Therapeutic angiogenesis for ischemic diseases

The clinical consequences of peripheral arterial disease include pain on walking, pain at rest and loss of tissue integrity in the distal ischemic limbs. Although development of beneficial drugs and intervention devices do contribute to the treatment of this disease, critical limb ischemia is estimated to develop in 500 to 1,000 individuals per million per year. As angiogenic growth factors can stimulate the development of collateral arteries, a concept called "therapeutic angiogenesis" is now evaluated in the clinical fields. Recent progress in molecular biology has led to the development of gene therapy as a new strategy to treat a variety of cardiovascular diseases using angiogenic growth factors such as vascular endothelial growth factor (VEGF). Therapeutic angiogenesis using angiogenic growth factors is expected to be a new treatment for patients with severe ischemic heart or peripheral arterial disease.     

Role of image-guided vascular intervention in therapeutic angiogenesis translational research

Therapeutic angiogenesis, the process of growing collateral blood vessels to better perfuse ischemic tissue, has been hailed as an up-and-coming treatment for symptomatic lower-extremity peripheral arterial occlusive disease. A minimally invasive durable treatment would be welcome since current treatment options for this disease carry high risk, limited efficacy or limited durability. Unfortunately, as evidenced by disappointing results in multiple clinical trials, therapeutic angiogenesis has yet to deliver in humans the success it has seen in animal models. In this review, we discuss the challenges of translating therapeutic angiogenesis into effective clinical treatments for lower-extremity peripheral arterial occlusive disease and we highlight the role that experts in image-guided vascular interventions can play in advancing the field.     

Role of image-guided vascular intervention in therapeutic angiogenesis translational research

Therapeutic angiogenesis, the process of growing collateral blood vessels to better perfuse ischemic tissue, has been hailed as an up-and-coming treatment for symptomatic lower-extremity peripheral arterial occlusive disease. A minimally invasive durable treatment would be welcome since current treatment options for this disease carry high risk, limited efficacy or limited durability. Unfortunately, as evidenced by disappointing results in multiple clinical trials, therapeutic angiogenesis has yet to deliver in humans the success it has seen in animal models. In this review, we discuss the challenges of translating therapeutic angiogenesis into effective clinical treatments for lower-extremity peripheral arterial occlusive disease and we highlight the role that experts in image-guided vascular interventions can play in advancing the field.     

Gene therapy for cardiovascular disease: the potential of VEGF

The quest for new therapeutic options and the recent exponential explosion in our knowledge of genetics have led to active interest and research into gene therapy. One area of gene therapy that has generated much debate and controversy is the use of vascular endothelial growth factor (VEGF) for therapeutic angiogenesis for palliative intent, and for the prevention of restenosis following percutaneous revascularization in coronary and peripheral arterial disease. This review highlights the development in VEGF gene therapy in the last 12 to 18 months, particularly the results from randomized, double-blind, placebo-controlled phase I and II studies that have evolved from encouraging results from animal models and early pilot studies in humans.     

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.     

Therapeutic angiogenesis for myocardial ischemia

Therapeutic angiogenesis offers promise as a novel treatment for ischemic heart disease, particularly for patients who are not candidates for current methods of revascularization. The goal of treatment is both relief of symptoms of coronary artery disease and improvement of cardiac function by increasing perfusion to the ischemic region. Protein-based therapy with cytokines including vascular endothelial growth factor and fibroblast growth factor demonstrated functionally significant angiogenesis in several animal models. However, clinical trials have yielded largely disappointing results. The attenuated angiogenic response seen in clinical trials of patients with coronary artery disease may be due to multiple factors including endothelial dysfunction, particularly in the context of advanced atherosclerotic disease and associated comorbid conditions, regimens of single agents, as well as inefficiencies of current delivery methods. Gene therapy has several advantages over protein therapy and recent advances in gene transfer techniques have improved the feasibility of this approach. The safety and tolerability of therapeutic angiogenesis by gene transfer has been demonstrated in phase I clinical trials. The utility of therapeutic angiogenesis by gene transfer as a treatment option for ischemic cardiovascular disease will be determined by adequately powered, randomized, placebo-controlled Phase II and III clinical trials. Cell-based therapies offer yet another approach to therapeutic angiogenesis. Although it is a promising therapeutic strategy, additional preclinical studies are warranted to determine the optimal cell type to be administered, as well as the optimal delivery method. It is likely the optimal treatment will involve multiple agents as angiogenesis is a complex process involving a large cascade of cytokines, as well as cells and extracellular matrix, and administration of a single factor may be insufficient. The promise of therapeutic angiogenesis as a novel treatment for no-option patients should be approached with cautious optimism as the field progresses.     

