Vascular Endothelial Growth Factor-165 Gene Therapy Promotes Cardiomyogenesis in Reperfused Myocardial Infarction

Do platelets protect the heart against ischemia/reperfusion injury or exacerbate cardiac ischemia/reperfusion injury? The role of PDGF, VEGF, and PAF

BACKGROUND

Acute myocardial infarction (AMI) is one of the main causes of death. It is quite obvious that there is an urgent need to develop new approaches for treatment of AMI.

OBJECTIVE

This review analyzes data on the role of platelets in the regulation of cardiac tolerance to ischemia/reperfusion (I/R).

METHODS

It was performed a search of topical articles using PubMed databases.

FINDINGS

Platelets activated by a cholesterol-enriched diet, thrombin, and myocardial ischemia exacerbate I/R injury of the heart. The P2Y12 receptor antagonists, remote ischemic postconditioning and conditioning alter the properties of platelets. Platelets acquire the ability to increase cardiac tolerance to I/R. Platelet-derived growth factors (PDGFs) increase tolerance of cardiomyocytes and endothelial cells to I/R. PDGF receptors (PDGFRs) were found in cardiomyocytes and endothelial cells. PDGFs decrease infarct size and partially abrogate adverse postinfarction remodeling. Protein kinase C, phosphoinositide 3-kinase, and Akt involved in the cytoprotective effect of PDGFs. Vascular endothelial growth factor increased cardiac tolerance to I/R and alleviated adverse postinfarction remodeling. The platelet-activating factor (PAF) receptor inhibitors increase cardiac tolerance to I/R in vivo. PAF enhances cardiac tolerance to I/R in vitro. It is possible that PAF receptor inhibitors could protect the heart by blocking PAF receptor localized outside the heart. PAF protects the heart through activation of PAF receptor localized in cardiomyocytes or endothelial cells. Reactive oxygen species and kinases are involved in the cardioprotective effect of PAF.

CONCLUSION

Platelets play an important role in the regulation of cardiac tolerance to I/R.

Lidocaine inhibits vascular endothelial growth factor-A-induced angiogenesis

PURPOSE

Angiogenesis is closely related to the pathophysiology of diseases such as cancer or ischemia. Here, we investigated the effect of lidocaine at clinically effective blood concentrations on vascular endothelial growth factor A (VEGF-A)-induced angiogenesis. In addition, we aimed to clarify the mechanisms by which lidocaine could inhibit angiogenesis.

METHODS

Angiogenesis was analyzed using commercially available in vitro assay kits in human umbilical vein endothelial cells (HUVECs)/normal human dermal fibroblast co-culture systems. The effects of lidocaine on cytotoxicity, VEGF-induced cell migration, and VEGF-induced cell proliferation were examined in HUVECs using lactate dehydrogenase cytotoxic, Boyden chamber, and WST-8 assays, respectively. The VEGF signaling pathway via VEGF receptor 2 (VEGFR-2) was analyzed by western blotting.

RESULTS

Lidocaine elicited a significant dose-dependent, angiogenesis-inhibitory effect at a concentration range of 1-10 μg/ml. At this concentration range, cell death was not observed. Lidocaine, at a concentration of 10 μg/ml, significantly inhibited cell proliferation but not cell migration, induced by VEGF-A in HUVECs. Furthermore, lidocaine, in a dose-dependent manner, significantly inhibited the VEGF-A-induced phosphorylation of VEGFR-2 at 3 and 10 μg/ml.

CONCLUSION

We demonstrated that lidocaine has an anti-angiogenesis effect on clinically effective blood concentrations without causing cell death. This finding could represent a new avenue for future research into anesthesia, cancer-related analgesia, and revascularization therapy.

Nanomedicine for Gene Delivery for the Treatment of Cardiovascular Diseases

Background:

Myocardial infarction (MI) is the most severe ischemic heart disease and di-rectly leads to heart failure till death. Target molecules have been identified in the event of MI including increasing angiogenesis, promoting cardiomyocyte survival, improving heart function and restraining inflammation and myocyte activation and subsequent fibrosis. All of which are substantial in cardiomy-ocyte protection and preservation of cardiac function.

