A few upstream bifurcations drive the spatial distribution of red blood cells in model microfluidic networks

Abstract

The physics of blood flow in small vessel networks is dominated by the interactions between Red Blood Cells (RBCs), plasma and blood vessel walls. The resulting couplings between the microvessel...

Pericyte remodeling is deficient in the aged brain and contributes to impaired capillary flow and structure

“…This non-uniform partitioning of blood cell flow at capillary bifurcations reflects the Zweifach-Fung effect 33 , where increased flow rate in a dilated capillary pulls a larger fraction of RBCs into the dilated daughter branch. These local upstream changes can have propagating effects within the capillary network 34 , as we also observed decreased flow at downstream, convergent bifurcations (Fig. 7k–m ).…”

Rheology and structure of a suspension of deformable particles in plane Poiseuille flow

“…From the pellet, successive dilutions were performed using 3 suspending solutions with different viscosities. Following an initial suggestion by Roman et al 22 , which has been fruitfully exploited in several subsequent studies [23][24][25][26][27] , the density of the suspending solutions was adjusted with Optiprep (iodixanol solution, Axis Shield) to match the average density of red blood cells and thus avoid sedimentation during the experiments. Three solutions where prepared, respectively with (a) water 68.5 %, Optiprep 31.5 %, PBS, BSA 0.1 %, of viscosity 1.6 mPa.s at 20 • C ; (b) water 72.5 %, Optiprep 27.5 %, Dextran 100 kDa 6.5 %, PBS, BSA 0.1 %, of viscosity 5.8 mPa.s at 20 • C ; (c) water 75 %, Optiprep 25 %, Dextran 100 kDa 10 %, PBS, BSA 0.1 %, of viscosity 8.1 mPa.s at 20 • C. BSA (Bovine Serum Albumin) aims at maintaining an initial coating of the walls of the microfluidic system to prevent cell adhesion.…”

“…This is a consequence of the non homogeneous distribution of cells across the channel thickness and the formation of a cell-free layer near walls, leading to an average velocity of red blood cells higher than the average fluid velocity. Tube volume fraction was determined by an effective absorbance measurement of flowing red blood cells (Beer-Lambert law), a method that has proven to be reliable up to rather high volume fractions levels 23,27,44,45 . The effective absorption coefficient was calibrated on diluted samples of cells, that could be counted individually.…”

Influence of storage and buffer composition on the mechanical behavior of flowing red blood cells

“…They are themselves strongly influenced by the mechanical properties of the RBCs. The centered RBC distribution also influences their repartition at the level of bifurcations, leading to a heterogeneous distribution of the haematocrit in the microcirculation (17)(18)(19)(20)(21)(22)(23)(24)(25).…”

“…Running experiments in microgravity conditions is one of them ( 14), yet it poses issues in terms of access, cost and compatibility between the allotted microgravity time and the needed experimental time. The much more accessible technique of density matching was introduced in the community in (50), then used in several studies (16,21,22,25,48,(51)(52)(53)(54)(55). By using iodixanol solutions, agreement between the mean density of RBCs and the carrying fluid can be reached, while the viscosity remains in an acceptable range (around 1.5 to 1.6 mPa.s at room temperature, see Section Viscosimetry)…”