In vivo clearance of stored red blood cells.

In this issue of , Roussel et al focus on the morphologic alterations of stored red blood cells (RBCs) and their impact on the ability of cells that have been damaged by storage to circulate after transfusion, which is the minimum requirement for the physiological function of transfused RBCs regarding oxygen transport. Specifically, they describe the progressive accumulation in stored units of a population of RBCs with reduced size (mean projected surface area <43 μm), which they define as storage-induced microerythrocytes (SMEs). They thus combine elegant murine models and ex vivo perfusion of human spleens to demonstrate that SMEs are more rapidly removed than RBCs with normal morphology from the bloodstream of the recipient upon transfusion.