Requirements for baculoviruses for clinical gene therapy applications.

Baculoviruses have proven capacity for the production of recombinant proteins including virus-like particles and as viral vectors. Recent progress in preclinical studies suggest that baculoviruses have potential as new vectors for gene therapy but so far no clinical trials have been performed. To date, no specific guidelines for the use of baculoviruses as human gene therapy vectors exist but researchers can utilize existing guidelines made for other biological products. Because of the long history of research on baculoviruses, a lot of knowledge has been obtained that forms a good basis for the gene therapy development process. This article gives an overview of the current status of the application of baculovirus vectors in gene therapy and summarizes some of the challenges to overcome before the first clinical trials with baculoviruses can be accomplished.

Safety and feasibility of catheter-based local intracoronary vascular endothelial growth factor gene transfer in the prevention of postangioplasty and in-stent restenosis and in the treatment of chronic myocardial ischemia: phase II results of the Kuopio Angiogenesis Trial (KAT).

BACKGROUND: Catheter-based intracoronary vascular endothelial growth factor (VEGF) gene transfer is a potential treatment for coronary heart disease. However, only limited data are available about local VEGF gene transfer given during angioplasty (PTCA) and stenting. METHODS AND RESULTS: Patients with coronary heart disease (n=103; Canadian Cardiovascular Society class II to III; mean age, 58+/-6 years) were recruited in this randomized, placebo-controlled, double-blind phase II study. PTCA was performed with standard methods, followed by gene transfer with a perfusion-infusion catheter. Ninety percent of the patients were given stents; 37 patients received VEGF adenovirus (VEGF-Adv, 2x10(10) pfu), 28 patients received VEGF plasmid liposome (VEGF-P/L; 2000 microg of DNA with 2000 microL of DOTMA:DOPE [1:1 wt/wt]), and 38 control patients received Ringer's lactate. Follow-up time was 6 months. Gene transfer to coronary arteries was feasible and well tolerated. The overall clinical restenosis rate was 6%. In quantitative coronary angiography analysis, the minimal lumen diameter and percent of diameter stenosis did not significantly differ between the study groups. However, myocardial perfusion showed a significant improvement in the VEGF-Adv-treated patients after the 6-month follow-up. Some inflammatory responses were transiently present in the VEGF-Adv group, but no increases were detected in the incidences of serious adverse events in any of the study groups. CONCLUSIONS: Gene transfer with VEGF-Adv or VEGF-P/L during PTCA and stenting shows that (1) intracoronary gene transfer can be performed safely (no major gene transfer-related adverse effects were detected), (2) no differences in clinical restenosis rate or minimal lumen diameter were present after the 6-month follow-up, and (3) a significant increase was detected in myocardial perfusion in the VEGF-Adv-treated patients.

Autoantibodies against oxidized LDL are associated with severe chest pain attacks in patients with coronary heart disease.

Autoantibodies against oxidized low-density lipoprotein (oxLDL) predict the progression of atherosclerosis. Several studies have shown that oxLDL is present in atherosclerotic lesions and that several factors present in active atherosclerotic plaques can oxidatively modify LDL. Oxidation of LDL induces production of autoantibodies against oxLDL (oxLDLab) that can be measured using an EIA test. Our aim was to see whether oxLDLab are associated with severe chest pain attacks in coronary heart disease (CHD) patients. Patients having two- or three-vessel CHD, as assessed by coronary angiography, and their siblings were recruited into the study (n = 568, mean age 55.8 years, range 29.3-83.2 years). Nondiabetic patients having a history of severe chest pain attacks had significantly higher oxLDLab levels (0.611 +/- 0.56) than those who did not have a history of severe chest pain attacks (0.487 +/- 0.40) (p = 0.027), even though age, cholesterol level, body mass index, and blood pressure were similar in both groups. However, no difference was found in oxLDLab levels in diabetic patients with or without a history of severe chest pain attacks. Increased levels of oxLDL autoantibodies are associated with severe chest pain attacks in nondiabetic patients with CHD.

