Transplantation of healthy BM and phenotypic correction in hemophilia A. (A) Flow cytometry of blood cells showing BM chimerism was similar 4 months after 2 × 106 to 10 × 106 GFP+ BM cells were transplanted in hemophilia mice. (B) FVIII mRNA expression in BM by single-step RT-PCR: lanes 1-13, BM-recipient hemophilia mice 3 to 6 months after transplantation of 2 × 106 whole BM cells; lane marked (+), GFP+ mouse BM; lane marked (−), hemophilia mouse liver; lane marked (W), PCR mix alone. β-actin RNA was loading control. (C) Percentage of therapeutic correction in 74 consecutive hemophilia mice with plasma FVIII activity (≥ 1% or 0.01 IU/mL of human FVIII standard) or without FVIII activity after BM transplants, including subgroups with 2 × 106 BM cells (n = 42) or 10 × 106 BM cells (n = 32). (D) Plasma FVIII activity levels with FTGT in hemophilia mice shown in preceding panel indicated less correction after 2 × 106 versus 10 × 106 BM cells (P < .001; t test; 100% mouse plasma FVIII activity corresponded to 1.02 IU/mL of human FVIII standard).
