Potential effect of geometry on wall shear stress distribution across scaffold surfaces

Bioreactors are used as cell culture systems for growth and maintenance of tissue-engineered scaffolds that serve as three-dimensional (3D) templates for initial cell attachment and subsequent tissue formation. The bioreactors' fluid dynamic environment is known to play a crucial role in the synthesis of cellular components via flow-mediated mechanical stimuli. Computational fluid dynamics (CFD) models in the slow turning lateral vessel (STLV Synthecon, Inc.) were simulated under Couette flow conditions. Systematic research of the wall shear stress (WSS) effects on the scaffold's geometry has been limited. Therefore, direct qualitative and quantitative correlations for WSS values were performed by analyzing and comparing WSS value distributions of two scaffold shapes. Under experimental flow conditions, the disc and prolate spheroid shapes exhibited dissimilar WSS distribution. Nonetheless, when compared to the disc models, the high pressure stagnation region of the spheroid was reduced between 60% and 95%. In the spheroid shape, approximately 40% increase in the shear stress surface exposure to flow ranged from 2 to 3 dyn/cm(2). These values suggest that WSSs are likely affected by scaffold shape and vary little with location within the Synthecon STLV. The proposed simulation studies evidenced the CFD model's flexibility to characterize and quantify forces affecting tissue-engineered scaffold design.