Therapeutic Potential of Follistatin mRNA-Loaded Lipid Nanoparticles for Skeletal Muscle Healing in a Cardiotoxin-Induced Injury Model

Skeletal muscle regeneration and maintenance remain critical challenges in treating various muscular disorders and injuries. While follistatin (FST) has shown promise as a therapeutic agent, its delivery and controlled expression present significant hurdles. This study investigates a mRNA-lipid nanoparticle (LNP) delivery system for FST to enhance muscle healing during regeneration and prevent atrophy. Using a cardiotoxin (CTX)-induced muscle injury model in C2C12 myotubes, we demonstrated that Fst mRNA-LNP treatment significantly protected against cell death and promoted muscle hypertrophy. The treatment maintained cell viability at approximately 6,000 fluorescence units compared to near-zero levels in CTX-only treated cells (P< 0.01) and increased myotube diameter by 30-35% compared to controls (P< 0.0001). Mechanistically, FST acts as a potent antagonist of multiple TGF-β superfamily members, including myostatin and activin A and B, leading to decreased SMAD2/3 phosphorylation and increased Akt phosphorylation. The mRNA-LNP delivery system provided enhanced control over FST expression and improved cellular uptake compared to traditional approaches. These findings provide crucial insights into FST's therapeutic potential and establish a foundation for developing targeted treatments for muscle wasting conditions and injuries.