Interstitial fluid flows of bones*

Cancer cells metastasize to bones at the late stages of the disease, leading to high mobility and mortality rate in patients. In this work, we investigate flow structures within the pores of an in-vitro bone model to understand the mechanical micro-environment surrounding cancer cells. The bone scaffold is immersed in a fluid flow inside a bioreactor. Cancer cells are seeded to grow on the surface of the scaffold for 23 days before being harvested for analysis.  Based on the micro-Computed Tomography scans from the in-vitro experiments, we created a full-scale 3D surface mesh of the scaffold using open-source software Slicer3D and Meshmixer. The computational grid was generated using the commercial software Gridgen Pointwise. We performed Computational Fluid Dynamics (CFD) simulations with the immersed boundary method to investigate the flow patterns inside the pores of the scaffolds. Post-processing of the results was carried out using the open-source software Paraview and Blender to provide a high-resolution visualization of the flow within the scaffold's complex porous geometry. The flow velocity and the shear stress distributions inside the scaffold are shown to be convoluted and very sensitive to the pore size. The computational results show a distinctive difference on the shear stress distribution on the scaffold's sides. Our results suggest that there is a link between interstitial flow patterns and cancer cell growth.