Substrate stress relaxation regulates neural stem cell fate commitment

Area of Science:

• Neuroscience
• Biomaterials Science
• Stem Cell Biology

Background:

• Adult neural stem cells (NSCs) in the hippocampus are crucial for learning and memory.
• Understanding NSC fate commitment is vital for addressing neurodegenerative diseases.
• Previous research linked NSC differentiation to extracellular matrix stiffness, but in vivo tissues possess viscoelastic properties.

Purpose of the Study:

• To investigate the impact of substrate viscoelasticity on adult neural stem cell fate commitment.
• To develop a novel cell culture platform for tuning matrix viscoelastic properties.
• To elucidate the molecular mechanisms underlying NSC response to viscoelastic cues.

Main Methods:

• Developed a polyacrylamide-based cell culture platform with tunable viscoelasticity using DNA oligonucleotide cross-links.
• Varied the number of mismatched base pairs to control stress relaxation properties.
• Analyzed NSC differentiation, cytoskeletal dynamics (actin flow), and mechanosensitive protein activation (RhoA).
• Utilized inhibitors for myosin II and focal adhesion kinase to probe molecular pathways.

Main Results:

• Increased substrate stress relaxation promoted astrocytic differentiation of NSCs.
• Viscoelastic substrates decreased intracellular actin flow rates.
• Cyclic activation of RhoA was stimulated on stress-relaxing substrates.
• Inhibiting myosin II or focal adhesion kinase partially reversed lineage changes.

Conclusions:

• The study introduces a novel system for controlling matrix viscoelasticity in cell culture.
• NSC fate commitment is influenced by the integration of viscoelastic cues from the microenvironment.
• Viscoelasticity impacts NSC differentiation through modulation of cytoskeletal dynamics and mechanotransduction pathways involving RhoA.