Three-dimensional printing of bioengineered scaffolds to support skeletal muscle regeneration

Volumetric muscle loss (VML) is a debilitating injury to skeletal muscle that compromises daily function and quality of life. One strategy for treating VML is the use of scaffolds to replicate the lost extracellular environment and provide the necessary biological cues to guide the restoration of muscle structure, vascular supply, innervation, and contractile function. Recent advances in 3D-bioprinting provide exciting new opportunities to fabricate injury-specific hydrogel scaffolds that conform to the size and shape of an individual's wound and facilitate the restoration and recovery of muscle mass and function otherwise lost to VML injury. In this review, we provide a synopsis of the pathophysiological characteristics of VML that distinguish it from canonical regeneration. This discussion is followed by an overview of bioengineered strategies for designing scaffolds to recapitulate the physical, chemical, and biological processes of muscle regeneration. We then review three-dimensional printing methodologies used to fabricate hydrogel scaffolds for treating VML injuries. This compilation leads into a discussion of the specific challenges and potential solutions in the design, fabrication, and implementation of 3D-printed scaffolds for treating VML injuries. Our goal is to help advance the ability to restore muscle structure, function, and quality of life following VML.