Methodology:

To modulate target molecule expression, virus and non-virus-mediated gene transfer have been investigated. Despite successful in animal models of MI, virus-mediated gene transfer is hampered by poor targeting efficiency, low packaging capacity for large DNA sequences, immunogenicity induced by virus and random integration into the human genome.

Discussion:

Nanoparticles could be synthesized and equipped on purpose for large-scale production. They are relatively small in size and do not incorporate into the genome. They could carry DNA and drug within the same transfer. All of these properties make them an alternative strategy for gene transfer. In the review, we first introduce the pathological progression of MI. After concise discussion on the current status of virus-mediated gene therapy in treating MI, we overview the history and development of nanoparticle-based gene delivery system. We point out the limitations and future perspective in the field of nanoparticle vehicle.

Conclusion:

Ultimately, we hope that this review could help to better understand how far we are with nanoparticle-facilitated gene transfer strategy and what obstacles we need to solve for utilization of na-nomedicine in the treatment of MI.

Collagen-binding VEGF targeting the cardiac extracellular matrix promotes recovery in porcine chronic myocardial infarction

An effective therapy for chronic myocardial infarction (MI) has yet to be developed. Vascular endothelial growth factor (VEGF) promotes angiogenesis and improves cardiac function after MI. However, non-targeted delivery of VEGF decreases its therapeutic efficacy. In this study, for targeting the cardiac extracellular matrix, a collagen-binding domain (CBD) VEGF was used to bind specifically to the collagen-rich cardiac extracellular matrix. When intramyocardially injected into the peri-infarct region of a chronically infarcted porcine heart, CBD-VEGF attenuated the remodeling of the left ventricle with a decreased infarct size and promoted cardiomyocyte survival and angiogenesis 3 months after injection. In the 12-month trial, mature vessel networks and myocardium-like tissues were observed in the infarct region after CBD-VEGF injection. Also these beneficial effects might derive from CBD-VEGF significantly protecting cardiomyocytes from apoptosis and recruiting cardiac progenitor cells to the infarcted region. These results demonstrated that CBD-VEGF could be a promising therapeutic strategy for chronic MI.

Gene delivery of hypoxia-inducible VEGF targeting collagen effectively improves cardiac function after myocardial infarction

Vascular endothelial growth factor (VEGF) plays important roles in improvement of cardiac function following myocardial infarction (MI). However, the lack of a steerable delivery system of VEGF targeting the infarcted myocardium reduces the therapeutic efficacy and safety. Here, we constructed a series of lentiviral vector systems which could express a fusion protein consisted of a collagen-binding domain (CBD) and hVEGF (CBDhVEGF), under the control of 5HRE-hCMVmp (5HRE), the hypoxia-inducible promoter consists of five copies of the hypoxia-responsive element (HRE) and a human cytomegalovirus minimal promoter (hCMVmp). We demonstrated that 5HRE has the comparable ability to strongly drive CBDhVEGF under hypoxic condition as the ubiquitous CMV promoter, but it can hardly drive target gene under normoxic condition. 5HRE-drived CBDhVEGF specifically bound to type I collagen and significantly promoted the viability of HUVEC cells. Moreover, after injection of lentivirus into heart of mouse with MI, CBDhVEGF was mainly retained in infarcted myocardium where containing rich collagen and significantly improved angiogenesis and cardiac function when compared with hVEGF. Moreover, CBDhVEGF mediated by lentivirus has little leakage from infarcted zone into blood than hVEGF. Taken together, our results indicate that 5HRE-CBDhVEGF lentiviral vector system could improve cardiac function in the collagen-targeting and hypoxia-inducible manners.

