转录调节因子ETS-1在血管生成中的作用

学术背景：ETS—1是ETS家族转录因子的第一个亚族，在血管生成中起重要的调控作用。近年研究显示ETS—1对血管内皮细胞的凋亡也有重要的调控作用，在血管生成开始，ETS—1决定局部内皮细胞的凋亡。 目的：总结血管生长因子ETS-1在血管生成及细胞凋亡中的作用和研究进展。检索策略：由该论文的研究人员应用计算机检索PubMed，Sciencedirect，Ovid数据库1990—01／2007—09的相关文献，检索词为“ETS—1，angiogenesis，apoptosis，osteoblast，osteoclast”，限定文章语言种类为English。同时计算机检索中国期刊全文数据库、万方数据库2000—01／2007—06期间的相关文章，检索词为“ETS-1，血管生成，细胞凋亡，内皮细胞”，限定文章语言种类为中文。共检索到128篇文献，对资料进行初审，纳入标准：①与ETS—l在血管生成和细胞凋亡密切相关。②同一领域选择近期发表或在权威杂志上发表的文章。排除标准：重复性研究。 文献评价：文献的来源主要是EST-1在血管生成和细胞凋亡方面的试验研究。所选用的31篇文献中，2篇为综述，29为临床或基础实验研究。 资料综合：①正畸牙齿移动中，牙槽骨的改建是骨吸收和新骨形成的动态平衡过程。这一过程机制复杂，受多种因子的调节。②在众多正调控因子中ETS—1是主要的促血管形成因子，在血管形成中起重要作用。③研究表明，4种典型的血管生长因子：酸性成纤维细胞生长因子，碱性成纤维细胞生长因子，血管内皮生长因子和表皮生长因子能够诱导血管内皮细胞的ETS—1的表达，ETS—1通过诱导血管生成的相关因子如基质金属蛋白酶和整合素B3的表达促进血管生成。④关于ETS-1在调控血管生成方面取得很大的进展，但仍存在许多问题，如ETS—1如何精确的调控血管生成，如何精确的调节细胞凋亡的基因表达?     

The WNT antagonist Dickkopf2 promotes angiogenesis in rodent and human endothelial cells

Neovessel formation is a complex process governed by the orchestrated action of multiple factors that regulate EC specification and dynamics within a growing vascular tree. These factors have been widely exploited to develop therapies for angiogenesis-related diseases such as diabetic retinopathy and tumor growth and metastasis. WNT signaling has been implicated in the regulation and development of the vascular system, but the detailed mechanism of this process remains unclear. Here, we report that Dickkopf1 (DKK1) and Dickkopf2 (DKK2), originally known as WNT antagonists, play opposite functional roles in regulating angiogenesis. DKK2 induced during EC morphogenesis promoted angiogenesis in cultured human endothelial cells and in in vivo assays using mice. Its structural homolog, DKK1, suppressed angiogenesis and was repressed upon induction of morphogenesis. Importantly, local injection of DKK2 protein significantly improved tissue repair, with enhanced neovascularization in animal models of both hind limb ischemia and myocardial infarction. We further showed that DKK2 stimulated filopodial dynamics and angiogenic sprouting of ECs via a signaling cascade involving LRP6-mediated APC/Asef2/Cdc42 activation. Thus, our findings demonstrate the distinct functions of DKK1 and DKK2 in controlling angiogenesis and suggest that DKK2 may be a viable therapeutic target in the treatment of ischemic vascular diseases.     

