Computational fluid dynamics in 3D-printed scaffolds with different strand-orientation in perfusion bioreactors

Bone tissue engineering strategies use fluid flow dynamics inside 3D-scaffolds in perfusion, bioreactors mechanically stimulate cells in these scaffolds. Fluid flow dynamics depends on the bioreactor’s inlet flow rate and 3D-scaffold architecture. We aimed to employ a computational evaluation to assess fluid dynamics in 3D-printed scaffolds with different angular orientations between strands in each layer inside a perfusion bioreactor at different inlet flow rates. 3D-printed cubic scaffolds (0.6×0.6×0.6 cm; total volume 216×10^-3 cm³) containing strands (diameter 100 µm) with regular internal structure and different angular orientation (30°, 45°, 60°, and 90° between strands in each layer) were used for modeling. The finite element method showed that the perfusion bioreactor’s inlet flow rate (0.02, 0.1, 0.5 mL/min) was linearly related to average fluid velocity, average fluid shear stress, and average wall shear stress inside 3D-printed scaffolds with different angular orientation (30°, 45°, 60°, 90°) between strands in each layer. At all inlet flow rates, strands at 30° angular orientation increased average fluid velocity (1.2-1.5-fold), average fluid shear stress (6-10-fold), and average wall shear stress (1.4-2-fold) compared to strands at 45°, 60°, and 90° angular orientation providing similar results. In conclusion, significant local changes in fluid dynamics inside 3D-printed scaffolds result from varying the degree of angular orientation between strands in each layer, and the perfusion bioreactor’s inlet flow rate. By decreasing the angular orientation between strands in each layer and increasing the inlet flow rate of a perfusion bioreactor, the magnitude and distribution of fluid velocity, fluid shear stress, and wall shear stress inside the scaffold increased. The average fluid velocity, average fluid shear stress, and average wall shear stress inside the scaffold within the bioreactor increased linearly with the inlet flow rate. This might have important implications for bone tissue engineering strategies using cells, scaffolds, and bioreactors.