ИСТИНА

The composition of the blood, as well as parameters characterizing the structure and dynamics of the blood and tissues surrounding the blood microvessels, are factors that determine the fluidity of the blood and the efficiency of transport and delivery of gases (oxygen and carbon dioxide) and nutrients throughout the entire volume of the human body. In modern hemorheological studies, laser and optical methods are widely used, which allow a comprehensive study of deviations from the norm of various parameters related to the structure and dynamics of blood through visualization and measurement. In particular, the following are used: diffuse light scattering (DLS); laser diffractometry (LD); optical tweezers (OT), video capillaroscopy, speckle contrast spectroscopy, two-photon tomography and fluorescence imaging. The first three methods are used for in vitro measurements using fresh EDTA-stabilized blood samples taken from healthy donors or patients suffering from various diseases such as diabetes and hypertension. The last four methods are used for in vivo measurements and imaging. In addition, parameters related to red blood cell aggregation are measured in model solutions of certain plasma proteins known as aggregation agonists or inhibitors to study the mechanisms of aggregation. In particular, the aggregation and disaggregation forces of individual red blood cells are measured using OD, aggregation index is measured, characteristic aggregation time and critical shear stress are measured in whole blood samples using an aggregometer by DLS method. In our work, the traditional LD (ectacytometry) method, used to measure the average value of the deformability of erythrocytes in a sample, is improved in such a way that it becomes possible to measure the parameters of cell distribution by deformability, which is important for the clinical application of the method. Blood flow in the capillaries is visualized using digital capillaroscopy methods, which makes it possible to determine several parameters of the flow in the capillaries of the human nail bed. Also, in vivo visualization of blood flow over large areas of the microcirculatory system in laboratory animals is performed using laser speckle-contrast spectroscopy. The work was supported by the Russian Science Foundation (grant No. 23-45-00027).