Age-Related ECM Stiffness Mediates TRAIL Activation in Muscle Stem Cell Differentiation

Area of Science:

• Muscle stem cell biology
• Extracellular matrix aging
• Regenerative medicine

Background:

• Aging stiffens the extracellular matrix (ECM), hindering muscle regeneration.
• This age-related ECM stiffening causes muscle stem cell (MuSC) dysfunction via poorly understood mechanisms.

Purpose of the Study:

• To investigate age-related molecular changes in MuSC differentiation influenced by ECM stiffness.
• To identify molecular pathways and transcription factors driving MuSC differentiation fates under varying age and stiffness conditions.

Main Methods:

• Young and aged MuSCs were cultured on soft and stiff engineered ECM substrates.
• Single-cell RNA sequencing (scRNA) was employed to analyze molecular changes.
• In vivo collagen cross-linking inhibition using β-aminopropionitrile (BAPN) was performed.

Main Results:

• A distinct age-related fibroblastic population emerged from MuSC differentiation trajectories.
• Activation of the TNF-related apoptosis-inducing ligand (TRAIL) pathway was observed in aged cells on stiff substrates.
• BAPN treatment in aged animals inhibited TRAIL downstream apoptotic targets, including caspase 8 and caspase 3.

Conclusions:

• ECM stiffening with age drives MuSC dysfunction through TRAIL pathway activation.
• Inhibition of ECM cross-linking partially reverses age-related TRAIL pathway activation.
• Age-related muscle functional decline involves inflammatory and apoptotic mediators influenced by ECM stiffness.