Transient Increase in Intrahepatic Pressure Mediates Successful Treatment of the Gunn Rat with Reduced Doses of Lentiviral Vector

Abstract

Lentiviral vectors can stably transduce hepatocytes and are promising tools for gene therapy of hepatic diseases. Although hepatocytes are accessible to blood-borne viral vectors through fenestrations of the hepatic endothelium, improved liver transduction after delivery of vectors to the blood stream is needed. As the normal endothelial fenestration and lentiviral vectors are similar in size (150 nm), we hypothesized that a transient increase in hepatic blood pressure may enhance in vivo gene transfer to hepatocytes. We designed a simple surgical procedure, by which the liver is temporarily excluded from blood flow. Lentiviral vectors were injected in a large volume to increase intrahepatic pressure. We demonstrated that in the Gunn rat, a model of Crigler-Najjar disease, the administration of low vector doses (corresponding to a multiplicity of infection of 0.2) by this procedure resulted in therapeutic correction of hyperbilirubinemia, without toxicity. The correction was sustained for 10 months (end of study). The same vector amounts yielded only partial correction after intraportal delivery. We believe that this new and clinically applicable strategy may broaden the range of genetic liver diseases accessible to gene therapy.

Liver Gene Therapy Approaches for Acute Intermittent Porphyria: Metabolic Correction and Immunological Hurdles

“…The endothelium of hepatic sinusoids displays 100 nm wide fenestrations that allow macromolecules such as viral vector particles to cross the vessel wall and reach hepatocytes. 41 The vectors used for gene transfer to the liver have a particle size equal to or less than the diameter of these fenestrae. 42 Vectors derived from AAV are those with the smallest particle size (20-25 nm) and retroviral or lentiviral vector are the largest (100 nm).…”

“…42 Vectors derived from AAV are those with the smallest particle size (20-25 nm) and retroviral or lentiviral vector are the largest (100 nm). 41 The adenoviral-derived vectors exhibit a particle size of about 70 nm. To date, the preferred gene therapy vectors in the context of the liver are the recombinant adenoviral and AAV vectors.…”

“…Lentiviral vectors which have had success in long-term correction of immunodeficiencies, 43 transduce hepatocytes inefficiently as compared to non-parenchymal cells. 41 …”