The potential use of nanomaterials in medicine offers opportunities for novel therapeutic approaches to treating complex disorders. For that reason, a new branch of science, named nanotoxicology, which aims to study the dangerous effects of nanomaterials on human health and on the environment, has recently emerged. However, the toxicity and risk associated with nanomaterials are unclear or not completely understood. The development of an adequate experimental strategy for assessing the toxicity of nanomaterials may include a rapid/express method that will reliably, quickly, and cheaply make an initial assessment. One possibility is the characterization of the hemocompatibility of nanomaterials, which includes their hemolytic activity as a marker. In this review, we consider various factors affecting the hemolytic activity of nanomaterials and draw the reader’s attention to the fact that the formation of a protein corona around a nanoparticle can significantly change its interaction with the red cell. This leads us to suggest that the nanomaterial hemolytic activity in the buffer does not reflect the situation in the blood plasma. As a recommendation, we propose studying the hemocompatibility of nanomaterials under more physiologically relevant conditions, in the presence of plasma proteins in the medium and under mechanical stress.

Background: Red blood cells (RBCs) undergo a natural aging process occurring in the blood circulation throughout the RBC lifespan or during routine cold storage in the blood bank. The aging of RBCs is associated with the elevation of mechanical fragility (MF) or osmotic fragility (OF) of RBCs, which can lead to cell lysis. The present study was undertaken to identify RBC properties that characterize their susceptibility to destruction under osmotic/mechanical stress. Methods: RBCs were isolated from freshly donated blood or units of packed RBCs (PRBCs) and suspended in albumin-supplemented phosphate-buffered saline (PBS). In addition, PRBCs were separated by filtration through a microsphere column into two fractions: enriched with rigid (R-fraction) and deformable (D-fraction) cells. The RBCs were subjected to determination of deformability, MF and OF, moreover, the level of cell surface phosphatidylserine (PS) and the stomatin level in isolated RBC membranes were measured. Results: In the RBC population, the cells that were susceptible to mechanical and osmotic stress were characterized by low deformability and increased level of surface PS. The OF/MF was higher in the R-fraction than in the D-fraction. Stomatin was depleted in destroyed cells and in the R-fraction. Conclusion: RBC deformability, the levels of surface PS, and membrane stomatin can be used as markers of RBC fragility.

Red blood cell (RBC) deformability, expressing their ability to change their shape, allows them to minimize their resistance to flow and optimize oxygen delivery to the tissues. RBC with reduced deformability may lead to increased vascular resistance, capillary occlusion, and impaired perfusion and oxygen delivery. A reduction in deformability, as occurs during RBC physiological aging and under blood storage, is implicated in the pathophysiology of diverse conditions with circulatory disorders and anemias. The change in RBC deformability is associated with metabolic and structural alterations, mostly uncharacterized. To bridge this gap, we analyzed the membrane protein levels, using mass spectroscopy, of RBC with varying deformability determined by image analysis. In total, 752 membrane proteins were identified. However, deformability was positively correlated with the level of only fourteen proteins, with a highly significant inter-correlation between them. These proteins are involved in membrane rafting and/or the membrane–cytoskeleton linkage. These findings suggest that the reduction of deformability is a programmed (not arbitrary) process of remodeling and shedding of membrane fragments, possibly mirroring the formation of extracellular vesicles. The highly significant inter-correlation between the deformability-expressing proteins infers that the cell deformability can be assessed by determining the level of a few, possibly one, of them.

The deformability of red blood cells (RBCs), expressing their ability to change their shape as a function of flow-induced shear stress, allows them to optimize oxygen delivery to the tissues and minimize their resistance to flow, especially in microcirculation. During physiological aging and blood storage, or under external stimulations, RBCs undergo metabolic and structural alterations, one of which is hemoglobin (Hb) redistribution between the cytosol and the membrane. Consequently, part of the Hb may attach to the cell membrane, and although this process is reversible, the increase in membrane-bound Hb (MBHb) can affect the cell’s mechanical properties and deformability in particular. In the present study, we examined the correlation between the MBHb levels, determined by mass spectroscopy, and the cell deformability, determined by image analysis. Six hemoglobin subunits were found attached to the RBC membranes. The cell deformability was negatively correlated with the level of four subunits, with a highly significant inter-correlation between them. These data suggest that the decrease in RBC deformability results from Hb redistribution between the cytosol and the cell membrane and the respective Hb interaction with the cell membrane.

Blood units are routinely collected from adult donors and stored as packed red blood cells (PRBC). The quality of PRBC, including their deformability, decreases during storage. Since PRBC transfusion has been reported to promote circulatory issues in premature neonates (PNs), they typically receive freshly stored units. To test the hypothesis that freshly stored PRBCs can provide red blood cells (RBCs) with appropriate deformability for PN recipients, we compared the deformability of PRBCs transfused to PNs with that of cord blood RBCs (CRBCs), which are known to have deformability equivalent to that of newborn RBCs (PN-RBC). We found that, on average, CRBC deformability was higher than that of PRBCs. However, both showed significant variability with overlapping ranges. A highly significant correlation was observed between cell deformability and the combined levels of specific membrane proteins (ezrin, stomatin, flotillins) and membrane-bound hemoglobin (Pearson coefficient > 0.70, p < 0.02). This study indicates that the storage duration is inadequate for selecting PRBCs for PN recipients. PRBCs with deformability similar to that of PN-RBCs could enable safer and more effective transfusions for PN patients. Measuring membrane proteins alongside membrane-bound hemoglobin can serve as a useful method for selecting appropriate PRBC units for transfusion to PNs.