A growth factor mixture that significantly enhances angiogenesis in vivo

Studies of therapeutic angiogenesis have generally focused on single growth factor strategies. However, multiple factors participate in angiogenesis. We evaluated the angiogenic potential of a growth factor mixture (GFm) derived from bovine bone. The major components of GFm (SDS-polyacrylamide gel electrophoresis, mass spectrometry, and Western blot) include transforming growth factor-beta1-3, bone morphogenic protein-2-7, and fibroblast growth factor-1. GFm was first shown to induce an angiogenic response in chorioallantoic membranes. Next, myocardial ischemia was induced in 21 dogs (ameroid) that were randomized 3 weeks later to received GFm 1 mg/ml (I), GFm 10 mg/ml (II), or placebo (P) (with investigators blinded to conditions) injected in and adjacent to ischemic myocardium. Dogs were assessed 6 weeks later using quantitative and semiquantitative measures. There were GFm concentration-dependent improvements in distal left anterior descending artery (LAD) opacification by angiography (P: 0.4 +/- 0.2, I: 1.1 +/- 0.14, II: 1.6 +/- 0.3, angiographic score p = 0.014). Histologically, there was also concentration-dependent vascular growth response of relatively large vessels (P: 0.21 +/- 0.15, I: 1.00 +/- 0.22, II: 1.71 +/- 0.18, vascular growth score p = 0.001). Resting myocardial blood flow (colored microspheres) was not significantly impaired in any group. However, maximum blood flow (adenosine) was reduced in ischemic territories and did not improve in GFm-treated hearts. GFm, a multiple growth factor mixture, is a potent angiogenic agent that stimulates large vessel growth. Although blood flow did not improve during maximal vasodilatory stress, large intramyocardial collateral vessels developed and angiographic visualization of the occluded distal LAD improved significantly. The use of multiple growth factors may be an effective strategy for therapeutic angiogenesis provided a more effective delivery strategy is devised that can achieve improved maximum blood flow potential.     

Contribution of VEGF and PEDF to choroidal angiogenesis: a need for balanced expressions

Ocular angiogenesis may lead to visual impairment and even irreversible blindness in people of all ages worldwide. Choroidal neovascularization (CNV), a major clinical complication of ocular angiogenesis, is an important cause of vision loss that affects a large number of people. Physiological angiogenesis is tightly controlled by a balance in the expression of angiogenic and anti-angiogenic factors. While the underlying mechanism of CNV is complex, it is attributed to an upset in this balance. The vascular endothelial growth factor (VEGF) is essential in the development of CNV as one of the most potent angiogenic stimulators and vascular permeability factors. Pigment epithelium derived factor (PEDF) is a strong inhibitor of angiogenesis with high neuroprotective effects. VEGF and PEDF both possess multiple biological activities and functions that affect a large variety of tissue cells of the eye and other organs. Inappropriate expression levels are associated with many diseases involving neovascularization. This paper describes the unbalanced expressions of VEGF and PEDF as a cause of CNV. Based on the respective angiogenic and anti-angiogenic properties of VEGF and PEDF, experimental models have been devised to genetically reduce VEGF or enhance PEDF to achieve therapeutic effects. Gene therapy for CNV is promising and is under intensive research.     

A hydrophobic gelatin fiber sheet promotes secretion of endogenous vascular endothelial growth factor and stimulates angiogenesis

In tissue engineering and regenerative medicine, the formation of vascular beds is an effective method to supply oxygen and nutrients to implanted cells or tissues to improve their survival and promote normal cellular functions. Various types of angiogenic materials have been developed by incorporating growth factors, such as vascular endothelial growth factor, in biocompatible materials. However, these exogenous growth factors suffer from instability and inactivation under physiological conditions. In this study, we designed a novel angiogenic electrospun fiber sheet (C16-FS) composed of Alaska pollock-derived gelatin (ApGltn) modified with hexadecyl (C16) groups to induce localized and sustained angiogenesis without growth factors. C16-FS was thermally crosslinked to enhance its stability. We demonstrated that C16-FS swells in phosphate-buffered saline for over 24 h and resists degradation. Laser doppler perfusion imaging showed that C16-FS induced increased blood perfusion when implanted subcutaneously in rats compared with unmodified ApGltn-fiber sheets (Org-FS) and the sham control. Furthermore, angiogenesis was sustained for up to 7 days following implantation. Immunohistochemical studies revealed elevated nuclear factor-κB and CD31 levels around the C16-FS implantation site compared with the Org-FS implantation site and the control incision site. These results demonstrate that C16-FS is a promising angiogenic material to promote the formation of vascular beds for cell and tissue transplantation without the need for growth factors.

