Ex vivo gene therapy using LV.pF8.FVIII. (A) FACS analysis for hD45 showing human chimerism after LV.pF8.FVIII-CD34⁺ transplant in NSG-HA mice for up to 3 months. aPTT (B) and bleeding (C) assays confirm therapeutic activity of FVIII and phenotypic correction in mice transplanted with LV.pF8.FVIII-hCD34⁺. (D) aPTT showing FVIII activity rescue after Lin⁻ transduced cell transplantation. (E) ELISA assay demonstrates the absence of anti-FVIII antibodies in Lin⁻ transplanted mice. (F) Bleeding assay in mice transplanted with transduced hCD34⁺ or murine Lin⁻ cells demonstrate the achievement of phenotypic correction in all treated mice. *P ≤ .0001.