Red blood cell mechanical stability test

Abstract

Red blood cells (RBC) are exposed to various levels of shear stress (SS) during their flow in the circulatory system, yet no significant damage occurs if their mechanical stability is not impaired. Alternatively, normal RBC may be damaged during flow in non-physiological environments and under extreme SS (e.g., extracorporeal circulation, ventricular assist devices). The shear-induced damage may result in hemolysis or in altered mechanical properties of RBC that, in turn, reduces the ability of RBC to withstand further damage by SS. An ektacytometer employing a Couette shearing system was used to apply SS at a constant level of 100 Pa for 300 seconds as a model of sub-hemolytic mechanical stress. The degree of cellular damage during and after the application was assessed by diffraction pattern analysis. The area of the diffraction pattern was found to correlate with the number of RBC in the sheared suspension. Monitoring the ellipse area during the application of gradually increasing SS provides the concentration of the remaining intact RBC and can therefore be used to estimate the hemolytic threshold as a measure of RBC mechanical stability. The hemolytic threshold determined after the mechanical stress application was found to be ∼150 Pa, while it was ∼250 Pa in the same samples before the SS application. Additionally, SS-elongation index curves recorded before and after the application of the sub-hemolytic SS significantly differed from each other, indicating the impairment in deformability following the mechanical stress. The Couette type ektacytometer can be used as a tool to assess the sub-hemolytic damage to RBC in testing the biomedical equipment.

Repetitive Supra‐Physiological Shear Stress Impairs Red Blood Cell Deformability and Induces Hemolysis

“…As such, impaired RBC deformability within this range of shear stress may contribute to hypoxia given that delivery of oxygen to active tissues requires RBCs to traverse capillaries that are substantially smaller in diameter than RBCs (i.e., ∼3–5 µM) . The present study builds upon the findings of Baskurt and Meiselman who observed a right‐shift in the EI‐shear stress curve following 300 s continuous exposure to supra‐physiological shear stress (i.e., 100 Pa). In contrast, given the decrease in EI (Fig.…”

“…Given that hemolysis leads to platelet activation, increased [pfHb] represents an early biomarker of hemo‐compatibility used in the evaluation of mechanical circulatory assist devices, including ventricular assist devices (VAD). Nevertheless, recent studies have demonstrated that RBC deformability is impaired following exposure to supra‐physiological, but sub‐hemolytic, shear stress . Consequently, hemo‐compatibility may be considered for devices that mechanically impact RBCs without inducing significant hemolysis.…”

“…Given the importance of RBC deformability for adequate tissue perfusion and cardiovascular health, shear‐mediated impairments of RBC deformability may represent a valuable index of hemo‐compatibility. However, the exposure durations utilized in previous studies were either much greater (i.e., 10 s) or less (i.e., 16 ms) than the in situ transit times through mechanical assist devices . Thus, the present study aimed to assess changes in RBC deformability and the extent of hemolysis following exposure to a standardized supra‐physiological shear stress protocol—well below the recognized “hemolytic threshold”—with a duty‐cycle representative of a VAD.…”

Oxidative Stress Increases Erythrocyte Sensitivity to Shear‐Mediated Damage

“…Given impairments in RBC deformability lead to detrimental functional implications, including the diminished regulation of microcirculatory blood flow and the precipitation of complete cell destruction (8,16), an index of RBC susceptibility to mechanical damage was expressed by calculating the differences in SS 1/2 :EI max relative to control measures (prior to shearing), as a percentage of the control value (22,24):…”

Novel Extracorporeal Dialysis Circuit to Improve the Removal Efficiency of High and Middle Molecular Weight Toxins

“…This enhancement will lead to better detoxification particularly for high and middle molecular weight toxins. As increasing the flow rate in the blood compartment is faced with several challenges such as hemolysis (18,19), in this study, only the influence of applying the recirculation flow in the dialysate compartment and increase in dialysate flow rate was evaluated. A typical in vitro hemodialysis circuit was constructed for this investigation.…”