Induced FVIII expression in megakaryocytes under the control of the α-IIb promoter. Murine FVIII^–/– bone marrow-derived hematopoietic stem cells were transduced with a lentiviral B domain-deleted cDNA construct for human FVIII (hFVIII) placed under the control of the integrin α-IIb promoter (2bF8) and the cells cultured in the presence of interleukin-3, interleukin-6, stem cell factor, thrombopoietin, and flt-3 ligand. Cells were immunostained for VWF (red) and FVIII (green). Untransduced cells only demonstrated VWF staining (A-D), whereas the 2bF8-transduced cells demonstrated FVIII immunostaining and colocalization of the FVIII with VWF (E-H and I-L). (Used with permission, with full details provided in J Thromb Haemostas. 2006;5:352-361.)