Preemptive SOD1 Silencing via Neonatal Intramuscular AAV Therapy Modifies Disease Trajectory in an ALS Mouse Model

Abstract

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neurodegenerative disorder with limited therapeutic options. A major challenge for developing effective therapies is the safe and efficient delivery of genetic cargo to the spinal motor neurons that degenerate in the disease. This is particularly pertinent for SOD1-linked familial ALS, where gene silencing approaches are promising but remain constrained by suboptimal delivery. Here, we establish a gene delivery platform that overcomes this barrier by combining the retrograde transport of rAAV2-retro with an artificial miRNA to achieve pan-spinal SOD1 silencing. A single intramuscular injection of rAAV2-retro-miRNA into neonatal SOD1G93A mice achieved widespread transduction of spinal motor neurons, significant reduction of mutant SOD1 protein, and conferred multifaceted therapeutic benefits. Treated mice exhibited delayed disease onset, extended lifespan, preserved motor function, reduced neuroinflammation, and protection of neuromuscular junctions and spinal motor neurons. These findings establish the rAAV2-retro-miRNA platform as a versatile and efficient tool for spinal motor neuron-targeted gene silencing, addressing the delivery challenge and providing a foundation for further development in motor neuron diseases.