Gene Therapy for Cardiovascular Disease

The last decade has seen substantial advances in the development of gene therapy strategies and vector technology for the treatment of a diverse number of diseases, with a view to translating the successes observed in animal models into the clinic. Perhaps the overwhelming drive for the increase in vascular gene transfer studies is the current lack of successful long-term pharmacological treatments for complex cardiovascular diseases. The increase in cardiovascular disease to epidemic proportions has also led many to conclude that drug therapy may have reached a plateau in its efficacy and that gene therapy may represent a realistic solution to a long-term problem. Here, we discuss gene delivery approaches and target diseases

Efficient transduction of primary vascular cells by the rare adenovirus serotype 49 vector

Neointima formation and vascular remodelling through vascular smooth muscle cell migration and proliferation can limit the long term success of coronary interventions, for example in coronary artery bypass grafting (CABG). Ex vivo gene therapy has the potential to reduce unnecessary cell proliferation and limit neointima formation in vascular pathologies. To date the species C adenovirus serotype 5 (Ad5) has been commonly used for pre-clinical gene therapy, however its suitability is potentially limited by relatively poor tropism for vascular cells and high levels of pre-existing immunity in the population. To avoid these limitations, novel species of adenovirus are being tested; here we investigate the potential of adenovirus 49 (Ad49) for use in gene therapy. Transduction of primary human vascular cells by a range of adenovirus serotypes was assessed; Ad49 demonstrated highest transduction of both vascular smooth muscle and endothelial cells. Gene transfer with Ad49 in vascular smooth muscle and endothelial cells was possible following short exposure times (*lt;1hr) and with low MOI which is clinically relevant. Ex vivo delivery to surplus CABG tissue showed efficient gene transfer with Ad49, consistent with the in vitro findings. Luminal infusion of Ad49GFP into intact CABG samples ex vivo resulted in efficient vessel transduction. In addition, no seroprevelance rates to Ad49 were observed in a Scottish cohort of patients from cardiovascular clinics, thus circumventing issues with pre-existing immunity. Our results show Ad49 has tropism for vascular cells in vitro and ex vivo and demonstrate Ad49 may be an improved vector for local vascular gene therapy compared to current alternatives

Growth factors and experimental arterial grafts

Background: The production of growth factors from several experimental arterial conduits was determined. Methods: We implanted 105 experimental arterial grafts that were 1 cm long in the abdominal aorta of Lewis rats (average weight, 250 g). Five different types of grafts were analyzed: arterial isografts, vein grafts, arterial allografts, and polytetrafluoroethylene (PTFE) grafts with normal or decreased compliance. Animals were killed humanely 4 weeks after surgery and the production of platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), transforming growth factor-b, tumor necrosis factor-a, and interleukin-1 was analyzed. Results: Myointimal hyperplasia (MH) was evident in vein grafts, arterial allografts, and PTFE grafts, but not in arterial isografts. Growth factor production was increased for grafts prone to develop MH like vein, PTFE grafts, and arterial allografts. PDGF and bFGF were increased significantly for PTFE and vein grafts, but not for arterial allografts. The importance of bFGF and PGDF was confirmed by the capability of antibody to PDGF and to bFGF to reduce the mitogenic activity of smooth muscle cells, in vivo and in vitro, for PTFE and vein grafts, but not for arterial allografts, in which a predominant role was played by interleukin-1 and tumor necrosis factor-a. Conclusions: Agents able to neutralize this increased production of growth factors, either directly or by competition with their receptors, can prevent MH formation. (J Vasc Surg 2016;64:1444-9.) Clinical Relevance: Arterial grafts release growth factors, which can lead to myointimal hyperplasia formation and atherosclerosis progression in the arterial tree. Both phenomena can cause graft occlusion. Inhibition of growth factor release by arterial grafts can improve their clinical effectiveness

Consensus statement-graft treatment in cardiovascular bypass graft surgery

Coronary artery bypass grafting (CABG) is and continues to be the preferred revascularization strategy in patients with multivessel disease. Graft selection has been shown to influence the outcomes following CABG. During the last almost 60 years saphenous vein grafts (SVG) together with the internal mammary artery have become the standard of care for patients undergoing CABG surgery. While there is little doubt about the benefits, the patency rates are constantly under debate. Despite its acknowledged limitations in terms of long-term patency due to intimal hyperplasia, the saphenous vein is still the most often used graft. Although reendothelialization occurs early postoperatively, the process of intimal hyperplasia remains irreversible. This is due in part to the persistence of high shear forces, the chronic localized inflammatory response, and the partial dysfunctionality of the regenerated endothelium. "No-Touch" harvesting techniques, specific storage solutions, pressure controlled graft flushing and external stenting are important and established methods aiming to overcome the process of intimal hyperplasia at different time levels. Still despite the known evidence these methods are not standard everywhere. The use of arterial grafts is another strategy to address the inferior SVG patency rates and to perform CABG with total arterial revascularization. Composite grafting, pharmacological agents as well as latest minimal invasive techniques aim in the same direction. To give guide and set standards all graft related topics for CABG are presented in this expert opinion document on graft treatment

