Three-dimensional tissue engineered skeletal muscle modelling facioscapulohumeral muscular dystrophy

Area of Science:

• Biomedical Engineering
• Musculoskeletal Research
• Genetic Diseases

Background:

• Facioscapulohumeral muscular dystrophy (FSHD) pathogenesis involves DUX4 misexpression in skeletal muscle.
• Existing 2D cell cultures and animal models inadequately replicate FSHD, limiting disease mechanism understanding and therapeutic development.
• A more physiologically relevant model is needed to study FSHD and test potential treatments.

Purpose of the Study:

• To develop and validate a 3D tissue-engineered skeletal muscle (3D-TESM) model for studying FSHD.
• To assess the utility of the 3D-TESM model in recapitulating FSHD pathology and evaluating drug candidates.

Main Methods:

• Generated genetically matched myogenic progenitors from human induced pluripotent stem cells of mosaic FSHD patients.
• Cultured progenitors in a 3D system to create 3D-TESMs.
• Evaluated pathological features, DUX4/DUX4 target gene expression, myofiber size, and contractile force.
• Performed RNA-sequencing to compare 3D-TESMs with 2D myotubes.
• Tested small molecules previously identified in 2D screens for therapeutic effects.

Main Results:

• 3D-TESMs from FSHD patients exhibited key pathological features: DUX4 expression, smaller myofibers, and reduced force.
• RNA-seq confirmed higher DUX4 target gene expression in 3D-TESMs compared to 2D cultures.
• 3D culture conditions improved cellular differentiation compared to 2D.
• Tested small molecules showed no benefit and sometimes impaired contractile force and sarcomere organization in 3D-TESMs.

Conclusions:

• The developed 3D-TESM model effectively recapitulates FSHD pathology and DUX4-related mechanisms.
• This model offers advantages over 2D cultures and animal models for FSHD research.
• The model is suitable for preclinical research on DUX4 pathways and potential therapeutic screening for FSHD.