Topological Structures and Membrane Nanostructures of Erythrocytes after Splenectomy in Hereditary Spherocytosis Patients via Atomic Force Microscopy

Characterizing morphological alterations in blood related disorders through Atomic Force Microscopy

Atomic Force Microscopy (AFM) is a very flexible method that can create topographical images from a range of materials and image surfaces. Significantly, AFM has emerged as an invaluable tool for dissecting the morphology and biochemical aspects of body cells and tissues. The high-resolution imaging capabilities of AFM enable researchers to discern alterations in cell morphology and understand the underlying mechanisms of diseases. It contributes to understanding disease etiology and progression. In the context of this review, our focus will be directed towards elucidating the pivotal role of AFM in analysis of blood related disorders. Through detailed comparisons with normal cells, we delve into the alterations in size, shape, and surface characteristics induced by conditions such as cancer, diabetes, anaemia, and infections caused by pathogens. In essence, various work described in this article highlights to bridge the gap between traditional microscopy and in-depth analysis of blood-related pathologies, which in turn offers valuable perspectives for both research and clinical applications in the field.

Splenectomy improves erythrocyte functionality in spherocytosis based on septin abundance, but not maturation defects

Splenectomy improves the clinical parameters of patients with hereditary spherocytosis, but its potential benefit to red blood cell (RBC) functionality and the mechanism behind this benefit remain largely overlooked. Here, we compared 7 nonsplenectomized and 13 splenectomized patients with mutations in the β-spectrin or the ankyrin gene. We showed that hematological parameters, spherocyte abundance, osmotic fragility, intracellular calcium, and extracellular vesicle release were largely but not completely restored by splenectomy, whereas cryohemolysis was not. Affected RBCs exhibited decreases in β-spectrin and/or ankyrin contents and slight alterations in spectrin membrane distribution, depending on the mutation. These modifications were found in both splenectomized and nonsplenectomized patients and poorly correlated with RBC functionality alteration, suggesting additional impairments. Accordingly, we found an increased abundance of septins, small guanosine triphosphate-binding cytoskeletal proteins. Septins-2, -7, and -8 but not -11 were less abundant upon splenectomy and correlated with the disease severity. Septin-2 membrane association was confirmed by immunolabeling. Except for cryohemolysis, all parameters of RBC morphology and functionality correlated with septin abundance. The increased septin content might result from RBC maturation defects, as evidenced by (1) the decreased protein 4.2 and Rh-associated glycoprotein content in all patient RBCs, (2) increased endoplasmic reticulum remnants and endocytosis proteins in nonsplenectomized patients, and (3) increased lysosomal and mitochondrial remnants in splenectomized patients. Our study paves the way for a better understanding of the involvement of septins in RBC membrane biophysical properties. In addition, the lack of restoration of septin-independent cryohemolysis by splenectomy may call into question its recommendation in specific cases.

New Insights into Hemolytic Anemias: Ultrastructural and Nanomechanical Investigation of Red Blood Cells Showed Early Morphological Changes

Several diseases are characterized by changes in the mechanical properties of erythrocytes. Hemolytic anemias are an example of these diseases. Among the hemolytic anemias, Sickle Cell Disease and Thalassemia are the most common, characterized by alterations in the structure of their hemoglobin. Sickle cell disease has a pathological origin in synthesizing abnormal hemoglobin, HbS. In contrast, thalassemia results in extinction or decreased synthesis of α and β hemoglobin chains. This work presents a detailed study of biophysical and ultrastructural early erythrocytes membrane alterations at the nanoscale using Atomic Force Microscopy (AFM). Cells from individuals with sickle cell anemia and thalassemia mutations were studied. The analysis methodology in the AFM was given by blood smear and exposure of the inner membrane for ghost analysis. A robust statistic was used with 65,536 force curves for each map, ten cells of each type, with three individuals for each sample group. The results showed significant differences in cell rigidity, adhesion, volume, and roughness at early morphological alterations, bringing new perspectives for understanding pathogenesis. The sickle cell trait (HbAS) results stand out. Significant alterations were observed in the membrane properties, bringing new perspectives for the knowledge of this mutation. This work presents ultrastructural and biomechanical signatures of sickle cell anemia and thalassemia genotypes, which may help determine a more accurate biophysical description and clinical prognosis for these diseases.

Ektacytometry Analysis of Post-splenectomy Red Blood Cell Properties Identifies Cell Membrane Stability Test as a Novel Biomarker of Membrane Health in Hereditary Spherocytosis

Hereditary spherocytosis (HS) is the most common form of hereditary chronic hemolytic anemia. It is caused by mutations in red blood cell (RBC) membrane and cytoskeletal proteins, which compromise membrane integrity, leading to vesiculation. Eventually, this leads to entrapment of poorly deformable spherocytes in the spleen. Splenectomy is a procedure often performed in HS. The clinical benefit results from removing the primary site of destruction, thereby improving RBC survival. But whether changes in RBC properties contribute to the clinical benefit of splenectomy is unknown. In this study we used ektacytometry to investigate the longitudinal effects of splenectomy on RBC properties in five well-characterized HS patients at four different time points and in a case-control cohort of 26 HS patients. Osmotic gradient ektacytometry showed that splenectomy resulted in improved intracellular viscosity (hydration state) whereas total surface area and surface-to-volume ratio remained essentially unchanged. The cell membrane stability test (CMST), which assesses the in vitro response to shear stress, showed that after splenectomy, HS RBCs had partly regained the ability to shed membrane, a property of healthy RBCs, which was confirmed in the case-control cohort. In particular the CMST holds promise as a novel biomarker in HS that reflects RBC membrane health and may be used to asses treatment response in HS.

