Аннотация:BACKGROUND:
The novel measure of the red blood cells (RBC) aggregation (RBC-A) - the critical (minimum) shear stress (CSS) to prevent the cells from aggregation was found to be a promising clinically significant parameter. However, the absolute values of this parameter were found to change significantly depending on the shearing geometry (cup-and-bob, cone-plate or microchannel-flow) and have different temperature dependences along with it. The direct confirmation of these dependences aimed to find out the correct values is still pending.
OBJECTIVE:
In this work, we aim to assess the absolute values of CSS at different temperatures.
METHODS:
The single cell level measurements of CSS were performed using optical tweezers. The measurements were carried out in heavily diluted suspensions of RBCs in plasma.
RESULTS:
The temperature dependent changes in CSS were measured at the points (22 and 38°C), in which the cup-and-bob and cone-plate systems yielded about 1.5-fold different values, while the microchannel-flow system yielded a constant value. The single cell CSS were found to be 362±157 mPa (22°C) and 312±57 mPa (38°C).
CONCLUSIONS:
Our results prove that the microfluidic-flow approach is reflecting the RBC-A correctly. While the CSS values measured with other systems show the temperature dependent effect of the shearing geometry.
KEYWORDS:
Red blood cell; aggregation; critical shear stress; microfluidic flow; optical tweezers; shearing-geometry; single-cell level measurements; temperature