In vivo long-term growth factor-free angiogenesis by LPS-mimicking C16-modified gelatin based electrospun fiber sheet.     

Gene therapy for therapeutic angiogenesis in critically ischaemic lower limb - on the way to the clinic

Currently, no effective pharmacological treatment is available for vascularisation defects in lower limbs. Many patients presenting with persistent pain and ischaemic ulcers are not suitable candidates for surgical or endovascular approaches. Further refinement of the available methods will undoubtedly lead to a more active approach towards treatment of peripheral arterial occlusive disease (PAOD). Recently, therapeutic angiogenesis, in the form of recombinant growth factor administration or gene therapy, has emerged as a novel tool to treat these patients. However, improved gene transfer methods and better understanding of blood vessel formation are required to bring therapeutic angiogenesis to clinical practice. Here we review the clinical problem (PAOD), mechanisms of blood vessel formation (angiogenesis, vasculogenesis and arteriogenesis), experimental evidence and clinical trials for therapeutic angiogenesis in critically ischaemic lower limbs. Also, angiogenic growth factors, including vascular endothelial growth factors (VEGFs) and fibroblast growth factors (FGFs), delivery methods, and vectors for gene transfer in skeletal muscle, are discussed. In addition to vascular growth, gene transfer of growth factors may enhance regeneration, survival, and innervation of ischaemic skeletal muscle. Nitric oxide (NO) appears to be a key mediator in vascular homeostasis and growth, and a reduction in its production by age, hypercholesterolemia or diabetes leads to the impairment of ischaemic disorders.     

Vascular endothelial growth factors in retinal and choroidal neovascular diseases

Abstract

Angiogenesis, or neovascularization, refers to development of new vessels from pre-existing vasculature. Retinal and choroidal neovascularization leads to oedema, haemorrhages, and fibrosis, causing visual impairment and blindness. In multiple studies, vascular endothelial growth factor (VEGF) has been shown to be the most important factor in ocular angiogenesis. Recently discovered anti-VEGF treatments have revolutionized the therapy of neovascular diseases in the eye. These agents have been shown not just to stop the angiogenic process and maintain visual acuity but also improve vision in a great proportion of patients at least during a 2-year follow-up. However, there are also problems with these agents and their delivery regimens, and new therapeutic strategies are needed. This review summarizes the most important growth factors participating in the angiogenic process in the retina and the choroid, diseases where angiogenesis plays the most devastating part causing visual impairment, as well as current antiangiogenic treatments for these diseases.     

Vascular endothelial growth factors in retinal and choroidal neovascular diseases

Angiogenesis, or neovascularization, refers to development of new vessels from pre-existing vasculature. Retinal and choroidal neovascularization leads to oedema, haemorrhages, and fibrosis, causing visual impairment and blindness. In multiple studies, vascular endothelial growth factor (VEGF) has been shown to be the most important factor in ocular angiogenesis. Recently discovered anti-VEGF treatments have revolutionized the therapy of neovascular diseases in the eye. These agents have been shown not just to stop the angiogenic process and maintain visual acuity but also improve vision in a great proportion of patients at least during a 2-year follow-up. However, there are also problems with these agents and their delivery regimens, and new therapeutic strategies are needed. This review summarizes the most important growth factors participating in the angiogenic process in the retina and the choroid, diseases where angiogenesis plays the most devastating part causing visual impairment, as well as current antiangiogenic treatments for these diseases.     