Antibodies against oxidized LDL and cardiolipin and mortality in patients with coronary heart disease.

The association between antibodies against oxidized LDL (oxLDL) and cardiolipin and the risks of death and cardiovascular disease events were evaluated in patients with established coronary heart disease (CHD). The patients (mean age: 61 years, range: 33-74 years) were participants in the EUROASPIRE study; 108 of them had undergone coronary artery bypass surgery, 106 had balloon angioplasty, 101 had a diagnosis of acute myocardial infarction (AMI), and 98 acute myocardial ischemia. Antibodies against oxLDL and cardiolipin were measured and incidence of CHD events and deaths were followed up for 5 years in 284 men and 129 women. During the follow-up 36 patients died and 21 had AMI. After adjustment for cardiovascular disease risk factors the relative risks (RR [95% confidence interval]) of death were 1 (reference), 2.50 (0.97-6.49) and 2.21 (0.85-5.80) in increasing tertile categories of anti-oxLDL antibody titers, respectively (P for trend 0.16). The risks of CHD-death or AMI combined were 1 (reference), 2.61 (1.02-6.65) and 1.06 (0.37-3.03) in increasing tertile categories of anticardiolipin antibody titers, respectively (P for trend 0.03). In conclusion, the results suggest that antibodies against oxLDL and cardiolipin are not major predictors of risks of death and CHD events in patients with established CHD.

Fibroblast growth factor 4 induces vascular permeability, angiogenesis and arteriogenesis in a rabbit hindlimb ischemia model.

Previous studies have shown that fibroblast growth factor (FGF)-1, FGF-2, and FGF-5 induce therapeutic angiogenesis. Here, we investigated the potential of FGF-4 for therapeutic neovascularization in comparison to vascular endothelial growth factor (VEGF), using adenoviral gene transfer in a novel rabbit hind limb ischemia model, with ischemia restricted to the calf. Magnetic resonance imaging and a modified Miles assay showed that both AdFGF-4 and AdVEGF given intramuscularly (i.m.) resulted in increases in vascular permeability and edema in transduced muscles 6 days after the gene transfer. In contrast, recombinant FGF-4 protein injected in the rabbit skin did not induce acute vascular permeability. Injections (i.m.) of AdFGF-4 and AdVEGF, but not intra-arterially administered AdVEGF, increased collateral growth, popliteal blood flow, and muscle perfusion compared with controls. The angiogenesis response consisted mainly of the enlargement of pre-existing vessels rather than an increase in capillary density. Adenoviral FGF-4 overexpression up-regulated endogenous VEGF, which may explain many of the effects thought to be specific for VEGF such as the increase in vascular permeability. This study demonstrates for the first time that FGF-4 induces vascular permeability, therapeutic angiogenesis, and arteriogenesis comparable to that of VEGF and could be useful for the treatment of peripheral vascular disease.

Adenovirus-mediated gene transfer of a secreted decoy human macrophage scavenger receptor (SR-AI) in LDL receptor knock-out mice.

Macrophage scavenger receptors (MSR) play an important role in the pathogenesis of atherosclerosis. Therefore, modulation of MSR activity could have a beneficial effect on atherogenesis. One way to antagonize the function of a cell surface scavenger receptor is to use a soluble decoy receptor. We have constructed a soluble, chimaeric fusion protein that consists of the bovine growth hormone signal sequence and the human MSR AI extracellular domains. This secreted decoy MSR (sMSR) was cloned into an adenoviral vector and the recombinant adenoviruses were used for gene transfer experiments in vivo. We have previously shown that the secreted MSR inhibits degradation of acetylated LDL and oxidized LDL in mouse macrophages and reduces foam cell formation in vitro. We now report that in comparison to LacZ transfected control mice gene transfer with sMSR adenoviruses via tail vein injection (1 x 10(9) pfu) reduces atherosclerotic lesion area in hypercholesterolemic LDL receptor knock-out mice by 14 (P<0.05) and 19% (P=0.01), 4 and 6 weeks after the gene transfer. However, a statistically significant difference in the aortic root atherosclerosis was not detected. This is the first demonstration that the decoy sMSR can affect atherogenesis in mice after recombinant adenovirus-mediated gene transfer. Even though the achieved reduction in atherosclerosis was relatively modest the results suggest that sMSR may offer new strategies for the treatment of atherosclerosis and lipid accumulation in the vessel wall.

