(325c) One-Step Fabrication of Multi-Channel Hydrogel Scaffolds Using Chaotic Advection: Bioprinting of Pre-Vascularized Muscle-like Tissues

The biofabrication of living constructs containing hollow channels is critical for manufacturing thick tissues. However, current technologies are limited in their effectiveness in the fabrication of scaffolds with channels with diameters smaller than hundreds of micrometers. We demonstrate that the co-extrusion of cell-laden hydrogels and sacrificial materials through printheads containing Kenics static mixing (KSM) elements enables the continuous and one-step fabrication of thin hydrogel filament-like scaffolds (1 mm in diameter) containing dozens of hollow microchannels with widths as small as a single cell. We bioprinted pre-vascularized skeletal muscle-like filaments by loading murine myoblasts (C2C12 cells) in GelMA-alginate hydrogels and using hydroxyethyl cellulose (HEC) as a sacrificial material. We observed higher viability and metabolic activity in scaffolds with hollow multi-channels than in solid constructs. The presence of hollow channels promoted the expression of Ki67 (a proliferation biomarker), mitigated the expression of hypoxia-inducible factor 1-alpha (HIF1-α), and markedly enhanced cell alignment (i.e., 82% of muscle myofibrils aligned (in ±10°) to the main direction of the microchannels after seven days of culture). The emergence of sarcomeric α-actin was verified through immunofluorescence and gene expression. Overall, this work presents what we envision will be an effective and practical tool for the fabrication of pre-vascularized engineered tissues.