Red blood cell mechanics
- Mohandas Narla, DSc
Mohandas Narla, DSc
- Vice President for Research
- New York Blood Center
During its passage through the circulation, an erythrocyte that is 7 to 8 microns in diameter must elongate, tank tread, and otherwise deform to pass through 3 micron diameter capillaries and 1 micron wide and 0.5 micron thick endothelial slits in the red pulp of the spleen (picture 1). Thus, during its 120-day life span, the erythrocyte must undergo extensive passive deformation and must be mechanically stable to resist fragmentation [1,2].
Red cell deformability is influenced by three distinct cellular components [3,4]:
●Cell shape or cell geometry, which determines the ratio of cell surface area to cell volume (SA/V); higher values of SA/V facilitate deformation.
●Cytoplasmic viscosity, which is primarily regulated by the mean corpuscular hemoglobin concentration (MCHC) and is therefore influenced by alterations in cell volume.
●Membrane deformability and mechanical stability, which are regulated by multiple membrane properties, which include elastic shear modulus, bending modulus, and yield stress.
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- Discher DE, Winardi R, Schischmanoff PO, et al. Mechanochemistry of protein 4.1's spectrin-actin-binding domain: ternary complex interactions, membrane binding, network integration, structural strengthening. J Cell Biol 1995; 130:897.
- CELL SHAPE
- Alterations in the SA/V ratio
- - Experimental manipulation of the SA/V ratio
- - Clinical examples
- CYTOPLASMIC VISCOSITY
- MEMBRANE DEFORMABILITY AND STABILITY
- Membrane mechanical properties
- Failure of membrane deformability and stability
- Decreased SA/V ratio
- Increased SA/V ratio
- Increased cytoplasmic viscosity
- Red cell membrane properties