Red cell filterability determined using the cell transit time analyzer (CTTA): effects of ATP depletion and changes in calcium concentration

Blood Rheology and Hemodynamics

Seminars in Thrombosis and Hemostasis (STH) celebrates 50 years of publishing in 2024. To celebrate this landmark event, STH is republishing some archival material. This manuscript represents the most highly cited paper ever published in STH. The original abstract follows.Blood is a two-phase suspension of formed elements (i.e., red blood cells [RBCs], white blood cells [WBCs], platelets) suspended in an aqueous solution of organic molecules, proteins, and salts called plasma. The apparent viscosity of blood depends on the existing shear forces (i.e., blood behaves as a non-Newtonian fluid) and is determined by hematocrit, plasma viscosity, RBC aggregation, and the mechanical properties of RBCs. RBCs are highly deformable, and this physical property significantly contributes to aiding blood flow both under bulk flow conditions and in the microcirculation. The tendency of RBCs to undergo reversible aggregation is an important determinant of apparent viscosity because the size of RBC aggregates is inversely proportional to the magnitude of shear forces; the aggregates are dispersed with increasing shear forces, then reform under low-flow or static conditions. RBC aggregation also affects the in vivo fluidity of blood, especially in the low-shear regions of the circulatory system. Blood rheology has been reported to be altered in various physiopathological processes: (1) Alterations of hematocrit significantly contribute to hemorheological variations in diseases and in certain extreme physiological conditions; (2) RBC deformability is sensitive to local and general homeostasis, with RBC deformability affected by alterations of the properties and associations of membrane skeletal proteins, the ratio of RBC membrane surface area to cell volume, cell morphology, and cytoplasmic viscosity. Such alterations may result from genetic disorders or may be induced by such factors as abnormal local tissue metabolism, oxidant stress, and activated leukocytes; and (3) RBC aggregation is mainly determined by plasma protein composition and surface properties of RBCs, with increased plasma concentrations of acute phase reactants in inflammatory disorders a common cause of increased RBC aggregation. In addition, RBC aggregation tendency can be modified by alterations of RBC surface properties because of RBC in vivo aging, oxygen-free radicals, or proteolytic enzymes. Impairment of blood fluidity may significantly affect tissue perfusion and result in functional deteriorations, especially if disease processes also disturb vascular properties.

Microfluidic electrical impedance assessment of red blood cell-mediated microvascular occlusion

Alterations in the deformability of red blood cells (RBCs), occurring in hemolytic blood disorders such as sickle cell disease (SCD), contribute to vaso-occlusion and disease pathophysiology. There are few functional in vitro assays for standardized assessment of RBC-mediated microvascular occlusion. Here, we present the design, fabrication, and clinical testing of the Microfluidic Impedance Red Cell Assay (MIRCA) with embedded capillary network-based micropillar arrays and integrated electrical impedance measurement electrodes to address this need. The micropillar arrays consist of microcapillaries ranging from 12 μm to 3 μm, with each array paired with two sputtered gold electrodes to measure the impedance change of the array before and after sample perfusion through the microfluidic device. We define RBC occlusion index (ROI) and RBC electrical impedance index (REI), which represent the cumulative percentage occlusion and cumulative percentage impedance change, respectively. We demonstrate the promise of MIRCA in two common red cell disorders, SCD and hereditary spherocytosis. We show that the electrical impedance measurement reflects the microvascular occlusion, where REI significantly correlates with ROI that is obtained via high-resolution microscopy imaging of the microcapillary arrays. Further, we show that RBC-mediated microvascular occlusion, represented by ROI and REI, associates with clinical treatment outcomes and correlates with in vivo hemolytic biomarkers, lactate dehydrogenase (LDH) level and absolute reticulocyte count (ARC) in SCD. Impedance measurement obviates the need for high-resolution imaging, enabling future translation of this technology for widespread access, portable and point-of-care use. Our findings suggest that the presented microfluidic design and the integrated electrical impedance measurement provide a reproducible functional test for standardized assessment of RBC-mediated microvascular occlusion. MIRCA and the newly defined REI may serve as an in vitro therapeutic efficacy benchmark for assessing the clinical outcome of emerging RBC-modifying targeted and curative therapies.

