Red blood cell microrheological changes and drug transport efficiency

The place of beta-adrenergic receptor blockers in the treatment of arterial hypertension: From bench-to-bedside

Arterial hypertension is a multifaceted condition influenced by numerous pathophysiological factors. The key contributors to its pathogenesis encompass an unhealthy lifestyle, dysregulation of the sympathetic nervous system, alterations in the activity of adrenergic receptors, disruptions in sodium metabolism, structural and functional abnormalities in the vascular bed, as well as endothelial dysfunction, low-grade inflammation, oxidative stress etc. Despite extensive research into the mechanisms of arterial hypertension development over the centuries, its pathogenesis remains incompletely understood, and the selection of an effective treatment strategy continues to pose a significant challenge. Arterial hypertension is characterized by a diminished sensitivity of the β-adrenergic system, leading to the utilization of β-adrenergic blockers and other antihypertensive drugs in its treatment. This review delves into the mechanisms of action of beta-adrenergic receptor blockers in the treatment of hypertension and their respective effects.

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.

A preliminary study of phosphodiesterases and adenylyl cyclase signaling pathway on red blood cell deformability of sickle cell patients

Sickle cell disease (SCD) is an inherited hemoglobinopathy characterized by chronic anemia, intravascular hemolysis, and the occurrence of vaso-occlusive crises due to the mechanical obstruction of the microcirculation by poorly deformable red blood cells (RBCs). RBC deformability is a key factor in the pathogenesis of SCD, and is affected by various factors. In this study, we investigated the effects of adenylyl cyclase (AC) signaling pathway modulation and different phosphodiesterase (PDE) modulatory molecules on the deformability and mechanical stress responses of RBC from SCD patients (HbSS genotype) by applying 5 Pa shear stress with an ektacytometer (LORRCA). We evaluated RBC deformability before and after the application of shear stress. AC stimulation with Forskolin had distinct effects on RBC deformability depending on the application of 5 Pa shear stress. RBC deformability was increased by Forskolin before shear stress application but decreased after 5 Pa shear stress. AC inhibition with SQ22536 and protein kinase A (PKA) inhibition with H89 increased RBC deformability before and after the shear stress application. Non-selective PDE inhibition with Pentoxifylline increased RBC deformability. However, modulation of the different PDE types had distinct effects on RBC deformability, with PDE1 inhibition by Vinpocetine increasing deformability while PDE4 inhibition by Rolipram decreased RBC deformability after the shear stress application. The effects of the drugs varied greatly between patients suggesting some could benefit from one drug while others not. Developing drugs targeting the AC signaling pathway could have clinical applications for SCD, but more researches with larger patient cohorts are needed to identify the differences in the responses of sickle RBCs.

Label-Free Digital Holotomography Reveals Ibuprofen-Induced Morphological Changes to Red Blood Cells

Understanding the dose-dependent effect of over-the-counter drugs on red blood cells (RBCs) is crucial for hematology and digital pathology. Yet, it is challenging to continuously record the real-time, drug-induced shape changes of RBCs in a label-free manner. Here, we demonstrate digital holotomography (DHTM)-enabled real-time, label-free concentration-dependent and time-dependent monitoring of ibuprofen on RBCs from a healthy donor. The RBCs are segmented based on three-dimensional (3D) and four-dimensional (4D) refractive index tomograms, and their morphological and chemical parameters are retrieved with their shapes classified using machine learning. We directly observed the formation and motion of spicules on the RBC membrane when aqueous solutions of ibuprofen were drop-cast on wet blood, creating rough-membraned echinocyte forms. At low concentrations of 0.25-0.50 mM, the ibuprofen-induced morphological change was transient, but at high concentrations (1-3 mM) the spiculated RBC remained over a period of up to 1.5 h. Molecular simulations confirmed that aggregates of ibuprofen molecules at high concentrations significantly disrupted the RBC membrane structural integrity and lipid order but produced negligible effect at low ibuprofen concentrations. Control experiments on the effect of urea, hydrogen peroxide, and aqueous solutions on RBCs showed zero spicule formation. Our work clarifies the dose-dependent chemical effects on RBCs using label-free microscopes that can be deployed for the rapid detection of overdosage of over-the-counter and prescribed drugs.