Multiparametric CMR imaging of infarct remodeling in a percutaneous reperfused Yucatan mini-pig model

To further understanding of the temporal evolution and pathophysiology of adverse ventricular remodeling over the first 60 days following a myocardial infarction (MI) in both the infarcted and remote myocardium, we performed multi-parametric cardiac magnetic resonance (CMR) imaging in a closed-chest chronic Yucatan mini-pig model of reperfused MI. Ten animals underwent 90 min left anterior descending artery occlusion and reperfusion. Three animals served as controls. Multiparametric CMR (1.5T) was performed at baseline, Day 2, Day 30 and in four animals on Day 60 after MI. Left ventricular (LV) volumes and infarct size were measured. T₁ and T₂ mapping sequences were performed to measure values in the infarct and remote regions. Remote region collagen fractions were compared between infarcted animals and controls. Procedure success was 80%. The model created large infarcts (28 ± 5% of LV mass on Day 2), which led to significant adverse myocardial remodeling that stabilized beyond 30 days. Native T₁ values did not reliably differentiate remote and infarct regions acutely. There was no evidence of remote fibrosis as indicated by partition coefficient and collagen fraction analyses. The infarct T₂ values remained elevated up to 60 days after MI. Multiparametric CMR in this model showed significant adverse ventricular remodeling 30 days after MI similar to that seen in humans. In addition, this study demonstrated that remote fibrosis is absent and that infarct T₂ signal remains chronically elevated in this model. These findings need to be considered when designing preclinical trials using CMR endpoints.

Delivery of drugs, growth factors, genes and stem cells via intrapericardial, epicardial and intramyocardial routes for sustained local targeted therapy of myocardial disease

INTRODUCTION

Local myocardial delivery (LMD) of therapeutic agents is a promising strategy that aims to treat various myocardial pathologies. It is designed to deliver agents directly to the myocardium and minimize their extracardiac concentrations and side effects. LMD aims to enhance outcomes of existing therapies by broadening their therapeutic window and to utilize new agents that could not be otherwise be implemented systemically. Areas covered: This article provides a historical overview of six decades LMD evolution in terms of the approaches, including intrapericardial, epicardial, and intramyocardial delivery, and the wide array of classes of agents used to treat myocardial pathologies. We examines delivery of pharmaceutical compounds, targeted gene transfection and cell implantation techniques to produce therapeutic effects locally. We outline therapeutic indications, successes and failures as well as technical approaches for LMD. Expert opinion: While LMD is more complicated than conventional oral or intravenous administration, given recent advances in interventional cardiology, it is safe and may provide better therapeutic outcomes. LMD is complex as many factors impact pharmacokinetics and biologic result. The choice between routes of LMD is largely driven not only by the myocardial pathology but also by the nature and physicochemical properties of the therapeutic agents.

Modified VEGF targets the ischemic myocardium and promotes functional recovery after myocardial infarction

Vascular endothelial growth factor (VEGF) promotes angiogenesis and improves cardiac function after myocardial infarction (MI). However, the non-targeted delivery of VEGF decreases its therapeutic efficacy due to an insufficient local concentration in the ischemic myocardium. In this study, we used a specific peptide to modify VEGF and determined that this modified VEGF (IMT-VEGF) localized to the ischemic myocardium through intravenous injection by interacting with cardiac troponin I (cTnI). When IMT-VEGF was used to mediate cardiac repair in a rat model of ischemia-reperfusion (I-R) injury, we observed a decreased scar size, enhanced angiogenesis and improved cardiac function. Moreover, an alternative treatment using the repeated administration of a low-dose IMT-VEGF also promoted angiogenesis and functional recovery. The therapeutic effects of IMT-VEGF were further confirmed in a pig model of MI as the result of the conserved properties of its interacting protein, cTnI. These results suggest a promising therapeutic strategy for MI based on the targeted delivery of IMT-VEGF.

