Quantifying Porosity-Linked Mechanical Behaviour of Renal Tubular Epithelial Cells by Poroviscoelastic Modelling and AFM Nanoindentation

Abstract

Understanding the permeability characteristics of renal tubular epithelial cells is essential for exploring the mechanobiological regulation of solute and fluid transport in kidney physiology. In this study, we investigated the depth-dependent mechanical properties of renal tubular epithelial cells using atomic force microscopy (AFM)-based nanoindentation in combination with finite element analysis (FEA). Two material models-viscoelastic (VE) and poroviscoelastic (PVE)-were applied to fit the force-relaxation response at various indentation depths. The PVE model demonstrated better fitting performance in capturing time- and depth-dependent behaviour within the tested indentation range, by incorporating the effects of fluid redistribution within the cytoplasm. Furthermore, we assessed the impact of cytochalasin D on the mechanical response of cells. Drug treatment led to a significant reduction in elastic modulus and an increase in hydraulic permeability, indicating a softening effect and enhanced fluid mobility associated with cytoskeletal disruption. These findings have important implications for renal reabsorption and secretion, where fine regulation of water and solute movement is vital. This work provides new insights into how mechanical cues modulate epithelial barrier function, contributing to a better understanding of renal physiology and potential dysfunction in renal disease.