F8 and hemophilia A: This new information, which supports previous reports in human cultured ECs [11–13] and more recent findings in mice, [19,20] may lead to improved therapy for hemophilia A. Recognition that FVIII is normally synthesized in human ECs and stored in their WPBs for regulated secretion (along with VWF) indicates that these organelles may ultimately become the precise, most effective physiological targets for human F8 gene delivery.