Therapeutic myocardial angiogenesis: Past,present and future

One of the main goals in the treatment of myocardial ischemia is the development of effective therapy for angiogenesis and neovascularization. The first evidence demonstrating alleviation of myocardial ischemia and increased number of collateral blood vessels was reported in the early 90s following intra-coronary administration of basic fibroblast growth factor protein in canine. This study established the ground for extensive investigations to demonstrate the use of other angiogenic growth factor proteins, genes administered directly or incorporated in viruses, and more recently, endothelial progenitor stem cells (embryonic and adults). The positive results observed in animals failed, in most cases, to repeat themselves in clinical-trials in human patients. Therefore, additional experiments are warranted to allow full understanding of the mechanism underlying new blood vessel formation before further clinical studies are undertaken. This review will explore the milestones of angiogenic investigations and their clinical application.     

VEGF治疗心肌缺血的研究进展

血管内皮生长因子(VEGF)是一种促进血管生成的生长因子,因此被用于研究心肌缺血的治疗。目前,用VEGF重组蛋白和基因治疗心肌缺血的基础和临床试验都取得了相当的进展。对这方面的进展进行了综述。     

Therapeutic myocardial angiogenesis with vascular endothelial growth factors

Emerging evidence has shown that administration of angiogenic growth factors, either as recombinant protein or by gene transfer, can augment tissue perfusion through neovascularization in animal models of myocardial and hindlimb ischemia. Many cytokines have angiogenic activity; one of those that have been best studied in animal models and clinical trials is vascular endothelial growth factor (VEGF). VEGF has been known to be a key regulator of physiologic and pathologic angiogenesis associated with tumor. Recently the effect of VEGF is not restricted to the direct angiogenic effect in vivo but includes mobilization of bone-marrow-derived endothelial progenitor cells and augmentation of postnatal vasculogenesis in situ. Clinical trials of therapeutic angiogenesis with VEGF in patients with end-stage coronary artery disease have shown increases in exercise time and reductions in anginal symptoms and have provided objective evidence of improved perfusion and left ventricular function. Larger scale placebo-controlled trials with recombinant protein (rhVEGF₁₆₅) have been limited to intracoronary and intravenous administration and have shown favorable trends in exercise time and angina frequency. Small-scale, placebo-controlled, randomized clinical trials of gene transfer (phVEGF-2) via thoracotomy or percutaneous intramyocardial delivery demonstrated significant improvement of both subjective symptoms and objective measures of myocardial ischemia. Both therapeutic modalities appear to be safe and well tolerated. Further studies are required to determine the optimal dose, formulation, route of administration, and combinations of growth factors and the utility of adjunctive endothelial progenitor cell or other stem cell supplementation, to provide safe and effective therapeutic myocardial neovascularization. (Mol Cell Biochem 264: 63–74, 2004)     

Mesenchymal stem cells are superior to angiogenic growth factor genes for improving myocardial performance in the mouse model of acute myocardial infarction

Summary Both cell therapy and angiogenic growth factor gene therapy have been applied to animal studies and clinical trials. Little is known about the direct comparison between cell therapy and angiogenic growth factor gene therapy. The goal of this study was to compare the effects of human bone marrow-derived mesenchymal stem cells (hMSCs) transplantation and injection of angiogenic growth factor genes in a model of acute myocardial infarction in mice. The hMSCs were obtained from adult human bone marrow and expanded in vitro. The purity and characteristics of hMSCs were identified by flow cytometry and immunophenotyping. Immediately after ligation of the left anterior descending coronary artery in male severe combined immunodeficient (SCID) mice, culture-expanded hMSCs or angiogenic growth factor genes were injected intramuscularly at the left anterior free wall. The engrafted hMSCs were positive for cardiac marker, desmin. Infarct size was significantly smaller in the hMSCs-treated group than in the angiopoietin-1 (Ang-1) or vascular endothelial growth factor (VEGF)-treated group at day 28 after infarction. hMSCs transplantation was better in decreasing left ventricular end-diastolic dimension and increasing fractional shortening than Ang1 or VEGF gene therapy. Capillary density was markedly increased after hMSCs transplantation than Ang1 and VEGF gene therapy. In conclusion, intramyocardial transplantation of hMSCs improves cardiac function after acute myocardial infarction through enhancement of angiogenesis and myogenesis in the ischemic myocardium. hMSCs are superior to angiogenic growth factor genes for improving myocardial performance in the mouse model of acute myocardial infarction. Transplantation of MSCs may become the future therapy for acute myocardial infarction for myocardial regeneration.     