Red Blood Cell Dysfunction in Critical Illness

Oxygen (O2) delivery, which is fundamental to supporting patients with critical illness, is a function of blood O2 content and flow. This article reviews red blood cell (RBC) physiology and dysfunction relevant to disordered O2 delivery in the critically ill. Flow is the focus of O2 delivery regulation: O2 content is relatively fixed, whereas flow fluctuates greatly. Thus, blood flow volume and distribution vary to maintain coupling between O2 delivery and demand. This article reviews conventional RBC physiology influencing O2 delivery and introduces a paradigm for O2 delivery homeostasis based on coordinated gas transport and vascular signaling by RBCs.

Pentachlorophenol-induced cytotoxicity in human erythrocytes: enhanced generation of ROS and RNS, lowered antioxidant power, inhibition of glucose metabolism, and morphological changes

Pentachlorophenol (PCP) is a class 2B human carcinogen that is used as an insecticide, herbicide, and wood preservative. PCP is rapidly absorbed and enters the blood where it can interact with erythrocytes. We have examined the effect of PCP on human erythrocytes. Treatment of erythrocytes with PCP increased the intracellular generation of reactive oxygen and nitrogen species. It also increased lipid and protein oxidation accompanied by decrease in glutathione levels and total sulfhydryl content. The activities of all major antioxidant enzymes were altered. The antioxidant power was significantly impaired resulting in lower free radical quenching and metal reducing ability of the PCP-treated cells. PCP exposure also inhibited the activities of enzymes of glycolysis and pentose phosphate shunt, the two pathways of glucose metabolism in erythrocytes. Heme degradation was enhanced leading to the release of free iron. Incubation of erythrocytes with PCP caused significant cell lysis suggesting plasma membrane damage which was also evident from inhibition of bound enzymes. Scanning electron microscopy of erythrocytes confirmed these biochemical results and showed that PCP treatment converted the normal biconcave discoids to echinocytes and other irregularly shaped cells. Thus, PCP induces oxidative and nitrosative stress in erythrocytes, alters the enzymatic and nonenzymatic antioxidant defense systems, inhibits glucose metabolism, and causes significant modifications in cellular morphology.

Integrated automated particle tracking microfluidic enables high-throughput cell deformability cytometry for red cell disorders

Investigating individual red blood cells (RBCs) is critical to understanding hematologic diseases, as pathology often originates at the single-cell level. Many RBC disorders manifest in altered biophysical properties, such as deformability of RBCs. Due to limitations in current biophysical assays, there exists a need for high-throughput analysis of RBC deformability with single-cell resolution. To that end, we present a method that pairs a simple in vitro artificial microvasculature network system with an innovative MATLAB-based automated particle tracking program, allowing for high-throughput, single-cell deformability index (sDI) measurements of entire RBC populations. We apply our technology to quantify the sDI of RBCs from healthy volunteers, Sickle cell disease (SCD) patients, a transfusion-dependent beta thalassemia major patient, and in stored packed RBCs (pRBCs) that undergo storage lesion over 4 weeks. Moreover, our system can also measure cell size for each RBC, thereby enabling 2D analysis of cell deformability vs cell size with single cell resolution akin to flow cytometry. Our results demonstrate the clear existence of distinct biophysical RBC subpopulations with high interpatient variability in SCD as indicated by large magnitude skewness and kurtosis values of distribution, the "shifting" of sDI vs RBC size curves over transfusion cycles in beta thalassemia, and the appearance of low sDI RBC subpopulations within 4 days of pRBC storage. Overall, our system offers an inexpensive, convenient, and high-throughput method to gauge single RBC deformability and size for any RBC population and has the potential to aid in disease monitoring and transfusion guidelines for various RBC disorders.

