Even patients with mild COVID-19 symptoms after SARS-CoV-2 infection show prolonged altered red blood cell morphology and rheological parameters.

Infection with the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and the associated coronavirus disease-19 (COVID-19) might affect red blood cells (RBC); possibly altering oxygen supply. However, investigations of cell morphology and RBC rheological parameters during a mild disease course are lacking and thus, the aim of the study. Fifty individuals with mild COVID-19 disease process were tested after the acute phase of SARS-CoV-2 infection (37males/13 females), and the data were compared to n = 42 healthy controls (30 males/12 females). Analysis of venous blood samples, taken at rest, revealed a higher percentage of permanently elongated RBC and membrane extensions in COVID-19 patients. Haematological parameters and haemoglobin concentration, MCH and MCV in particular, were highly altered in COVID-19. RBC deformability and deformability under an osmotic gradient were significantly reduced in COVID-19 patients. Higher RBC-NOS activation was not capable to at least in part counteract these reductions. Impaired RBC deformability might also be related to morphological changes and/or increased oxidative state. RBC aggregation index remained unaffected. However, higher shear rates were necessary to balance the aggregation-disaggregation in COVID-19 patients which might be, among others, related to morphological changes. The data suggest prolonged modifications of the RBC system even during a mild COVID-19 disease course.

Interpretation of osmotic gradient ektacytometry (osmoscan) data: a comparative study for methodological standards.

Osmotic gradient ektacytometry (measuring elongation index in the function of osmolality at a constant shear stress) is a sensitive method to analyze red blood cell (RBC) deformability and investigating the optimal osmolality range for the cells in normal or pathophysiological cellular and micro-environmental conditions. However, the methodological conditions are different, since the results are influenced by the applied shear stress (SS). In this study we investigated rat, dog, pig and human blood samples at SS of 1, 2, 3, 5, 10, 20 and 30 Pa. To describe the range being related to the cell deformability, we introduced new calculated parameters obtained from the raw data of the elongation index (EI)-osmolality (O) curves. Our results showed that: (1) Osmoscan data tested at 20 or 30 Pa do not differ significantly from each other; (2) Under SS of 20 Pa the EImax, the O (EImax), the EI min and the area under curve nearly linearly decrease in the function of SS with different slope in rat, dog, pig and human blood; (3) Measurements under 3 Pa SS become unstable; (4) The differences between minimal and maximal EI and the belonging osmolality values, and their ratios, as new calculated parameters (ΔEI, ΔO, ΔEI/ΔO, EImax/EImin and O (EImax)/Omin) can be suitable for further analysis of the osmoscan curves together with other hemorheological parameters describing RBC deformability; and (5) Decreased erythrocyte deformability (by rigidifying with glutaraldehyde) can be reflected well with the following, calculated osmoscan parameters: ΔO, rO, rEI/rO and ΔEI/ΔO.

Osmotic gradient ektacytometry - a novel diagnostic approach for neuroacanthocytosis syndromes.

Introduction: The unique red blood cell (RBC) properties that characterize the rare neuroacanthocytosis syndromes (NAS) have prompted the exploration of osmotic gradient ektacytometry (Osmoscan) as a diagnostic tool for these disorders. In this exploratory study, we assessed if Osmoscans can discriminate NAS from other neurodegenerative diseases. Methods: A comprehensive assessment was conducted using Osmoscan on a diverse group of patients, including healthy controls (n = 9), neuroacanthocytosis syndrome patients (n = 6, 2 VPS13A and 4 XK disease), Parkinson's disease patients (n = 6), Huntington's disease patients (n = 5), and amyotrophic lateral sclerosis patients (n = 4). Concurrently, we collected and analyzed RBC indices and patients' characteristics. Results: Statistically significant changes were observed in NAS patients compared to healthy controls and other conditions, specifically in osmolality at minimal elongation index (Omin), maximal elongation index (EImax), the osmolality at half maximal elongation index in the hyperosmotic part of the curve (Ohyper), and the width of the curve close to the osmolality at maximal elongation index (Omax-width). Discussion: This study represents an initial exploration of RBC properties from NAS patients using osmotic gradient ektacytometry. While specific parameters exhibited differences, only Ohyper and Omax-width yielded 100% specificity for other neurodegenerative diseases. Moreover, unique correlations between Osmoscan parameters and RBC indices in NAS versus controls were identified, such as osmolality at maximal elongation index (Omax) vs. mean cellular hemoglobin content (MCH) and minimal elongation index (EImin) vs. red blood cell distribution width (RDW). Given the limited sample size, further studies are essential to establish diagnostic guidelines based on these findings.

Influence of age and sex on osmoscan indies for next-generation osmotic gradient ektacytometry.