Gene therapy for chronic myocardial ischemia using platelet-derived endothelial cell growth factor in dogs

Platelet-derived endothelial cell growth factor (PD-ECGF), also known as thymidine phosphorylase (TP), has been reported to possess angiogenic activity and to inhibit apoptosis. This study was performed to determine whether PD-ECGF/TP can be used to ameliorate chronic myocardial ischemia. Myocardial ischemia was created in 40 mongrel dogs by placement of an ameroid constrictor on the proximal left anterior descending coronary artery (LAD). Plasmid vector encoding human PD-ECGF/TP cDNA (pCIhTP group; n = 12), empty vector pCI (pCI group; n = 12), or saline (Saline group; n = 12) was directly injected into the LAD territory 3 wk after ameroid constrictor implantation. Myocardial blood flow was detected using PET at baseline, 3 wk after ameroid constrictor implantation, and 2 wk after therapeutic treatment. At the end of the experiment, the hearts were isolated for biological and histological analysis. In the pCIhTP group, the transfected heart strongly expressed PD-ECGF/TP. The size of the infarct was smaller in the pCIhTP group than in the pCI or Saline group. The number of apoptotic myocardial cells was decreased in the pCIhTP group compared with the control groups based on triple immunohistochemical staining for von Willebrand factor, alpha-actin smooth muscle cells, and single-strand DNA. The level of proapoptotic protein Bax markedly decreased in the pCIhTP group compared with the other groups. Double immunohistochemical staining for von Willebrand factor and alpha-actin smooth muscle cells demonstrated that angiogenesis and arteriogenesis occurred, and paralleled the changes in myocardial blood flow and myocardial function in the pCIhTP group. We conclude that genetic approaches using PD-ECGF/TP to target the myocardium are effective for alleviating chronic myocardial ischemia.     

Myocardial angiogenesis

Coronary angiogenesis and collateral growth are chronic adaptations to myocardial ischemia, which are aimed at restoring coronary blood flow and salvaging myocardium in an ischemic region. Although we have assumed that myriad numbers of growth factors are involving in this adaptation, details in the underlying mechanisms, i.e., number of angiogenic factors, angiostatic factors, their receptors/signaling cascades, interactions/crosstalk among the signaling pathways and receptors, and the time course of expression/function of a particular factor or pathway during the successful adaptation are still unclear; they are, probably, harmonized like a symphony. Although there is as of yet no consensus about the mechanisms and causal factors for these cononary adaptations to ischemia, recent evidence strongly suggests that a balance between growth factors and growth inhibitors is critical. In this review we introduce vascular endothelial growth factor, angiopoietins, and angiostatin, as factors playing pivotal roles in coronary angiogenesis and collateral growth. (Mol Cell Biochem 264: 35–44, 2004)     

Angiogenic effects of dual gene transfer of bFGF and PDGF-BB after myocardial infarction

Therapeutic effects of combination of angiogenic growth factors for the treatment of ischemia after myocardial infarction are largely unknown. Plasmids expressing basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF-BB) or their combination with a 1:1 mass ratio were injected into hearts with 7-day-old myocardial infarction. Hearts were harvested after 1 and 4 weeks after gene transfer. The major findings in this chronic myocardial infarction model were that bFGF, PDGF-BB and their combination all had a more pronounced angiogenic effect on the arteriolar than the capillary level. bFGF stimulated both capillary and arteriolar growth while PDGF-BB preferentially stimulated arterioles. The combination increased the amount of both capillaries and arterioles and in addition gave rise to stable capillaries compared to single factor transfer but did not further enhance angiogenesis. No cardiovascular side effects were observed after gene transfer.     

