RBCs, with a diameter of 8 µm, must squeeze through narrow microvascular spaces and endothelial clefts just 1 to 2.5 µm wide. RBC deformability decreases with cellular age and cold storage, but the extent to which splenic clearance selectively removes RBCs with reduced deformability from circulation remains poorly understood. In a murine model, RBCs pooled from seven female mice were treated with aminotriazole, which induces oxidative stress and reduces cell deformability in older cells. Using two distinct fluorescent labels, donor control and aminotriazole-treated RBCs were first labeled and then transfused into seven female mice in a 1:1 ratio, with periodic sampling over five weeks. Within the first 24 hours, 27.5% of the aminotriazole-treated cells were cleared from circulation, matching the proportion of cells with reduced deformability as determined by a microfluidic ratchet device. After 24 hours, however, both the control and the remaining aminotrizole-treated cells were cleared at rates similar to endogenous RBCs, suggesting that clearance occurs in a deformability-dependent manner. Further research is needed to determine if low-deformability RBCs are cleared rapidly after transfusions in humans.
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