The functional capabilities
of skeletal muscle are strongly correlated
with its well-arranged microstructure, consisting of parallelly aligned
myotubes. In case of extensive muscle loss, the endogenous regenerative
capacity is hindered by scar tissue formation, which compromises the
native muscle structure, ultimately leading to severe functional impairment.
To address such an issue, skeletal muscle tissue engineering (SMTE)
attempts to fabricate
in vitro
bioartificial muscle
tissue constructs to assist and accelerate the regeneration process.
Due to its dynamic nature, SMTE strategies must employ suitable biomaterials
(combined with muscle progenitors) and proper 3D architectures. In
light of this, 3D fiber-based strategies are gaining increasing interest
for the generation of hydrogel microfibers as advanced skeletal muscle
constructs. Indeed, hydrogels possess exceptional biomimetic properties,
while the fiber-shaped morphology allows for the creation of geometrical
cues to guarantee proper myoblast alignment. In this review, we summarize
commonly used hydrogels in SMTE and their main properties, and we
discuss the first efforts to engineer hydrogels to guide myoblast
anisotropic orientation. Then, we focus on presenting the main hydrogel
fiber-based techniques for SMTE, including molding, electrospinning,
3D bioprinting, extrusion, and microfluidic spinning. Furthermore,
we describe the effect of external stimulation (i.e., mechanical and
electrical) on such constructs and the application of hydrogel fiber-based
methods on recapitulating complex skeletal muscle tissue interfaces.
Finally, we discuss the future developments in the application of
hydrogel microfibers for SMTE.