VEGF Splicing and the Role of VEGF Splice Variants: From Physiological-Pathological Conditions to Specific Pre-mRNA Splicing

During this past decade, the vascular endothelial growth factor (VEGF) pathway has been extensively studied. VEGF is a paradigm of molecular regulation since its expression is controlled at all possible steps including transcription, mRNA stability, translation, and pre-mRNA splicing. The latter form of molecular regulation is probably the least studied. This field has been neglected; yet different forms of VEGF with different sizes and different physiological properties issued from alternative splicing have been described a long time ago. Recently a new level of complexity was added to the field of splicing of VEGF pre-mRNA. Whereas thousands of publications have described VEGF as a pro-angiogenic factor, an alternative splicing event generates specific anti-angiogenic forms of VEGF that only differ from the others by a modification in the last six amino acids of the protein. According to the scientists who discovered these isoforms, which are indistinguishable from the pro-angiogenic ones with pan VEGF antibodies, some of the literature on VEGF is at least inexact if not completely false. Moreover, the presence of anti-angiogenic forms of VEGF may explain the disappointing efficacy of anti-VEGF therapies on the overall survival of patients with different forms of cancers and with wet age-related macular degeneration. This review focuses on the existence of the different alternative splice variants of VEGF and the molecular mechanisms associated with their expression and function.

Targeted delivery of human VEGF gene via complexes of magnetic nanoparticle-adenoviral vectors enhanced cardiac regeneration

This study assessed the concept of whether delivery of magnetic nanobeads (MNBs)/adenoviral vectors (Ad)–encoded hVEGF gene (Ad_hVEGF) could regenerate ischaemically damaged hearts in a rat acute myocardial infarction model under the control of an external magnetic field. Adenoviral vectors were conjugated to MNBs with the Sulfo-NHS-LC-Biotin linker. In vitro transduction efficacy of MNBs/Ad–encoded luciferase gene (Ad_luc) was compared with Ad_luc alone in human umbilical vein endothelial cells (HUVECs) under magnetic field stimulation. In vivo, in a rat acute myocardial infarction (AMI) model, MNBs/Ad_hVEGF complexes were injected intravenously and an epicardial magnet was employed to attract the circulating MNBs/Ad_hVEGF complexes. In vitro, compared with Ad_luc alone, MNBs/Ad_luc complexes had a 50-fold higher transduction efficiency under the magnetic field. In vivo, epicardial magnet effectively attracted MNBs/Ad_hVEGF complexes and resulted in strong therapeutic gene expression in the ischemic zone of the infarcted heart. When compared to other MI-treated groups, the MI-M⁺/Ad_hVEGF group significantly improved left ventricular function (p<0.05) assessed by pressure-volume loops after 4 weeks. Also the MI-M⁺/Ad_hVEGF group exhibited higher capillary and arteriole density and lower collagen deposition than other MI-treated groups (p<0.05). Magnetic targeting enhances transduction efficiency and improves heart function. This novel method to improve gene therapy outcomes in AMI treatment offers the potential into clinical applications.

Cardiac gene therapy in large animals: bridge from bench to bedside

Several clinical trials are evaluating gene transfer as a therapeutic approach to treat cardiac diseases. Although it has just started on the path to clinical application, recent advances in gene delivery technologies with increasing knowledge of underlying mechanisms raise great expectations for the cardiac gene therapy. Although in vivo experiments using small animals provide the therapeutic potential of gene transfer, there exist many fundamental differences between the small animal and the human hearts. Before applying the therapy to clinical patients, large animal studies are a prerequisite to validate the efficacy in an animal model more relevant to the human heart. Several key factors including vector type, injected dose, delivery method and targeted cardiac disease are all important factors that determine the therapeutic efficacy. Selecting the most optimal combination of these factors is essential for successful gene therapy. In addition to the efficacy, safety profiles need to be addressed as well. In this regard, large animal studies are best suited for comprehensive evaluation at the preclinical stages of therapeutic development to ensure safe and effective gene transfer. As the cardiac gene therapy expands its potential, large animal studies will become more important to bridge the bench side knowledge to the clinical arena.

