Corinna Lebherz

Intramyocardial gene therapy with naked DNA encoding vascular endothelial growth factor improves collateral flow to ischemic myocardium

Both VEGF protein and VEGF DNA in combination with an adenoviral vector have been shown to enhance collateral formation in a porcine model of chronic myocardial ischemia. We sought to determine whether direct intramyocardial injection of naked DNA encoding for VEGF could similarly improve myocardial perfusion. Initially, 23 nonischemic pigs received either 200 microg of plasmid DNA encoding beta-galactosidase (pCMVbeta, n = 11) or 500 microg of phVEGF165 (n = 12) into four separate sites in the myocardium via a small anterolateral thoracotomy incision in the fourth intercostal space. Two additional groups of pigs received an intramyocardial injection of either phVEGF165 (n = 6) or pCMVbeta (n = 7) 3 to 4 weeks after implantation of an ameroid constrictor around the left circumflex coronary artery. The injections caused no change in heart rate or blood pressure, and no ventricular arrhythmias or histologic evidence of inflammation. VEGF protein was detected by Western blot in VEGF-treated animals, with the strongest bands closest to the injection site. Plasma VEGF concentration (ELISA) increased from 3+/-2 to 27+/-13 pg/ml (p = 0.035) by day 4 after treatment. No increase in VEGF protein was noted in pCMVbeta-treated animals whereas these did stain positive for beta-Gal. Resting myocardial blood flow (colored microspheres) was significantly reduced in the ischemic versus nonischemic territory in control animals (1.07+/-0.05 versus 1.32+/-0.05; p < 0.05) but not VEGF-treated pigs (1.32+/-0.24 versus 1.13+/-0.12; p = NS). Maximal vasodilatation with adenosine significantly increased flow to the ischemic region in VEGF-treated pigs (2.16+/-0.57 versus 1.32+/-0.24; p < 0.05) but not controls (1.31+/-0.05 versus 1.17+/-0.06;p = NS). Collateral filling of the occluded circumflex artery improved in five of six VEGF-treated pigs (mean change in Rentrop score, +1.5). We conclude that direct intramyocardial transfection phVEGF165 is safe and capable of producing sufficient VEGF protein to enhance collateral formation and myocardial perfusion. This approach may offer an alternative therapy for patients with intractable myocardial ischemia not amenable to PTCA or CABG.

Novel AAV serotypes for improved ocular gene transfer

Some of the most successful gene therapy results have been obtained using recombinant viral vectors to treat animal models of inherited and acquired ocular diseases. Clinical trials using adenovirus vector systems have been initiated for two ocular diseases. Adeno‐associated viruses (AAVs) represent an attractive alternative to adenoviral vector systems as they enable stable and long‐term expression and can target a variety of different ocular cell types depending on the capsid serotype; recently clinical trails for congenital blindness was initiated with a vector‐based AAV serotype 2. High levels of retinal gene transfer have been achieved using vectors based on AAV serotypes 1, 2, 4 and 5. This report compares the gene transfer efficacy and stability of expression of vector systems based on three novel AAV serotypes: AAV7, 8, 9, with the established vectors AAV1, 2, 5. We show here that AAV7 and 8 enable superior long‐term transduction of retinal and also anterior chamber structures. Copyright

Gene therapy with novel adeno-associated virus vectors substantially diminishes atherosclerosis in a murine model of familial hypercholesterolemia.

Familial hypercholesterolemia is an inherited disease caused by mutations in the LDL receptor gene leading to severe hypercholesterolemia and atherosclerosis. The LDL receptor is predominantly expressed in the liver, making it a preferred target organ for somatic gene therapy. We recently isolated a new family of vectors based on adeno‐associated viruses (AAVs) isolated from nonhuman primates, which enable efficient and stable transgene expression following in vivo gene delivery to liver.

Gene transfer of wild-type apoA-I and apoA-I Milano reduce atherosclerosis to a similar extent

BackgroundThe atheroprotective effects of systemic delivery of either apolipoprotein A-I (wtApoA-I) or the naturally occurring mutant ApoA-I Milano (ApoA-IM) have been established in animal and human trials, but direct comparison studies evaluating the phenotype of ApoA-I or ApoAI-Milano knock-in mice or bone marrow transplantated animals with selectively ApoA-I or ApoAI-Milano transduced macrophages give conflicting results regarding the superior performance of either one. We therefore sought to compare the two forms of apoA-I using liver-directed somatic gene transfer in hypercholesterinemic mice – a model which is most adequately mimicking the clinical setting.Methods and resultsVectors based on AAV serotype 8 (AAV2.8) encoding wtApoA-I, ApoA-IM or green fluorescent protein (GFP) as control were constructed. LDL receptor deficient mice were fed a Western Diet. After 8 weeks the AAV vectors were injected, and 6 weeks later atherosclerotic lesion size was determined by aortic en face analysis. Expression of wtApoA-I reduced progression of atherosclerosis by 32% compared with control (p = 0.02) and of ApoA-IM by 24% (p = 0.04). There was no significant difference between the two forms of ApoA-I in inhibiting atherosclerosis progression.ConclusionLiver-directed AAV2.8-mediated gene transfer of wtApoA-I and ApoA-IM each significantly reduced atherosclerosis progression to a similar extent.

128. Use of chimeric adenoviral vectors to assess capsid neutralization determinants

In order to elucidate the relative importance of neutralizing determinants on each of the three major adenoviral capsid components, we have generated chimeric vectors where the hexon protein, or the fiber protein, or both hexon and fiber proteins of one serotype (Simian Adenovirus 24/Pan 7) have been replaced by those of another (Simian Adenovirus 23/Pan 6). The effect of each replacement was evaluated by neutralization assays and by attempted vector re-administration into mice. Both hexon and fiber were found to harbor neutralization epitopes although in vivo transduction was more severely affected by anti-hexon antibodies.