Efficient transduction of bone marrow cells using GFP lentivirus. (A) Transduction of whole bone marrow with GFP lentivirus led to a titer-dependent increase in percentage of GFP-expressing cells. (B) Virus particle incorporation in bone marrow cells compared with HPRT of untransduced control cells and 24 hours after transduction with GFP-, H1.Empty-, or H1.shCCR2-lentivirus. Error bars in panels A and B represent SEM. (C,D) Fluorescence and light microscopic high-power field, respectively, of a white blood cell cytospin from control mice 6 weeks after transplantation of nontransduced bone marrow (original magnification, ×200). (E,F) White blood cells from mice that underwent transplantation with lentiviral GFP-transduced bone marrow show approximately 90% GFP-positive cells (panel E; original magnification, ×200), indicating that transplantation of lentivirus-transduced bone marrow results in sustained transgene expression by blood cells. Images were captured with a Leica DR-ME microscope equipped with a 20× objective lens and a 10× ocular lens, and Leica QWin software (Leica Imaging Systems) was used.