血管内支架置入治疗周围血管疾病的应用研究

目的：探讨血管内支架置入治疗周围血管疾病的应用价值。材料与方法：16例周围血管狭窄或闭塞的患者及2例外伤性周围血管损伤的患者。15例为髂动脉或股动脉动脉硬化所致的血管狭窄或闭塞，1例为左锁骨下动脉开口处动脉硬化所致的血管狭窄，1例为右肱动脉上段外伤性动脉瘤，1例为外伤性右锁骨下动－静脉瘘。16例周围血管狭窄或闭塞的患者，采用经皮穿刺溶栓治疗，球囊导管血管内成形（PTA）及血管内支架置入进行治疗，2例外伤性血管损伤的患者，采用经皮穿刺带膜血管内支架置入进行治疗。结果：18例患者经溶栓治疗，血管内成形（PTA）及血管内支架置入术治疗后，闭塞血管重新开通，损伤血管修复，血液动力学恢复正常。未发生并发症。结论：血管内支架置入治疗周围血管疾病具有较高的临床应用价值。     

Wound therapy with autologous bone marrow stem cells in diabetic patients with ischaemia-induced tissue ulcers affecting the lower limbs

Previous studies suggest that autologous transplantation of bone marrow mononuclear cells is safe and effective in inducing therapeutic angiogenesis in patients with peripheral arterial occlusive disease (PAOD). Here we discuss a multidisciplinary approach to treating PAOD with a focus on the use of angiological diagnostic tools. We conclude that our autologous stem cell therapy is working in this patient and it is a potential new therapeutic option for diabetic patients with chronic foot ulcers induced by critical limb ischaemia.     

Therapeutic angiogenesis induced by human hepatocyte growth factor gene in rat and rabbit hindlimb ischemia models: preclinical study for treatment of peripheral arterial disease

Hepatocyte growth factor (HGF) exclusively stimulates the growth of endothelial cells without replication of vascular smooth muscle cells, and acts as a survival factor against endothelial cell death. Recently, a novel therapeutic strategy for ischemic diseases using angiogenic growth factors to expedite and/or augment collateral artery development has been proposed. We have previously reported that intra-arterial administration of recombinant HGF induced angiogenesis in a rabbit hindlimb ischemia model. In this study, we examined the feasibility of gene therapy using HGF to treat peripheral arterial disease rather than recombinant therapy, due to its disadvantages. Initially, we examined the transfection of 'naked' human HGF plasmid into a rat hindlimb ischemia model. Intramuscular injection of human HGF plasmid resulted in a significant increase in blood flow as assessed by laser Doppler imaging, accompanied by the detection of human HGF protein. A significant increase in capillary density was found in rats transfected with human HGF as compared with control vector, in a dose-dependent manner (P < 0.01). Importantly, at 5 weeks after transfection, the degree of angiogenesis induced by transfection of HGF plasmid was significantly greater than that caused by a single injection of recombinant HGF. As an approach to human gene therapy, we also employed a rabbit hindlimb ischemia model as a preclinical study. Naked HGF plasmid was intramuscularly injected in the ischemic hindlimb of rabbits, to evaluate its angiogenic activity. Intramuscular injection of HGF plasmid once on day 10 after surgery produced significant augmentation of collateral vessel development on day 30 in the ischemia model, as assessed by angiography (P < 0.01). Serial angiograms revealed progressive linear extension of collateral arteries from the origin stem artery to the distal point of the reconstituted parent vessel in HGF-transfected animals. In addition, a significant increase in blood flow was assessed by a Doppler flow wire and the ratio in blood pressure of the ischemic limb to the normal limb was observed in rabbits transfected with HGF plasmid as compared with rabbits transfected with control vector (P < 0.01). Overall, intramuscular injection of naked human HGF plasmid induced therapeutic angiogenesis in rat and rabbit ischemic hindlimb models, as potential therapy for peripheral arterial disease.     