Protective effect of syringic acid via restoring cells biomechanics and organelle structure in human lens epithelial cells

We have previously reported that syringic acid (SA) extracted from D. aurantiacum var. denneanum (kerr) may be used to prevent diabetic cataract (DC). However, the underlying mechanisms through which SA prevents DC in human lens epithelial cells (HLECs) remained unclear. In the present study, we employed single-molecule optics technologies, including transmission electron microscopy (TEM), atomic force microscopy (AFM), laser scanning confocal microscopy (LSCM) and Raman spectroscopy, to monitor the effect of SA on HLECs biomechanics and organelle structure in real-time. TEM suggested that SA improved the ultrastructure of HLECs with regard to nuclear chromatin condensation and reducing mitochondrial swelling and degeneration, which may aid in the maintenance of HLECs integrity in the presence of glucose. AFM revealed a reduced surface roughness and stiffness following SA treatment, suggesting an improved viscoelasticity of HELCs. Raman spectrometry and LSCM further revealed that these changes were related to a modification of cell liquidity and cytoskeletal structure by SA. Taken together, these results provide insights into the effects of SA on the biomechanics of HLECs and further strengthen the evidence for its potential use as a novel therapeutic strategy for DC prevention.

Nano-scientific Application of Atomic Force Microscopy in Pathology: from Molecules to Tissues

The advantages of atomic force microscopy (AFM) in biological research are its high imaging resolution, sensitivity, and ability to operate in physiological conditions. Over the past decades, rigorous studies have been performed to determine the potential applications of AFM techniques in disease diagnosis and prognosis. Many pathological conditions are accompanied by alterations in the morphology, adhesion properties, mechanical compliances, and molecular composition of cells and tissues. The accurate determination of such alterations can be utilized as a diagnostic and prognostic marker. Alteration in cell morphology represents changes in cell structure and membrane proteins induced by pathologic progression of diseases. Mechanical compliances are also modulated by the active rearrangements of cytoskeleton or extracellular matrix triggered by disease pathogenesis. In addition, adhesion is a critical step in the progression of many diseases including infectious and neurodegenerative diseases. Recent advances in AFM techniques have demonstrated their ability to obtain molecular composition as well as topographic information. The quantitative characterization of molecular alteration in biological specimens in terms of disease progression provides a new avenue to understand the underlying mechanisms of disease onset and progression. In this review, we have highlighted the application of diverse AFM techniques in pathological investigations.

The effect of splenectomy on complement regulatory proteins in erythrocytes in β-thalassemia major

INTRODUCTION

Hemolysis due to ineffective erythropoiesis is a serious problem β-thalassemia major (β-TM) patients. The role of complement system in the etiopathogenesis of hemolysis observed in β-TM were released. Hemolysis induced by activation of complement system is prevented by complement regulatory proteins. Decay accelerating factor (CD55), membrane inhibitor of reactive lysis (CD59), and complement reception 1 (CR1, CD35) are among these proteins. The absence of these proteins thus accounts for the increased susceptibility of erythrocytes to complement lysis. Splenomegaly and hypersplenism are common complications among thalassemia major patients necessitating splenectomy.

MATERIAL AND METHODS

In this study we investigated how splenectomy effects complement regulatory system in erythrocytes. We analysed CD35, CD55, and CD59 levels on erythrocytes in β-TM by flow cytometry.

RESULTS

The overall mean percentage of CD55 and CD35 positive RBCs of group 1 (22 β-TM with splenectomy) was significantly lower than group 2 (23 β-TM without splenectomy) and group 3 (healthy controls) (p < 0.05). The overall mean percentage CD59 positive RBCs of patients was no significantly different in all groups. The levels of CD35 and CD55 expression on the erythrocytes of splenectomized patients was significantly lower than non-splenectomized patients (p < 0.05).

CONCLUSIONS

Increased erythrocyte destruction and iron deposition in organs due to deficiency of these regulatory proteins may be the underlying mechanism of organ damage developing in β-TM patients.

Synergistic Integration of Laboratory and Numerical Approaches in Studies of the Biomechanics of Diseased Red Blood Cells

In red blood cell (RBC) disorders, such as sickle cell disease, hereditary spherocytosis, and diabetes, alterations to the size and shape of RBCs due to either mutations of RBC proteins or changes to the extracellular environment, lead to compromised cell deformability, impaired cell stability, and increased propensity to aggregate. Numerous laboratory approaches have been implemented to elucidate the pathogenesis of RBC disorders. Concurrently, computational RBC models have been developed to simulate the dynamics of RBCs under physiological and pathological conditions. In this work, we review recent laboratory and computational studies of disordered RBCs. Distinguished from previous reviews, we emphasize how experimental techniques and computational modeling can be synergically integrated to improve the understanding of the pathophysiology of hematological disorders.

