In vivo HSC transduction with HDAd-LCR-ET3/mgmt in hCD46-transgenic “healthy” mice. (A) Vector structure. See description of Figure 1A. The HDAd-LCR-ET3/mgmt vector contains the cDNA of ET3 instead of the GFP gene. (B) The treatment regimen is the same as shown in Figure 1B. Instead of HDAd-LCR-GFP, the factor VIII/ET3 expressing vector HDAd-LCR-ET3/mgtm was used. (C) Plasma concentrations of ET3 measured by ELISA. Each symbol is an individual animal. The values are expressed relative to FVIII levels in human plasma. Therefore, 100% (= 2180 ng/mL) would correspond to 1 U/mL. The dotted red line indicates 5% of physiological levels, which would correspond to a mild hemophilia A in patients and is therefore considered a therapeutic target.⁷  (D) Representative profiles of plasma anti-ET3 antibodies. Animals fall into the 4 groups indicated by corresponding colored arrows on the right side of the last panel in C. (E) ET3 mRNA levels measured by qRT-PCR relative to mouse mRPL10 mRNA levels. (F) Integrated ET3 cDNA copies per cell (VCN) in CFU. Bone marrow Lin⁻ cells (pooled from 3 mice) were isolated at week 24 and plated for CFU assay. Individual colonies were picked, and the VCN was measured. Each symbol is an individual colony. In vivo HSC transduced mice were kept alive without side effects for 24 weeks.