Gene therapy of cardiovascular disease

Coronary and peripheral artery diseases are highly prevalent and characterized by an unmet requirement for medical treatment in the more advanced stages. These shortcomings comprise the requirement for vessel regeneration using therapeutic angiogenesis as well as the prevention of post-angioplasty restenosis using local gene therapy. Both therapeutic angiogenesis and gene therapy to prevent post-angioplasty restenosis have undergone extensive research in the past 17 years and have led to a number of phase II clinical trials and a phase III approval trial. The development of therapeutic strategies based on gene therapy over the last 7 years is reviewed, including data from animal studies as well as phase II clinical trials.     

Stimulation of collateral artery growth: a potential treatment for peripheral artery disease

In the course of peripheral artery occlusive disease, blood flow to peripheral tissue progressively decreases in a substantial portion of patients, leading to insufficient oxygenation and to the occurrence of claudication or critical limb ischemia. Arteriogenesis (collateral artery growth) is a powerful natural mechanism by which large conductance vessels develop that circumvent sites of obstruction. Promising experimental data on both hypoxia-driven angiogenesis as well as monocyte-orchestrated arteriogenesis have raised high hopes for clinical application. Both endothelial growth factors to stimulate angiogenesis (i.e., capillary growth) and monocyte-attracting or -activating substances to stimulate arteriogenesis, have been proposed as potential new therapeutic agents. However, transferring the promising experimental results into clinical practice has been more cumbersome than initially anticipated. Some recent clinical studies are now focusing more specifically on the stimulation of arteriogenesis. This review will critically evaluate the results of preclinical and clinical investigations on the stimulation of vascular growth, focusing specifically on the peripheral circulation.     

Therapeutic angiogenesis by stem cell transplantation

The prevalence of peripheral arterial disease(PAD) is increasing with reference to the life style related disease. Up to one third of patients are not susceptible to traditional revascularization. Therefore, new strategies are needed to offer these patients a viable therapeutic option. The discovery of endothelial progenitor cells (EPCs) in human peripheral blood advanced the field of cell-based therapeutics for many pathological conditions. Bone-marrow derived stem and progenitor cells have been identified as a potential new therapeutic option to induce angiogenesis. However, the mechanism by which cell therapy improves tissue ischemia remains obscure. The present study showed that angiogenic cytokines, especially IL-1beta, were associated with the response to treatment. It is likely that muscle cells but not implanted cells are a major source of angiogenic cytokines in ischemic limbs, thereby promoting neovascularization in ischemic tissues.     

Gene and other biological therapies for vascular diseases

Summary— Gene transfer and antisense therapy offer novel approaches to the study and treatment of vascular diseases. The localized nature of vascular diseases like restenosis has made the application of genetic material an attractive therapeutic option. Viral and nonviral vectors have been developed to facilitate the entry of foreign DNA or RNA into cells. Vector improvement and production, demonstration of vector safety and demonstration of therapeutic efficacy are among the main present challenges. Various strategies have already been shown to be successful in preventing restenosis in animal models and include: the transfer of the herpes simplex virus thymidine kinase associated with ganciclovir; transfection of the cell cycle regulatory genes encoding for the active form of retinoblastoma gene product (Rb) or the cyclin-dependant kinase inhibitor p21, and antisense therapy. Therapeutic angiogenesis using gene transfer is a new strategy for the treatment of severe limb ischemia. Transfection of DNA encoding for the vascular endothelial growth factor has resulted in increasing collateral flow in animal models of peripheral ischemia. This approach is currently being investigated in a clinical trial in patients with distal ischemia. Other potential targets for genetic treatment in cardiovascular diseases include thrombosis, extracellular matrix synthesis and lipid metabolism.     

