Highly efficient liposome-mediated gene transfer of inducible nitric oxide synthase in vivo and in vitro in vascular smooth muscle cells

Nanocarriers for nitric oxide delivery

Nitric oxide (NO) is a promising pharmaceutical agent that has vasodilative, antibacterial, and tumoricidal effects. To study the complex and wide-ranging roles of NO and to facilitate its therapeutic use, a great number of synthetic compounds (e.g., nitrosothiols, nitrosohydroxyamines, N-diazeniumdiolates, and nitrosyl metal complexes) have been developed to chemically stabilize and release NO in a controlled manner. Although NO is currently being exploited in many biomedical applications, its use is limited by several factors, including a short half-life, instability during storage, and potential toxicity. Additionally, efficient methods of both localized and systemic in vivo delivery and dose control are needed. One strategy for addressing these limitations and thus increasing the utility of NO donors is based on nanotechnology.

Vascular cells contribute to atherosclerosis by cytokine- and innate-immunity-related inflammatory mechanisms

Cardiovascular diseases are the human diseases with the highest death rate and atherosclerosis is one of the major underlying causes of cardiovascular diseases. Inflammatory and innate immune mechanisms, employing monocytes, innate receptors, innate cytokines, or chemokines are suggested to be involved in atherogenesis. Among the inflammatory pathways the cytokines are central players. Plasma levels of cytokines and related proteins, such as CRP, have been investigated in cardiovascular patients, tissue mRNA expression was analyzed and correlations to vascular diseases established. Consistent with these findings the generation of cytokine-deficient animals has provided direct evidence for a role of cytokines in atherosclerosis. In vitro cell culture experiments further support the suggestion that cytokines and other innate mechanisms contribute to atherogenesis. Among the initiation pathways of atherogenesis are innate mechanisms, such as toll-like-receptors (TLRs), including the endotoxin receptor TLR4. On the other hand, innate cytokines, such as IL-1 or TNF, or even autoimmune triggers may activate the cells. Cytokines potently activate multiple functions relevant to maintain or spoil homeostasis within the vessel wall. Vascular cells, not least smooth muscle cells, can actively contribute to the inflammatory cytokine-dependent network in the blood vessel wall by: (i) production of cytokines; (ii) response to these potent cell activators; and (iii) cytokine-mediated interaction with invading cells, such as monocytes, T-cells, or mast cells. Activation of these pathways results in accumulation of cells and increased LDL- and ECM-deposition which may serve as an 'immunovascular memory' resulting in an ever-growing response to subsequent invasions. Thus, vascular cells may potently contribute to the inflammatory pathways involved in development and acceleration of atherosclerosis.

Intravenous injection of phagocytes transfected ex vivo with FGF4 DNA/biodegradable gelatin complex promotes angiogenesis in a rat myocardial ischemia/reperfusion injury model

Conventional gene therapies still present difficulties due to poor tissue-targeting, invasiveness of delivery, method, or the use of viral vectors. To establish the feasibility of using non-virally ex vivo transfected phagocytes to promote angiogenesis in ischemic myocardium, gene-transfection into isolated phagocytes was performed by culture with positively charged gelatin impregnated with plasmid DNA. A high rate of gene transfection was achieved in rat macrophages and human monocytes, but not in mouse fibroblasts. The efficiency was 68 +/- 11% in rat macrophages and 78 +/- 8% in human monocytes. Intravenously injected phagocytes accumulated predominantly in ischemic tissue (13 +/- 8%) and spleen (84 +/- 6%), but negligibly in other organs in rodents. The efficiency of accumulation in the target ischemic tissue reached more than 86% on direct local tissue injection. In a rat model of myocardial ischemia-reperfusion, intravenous injection of fibroblast growth factor 4 (FGF4)-gene-transfected macrophages significantly increased regional blood flow in the ischemic myocardium (78 +/- 7.1 % in terms of flow ratio of ischemic/non-ischemic myocardium) compared with intravenous administration of saline (36 +/- 11%) or nontransfected macrophages (42 +/- 12 %), or intramuscular administration of naked DNA encoding FGF4 (75 +/- 18 %). Enhanced angiogenesis in the ischemic tissue we confirmed histologically. Similarly, intravenous injection of FGF4-gene-transfected monocytes enhanced regional blood flow in an ischemic hindlimb model in mice (93 +/- 22 %), being superior to the three other treatments described above (38 +/- 12, 39 +/- 15, and 55 +/- 12%, respectively). Phagocytes transfected ex vivo with FGF4 DNA/gelatin promoted angiogenesis. This approach might have potential for non-viral angiogenic gene therapy.

Transfection efficiency and cytotoxicity of nonviral gene transfer reagents in human smooth muscle and endothelial cells

PURPOSE

Evaluation of a nonviral transfection reagent with respect to efficient gene transfer into primary human vascular cells.

METHODS

Complexes consisting of seven commercially available transfection reagents (DAC-30, DC-30, Lipofectin, LipofectAMINE PLUS, Effectene, FuGene 6 and Superfect) and EGFP encoding plasmid DNA were studied. The in vitro transfection efficiency and cytotoxicity in human aorta smooth muscle cells (HASMCs) and endothelial cells (HAECs) and rat smooth muscle cells (A-10 SMCs) were assayed in the presence of serum using flow cytometric analysis and ATP-quantitation assay, respectively.

