Efficiency of lentiviral transduction into SRCs. (A-H) Multilineage engraftment of human cells in the femur 3.5 weeks after intravenous transplantation into the NOD/SCID mice assessed by flow cytometry. The region 2 (R2) for the CD45⁺ cells (A) was set and used for the assessment of the CD19⁺ lymphoid (B, R4) and CD33⁺ myeloid (C, R5) cells. (D) The region R3 was set to define the CD45^–CD36⁺ erythroid population. The proportion of GFP-expressing cells was determined for lymphoid (F, R6), myeloid (G, R6) and erythroid (H, R7) lineages. (E) GFP expression levels for erythroid (dotted area), lymphoid (black line), and myeloid (gray line) cells are compared. (I) Proportion of GFP⁺ cells estimated by flow cytometry at day 4 of culture (▪). Kinetics of the contribution of gene-marked cells within the human grafts in the aspirated femur and at the end of experiment in BM, blood (PB), and spleen (Spl) following injection of noncultured cells (day 1, ▦) or cultured cells (day 4, □). Each bar represents the mean (± SE) data of 13 experiments and corresponds to 28 (day 1) and 33 (day 4) mice analyzed. (J) Proportion of the GFP⁺ cells within the human CD45⁺ grafts (▪) and percentage of GFP⁺ human colonies (▦) derived from the same grafts were assayed by flow cytometry. Presence of the provirus in the same colonies was determined by PCR (□). Each bar represents the mean (± SE) data of 4 experiments; 217 colonies obtained from 16 mice given transplants of either day 1 or day 4 cells were analyzed. (K) Percentage of GFP⁺ cells determined by flow cytometry (▦) and proportion of the same cells carrying the provirus analyzed by dot blot (□) in hematopoietic organs at 12 weeks after transplantation. Each bar represents the mean (± SE) data of 80 samples from 32 mice (8 experiments). Horizontal lines are the median value.