Ultrastructural changes in red blood cells in aortic dissection patients under extracorporeal circulation: Atomic force microscopy study

PURPOSE

During extracorporeal circulation in heart surgery, blood is exposed to non-physiological conditions, such as high shear stress, foreign surfaces, turbulence, and hypothermia. These factors cause damage to the red blood cells, which is manifested by immediate and delayed hemolysis or some changes in the mechanical properties of red blood cells, defined as sublethal trauma. Unfortunately, sublethal trauma is hard to detect, and there is not enough morphological evidence regarding red blood cell sublethal trauma. In this study, red blood cell sublethal trauma was observed after extracorporeal circulation by describing ultrastructural changes in red blood cell membranes using atomic force microscopy and scanning electron microscopy.

METHODS

Venous blood (2 mL) was collected into heparin tubes from preoperative, intraoperative and postoperative aortic dissection patients for comparison with blood from healthy patients. The red blood cell morphological study (malformations percentage, diameter, height, concavity, and roughness) was performed with scanning electron microscopy and atomic force microscopy.

RESULTS

Scanning electron microscopy and atomic force microscopy imaging analysis revealed that the red blood cell shape changed during extracorporeal circulation and that the red blood cell malformation percentage in the postoperative group was higher than those in the preoperative and intraoperative groups. Most morphological parameters had no obvious changes, except roughness (Ra and Rq) in aortic dissection patients. Atomic force microscopy quantitative analysis indicated that the roughness of red blood cell membranes increased during extracorporeal circulation.

CONCLUSIONS

This study demonstrates that ultrastructural morphological damage occurs to red blood cells membranes due to extracorporeal circulation in aortic dissection patients. In addition, we provided a new parameter (Ra and Rq) to evaluate red blood cell sublethal trauma.

The effect of ozone on hypoxia, hemolysis and morphological change of blood from patients with aortic dissection (AD): a preliminary in vitro experiment of ozonated autohemotherapy for treating AD

This study aimed to investigate the effect of ozone on hypoxia, hemolysis and morphological change of blood from aortic dissection (AD) patients for providing preliminary evidence of application of ozonated autohemotherapy (Ozone-AHT) in AD patients. 20 AD patients and 20 healthy volunteers were consecutively included, and blood samples were collected from all participants and ozonized in vitro. PO₂, SO₂, malondialdehyde (MDA), superoxide dismutase (SOD), malformation percentage, morphology change and spatial distribution of filamentous actin (F-actin) in erythrocytes at different ozone concentrations were evaluated. After ozonation of whole blood, the median levels of PO₂ and SO₂ increased under Ozone concentrations at 40 μg/mL, 80 μg/mL and 160 μg/mL compared with samples exposed to 0 μg/mL in both AD group and control group. The MDA level was similar in samples exposed to 0 μg/mL, 40 μg/mL and 80 μg/mL ozone, while the levels of SOD increased in samples exposed to 40 μg/mL and 80 μg/mL in both AD group and control group. Compared with the samples exposed to 0 μg/mL ozone, FHb level only increased in samples exposed to 80 μg/mL and 160 μg/mL Ozone in both AD group and control group. In addition, overdosed ozone (160 μg/mL) but not therapeutic ozone concentrations (0 μg/mL, 40 μg/mL and 80 μg/mL) increased malformation percentage and morphology change of erythrocytes in both AD group and control group. In conclusion, Ozone improves oxygen content and reduces oxidative damage in blood from AD patients, and therapeutic dose ozone do not induce hemolysis and morphology change of erythrocytes.

Nanoscale membrane architecture of healthy and pathological red blood cells

Red blood cells feature remarkable mechanical properties while navigating through microcirculation vessels and during spleen filtration. An unusual combination of plasma membrane and cytoskeleton physical properties allows red blood cells to undergo extensive deformation. Here we used atomic force microscopy multiparametric imaging to probe how cellular organization influences nanoscale and global mechanical properties of cells in both physiological and pathological conditions. Our data obtained in native conditions confirmed that, compared to healthy cells, cells from patients with hereditary spherocytosis are stiffer. Through vertical segmentation of the cell elasticity, we found that healthy and pathological cells display nanoscale architecture with an increasing stiffness along the direction of the applied force. By decoupling the mechanical response of the plasma membrane from its underlying cytoskeleton, we find that both components show altered properties in pathological conditions. Nanoscale multiparametric imaging also revealed lipid domains that exhibit differential mechanical properties than the bulk membrane in both healthy and pathological conditions. Thanks to correlated AFM-fluorescence imaging, we identified submicrometric sphingomyelin-enriched lipid domains of variable stiffness at the red blood cell surface. Our experiments provide novel insights into the interplay between nanoscale organization of red blood cell plasma membrane and their nanomechanical properties. Overall, this work contributes to a better understanding of the complex relationship between cellular nanoscale organization, cellular nanomechanics and how this 3D organization is altered in pathological conditions.