Methodological aspects of oxygen gradient ektacytometry in sickle cell disease: Effects of sample storage on outcome parameters in distinct patient subgroups

Article type: Research Article

Authors: Boisson, Camille^{a; b; 1} | Rab, Minke A.E.^{c; d; 1} | Nader, Elie^{a; b} | Renoux, Céline^{a; b; e} | van Oirschot, Brigitte A.^c | Joly, Philippe^{a; b; e} | Fort, Romain^f | Stauffer, Emeric^g | van Beers, Eduard J.^d | Sheehan, Vivien A.^h | van Wijk, Richard^{c; 1} | Connes, Philippe^{a; b; 1; *}

Affiliations: [a] “Vascular Biology and Red Blood Cell” Team, Laboratory LIBM EA7424, University of Lyon 1, Lyon, France | [b] Laboratory of Excellence GR-Ex, Paris, France | [c] Central Diagnostic Laboratory - Research, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands | [d] Van Creveldkliniek,University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands | [e] Laboratory of Biochemistry and Molecular Biology, UF Biochemistry of Red Blood Cell Diseases, Est Center of Biology and Pathology, Hospices Civils de Lyon, Lyon, France | [f] Department of Internal Medicine, Hospices Civils de Lyon, Lyon, France | [g] Department of Functional Respiratory Investigations, Croix-Rousse Hospital, Hospices Civils de Lyon, Lyon, France | [h] Department of Pediatrics, Emory University, Atlanta, GA, USA

Correspondence: [*] Corresponding author: Philippe Connes, PhD, “Vascular Biology and Red Blood Cell” Team, Laboratory LIBM EA7424, University of Lyon 1, Lyon, France. E-mail: pconnes@yahoo.fr; philippe.connes@univ-lyon1.fr.

Note: [1] These authors contributed equally to this work.

Abstract: Sickle cell disease (SCD) is a genetic disorder characterized by the production of an abnormal hemoglobin (Hb), which, under deoxygenation, may polymerize and cause a mechanical distortion of red blood cell (RBC) into a crescent-like shape. Recently a method, using ektacytometry principle, has been developed to assess RBC deformability as a function of oxygen tension (pO2) and is called oxygen gradient ektacytometry (oxygenscan). However, standardization of this test is needed to properly assess the tendency of sickling of RBCs under deoxygenation and to allow comparisons between different laboratories. The study compared the oxygenscan responses during blood storage between distinct populations of SCD patients. Blood from 40 non-transfused homozygous SCD patients (HbSS), 16 chronically transfused HbSS patients, and 14 individuals with compound heterozygous hemoglobin SC disease (HbSC) at steady-state was collected in EDTA tubes. Measurements were performed within 4 hours after collection and after 24 hours of storage at 4°C. We showed that storage affected the minimum RBC deformability reached during deoxygenation (EImin) in both non-transfused HbSS and HbSC patients and the maximum RBC deformability (EImax) measured before deoxygenation (i.e., in normoxia) in the three groups. In contrast, the tendency of RBCs to sickle under deoxygenation (i.e., the point of sickling; PoS) remained rather stable between the two time of measurements. Collectively, since the time between blood sampling and analysis affects some key oxygen gradient ektacytometry-derived parameters we recommend that each laboratory performs oxygenscan measurements at a standardized time point.

Keywords: Oxygen gradient ektacytometry, sickle cell disease, red blood deformability, storage

DOI: 10.3233/CH-201037

Journal: Clinical Hemorheology and Microcirculation, vol. 77, no. 4, pp. 391-394, 2021