven healthy male participants who successfully completed the race. Biological specimens (blood, saliva, and urine) were collected 1–2 days prior to the race and immediately post‐completion, to assess redox system and glycemia from capillary blood, creatinine and neopterin concentrations from urine, and salivary hsa‐miR‐210 and hsa‐miR‐21. Circulating reactive oxygen species production increased, whereas total antioxidant capacity remained stable. Urinary creatinine and neopterin increased subsequent to the race. Nevertheless, salivary expression levels for both miR‐21 and miR‐210 displayed heterogeneity among participants. Variations in miR‐210 were significantly correlated with changes in heart rate. The extreme mountain ultramarathon incited cumulative stress reflective of muscle damage and immune response activation. Salivary miR‐21 and miR‐210 did not demonstrate acute alterations, indicating that they may not serve as highly responsive markers for the combined hypoxia‐strenuous exercise stressor; this finding may suggest the existence of adaptive mechanisms in finishers that facilitate their capacity to manage extreme challenges.

Hypoxia has been extensively studied as a stressor which pushes human bodily systems to responses and adaptations. Nevertheless, a few evidence exist onto constituent trains of motor unit action potential, despite recent advancements which allow to decompose surface electromyographic signals. This study aimed to investigate motor unit properties from noninvasive approaches during maximal isometric exercise in normobaric hypoxia. Applying a cross-over design, 18 participants (gender-matched, on average age 22.6 y, BMI 23.6 kg/m2, and bioimpedance phase angle 6.4) were exposed twice to hypoxia (FiO2 ≊ 15.0

Complex magnetic fields (CMFs) represent an emerging frontier in regenerative medicine, offering significant potential for innovative therapeutic strategies. This review examined both the theoretical foundations and practical applications of CMFs, focusing on their roles in tissue regeneration and antifungal activity. A comprehensive review of electronic databases (PubMed, Scopus, and Embase) identified seven pivotal studies on in vitro models concerning the CMF topic. Although the number of studies is limited, they collectively highlighted the promising therapeutic potential of CMFs in enhancing wound healing, reducing oxidative stress, and neuroinflammation in diabetic neuropathy, positively influencing mitochondrial function, modulating immune responses, promoting cellular communication, inhibiting the growth and adhesion of Candida albicans to medical surfaces, and enhancing dental pulp stem cell proliferation under inflammatory conditions. These findings suggested that CMFs may offer an eco-sustainable approach, effectively targeting pathogens while preserving human cell integrity. While the current body of research is insightful, it remains in its early stages. To fully leverage the therapeutic potential of CMFs, more comprehensive studies are needed to refine their application and confirm their effectiveness across diverse clinical scenarios. This is essential for integrating CMFs into clinical practice, where they promise to revolutionise treatment approaches.

Ozone (O3) and polystyrene nanoparticles (PNPs) display diffusive behavior that leads to toxicity in many tissues of the adult organism. In this study, we evaluated the interactions between atmospheric pollutants and human muscle, using human myogenic progenitor cells (huMPCs) derived from vastus lateralis skeletal muscle. To achieve this goal, O3 and PNPs were first tested individually to understand the impact of the single pollutant on huMPCs. Subsequently, pollutants were tested in combination to examine their potential synergistic effects, given the simultaneous presence of multiple pollutants in the atmosphere. Cell viability was assessed after treatment with O3 and PNPs, and it seems to be significantly affected in huMPCs exposed to the pollutants, tested both alone and in combination. Similarly, the differentiation capability of treated huMPCs was evaluated, and it was found to be significantly reduced compared to controls, especially when O3 and PNPs are tested in combination. Furthermore, an alteration in the expression of microRNAs involved in myogenic cells’ proliferation and differentiation pathways was found. In light of the correlation between pollutants and increased oxidant levels, and O3’s ability to produce the superoxide anion, superoxide anion levels in huMPCs exposed to pollutants were also assessed, and an increase in this oxidant was recorded. Thus, this preliminary study suggests that exposure to O3 and PNPs affects human muscle, as it alters all the analyzed parameters in huMPCs, filling a gap in the current literature.

