Amelioration of the anemia and RBC morphologic abnormalities of β-thalassemia after in vivo selection of mice transplanted with γ-globin/MGMT lentiviral vector-transduced cells. (A) Hb levels in the indicated groups of control, untreated and drug-treated animals, both before and after drug administration. Values are also shown for mice transplanted with mock-transduced β-thalassemic cells at 32 weeks after transplantation. Data represent the mean plus or minus SEM. Statistically significant differences are indicated by the P values, as determined by the Student t test. (B) Wright-Giemsa–stained blood smears are shown for a representative treated and untreated animal transplanted with V5-EF1-MGMT-transduced β-thalassemic cells, as indicated. Photomicrographs were generated using an Olympus microscope (model BX60F-3; Tokyo, Japan) and an Olympus digital camera (model DP71), 100×/1.3 NA oil objective.