ABSTRACT
The retroviral vector system will continue to maintain its great potential and value for haemophilia gene therapy. The fact that no gene therapy protocol for either of the haemophilias has yet reached the clinical trial phase in Western nations indicates the substantial difficulties involved in developing durable gene therapy for haemophilias. Gene delivery methods can be categorized into two approaches: in vivo direct gene transfer and ex vivo gene transfer. The gene for factor IX is expressed in hepatocytes with a stringent tissue specificity. Ideally, therefore, this gene should be targeted to the liver to produce recombinant factor IX at its optimal level. Direct in vivo gene transfer approaches using non-viral vectors, such a vector DNA-ligand complex, have also been tested. The gene for factor IX is expressed in hepatocytes with a stringent tissue specificity. Ideally, therefore, this gene should be targeted to the liver to produce recombinant factor IX at its optimal level.
