ABSTRACT
In this chapter, we review the principles and capabilities of optical techniques based on the interaction of light with whole-blood or red blood cell (RBC) suspensions to assess the parameters of blood microcirculation and microrheology. Several methods providing in vitro measurements of microrheologic parameters and in vivo monitoring of blood microcirculation are discussed. The former methods include aggregation and deformability properties of RBCs, forces of their pair interaction, and aggregation rate measured by diffuse light scattering, laser diffractometry, and laser trapping and manipulation techniques. Digital vital capillaroscopy for the estimation of the blood capillary velocity, the presence or absence of aggregates, and stasis in nail bed terminal capillaries is outlined. Special attention is paid to the alterations of these RBC properties in patients suffering from type 2 diabetes mellitus (DM) without and with concomitant diseases. Next, we show that in patients with DM, the ability of RBCs to deform is slightly reduced while the aggregation rate and forces of cell interaction are significantly increased relative to the normal values in healthy individuals. The blood microcirculation in nail bed capillaries is impaired as well. Furthermore, we demonstrate that the alterations of the parameters measured in vivo and in vitro for patients suffering from DM are interrelated. Good agreement between the results obtained with different techniques and their applicability for the diagnostics of microrheological properties of blood are demonstrated. Finally, we substantiate the possibility of using the reviewed methods in clinical practice as appropriate techniques for estimating blood microcirculation and microrheology disorders in DM.
