Engineered skeletal muscle recapitulates human muscle development, regeneration and dystrophy

Area of Science:

• Biomedical Engineering
• Stem Cell Biology
• Muscle Physiology

Background:

• Human pluripotent stem cells (hPSCs) offer a promising platform for developing in vitro muscle models.
• Existing models lack the complexity to fully recapitulate in vivo muscle development and disease pathology.
• There is a need for robust, developmentally inspired methods to generate functional skeletal muscle for research.

Purpose of the Study:

• To develop a developmentally inspired protocol for deriving skeletal muscle cells from hPSCs.
• To engineer functional three-dimensional (3D) skeletal muscle constructs for in vitro research.
• To utilize these models for studying skeletal muscle regeneration and modeling genetic muscle diseases like Duchenne muscular dystrophy (DMD).

Main Methods:

• Directed differentiation of hPSCs into embryonic muscle progenitors.
• Induction of primary and secondary fetal myogenesis to form 3D muscle constructs.
• Generation of patient-specific induced pluripotent stem cell (iPSC) lines and CRISPR/Cas9-edited isogenic controls to model DMD.
• Characterization of skeletal muscle organoids (SMOs) and engineered skeletal muscles (ESMs) for structure, function, and cellular composition.

Main Results:

• The protocol successfully recapitulated key embryonic myogenesis steps, yielding functional SMOs and ESMs with a regenerative satellite-like cell pool.
• ESMs demonstrated organotypic maturation and contractile function (up to 5.7 ± 0.5 mN tetanic twitch tension).
• Thyroid hormone treatment enhanced contractile speed, while a cardiotoxin injury model showed functional recovery mediated by satellite-like cells. DMD models exhibited reduced contractility and impaired relaxation due to dystrophin absence, which was rescued by gene editing.

Conclusions:

• A novel method for generating functional human skeletal muscle models from hPSCs was established.
• These models exhibit canonical in vivo skeletal muscle properties, including regeneration capacity.
• The developed platform is suitable for studying muscle development, maturation, disease modeling (e.g., DMD), and repair processes.