680. Non-Viral Transposon Mediated Gene Transfer of Human Factor VIII to Hemophilia A Mice*.

Hemophilia A is an X-linked genetic disorder disease resulting in quantitative or qualitative deficiencies in coagulation Factor VIII and the risk for sustained bleeding after trauma or injury. The disorder is an attractive candidate for treatment by gene transfer because only partial correction is required for clinically relevant effects. We are investigating the Sleeping Beauty transposon vector system to express FVIII, using a liver-specific mouse albumin enhancer and human alpha-1-antitrypsin promoter (Alb/HAAT) to direct human FVIII cDNA expression. Transgenes under investigation include B-domain deleted human FVIII (BDD-FVIII) and a FVIII cDNA engineered to include several asparagine-linked oligosaccharides within a short B-domain spacer (F226aa/N6, Pipe et al). Using E16 hemophilia A mice on a congenic C57/BL6 background, we are contrasting expression from these constructs following hydrodynamic tail vein injection. Transposon pT3-Alb/HAAT-BDD-FVIII resulted in plasma FVIII levels of 14 ng/ml 1 week post-injection which gradually declined to ∼4 ng/ml by 3 months. Preliminary results with transposon pT3-Alb/HAAT-F226aa/N6 demonstrate plasma FVIII levels of ∼15 ng/ml 1 month post-injection. No antibodies to hFVIII were detected in either group. These results indicate that a Sleeping Beauty transposon with a liver-specific promoter can direct human factor VIII expression in a mouse model of FVIII and attain partial correction of the deficient protein.Molecular Therapy (2006) 13, S262–S262; doi: 10.1016/j.ymthe.2006.08.757 [ABSTRACT FROM AUTHOR]