Continuous chaotic bioprinting of skeletal muscle-like constructs

In this study, chaotic flows are used to biofabricate muscle tissue-like constructs that mimics the hierarchical architecture of native skeletal muscle. Multi-layered and multi-material filaments (~1.2 ​mm in diameter) are easily obtained in a one-step extrusion protocol by using a Kenics static mixer (KSM). These filaments contain intercalated layers (~130 ​μm in thickness) of myoblast-laden gelatin-methacryloyl (GelMA)-alginate and physical barriers composed of alginate. Cells exhibit a high post-printing viability (>85%) and remain highly viable even at 28 days after bioprinting. Alginate barriers prevent cells from migrating to neighboring layers. The spatially controlled microarchitecture achieved here, resembles a muscle fascicle at each intercalated layer. This straightforward approach promotes an effective alignment of cells (~60%) with respect to the filament axis. The expression of myosin and sarcomeric actin was verified at day 28. In summary, we demonstrate the fabrication of a hierarchically structured engineered muscle-like constructs in a continuous and simple fashion using an extrusion-based technique that modulates printing resolution simply by switching the number of KSM elements in the printhead.