Therapeutic myocardial angiogenesis with vascular endothelial growth factors

Emerging evidence has shown that administration of angiogenic growth factors, either as recombinant protein or by gene transfer, can augment tissue perfusion through neovascularization in animal models of myocardial and hindlimb ischemia. Many cytokines have angiogenic activity; one of those that have been best studied in animal models and clinical trials is vascular endothelial growth factor (VEGF). VEGF has been known to be a key regulator of physiologic and pathologic angiogenesis associated with tumor. Recently the effect of VEGF is not restricted to the direct angiogenic effect in vivo but includes mobilization of bone-marrow-derived endothelial progenitor cells and augmentation of postnatal vasculogenesis in situ. Clinical trials of therapeutic angiogenesis with VEGF in patients with end-stage coronary artery disease have shown increases in exercise time and reductions in anginal symptoms and have provided objective evidence of improved perfusion and left ventricular function. Larger scale placebo-controlled trials with recombinant protein (rhVEGF165) have been limited to intracoronary and intravenous administration and have shown favorable trends in exercise time and angina frequency. Small-scale, placebo-controlled, randomized clinical trials of gene transfer (phVEGF-2) via thoracotomy or percutaneous intramyocardial delivery demonstrated significant improvement of both subjective symptoms and objective measures of myocardial ischemia. Both therapeutic modalities appear to be safe and well tolerated. Further studies are required to determine the optimal dose, formulation, route of administration, and combinations of growth factors and the utility of adjunctive endothelial progenitor cell or other stem cell supplementation, to provide safe and effective therapeutic myocardial neovascularization.     

Myocardial angiogenesis

Coronary angiogenesis and collateral growth are chronic adaptations to myocardial ischemia, which are aimed at restoring coronary blood flow and salvaging myocardium in an ischemic region. Although we have assumed that myriad numbers of growth factors are involving in this adaptation, details in the underlying mechanisms, i.e., number of angiogenic factors, angiostatic factors, their receptors/signaling cascades, interactions/crosstalk among the signaling pathways and receptors, and the time course of expression/function of a particular factor or pathway during the successful adaptation are still unclear; they are, probably, harmonized like a symphony. Although there is as of yet no consensus about the mechanisms and causal factors for these cononary adaptations to ischemia, recent evidence strongly suggests that a balance between growth factors and growth inhibitors is critical. In this review we introduce vascular endothelial growth factor, angiopoietins, and angiostatin, as factors playing pivotal roles in coronary angiogenesis and collateral growth.     

New agents for the treatment of infarcted myocardium.

Local delivery of angiogenic growth factors for the treatment of myocardial ischemia has been well documented in various animal models, and clinical trials are now in progress. Our strategy was radically different, based on selective protection of some of the growth factors naturally present within the injured tissue. This protection was obtained by applying a chemically defined substitute for Dextran called RGTA11 (for ReGeneraTing Agent). RGTA is a family of agents, which has properties mimicking those of heparan sulfates toward heparin-binding growth factors (HBGF) and which stimulate tissue repair and protection. Indeed, we have previously shown that RGTA prevents most of the damage resulting from acute skeletal muscle ischemia [FASEB J. (1999) 13, 761-766]. We now show that the same agent can be used for the treatment of myocardial infarction. Acute myocardial infarction was induced in pigs by ligation of the left circumflex artery. One hour later, a single injection of 10 mg of RGTA11 was made in the center of the infarcted area. Three weeks later we observed 1) recovery of 84% of the initial left ventricular ejection fraction (only 55% in saline-treated controls), 2) an almost 50% reduction in the infarct size, 3) a reduction in fibrotic tissue formation, 4) significant preservation of myocytes, and 5) an increase in the number of blood vessels. The treatment of ischemic heart disease with RGTA would have clear advantages over other therapies such as growth factor, gene, or cell transplants, based on a stable, simple, and easy-to-develop chemical product.     

