Clinical evidence of angiogenesis after arterial gene transfer of phVEGF165 in patient with ischaemic limb

Treatment of mouse limb ischemia with an integrative hypoxia-responsive vector expressing the vascular endothelial growth factor gene

Constitutive vascular endothelial growth factor (VEGF) gene expression systems have been extensively used to treat peripheral arterial diseases, but most of the results have not been satisfactory. In this study, we designed a plasmid vector with a hypoxia-responsive element sequence incorporated into it with the phiC31 integrative system (pVHAVI) to allow long-term VEGF gene expression and to be activated under hypoxia. Repeated activations of VEGF gene expression under hypoxia were confirmed in HEK293 and C2C12 cells transfected with pVHAVI. In limb ischemic mice, the local administration of pVHAVI promoted gastrocnemius mass and force recovery and ameliorated limb necrosis much better than the group treated with hypoxia-insensitive vector, even this last group had produced more VEGF in muscle. Histological analyses carried out after four weeks of gene therapy showed increased capillary density and matured vessels, and reduced number of necrotic cells and fibrosis in pVHAVI treated group. By our study, we demonstrate that the presence of high concentration of VEGF in ischemic tissue is not beneficial or is less beneficial than maintaining a lower but sufficient and long-term concentration of VEGF locally.

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.

Potential of Novel EPO Derivatives in Limb Ischemia

Erythropoietin (EPO) has tissue-protective properties, but it increases the risk of thromboembolism by raising the haemoglobin concentration. New generation of EPO derivatives is tissue protective without the haematopoietic side effects. Preclinical studies have demonstrated their effectiveness and safety. This paper summarizes the development in EPO derivatives with emphasis on their potential use in critical limb ischaemia.

Wound healing gene therapy: cartilage regeneration induced by vascular endothelial growth factor plasmid

AIMS

The identification of growth factors and cytokines with angiogenic activity has enabled new therapeutic treatments for a variety of diseases; this concept is called therapeutic angiogenesis. The vascular endothelial growth factor (VEGF) is the most critical regulator of vascular formation. In the present study, we were interested in the therapeutic angiogenesis effect using plasmid transfer of human complementary DNA VEGF(165) (phVEGF(165)) in experimental skin and cartilage trauma.

METHODS

Ten BALB/c mice were used for cartilage injury model. At 6 weeks of age, all mice were ear-punched, resulting in 2-mm-diameter puncture through the center of both pinnae. Each mouse got phVEGF(165) injection into the first ear and vector without insert or saline injection into the second one. The healing process was followed. The hollow diameter was measured on days 0, 14, and 42. Histological sections of experimental and control pinnae were taken from days 1, 3, 5, 7, 9, 11, 13, 15, 20, and 30 after experimental injury for hematoxylin and eosin and periodic acid Schiff staining and for human VEGF immunocytochemistry. The expression of human VEGF was also checked by real-time polymerase chain reaction in formalin-fixed, paraffin-embedded tissue sections.

KEY FINDINGS

In BALB/c mouse strain, a significant angiogenesis promotion and cartilage repair were observed after phVEGF(165) injection into the punched ear area.

SIGNIFICANCE

We suggest that administering phVEGF(165) leads to faster cartilage regeneration even if not only on the angiogenic basis.

Therapeutical potential of autologous peripheral blood mononuclear cell transplantation in patients with type 2 diabetic critical limb ischemia

AIM

The aim was to evaluate the therapeutic effectiveness of granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood mononuclear cells (PBMNCs) in critical limb ischemia (CLI) of type 2 diabetic patients.

METHOD

Forty diabetic patients with CLI were enrolled and randomized to treatment and control groups. In the treatment group, the patients received subcutaneous injections of recombinant human G-CSF (30 MU/day) for 5 days to mobilize stem cells. PBMNCs were collected and transplanted by multiple intramuscular injections of 1 ml in 1-1.5-cm depth into ischemic limbs.

