Our previous studies have demonstrated that platelet-targeted expression of FVIII or FIX under control of the platelet-specific αIIb promoter (2bF8 or 2bF9) via lentiviral gene delivery to hematopoietic stem cells (HSCs) can efficiently rescue the hemophilic bleeding phenotype and induce antigen-specific immune tolerance in hemophilia mouse models (31–33). This evidence concerns the gene F8 and hemophilia.