Modeling the Effects of Interstitial Fluid Flow on a Single Osteocyte and Its Processes

Abstract

In order to understand the manner in which local changes in mechanical environment are translated into cellular activity underlying tissue level bone adaptation, there is a need to explore fluid flow regimes at small scales such as the osteocyte. Recent developments provide impetus to model periosteocytic flow using computational fluid dynamics. In building this model, the local effects of fluid flow on the osteocyte cell body and its processes were analyzed. For each model, fluid flow was induced via a pressure gradient, and the CFD calculated, based on the Navier-Stokes equations, the shear stress at the cell-fluid interface and radial stress, acting normal to the cell surface. Based on the model, the osteocyte cell body is exposed primarily to effects of hydrodynamic pressure and the cell processes are exposed primarily to shear and radial stress, with highest stress gradients at sites where the process and the cell body intersect and where two cell processes join at the gap junction. Hence, this model simulates subcellular effects of fluid flow and suggests, for the first time to our knowledge, major differences in modes of loading between the domain of the cell body and that of the cell process.