Geometrically Tunable Scaffold-Free Muscle Bioconstructs for Treating Volumetric Muscle Loss.

Traumatic muscle injuries associated with volumetric muscle loss (VML) are characterized by muscle loss beyond intrinsic regeneration capacity, leading to permanent functional impairment. Experimental therapies to augment muscle regeneration, such as cell injection, are limited by low cell transplantation capacity, whereas conventional engineered muscle tissue transplants lack geometric customization to conform to the shape of the muscle defect. Here, a facile approach to engineer scaffold-free high-density muscle tissues in customizable geometric shapes and sizes with high cell viability and integration potential is developed. Using a facile mold-based approach to engineer scaffold-free modular units, transcriptional profiling is performed to uncover the role of pre-formed cell-cell interactions within scaffold-free muscle bioconstructs on myogenesis, an the efficacy of muscle bioconstructs in a mouse model of VML is then evaluated. RNA sequencing revealed that pre-formed cell-cell interactions supported myogenic pathways related to muscle contraction and myofibril assembly, unlike dissociated monodisperse cells. This work further demonstrates the therapeutic efficacy of 3D rectangular solid-shaped scaffold-free transplants in improving muscle function and vascular regeneration. Finally, toward clinical translation, the feasibility of this technology to integrate with medical imaging and artificial intelligence-driven customized bioconstruct design and assembly for intraoperative use is illustrated.