An experimental erythrocyte rigidity index (Ri) and its correlations with Transcranial Doppler velocities (TAMMV), Gosling Pulsatility Index PI, hematocrit, hemoglobin concentration and red cell distribution width (RDW)

Abstract

Brain artery velocities (Time-Averaged Maximum Mean Velocity, TAMMV) by Transcranial Doppler (TCD), hematocrit, hemoglobin, Red blood cell (RBC) Distribution Width (RDW) and RBC rigidity index (Ri), when reported together with their correlations, provide a accurate and useful diagnostic picture than blood viscosity measurements alone. Additionally, our study included a sixth parameter provided by TCD, the Gosling Pulsatility Index PI, which is an indicator of CBF (Cerebral Blood Flow) resistance. All these parameters are routine in Hematology except for values of Ri. The rigidity (Ri) of the RBC is the main rheological characteristic of the blood of Sickle Cell Anemia (SCA) patients and several pathologies. However, its quantification depends on many commercial and experimental techniques, none disseminated and predominant around the World. The difference in absorbance values of the blood, during the process of sedimentation in a microwell of a Microplate Reader, is a straightforward way of semi-quantifying the RBC rigidity Ri, since the fraction of irreversibly sickled red blood cells does not form rouleaux. Erythrocyte Rigidity Index (Ri) was calculated using initial absorbance A initial (6 s) and final A final (540 s), Ri = 1 / (Ai-Af). The Ri of 119 patients (2-17 y / o, M & F) SCA, SCC (Sickle Cell/hemoglobin C), SCD (Sickle Cell/hemoglobin D), Sβ0thal (Sickle Cell/hemoglobin Beta Zero Thalassemia) and 71 blood donors (20-65 y / o, M & F) were measured in our laboratory while the five parameters (TAMMV and PI by TCD, Hct, Hb and RDW) were obtained from medical records. The in vitro addition of hydroxyurea (HU, 50mg /dl, n = 51 patients, and n = 8 healthy donors) in the samples decreased the rouleaux adhesion strength of both donor and patients' blood samples, leading to extraordinarily high Ri values. The correlation between the studied parameters was especially significant for the direct relationships between Ri, TAMMV, and PI.

Preliminary Study of Genome-Wide Association Identified Novel Susceptibility Genes for Hemorheological Indexes in a Chinese Population

“…The rigidity of erythrocyte is the main rheological characteristic of the blood of Sickle Cell Anemia patients and several pathologies [38]. Three genome-level significant SNPs (rs11661911 in GTSCR1 - LINC01541 , rs1297329 in USP25 - MIR99AHG and rs28371438 in LOC102724502 - OLIG2 ) associated with erythrocyte rigidity index level were identified.…”

Using genetics to detangle the relationships between red cell distribution width and cardiovascular diseases: a unique role for body mass index

“…One is that both BMI and RDW have been linked to red blood rheology and rigidity. 31 32 Elevated BMI is known to induce changes in RBC flexibility, bone marrow adipocyte content, and erythropoietin signalling, all of which may affect RDW. 32 33 Additionally, BMI-associated chronic inflammation has been hypothesised to be a mechanistic link between BMI and RBC health; however, recent studies have detected no significant correlation between RDW and inflammatory markers in obese patients.…”

Biomechanical properties of endothelial glycocalyx: An imperfect pendulum

“…In this context it is conceivable that pathological conditions primarily affecting the rigidity of RBCs, such as sickle cell disease or invasion by Plasmodium falciparum , or use of blood after a long storage [41] , [42] ; all could affect the hovercraft-like movement of RBCs in the capillary bed. The confirmation of such a prediction is provided by the fact that stiff RBCs are prone to margination [43] .…”