RDTR/SCFHA-displaying LVs allow in vivo gene transfer into immature hCD34⁺ cells in humanized mice. Newborn Balbc rag2^−/−γc^−/− mice received sublethal irradiation (2 × 1.5 Gy) and then 2 × 10⁵ hCD34⁺ CB cells were injected into the fetal liver at day 2 to 4 after birth. After 13 weeks of reconstitution, RDTR/SCFHA-LVs were injected into both femurs of the humanized mice. Two to 3 weeks after injection, the mice were killed and the transduction of the different cell lineages in the BM was analyzed (A-D). The percentage of transduced human cells (hCD45⁺GFP⁺) is shown for 3 different injected animals listed in Table 2 (A). In panel B, transduction (GFP⁺) of immature progenitors (hCD34⁺), myeloid progenitors (hCD13⁺), monocytes (hCD14⁺), and pre- and pro-B cells (hCD19⁺) in the BM was analyzed by FACS. (C) Transduction in different BM subpopulations by CD34/CD19 double staining. Transduction is shown for very immature, nonlineage-committed CD34⁺ cells (CD34⁺CD19⁻), for pre- and pro-B cells (CD34⁺CD19⁺) and further differentiated B cells (CD34⁻CD19⁺). In panel D, transduction of immature B cells (CD19⁺CD20⁻) and of mature B cells (CD19⁺CD20⁺) are presented in the dot blots.