3D bioprinting and culture of cell-laden constructs
Using the 3D cell printer developed by our group, we fabricated a macroporous construct in a layer-by-layer fashion with the designed size of 30 × 30 mm in cross-section and 0.8 mm (eight layers) in thickness. The cell-laden solution was loaded into a 1-ml syringe, which was set in the nozzle. As previously described, the nozzle system was precisely controlled by the temperature controlling system, and the solution was held at 37 °C. The constructs were immersed in a 3% calcium chloride solution to chemically cross-link sodium alginate after printing. After cross-linking for 3 min, the constructs were gently washed 2 or 3 times and cultured at 37 °C and 5% CO2. Each construct was cultured in a 100-mm petri dish. To each dish, 8 ml of culture medium was added.