Significance of Extensional Stresses to Red Blood Cell Lysis in a Shearing Flow

Abstract

Traditionally, an empirical power-law model relating hemolysis to shear stress and exposure time has been used to estimate hemolysis related to flow--however, this basis alone has been insufficient in attempts to predict hemolysis through computational fluid dynamics. Because of this deficiency, we sought to re-examine flow features related to hemolysis in a shearing flow by computationally modeling a set of classic experiments performed in a capillary tube. Simulating 21 different flows of varying entrance contraction ratio, flowrate and viscosity, we identified hemolysis threshold streamlines and analyzed the stresses present. Constant damage thresholds for radial and axial extensional stresses of approximately 3000 Pa for exposure times on the order of microseconds were observed, while no such threshold was found for the maximum shear stress or gradient of the shear stress. The extensional flow seen at the entrance of the capillary appears to be most consistently related to hemolysis. An account of how extensional stresses can lead to lysis of a red cell undergoing tank-tread motion in a shearing flow is provided. This work shows that extensional components of the stress tensor are integral in causing hemolysis for some flows, and should be considered when attempting to predict hemolysis computationally.

Rheological behavior of human blood in uniaxial extensional flow

“…Furthermore, generating an extensional flow field is a useful way to stretch deformable materials, such as red blood cells [12] or DNA molecules [13,14], and investigate their 3 viscoelastic response under controllable flow conditions. For red blood cells, it is important to note that extensional stresses are an important factor for cell hemolysis, as demonstrated by Down et al [15] in the flow through an axisymmetric contraction, similar to what is possibly found in blood vessels.…”

Experimental observation of the asymmetric instability of intermediate-reduced-volume vesicles in extensional flow

“…Experiments and numerical work have provided evidence that extensional fluid stresses are integral to hemolysis (instantaneous rupture of RBCs), and existing models for hemolysis that only account for simple shear stresses are insufficient. 26,27 Studying the deformation and stability of vesicles in extensional flow would improve our mechanistic understanding of cell damage within medical applications, such as RBC lysis in medical devices and artificial organs 27 and vesicle drug-delivery systems. 28,29 Within the area of vesicle dynamics research, the flow field around vesicles sedimenting under gravity is primarily elongational flow.…”

A parametric investigation of blood flow in a wedge with non‐uniform viscosity and wall friction

“…Later, Puig-De-Morales-Marinkovic et al [36] have found experimentally that red blood cell (RBC) has an exponential non-Newtonian power-law time-dependent characteristic behavior which is consistent with current study. Another evident to the rheological behavior of blood flow due to extensional stresses was found by Down et al [37] and Sousa et al, [38] while the latter has exhibited nonlinear viscoelastic behavior, such as the viscous component dominated over the elastic component. Some applications of blood rheological elastic part can be found in Campo-Deaño et al [39] Particularly, the tremendous effect of the nonlinear viscosity on the RBC non-Newtonian fluid behavior was demonstrated by Flormann et al [40] Advanced analytic and experimental models of blood and other rheological fluids have been proposed recently by [41][42][43].…”

“…The idea to use the non-Newtonian fluid was due to the fact that the Newtonian model does not give an appropriate response to many discrepancies observed in experiments. [35][36][37][38][39][40][41][42][43] In this section a solution for the non-Newtonian case ( = 2) will be examined alongside edge conditions (30) and the normalized condition (20b). By substituting = 2 into Equations (9) and (15), we get:…”