RESULTS

At the end of 12 weeks of follow-up, the baseline and end point results in transplant group were as follows: Fontaine score improved from 3.8±03 to 3±0.5 (P=.0001), ankle brachial pressure index increased from 0.68±0.24 to 0.87±024 (P=.001), transcutaneous oxygen increased from 33±14 mmHg to 44±10 mmHg (P=.0001), and 6-min walking distance improved from 280±82 m to 338±98 m (P=.0001). Pain score decreased from 8.2±1.3 to 5.63±1.6 (P=.001), and the number of patients with limb ulcers was reduced from 9/20 (45%) to 3/20 (15%) (P=.031). In the control group, Fontaine score, 6-min walking distance, and pain score were improved; ankle brachial pressure index and transcutaneous oxygen pressure were not improved. The number of patients with limb ulcers did not change in the control group. There are improvement in amputation rates, collateral vessel development, and number of limb ulcers healed.

CONCLUSIONS

These results indicate that the autologous transplantation of G-CSF that mobilized PBMNCs in CLI diabetic patients is safe and effective in patient compliant reduction and improved perfusion.

Nonviral delivery of genetic medicine for therapeutic angiogenesis

Genetic medicines that induce angiogenesis represent a promising strategy for the treatment of ischemic diseases. Many types of nonviral delivery systems have been tested as therapeutic angiogenesis agents. However, their delivery efficiency, and consequently therapeutic efficacy, remains to be further improved, as few of these technologies are being used in clinical applications. This article reviews the diverse nonviral gene delivery approaches that have been applied to the field of therapeutic angiogenesis, including plasmids, cationic polymers/lipids, scaffolds, and stem cells. This article also reviews clinical trials employing nonviral gene therapy and discusses the limitations of current technologies. Finally, this article proposes a future strategy to efficiently develop delivery vehicles that might be feasible for clinically relevant nonviral gene therapy, such as high-throughput screening of combinatorial libraries of biomaterials.

Therapeutic angiogenesis for myocardial ischemia revisited: basic biological concepts and focus on latest clinical trials

Therapeutic angiogenesis is based on the premise that the development of new blood vessels can be augmented by exogenous administration of the appropriate growth factors. Over the last years, successful preclinical studies and promising results of early clinical trials have created great excitement about the potential of therapeutic angiogenesis for patients with advanced ischemic heart disease. The authors provide an overview of the biology of angiogenesis, the basic characteristics of angiogenic factors, and the different routes of their delivery. They discuss experimental studies in animal models of myocardial ischemia and outline available clinical studies on therapeutic angiogenesis for myocardial ischemia. Related safety issues are also addressed followed by a critical perspective about the future of proangiogenic therapies for ischemic cardiovascular disorders. Despite the established proof of concept and reasonable safety, however, results of the latest trials on therapeutic angiogenesis for myocardial ischemia have provided inconsistent results and the definite means of inducing clinically useful therapeutic angiogenesis remain elusive. More studies are required to gain further insights into the biology of angiogenesis and address pharmacological limitations of current approaches of angiogenic therapy. The authors hope and envisage that in the not-too-distant future, these investigative efforts will lead to important new strategies for treatment of myocardial ischemic syndromes. Means of non-invasive individualized pharmacological therapeutic neovascularization may be the next major advance in the treatment of ischaemic heart disease.

Tissue repair driven by two different mechanisms of growth factor plasmids VEGF and NGF in mice auricular cartilage: regeneration mediated by administering growth factor plasmids