Adeno-associated virus-mediated gene transfer of a secreted decoy human macrophage scavenger receptor reduces atherosclerotic lesion formation in LDL receptor knockout mice.

Macrophage scavenger receptors (MSR) promote atherosclerotic lesion formation, and modulation of MSR activity has been shown to influence atherosclerosis. Soluble receptors are effective in inhibiting receptor-mediated functions in various diseases. We have generated a secreted macrophage scavenger receptor (sMSR) that consists of the bovine growth hormone signal sequence and the human MSR A I extracellular domains. sMSR reduces degradation of atherogenic modified low-density lipoproteins and monocyte/macrophage adhesion on endothelial cells in vitro. To test long-term effects of sMSR, atherosclerosis-susceptible LDLR knockout mice were transduced via the tail vein with an adeno-associated virus (AAV) expressing sMSR or control enhanced green fluorescent protein (EGFP), and a Western-type diet was started. Gene transfer caused a temporary elevation in alkaline phosphatase and aspartate amino transferase values without a change in C-reactive protein. sMSR protein was detected in the plasma of the transduced mice by a specific ELISA 6 months after the gene transfer. AAV-mediated sMSR gene transfer reduced atherosclerotic lesion area in the aorta by 21% (P < 0.05) compared to EGFP-transduced control mice. Even though eradication of established disease was not possible, atherosclerotic lesion formation could be modified using AAV-mediated gene transfer of the decoy sMSR.

Evaluation of angiogenesis and side effects in ischemic rabbit hindlimbs after intramuscular injection of adenoviral vectors encoding VEGF and LacZ.

BACKGROUND: Recent studies have suggested the therapeutic potential of vascular endothelial growth factor (VEGF) gene therapy in ischemic skeletal muscle. However, only limited information is available about the effects of VEGF gene therapy in different regions of ischemic limbs, effects of control adenoviruses, and biodistribution of the transgenes after intramuscular (i.m.) administration. Here we studied angiogenesis and side effects of adenovirus-mediated VEGF and beta-galactosidase (LacZ) gene transfers in ischemic rabbit hindlimbs. METHODS AND RESULTS: Ten days after induction of ischemia, rabbits were treated with i.m. injections of saline, LacZ adenovirus (AdLacZ; 2x10(10) pfu) or adenovirus encoding mouse VEGF(164) (AdVEGF; 2x10(10) pfu). In rabbits treated with AdVEGF an increase in serum VEGF(164) levels was detected by ELISA three and seven days after the gene transfer. 30 days after the gene transfer a positive effect on capillary density was observed in the thigh region both in rabbits treated with AdVEGF and AdLacZ compared with animals that received saline. On the other hand, AdVEGF and AdLacZ gene transfers had no effect on the capillary density in the calf region on day 30. A positive correlation between the capillary density and the number of collateral arteries was observed in the thigh. Hindlimb and testis edema and excess non-physiological growth of capillaries were detected as adverse effects of the AdVEGF gene therapy. Biodistribution analysis showed that the transgene was present not only in the target muscle, but also in ectopic tissues seven days after i.m. gene transfer. CONCLUSIONS: The results suggest that a high dose of adenoviral vector encoding either AdVEGF or AdLacZ induces angiogenesis in the rabbit hindlimb ischemia model; i.m. injection of adenovirus leads to the transfection of ectopic organs; and AdVEGF gene transfer induces edema in ischemic skeletal muscle.