In Vivo Gene Therapy of Hemophilia B: Sustained Partial Correction in Factor IX-Deficient Dogs

Abstract

The liver represents a model organ for gene therapy. A method has been developed for hepatic gene transfer in vivo by the direct infusion of recombinant retroviral vectors into the portal vasculature, which results in the persistent expression of exogenous genes. To determine if these technologies are applicable for the treatment of hemophilia B patients, preclinical efficacy studies were done in a hemophilia B dog model. When the canine factor IX complementary DNA was transduced directly into the hepatocytes of affected dogs in vivo, the animals constitutively expressed low levels of canine factor IX for more than 5 months. Persistent expression of the clotting factor resulted in reductions of whole blood clotting and partial thromboplastin times of the treated animals. Thus, long-term treatment of hemophilia B patients may be feasible by direct hepatic gene therapy in vivo.

Role of paracellular junction complexes in baculovirus-mediated gene transfer to nondividing rat hepatocytes

“…Many different gene delivery methods are available including cationic lipid-based DNA transfection [44][45][46][47][48][49] and retroviral and adenoviral gene transfer vectors; [50][51][52][53][54][55] however, the use of these methods for hepatocytes has not been effective because hepatocytes do not divide, are highly susceptible to toxicity, and transfection efficiencies in hepatocytes are extremely low (HC Isom, unpublished data). 11 Previous studies have reported baculovirus-mediated gene delivery to primary hepatocytes.…”

Persistent expression of canine factor IX in hemophilia B canines

“…Although several different viral vectors have been used for the delivery of the FIX gene, vectors to date suffer from either low transduction 7 or exuberant immune response to the vector. 8 Recombinant adeno-associated virus (rAAV) has several features which are suited for FIX gene expression.…”

A preclinical model of hepatocyte gene transfer: the in vivo, in situ perfused rat liver

“…[16][17][18] In our laboratory, using an in vivo asanguineous model of nonoxygenated perfusion of the regenerating liver, we have demonstrated that rat 24 and dog livers 25 can be transduced after infusion of retroviruses into the portal vein. However, hepatocyte transduction rates were lower than 5% in rats and 1% in dogs.…”

“…[16][17][18] In the normal liver, adult hepatocytes are normally quiescent, highly differentiated cells. 19 They are not susceptible to retrovirus transduction that requires active DNA replication for integration into the host cell genome.…”