Cationic nanoparticle targets cGAS-STING axis to drive functional orofacial muscle regeneration

Post-injury orofacial muscle is highly prone to fibrosis, partly due to a dysregulated microenvironment shaped by cell-free DNA (cfDNA). Muscle stem cell, i.e., muscle satellite cell (MuSCs), are key mediators of regeneration and are highly sensitive to such changes, which can shift the repair process from regeneration toward fibrosis. We therefore hypothesize that microenvironment cfDNA modulation could preserve MuSC function and support effective muscle repair. In this study, cationic nanoparticles-polyethyleneimine-functionalized diselenide-bridged mesoporous silica nanoparticles (MSN-PEI)-were employed to capture cfDNA and modulate the dysregulated microenvironment, aiming to investigate how cfDNA clearance promotes orofacial muscle regeneration and influences the interplay between the microenvironment and MuSCs. A freezing-induced masseter muscle injury model in mice was established to mimic orofacial muscle fibrosis. MSN-PEI was delivered at different timepoints post-injury and a combination of histological, functional, molecular and transcriptomic analysis were carried out to examine the therapeutic effects. The results showed that MSN-PEI significantly reduced fibrotic area, enhanced functional recovery of the orofacial muscle, and suppressed cfDNA-associated TLR9 and cGAS-STING signaling, thereby promoting macrophage phenotypic switch and modulating macrophages-MuSCs crosstalk toward a regenerative microenvironment. Single-cell RNA sequencing further revealed that MSN-PEI enhanced IGF signaling while attenuating SPP1 and Galectin signaling in the macrophage to MuSC communication. This study provides solid evidence for the critical role of cfDNA and proper macrophages-MuSCs crosstalk in efficient orofacial muscle regeneration, and highlights cfDNA clearance as a promising strategy for functional orofacial muscle recovery.