The dynamics of physiological systems are impacted by both exercise and hypoxia. Network models can be used to map the interactions between various physiological components in environmental physiology and exercise using the concepts of information theory. This cross‐over study compared three normobaric conditions: control, simulated altitude of 2500 m (fraction of inspired oxygen: ≈ 15.1%) and 3500 m ( ≈ 13.5%), and rest vs. isometric exercise through the lens of network physiology. The 12 participants (6 M and 6 F; 22.25 ± 2.42 years; 23.01 ± 3.24 kg/m 2 ) spent ∼30 min in a tent coupled to an altitude simulator, whose last 3 min consisted of a series of nine unilateral isometric maximal contractions of quadriceps. A metabolic system in breath‐by‐breath mode was used to register cardiorespiratory variables. In‐degree, out‐degree, and transfer entropy (TE) were computed to capture the information flow between variables. A weighted Jaccard Similarity Index was used to assess network similarities. The increase of in exercise over rest was slightly more prominent during hypoxia ( P = 0.054, η 2 p = 0.232). Normoxia–hypoxia networks were more similar during resting than exercise. Rest–exercise networks were less similar to each other during simulated altitude of ∼2500 m ( P = 0.008, η 2 p = 0.353). Neither TE during rest nor during exercise nor the / ratio significantly predicted the occurrence of symptoms. Unexpectedly, compared to mild‐grade hypoxia, low‐grade hypoxia induced more changes in physiological connectivity, with the majority of the connections converging on putative hidden nodes that we suggest are oxygen delivery‐dependent. Network approaches could offer new developments in exercise and environmental physiology.

AbstractMicrogravity (µG) experienced during space flights promotes adaptation in several astronauts’ organs and tissues, with skeletal muscles being the most affected. In response to reduced gravitational loading, muscles (especially, lower limb and antigravity muscles) undergo progressive mass loss and alteration in metabolism, myofiber size, and composition. Skeletal muscle precursor cells (MPCs), also known as satellite cells, are responsible for the growth and maintenance of muscle mass in adult life as well as for muscle regeneration following damage and may have a major role in µG-induced muscle wasting. Despite the great relevance for astronaut health, very few data are available about the effects of real µG on human muscles. Based on the MyoGravity project, this study aimed to analyze: (i) the cellular and transcriptional alterations induced by real µG in human MPCs (huMPCs) and (ii) the response of human skeletal muscle to normal gravitational loading after prolonged exposure to µG. We evaluated the transcriptomic changes induced by µG on board the International Space Station (ISS) in differentiating huMPCs isolated from Vastus lateralis muscle biopsies of a pre-flight astronaut and an age- and sex-matched volunteer, in comparison with the same cells cultured on the ground in standard gravity (1×g) conditions. We found that huMPCs differentiated under real µG conditions showed: (i) upregulation of genes related to cell adhesion, plasma membrane components, and ion transport; (ii) strong downregulation of genes related to the muscle contraction machinery and sarcomere organization; and (iii) downregulation of muscle-specific microRNAs (myomiRs). Moreover, we had the unique opportunity to analyze huMPCs and skeletal muscle tissue of the same astronaut before and 30 h after a long-duration space flight on board the ISS. Prolonged exposure to real µG strongly affected the biology and functionality of the astronaut’s satellite cells, which showed a dramatic reduction of responsiveness to activating stimuli and proliferation rate, morphological changes, and almost inability to fuse into myotubes. RNA-Seq analysis of post- vs. pre-flight muscle tissue showed that genes involved in muscle structure and remodeling are promptly activated after landing following a long-duration space mission. Conversely, genes involved in the myelination process or synapse and neuromuscular junction organization appeared downregulated. Although we have investigated only one astronaut, these results point to a prompt readaptation of the skeletal muscle mechanical components to the normal gravitational loading, but the inability to rapidly recover the physiological muscle myelination/innervation pattern after landing from a long-duration space flight. Together with the persistent functional deficit observed in the astronaut’s satellite cells after prolonged exposure to real µG, these results lead us to hypothesize that a condition of inefficient regeneration is likely to occur in the muscles of post-flight astronauts following damage.