PlGF repairs myocardial ischemia through mechanisms of angiogenesis, cardioprotection and recruitment of myo-angiogenic competent marrow progenitors

Rationale

Despite preclinical success in regenerating and revascularizing the infarcted heart using angiogenic growth factors or bone marrow (BM) cells, recent clinical trials have revealed less benefit from these therapies than expected.

Objective

We explored the therapeutic potential of myocardial gene therapy of placental growth factor (PlGF), a VEGF-related angiogenic growth factor, with progenitor-mobilizing activity.

Methods and Results

Myocardial PlGF gene therapy improves cardiac performance after myocardial infarction, by inducing cardiac repair and reparative myoangiogenesis, via upregulation of paracrine anti-apoptotic and angiogenic factors. In addition, PlGF therapy stimulated Sca-1⁺/Lin⁻ (SL) BM progenitor proliferation, enhanced their mobilization into peripheral blood, and promoted their recruitment into the peri-infarct borders. Moreover, PlGF enhanced endothelial progenitor colony formation of BM-derived SL cells, and induced a phenotypic switch of BM-SL cells, recruited in the infarct, to the endothelial, smooth muscle and cardiomyocyte lineage.

Conclusions

Such pleiotropic effects of PlGF on cardiac repair and regeneration offer novel opportunities in the treatment of ischemic heart disease.     

Expression of VEGF and angiopoietins-1 and -2 during ischemia-induced coronary angiogenesis

The mechanisms underlying coronary capillary growth in response to ischemia are undefined. We hypothesized that the expression of vascular endothelial growth factor (VEGF) and angiopoietin (Ang)/Tie-2 were involved in capillary growth as an adaptation to ischemia. To test this hypothesis we measured capillary density, and the expressions of VEGF, Ang-1, Ang-2, and the Tie-2 receptor and its phosphorylation state during repetitive episodes of myocardial ischemia in chronically instrumented canines. Repetitive episodes of ischemia were induced by multiple (once/hour; 8/day), brief (2 min) occlusions of the left anterior descending coronary artery for 1, 7, 14, or 21 days. A sham group received the same instrumentation as the experimental groups but not the occlusion protocol. Collateral blood flow (microspheres) progressively increased from 9 +/- 3 to 83 +/- 10 ml. min-1. 100 g-1 on day 21. Capillary density increased at day 7 from 2378 +/- 53 (sham) to 2962 +/- 60/mm2, but it decreased to 2594 +/- 39/mm2 at day 21. Both VEGF and Ang-2 expression in myocardial interstitial fluid (Western analyses) peaked at day 3 of the repetitive occlusions but waned thereafter. In contrast the expression of Ang-1 remained relatively constant at all times in the occlusion groups. In shams, the expression of VEGF and Ang-2 was low and constant at all times. Tie-2 phosphorylation myocardial decreased decreased at day 7 but increased at 21 days of occlusions (P < 0.05). Our results indicate that capillary density was augmented by myocardial ischemia, but after development of collaterals and restoration of flow to the ischemic zone, capillary density returned to control levels. The change in capillary density paralleled with VEGF and Ang-2 expression but was inversely related to Tie-2 phosphorylation. We speculate the coronary angiogenesis is a coordinated event involving the expression of both VEGF and Ang-2 and that therapeutic angiogenic strategies may ultimately require treatment with more than a single factor.     

