Computational modeling of biomechanical response of osteocyte integrin and cytoskeleton based on the piezoelectricity of bone matrix

Abstract

Osteocytes are key in bone remodeling, responding to mechanical stimuli. The piezoelectric bone matrix converts these stimuli into electrical signals, influencing remodeling. To delve deeper into this, we created an osteocyte model within a piezoelectric bone matrix, incorporating the lacuna-canalicular system and mechanosensors such as integrins, cytoskeleton, and primary cilia. Upon subjecting the bone matrix to triaxial dynamic displacement loads, we examined the electric potential and flow velocity distributions and analyzed the mechanical signals of six mechanosensors. The results show that the strain is greater when the bone matrix is piezoelectric than non-piezoelectric. The maximum average potential of the surface structure of the cell membrane is about 69.3 mV. Piezoelectricity significantly increases the fluid velocity and changes the trend. The cytoskeleton and integrins in cell process experience greater stress than in cell body. Microtubules experience greater stress than actin filaments. Among all integrins, those in contact with collagen hillocks experience the greatest stress. In individual integrin, the β subunit has higher stress than α subunit, and the stress of legs connected to cytoskeleton is higher than head contacted with fluid. Within the cytoplasm, the stress of integrin increases with a decrease of the surrounding cytoskeleton density. Moreover, collagen hillocks have the greatest fluid shear stress and stress. Integrins, primary cilia, and cytoskeleton all exhibit significant displacement signal amplification, especially integrins. In conclusion, this study illuminates the complex process of mechanosensing in osteocytes within a piezoelectric environment. The established model offers valuable insights into the mechanism of osteomechanical signal transduction.