**4. Conclusions**

204 Biomedical Science, Engineering and Technology

gradient. As the fluid reaches the stenosis, the projected surface area decreases resulting in an increase in WSS. Hinds et al. found a similar result in their studies using monocytes (Hinds et al., 2001). Comparing these two results, it can be seen that there is increased

adhesion of leukocytes to ECs in the presence of complex wall shear stress gradients.

Fig. 9. Regional neutrophil (NB4) adhesion in the asymmetric tissue culture model. Copyright Springer, Annals of Biomedical Engineering, 38, 2010, pp. 2798, Neutrophil Adhesion on Endothelial Cells in a Novel Asymmetric Stenosis Model: Effect of Wall Shear Stress Gradients. Rouleau, L.; Copland, I; Tardif, J-C.; Mongrain, R. & Leask, R., Figure 7 (c)

In all instances, the stenosis peak had relatively low adhesion, which is a result of the high shear forces. By the peak of the stenosis, WSS values were appreciably larger than those found in the

& (d) with kind permission from Springer Science+Business Media B.V.

Atherosclerosis is an inflammatory disease. *In vitro* studies of the interaction of inflammatory cells with the endothelium have advanced our understanding of the role of inflammation in atherosclerosis development and progression. Our novel three dimensional dynamic cell culture model of a coronary stenosis has shown the importance of spatial gradients in wall shear stress in EC response and leukocyte attachment. Leukocyte attachment is increased in the proximal and distal regions of the stenosis. The increased attachment occurs in regions where the ECs have an inflamed phenotype. The results suggest that the hemodynamics created by the stenosis geometry create an inflammatory response of the endothelial cells that promotes leukocyte attachment. These results help to explain disease stability in established coronary stenoses.