BACKGROUND AND AIMS: Osmotic gradient ektacytometry is an important method for diagnosis of red blood cell membrane disorders. For interpretation of the osmoscan parameters on the ektacytomety, an age-matched control sample drawn at the same time is recommended for direct comparison. However, this can be challenging for laboratories to fulfil, especially when ektacytometry is performed in children. Therefore, the aim of this study was to evaluate the influence of age and sex on the osmoscan parameters. MATERIALS AND METHODS: Blood samples from 231 subjects were analyses on a LoRRca MaxSIS. Data were investigated for need of partitioning by age and sex. After outlier detection, reference intervals (RIs) for osmoscan parameters were estimated. RESULTS: For all parameters except EImin, lower values were observed in infants < 3 month (N = 50) than in all other age group. Hence, RIs were calculated separately for this age group. For EImin, a unified RI was calculated. No difference between sexes was observed for any of the parameters. CONCLUSION: Lower RIs and a left shift in the osmoscan curves were observed in infants < 3 months compared with older subjects. Hence, age-matched controls are necessary when evaluating ektacytometry in newborns, but can be ignored in older children and adults. This will ease the laboratory workflow when performing ektacytometry.

Interspecies Diversity of Osmotic Gradient Deformability of Red Blood Cells in Human and Seven Vertebrate Animal Species.

Plasma and blood osmolality values show interspecies differences and are strictly regulated. The effect of these factors also has an influence on microrheological parameters, such as red blood cell (RBC) deformability and aggregation. However, little is known about the interspecies differences in RBC deformability at various blood osmolality levels (osmotic gradient RBC deformability). Our aim was to conduct a descriptive-comparative study on RBC osmotic gradient deformability in several vertebrate species and human blood. Blood samples were taken from healthy volunteers, dogs, cats, pigs, sheep, rabbits, rats, and mice, to measure hematological parameters, as well as conventional and osmotic gradient RBC deformability. Analyzing the elongation index (EI)-osmolality curves, we found the highest maximal EI values (EI max) in human, dog, and rabbit samples. The lowest EI max values were seen in sheep and cat samples, in addition to a characteristic leftward shift of the elongation index-osmolality curves. We found significant differences in the hyperosmolar region. A correlation of mean corpuscular volume and mean corpuscular hemoglobin concentration with osmoscan parameters was found. Osmotic gradient deformability provides further information for better exploration of microrheological diversity between species and may help to better understand the alterations caused by osmolality changes in various disorders.

Comparative osmotic gradient ektacytometry data on inter-species differences of experimental animals.

It is known that red blood cell deformability may show colorful inter-species differences, influenced by inner viscosity, cell membrane viscosity, morphology and surface-volume ratio of the erythrocytes. It is also well-known that the cell volume is changing depending on the micro-environmental osmolarity. These changes can be well observable using osmotic gradient ektacytometry (osmoscan). Interestingly, there is a lack of base and comparative osmoscan data regarding the experimental/laboratory animal species. In this study mouse, rat, canine and porcine blood samples were analyzed using a LoRRca MaxSis Osmoscan ektacytometer. The highest elongation index values were found in mouse, typically above shear stress of 1 Pa. Some lower values than these were shown in rat and more lower in canine, while the lowest values were detected in porcine, typically above 3-5 Pa. The optimal osmolarity point value, so the measurable maximal EI osmolarity was in a wide range among the species. While the lowest values were detected in canine, the highest ones in porcine and mouse, the rat values were in between. Further analysis and wider comparison of the osmotic gradient ektacytometry may contribute to the better understanding of the erythrocyte micro-rheological properties, their induced changes and inter-species differences.

Effects of various drugs (flunixin, pentoxifylline, enoxaparin) modulating micro-rheological changes in cerulein-induced acute pancreatitis in the rat.

Previously we have investigated the cerulein-induced acute pancreatitis and provided data on its micro-rheological impact in the rat. We hypothesized that non-steroid anti-inflammatory agent flunixin, the xanthine-derivate pentoxifylline and the low molecular weight heparin enoxaparin may have various beneficial effects improving microcirculatory and rheological parameters. In female rats, under general anesthesia, 10 µg/kg cerulein s.c. was administered and 2 hours afterwards microcirculation was tested by laser Doppler flowmetry on the tongue and after performing laparotomy on the small intestine, liver and pancreas prior to terminal blood sampling. From blood samples hematological parameters, blood pH, lactate concentration, erythrocyte deformability, osmoscan parameters and erythrocyte aggregation were tested. Compared to normal control in acute pancreatitis group we found severe deterioration in tissue microcirculation together with impaired erythrocyte deformability and enhanced aggregation, accompanied by acidic pH and increasing lactate concentration. Improvement was found when using flunixin (s.c.), pentoxifylline (i.p.) or enoxaparin (s.c.). These drugs could partly improve the blood flux on the surface of the investigated organs, and the flunixin had the most expressed improving effects on micro-rheological parameters. Surprisingly, the improving effect of pentoxifylline on micro-rheological parameters was not obvious (red blood cell deformability did not improved better than in the other treated groups), however, microcirculatory parameters improved.