High-throughput and label-free screening of red blood cell stiffness: A study of sickle cell disease

Understanding the morphological and mechanical changes in cells are important for diagnostic and treatment methods in various diseases. In sickle cell disease (SCD), the mutated hemoglobin (HbS) aggregates inside the red blood cells (RBCs), making them rigid and, in extreme cases, sickle-shaped, resulting in anemia, episodes of pain, and multiple organ damage. Existing techniques are too costly and insensitive since the effect of the HbS gene (heterozygous and homozygous) is variable both in prevalence and clinical manifestations. In this work, we present a label-free, cost-effective, high-throughput electro-fluidic technique to study changes in the mechanical and morphological characteristics of RBCs. We validate our device by quantitatively comparing the mechanical properties of RBCs as a function of stiffness-altering drug (Latrunculin-A) with measurements using AFM. We demonstrate the on-site application of our system by screening SCD patients based on their RBC stiffness changes. The signatures of patient-specific heterogeneity in the RBC mechanical properties may help in monitoring clinical variability and identification of high-risk patients along with targeted therapies. The versatility of our measurements opens the whole cell stiffness as a preliminary screening biomarker in other haematological conditions, tumor cell identification, in veterinary sciences as well as in evaluating hydrogel technologies.