Proportion of SMEs at the end of storage correlates with 24-hour posttransfusion recovery in healthy human volunteers. (A) Quantification of SMEs upon storage of RBC concentrates in SAGM solution (n = 24) between days 3 and 42 (mean value in solid black line). Low (blue lines) and high proportions of SMEs (red lines) defined by proportions of SME < −1 SD (11%) and > +1 SD (38%) at the end of storage, respectively. (B) Representative normalized frequency plot for RBC concentrate at the end of storage in AS-3 showing a well-demarcated subpopulation of SMEs. Subpopulation of SMEs contains spherocytes, spheroechinocytes, and type III echinocytes (i), whereas normal-sized RBCs (ii) contain discocytes and type I and II echinocytes. (C) Correlation between 24-hour posttransfusion recovery and proportions of SMEs quantified by imaging flow cytometry at the end of storage (n = 31; P = .02; Spearman r = −0.42; r² = 0.24).