Anti-angiogenic therapy in breast cancer

Breast cancer is a worldwide epidemic among women, and one of the most rapidly increasing cancers. Not only the incidence rate but also the death rate is increasing. Despite enthusiastic efforts in early diagnosis, aggressive surgical treatment and application of additional non-operative modalities, its prognosis is still dismal. This emphasizes the necessity to develop new measures and strategies for its prevention. The understanding of the biology of angiogenesis is improving rapidly, offering the hope for more specific vascular targeting of tumor neovasculature. Anti-angiogenic therapy is a promising, relatively new form of cancer treatment using drugs called angiogenesis inhibitors that specifically inhibit new blood vessel growth. Extensive studies conducted over the past few years have recognized that overexpression of COX-2, VEGF in the cancer might be the leading factors, can induce angiogenesis via induction of multiple pro-angiogenic regulators. Breast tumor growth and metastasization are both hormone-sensitive and angiogenesis-dependent. A single angiogenic inhibitor is not capable to inhibit angiogenesis. Therefore, we should select a combination of angiogenesis inhibitors targeting COX-2, VEGF, and bFGF pathway. This article reviews the background and implementation of the current use of angiogenesis inhibitors and discusses the likely therapeutic roles in the early and advanced breast cancer together with its potential for chemoprevention.     

Recent developments in the cell biology of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor: activities on endothelial cells

Summary Granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor were considered as growth and differentiation factors restricted to hematopoietic cells. It was recently found that non-hematopoietic cells, including endothelial cells, respond to these cytokines. In this review we describe their effects on endothelial cells, underlining their role in the behavior and survival of the microenvironment of bone marrow, in the angiogenesis process related to the progression of solid tumors and of vascular tumors, and in the homing of lymphocytes.     

Embryonic angiogenesis factors.

The vascular system develops during embryonic development by at least two distinct processes; vasculogenesis is the development of blood vessels from in situ differentiating angioblasts and angiogenesis is the sprouting of capillaries from pre-existing vessels. The molecular mechanisms involved in the regulation of these processes are poorly understood. Endoderm-mesoderm interactions seem to play an important role in angioblast differentiation and vasculogenesis. Soluble angiogenic factors may be involved in the vascularization of some embryonic organs, e.g. kidney and brain. Angiogenic growth factors have been isolated and purified from embryonic brain and identified as acidic and basic fibroblast growth factors. More specific endothelial cell growth factors such as platelet-derived endothelial cell growth factor and vascular endothelial growth factor may also play a role in embryonic angiogenesis.     

骨髓液促进鸡胚绒毛尿囊膜血管的生成

背景:生长因子能促进侧支血管的发育,且多种因子协同效果更为明显,骨髓液中富含多种生长因子.目的:观察血管内膜损伤后的骨髓液对鸡胚绒毛尿囊膜血管生成的作用.方法:受精蛋70枚在(37.5±0.5) ℃条件下孵育,第7天开窗,第8天将存活鸡胚随机分为生理盐水组、正常血清组、正常骨髓液组、损伤血清组、损伤骨髓液组以及血管内皮生成因子组,每组10枚,分别滴加5 μL兔正常血清、5 μL兔骨髓液、5 μL兔血管内膜损害血清、5 μL兔血管内膜损害骨髓液、5 μL生理盐水及0.3 μg 血管内皮生长因子进鸡胚绒毛尿囊膜中,连续3 d.数码相机拍照后平铺于载玻片上,计数鸡胚绒毛尿囊膜新生的血管数目.结果与结论:与正常血清组相比,正常骨髓液组、血管内膜损害血清组鸡胚绒毛尿囊膜新生的血管总数明显增多,大中血管明显增生;且血管内膜损害血清组大、中血管数更为明显增加.提示正常骨髓液具有明显的促进鸡胚绒毛尿囊膜模型血管生成的作用,其强度优于血管内皮生长因子;血管内膜损伤第7天的血清和骨髓液能够明显的促进鸡胚绒毛尿囊膜上的血管生成,其强度优于血管内皮生长因子组.     

Gene therapy for peripheral arterial diseases

Therapeutic angiogenesis using angiogenic growth factor is expected to be a new treatment for with patients with critical limb ischemia. The first human clinical trial treating peripheral vascular disease was started in 1994 using vascular endothelial growth factor (VEGF). To date, other potent angiogenic growth factors, such as fibroblast growth factor(FGF) or hepatocyte growth factor(HGF), have been also estimated in clinical trials for peripheral arterial disease. Several results from phase 1 or 2 trials using VEGF, FGF and HGF gene were encouraging. Phase 3 trials are now ongoing and their results are expected.