Red blood cell lingering modulates hematocrit distribution in the microcirculation

Understanding the distribution of red blood cells (RBCs) in the microcirculation is crucial for assessing oxygen delivery and solute transport to tissues. In this study, we investigate the influence of RBC partitioning at successive bifurcations on hematocrit heterogeneity, which refers to the volume fraction of RBCs in blood within microvessels. Traditionally, RBCs were believed to partition disproportionately based on fractional blood flow rates, resulting in predictable hematocrit distributions. However, recent investigations have revealed deviations from this expected behavior on both temporal and time-average scales.

To explore these deviations, we employed a combination of in vivo experiments and in silico simulations, focusing on the microscopic behavior of RBC lingering. We introduce a novel method to quantify the extent of cell lingering at highly confined capillary-level bifurcations, demonstrating its correlation with deviations from established empirical predictions by Pries et al. Moreover, we examine how bifurcation geometry and cell membrane rigidity influence RBC lingering. Notably, we find that rigid cells exhibit reduced lingering compared to softer ones.

Our findings emphasize the importance of considering RBC lingering as a significant mechanism in the study of microcirculatory abnormalities associated with diseases like malaria and sickle-cell disease. Additionally, this research sheds light on how pathological conditions, such as thrombosis, tumors, and aneurysms, can alter the microvascular networks. By comprehensively understanding the role of RBC lingering, we can enhance our understanding of how abnormal RBC rigidity affects microcirculatory blood flow and contribute to the development of targeted interventions for various vascular disorders.