Red blood cells (RBC) transfusion is used to alleviate symptoms and prevent complications in anemic patients by restoring oxygen delivery to tissues.

In this study, we show in mice and human subjects that pre-transfusion Hb concentration negatively correlates with measures of transfusion efficacy. Exploration of the mechanistics of this observation in the mouse model showed that EPO signaling upregulates transfusion efficacy by downregulating transfused RBC clearance from circulation in the recipient.

From a clinical point of view, our results suggest that patients with acute blood loss are more likely to respond better than expected to RBC transfusion, and to respond better than patients with similar degrees of anemia but suppressed erythropoiesis. Casimir et al., 2023 .