The focus of this study was to compare the role of nerve growth factor (NGF) and vascular endothelial growth factor (VEGF) in the regeneration of experimental skin and cartilage trauma. The role of VEGF in this process is known since decade; the NGF participation on this process has been first discussed within the spinal cord injury repair. We hypothesized that both VEGF and NGF induce angiogenesis and take part on the repair process. The angiogenesis response and the cartilage regeneration after phVEGF(165) plasmid and rat pcNGF plasmid administration were investigated using BALB/c mice. PhVEGF(165) and pcNFG were injected into the right mice ear and plain vector injection into the left ear the day before trauma. The next day, all mice were ear-punched, resulting in 2-mm diameter puncture through the center of both pinnae. In BALB/c mouse strain, a significantly faster cartilage repair was observed after phVEGF(165) and pcNGF injection into punched ear area in comparison to the control group. It has been shown that the healing process is after VEGF and NGF injection driven differentially. In case of VEGF is the cartilage wound repaired by induction of new chondrocytes differentiation. In the case of NGF, the regeneration is supported by immature leukocytes attracted into the punched area. The leukocytes induct angiogenesis so far indirectly by inflammation. The NGF-induced inflammation environment may be a part of mosaic creating the complete picture of regeneration.

Gene therapy in the treatment of peripheral arterial disease

BACKGROUND

Peripheral arterial disease remains a significant global health burden despite revolutionary improvements in endovascular techniques over the past decade. The durability of intervention for critical limb ischaemia is poor, and the condition is associated with high morbidity and mortality rates. To address this deficiency, alternative therapeutic options are being explored. Advances in the fields of gene therapy and therapeutic angiogenesis have led to these being advocated as potential future treatments.

METHODS

Relevant medical literature from PubMed, Embase, the Cochrane Library and Google Scholar from the inception of these databases to June 2011 was reviewed.

RESULTS

Encouraging outcomes in preclinical trials using a variety of proangiogenic growth factors have led to numerous efficacy and safety studies. However, no clinical study has shown significant benefit for gene therapy over placebo.

CONCLUSION

Identifying the optimal site for gene delivery, choice of vector and duration of treatment is needed if gene therapy is to become a credible therapeutic option for peripheral arterial disease.

Angiographic Demonstration of Neoangiogenesis after Intra-arterial Infusion of Autologous Bone Marrow Mononuclear Cells in Diabetic Patients with Critical Limb Ischemia

Critical limb ischemia in diabetic patients is associated with high rates of morbidity and mortality. Suboptimal responses to the available medical and surgical treatments are common in these patients, who also demonstrate limited vascular homeostasis. Neovasculogenesis induced by stem cell therapy could be a useful approach for these patients. Neovasculogenesis and clinical improvement were compared at baseline and at 3 and 12 months after autologous bone marrow-derived mononuclear cell (BMMNC) transplantation in diabetic patients with peripheral artery disease. We conducted a prospective study to evaluate the safety and efficacy of intra-arterial administration of autologous BMMNCs (100–400 × 106 cells) in 20 diabetic patients with severe below-the-knee arterial ischemia. Although the time course of clinical effects differed among patients, after 12 months of follow-up all patients presented a notable improvement in the Rutherford-Becker classification, the University of Texas diabetic wound scales, and the Ankle-Brachial Index in the target limb. The clinical outcome was consistent with neovasculogenesis, which was assessed at 3 months by digital subtraction angiography and quantified by MetaMorph software. Unfortunately, local cell therapy in the target limb had no beneficial effect on the high mortality rate in these patients. In diabetic patients with critical limb ischemia, intra-arterial perfusion of BMMNCs is a safe procedure that generates a significant increase in the vascular network in ischemic areas and promotes remarkable clinical improvement.

Comprehensive medical management of peripheral arterial disease

Peripheral arterial disease (PAD) is highly prevalent and is associated with high morbidity and mortality. The medical management of PAD involves a comprehensive approach to the patient with emphasis on cardiovascular risk factor modification in addition to therapies directed at treatment of limb symptoms. This manuscript will review the current status of medical therapy in management of patients with PAD.

