(174ba) Correlation of a Shape Factor and Degree of Saturation of Red Blood Cells to Vaso-Occlusive Episodes in Sickle Cell Disease and Potential for Magnetic Separation

Patients with sickle cell disease (SCD) can experience intermittent episodes of Vaso-occlusive episodes (VOE) leading to acute pain. Additionally, patients can experience changes (such as nociceptive, neuropathic, and opiate induced hyperalgesia) which results in increases in pain over there lifetime. Developing a test that can delineate VOE from steady state and differentiate it from chronic pain continues to pose an elusive problem in SCD. It not only impacts endpoints in clinical studies, but it can also pose a significant challenge for the patient in terms of timely clinical diagnosis and treatment of pain.

Cell Tracking Velocimetry, (CTV), tracks cells on a single cell basis in a very high magnetic energy gradient. This instrument allows us to use the cell’s magnetic, v_x, and settling velocities, v_y, to be transformed into estimates of the oxygen saturation and deformity of the red blood cells, (RBCs). Based on statistical correlations of these measurements to patient status, VOE can be independently identified.

A total of 39 SCD samples were evaluated (22 non-transfused, and 16 transfused) of which 19 were SS, 14 were SC, and 5 were SB+ subtypes. The patients’ samples and clinical state was deidentified for initial laboratory evaluation. The CTV instruments return two types of data: magnetic velocity and settling velocity. It was demonstrated that the range of the magnetic velocity of the top and bottom 1 percent of the measured velocities (i.e. the fastest and slowest moving RBCs) correlates to a patient in VOE, when compared to normal, healthy RBCs and SCD patients in steady state (p > 0.0168). Further, the ratio of the magnetic to settling velocity of the top and bottom 1 percent of these ratios correlates to a patient in VOE, when compared to normal RBCs and SCD patients in steady state (p > 0.0003). These correlations are significant for both RBCs under deoxygenated and ambient air conditions.

Furthermore, this difference in magnetic properties of SCD RBCs, relative to normal RBCs, presents the potential to magnetically separate SCD RBCs from a mixture of SCD RBCs and regular RBCs. Such mixtures are typically discarded when SCD patients are treated with a “RBC exchange”. RBC exchanges are the primary treatment for SCD patients with high numbers of VOCs.

The performance of packed, magnetically induced, magnetic columns, such as a Miltenyi MACS column, is being modeled using relationship(s) previously developed by other researchers focused on magnetic removal of magnetic particles. Current results will be presented.