ADA-transduced bone marrow cells (San Raffaele Telethon Institute for Gene Therapy)

Bone marrow was depleted from red blood cells (RBC) by RBC lysis. The remaining cells were cultured (10⁶/mL) for 24 hours in StemSpan serum-free expansion medium in the presence of murine stem cell factor (50ng/mL; SCF), human Flt3 ligand (10ng/mL ; Flt3-L), human interleukin-6 (20ng/mL; IL-6), murine IL-3 (10ng/mL), murine thrombopoietin (20ng/mL; Tpo), polybrene (4μg/mL), and PGK-ADA (0.4μg of viral p24 per 10⁶ cells, corresponding to a multiplicity of infection [MOI] of 4–12).