In vivo maturation of cRBCs in the NOD/SCID mouse model. (A) Kinetics of CD71⁺ cells among CFSE⁺ cells in mouse blood after injection of purified CFSE⁺ cRBCs. Results are expressed as the mean ± SEM (n = 4). (B) CD71 expression on CFSE⁺ cells in 1 representative experiment. Quadrant statistics are given in each dot plot. The percentage of CFSE⁺ cells on days 1, 2, 3, and 5 was 2.65%, 19.2%, 20.5%, and 1.2%, respectively. (C) Kinetics of LDS expression on CFSE⁺ cells in 1 experiment. (D) Confocal microscopy images of CFSE⁺ cells before (top left) and after injection into mice (bottom) compared with native RBCs (top middle) and native reticulocytes (top right). On the bottom are front, profile, and side views of cells recovered 3 days after their injection. The cell diameter before and after 3 days injection was 11 μm and 7.5 μm, respectively. Magnification ×500. On day 3, sorted CFSE⁺ cells were colabeled with an anti-RhD antibody (solid histogram) or its isotype control (open histogram).