DRAG mice infused with human HSC develop human RBCs. A) Enumeration of human erythrocytes (hEry) and reticulocytes (hRet) in peripheral blood of DRAG mice by FACS using anti-human CD235a (glycophorin A) and Retic-Count (left panel). Controls are DRAG mice non-infused with HSCs (upper right panel) and human blood (lower right panel). B) Immunostaining of peripheral blood from HSC-infused DRAG mice (right) and human blood (left) with anti-human haemoglobin A. Arrow shows the presence of human RBCs. C) Frequency of human erythrocytes and reticulocytes in blood of HSC-infused DRAG mice (n = 10). Data represent mean ± SD of mice analysed individually. D) Bone marrow from HSC-infused (n = 3) and control (non-infused) (n = 7) DRAG mice was stained with anti-human CD235a and anti-mouse Ter-119 (upper left panels). Data represent mean ± SD of mice analysed individually. Staining with anti-human CD235a and anti-human CD71 showed that that the nucleated human RBC precursors expressed CD71 (upper right panel) (n = 1). Annexin-V and 7-AAD staining of human RBC precursors (CD235+) and non-erythroctyc precursors (CD235−) in the bone marrow of HSC-infused DRAG mice (lower panels) (n = 1).