Optimal dose of plasmid vascular endothelial growth factor for enhancement of angiogenesis in the rat brain ischemia model

Vascular endothelial growth factor (VEGF) administration has recently been assessed as a therapeutic strategy for ischemic diseases including brain ischemia because of its angiogenic effect. However, VEGF also causes detrimental adverse effects by increasing vascular permeability. This study examined whether plasmid human VEGF (phVEGF) administration induced angiogenic effects in the rat brain ischemia model caused by permanent ligation of both common carotid arteries, and investigated the occurrence of adverse effects. Administration of various doses (0-200 microg) of phVEGF in the temporal muscle was followed by encephalo-myo-synangiosis. Thirty days after treatment, the numbers and areas of capillaries per field in the extracted brains were analyzed with the National Institutes of Health Image software program. The maximal angiogenic effect occurred with a 100 microg dose of phVEGF in the numbers and areas of capillaries in the VEGF-treated brains. Histological examination showed no apparent adverse effects in the brain parenchyma even at the highest administration dose (200 microg) of phVEGF. The maximal angiogenic effect at the optimal dose of phVEGF can be considered under the threshold to cause serious adverse effects in the rat brain.

Multiple sclerosis and cerebral endothelial dysfunction: Mechanisms

Multiple sclerosis (MS) is believed to be an immune-mediated neurodegenerative disorder of the human central nervous system which usually affects younger adults with certain genetic backgrounds. The causes and cure for MS remain elusive. Based on the recent advances in our understanding of the pathogenic mechanisms of MS, it appears to represents a heterogeneous group of disorders with dissimilar pathophysiology and neuropathology. Currently, there is no unifying hypothesis to explain the pathogenesis of this complex disease. The three prevailing concepts on the pathogenesis of MS include viral, immunological, and vascular hypotheses. This review presents MS as a neuroinflammatory disease with a significant vascular component and examines the existing evidence for the role of cerebral endothelial cell dysfunction in the pathogenesis of this progressive central nervous system (CNS) inflammatory disorder.

Cardiac overexpression of human VEGF(165) by recombinant Semliki Forest virus leads to adverse effects in pressure-induced heart failure

Semliki Forest virus (SFV) is an efficient vector for cardiac gene delivery. The relatively short transgene expression induced by SFV seems appropriate for angiogenic gene therapy. We tested the effects of SFV expressing vascular endothelial growth factor (VEGF) on cardiac angiogenesis and heart failure in the mRen2 transgenic rat.Six-week-old mRen2 rats received SFV-VEGF or control virus (n=7 each) administered intracoronarily. Twelve days after transfection, cardiac capillary density and function were assessed. Capillary density in cardiac regions where SFV expression was highest had decreased by 20% in the SFV-VEGF-treated group. The decrease in capillary density was accompanied by impaired systolic function as illustrated by increased endsystolic volumes and a 34% decrease in cardiac output.We conclude that the time frame of SFV expression is sufficient to induce structural alterations, but that VEGF in mRen2 transgenic rats did not elicit the expected angiogenic effect. Rather, capillary density was decreased and subsequently cardiac function was impaired. This paradoxical finding is possibly related to the pathophysiology associated with this model and warrants caution if one is to pursue VEGF-mediated, angiogenic therapy before proceeding to a clinical setting. (Neth Heart J 2007;15:335-41.).

Identification of cis- and trans-acting genetic variants explaining up to half the variation in circulating vascular endothelial growth factor levels

RATIONALE

Vascular endothelial growth factor (VEGF) affects angiogenesis, atherosclerosis, and cancer. Although the heritability of circulating VEGF levels is high, little is known about its genetic underpinnings.

OBJECTIVE

Our aim was to identify genetic variants associated with circulating VEGF levels, using an unbiased genome-wide approach, and to explore their functional significance with gene expression and pathway analysis.

