Novel vectors forin vivogene delivery to vascular tissue

The Function and Therapeutic Potential of Long Non-coding RNAs in Cardiovascular Development and Disease

The popularization of genome-wide analyses and RNA sequencing led to the discovery that a large part of the human genome, while effectively transcribed, does not encode proteins. Long non-coding RNAs have emerged as critical regulators of gene expression in both normal and disease states. Studies of long non-coding RNAs expressed in the heart, in combination with gene association studies, revealed that these molecules are regulated during cardiovascular development and disease. Some long non-coding RNAs have been functionally implicated in cardiac pathophysiology and constitute potential therapeutic targets. Here, we review the current knowledge of the function of long non-coding RNAs in the cardiovascular system, with an emphasis on cardiovascular development and biology, focusing on hypertension, coronary artery disease, myocardial infarction, ischemia, and heart failure. We discuss potential therapeutic implications and the challenges of long non-coding RNA research, with directions for future research and translational focus.

Efficient transduction of vascular smooth muscle cells with a translational AAV2.5 vector: a new perspective for in-stent restenosis gene therapy

Coronary artery disease represents the leading cause of mortality in the developed world. Percutaneous coronary intervention (PCI) involving stent placement remains disadvantaged by restenosis or thrombosis. Vascular gene-therapy-based methods may be approached, but lack a vascular gene delivery vector.

We report a safe and efficient long-term transduction of rat carotid vessels after balloon-injury intervention with a translational optimized AAV2.5 vector. Compared to other known AAV serotypes, AAV2.5 demonstrated the highest transduction efficiency of human coronary artery vascular smooth muscle cells (VSMC) in vitro. Local delivery of AAV2.5-driven transgenes in injured carotid arteries resulted in transduction as soon as day 2 after surgery and persisted for at least 30 days. In contrast to adenovirus 5 vector, inflammation was not detected in AAV2.5-transduced vessels. The functional effects of AAV2.5-mediated gene transfer on neointimal thickening were assessed using the sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA2a) human gene, known to inhibit VSMC proliferation. At 30 days, human SERCA2a mRNA was detected in transduced arteries. Morphometric analysis revealed a significant decrease of neointimal hyperplasia in AAV2.5-SERCA2a transduced arteries: 28.36±11.30 (n=8) vs 77.96±24.60 (n=10) μm², in AAV2.5-GFP-infected, p<0.05.

In conclusion, AAV2.5 vector can be considered as a promising safe and effective vector for vascular gene therapy.

Integrase-deficient lentiviral vectors mediate efficient gene transfer to human vascular smooth muscle cells with minimal genotoxic risk

We have previously shown that injury-induced neointima formation was rescued by adenoviral-Nogo-B gene delivery. Integrase-competent lentiviral vectors (ICLV) are efficient at gene delivery to vascular cells but present a risk of insertional mutagenesis. Conversely, integrase-deficient lentiviral vectors (IDLV) offer additional benefits through reduced mutagenesis risk, but this has not been evaluated in the context of vascular gene transfer. Here, we have investigated the performance and genetic safety of both counterparts in primary human vascular smooth muscle cells (VSMC) and compared gene transfer efficiency and assessed the genotoxic potential of ICLVs and IDLVs based on their integration frequency and insertional profile in the human genome. Expression of enhanced green fluorescent protein (eGFP) mediated by IDLVs (IDLV-eGFP) demonstrated efficient transgene expression in VSMCs. IDLV gene transfer of Nogo-B mediated efficient overexpression of Nogo-B in VSMCs, leading to phenotypic effects on VSMC migration and proliferation, similar to its ICLV version and unlike its eGFP control and uninfected VSMCs. Large-scale integration site analyses in VSMCs indicated that IDLV-mediated gene transfer gave rise to a very low frequency of genomic integration compared to ICLVs, revealing a close-to-random genomic distribution in VSMCs. This study demonstrates for the first time the potential of IDLVs for safe and efficient vascular gene transfer.

Vascular smooth-muscle-cell activation: proteomics point of view

Vascular smooth-muscle cells (VSMCs) are the main component of the artery medial layer. Thanks to their great plasticity, when stimulated by external inputs, VSMCs react by changing morphology and functions and activating new signaling pathways while switching others off. In this way, they are able to increase the cell proliferation, migration, and synthetic capacity significantly in response to vascular injury assuming a more dedifferentiated state. In different states of differentiation, VSMCs are characterized by various repertories of activated pathways and differentially expressed proteins. In this context, great interest is addressed to proteomics technology, in particular to differential proteomics. In recent years, many authors have investigated proteomics in order to identify the molecular factors putatively involved in VSMC phenotypic modulation, focusing on metabolic networks linking the differentially expressed proteins. Some of the identified proteins may be markers of pathology and become useful tools of diagnosis. These proteins could also represent appropriately validated targets and be useful either for prevention, if related to early events of atherosclerosis, or for treatment, if specific of the acute, mid, and late phases of the pathology. RNA-dependent gene silencing, obtained against the putative targets with high selective and specific molecular tools, might be able to reverse a pathological drift and be suitable candidates for innovative therapeutic approaches.

