Bioprinting 3D muscle tissue supplemented with endothelial-spheroids for neuromuscular junction model.

This article focuses on the development of a hybrid 3D bioprinted muscle construct integrating human muscle progenitor cells (hMPCs) and human umbilical vein endothelial cell (HUVEC) spheroids to enhance vascularization and neuromuscular junction (NMJ) formation in vitro. Using a combination of in situ electric field-assisted bioprinting (E-printing) to align and stimulate hMPCs within a methacrylated muscle-decellularized extracellular matrix (MdECM-MA) bioink, and microdroplet-based spheroid-forming bioprinting (MDS-printing) to deposit HUVEC spheroids, the study achieved improved myogenesis, angiogenesis, and NMJ formation compared to conventional mixed-cell constructs. The hybrid constructs demonstrated enhanced expression of myogenic, angiogenic, and NMJ-related genes, as well as superior mechanical properties and cellular organization. Additionally, co-culture with motor neuron-like NSC-34 spheroids in a simplified muscle-chip model showed accelerated NMJ development, suggesting the platform’s potential for studying neuromuscular disorders and testing therapeutics in a physiologically relevant environment.