Erythrocytes as a biological model for screening of xenobiotics toxicity

Erythrocytes are the main cells in circulation. They are devoid of internal membrane structures and easy to be isolated and handled providing a good model for different assays. Red blood cells (RBCs) plasma membrane is a multi-component structure that keeps the cell morphology, elasticity, flexibility and deformability. Alteration of membrane structure upon exposure to xenobiotics could induce various cellular abnormalities and releasing of intracellular components. Therefore the morphological changes and extracellular release of haemoglobin [hemolysis] and increased content of extracellular adenosine triphosphate (ATP) [as signs of membrane stability] could be used to evaluate the cytotoxic effects of various molecules. The nucleated RBCs from birds, fish and amphibians can be used to evaluate genotoxicity of different xenobiotics using comet, DNA fragmentation and micronucleus assays. The RBCs could undergo programmed cell death (eryptosis) in response to injury providing a useful model to analyze some mechanisms of toxicity that could be implicated in apoptosis of nucleated cells. Erythrocytes are vulnerable to peroxidation making it a good biological membrane model for analyzing the oxidative stress and lipid peroxidation of various xenobiotics. The RBCs contain a large number of enzymatic and non-enzymatic antioxidants. The changes of the RBCs antioxidant capacity could reflect the capability of xenobiotics to generate reactive oxygen species (ROS) resulting in oxidative damage of tissue. These criteria make RBCs a valuable in vitro model to evaluate the cytotoxicity of different natural or synthetic and organic or inorganic molecules by cellular damage measures.

Protection from oxidative damage using Bidens pilosa extracts in normal human erythrocytes

Bidens pilosa (B. pilosa) is well known in Taiwan as a traditional Chinese medicine. The purpose of this study was to evaluate the ability of both the ethanol (EtOH) and ethylacetate/ethanol (EA/EtOH) extracts from the whole B. pilosa plant, to protect normal human erythrocytes against oxidative damage in vitro. It was determined that the oxidative hemolysis and lipid/protein peroxidation of erythrocytes induced by the aqueous peroxyl radical [2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)] were suppressed by both EtOH (50-150 microg/ml) and EA/EtOH (25-75 microg/ml) extracts of B. pilosa in concentration- and time-dependent manners. B. pilosa extracts also prevented the decline of superoxide dismutase (SOD) activity and the depletion of cytosolic glutathione (GSH) and ATP in erythrocytes. These results imply that B. pilosa may have protective antioxidant properties.

Correlation between the physicochemical property of some nonsteroidal anti-inflammatory drugs and changes in adenosine triphosphate, glutathione and hemoglobin in rat erythrocytes

This study was conducted to explore the relationship between physicochemical property and toxic effectiveness using rat red blood cells (RBCs). The toxic effectiveness of acid nonsteroidal anti-inflammatory drugs (NSAIDs) was systemically examined by the depletion of intracorpuscular adenosine triphosphate (ATP), glutathione (GSH), and hemoglobin (Hb) at various doses, increased every 5 fmol/RBC. When the RBCs were incubated with NSAIDs, the drugs attained maximum levels within RBC, and the levels were then reduced. The ATP depletion seemed to be observed on the excretion of the drugs prior to the depletions of GSH and Hb. The physicochemical properties of NSAIDs were obtained from QMPRPlus, SMILES code, and CS ChemRaw Ultra. Correlation between their physicochemical properties and their doses for the depletions of ATP, GSH and Hb was performed in comparison with those of the membrane bound enzyme (MBE) inhibiting- and methemoglobin (MHb)-generating drugs. The ATP depletion by NSAIDs was correlated with the GSH depletion and intracorpuscular levels of the drugs, but not with the Hb depletion. The GSH depletion was correlated with the Hb depletion and participated in the lipophilicity of the drugs.

Comparative efficacy of Keishi-bukuryo-gan and pentoxifylline on RBC deformability in patients with "oketsu" syndrome

Keishi-bukuryo-gan (Gui-Zhi-Fu-Ling-Wan) (KBG) is one of the prescriptions in Japanese traditional medicine for improving the "oketsu" syndrome, so-called blood stasis syndrome. "Oketsu" syndrome is an important pathological conception in Japanese traditional medicine and often accompanies cerebro-vascular disorders. Previously, we were able to reveal a deterioration of RBC (Red blood cell) deformability and viscoelasticity in patients with "oketsu" syndrome. The purpose of the present study was to evaluate whether KBG has an effect on RBC deformability in comparison with pentoxifylline (PXF). The subjects were 30 male patients with multiple lacunar infarctions. Eighteen patients (44-79 yrs, mean +/- SD, 66.1 +/- 10.7 yrs) were treated with 12 g of KBG daily for 4 weeks (KBG group). Twelve patients (59-78 yrs, 70.7 +/- 6.4 yrs) were treated with 300 mg of PXF daily for 4 weeks (PXF group). Based on the "oketsu" score, the patients of each group were divided into two subgroups, a non-"oketsu" group ("oketsu" score 20 points or less) and an "oketsu" group ("oketsu" score 21 points or higher). KBG had significant effects on RBC deformability as evaluated by filtration method. KBG also significantly increased intracellular ATP content, as did PXF. Moreover, KBG was more effective for patients with a more severe "oketsu" state. However, PXF was effective only in patients with "oketsu" syndrome, who might have deteriorated RBC deformability. In conclusion, the effect of KBG on RBC deformability was by no means inferior to PXF.