Parkinson's disease (PD) is a debilitant neurodegenerative disease that unveils severe physical, and psychological burdens on patients. To date, there is no effective treatment capable of inverting the disease course, freezing the cognitive impairment, and other non-motor features. Solid lipid nanoparticles (SLNs) can represent a promising approach to provide safe and site-specific delivery of naturally occurring compounds counteracting PD symptoms. In this work, SLNs were purposed for the release of a capsaicin-rich extract (CPS-extract) and investigated for their efficacy in PD pathology. SLNs were prepared by using stearic acid (SA) and Brij 78 as lipid and surfactant, respectively. Different formulation parameters, including drug: lipid ratio and surfactant concentrations were investigated. The selected formulation brings together particle sizes of around 200 nm, high encapsulation efficiency (>80 %), and provides 90 % of CPS release within 24 h, which well fits in the Kosermayer-Peppas model. Differential Scanning Calorimetry (DSC) analysis confirmed the presence of the lipid in the solid crystalline state, while stability studies revealed that CPS-extract SLNs preserve their stability for at least 30 days. Moreover, biological assays, performed on retinoic acid/phorbol 12-myristate 13-acetate (RA/PMA) differentiated SH-SY5Y neuroblastoma cell line, revealed that CPS-extract SLNs possessed a significant protective effect in reducing reactive oxygen species (ROS) increments induced by the neurotoxic agent H2O2.

47-year-old woman suffering from minimal lesion glomerulonephritis previously undergone high-dose steroid therapy and subjected to exacerbations of nephrotic syndrome after therapy discontinuation. It was decided to initiate off-label treatment with Rituximab at a dosage of 375 mg/m2 administred at zero-time, one-month and three months with good therapeutic response and resolution of the clinical laboratory picture. The therapy was well tolerated and had no side effects. This scheme could be an alternative to the conventional therapeutic scheme with steroids or other classes of immunosuppressive drugs, especially in order to avoid problems related to prolonged exposure to steroid therapy.

The prevalence of chronic kidney disease (CKD) continues to rise globally, paralleled by an increase in associated morbidity and mortality, as well as significant implications for patient quality of life and national economies. Chronic kidney disease often progresses unrecognized by patients and physicians, despite diagnosis relying on two simple laboratory measures: estimated glomerular filtration rate (eGFR) and urine analysis. GFR measurement has been grounded in renal physiology, specifically the concept of clearance, with creatinine identified as a suitable endogenous marker for estimating creatinine clearance (CrCl). On this foundation, various equations have been developed to calculate CrCl or estimated GFR (eGFR) using four variables that incorporate creatinine and certain demographic information, such as sex and age. However, creatinine measurement requires standardization to minimize assay variability across laboratories. Moreover, the accuracy of these equations remains contentious in certain patient subgroups. For these reasons, additional mathematical models have been devised to enhance CrCl estimation, for example, when urine collection is impractical, in elderly or debilitated patients, and in individuals with trauma, diabetes, or obesity. Presently, eGFR in adults can be immediately measured and reported using creatinine-based equations traceable through isotope dilution mass spectrometry. In conclusion, leveraging insights from renal physiology, eGFR can be employed clinically for early diagnosis and treatment of CKD, as well as a public health tool to estimate its prevalence.

Satellite cells (SC) proliferation and differentiation play a crucial role in skeletal muscle regeneration after damage and adaptation in response to hypertrophic stimuli. Skeletal muscle ageing affects SC proliferation and differentiation and rely on an enhanced expression of several pro-apoptotic factors. As previous researches demonstrated a modified expression of some genes associated with SC antioxidant and repair activity due to age, in the present project we aimed at assessing the occurrence of apoptotic features in human SCs. Cells were collected from Vastus Lateralis of 9 young (27.3+2.0 years old) and 9 old (71.1+1.8 years old) subjects and cultured in serum-free medium to be collected at 4-24-48 and 72 h. Apoptosis was investigated with Annexin V/PI staining, terminal deoxynucleotidyl transferase (TdT)-mediated nick-end labelling (TUNEL) technique, flow cytometry analysis of Caspase-8 activity and RT-PCR detection of transcripts of apoptotic genes. Interestingly, CAS9 and FOXO1 genes were found upregulated in aged SCs at all-time points tested. Furthermore, we showed the activation of caspase-3 enzyme after 72 h starvation in culture with a nice co-localization with myogenin and TUNEL-positive micronuclei in the elderly. Interestingly, after treatment for 24 h with a broad pan-caspase inhibitor Cbz-Val-Ala-Asp- fluoromethyl-ketone (z-VAD-fmk) no micronuclei neither myotube formation were revealed, suggesting the involvement of caspase enzymes in the nuclear remodelling occurring during myotube formation.