急性冠脉综合征患者外周血miR-378a-3p的表达及其诊断价值

摘要 目的：探讨急性冠脉综合征（ACS）患者外周血miR-378a-3p的表达及其诊断价值。方法：收集ACS患者和健康人（control）血清各3份,进行基因芯片检测筛选发现miR-378a-3p差异表达最为显著。利用网络药理学分析miR-378a-3p与心肌缺血的相关性。构建小鼠心肌缺血再灌注（IR）模型,按缺血再灌注时间不同分为假手术（sham）组、I/R 1h组、I/R 3h组、I/R 6h组、I/R 12h组,检测外周血miR-378a-3p表达水平以及心肌肌钙蛋白T（cTnT）浓度水平。收集ACS患者（101例）和同期健康体检人群（49例）,进行实时定量PCR,检测miR-378a-3p在ACS患者的表达。采用受试者工作特征曲线（ROC）分析miR-378a-3p诊断ACS的诊断效能,并对ACS进行风险评估。结果：基因芯片结果显示miR-378a-3p在ACS患者外周血中表达升高。网络药理学分析提示,miR-378a-3p与心肌缺血存在共同靶点且miR-378a-3p可能通过细胞凋亡和血管生成途径干预心肌缺血,有作为心肌缺血标志物的可能。动物实验证实miR-378a-3p表达量随心肌缺血时间变化逐渐上调且在6h时表达明显升高,且miR-378a-3p表达水平较cTnT更早在心肌缺血中出现高表达。临床数据分析表明,同健康对照组比较,ACS患者血清中的miR-378a-3p在发生ACS的临床症状后,在短时间内可以显著升高。miR-378a-3p作为ACS的特异性诊断指标时,曲线下面积（AUC）为0.8476（95%可信区间为0.7749- 0.9204, P<0.001）,约登指数为0.6981,采用0.214作为cut-off值,miR-378a-3p诊断ACS的灵敏度和特异度分别为86.14%和83.76%。进一步的研究显示,在缺血的转化过程中,根据疾病分类的不同,结果显示miR-378a-3p的表达趋势也不同,在不稳定型心绞痛（UA）和心肌梗死（MI）组中,miR-378a-3p都显著上调（P<0.001）,同MI患者相比,UA患者miR-378a-3p表达上调更显著（P<0.05）,提示在诊断和判断ACS的分类中有较好的价值。结论：ACS患者外周血中miR-378a-3p表达升高是ACS发生的独立危险因素,早期检测miR-378a-3p有助于预测ACS的发病情况。     

Programming Stem Cells for Therapeutic Angiogenesis Using Biodegradable Polymeric Nanoparticles

Controlled vascular growth is critical for successful tissue regeneration and wound healing, as well as for treating ischemic diseases such as stroke, heart attack or peripheral arterial diseases. Direct delivery of angiogenic growth factors has the potential to stimulate new blood vessel growth, but is often associated with limitations such as lack of targeting and short half-life in vivo. Gene therapy offers an alternative approach by delivering genes encoding angiogenic factors, but often requires using virus, and is limited by safety concerns. Here we describe a recently developed strategy for stimulating vascular growth by programming stem cells to overexpress angiogenic factors in situ using biodegradable polymeric nanoparticles. Specifically our strategy utilized stem cells as delivery vehicles by taking advantage of their ability to migrate toward ischemic tissues in vivo. Using the optimized polymeric vectors, adipose-derived stem cells were modified to overexpress an angiogenic gene encoding vascular endothelial growth factor (VEGF). We described the processes for polymer synthesis, nanoparticle formation, transfecting stem cells in vitro, as well as methods for validating the efficacy of VEGF-expressing stem cells for promoting angiogenesis in a murine hindlimb ischemia model.     

Therapeutic neovascularization for peripheral arterial diseases: advances and perspectives

Recently, with the better understanding of the mechanisms of neovascularization, many new therapeutic approaches to enhance neovascularization have emerged. Of these diverse emerging methods, use of growth factors and cells are the two major ones. This review will provide an update on the present understanding of the basic mechanisms of angiogenesis, vasculogenesis, and arteriogenesis, as a basis for designing future pro-neovascularization treatments. Several angiogenic factors including vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) have been implicated in augmenting the neovascularization process. However, single growth factors are not sufficient to generate functional vessels. In synergistic or complementary manner, these factors may be used in harmony to form long-term functional vessels. Cell therapy has the potential to supply stem/progenitor cells and multiple angiogenic factors to the region of ischemia. However, the efficacy of stem cells transplantation may be impaired by low survival rate, insufficient cell number and impaired function in aging and diseases. Combination of cells or cells primed with growth factor(s) or genetic modification may augment the therapeutic efficacy. This paper reviews critical literature in depth to elucidate the mechanism of therapeutic neovascularization, angiogenic factor therapy and cell transplantation. Based on past experience and actual knowledge, we propose future strategies for clinical application and discuss the problems and controversies that need to be addressed in order to fully exploit the potential of growth factors and/or cell transplantation with clinical relevance.     