Development of experimental microfluidic device and methodology for assessing microrheological properties of blood

BACKGROUND AND OBJECTIVE

Microfluidics is a useful tool for investigating blood microrheology. The study aimed to present the development of a microfluidic device for assessing the microrheological properties of blood cells' suspensions and its application in patients with T2DM.

METHODS

A new microfluidic device was elaborated, connected to a system, including a microscope with a digital camera, a pump with a manometer and a computer with specially developed software. Blood cells' suspensions were investigated in a microchamber between two parallel optical slides within a 100μm distance. The motion of the blood cells in the microchamber was observed by the microscope and it was recorded and visualized by a digital camera. A method for evaluating the deformability of blood cells and a device for its implementation were used [1].

RESULTS

The pressure and flow rate ranges in the microfluidic device were specified by model suspensions of beta-ferroxy-hydroxide and red blood cells (RBC) suspensions. The pressure changes, realized by a pump (micropipette), connected to a manometer were established and the corresponding shear rates in the microfluidic device were determined. Data about the blood microrheological properties like RBC aggregation and deformability, leukocyte adhesion from a group of healthy volunteers and from patients with type 2 diabetes mellitus (T2DM) were obtained.

CONCLUSIONS

The developed device and experimental system is a promising tool for the study of blood microrheology.

Calcium/protein kinase C signaling mechanisms in shear-induced mechanical responses of red blood cells

Red blood cell (RBC) deformability has vital importance for microcirculation in the body, as RBCs travel in narrow capillaries under shear stress. Deformability can be defined as a remarkable cell ability to change shape in response to an external force which allows the cell to pass through the narrowest blood capillaries. Previous studies showed that RBC deformability could be regulated by Ca²⁺/protein kinase C (PKC) signaling mechanisms due to the phosphorylative changes in RBC membrane proteins by kinases and phosphatases. We investigated the roles of Ca²⁺/PKC signaling pathway on RBC mechanical responses and impaired RBC deformability under continuous shear stress (SS). A protein kinase C inhibitor Chelerythrine, a tyrosine phosphatase inhibitor Calpeptin, and a calcium channel blocker Verapamil were applied into human blood samples in 1 micromolar concentration. Samples with drugs were treated with or without 3 mM Ca²⁺. A shear stress at 5 Pa level was applied to each sample continuously for 300 s. RBC deformability was measured by a laser-assisted optical rotational cell analyzer (LORRCA) and was calculated as the change in elongation index (EI) of RBC upon a range of shear stress (SS, 0.3-50 Pa). RBC mechanical stress responses were evaluated before and after continuous SS through the parameterization of EI-SS curves. The drug administrations did not produce any significant alterations in RBC mechanical responses when they were applied alone. However, the application of the drugs together with Ca²⁺ substantially increased RBC deformability compared to calcium alone. Verapamil significantly improved Ca²⁺-induced impairments of deformability both before and after 5 Pa SS exposure (p < 0.0001). Calpeptin and Chelerythrine significantly ameliorated impaired deformability only after continuous SS (p < 0.05). Shear-induced improvements of deformability were conserved by the drug administrations although shear-induced deformability was impaired when the drugs were applied with calcium. The blocking of Ca²⁺ channel by Verapamil improved impaired RBC mechanical responses independent of the SS effect. The inhibition of tyrosine phosphatase and protein kinase C by Calpeptin and Chelerythrine, respectively, exhibited ameliorating effects on calcium-impaired deformability with the contribution of shear stress. The modulation of Ca²⁺/PKC signaling pathway could regulate the mechanical stress responses of RBCs when cells are under continuous SS exposure. Shear-induced improvements in the mechanical properties of RBCs by this signaling mechanism could facilitate RBC flow in the microcirculation of pathophysiological disorders, wherein Ca²⁺ homeostasis is disturbed and RBC deformability is reduced.