Combined finite element (FE) modeling and fluid shear experiment to determine the viscoelastic material properties of osteocytes

Osteocytes exhibit solid-like viscoelastic behavior in response to mechanical stresses. The goal of this study was to determine the viscoelastic properties of osteocytes using a combined finite element analysis (FE) modeling and experimental approach. The three-dimensional (3D) cell shape of the osteocyte under fluid flow was reconstructed using using a novel pseudo-3D microscopy technique. The cell shape was input into an ADINA fluid-structure FE software. The osteocyte was modeled using a linear and incompressible viscoelastic standard solid with a finite strain. The viscoelastic material parameters were determined by matching the predicted cell surface displacements with those measured experimentally. The instantaneous modulus of an osteocyte was 0.81 kPa and the equilibrium modulus was 0.11 kPa. The apparent viscosity were 0.85 kPa-s. The material properties measured in this study are comparable to the cell material properties reported in previous studies. This fluid-structure interaction cell model based on individual cell geometry may provide a novel technique to measure the viscoelastic properties of individual cells, as well as potential mechanisms of mechanical signal transduction.