The Effect of the Kind of Attachment of Primary Cilium to Cell in Its Response to the Fluid Flow: A 3D Computational Simulation

The primary cilium is an organelle which occurs singly on nearly every cell in the vertebrate body. This organelle which extends out of the cell surface like an antenna is known as cell sensor which is able to sense mechanical and chemical stimuli applied to the cell. Upon flow of fluid over the cell surface, primary cilium bends and the surrounding membrane experiences strain resulting in activation of ion channels and transfer of calcium ions. Thus, primary cilium is able to transduce mechanical stimuli to ion signals and to make the cell somehow sense the surrounding fluid flow. In this study a novel model which accommodates for both pivoting and bending of cilium in response to the fluid flow was presented. In this 3D model primary cilium is attached to the cell using a thin elastic layer which is a kind of boundary condition. The domain of the cilium is modeled with linear elastic material and finite element method was used along with fluid-structure interaction teqniques to solve the fully coupled governing equations. The maximum stress obtained at the base of the cilium is between 10 to 50 kPa depending on the stiffness of the elastic layer. Results show that application of this boundary condition causes the maximum stress and strain to move from the inner parts of the ciliary base to the lateral parts of it. That is why this model is able to better explain the sensitivity of response of the primary cilium to mechanical stimuli.