Microelasticity of red blood cells in sickle cell disease

Abstract

Translation of cellular mechanics findings is crucial in many diseases, including Alzheimer’s disease, Parkinson’s disease, type II diabetes, malaria, sickle cell disease, and cancer. Atomic force microscopy (AFM) is appropriate for measuring mechanical properties of living and fixed cells due to its high force sensitivity and its ability to measure local and overall properties of individual cells under physiological conditions. A systemic force–displacement curve analysis is reported on the quantification of material stiffness via AFM using two theoretical models derived from the Hertz model. This analysis was applied to red blood cells from patients with sickle cell disease to determine the Young’s modulus of these cells in the oxygenated and deoxygenated state. Sickle cell disease pathophysiology is a consequence of the polymerization of sickle hemoglobin in red blood cells upon partial deoxygenation and the impaired flow of these cells in the microcirculation. A model is presented for a four-sided pyramidal indenter that is subsequently shown to have a better fit to the obtained data than that using a model of a parabolic indenter. It is concluded that deoxygenation and therapeutic treatment have a significant impact on the stiffness. This analysis presents a new approach to addressing medical disorders.