METHODS AND RESULTS

We undertook a genome-wide association study of serum VEGF levels in 3527 participants of the Framingham Heart Study, with preplanned replication in 1727 participants from 2 independent samples, the STANISLAS Family Study and the Prospective Investigation of the Vasculature in Uppsala Seniors study. One hundred forty single nucleotide polymorphism (SNPs) reached genome-wide significance (P<5×10(-8)). We found evidence of replication for the most significant associations in both replication datasets. In a conditional genome-wide association study, 4 SNPs mapping to 3 chromosomal regions were independently associated with circulating VEGF levels: rs6921438 and rs4416670 (6p21.1, P=6.11×10(-506) and P=1.47×10(-12)), rs6993770 (8q23.1, P=2.50×10(-16)), and rs10738760 (9p24.2, P=1.96×10(-34)). A genetic score including these 4 SNPs explained 48% of the heritability of serum VEGF levels. Six of the SNPs that reached genome-wide significance in the genome-wide association study were significantly associated with VEGF messenger RNA levels in peripheral blood mononuclear cells. Ingenuity pathway analyses showed found plausible biological links between VEGF and 2 novel genes in these loci (ZFPM2 and VLDLR).

CONCLUSIONS

Genetic variants explaining up to half the heritability of serum VEGF levels were identified. These new insights provide important clues to the pathways regulating circulating VEGF levels.

Plasmid-mediated gene therapy for cardiovascular disease

Gene transfer within the cardiovascular system was first demonstrated in 1989 yet, despite extensive basic-science and clinical research, unequivocal benefit in the clinical setting remains to be demonstrated. Potential reasons for this include the fact that recombinant viral vectors, used in the majority of clinical studies, have inherent problems with immunogenicity that are difficult to circumvent. Attention has turned therefore to plasmid vectors, which possess many advantages over viruses in terms of safety and ease of use, and many clinical studies have now been performed using non-viral technology. This review will provide an overview of clinical trials for cardiovascular disease using plasmid vectors, recent developments in plasmid delivery and design, and potential directions for this modality of gene therapy.

Update on biological therapies for critical limb ischemia

Gene and stem cell therapies have been shown to be safe and well tolerated. Early trial results using these therapies have had promising results on important clinical end points such as wound healing, ischemic pain, and major amputation. Despite this, there have been no pivotal trials to date that have proved the benefit of biological therapy, although there are numerous pivotal trials in progress or about to initiate enrollment. Persistent obstacles exist with current study designs that complicate the ability to successfully perform clinical critical limb ischemia trials.

Targeted gene therapy for the treatment of heart failure

Chronic heart failure is one of the leading causes of morbidity and mortality in Western countries and is a major financial burden to the health care system. Pharmacologic treatment and implanting devices are the predominant therapeutic approaches. They improve survival and have offered significant improvement in patient quality of life, but they fall short of producing an authentic remedy. Cardiac gene therapy, the introduction of genetic material to the heart, offers great promise in filling this void. In-depth knowledge of the underlying mechanisms of heart failure is, obviously, a prerequisite to achieve this aim. Extensive research in the past decades, supported by numerous methodological breakthroughs, such as transgenic animal model development, has led to a better understanding of the cardiovascular diseases and, inadvertently, to the identification of several candidate genes. Of the genes that can be targeted for gene transfer, calcium cycling proteins are prominent, as abnormalities in calcium handling are key determinants of heart failure. A major impediment, however, has been the development of a safe, yet efficient, delivery system. Nonviral vectors have been used extensively in clinical trials, but they fail to produce significant gene expression. Viral vectors, especially adenoviral, on the other hand, can produce high levels of expression, at the expense of safety. Adeno-associated viral vectors have emerged in recent years as promising myocardial gene delivery vehicles. They can sustain gene expression at a therapeutic level and maintain it over extended periods of time, even for years, and, most important, without a safety risk.

