A Human-Based Functional NMJ System for Personalized ALS Modeling and Drug Testing.

Area of Science:

• Neuroscience
• Stem Cell Biology
• Genetics

Background:

• Neuromuscular junction (NMJ) loss is a key feature in Amyotrophic Lateral Sclerosis (ALS).
• Patient-derived induced pluripotent stem cells (iPSCs) offer a valuable tool for modeling neurodegenerative diseases.
• Developing functional in vitro models is crucial for understanding disease mechanisms and testing therapeutics.

Purpose of the Study:

• To create a functional human neuromuscular junction (NMJ) disease model for Amyotrophic Lateral Sclerosis (ALS).
• To investigate pathological phenotypes of ALS motor neurons (MNs) at the NMJ.
• To evaluate the efficacy of the Deana protocol in correcting ALS-related NMJ deficits.

Main Methods:

• Differentiated motoneurons (MNs) from iPSCs of ALS patients (SOD1 and FUS mutations).
• Integrated ALS-MNs with primary human muscle in a chambered system to form functional NMJs.
• Stimulated MNs and recorded myotube contractions to assess NMJ function using clinically relevant parameters.

Main Results:

• ALS-MNs exhibited pathological phenotypes: increased axonal varicosities, reduced branching/elongation, and increased excitability.
• ALS-MNs formed functional NMJs with wild-type muscle but showed deficits in quantity, fidelity, and fatigue index.
• The Deana protocol successfully corrected NMJ deficits in all tested ALS mutant lines.

Conclusions:

• The developed functional NMJ system serves as a robust platform for studying both familial (fALS) and sporadic (sALS) forms of ALS.
• This model allows for subtype-specific or patient-specific investigations into ALS etiology.
• The system is adaptable for drug testing and patient stratification in ALS research.