Transient immune suppression to enhance in situ transduction efficiency of bone marrow cells after IO infusion of M-GFP-LVs. (A) Schematic of IO infusion of M-GFP-LV into BL6 mice pretreated with intraperitoneal injection of Dex (5 mg/kg, 4 times: −24, −4, 4, and 24 hours) or anti-CD8α mAb (4 mg/kg, 3 times: days −1, 4, and 11 or 5 times: days −1, 4, 11, 16, and 21) or combined drugs (Dex 4 times + anti-CD8α mAb 5 times). GFP expression in total bone marrow cells and HSCs (Lin⁻C-Kit⁺Sca1⁺) was measured by flow cytometry. (B) BL6 mice were pretreated with Dex after IO infusion of M-GFP-LV (8.8 × 10⁸ ifu per animal; n = 8) or treated with LVs only (n = 6) or sterile phosphate-buffered saline (PBS; 20 μL per animal; mock; n = 3). GFP expression in total bone marrow cells (left) and HSCs (right) was detected on day 7. (C) BL6 mice were pretreated with anti-CD8α mAb (3 times) after IO infusion of GFP-LV (8.8 × 10⁷ ifu per animal; n = 4) or treated with LV only (n = 4) or sterile PBS (20 μL per animal; mock; n = 3). GFP expression in total bone marrow cells (left) and HSCs (right) was detected on days 9, 30, and 63. (D) BL6 mice were pretreated with combined drugs after IO infusion of GFP-LV (3.6 × 10⁸ ifu per animal; n = 6) or treated with LVs only (n = 6) or sterile PBS (20 μL per animal; mock; n = 3). GFP expression in total bone marrow cells (left) and HSCs (right) was detected on days 7, 69, and 160. Data are expressed as mean ± standard deviation of the mean.