Blood Rheological Characterization of β-Thalassemia Trait and Iron Deficiency Anemia Using Front Microrheometry

The purpose of this work is to develop a hematocrit-independent method for the detection of beta-thalassemia trait (β-TT) and iron deficiency anemia (IDA), through the rheological characterization of whole blood samples from different donors. The results obtained herein are the basis for the development of a front microrheometry point-of-care device for the diagnosis and clinical follow-up of β-TT patients suffering hematological diseases and alterations in the morphology of the red blood cell (RBC). The viscosity is calculated as a function of the mean front velocity by detecting the sample fluid-air interface advancing through a microfluidic channel. Different viscosity curves are obtained for healthy donors, β-TT and IDA samples. A mathematical model is introduced to compare samples of distinct hematocrit, classifying the viscosity curve patterns with respect to the health condition of blood. The viscosity of the fluid at certain shear rate values varies depending on several RBC factors such as shape and size, hemoglobin (Hb) content, membrane rigidity and hematocrit concentration. Blood and plasma from healthy donors are used as reference. To validate their potential clinical value as a diagnostic tool, the viscosity results are compared to those obtained by the gold-standard method for RBC deformability evaluation, the Laser-Optical Rotational Red Cell Analyzer (LoRRCA).LM-M and JF-T received funding from programs Doctorat Industrial (2018 DI 068) and (2018 DI 064) from AGAUR (Generalitat de Catalunya). EK receives funding from Institut Josep Carreras (IJC) under program Equality Plus, project number 2019-1-TR01-KA202-076789. TA acknowledges funding under grant numbers MTM2015-71509-C2-1-R and MDM-2014-0445. TA has been partially funded by the CERCA Program of the Generalitat de Catalunya. AH-M acknowledges funding under project FIS2016-78883-C2-1P, Ministerio de Ciencia e Innovacion (Spain) under project PID2019-106063GB-100 and AGAUR (Generalitat de Catalunya) under project 2017 SGR-1061. CT-S and AH-M acknowledge partial support from ANID/PCI (Chile) under project MEC80180021

Red cell ektacytometry in two patients with chronic hemolytic anemia and three new α-spectrin variants

Red blood cell (RBC) morphology is, in general, the key diagnostic feature for hereditary spherocytosis (HS) and hereditary elliptocytosis (HE). However, in hereditary pyropoikilocytosis (HPP), the severe clinical form of HE, the morphological diagnosis is difficult due to the presence of a RBC morphological picture characterized by a mixture of elliptocytes, spherocytes, tear-drop cells, and fragmented cells. This difficulty increases in new-borns and/or patients requiring frequent transfusions, making impossible the prediction of the disease course or its severity. Recently, it has been demonstrated that the measurement of osmotic gradient ektacytometry (OGE), using a laser-assisted optical rotational ektacytometer LoRRca (MaxSis, RR Mechatronics), allows a clear differentiation between HS and HE, where the truncated osmoscan curve reflects the inability of the already elliptical cells to deform further under shear stress in the face of hypotonicity. In HPP, however, the RBCs appear to have a significantly decreased ability to maintain deformability in these conditions, and the classical trapezoidal profile of HE is less evident or indistinguishable from HS. Here, two unrelated patients with hereditary hemolytic anemia (HHA) due to HPP and HS, respectively, are described with the joint inheritance of a complex set of five genetic defects. Two of these defects are novel alpha-spectrin gene (SPTA1) variants, one is a microdeletion that removes the entire SPTA1 gene, and two are well-known low-expression polymorphic alleles: α-LELY and α-LEPRA. In the HPP patient (ID1), with many circulating spherocytes, the interactions between the two SPTA1 gene variants may lead, in addition to an elongation defect (elliptocytes), to a loss of membrane stability and vesiculation (spherocytes), and RBCs appear to have a significantly decreased ability to maintain deformability in hypotonic conditions. Due to this, the classical trapezoidal profile of HE may become less evident or indistinguishable from HS. The second patient (ID2) was a classical severe form of HS with the presence of more than 20% of spherocytes and few pincered cells. The severity of clinical manifestation is due to the coinheritance of a microdeletion of chromosome 1 that removes the entire SPTA1 gene with a LEPRA SPTA1 variant in trans. The diagnostic interest of both observations is discussed.We are indebted to the European Commission for the Equality Plus (Erasmus +) Grant (Ref. 2019-1-TR01-KA202-076789