Protection of oxidative damage by aqueous extract from Antrodia camphorata mycelia in normal human erythrocytes

Antrodia camphorata (A. camphorata) is well known in Taiwan as a traditional Chinese medicine. The purpose of this study was to evaluate the ability of aqueous extract from A. camphorata mycelia to protect normal human erythrocytes against oxidative damage in vitro. Oxidative hemolysis and lipid/protein peroxidation of erythrocytes induced by the aqueous peroxyl radical [2,2'-Azobis(2-amidinopropane) dihydrochloride, AAPH] were suppressed by A. camphorata mycelia in a time-and concentration-dependent manner. A. camphorata mycelia also prevented the depletion of cytosolic antioxidant glutathione (GSH) and ATP in erythrocytes. Moreover, cultured human endothelial cell damage induced by AAPH was suppressed by A. camphorata mycelia. Interestingly, A. camphorata mycelia exhibited significant cytotoxicity against leukemia HL-60 cells but not against cultured human endothelial cells. These results imply that A. camphorata mycelia may have protective antioxidant and anticancer properties.

Diaspirin cross-linked hemoglobin improves oxygen extraction capabilities in endotoxic shock

We studied the effects of diaspirin cross-linked hemoglobin (DCLHb), a cell-free hemoglobin derived from human erythrocytes, on blood flow distribution and tissue oxygen extraction capabilities in endotoxic shock. Eighteen pentobarbital sodium-anesthetized, mechanically ventilated dogs received 2 mg/kg of E. coli endotoxin, followed by saline resuscitation to restore cardiac filling pressures to baseline levels. The animals were randomly divided into three groups: six served as control, six received DCLHb at a dose of 500 mg/kg (group 1) and six DCLHb at a dose of 1,000 mg/kg (group 2). Cardiac tamponade was then induced by saline injection in the pericardial sac to progressively reduce cardiac index and thereby allow study of tissue oxygen extraction capabilities. DCLHb had a dose-dependent vasopressor effect but did not significantly alter cardiac index or regional blood flow. During cardiac tamponade, critical oxygen delivery was 12.8 +/- 0.7 ml. kg(-1). min(-1) in the control group, but 8.6 +/- 0.9 and 8.2 +/- 0.7 ml. kg(-1). min(-1) in groups 1 and 2, respectively (both P < 0.05 vs. control group). The critical oxygen extraction ratio was 39.1 +/- 3.1% in the control group but 58.7 +/- 12.8% and 60.2 +/- 9.0% in groups 1 and 2, respectively. We conclude that DCLHb can improve whole body oxygen extraction capabilities during endotoxic shock in dogs.

Effect of stobadine on carbon tetrachloride-induced erythrocyte membrane changes in rats

Our previous study showed that stobadine is effective against ischemia/reperfusion-induced gastric mucosal injury. The present study examined the ability of stobadine to protect erythrocyte membrane against free radical injury after long-term carbon tetrachloride (CCl4) application. The erythrocyte membrane changes were established using colloid-osmotic hemolysis. The significant increase of colloid-osmotic hemolysis was found in animals treated with CCl4. CCl4 also increased formation of thiobarbituric acid-reactive substances (TBARs) and decreased thiol group content. Stobadine in both doses (10.0 and 20.0 mg.kg-1) protected erythrocyte membrane against CCl4-induced injury. The membrane lipid bilayer is the most affected part of the erythrocyte membrane. In presence of stobadine, CCl4-induced lipid peroxidation was partially or totally prevented whereas the level of total membrane thiols was increased. Based on these results, it can be concluded that protective effect of stobadine on CCl4-induced erythrocyte membrane changes should be related to its antioxidant properties.

