ИСТИНА

Blood composition as well as the parameters characterizing the structure and dynamics of blood and tissues surrounding the blood microvessels are the factors that determine blood fluidity and efficiency of performing the functions of transporting and delivering the gases (oxygen and carbon dioxide) and nutrients all throughout the human body. Age-related changes in the organism and most of socially important diseases are followed and highly determined by the alteration of these parameters from normal values. Thus the ability to measure and monitor these parameters in norm and their alterations in pathology is essential for adequate estimation of the patients’ state, the ways to improve the treatment procedure and to correct the patients’ hemorheology. In our work, we combined several laser and optical techniques to perform a complex study of various parameters related to blood structure and dynamics by means of imaging and measurement. In particular we used: diffuse light scattering (DLS); laser diffractometry (LD); optical trapping and manipulation (OT), videocapillaroscopy (VC) and two-photon tomography (TPT) and fluorescence life-time imaging (FLIM)). Three former techniques were used for in vitro measurements with fresh samples of blood stabilized with EDTA drawn from either healthy donors or patients suffering from various diseases such as hypertension, heart failure and/or diabetes mellitus. Three latter techniques were used for in vivo measurements and imaging. We also measured the parameters related to erythrocyte aggregation in model solutions of certain blood plasma proteins known as aggregation agonists or inhibitors. In particular, we measured the forces of aggregation and disaggregation of individual erythrocytes with OT [1,2], as well as the aggregation index, characteristic half-time of aggregation and the critical shear stress with a whole blood aggregometer implementing the DLS technique. We used the conventional LD technique (ektacytometry) to measure the average value of deformability of the erythrocytes in the sample and upgraded the technique to enable measuring the parameters of deformability distribution, which is essential for clinical application of the technique [3]. We performed in vivo imaging of the blood flows in nailfold capillaries and the perivascular zone (PZ) around them with high resolution VC technique. TPT and FLIM was used to investigate the PZ composition, and this enabled us to clearly demonstrate that PZ corresponds to the border of viable epidermis and it was suggested that the PZ size variations were due to the different amounts of interstitial fluid [4]. The obtained results allow to suggest that the PZ size measured with nailfold VC can be used as a novel quantitative non-invasive marker sensitive of the severity of such diseases as heart failure.