ИСТИНА

The optical clearing agents (OCA) are used to improve the visualization of blood capillaries in the skin and to better assess the blood microcirculation. Digital capillaroscopy (DC) is a method widely used for visualization of human capillaries in vivo, in particular, the nail bed capillaries. However, OCA being applied to the tissue surface can penetrate to the bloodstream. Most of OCA are osmotically active. They can change the microrheological properties of blood and locally alter the diagnosed blood flow, introducing errors in the measurements using DC. The goal of this work was to demonstrate the possible effect of OCA on blood microrheology and microcirculation parameters as well as to find the ways to minimize such effect. For this reason, we examined the efficiency of 15 different OCAs. The effect of OCAs on RBC aggregation and deformability properties in vitro was measured by diffuse light scattering technique and laser diffractometry. We showed that these properties were dramatically changed after the blood was incubated with OCAs. We hypothesize that the mechanism for the observed differences is most likely that the OCAs penetrate into the capillaries and change the properties of the vessel walls and RBC. The capabilities of OCA to improve the visualization of capillary blood flow and the necessity to correct the parameters measured using DC are discussed. This work was supported by the Russian Science Foundation grant No. 23-45-00027.