RESULTS

Human primary cells were transfected less efficiently compared to the rat smooth muscle cell line. Transfection efficiency depended on the type of reagent, the reagent/DNA ratio, and, most importantly, on the cell type used. Determination of cytotoxicity showed that the effects of transfection on cell viability did not significantly differ from one another depending on the cell type. The exception to this was Superfect, which obviously reduced cell viability in all cell types.

CONCLUSIONS

Our experiments showed that DAC-30 is the preferred transfection reagent for HASMCs and HAECs, exhibiting an improved efficiency combined with an acceptable cytotoxicity. Therefore, it might offer a therapeutic option for the treatment of cardiovascular disease and prove suitable for further drug development.

Optimization of in vitro vascular cell transfection with non-viral vectors for in vivo applications

BACKGROUND

Syngeneic vascular cells are interesting tools for indirect gene therapy in the cardiovascular system. This study aims to optimize transfection conditions of primary cultures of vascular smooth muscle cells (VSMCs) using different non-viral vectors and zinc as an adjuvant and to implant these transfected cells in vivo.

METHODS

Non-liposomal cationic vectors (FuGene 6), polyethylenimines (ExGen 500), and histidylated polylysine (HPL) were used as non-viral vectors in vitro with secreted alkaline phosphatase (SEAP) as reporter gene. Transfection efficiency was compared in cultured rat, rabbit and human VSMCs and fibroblasts. Zinc chloride (ZnCl2) was added to optimize transfection of rat VSMCs in vitro which were then seeded in vivo.

RESULTS

Much higher SEAP levels were obtained in rabbit cells with FuGene 6 (p <0.0001) at day 2 than in equivalent rat and human cells. Rat VSMCs transfected in vitro with FuGene 6 and ExGen 500 expressed higher SEAP levels than with HPL. In rat VSMCs, SEAP secretion was more than doubled by addition of 250 microM ZnCl2 (p <0.0001) for all vectors. Seeding of syngeneic VSMCs transfected under optimized conditions (FuGene 6/pcDNA3-SEAP +250 microM ZnCl2) into healthy Lewis rats using various routes or into post-infarct myocardial scar resulted in a peak of SEAP expression at day 2 and detectable activity in the plasma for at least 8 days.

CONCLUSIONS

FuGene 6 is an efficient non-viral transfection reagent for gene transfer in somatic smooth muscle cells in vitro and ZnCl2 enhances its efficiency. This increased expression of the transgene product is maintained after seeding in vivo.

Cationic lipid-mediated transfection of bovine aortic endothelial cells inhibits their attachment

The need for a small-diameter vascular graft for coronary artery and peripheral vascular replacement is great and is projected to increase as the population ages. Synthetic small-diameter vascular grafts fail because of acute thrombosis or chronic intimal hyperplasia leading to restenosis. Endothelial cell seeding has been attempted with limited success in the femoral artery by Zilla and others. However, patency rates have not increased sufficiently to justify large clinical trials. Genetic engineering of endothelial cells before seeding has been proposed to encourage endothelial cell phenotypes that would predispose the graft to patency. In this study, we investigate the effect cationic lipid-mediated transfection of endothelial cells with respect to their attachment to a potential graft material, Fluoropassiv (Vascutek). Liposomal transfection was optimized for maximum gene expression. We report that transfection decreases the ability of bovine aortic endothelial cells to attach by approximately 100% as compared with nontransfected control over 18 h. Further, when placed under physiologic shear conditions, this difference is sustained. The effects of gene transfer on endothelial cell adhesion must be included as an important optimization criterion along with gene expression for engineered endothelial cell-seeding applications.

Reduction of BCNU toxicity to lung cells by high-level expression of O(6)-methylguanine-DNA methyltransferase

1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU) is an important cause of pulmonary toxicity. BCNU alkylates DNA at the O(6) position of guanine. O(6)-methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein that removes alkyl groups from the O(6) position of guanine. To determine whether overexpression of MGMT in a lung cell reduces BCNU toxicity, the MGMT gene was transfected into A549 cells, a lung epithelial cell line. Transfected A549 cell populations demonstrated high levels of MGMT RNA, MGMT protein, and DNA repair activity. The overexpression of MGMT in lung epithelial cells provided protection from the cytotoxic effects of BCNU. Control A549 cells incubated with 100 microM BCNU had a cell survival rate of 12.5 +/- 1.2%; however, A549 cells overexpressing MGMT had a survival rate of 71.8 +/- 2.7% (P < 0.001). We also demonstrated successful transfection of MGMT into human pulmonary artery endothelial cells and a primary culture of rat type II alveolar epithelial cells with overexpression of MGMT, resulting in significant protection from BCNU toxicity. These data suggest that overexpression of DNA repair proteins such as MGMT in lung cells may protect the lung cells from cytotoxic effects of cancer chemotherapy drugs such as BCNU.