How is the red blood cell deformability affected by the oxygen transport?

Abstract. An increase in the neural activity of a normal brain is accompanied by an elevation in local blood flow rate to satisfy the accelerated demand for glucose and oxygen. This is particularly important in cerebral blood flow due to a limited energy reserve that requires tight neurovascular coupling. The partnership between neural activity and local blood flow rate is termed functional hyperemia. The mechanisms behind this tight neurovascular coupling remain elusive to this day despite many decades of research. Recent experimental measurements, however, have identified red blood cells (RBCs) as regulators of brain capillary perfusion. These experiments reveal that RBCs respond to a decrease in local oxygen concentration by increasing their deformability thus leading to an increase in the cell velocity in capillaries. It is hypothesized that the change in deformation occurs due to interactions between deoxygenated hemoglobin inside the cells and band 3 proteins in the RBC membrane. Following the results of these recent experiments, a microfluidic platform is designed and built to investigate the effect of oxygen transport on the derformability of red blood cells. The platform is complemented with numerical simulations to calculate the shear modulus of RBCs based on their size and velocity. With a large array of diseases such as Chronic Fatigue Syndrome (CFS) and COVID19 directly influence the mechanical and chemical properties of RBCs and many of the symptoms such as fatigue, orthostatic intolerance, and cognitive disturbances suggest poor tissue oxygenation, we are investigating if changes in RBC flexibility and its response to oxygen concentration can act as a biomarker for such diseases.