Depletion interaction forces contribute to erythrocyte-endothelial adhesion in diabetes

Forces of interaction of red blood cells and endothelial cells at different concentrations of fibrinogen: Measurements with laser tweezers in vitro

Blood microrheology depends on the constituents of blood plasma, the interaction between blood cells resulting in red blood cell (RBC) and platelets aggregation, and adhesion of RBC, platelets and leukocytes to vascular endothelium. The main plasma protein molecule -actuator of RBC aggregation is fibrinogen. In this paper the effect of interaction between the endothelium and RBC at different fibrinogen concentrations on the RBC microrheological properties was investigated in vitro. Laser tweezers were used to measure the RBC-endothelium interaction forces. It was shown for the first time that the interaction forces between RBC and endothelium are comparable with the RBC aggregation forces, they increase with fibrinogen concentration and reach the saturation level of about 4 pN at the concentration of 4 mg/ml. These results are important for better understanding the mechanisms of RBC and endothelium interaction and developing the novel therapeutic protocols of the microrheology correction in different pathologies.

Polymer-induced adhesion of endothelial cells

The effects of neutral dextran concentration and molecular mass on the adhesion of endothelial cells (EC) to siliclad-covered glass surfaces were studied using interference reflection microscopy (IRM). Results indicate that close contact of the EC to the glass slides is markedly enhanced in the presence of 500 kDa dextran, with this increase reflected by both the speed of forming close contact as well as the size of the contact area. This increased adhesion is attributed to the reduction in surface concentrations of large polymers and, therefore, to the attractive forces caused by depletion interaction. Our findings suggest that depletion could play an important role in cell-cell or cell-surface interactions via accelerating and enhancing close contacts. This interaction should thus be considered in vivo and in vitro for specific potential applications, such as cell culture and cell adhesion to biomimetic surfaces. It should therefore be of particular interest in a wide range of biomedical applications.

Hypercholesterolemic patients have higher eryptosis and erythrocyte adhesion to human endothelium independently of statin therapy

BACKGROUND

Phosphatidylserine (PS) externalization out of the membrane facilitates the eryptotic erythrocytes (EE) binding to endothelial cells (EC), potentially leading to atherosclerosis. Thus, the levels of eryptosis and interactions of EE-EC in hypercholesterolemic patients, either non-medicated or medicated, compared with healthy subjects were studied.

METHODS

A total of 56 subjects clustered into three groups: (control (n = 20), hypercholesterolemic non-treated (HCNT) (n = 15), and statin-treated (HCT) (n = 21)) were enrolled in this cross-sectional study. Biochemical parameters were determined with validated and standard methods. PS exposure was estimated from annexin-V-binding, cell volume from forward scatter (FSC), and GSH from CMFDA fluorescence by flow cytometry. The erythrocyte-EC adhesion assay was performed by using the parallel-plate flow chamber technique.

RESULTS

Higher PS externalization and adhesion of erythrocytes to EC (P < .05) was found in hypercholesterolemic subjects, regardless of statin treatment, compared with the control group. Although no correlation between FSC and PS externalization with other parameters was found, GSH was inversely correlated with erythrocyte adhesion, which was significantly correlated with total cholesterol, LDL-c, and apolipoprotein B.

CONCLUSION

The link between hypercholesterolemia and eryptosis suggests a possible detrimental impact of this binomial on endothelial function with possible further development of atherosclerosis and microcirculation problems in hypercholesterolemic patients, independently of statin therapy.

Do We Store Packed Red Blood Cells under "Quasi-Diabetic" Conditions?

Red blood cell (RBC) transfusion is one of the most common therapeutic procedures in modern medicine. Although frequently lifesaving, it often has deleterious side effects. RBC quality is one of the critical factors for transfusion efficacy and safety. The role of various factors in the cells’ ability to maintain their functionality during storage is widely discussed in professional literature. Thus, the extra- and intracellular factors inducing an accelerated RBC aging need to be identified and therapeutically modified. Despite the extensively studied in vivo effect of chronic hyperglycemia on RBC hemodynamic and metabolic properties, as well as on their lifespan, only limited attention has been directed at the high sugar concentration in RBCs storage media, a possible cause of damage to red blood cells. This mini-review aims to compare the biophysical and biochemical changes observed in the red blood cells during cold storage and in patients with non-insulin-dependent diabetes mellitus (NIDDM). Given the well-described corresponding RBC alterations in NIDDM and during cold storage, we may regard the stored (especially long-stored) RBCs as “quasi-diabetic”. Keeping in mind that these RBC modifications may be crucial for the initial steps of microvascular pathogenesis, suitable preventive care for the transfused patients should be considered. We hope that our hypothesis will stimulate targeted experimental research to establish a relationship between a high sugar concentration in a storage medium and a deterioration in cells’ functional properties during storage.

Impaired deformability and association with density distribution of erythrocytes in patients with type 2 diabetes mellitus under treatment

BACKGROUND

Disturbed microcirculation is related to diabetic complications, and erythrocyte deformability is a critical factor regulating microcirculation.

OBJECTIVES

To know the relationship between the impaired deformability and density profile in diabetic erythrocytes.

METHODS

We recruited patients with type 2 diabetes (n = 15, diabetic group) and age- and sex-matched non-diabetic subjects (n = 15, control group). Erythrocyte density (ED) profile was obtained by the phthalate ester separation technique. ED distribution was fitted by sigmoidal curve, yielding specific gravity of phthalate ester allowing passage of half erythrocytes population (ED50) and slope factor. Erythrocyte deformability was estimated by our specific filtration technique.

RESULTS

Diabetic group showed significantly (p < 0.001) higher HbA1c and fasting blood glucose concentration. Erythrocyte deformability in diabetic group was impaired as compared with that in control group (p < 0.001) and proportional to HbA1c (p = 0.009). However, ED50 and the slope factor in diabetic group did not differ from respective parameters in control group.

CONCLUSIONS

This study demonstrated that erythrocyte deformability was impaired in diabetic patients even under treatment. HbA1c up to 7.5% is concluded not to alter the erythrocyte density but to impair the deformability, which might be a warning to clinicians for prevention of diabetic complications.

Red Blood Cells: Chasing Interactions

Human red blood cells (RBC) are highly differentiated cells that have lost all organelles and most intracellular machineries during their maturation process. RBC are fundamental for the nearly all basic physiologic dynamics and they are key cells in the body's respiratory system by being responsible for the oxygen transport to all cells and tissues, and delivery of carbon dioxide to the lungs. With their flexible structure RBC are capable to deform in order to travel through all blood vessels including very small capillaries. Throughout their in average 120 days lifespan, human RBC travel in the bloodstream and come in contact with a broad range of different cell types. In fact, RBC are able to interact and communicate with endothelial cells (ECs), platelets, macrophages, and bacteria. Additionally, they are involved in the maintenance of thrombosis and hemostasis and play an important role in the immune response against pathogens. To clarify the mechanisms of interaction of RBC and these other cells both in health and disease as well as to highlight the role of important key players, we focused our interest on RBC membrane components such as ion channels, proteins, and phospholipids.