Effect of MOI on transduction efficiency of lentivectors in human CD34

⁺ cells. A total of 10⁵CD34⁺ cells were transduced with various doses (1, 2, 5, 10, 20, and 50 × 10⁵ TU) of EF1α-GFP lentiviral vector, allowing MOIs ranging from 1 to 50. GFP expression was analyzed by flow cytometry after 4 days. (A) Data from one representative experiment are shown as frequency histograms of GFP fluorescence intensity versus cell number (events). Gates for GFP⁺ cells were set up according to untransfected cells (MOI 0). (B) Mean percentages of GFP⁺ cells obtained with MOIs of 0 to 10 and 10 to 50 are represented in the main panel and in the insert, respectively. These data are from 3 independent experiments for the 0-to-10 MOI range and from 2 independent experiments for the 10-to-50 MOI range. Error bars represent SD.