Abstract
In the blood flow through microvessels, platelets show high concentrations near the vessel wall. This phenomenon is called margination of platelets and is closely associated with hemostasis and thrombosis. In the present study, we conducted in vitro experiments using platelet-sized fluorescent particles as platelet substitutes to investigate the cross-sectional distribution of these particles in the red blood cell suspension flowing through microchannels with a square cross section. Fluorescence observations were performed to measure the transverse distribution of particles at various heights from the bottom face with the use of a confocal laser scanning microscope system. In downstream cross sections of the channel, particles showed focusing near the four corners rather than uniform margination along the entire circumference of the cross section. The focusing of particles near the corners was more enhanced for higher hematocrits. On the other hand, particles in circular channel flows showed nearly axisymmetric uniform accumulation adjacent to the channel wall. The present result suggests that the segregation of suspended particles in the flow of multicomponent suspensions could have such heterogeneous 2D features of particle distribution in the cross section of channels, especially for rectangular channels often used in microfluidics.
Highlights
Platelets in the microvasculature are known to show preferential concentration near the vessel wall, which is called “margination” or “near-wall excess” [1,2]
Red blood cells (RBCs) tend to move away from the vessel wall due to the lift force generated by their deformability, so that a thin layer, called the cell-free layer (CFL), is formed in the vicinity of the vessel wall that is depleted of RBCs [3]
In vitro studies showed that the platelet margination occurs only when RBCs are present [7]
Summary
Platelets in the microvasculature are known to show preferential concentration near the vessel wall, which is called “margination” or “near-wall excess” [1,2]. Micromachines 2021, 12, 1175 found in the experiments were well reproduced by numerical simulations, and it was elucidated that platelets in the RBC core are expelled toward the vessel wall by their random hydrodynamic interactions with surrounding RBCs under the influence of shear as well as volume exclusion, resulting in a high concentration of platelets in the CFL [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28] Most of these previous studies on the margination of platelets or platelet-sized particles in the RBC suspension flow have concerned circular channels [10,17,18,23,26,28] or rectangular channels with large aspect ratios [7,8,9,11].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
