ABSTRACT
Despite the crucial role of the extracellular matrix (ECM) in the organotypic organization and function of skeletal muscles, most 3D models do not mimic its specific characteristics, namely its biochemical composition, stiffness, anisotropy, and porosity. Here, a novel 3D in vitro model of muscle extracellular matrix was developed to differentiate myogenic cells (C2C12 line) into myotubes and reproduce their natural cell/cell and cell/matrix interactions. An anisotropic hydrogel mimicking the perimysium was obtained thanks to unidirectional 3D printing of dense collagen with aligned collagen fibrils. The space between the different layers was tuned to generate an intrinsic porosity (100 µm) suitable for nutrient and oxygen diffusion. By modulating the gelling conditions, the mechanical properties of the construct reached those measured in the physiological muscle ECM. The addition of large channels (600 µm) by molding permitted to create a second range of porosity suitable for cell colonization without altering the physical properties of the hydrogel. C2C12 cells embedded in Matrigel®, seeded within the channels, organized in 3D, and differentiated into multinucleated mature myotubes. This organization reproduced the global muscular bundles, i.e., the endomysium encompassing myotubes. These results show that porous and anisotropic dense collagen hydrogels colonized with myoblasts are promising biomaterials to model skeletal muscle.
Highlights
A novel extracellular matrix-like hydrogel increases the physiological relevance of the skeletal muscle model.
Porous and anisotropic dense collagen hydrogels mimic the muscle ECM physical properties.
Unidirectional printing of dense collagen creates a porous and anisotropic scaffold in a single step.
Anisotropic dense collagen hydrogels promote C2C12 differentiation into myotubes and their 3D organization.
Competing Interest Statement
The authors have declared no competing interest.