Oriented micropore-forming bioinks for 3D bioprinting of muscle tissues

Three-dimensional (3D) bioprinting provides a wide avenue for designing complex and customized constructs for regenerative medicine. Bioink formulations in 3D bioprinting usually lack micrometer-sized and interconnected pores for the supply of nutrients and oxygen and biological communications with host tissues, thus limiting cellular activities and therapeutic efficacy. Herein, we present microfibrous pore-forming bioinks for fabricating microporous hydrogels that encapsulate cells for muscle tissue reconstruction. Using phase separation technology, a liquid porogen was embedded into gelatin-based bioinks to form microfibrous structures. Printing bioinks with shear stress enabled the orientation of microfibrous pores along the printing direction, which facilitated the orientation of printed cells and enhanced myoblast differentiation. Moreover, the porous 3D scaffold exhibited promising results in terms of supplying nutrients and oxygen to improve cell survival. Printed tissue constructs were successfully transplanted into muscle tissue defects. This approach holds immense potential for creating anisotropic oriented 3D tissue constructs for applications in cell transplantation, drug screening, and disease modelling.