Among the numerous changes that occur in skeletal muscle during aging, the reduced regeneration potential after an injury is largely due to the impaired ability of satellite cells to proliferate and differentiate. Herein, using the freeze-fracture electron microscopy technique, we analyzed both the incidence and size of dihydropyridine receptors (DHPRs) tetrads (4 particles) in cultured myotubes from a young subject (28 years) after 9 days of differentiation and from an old subject (71 years) after 9 and 12 days of differentiation. Compared to young myotubes, at 9 days of differentiation old myotubes exhibited: i) a lower incidence and a smaller size of DHPR clusters and ii) a lower number of complete tetrads. At 12 days of differentiation values of incidence, size and number of complete tetrads in old myotubes were instead comparable with those of young myotubes at 9 days of differentiation. Collectively, these results indicate that in aged myotubes the synthesis process of the proteins involved in the excitation-contraction coupling mechanism, such as the DHPR, is somehow slowed, supporting previous studies evidence of a decrease in the differentiation potential of myotubes from elderly individuals.

Osteosarcoma, among all bone sarcomas, remains a challenge despite the unwavering efforts of medical professionals and scientists. To address this, the scientific community is actively pursuing the development of three-dimensional (3D) in vitro models to faithfully replicate the heterogeneity of osteosarcoma, thereby facilitating the reliable preclinical screening of potential therapies. In this study, we present the latest advancements in engineering an in vitro 3D osteosarcoma model comprising enriched Cancer Stem Cells (CSCs) and a hybrid hydroxyapatite-based scaffold (MgHA/CoII). The improvement of the model occurred through two primary steps: (1) serial passaging of sarcospheres as the CSCs enrichment system and (2) the optimization of the structural configuration of the niche in the scaffold. Two injection-mediated approaches of sarcosphere seeding were designed and extensively characterized in vitro and in vivo Chorioallantoic Membrane (CAM) models to explore their biological properties and tumorigenic potential. The combination of the selected enriched-CSCs and custom-made seeding into the scaffold resulted in the development of 3D osteosarcoma models exhibiting tumor-like features in vitro and tumorigenic properties in vivo. The outcomes of this study offer prospects for future endeavors involving more complex systems capable of replicating specific malignant tumor behaviors (metastatic process and drug resistance), pushing the discovery of new therapeutic strategies for clinical applications.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a demanding medical condition for patients and society. It has raised much more public awareness after the COVID-19 pandemic since ME/CFS and long-COVID patients share many clinical symptoms such as debilitating chronic fatigue. However, unlike long COVID, the etiopathology of ME/CFS remains a mystery despite several decades' research. This review moves from pathophysiology of ME/CFS through the compelling evidence and most interesting hypotheses. It focuses on the pathophysiology of skeletal muscle by proposing the hypothesis that skeletal muscle tissue offers novel opportunities for diagnosis and treatment of this syndrome and that new evidence can help resolve the long-standing debate on terminology.

Previous studies have reported an association between oral microbial dysbiosis and the development and progression of pathologies in the central nervous system. Porphyromonas gingivalis (Pg), the keystone pathogen of the oral cavity, can induce a systemic antibody response measured in patients' sera using enzyme-linked immunosorbent assays. The present case-control study quantified the immune system's response to Pg abundance in the oral cavities of patients affected by different central nervous system pathologies. The study cohort included 87 participants: 23 healthy controls (HC), 17 patients with an acute neurological condition (N-AC), 19 patients with a chronic neurological condition (N-CH), and 28 patients with neurodegenerative disease (N-DEG). The results showed that the Pg abundance in the oral cavity was higher in the N-DEG patients than in the HC (p = 0.0001) and N-AC patients (p = 0.01). In addition, the Pg abundance was higher in the N-CH patients than the HCs (p = 0.005). Only the N-CH patients had more serum anti-Pg antibodies than the HC (p = 0.012). The inadequate response of the immune system of the N-DEG group in producing anti-Pg antibodies was also clearly indicated by an analysis of the ratio between the anti-Pg antibodies quantity and the Pg abundance. Indeed, this ratio was significantly lower between the N-DEG group than all other groups (p = 0.0001, p = 0.002, and p = 0.03 for HC, N-AC, and N-CH, respectively). The immune system's response to Pg abundance in the oral cavity showed a stepwise model: the response diminished progressively from the patients affected with an acute condition to the patients suffering from chronic nervous system disorders and finally to the patients affected by neurodegenerative diseases.