title: Characterization of shear stress preventing red blood cells aggregation at the individual cell level: The temperature dependence.
abstract: 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.
authors: Optoelectronics and Measurement Techniques, University of Oulu, Oulu, Finland.|Department of Physics, M. V. Lomonosov Moscow State University, Moscow, Russia.
authors: K
authors: K
authors: Lee
authors: Department of Physics, M. V. Lomonosov Moscow State University, Moscow, Russia.|International Laser Centre, M. V. Lomonosov Moscow State University, Moscow, Russia.
authors: A
authors: A
authors: Priezzhev
authors: School of Mechanical Engineering, Korea University, Seoul, Korea.
authors: S
authors: S
authors: Shin
authors: Optoelectronics and Measurement Techniques, University of Oulu, Oulu, Finland.|Faculty of Science & Technology, Jean Monnet University, Saint-Étienne, France.
authors: F
authors: F
authors: Yaya
authors: Optoelectronics and Measurement Techniques, University of Oulu, Oulu, Finland.
authors: I
authors: I
authors: Meglinski
mesh_terms: D004903:Erythrocyte Aggregation / Q000502:physiology*; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D013314:Stress, Mechanical; D013696:Temperature
keywords: Red blood cell; aggregation; critical shear stress; microfluidic flow; optical tweezers; shearing-geometry; single-cell level measurements; temperature