We took advantage of the large cloning capacity of lentiviral vectors (LV) and their high transduction efficiencies, safety, and long-term expression in the CNS to optimize the CRISPR/Cas9 system delivery (Cartier et al., 2009xHematopoietic stem cell gene therapy with a lentiviral vector in X-linked adrenoleukodystrophy. Cartier, N., Hacein-Bey-Abina, S., Bartholomae, C.C., Veres, G., Schmidt, M., Kutschera, I., Vidaud, M., Abel, U., Dal-Cortivo, L., Caccavelli, L. et al. Science.