A computational simulation for combined stimulations of fluid flow and mechanical vibration to mimic the osteocyte mechanical environment

Abstract

Osteocytes are the primary sensors of mechanical stimuli in bone which regulate activities of osteoblasts and osteoclasts. Experimental studies to quantify the mechanical environment surrounding bone cells are challenging, for the reason that the computational and theoretical approaches should consider both the solid and fluid environments of osteocytes to predict how these cells are stimulated in vivo. Osteocytes are elastic cellular structures that deform in response to the external fluid flow imposed by mechanical loading. In this study, an FSI model was created from an ideal osteocyte lacunar geometry. Due to the fact that during daily activities, the bone is mechanically loaded which causes the interstitial fluid flow in the lacunar-canalicular chamber of the osteocyte, the combination of vibrational stimulation and oscillatory fluid flow was used the osteocyte enclosed in the extracellular matrix. The results showed that the maximum strain occurs where the cell processes enter the lacuna. Also, the highest shear stress was observed in the canalicular part of the osteocyte. The amount of shear stress at frequency of 5 Hz and amplitude of 10 nm with considering the integrin and primary cilia receptors was 6.65 Pa. When integrins are also considered, the maximum shear stresses increase by about 25%. The simulation results showed that the maximum stress occurs at a frequency of 5 Hz and in the part of cellular processes. The stress and strain experienced by osteocytes also increase with increasing amplitude of vibration.