Figure 1.

Skeletal muscle cells and motor neurons were combined into a fabricated 3D co-culture system. C2C12 myoblasts were differentiated into multinucleated myotubes (a) and combined with extracellular matrix (ECM) proteins to create an engineered muscle ring tissue (b). In parallel, mouse embryonic stem cells (HBG3 mESCs) were differentiated into motor neurons (MNs) through the formation of embryoid bodies (EBs) (c and d) and then combined with the engineered muscle tissue and ECM proteins (e) on 3D-printed hydrogel devices (f and g). Once the multi-layered rings sequentially compacted and fused together, they were then placed on a stationary hydrogel skeleton (h). Scale bars, 50 μm (b and d), 500 μm (c), and 10 μm (d, inset).