Red blood cell rheology during a complete blood count: A proof of concept

Abstract

Counting and sizing blood cells in hematological analyzers is achieved using the Coulter principle. The cells flow in a micro-aperture in which a strong electrical field is imposed, so that an electrical perturbation, called pulse, is measured each time a cell crosses the orifice. The pulses are expected to contain information on the shape and deformability of Red Blood Cells (RBCs), since recent studies state that RBCs rotate and deform in the micro-orifice. By implementing a dedicated numerical model, the present study sheds light on a variety of cells dynamics, which leads to different associated pulse signatures. Furthermore, simulations provide new insights on how RBCs shapes and mechanical properties affect the measured signals. Those numerical observations are confirmed by experimental assays. Finally, specific features are introduced for assessing the most relevant characteristics from the various pulse signatures and shown to highlight RBCs alterations induced by drugs. In summary, this study paves the way to a characterization of RBC rheology by routine hematological instruments.

New erythrocyte parameters derived from the Coulter principle relate with red blood cell properties—A pilot study in diabetes mellitus

“…As reported before from in vitro data [ 3 ], the deformability of RBC might participate to some extent to the differences observed between the two groups but still to be characterized. Indeed, one can’t confirm that RBC deformability is the dominating determinant of such changes until a proper correlation study is performed to strictly compare these parameters to ektacytometry, considered as the gold standard method to assess RBC deformability.…”

“…Parameters and characterize the rotation dynamics of the cell and are closely related to its trajectory in the aperture. Varying RBC properties in physiological ranges have shown negligible effects on the trajectory but found to modify the pulse shape [ 3 ]. We though that these changes result in variations in and , since they derive from the signal.…”

“…In addition, samples were analyzed with a mock-up derived from the ABX Micros 60 (HORIBA Medical), for the recording of the electrical pulses induced by RBC in an aperture-electrode system (also called Coulter-based system). The pulses acquisition is performed by a LabVIEW ™ (National Instruments) code, as presented before [ 3 , 4 ]. The mock-up differs from the commercial version ABX Micros 60, with an electronic bandwidth increased to 150 kHz.…”

“…The original parameters are based on quantities and . As a reminder, the metric detects whether a rotation-associated peak is present on the pulse, while assesses the moment at which the rotation, and thus the peak, occurs [ 3 ]. Let consider a curve representing an electrical pulse: denotes the pulse maximum, while (T 1 -T 0 ) refers to the pulse width ( Fig 1a ).…”

“…While signals induced by near-wall trajectories are unsuitable for sizing the cells, they may contain additional information on the latter. In a recent study, we showed that parameters derived from such signals are related to the shape and deformability of in vitro drug-treated red blood cells (RBC) [ 3 ]. Briefly, next to the micro-orifice walls, high velocity shears induce cells to rotate.…”