Hypocellularity and insufficient expression of angiogenic factors in implanted autologous bone marrow in patients with chronic critical limb ischemia

The aim of this study was to identify the clinical parameters of absolutely poor-prognosis patients with chronic critical limb ischemia (AP-CLI). Sixteen no-option CLI patients with arteriosclerosis obliterans: ASO (nine) and non-ASO patients (seven) treated with bone marrow-mononuclear cell implantation (BMI) were analyzed. There were three AP-CLI patients (all ASO). The mRNA expression of several angiogenic factors in the implanted cells was analyzed in comparison with normal donor bone marrow. To observe the response of bone marrow components to hypoxia, normal bone marrow cells were cultured for 24 h in 2.5% O(2), and mRNA expression of angiogenic factors were measured. AP-CLI patients exhibited extraordinary low bone marrow cellularity as well as the percentage of CD34-positive cells. Among angiogenic factors, only VEGF expression was maintained in response to HIF-1, while other factors such as HGF, Ang-1, PLGF, and SDF-1 decreased in the implanted bone marrow cells of the patients with CLI compared to normal bone marrow cells. HIF-1 and all of the five angiogenic factors increased in vitro in response to hypoxia. Thus it is highly likely that angiogenic factors except VEGF do not respond to chronic ischemia in bone marrow in vivo. An organ-protection system against tissue ischemia may be applied for acute hypoxia, but it may be insufficient for chronic ischemia.

Drug delivery strategies for therapeutic angiogenesis and antiangiogenesis

INTRODUCTION

Angiogenesis is essential to human biology and of great clinical significance. Excessive or reduced angiogenesis can result in, or exacerbate, several disease states, including tumor formation, exudative age-related macular degeneration (AMD) and ischemia. Innovative drug delivery systems can increase the effectiveness of therapies used to treat angiogenesis-related diseases.

AREAS COVERED

This paper reviews the basic biology of angiogenesis, including current knowledge about its disruption in diseases, with the focus on cancer and AMD. Anti- and proangiogenic drugs available for clinical use or in development are also discussed, as well as experimental drug delivery systems that can potentially improve these therapies to enhance or reduce angiogenesis in a more controlled manner.

EXPERT OPINION

Laboratory and clinical results have shown pro- or antiangiogenic drug delivery strategies to be effective in drastically slowing disease progression. Further research in this area will increase the efficacy, specificity and duration of these therapies. Future directions with composite drug delivery systems may make possible targeting of multiple factors for synergistic effects.

Buerger's Disease (Thromboangiitis Obliterans)- Management by Ilizarov's Technique of Horizontal Distraction. A Retrospective Study of 60 Cases

In Buerger's disease conservative treatment is questionable. Arterial reconstructive surgery is not feasible and sympathectomy has limited role. Progression of the disease invariably leads to amputation. Ilizarov's method increases the vascularity of the ischaemic limb. Retrospective analysis of Ilizarov's technique in 60 patients was done. Immediate results took into account rest pain, colour of skin, venous return, temperature, pulse oxymeter measured oxygen saturation and ulcer/amputation stump wound healing. Early and late results took into account rest pain, healing of ulcers/amputation stump with or without plastic coverage, claudication distance, resumption of previous occupation and domestic ambulation. The mean follow up of patients was 63 months. Immediate results were promising except two amputations. Early result were excellent to good in 56 and late results were excellent to good in 48 patients. Deterioration had significant correlation with smoking. Ilizarov's method is an excellent and cheap procedure in treatment of Buerger's disease.

Phase I/IIa clinical trial of therapeutic angiogenesis using hepatocyte growth factor gene transfer to treat critical limb ischemia

OBJECTIVE

To evaluate the safety and feasibility of intramuscular gene transfer using naked plasmid DNA-encoding hepatocyte growth factor (HGF) and to assess its potential therapeutic benefit in patients with critical limb ischemia.