Deregulation of XBP1 expression contributes to myocardial vascular endothelial growth factor‐A expression and angiogenesis during cardiac hypertrophy in vivo

Endoplasmic reticulum (ER) stress has been reported to be involved in many cardiovascular diseases such as atherosclerosis, diabetes, myocardial ischemia, and hypertension that ultimately result in heart failure. XBP1 is a key ER stress signal transducer and an important pro‐survival factor of the unfolded protein response (UPR) in mammalian cells. The aim of this study was to establish a role for XBP1 in the deregulation of pro‐angiogenic factor VEGF expression and potential regulatory mechanisms in hypertrophic and failing heart. Western blots showed that myocardial XBP1s protein was significantly increased in both isoproterenol (ISO)‐induced and pressure‐overload‐induced hypertrophic and failing heart compared to normal control. Furthermore, XBP1 silencing exacerbates ISO‐induced cardiac dysfunction along with a reduction of myocardial capillary density and cardiac expression of pro‐angiogenic factor VEGF‐A in vivo. Consistently, experiments in cultured cardiomyocytes H9c2 (2‐1) cells showed that UPR‐induced VEGF‐A upregulation was determined by XBP1 expression level. Importantly, VEGF‐A expression was increased in failing human heart tissue and blood samples and was correlated with the levels of XBP1. These results suggest that XBP1 regulates VEGF‐mediated cardiac angiogenesis, which contributes to the progression of adaptive hypertrophy, and might provide novel targets for prevention and treatment of heart failure.     

Forearm ischemia decreases endothelial colony-forming cell angiogenic potential

Background aimsCirculating endothelial progenitor cells and especially endothelial colony-forming cells (ECFCs) are promising candidate cells for endothelial regenerative medicine of ischemic diseases, but the conditions for an optimal collection from adult blood must be improved.MethodsOn the basis of a recently reported vascular niche of ECFCs, we hypothesized that a local ischemia could trigger ECFC mobilization from the vascular wall into peripheral blood to optimize their collection for autologous implantation in critical leg ischemia. Because the target population with critical leg ischemia is composed of elderly patients in whom a vascular impairment has been documented, we also analyzed the impact of aging on ECFC mobilization and vascular integrity.ResultsAfter having defined optimized ECFC culture conditions, we studied the effect of forearm ischemia on ECFC numbers and functions in 26 healthy volunteers (13 volunteers ages 20–30-years old versus 13 volunteers ages 60–70 years old). The results show that forearm ischemia induced an efficient local ischemia and a normal endothelial response but did not mobilize ECFCs regardless of the age group. Moreover, we report an alteration of angiogenic properties of ECFCs obtained after forearm ischemia, in vitro as well as in vivo in a hindlimb ischemia murine model. This impaired ECFC angiogenic potential was not associated with a quantitative modification of the circulating endothelial compartment.ConclusionsThe procedure of local ischemia, although reulting in a preserved endothelial reactivity, did not mobilize ECFCs but altered their angiogenic potential.     

