G1XCGD is an integrative, 3rd generation replication-defective, self-inactivating (SIN) HIV-derived Lentiviral (LV) vector, with a mutated Woodchuck hepatitis virus Posttranscriptional Regulatory Element (WPRE) sequence. (Figure 1) A LV vector derived from HIV-1 has been chosen with respect to LV natural properties: they are genetically stable, permanently integrate into the genome of transduced cells and provide long-term gene expression in vitro and in vivo. The transduction of Hematopoietic Stem Cells (HSC) with such LV can be achieved after limited pre-activation of the cells in short-term cultures with cytokines, in conditions that are compatible with the preservation of the self-renewing capacities of these cells. These properties make these LV suitable for ex-vivo gene therapy strategies using HSC.