Development of viral vectors for use in cardiovascular gene therapy

Cardiovascular disease represents the most common cause of mortality in the developed world but, despite two decades of promising pre-clinical research and numerous clinical trials, cardiovascular gene transfer has so far failed to demonstrate convincing benefits in the clinical setting. In this review we discuss the various targets which may be suitable for cardiovascular gene therapy and the viral vectors which have to date shown the most potential for clinical use. We conclude with a summary of the current state of clinical cardiovascular gene therapy and the key trials which are ongoing.

Local lentiviral short hairpin RNA silencing of CCR2 inhibits vein graft thickening in hypercholesterolemic apolipoprotein E3-Leiden mice

OBJECTIVE

Inflammatory responses to vascular injury are key events in vein graft disease and accelerated atherosclerosis, which may result in bypass failure. The monocyte chemoattractant protein-1 (MCP-1)/CC-chemokine receptor (CCR)-2 pathway is hypothesized to play a central role. A murine model for vein graft disease was used to study the effect of local application of lentiviral short hairpin RNA (shRNA) targeted against CCR2.

METHODS

A venous interposition was placed into the carotid artery of hypercholesterolemic apolipoprotein E3-Leiden (APOE*3-Leiden) mice to induce vein graft thickening with features of accelerated atherosclerosis. To demonstrate the efficacy of the lentiviral shRNA targeting murine CCR2 (shCCR2) in blocking vein graft disease in vivo, lentiviral shCCR2 or a control lentivirus was used to infect the vein graft locally (n = 8).

RESULTS

Vascular CCR2 and MCP-1 messenger RNA expression levels were significantly upregulated during lesion progression in the vein graft. Infection of smooth muscle cells (SMCs) with a lentiviral shRNA targeting shCCR2 completely abolished MCP-1-induced SMC migration and inhibited SMC proliferation in vitro (n = 3 per group). Morphometric analysis of sections of grafts showed a significant 38% reduction in vein graft thickening in the shCCR2-treated mice 4 weeks after surgery (control, 0.42 +/- 0.05 mm(2); shCCR2, 0.26 +/- 0.03 mm(2); P = .007).

CONCLUSION

Vascular CCR2 contributes to vein graft disease, and local application of shRNA against CCR2 to the vessel wall prevents vein graft thickening in hypercholesterolemic mice, suggesting that local overexpressing of shRNA using organ-targeted lentiviral gene delivery may be a promising therapeutic tool to improve vein graft disease in bypassed patients.

CLINICAL RELEVANCE

Vein graft disease is an important clinical issue that results from an inflammatory response. The monocyte chemoattractant protein (MCP)-1/CC-chemokine receptor (CCR)-2 pathway plays a key role in the initiation and development of vein graft disease. This study demonstrates that perivascular overexpression of short hairpin RNA, targeted against CCR2, inhibits vein graft thickening. These data show that organ-targeted gene therapy against CCR2 in the vessel wall could be a promising therapeutic tool to improve vein graft patency in bypassed patients.

Adenovirus-Mediated VEGF Gene Therapy Enhances Venous Thrombus Recanalization and Resolution

Objective— Rapid thrombus recanalization reduces the incidence of post–thrombotic complications. This study aimed to discover whether adenovirus-mediated transfection of the vascular endothelial growth factor gene (ad.VEGF) enhanced thrombus recanalization and resolution.

Methods and Results— In rats, thrombi were directly injected with either ad.VEGF (n=40) or ad.GFP (n=37). Thrombi in SCID mice (n=12) were injected with human macrophages transfected with ad.VEGF or ad.GFP. Thrombi were analyzed at 1 to 14 days. GFP was found mainly in the vein wall and adventitia by 3 days, but was predominantly found in cells within the body of thrombus by day 7. VEGF levels peaked at 4 days (376±299 pg/mg protein). Ad.VEGF treatment reduced thrombus size by >50% (47.7±5.1 mm 2 to 22.0±4.0 mm 2 , P =0.0003) and increased recanalization by >3-fold (3.9±0.69% to 13.6±4.1%, P =0.024) compared with controls. Ad.VEGF treatment increased macrophage recruitment into the thrombus by more than 50% ( P =0.002). Ad.VEGF-transfected macrophages reduced thrombus size by 30% compared with controls (12.3±0.89 mm 2 to 8.7±1.4 mm 2 , P =0.04) and enhanced vein lumen recanalization (3.39±0.34% to 5.07±0.57%, P =0.02).

Conclusion— Treatment with ad.VEGF enhanced thrombus recanalization and resolution, probably as a consequence of an increase in macrophage recruitment.