Human and porcine FVIII expressed in mammalian cells with or without parts of the B domain27 have very similar biochemical and hemostatic properties to plasma derived (pd) FVIII and a similar pharmacokinetic profile2 when used for treatment of Hemophilia A. Human FVIII lacking the B domain (hFVIII) shows much less structural heterogeneity than pdFVIII and is more suitable for biochemical, biophysical and structural studies28. Here, F8 is linked to hemophilia A.