Injectable remote magnetic nanofiber/hydrogel multiscale scaffold for functional anisotropic skeletal muscle regeneration

Developing an injectable anisotropic scaffold with precisely topographic cues to induce 3D cellular organization plays a critical role in volumetric muscle loss (VML) repair in vivo. However, controlling aligned myofiber regeneration in vivo based on previous injectable scaffolds continues to prove challenging, especially in a 3D configuration. Herein, we prepare the monodisperse remote magnetic controlled short nanofibers (MSNFs) with a high yield using an advanced coaxial electrospinning-cyrocutting method. An injectable anisotropic MSNF/Gel nanofiber/hydrogel scaffold based on MSNFs within photocurable hydrogel is further designed, showing the ability to guide 3D cellular alignment and organization by the precise microarchitecture control via a remote magnetic field. MSNF/Gel anisotropic scaffolds were able to recreate the macroscale and microscale topographical features of orbicular muscle and bipennate muscle mimicking their anatomical locations. Furthermore, the resultant MSNF/Gel anisotropic scaffolds significantly enhanced aligned myofiber formation in vivo and improved functional recovery of injured muscles in animal VML models. In summary, this approach offers a new promising tissue engineering strategy not only for the aligned myofiber formation for enhancing skeletal muscle regeneration in vivo but also for other biofabrication of living constructs containing complex anisotropy in vitro.