Differential mitochondrial mass, membrane potential, and superoxide production in RBCs from HCs and patients who were SCD-Baseline (n = 4 each). (A) HCs display a slight increase in the percentage of mature RBCs compared with patients with SCD, but the difference is not significant. (B) Immature RBCs (reticulocytes) were significantly higher in SCD patients. Mature RBCs from SCD patients showed a significant increase in mitochondrial mass (quantified as the fluorescent intensity of MTG) (C), the amount of mitochondrial superoxide (estimated with MitoSOX Red) (E), and mitochondrial membrane potential (quantified with MTDR) (G) compared with mature RBCs from HCs but there was no significant difference in mitochondrial mass (D), superoxide levels (F), or mitochondrial membrane potential (H) between SCD and HC reticulocytes. Errors bars represent the sample mean ± SD. *P < .05, Student t test.