Use of hydroxyethyl starch for inducing red blood cell aggregation

Aggregation of human red blood cells (RBC) remains of biological and clinical interest. Replacement of plasma proteins by polymers to induce RBC aggregation may help to unravel the fundamentals of the aggregation process. Two theories exist to explain RBC aggregation mechanisms: a depletion and a bridging theory. RBC aggregation induced by hydroxyethyl starch (HES) increases with polymer size, which suggests that aggregation is induced via the bridging theory. In this study, the electrophoretic mobility (EPM) was measured to investigate RBC aggregation induced by 200 kDa HES polymers. Also, we evaluated if these polymers were useful for demonstrating aggregation differences between RBCs from healthy and type-1 diabetes mellitus (T1DM) subjects. Our results demonstrate that EPM values of RBCs in 200 kDa HES solutions were less negative than could be predicted by the viscosity of the suspension, supporting the bridging theory. Furthermore, aggregation analysis using the LORCA demonstrated that 200 kDa HES solution enhanced RBC aggregation of healthy and diabetic subjects similarly as standard 500 kDa dextran solutions.our data supports the bridging mechanism underlying 200 kDa HES induced RBC aggregation. In addition, both polymers are useful for demonstrating cellular induced aggregation differences between RBCs from healthy and T1DM subjects.