ABSTRACT
Familial hypercholesterolemia (FH) is an inherited disease of lipoprotein metabolism caused by a defect in the LDL receptor (LDLR) leading to severe hypercholesterolemia, and associated with an increased risk of coronary heart disease and myocardial infarction. We have developed a gene therapy protocol for FH using AAV2, AAV9 and lentiviral vectors and tested safety and efficacy in LDL receptor deficient Watanabe Heritable Hyperlipidemic rabbits. We show that LV-LDLR produced a significant long-lasting decrease in total serum cholesterol whereas AAV9-LDLR resulted only in a transient decrease and AAV2-LDLR failed to reduce serum cholesterol levels. A significant pathological side effect, bile-duct proliferation, was seen in the liver of AAV2-LDLR rabbits associated with an increased expression of Cyr61 matricellular protein. Special attention should be given to liver changes in gene therapy applications when genes affecting cholesterol and lipoprotein metabolism are used for therapy.
Subject(s)
Bile Ducts/metabolism , Gene Transfer Techniques , Genetic Vectors/genetics , Liver/metabolism , Parvovirinae/genetics , Receptors, LDL/genetics , Animals , Bile Ducts/pathology , Biomarkers , Cholesterol/metabolism , Dependovirus , Gene Expression , Gene Transfer Techniques/adverse effects , Immunohistochemistry , Lipid Metabolism , Liver/pathology , RabbitsABSTRACT
Lentiviral vectors encoding rabbit low-density lipoprotein receptor (LDLR) or green fluorescent protein (GFP) under the control of a liver-specific promoter (LSP) were used for intraportal gene transfer into the liver of hypercholesterolemic LDLR-deficient Watanabe Heritable Hyperlipidemic rabbits. In vitro cell culture analysis demonstrated functionality of the LSP-LDLR vector in mediating increased degradation of LDL in transduced liver cells. Twenty-five rabbits were each injected with 1 x 10(9) infectious virus particles into the portal vein. Liver biopsy samples were collected 4 weeks after the gene transfer and the rabbits were followed up for 2 years. Histological and RT-PCR analyses showed the expression of GFP and LDLR transgenes in the biopsy samples. Clinical chemistry and histological analyses revealed normal liver function and morphology during the 2-year follow-up with no safety issues. LSP-LDLR-treated rabbits demonstrated an average of 14 +/- 7% decrease in serum cholesterol levels during the first 4 weeks, 44 +/- 8% decrease at 1 year, and 34 +/- 10% decrease at the 2-year time point compared to the control rabbits. This study demonstrates the safety and potential benefits of the third-generation liver-specific lentiviral vectors in the treatment of familial hypercholesterolemia using direct intraportal liver gene therapy without the need for liver resection.
Subject(s)
Cholesterol/blood , Gene Transfer Techniques , Genetic Therapy/methods , Receptors, LDL/genetics , Animals , Cholesterol/metabolism , Disease Models, Animal , Genetic Vectors , Immunohistochemistry , Lentivirus/genetics , Liver/metabolism , Liver/pathology , Models, Genetic , Polymerase Chain Reaction , Promoter Regions, Genetic , Rabbits , Reverse Transcriptase Polymerase Chain Reaction , Time Factors , TransgenesABSTRACT
We have developed an ex vivo gene transfer technique to rabbit arterial wall using autologous smooth muscle cells (SMCs). SMCs were harvested from rabbit ear artery, transduced in vitro with vesicular stomatitis virus G-glycoprotein pseudotyped retrovirus or feline immunodeficiency virus (FIV) and returned to the adventitial surface of the carotid artery using a periadventitial silicone collar or collagen sheet placed around the artery. Beta-galactosidase (lacZ) and human apolipoprotein E3 (apoE3) cDNAs were used as transgenes. After retrovirus-mediated gene transfer of lacZ the selected cells implanted with high efficiency and expressed lacZ marker gene at a very high level 7 and 14 days after the operation. The level of lacZ expression decreased thereafter but was still detectable 12 weeks after the gene transfer, and was exclusively localized to the site of cell implantation inside the collar. Utilizing FIV vector expressing apoE3, low levels of apoE were measured from serum collected from a low-density lipoprotein receptor deficient Watanabe heritable hyperlipidemic rabbits 1 month after the gene transfer. The physiological effect of apoE expression was detected as transiently elevated serum cholesterol levels. The results indicate that the model can be used for high efficiency local gene transfer in arteries, e.g. during vascular surgery. The model is also valuable for studying expression, stability and safety of new gene transfer vectors and their expression products in vivo.