Erratum to: Mechanistic insight of platelet apoptosis leading to non-surgical bleeding among heart failure patients supported by continuous-flow left ventricular assist devices

Cardiosphere-derived cells (CDCs) and bone marrow mesenchymal stem cells (MSCs) are popularly used in stem cell therapy for myocardial regeneration. The cell type that survives and maintains stem cell characteristics in the adverse microenvironment following ischemia–reperfusion injury is presumed to be ideal for transplantation. The study was therefore aimed at identifying the cell type with relatively greater resistance to ischemia–reperfusion injury. CDCs were isolated from the right atrial appendage and MSCs from bone marrow of patients who underwent coronary artery bypass graft surgery. Ischemia–reperfusion injury was simulated in vitro by subjecting the cells to hypoxia (0.5% O₂) followed by reintroduction of oxygen (HR injury). Greater resistance of CDCs to HR injury was apparent from the decreased expression of senescence markers and lower proportion of apoptotic cells (one-sixth of that in MSCs). HR injury retarded cell cycle progression in MSCs. Consequent to HR injury, cell migration and secretion of stromal-derived growth factor were stimulated, significantly in CDCs. The differentiation to myocyte lineage and angiogenesis assessed by tube formation ability was better for CDCs. Release of vascular endothelial growth factor was relatively more in CDCs and was further stimulated by HR injury. Differentiation to osteogenic and angiogenic lineage was stimulated by HR injury in MSCs. Compared to MSCs, CDCs appear to be the cell of choice for promoting myocardial regeneration by virtue of its survival capacity in the event of ischemic insult along with higher proliferation rate, migration efficiency, release of growth factors with paracrine effects and differentiation to cardiac lineage.     

Targeting tumor micro-environment for design and development of novel anti-angiogenic agents arresting tumor growth

Angiogenesis: a process of generation of new blood vessels has been proved to be necessary for sustained tumor growth and cancer progression. Inhibiting angiogenesis pathway has long been remained a significant hope for the development of novel, effective and target orientated antitumor agents arresting the tumor proliferation and metastasis. The process of neoangiogenesis as a biological process is regulated by several pro- and anti-angiogenic factors, especially vascular endothelial growth factor, fibroblast growth factor, epidermal growth factor, hypoxia inducible factor 1 and transforming growth factor. Every endothelial cell destined for vessel formation is equipped with receptors for these angiogenic peptides. Moreover, numerous other angiogenic cytokines such as platelet derived growth factor (PGDF), placenta growth factor (PGF), nerve growth factor (NGF), stem-cell factor (SCF), and interleukins-2, 4, 6 etc. These molecular players performs critical role in regulating the angiogenic switch. Couple of decade's research in molecular aspects of tumor biology has unraveled numerous structural and functional mysteries of these angiogenic peptides. In present article, a detailed update on the functional and structural peculiarities of the various angiogenic peptides is described focusing on structural opportunities made available that has potential to be used to modulate function of these angiogenic peptides in developing therapeutic agents targeting neoplastic angiogenesis. The data may be useful in the mainstream of developing novel anticancer agents targeting tumor angiogenesis. We also discuss major therapeutic agents that are currently used in angiogenesis associated therapies as well as those are subject of active research or are in clinical trials.     

Treatment of chronical myocardial ischemia by adenovirus-mediated hepatocyte growth factor gene transfer in minipigs

Growth factor gene transfer-induced therapeutic angiogenesis has become a novel approach for the treatment of myocardial ischemia. In order to provide a basis for the clinical application of an adeno- virus with hepatocyte growth factor gene (Ad-HGF) in the treatment of myocardial ischemia, we estab- lished a minipig model of chronically ischemic myocardium in which an Ameroid constrictor was placed around the left circumflex branch of the coronary artery (LCX). A total of 18 minipigs were ran- domly divided into 3 groups: a surgery control group, a model group and an Ad-HGF treatment group implanted with Ameroid constrictor. Ad-HGF or the control agent was injected directly into the ischemic myocardium, and an improvement in heart function and blood supply were evaluated. The results showed that myocardial perfusion remarkably improved in the Ad-HGF group compared with that in both the control and model groups. Four weeks after the treatment, the density of newly formed blood vessels was higher and the number of collateral blood vessels was greater in the Ad-HGF group than in the model group. The area of myocardial ischemia reduced evidently and the left ventricular ejection fraction improved significantly in the Ad-HGF group. These results suggest that HGF gene therapy may become a novel approach in the treatment of chronically ischemic myocardium.