Exploring the Interplay Between Polycations and Red Blood Cells

The interaction between polycations and red blood cells (RBCs) has garnered significant interest in biophysical research, particularly regarding hemolysis and agglutination. Recent studies have explored how the behavior of native and desialylated RBCs changes when suspended in albumin, especially in the presence of polycations. Interestingly, when 10 mM of polycations was added, no significant differences in hemoglobin and potassium releases were observed between the two types of RBCs, suggesting that each protein exhibits distinct behaviors in different environments.

One notable finding is that the order in which charged species are introduced can significantly influence the outcomes regarding agglutination and hemolysis. While some polycations displayed similar behavior, others did not show sensitivity to the order of addition. In the case of desialylated RBCs suspended in albumin, the order of addition appeared not to affect hemolysis, indicating that sialic acids play a critical role in the complexation at the cell surface.

The complexity of plasma composition, which is rich in proteins with varying polyelectrolyte properties, poses challenges when assessing how synthetic polycations interact with whole blood. Albumin, as a predominant plasma protein, was studied separately, revealing that it does not exhibit protective effects on either native or desialylated RBCs, except under specific conditions of hemolysis monitoring. Interestingly, when RBCs were introduced into a mixture of polymer with albumin, the resulting hemolysis was greater than when the polymer was added to the RBC suspension in albumin.

The research underscores the notion that polyanion-polycation complexes can significantly impact RBC viability, often more than the polycations alone. The study also highlighted the rapid establishment of protein-polymer interactions, where even a brief one-minute contact was sufficient to initiate protective effects from the protein. Additionally, the collection of a white pellet during centrifugation of plasma or poly-L-lysine (PLL) in the absence of RBCs supports the occurrence of protein-polycation complexation.

The toxicological implications of polycations, particularly their effects on RBCs, remain to be fully understood. While high molar mass PLL is known to be toxic in vivo, little information exists regarding the behavior of other polycations. This highlights the need for further investigation into the structural characteristics of synthetic macromolecules and their systemic effects when administered intravenously. Current findings suggest that factors such as hydrophobicity and the presence of permanent quaternary ammonium charges may significantly contribute to the perturbation of RBCs, leading to agglutination and hemolysis.