Erythrocyte deformability

Erythrocyte deformability refers to the ability of

Erythrocyte deformability is an important determinant of blood viscosity, hence blood flow resistance in the vascular system.[3] It affects blood flow in large blood vessels, due to the increased frictional resistance between fluid laminae under laminar flow conditions. It also affects the microcirculatory blood flow significantly, where erythrocytes are forced to pass through blood vessels with diameters smaller than their size.^{[citation needed]}

Clinical significance

Erythrocyte deformability is altered under various

Stored packed red blood cells (sometimes denoted "pRBC" or "StRBC") also experience changes in membrane properties like deformability during storage and related processing, as part of a broader phenomenon known as "storage lesion." While the clinical implications are still being explored, deformability can be indicative of quality or preservation thereof for stored RBC product available for blood transfusion.^[5][6][7] Perfusion (or perfusability) is a deformability-based metric that may offer a particularly physiologically-relevant representation of storage-induced deterioration of RBC occurring in blood banks, and the associated impacts of storage conditions/systems.^[8]

Measurement

Erythocyte deformability is a measurable property, and various means for its measurement have been explored - with each having results and significance being highly particularized to the given approach employed. Accordingly, the term is somewhat loose in the sense that a given cell or sample of cells may be deemed significantly more "deformable" by one means/metric relative to another means/metric. Thus for meaningful "apples-to-apples" comparisons involving cell deformability, it is important to utilize the same qualitative approach.^{[citation needed]}

Ektacytometry based on laser diffraction analysis is a commonly preferred (and a fairly direct) method for measuring deformability.^[9] Another direct metric is optical tweezers, which targets individual cells. Deformability can in effect be measured indirectly, such as by how much pressure and/or time it takes cells pass through pores of a filter (i.e., filterability or filtration)^[10] or perfuse through capillaries (perfusion),^[11] in vitro or in vivo, having smaller diameters than the cells'. Some deformability tests may be more physiologically-relevant than others for given applications. For example, perfusion is more sensitive to relatively small changes in deformability (compared to filterability),^[12] thus making it preferable for assessing RBC deformability in contexts where microcirculatory implications are of particular interest. Moreover, some tests may track how deformability itself changes as conditions change and/or as deformation is repeated.^{[citation needed]}

Related erythrocyte properties

Erythrocytes/RBC may also be tested for other (related) membrane properties, including erythrocyte fragility (osmotic or mechanical) and cell morphology. Morphology can be measured by indexes which characterize shape changes of differences among cells. Fragility testing involves subjecting a sample of cells to osmotic and/or mechanical stress(es), then ascertaining how much hemolysis results thereafter, and then characterizing susceptibility to or propensity for stress-induced hemolysis with an index or profile (which can be useful to assess cells' ability to withstand sustained or repeated stresses).^{[citation needed]}

Other related red blood cell properties can include adhesion and aggregation, which along with deformability are often classed as RBC "flow properties."

References