Finite element modeling of the micropipette aspiration of malaria-infected red blood cells

Abstract

Micropipette aspiration is one of the most widely used techniques for measuring the mechanical properties of single cells. The homogeneous linear elastic half-space model has been frequently applied to characterize the micropipette aspiration of chondrocytes and endothelial cells. However, the linear elastic model is limited to small deformation and the half-space assumption is frequently invalidated when moderately large micropipettes are used. In this work, the linear elastic constitutive model is extended to the neo-Hookean constitutive model and the geometry is simulated more realistically by considering the cell as a sphere. The large-deformation contact mechanics problem is solved using dimensionless axisymmetric finite element analysis. The effects of pipette diameter and fillet radius on the cellular rheological behaviour are also systematically studied. Based on the finite element simulation, empirical relationships have been derived for the direct interpretation of the elastic mechanical parameters from the micropipette aspiration experiments. Micropipette aspiration of late-stage malaria-infected red blood cells (schizonts) is conducted. The infected cells are found to exhibit elastic solid behavior in contrast to the liquid drop behavior of healthy red blood cells. The apparent shear modulus of the schizonts, interpreted from the elastic solid model, is found to be 119±62 Pa.