Computational Analysis of Exerting Oscillatory Fluid Flow into 3D Bone Scaffolds with Different Pore Architec-tures

Background: Stem cells are subjected to mechanical and chemical stimulations to differentiate into the target cell. One of the most common types of mechanical stimulations is the use of bioreactors to induce shear stress on the cell surface. The factors affecting on the shear stress include: scaffold pore and the type of flow applied to the cell. Experiments showed that the use of oscillatory bioreactor facilitates the osteogenic differen-tiation of stem cells. In this study, distribution of shear stress in 3D bone scaffolds with different pore shapes as a result of oscillating fluid flow has been investigated.Materials and Methods: Three types of scaffold with spheri-cal, cubical and regular hexagonal pore architectures are mod-eled in the COMSOL (V 5.3a) software. In these scaffolds, the cube length, radius of the sphere and the hexagonal side length are all assumed equal to 200μm. The fluid under oscillation was assumed as a Newtonian fluid. Inlet fluid velocity was applied as v= 30 + 300πsin (2πt) μm/s. outlet boundary condition was assumed as zero-pressure. Computational fluid dynamics was used to solve the problem for the aim of evaluating, distribution of shear stress in 3D scaffolds.Results: The results show that 87% of the scaffold volume with spherical pores, 82% of the scaffold volume with cubic pores and 97% of the scaffold volume with hexagonal pores are under shear stress ranging from 0.1 to10 mPa. Experimental studies have shown that under this range of shear stress, the stem cell differentiate into bone cell. In addition, the results show that shear stress in the center of the scaffold is negligible and reach-es it maximum values near the walls.Conclusion: It can be concluded from the results that the use of scaffolds with hexagonal pores is suitable for bone tissue en-gineering applications. Moreover, the central areas of the scaf-folds experienced low shear stress (<0.1mPa). So, it s predicted that this area is unsuitable for stem cell placement in order to differentiate into bone cells.

Keywords:

Bone Scaffold Geometry , Computational Modeling , Mechanical Modulation , Osteogenic Differentiation