Standardized microfluidic assessment of red blood cell–mediated microcapillary occlusion: Association with clinical phenotype and hydroxyurea responsiveness in sickle cell disease

Abstract

Objectives We present a standardized in vitro microfluidic assay and Occlusion Index (OI) for the assessment of red blood cell (RBC)–mediated microcapillary occlusion and its clinical associations in sickle cell disease (SCD). Methods Red blood cell mediated microcapillary occlusion represented by OI and its clinical associations were assessed for seven subjects with hemoglobin‐SC disease (HbSC), 18 subjects with homozygous SCD (HbSS), and five control individuals (HbAA). Results We identified two sub‐populations with HbSS based on the OI distribution. HbSS subjects with relatively higher OIs had significantly lower hemoglobin levels, lower fetal hemoglobin (HbF) levels, and lower mean corpuscular volume (MCV), but significantly higher serum lactate dehydrogenase levels and absolute reticulocyte counts, compared to subjects with HbSS and lower OIs. HbSS subjects who had relatively higher OIs were more likely to have had a concomitant diagnosis of intrapulmonary shunting (IPS). Further, lower OI associated with hydroxyurea (HU) responsiveness in subjects with HbSS, as evidenced by significantly elevated HbF levels and MCV. Conclusions We demonstrated that RBC‐mediated microcapillary occlusion and OI associated with subject clinical phenotype and HU responsiveness in SCD. The presented standardized microfluidic assay may be useful for evaluating clinical phenotype and assessing therapeutic outcomes in SCD, including emerging targeted and curative treatments that aim to improve RBC deformability and microcirculatory health.

Normalization of Blood Viscosity According to the Hematocrit and the Shear Rate

“…These biomechanical properties have a fundamental contribution to blood viscosity. Furthermore, its has been mentioned that these properties are indicators of specific diseases related to RBCs and blood flow [ 43 , 44 , 45 , 46 , 47 , 48 ].…”

Metabolic Influences Modulating Erythrocyte Deformability and Eryptosis

“…After the RBCs were deformed under the influence of this shear stress, the dynamic RBC recovery was monitored and analyzed according to the Kelvin-Voigt model, allowing the measurement of an elastic shear modulus of RBCs submitted to different shear rates. Even more recently, another group [7][8][9] developed a microfluidic impedance red cell assay (MIRCA) in order to measure RBC transition through narrow openings and also challenged to some extent the concept of 'fluid drop-like' RBCs whose deformation was assumed to be mostly related to viscosity with little or no elastic component. The authors defined new parameters such as an RBC occlusion index (ROI) and an RBC electrical impedance index (REI), which measure the cumulative percentage of vessel occlusion and the impedance change, respectively.…”

Dynamic pH and Thermal Analysis of Paper-Based Microchip Electrophoresis

“…We have previously developed the first mass-producible, paper-based microchip electrophoresis (HemeChip) system for separation, identification, and quantification of various subtypes of hemoglobin variants for screening and diagnosing hemoglobin disorders (e.g., sickle cell disease) [7,[17][18][19][20][21][22][23]. Particularly in sickle cell disease (SCD), polymerization of hemoglobin S makes red blood cells stiff, which triggers abnormal cellular adhesion on inflamed vascular walls and the hallmark vaso-occlusive crisis [24][25][26][27][28]. HemeChip enables newborn/neonatal screening and, thus, early, comprehensive medical care to mitigate SCD-related complications.…”