Distal electrical stimulation enhances neuromuscular reinnervation and satellite cell differentiation for functional recovery.

BACKGROUND: Peripheral nerve injuries lead to significant motor deficits, with limited treatment options for full functional recovery. Distal electrical stimulation (E-stim) has shown promise in promoting neuromuscular reinnervation, though its mechanisms are not yet fully understood. This study aims to investigate the regulatory effects of distal E-stim on neuromuscular junction (NMJ) reinnervation and Satellite cell activity in denervated muscle injury. METHODS: Using a sciatic nerve critical gap model in Sprague-Dawley rats (8-week-old, random sex), we applied distal E-stim and assessed neuromuscular and functional recovery through histological, biochemical, and functional evaluations over six weeks. The Sciatic Function Index (SFI) was measured at baseline and at subsequent time points post-injury. We quantified muscle mass, NMJ morphology, and neurotransmitter levels (acetylcholine and acetylcholinesterase), and analyzed muscle fiber electrophysiology using single-muscle electromyography to assess denervated muscle autoelectricity. Additionally, single-cell RNA sequencing was performed to examine gene expression in Satellite cells. RESULTS: Distal E-stim significantly enhanced neuromuscular reinnervation, as evidenced by improved SFI scores, increased muscle mass, and reduced muscle atrophy. Histological analysis showed larger muscle fiber cross-sectional areas and enhanced NMJ structure. Elevated levels of acetylcholine and acetylcholinesterase, along with reduced fibrillation potentials in muscle fibers, further indicated preserved NMJ function. Single-cell RNA sequencing revealed upregulation of genes associated with muscle differentiation and angiogenesis in Satellite cell clusters, suggesting that distal E-stim fosters a regenerative environment. CONCLUSIONS: Our findings demonstrate that distal E-stim promotes functional recovery through NMJ preservation and Satellite cell differentiation, offering novel insights into molecular mechanisms that may enhance electroceutical therapies for peripheral nerve injuries. Further research could optimize E-stim protocols to maximize clinical benefits for patients with neuromuscular impairments.