Our previous studies have demonstrated that targeting coagulation factor VIII (FVIII) expression to platelets under the control of the platelet-specific αIIb promoter (2bF8) results in the storage of FVIII in platelet α-granules and that platelet-derived FVIII can effectively induce antigen-specific immune tolerance in hemophilia A mice even with pre-existing anti-FVIII immunity (23–28). Here, F8 is linked to hemophilia A.