Evidence that cell surface charge reduction modifes capillary red cell velocity-flux relationships in hamster cremaster muscle

1. From capillary red cell velocity (V)-flux (F) relationships of hamster cremaster muscle a yield velocity (VF = 0) can be derived at which red cell flux is zero. Red cell velocity becomes intermittent and/or red blood cells come to a complete standstill for velocities close to this yield velocity, and, at the same time, capillary tube haematocrit becomes very low. 2. We have tested whether the net negative charge of red blood cells (RBCs) contributes to the magnitude of VF = 0. Velocity-flux relationships were measured for normal cells, normal cells labelled with the fluorescent dye calcein (LRBCs), and red cells treated with hexadimethrine to mask negative charge and labelled with calcein as well (HDM-LRBCs). Measurements were done in a hamster cremaster muscle preparation applying video in vivo microscopy. 3. Hexadimethrine treatment reduced the net negative surface charge of red cells to 20% of control as estimated from transmission electron microscopy using a ferritin tagging technique. The values of VF = 0 found for normal red cells and HDM-LRBCs were 86 +/- 15 and 31 +/- 17 microns s-1, +/- S.E.M., n = 12, respectively, which were significantly different (P < 0.05). For normal cells and cells labelled with calcein only, VF = 0 values were 63 +/- 14 and 65 +/- 13 microns s-1, n = 8, respectively, which were not significantly different. The effect of HDM treatment did not alter filterability of the red cells as estimated from transit times through 5 microns pores. 4. The present findings demonstrate that the net negative charge of RBCs contributes significantly to the yield velocity for red blood cells entering capillaries and flowing through them. HDM treatment reduced the net negative charge of red blood cells and may have caused cells to enter capillaries more easily owing to reduced electrostatic repulsion at the capillary entrance. In addition, HDM treatment may have lowered intracapillary flow resistance by a reduction in electrostatic repulsive forces between red blood cells and negatively charged (macromolecules on) capillary endothelial cells at sites of irregular capillary cross-sectional shape, without significantly affecting the lubricating properties of the capillary endothelial glycocalyx and/or associated plasma macromolecules.

The effect of increasing temperature on skin blood flow and red cell deformability

Using laser Doppler techniques in nine healthy volunteers, we contrasted the effect of increasing local skin temperature at the elbow, a skin site with nutritive microvasculature, and the finger pulp, with predominantly arteriovenous anastomic (AVA) perfusion). We also assessed flow at the finger dorsum, with contributions of both types of microvasculature. In parallel with the laser Doppler studies, we determined the effect of increasing temperature on the red cell deformability of our subjects, using the new technique of Cell Transit Time Analysis (CTTA). Thermal stimulation produced very large increases in skin blood flow at all three sites tested. However, the magnitude and the pattern of increase were different at the three sites. At the finger pulp, there was a linear approximately threefold increase in flow as temperature increased from the basal level to 44 degrees C. At the elbow, basal flow was considerably lower than at the finger pulp and increased very slowly until skin temperature reached 38 degrees C. From that point, flow increased sharply, reaching tenfold the basal level at 44 degrees C. The thermally induced increase at the finger dorsum was intermediate between the other two sites, with a pattern resembling the elbow more than the finger pulp. These differences among the sites were attributable to substantially different patterns of change in the two components of flow, microvascular volume and velocity. At the finger pulp, there was very little increase in microvascular volume with increasing temperature. The curve was practically flat from basal temperature to 44 degrees C. In contrast, there was a linear increase in red blood cell velocity of about 300%. At the elbow, both microvascular volume and red blood cell velocity exhibited a parallel curvilinear pattern of equivalent increase, on the order of 300% for each. There was only a small increase in both parameters until the temperature reached 38 degrees, at which point there was a sharp increase in both. At the finger dorsum, the situation was intermediate, again resembling the elbow more than the finger pulp. Cell Transit Time Analysis revealed a progressive decrease in red cell transit time (TT), from 3.28 ms at 28 degrees C to 2.48 m at 44 degrees C, an overall change of 24%. The decrease in TT was accompanied by an increase in transit frequency, measured as counts s-1 (C s-1), from 3.1 to 5.3, an overall change of 71%. The changes in both TT and C/S were essentially linear.(ABSTRACT TRUNCATED AT 400 WORDS)