Mechanical properties of the human red blood cell membrane at -15 degrees C.
The most common method for measuring the mechanical behavior of the human red blood cell (RBC) membrane is micropipette aspiration, because it can be used to apply both a low uniaxial stress at a small part of the membrane or high two-axial stresses to the whole membrane [E.A. Evans, R.E. Waugh, Mechano-chemical study of red cell membrane structure in situ, in: Kroc Foundation Series, vol. 13, Erythrocyte Mechanics and Blood Flow, Alan R. Liss. Inc., New York, 1980, pp. 31-56 (Chapter 3); H.J. Meiselman, Measures of blood rheology and erythrocyte mechanics, in: Kroc Foundation Series, vol. 13, Erythrocyte Mechanics and Blood Flow, Alan R. Liss. Inc., New York, 1980, pp. 75-117 (Chapter 5)]. The elastic shear moduli and area changes of the human RBC published to date were calculated by means of this technique. However, a main drawback of the method is its impracticability at subzero temperatures. Experiments at below 0 degrees C are of interest because it is at these temperatures that RBC lysis occurs during freezing and thawing after cryopreservation, via a mechanism that may be mechanical. A method for circumventing this limitation is deforming the cell membranes by applying an electric ac field to a supercooled suspension. In a previous study, we applied this technique to human RBCs down to -15 degrees C [M. Krueger, F. Thom, Deformability and stability of erythrocytes in high-frequency electric fields down to subzero temperatures, Biophys. J. 73 (1997) 2653-2666]. In this technique, the electrical dimensions must be translated into those of mechanics. We provided a formula for these calculations, which demonstrated excellent concordance with known mechanical measurements at room temperature [F. Thom, H. Gollek, Calculation of mechanical properties of human red cells based on electrically induced deformation experiments, J. Electrostat. 64 (2006) 53-61]. Using this formula, we have now calculated the shear moduli and stress-strain diagram for our deformation experiments at -15 degrees C and present the results below.
Institute for Transfusion Medicine, Charité -Universitätsmedizin Berlin, Berlin, Germany. fritz.thom@charite.de
Fritz
F
Thom
D001703:Biophysics / Q000379:methods; D001809:Blood Viscosity; D003080:Cold Temperature; D015925:Cryopreservation / Q000379:methods; D055119:Elastic Modulus; D004548:Elasticity; D004574:Electromagnetic Fields; D004910:Erythrocyte Membrane / Q000502:physiology*; D004912:Erythrocytes / Q000166:cytology / Q000502:physiology; D006801:Humans; D008051:Lipid Bilayers; D013314:Stress, Mechanical; D013696:Temperature
D008051:Lipid Bilayers