Red blood cells deformability as a malaria biomarker

Half of the world's population, particularly in economic underdevelopment areas, is at risk of contracting malaria. The disease evolution causes biochemical, optical and morphological changes in host red blood cells (RBCs), so the early detection of these changes allows to acknowledge the presence and status of malaria. The main objective of this work is to study the RBCs deformability as a malaria biomarker, by measuring the deformation index (DI) of the RBCs in polydimethylsiloxane microfluidic channels. It was performed a comparative study among healthy ovine RBCs and glutaraldehyde synthetically modified RBCs (that were modified to increase their stiffness and mimic the behavior of the malaria parasite in cells). It was verified that healthy RBCs naturally deform when they pass through contractions with dimensions close to their average dimensions and quickly recover to their original shape after exiting the contraction. In contrast, when glutaraldehyde modified RBCs were tested, it was observed the presence of occlusions in the 6 and 8 μm width constriction microchannels, for concentrations higher than 0.024 and 0.032%, respectively. Also, the almost instantaneous shape recovery capacity, observed in healthy RBCs, was affected by the rigidiflcation treatment, since the DI analyzed at the outlet of the microchannel constriction was higher for modified samples, meaning that the cells did not recover to its original shape. For the 10 μm width constrictions, no occlusion was observed and the RBCs DI was similar for both microchannel inlet and outlet. Overall, it can be concluded that the increase in RBC stiffness causes the decrease of the RBCs deformability and the cell shape recovering capacity.