Files
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neuromuscular disease characterized by motor neuron degeneration and muscle atrophy, with no effective treatments. Given its complex pathology, my research explores extracellular vesicle (EV)- based therapies to target multiple disease mechanisms in both central and peripheral systems. While skeletal muscle was traditionally considered a secondary consequence of motor neuron loss, emerging evidence suggests it actively contributes to ALS progression via retrograde signaling to the central nervous system. This dissertation establishes skeletal muscle as a viable therapeutic target and investigates EVs from regenerating skeletal muscle and neural progenitor cells (NPCs) as a novel intervention. In the first study, I examined NPC-derived EVs (NPC-EVs) as a neuroprotective therapy, demonstrating their ability to enhance motor neuron survival, reduce oxidative stress, and suppress inflammatory NF-κB signaling in ALS models. These findings highlight NPC- EVs as a safer, cell-free alternative to stem cell transplantation. The second study focused on EVs from regenerating skeletal muscle 14 days post-injury (CTXD14SkM- EVs) as a muscle-targeted ALS therapy. Results showed CTXD14SkM-EVs enhancedmuscle regeneration, shifted macrophage polarization toward an anti-inflammatory (M2) phenotype, and suppressed NF-κB signaling, preserving muscle mass. Recognizing skeletal muscle’s active role in ALS progression, my third study examined the therapeutic potential of EVs from day 3 post-injury regenerating skeletal muscle (CTXSkM-EVs), fibro/adipogenic progenitors (CTXFAP-EVs), and NPC-EVs to maximize therapeutic benefits. Skeletal muscle actively secretes EVs during early regeneration to initiate muscle repair, making them promising candidates. CTXSkM-EVs, representing total muscle-derived EVs, and CTXFAP-EVs, derived from mesenchymal FAPs, promoted myogenesis in atrophic muscle cells, suggesting potential benefits for other muscle- wasting diseases. Additionally, these EVs improved ALS-like motor neuron viability and mitochondrial function, suggesting a role in reducing oxidative stress and preserving cellular energy homeostasis. Beyond individual applications, we introduced a novel mixed EV therapy, combining NPC-EVs with CTXSkM-EVs or CTXFAP-EVs to simultaneously target ALS pathology. In vivo, this therapy mitigated muscle atrophy, promoted regeneration, and suppressed NF-κB signaling in ALS-affected muscle and spinal cord. These findings provide the first evidence that regenerative muscle-derived EVs, particularly when combined with NPC-EVs, offer a promising dual-targeted ALS therapy.