ИСТИНА

The state of human organism greatly depends on blood microcirculation, which in turn depends on the microrheologic properties of red blood cells (RBC), in particular, their intrinsic properties of deformability and aggregation that may be interdependent [1]. The aim of this work is to study the effect that RBC deformability has on their aggregation properties in in-vitro conditions. The blood was drawn from a healthy individual and RBC were incubatied in glutaraldehyde solutions (in a range from 0 to 0.004%) or in autologous plasma at different osmolarities (from 200 to 600 mOsm/kg) to change their deformability. Three optical techniques described in detail in [2] were used to study the cells. The first, laser diffractometry, was used on ditute suspensions of RBC to evaluate their deformability. The second, laser aggregometry, was used on whole blood samples to retrieve some of the RBC aggregation properties, e.g., the shear stress required to disaggregate the RBC aggregates in flow conditions. The last, laser tweezers, was used to manipulate a couple of cells at a time in order to assess their aggregation time and interaction force. Statistical analysis of the experimental data showed that both techniques, aggregometry and laser tweezers, produce compatible results. With the RBC becoming more rigid some of the aggregation properties change, e.g., the aggregation rate decreases, while others, like their hydrodynamic strength, stays unchanged. For example, after incubation in 0.002% glutaraldehyde solution the RBC deformability drops by 31±4% and this leads to a decrease by 26±5% in the aggregation index. Also, the aggregation force significantly drops in high osmolarity solutions, while the disaggregation force remains the same. Osmolarity of 350 mOsm/kg makes the RBC 44±2% more rigid and the aggregation force decreases by 26±9%. This may mean that there is an underlying complex relationship — the RBC aggregate formation is dependent on the deformability of the membrane, while their disaggregation is not. Certainly, this conclusion is valid only to in-vitro conditions. Additional experiments are needed to relate them to in-vivo conditions. This work is supported by Russian Foundation of Basic Research grant (17-02-01200).