Numerical modeling of perfusion flow in irregular scaffolds

Abstract

Direct perfusion of 3D tissue engineered constructs is known to enhance osteogenesis, which can be partly attributed to enhanced nutrient and waste transport. In addition flow mediated shear stresses are known to upregulate osteogenic differentiation and mineralization. A quantification of the hydrodynamic environment is therefore crucial to interpret and compare results of in vitro bioreactor experiments. In this study a 3D CFD model for the creeping perfusion flow inside two irregular bone scaffold structures is developed, simulating the velocity field including shear stress distribution. εCT imaging techniques were used to reconstruct the geometry of both a titanium and a hydroxyapatite scaffold, starting from 430 images with a resolution of 8 μm. The resulting CFD models are built with the 3D unstructured mesher TGrid and solved with the finite volume code Fluent (ANSYS, Inc.). With a flow rate of 0.04ml/min we obtained average wall shear stresses (WSS) of 1.46mPa for the hydroxyapatite scaffold compared to 1.95mPa for the Titanium scaffold. Influence of boundary conditions and scaffold micro architecture heterogeneity has been investigated. This methodology allows to get more insight in the complex concept of tissue engineering and will likely help to understand and eventually improve the fluidmechanical aspects. © 2009 Springer Berlin Heidelberg.