Mechanisms and prevention of intimal thickening of the autogenous vein grafts : possible involvement of nitric oxide

2003-05Platelet thrombosis, intimal hyperplasia, and the progression of atherosclerosis are the most important factors determining the patency of vein grafts for arterial occlusive disease. Interactions between aggregating platelets and the vessel wall play an important role in all of these processes. The endothelium modulates the underlying vascular smooth muscle by releasing nitric oxide (NO), a potent vasodilator and anti-aggregating substance. This review focuses on vascular modulation by NO in vein grafts.departmental bulletin pape

Chlamydia pneumoniae aggravates vein graft intimal hyperplasia in a rat model

<p>Abstract</p> <p>Background</p> <p>Along with angioplasty, autologus vein grafts are commonly used for artery bypass grafting in patients with advanced arterial stenosis and drug-resistant angina pectoris. Although initially a successful procedure, long-term functionality is limited due to proliferation and migration of smooth muscle cells. Like in atherosclerosis, common chronic infections caused by viruses and bacteria may contribute to this process of vein graft failure. Here we investigated the possible role of <it>Chlamydia pneumoniae </it>(<it>Cpn</it>) in the pathogenesis of venous graft failure in an experimental animal model. In 2 groups (n = 10 rats/group), an epigastric vein-to-common femoral artery interposition graft was placed. Immediately thereafter, rats were infected with <it>Cpn </it>(5*10⁸IFU) or injected with control solutions. Rats were sacrificed three weeks after surgery and the grafts were harvested for morphometrical and immunohistochemical analysis.</p> <p>Results</p> <p><it>Cpn </it>administration immediately after vein grafting resulted in a significant increase in medial cross-sectional area, wall thickness and total wall area. There were no significant differences in T-cell or macrophage influx. Likewise, although positive immunostaining for both HSP60 and CRP could be detected, no differences were found between groups. Based on the observation that the number of cells/μm²was also not altered, we conclude that Cpn infection stimulates smooth muscle cell proliferation by hereunto unknown molecular mechanisms, resulting in a significant increase in intimal hyperplasia.</p> <p>Conclusion</p> <p>In conclusion, in a well defined animal model we present here for the first time evidence for a role of <it>Chlamydia pneumoniae </it>in the process of venous graft failure.</p

Perivascular mast cells regulate vein graft neointimal formation and remodeling

Objective. Emerging evidence suggests an important role for mast cells in vein graft failure. This study addressed the hypothesis that perivascular mast cells regulate in situ vascular inflammatory and proliferative responses and subsequent vein graft neointimal lesion formation, using an optimized local mast cell reconstitution method. Methods and Results. Neointimal hyperplasia was induced by insertion of a vein graft into the right carotid artery in wild type and mast cell deficient KitW−sh/W−sh mice. In some experiments, mast cells were reconstituted systemically (tail vein injection of bone marrow-derived mast cells) or locally (directly into the right neck area) prior to vein grafting. Vein graft neointimal lesion formation was significantly (P &lt; 0.05) reduced in KitW−sh/W−sh mice. Mast cell deficiency reduced the number of proliferating cells, and inhibited L-selectin, CCL2, M-CSF and MIP-3α expression in the vein grafts. Local but not systemic mast cell reconstitution restored a perivascular mast cell population that subsequently promoted neointimal formation in mast cell deficient mice. Conclusion. Our data demonstrate that perivascular mast cells play a key role in promoting neointima formation by inducing local acute inflammatory and proliferative responses. These results suggest that ex vivo intraoperative targeting of mast cells may have therapeutic potential for the prevention of pathological vein graft remodeling

Pathobiology of saphenous vein grafts

The long saphenous vein graft is the commonest conduit used for coronary artery bypass surgery. The short and long term success of the procedure depends on the patency of these bypass grafts. Vein graft disease can be divided into early (in the fi rst 30 days), intermediate (1 month to 1 year) and late (over 1 year). Early graft failure is usually caused by graft thrombosis and may be related to the surgical procedure, intermediate graft disease results from intimal hyperplasia while late graft pathology is a consequence of atherosclerosis. The etiology and pathological processes leading to these damaging eff ects on saphenous vein grafts are tackled in this review. The loss of endothelial integrity, the phenotypic changes in vascular smooth muscle cells and involvement of adventitial cells with collaboration of blood borne factors lead to occlusive pathology of saphenous vein grafts. The accelerated intimal hyperplasia and atherosclerosis are characteristic pathobiological features of these vein grafts. Inflammatory and immunological changes and graft thrombosis are mediated through the secretion and up regulation of growth factors, pro coagulant substances and other proteins arising from the vein wall cells and the blood owing through them.peer-reviewe