Transmyocardial drilling revascularization combined with heparinized bFGF-incorporating stent activates resident cardiac stem cells via SDF-1/CXCR4 axis

OBJECTIVE

To investigate whether transmyocardial drilling revascularization combined with heparinized basic fibroblast growth factor (bFGF)-incorporating degradable stent implantation (TMDRSI) can promote myocardial regeneration after acute myocardial infarction (AMI).

METHODS

A model of AMI was generated by ligating the mid-third of left anterior descending artery (LAD) of miniswine. After 6 h, the animals were divided into none-treatment (control) group (n=6) and TMDRSI group (n=6). For TMDRSI group, two channels with 3.5 mm in diameter were established by a self-made drill in the AMI region, into which a stent was implanted. Expression of stromal cell-derived factor-1(α) (SDF-1(α)) and CXC chemokine receptor 4 (CXCR4), cardiac stem cell (CSC)-mediated myocardial regeneration, myocardial apoptosis, myocardial viability, and cardiac function were assessed at various time-points.

RESULTS

Six weeks after the operation, CSCs were found to have differentiated into cardiomyocytes to repair the infarcted myocardium, and all above indices showed much improvement in the TMDRSI group compared with the control group (P<0.001).

CONCLUSIONS

The new method has shown to be capable of promoting CSCs proliferation and differentiation into cardiomyocytes through activating the SDF-1/CXCR4 axis, while inhibiting myocardial apoptosis, thereby enhancing myocardial regeneration following AMI and improving cardiac function. This may provide a new strategy for myocardial regeneration following AMI.

Cardiovascular magnetic resonance imaging in delivering and evaluating the efficacy of hepatocyte growth factor gene in chronic infarct scar

BACKGROUND

In an open-chest model of acute infarct, epicardial delivery of hepatocyte growth factor (pCK-HGF-X7) gene improved left ventricle (LV) function. This study was designed to test (a) the efficacy of HGF gene in infarct scar delivered under magnetic resonance (MR) guidance and (b) the potential of multiple MR sequences in assessing the effects of pCK-HGF-X7 (treatment) and pCK-LacZ (control) genes on myocardial structure and function.

MATERIALS AND METHODS

Swine (six per group) were subjected to myocardial infarct, under X-ray fluoroscopy, and developed LV remodeling at 5 weeks. Multiple clinical magnetic resonance (MR) imaging sequences were performed before delivery of gene (at 5 weeks after infarction) and 5 weeks after delivery of gene. Under MR guidance, the active endovascular catheter was introduced into LV to transendocardially deliver 3.96 × 10(11) viral copies of pCK-HGF-X7 or pCK-LacZ in the border and core of the infarct scar. Histological evaluation of the infarct scar was performed 5 weeks after delivery of gene.

RESULTS

At 5 weeks after infarction, there was no significant difference in measured cardiovascular MR parameters between the groups. The pCK-HGF-X7 gene caused significant improvement in the following parameters (P<.05 for these parameters): three-dimensional (3D) strain (radial, circumferential, and longitudinal) and perfusion (maximum upslope, peak signal intensity, and time to peak) compared with control pCK-LacZ at 5 weeks after delivery of the genes. The ejection fraction was higher in pCK-HGF-X7-treated (43 ± 1%) than in pCK-LacZ control (37 ± 1%, P<.05) animals. These changes are associated with a decrease in infarct scar size (11.3 ± 2.0% in pCK-LacZ control and 6.7 ± 1.3% in pCK-HGF-X7-treated animals, P<.01) and infarct transmurality in four out of five infarct scar segments (P<.05) on delayed contrast-enhanced MR imaging. Microscopic study confirmed the increase in capillary (P<.05) and arteriole (P<.05) density of infarct scar in pCK-HGF-X7-treated animals compared with pCK-LacZ control animals.

CONCLUSIONS

Hepatocyte growth factor gene (pCK-HGF-X7) delivered under MR guidance into infarct scar ameliorated global function and 3D strain, increased regional perfusion and infarct resorption, and enhanced angiogenesis/arteriogenesis. This feasibility study provides novel approach and analysis methods and instrumentation for delivering and evaluating new locally delivered therapies.