Deformability based sorting of red blood cells improves diagnostic sensitivity for malaria caused by Plasmodium falciparum

Abstract

The loss of red blood cell (RBC) deformability is part of the pathology of many diseases. In malaria caused by Plasmodium falciparum infection, metabolism of hemoglobin by the parasite results in progressive reduction in RBC deformability that is directly correlated with the growth and development of the parasite. The ability to sort RBCs based on deformability therefore provides a means to isolate pathological cells and to study biochemical events associated with disease progression. Existing methods have not been able to sort RBCs based on deformability or to effectively enrich for P. falciparum infected RBCs at clinically relevant concentrations. Here, we develop a method to sort RBCs based on deformability and demonstrate the ability to enrich the concentration of ring-stage P. falciparum infected RBCs (Pf-iRBCs) by >100× from clinically relevant parasitemia (<0.01%). Deformability based sorting of RBCs is accomplished using ratchet transport through asymmetrical constrictions using oscillatory flow. This mechanism provides dramatically improved selectivity over previous biophysical methods by preventing the accumulation of cells in the filter microstructure to ensure that consistent filtration forces are applied to each cell. We show that our approach dramatically improves the sensitivity of malaria diagnosis performed using both microscopy and rapid diagnostic test by converting samples with difficult-to-detect parasitemia (<0.01%) into samples with easily detectable parasitemia (>0.1%).

Deformability based sorting of stored red blood cells reveals donor-dependent aging curves

“…The microfluidic ratchet devices were prepared as described previously 70,71 . Briefly, the master The composite structure was then bonded to a 75 x 50 mm glass slide (Corning) substrate using air plasma.…”

Deformability based Cell Sorting using Microfluidic Ratchets Enabling Phenotypic Separation of Leukocytes Directly from Whole Blood

“…Building on results from cell deformability studies performed using AFM 32 , micropipette aspiration 33, 34 and its microfluidic derivative 35 , we hypothesize that erythrocytes, leukocytes and leukocyte subpopulations can be sensitively separated based on their distinct cell deformability. Previously, the microfluidic ratchet mechanism has been shown to be able to effectively separate viable circulating tumor cells from whole blood 36 with significant improvements in yield over conventional methods as well as to separate erythrocytes infected with Plasmodium falciparum 37 from uninfected erythrocytes to improve the sensitivity of malaria diagnosis. Using oscillating flow of cells through an array of funnel shaped microstructures, we show that whole blood can be processed without clogging or fouling the filter matrix.…”

Lab-on-a-Chip Technologies for the Single Cell Level: Separation, Analysis, and Diagnostics

“…The most prominent example thereof is the increased stiffness of red blood cells infected with Plasmodium falciparum (iRBCs) compared to healthy red blood cells (RBCs) [110]. While this fact in itself has intriguing implications with sickle-cell anemia [110] and immunity towards Malaria, it has also been used to separate iRBCs from RBCs, both in theory [98,110,111] and practice [14,112]. One especially clever approach was presented by Guo et al in 2016, where an oscillating flow separated rigid from elastic RBCs through an asymmetric filter array (see Figure 4).…”

“…(e) Image of the overview design of the ratchet sorting device as well the nine outlets (O1-9). Adapted with permission from [112].…”