H-silicene nanosheets as a novel therapeutic approach for disuse muscle atrophy by modulating macrophage polarization.

UNLABELLED

Disuse muscle atrophy (DMA) is characterized by progressive loss of muscle mass and strength, often accompanied by inflammation and macrophage imbalance. Here, we introduce hydrogenated silicene nanosheets (H-silicene) as a novel nanotherapeutic strategy to mitigate DMA through modulating macrophage polarization. H-silicene exhibited good biocompatibility and sustained hydrogen release. In vitro, H-silicene suppressed LPS-induced M1 macrophage activation while promoting M2 polarization, and alleviated myotube atrophy in co-culture assays. In a murine immobilization model, intramuscular H-silicene administration significantly mitigated muscle wasting, reduced fibrosis, and improved functional outcomes. Immunofluorescence staining confirmed a decrease in iNOS/TNF-α cells and an elevated CD206/IL-10 populations in treated muscle. Integrated transcriptomic and proteomic analyses revealed H-silicene-mediated modulation of pathways related to inflammation, oxidative stress, and myogenesis. These findings highlight H-silicene as a promising immunoregulatory nanomaterial for the treatment of disuse-induced muscle atrophy.

METHODS

H-silicene nanosheets were synthesized from CaSi under argon-protected acid treatment and probe-sonicated to obtain dispersible nanosheets. Cytocompatibility was assessed in RAW264.7 and C2C12 cells. Macrophage polarization was analyzed by flow cytometry, ELISA, and immunofluorescence after LPS stimulation ± H-silicene. Conditioned media were applied to differentiated C2C12 myotubes to assess paracrine effects. In vivo, a mouse hindlimb immobilization model was used to induce DMA. Mice received intramuscular injections of H-silicene (250 ppm). Muscle tissue was analyzed by histology, immunofluorescence, behavioral assays, and RNA-seq and proteomics.

RESULTS

H-silicene exhibited low cytotoxicity and dose-dependently suppressed LPS-induced M1 polarization while enhancing M2 polarization. It reduced proinflammatory cytokines and preserved C2C12 myotube morphology in co-culture models. In vivo, H-silicene improved muscle fiber area, reduced collagen deposition, restored grip strength , and improved rotarod performance in DMA mice. Immunostaining confirmed reduced iNOS/TNF-α and increased CD206/IL-10 macrophages. Multi-omics analysis revealed regulation of inflammatory and regenerative signaling, including NF-κB, IL-17, and myoblast differentiation pathways.

CONCLUSION

This study demonstrates that H-silicene alleviates disuse-induced muscle atrophy by promoting the transition from pro-inflammatory M1 macrophages to anti-inflammatory M2 macrophages and remodeling the local immune microenvironment, making it a promising nanotherapeutic for muscle-wasting disorders.