METHODS AND RESULTS

Gene transfer was performed in 22 patients with critical limb ischemia by intramuscular injection of HGF plasmid, either 2 or 4 mg, 2 times. Safety, ankle-brachial index, resting pain on a 10-cm visual analog scale, wound healing, and walking distance were evaluated before treatment and at 2 months after injection. No serious adverse event caused by gene transfer was detected over a follow-up of 6 months. Of particular importance, no peripheral edema, in contrast to that seen after treatment with vascular endothelial growth factor, was observed. In addition, the systemic HGF protein level did not increase during the study. At 2 months after gene transfer, the mean ± SD ankle-brachial index increased from 0.46 ± 0.08 to 0.59 ± 0.13 (P<0.001), the mean ± SD size of the largest ischemic ulcers decreased from 3.08 ± 1.54 to 2.32 ± 1.88 cm (P=0.007), and the mean ± SD visual analog scale score decreased from 5.92 ± 1.67 to 3.04 ± 2.50 cm (P=0.001). An increase in ankle-brachial index by >0.1, a reduction in ulcer size by >25%, and a reduction in visual analog scale score by >2 cm at 2 months after gene transfer were observed in 11 (64.7%) of 17 limbs, 18 (72%) of 25 ulcers, and 8 (61.5%) of 13 limbs, respectively.

CONCLUSIONS

Intramuscular injection of naked HGF plasmid is safe and feasible and can achieve successful improvement of ischemic limbs as sole therapy.

Sequential delivery of vascular endothelial growth factor and sphingosine 1-phosphate for angiogenesis

Angiogenesis is an organized series of events, beginning with vessel destabilization, followed by endothelial cell re-organization, and ending with vessel maturation. Vascular endothelial growth factor (VEGF) aids in vascular permeability and endothelial cell recruitment while sphingosine 1-phosphate (S1P) stimulates vascular stability. Accordingly, VEGF may inhibit vessel stabilization while S1P may inhibit endothelial cell recruitment. For this reason, we created a new externally-regulated delivery model that not only permits sustained release of bioactive factors, but also temporal separation of the delivery of growth factors. Using this model, sequential delivery of factors was first confirmed in vitro with associated endothelial cells responding in a dose dependent manner. Furthermore, using a modified murine Matrigel plug model, it is apparent that delivery strategies where VEGF presentation is temporally separated from S1P presentation not only led to greater recruitment of endothelial cells, but also higher maturation index of associated vessels.

Release kinetics of VEGF165 from a collagen matrix and structural matrix changes in a circulation model

Background

Current approaches in bone regeneration combine osteoconductive scaffolds with bioactive cytokines like BMP or VEGF. The idea of our in-vitro trial was to apply VEGF₁₆₅ in gradient concentrations to an equine collagen carrier and to study pharmacological and morphological characteristics of the complex in a circulation model.

Methods

Release kinetics of VEGF₁₆₅ complexed in different quantities in a collagen matrix were determined in a circulation model by quantifying protein concentration with ELISA over a period of 5 days. The structural changes of the collagen matrix were assessed with light microscopy, native scanning electron microscopy (SEM) as well as with immuno-gold-labelling technique in scanning and transmission electron microscopy (TEM).

Results

We established a biological half-life for VEGF₁₆₅ of 90 minutes. In a half-logarithmic presentation the VEGF₁₆₅ release showed a linear declining gradient; the release kinetics were not depending on VEGF₁₆₅ concentrations. After 12 hours VEGF release reached a plateau, after 48 hours VEGF₁₆₅ was no longer detectable in the complexes charged with lower doses, but still measurable in the 80 μg sample. At the beginning of the study a smear layer was visible on the surface of the complex. After the wash out of the protein in the first days the natural structure of the collagen appeared and did not change over the test period.

Conclusions

By defining the pharmacological and morphological profile of a cytokine collagen complex in a circulation model our data paves the way for further in-vivo studies where additional biological side effects will have to be considered. VEGF₁₆₅ linked to collagen fibrils shows its improved stability in direct electron microscopic imaging as well as in prolonged release from the matrix. Our in-vitro trial substantiates the position of cytokine collagen complexes as innovative and effective treatment tools in regenerative medicine and and may initiate further clinical research.

