Atomic force microscopy in the assessment of erythrocyte membrane mechanical properties with exposure to various physicochemical agents

Abstract

Background: Mechanical properties of cell membranes and their structural organization are considered among the most important biological parameters affecting the functional state of the cell. Under the influence of various pathogenic factors, erythrocyte membranes lose their elasticity. The resulting changes in their biomechanical characteristics is an important, but poorly studied topic. It is of interest to study the deformation of native erythrocytes to a depth compatible with their deformation in the bloodstream.Aim: To investigate the patterns of deep deformation and the particulars of structural organization of native erythrocyte membranes before and after their exposure to physicochemical agents in vitro.Materials and methods: Cell morphology, nanostructure characteristics, and membrane deformation of native erythrocytes in a  solution of hemoconservative CPD/SAGM were studied with atomic force microscope NTEGRA Prima. Hemin, zinc ions (Zn2+), and ultraviolet (UV) radiation were used as modifiers. To characterize the membrane stiffness, we measured the force curves F(h), hHz (the depth to which the probe immersion is described by interaction with a homogeneous medium), and the Young's modulus values of the erythrocyte membrane.Results: Exposure to hemin, Zn2+ and UV radiation led to transformation of the cell shape, appearance of topological defects and changes in mechanical characteristics of erythrocyte membranes. Under exposure to hemin, Young's modulus increased from 10±4  kPa to 27.2±8.6  kPa (p<0.001), exposure to Zn2+, to 21.4±8.7  kPa (p=0.002), and UV, to 18.8±5.6  kPa (p=0.001). The hHz value was 815±210  nm for the control image and decreased under exposure to hemin to 420±80 nm (p<0.001), Zn2+, to 370±90 nm (p<0.001), and UV, to 614±120 nm (p=0.001).Conclusion: The results obtained contribute to a  deeper understanding of interaction between membrane surfaces of native erythrocytes and small vessel walls. They can be useful in clinical medicine as additional characteristics for assessment of the quality of packed red blood cells, as well as serve as a basis for biophysical studies into the mechanisms of action of oxidative processes of various origins.