间充质干细胞的成血管作用及其临床应用

间充质干细胞（mesenchymal stem cells,MSC）作为具有多向分化能力的成体干细胞,在体外培养中可以被诱导分化为心肌细胞和血管内皮细胞。体内实验研究表明,MSC具有明显的促进血管生成作用,可从根本上阻断和逆转缺血损伤的病理过程,因此MSC在缺血性心脏病的治疗中具有潜在的应用前景。近年来随着研究的不断深入,相关研究已取得令人瞩目的结果,为此本文针对MSC的成血管作用及其临床应用作一综述,讨论的问题包括有MSC的基本生物特征,MSC的成血管作用,MSC治疗缺血性心脏病的临床前研究及其应用前景等。     

Combinatorial therapy with three‐dimensionally cultured adipose‐derived stromal cells and self‐assembling peptides to enhance angiogenesis and preserve cardiac function in infarcted hearts

Even though stem cell therapy is a promising angiogenic strategy to treat ischaemic diseases, including myocardial infarction (MI), therapeutic efficacy is limited by low survival and retention of transplanted cells in ischaemic tissues. In addition, therapeutic angiogenesis depends on stimulating host angiogenesis with paracrine factors released by transplanted cells rather than on direct blood vessel formation by transplanted cells. In the present study, to overcome these limitations and to enhance the therapeutic efficacy of MI treatment, combinatorial therapy with three‐dimensional cell masses (3DCMs) and self‐assembling peptides (SAPs) was tested in a rat MI model. Spheroid‐type 3DCMs, which are vascular differentiation‐induced cells, were prepared by culturing human adipose‐derived stromal cells on a fibroblast growth factor‐immobilized surface. The SAPs were used as the carrier material to increase engraftment of transplanted cells. After coronary artery ligation, 3DCMs were combined with SAPs and were transplanted into ischaemic lesions. The therapeutic potential was evaluated 4 weeks after treatment. By combining 3DCMs and SAPs, survival and retention of transplanted cells increased threefold when compared with treatment with 3DCMs alone and transplanted cells established vascular networks in infarcted hearts. In addition, the size of the infarct in the 3DCM + SAP group was reduced to 6.09 ± 2.83% by the promotion of host angiogenesis and cardiac function was preserved, as demonstrated by a 54.25 ± 4.42% increase in the ejection fraction. This study indicates that combinatorial therapy with 3DCM and SAPs could be a promising strategy for therapeutic angiogenesis to treat MI. Copyright © 2016 John Wiley & Sons, Ltd.     

VEGF gene therapy: therapeutic angiogenesis in the clinic and beyond

Despite the enormous progress made in terms of prevention and early intervention, a pressing need remains to develop innovative therapeutic strategies for ischemic cardiovascular disorders, including acute myocardial infarction, chronic cardiac ischemia, peripheral artery disease and stroke. The induction of new blood vessel formation by delivering angiogenic genes to ischemic tissues continues to appear as a promising, alternative strategy to currently available therapies. In aspiring to induce therapeutic angiogenesis, the members of the vascular endothelial growth factor (VEGF) family have long been recognized as major molecular tools. Remarkably, VEGF family members have recently been recognized to also exert multiple, non-angiogenic effects on various cell types, including neurons, skeletal muscle and cardiac cells. Here, we critically review the VEGF-based therapies that have already reached clinical experimentation and highlight the pleiotropic activities of VEGF factors that might create new opportunities for therapeutic application.     

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.