Effect of 3D-Printable Anisotropic Fibrous Hydrogels on Fabricating Artificial Skeletal Muscle Constructs

The use of fibrous hydrogel constructs is a promising strategy in tissue engineering because of their ability to closely mimic the anisotropic structure of biological tissues. In skeletal muscle tissue engineering, fiber alignment is considered a crucial factor for achieving muscle functions originating from the uniaxially aligned structure of myofibers; however, the fabrication process of hydrogel constructs with aligned fibers requires complex and laborious techniques. In this study, the effect of 3D-printed constructs with randomly oriented fibers on myoblast differentiation is evaluated. To this end, 3D-printable gelatin methacryloyl (GelMA) hydrogel microfibers through the mechanical fragmentation of electrospun GelMA sheets is prepared. The bulk rheological and tensile properties of the hydrogels with microfibers are stronger than those of the hydrogels without microfibers. Interestingly, when myoblast-embedded constructs are 3D-printed with and without randomly oriented GelMA hydrogel microfibers and incubated for cell differentiation, the microfibers in the constructs effectively promote myotubule-like cell formation. In addition, the uniaxial 3D printed design enables anisotropic myotubule formation. This shows that hydrogels with only fibers distributed randomly can be applied to achieve more effective artificial muscle constructs than those achieved using normal bulk hydrogels and are easier to use than aligned fibers.