Nano- and microscale mechanical properties of erythrocytes in hereditary spherocytosis.

Hereditary spherocytosis (HS), an erythrocyte membranopathy, is a heterogeneous disease, even at the level of the erythrocyte population. The paper aims at studying the mechanical properties (the Young's modulus, median and RMS roughness of friction force maps; fractal dimension, lacunarity and spatial distribution parameters of lateral force maps) of the cell surface layer of the erythrocytes of two different morphologies (discocytes and spherocytes) in HS using atomic force microscopy. The results of spatial-spectral and fractal analysis showed that the mechanical property maps of the HS spherocyte surface were more structurally homogeneous compared to the maps of HS discocytes. HS spherocytes also had a reduced RMS roughness and lacunarity of the mechanical property maps. The Young's modulus and averaged friction forces over the microscale HS spherocyte surface regions were approximately 20% higher than that of HS discocytes. The revealed significant difference at the nano- and microscales in the structural and mechanical properties of main (discoidal and spheroidal) morphological types of HS erythrocytes can potentially cause blood flow disturbance in the vascular system in HS.