A particle dynamic model of red blood cell aggregation kinetics.

To elucidate the relationship between microscopic red blood cell (RBC) interactions and macroscopic rheological behavior, we propose a two-dimensional particle model capable of mimicking the main characteristics of RBC aggregation kinetics. The mechanical model of RBCs sheared in Couette flow is based on Newton law. We assumed a hydrodynamic force to move particles, a force to describe aggregation and an elasticity force. The role of molecular mass and concentration of neutral polymers on aggregation [Neu, B., and H. J. Meiselman. Biophys. J. 83:2482-2490, 2002] could be mimicked. Specifically, it was shown that for any shear rate (SR), the mean aggregate size (MAS) grew with time until it reached a constant value, which is consistent with in vitro experiments. It was also demonstrated that we could mimic the modal relationship between MAS and SR and the occurrence of maximum aggregation at about 0.1 s(-1). As anticipated, simulations indicated that an increase in aggregation force augmented MAS. Further, augmentation of the depletion layer thickness influenced MAS only for SR close to zero, which is a new finding. To conclude, our contribution reveals that the aggregation force intensity and SR influence the steady state MAS, and that the depletion and layer thickness affect the aggregation speed.