FUS-ALS hiPSC-derived astrocytes impair human motor units through both gain-of-toxicity and loss-of-support...

Area of Science:

• Neuroscience
• Stem Cell Biology
• Genetics

Background:

• Astrocytes are critical for neuronal health but their role in amyotrophic lateral sclerosis (ALS) motor neuron pathology is not fully understood.
• Astrocytic support functions are compromised in ALS, impacting neuronal homeostasis.
• Fully human co-culture systems offer a platform to study intercellular dysfunction and identify therapeutic targets in ALS.

Purpose of the Study:

• To investigate the impact of FUS-ALS patient-derived astrocytes on motor neuron networks and neuromuscular junctions (NMJs).
• To characterize the mechanisms of astrocytic dysfunction in ALS using a human motor unit microfluidics model.
• To compare FUS-ALS astrocytes with isogenic controls to identify specific pathological contributions.

Main Methods:

• Utilized human induced pluripotent stem cell (hiPSC)-derived astrocytes from FUS-ALS patients and isogenic controls.
• Incorporated astrocytes into a human motor unit microfluidics model with hiPSC-derived motor neurons and myotubes.
• Employed immunocytochemistry and live-cell recordings to assess motor neuron networks and NMJ formation/functionality.

Main Results:

• FUS-ALS astrocytes showed dysregulated homeostasis, increased reactivity, and inflammatory cytokine secretion.
• Co-culture with FUS-ALS astrocytes led to cytotoxic effects on motor neuron neurite outgrowth and NMJ formation/functionality.
• Isogenic control astrocytes rescued or improved motor neuron and NMJ deficits, indicating a gain-of-toxicity and loss-of-support in ALS astrocytes via the WNT/β-catenin pathway.

Conclusions:

• Astrocytes play a complex and critical role in ALS pathogenesis.
• Dysfunctional astrocytes contribute to motor neuron homeostasis disruption, intercellular network breakdown, and NMJ impairment in ALS.
• Findings provide insights into ALS pathological mechanisms and potential therapeutic strategies targeting astrocytic function.