Sickle cell disease severity prediction from the magnetic signature and hemoglobin content of blood cells - SUMMARY Sickle cell disease (SCD) is the most prevalent genetic blood disorder, caused by a single point mutation in the β-globin subunit of hemoglobin (Hb), the protein contained in red blood cells (RBCs) responsible for oxygen delivery to the tissues. The condition affects millions of people worldwide, primarily of African ancestry or Blacks, who often see themselves treated unfairly when seeking medical care due to the color of their skin. The major complication of the disease is the development of acute pain episodes known as vaso-occlusive crisis (VOC), that result in severe end-organ damage and a shortened lifespan. VOC is caused by vascular occlusion due to the accumulation in the blood of sickle-shaped, rigid, RBCs that become trapped in capillary blood vessels. Since VOC is responsible for an estimated 95% of SCD hospitalizations, and it is also employed as a key predictor of death, it is critical to find a way to drive early detection of VOC to support preventative interventions, better manage the condition and improve the life quality and expectancy of SCD patients. It has been recently demonstrated the protecting role of patrolling monocytes (PMo) in SCD, as they scavenge endothelial-adherent sickle RBCs. We hypothesize that both irreversibly deoxygenated sickle RBCs and PMos count, their magnetic susceptibility, and their intracellular analysis (in terms of iron (Fe), Hb, and RBC content) could be used to predict the potential development of VOC. Due to the magnetic properties of (deoxygenated) Hb, and by extension, irreversibly deoxygenated sickle RBCs, magnetism could be exploited for the simultaneous count and analysis of both cell types (RBCs and monocytes) in SCD and to relate these parameters to the development of VOC. Our recent research has demonstrated a difference between the magnetic/physical properties of sickle RBCs and healthy RBCs, which becomes more evident when the SCD patients are in crisis. We have also demonstrated for the first time the paramagnetic properties of a subset of monocytes, and the higher magnetic susceptibility of PMos in comparison to classical monocytes. Thus, this project aims to study the differences between the number, magnetic properties, size/density, and RBC/Hb/Fe content of RBCs and monocytes obtained from healthy blood donors and patients with SCD at 5 different clinical states (from least severe to VOC), and will try to establish a relationship between these cells’ properties and the development of VOC. We will employ our custom, permanent magnet-based devices for the analysis of the cells and their separation, using fast, inexpensive, and label-free approaches. We expect that single-cell magnetometry can be employed to gain a better understanding of the factors leading to the development and potential prediction of VOC, to determine the severity of the disease and to be used as a quantitative measure for the diagnosis of VOC. Our studies will also provide guidelines for the design of a novel magnetic device for the separation and quantification of magnetic cells in the blood of SCD individuals with potential diagnostic value.
