Fuentes, J.; Mestre, R.; Guix, M.; Ghailan, I.; Ruiz-Gonzalez, N.; Patino, T.; Sanchez, S.

Advances in 3D bioprinting have opened new possibilities in the development of bioengineered muscle models that mimic the structure and functionality of native tissues. The combination of skeletal muscle tissue and artificial elements promotes diverse innovative solutions of interest in both the biomedical field and the development of biohybrid actuators. However, current bioengineering approaches do not fully recreate the complex fascicle-like hierarchical organization of skeletal muscle, impacting on the muscle maturation process due to a lack of oxygen and nutrients supply in the scaffold inner regions. Here we explored co-axial 3D bioprinting as a strategy towards overcoming this challenge, creating individual/non-fused filaments with controlled thickness that present a fascicle-like organization. Compared to conventional 3D-bioprinting, where cell-laden bioink is disposed by a single syringe, our Pluronic-assisted co-axial 3D-bioprinting system (PACA-3D) creates a physical confinement of the bioink during the extrusion process, effectively obtaining thin and independent printed fibers with controlled shape. Fabrication of skeletal muscle-based actuators with PACA-3D resulted in improved cell differentiation, obtaining stronger bioactuators with increased force output when compared to bioactuators fabricated by conventional 3D bioprinting. The versatility of our technology has been demonstrated using different biomaterials, showing its potential to develop more complex biohybrid tissue-based architectures with improved functionality.