Assessment of transient changes in oxygen diffusion of single red blood cells using a microfluidic analytical platform.

Red blood cells (RBCs) capability to deliver oxygen (O(2)) has been routinely measured by P50. Although this defines the ability of RBCs to carry O(2) under equilibrium states, it cannot determine the efficacy of O(2) delivery in dynamic blood flow. Here, we developed a microfluidic analytical platform (MAP) that isolates single RBCs for assessing transient changes in their O(2) release rate. We found that in vivo (biological) and in vitro (blood storage) aging of RBC could lead to an increase in the O(2) release rate, despite a decrease in P50. Rejuvenation of stored RBCs (Day 42), though increased the P50, failed to restore the O(2) release rate to basal level (Day 0). The temporal dimension provided at the single-cell level by MAP could shed new insights into the dynamics of O(2) delivery in both physiological and pathological conditions.