Exploring the molecular mechanisms of OSU-03012 on vascular smooth muscle cell proliferation

Restenosis is resulted from the proliferation and migration of vascular smooth muscle cells (VSMCs) from the arterial media into the intima within the vessel lumen following percutaneous transluminal coronary angioplasty (PTCA). OSU-03012, a synthetic compound (2-amino-N-{4-[5-(2-phenanthrenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]-phenyl} acetamide) acting as a PDK-1 inhibitor, is used as an apoptosis-promoting anticancer drug. However, whether OSU-03012 can inhibit VSMC proliferation and migration following PTCA remains unclear. In this study, we used A10 smooth muscle cells cultured in 10% FBS for stimulating proliferation and evaluated the inhibitory effects of OSU-03012 on cell proliferation and migration. The data demonstrated that OSU-03012 dose-dependently inhibited A10 cell proliferation examined by Trypan blue, MTT and morphological alteration assays, and inhibited the levels of proliferation-related proteins, proliferating cell nuclear antigen (PCNA), phosphorylated ERK examined by western blotting. Additionally, 10 μM OSU-03012 also enhanced apoptosis examined using DAPI assay by regulating apoptosis-related proteins. Furthermore, compared with the control group, A10 cells treated with 10 μM OSU-03012 showed a lower number of migrating cells examined by Boyden Chamber assay, and a dose-dependently reduced NFκB-dependent and interferon-stimulated response element (ISRE) promoter luciferase activities, implying the anti-migration and anti-inflammation effects of OSU03012. Taken together, this study provides insights into the pharmacological mechanisms of OSU-03012 in preventing smooth muscle cell proliferation, migration, and inflammation supporting the novel discovery of OSU-03012 as an adjuvant therapy for balloon injury-induced restenosis.

Angiomyeloproliferative lesions following autologous stem cell therapy

Some reports suggest that autologous hematopoietic stem cell transplantation holds potential for treatment of renal diseases such as lupus nephritis, but the safety of delivering various stem cell types (hematopoietic, mesenchymal, and endothelial precursors) is not well established. Here, we report a case of lupus nephritis treated by direct renal injection of autologous stem cells recovered from peripheral blood. The patient developed masses at the sites of injection and hematuria. We suspected transitional cell carcinoma but nephrectomy revealed that the masses were angiomyeloproliferative lesions. We believe that this previously undescribed pathologic entity is stem cell-derived or -induced. The biologic potential, including the neoplastic potential, of this lesion is unknown. This case illustrates that the development of angiomyeloproliferative lesions is a possible complication of stem cell therapy.

High-throughput flow cytometry purification of transduced progenitors expressing defined levels of vascular endothelial growth factor induces controlled angiogenesis in vivo

Delivery of therapeutic genes by genetically modified progenitors is a powerful tool for regenerative medicine. However, many proteins remain localized within or around the expressing cell, and heterogeneous expression levels can lead to reduced efficacy or increased toxicity. For example, the matrix-binding vascular endothelial growth factor (VEGF) can induce normal, stable, and functional angiogenesis or aberrant angioma growth depending on its level of expression in the microenvironment around each producing cell, and not on its total dose. To overcome this limitation, we developed a flow cytometry-based method to rapidly purify transduced cells expressing desired levels of a therapeutic transgene. Primary mouse myoblasts were transduced with a bicistronic retrovirus expressing VEGF linked to a nonfunctional, truncated form of the syngenic molecule CD8a. By using a clonal population uniformly expressing a known VEGF level as a reference, cells producing similar VEGF amounts were rapidly sorted from the primary population on the basis of their CD8a fluorescence intensity. A single round of sorting with a suitably designed gate yielded a purified population that induced robust, normal, and stable angiogenesis, and completely avoided angioma growth, which was instead always caused by the heterogeneous parent population. This clinically applicable high-throughput technique allowed the delivery of highly controlled VEGF levels in vivo, leading to significantly improved safety without compromising efficacy. Furthermore, when applied to other suitable progenitor populations, this technique could help overcome a significant obstacle in the development of safe and efficacious vascularization strategies in the fields of regenerative medicine and tissue engineering.

[Renal cell carcinoma: antiangiogenic therapies and management of the complications. A case report]

Direct side effects of the inhibition of activation of VEGF receptors are well known and could be easily explained (HTA). The indirect toxicity of the inhibitors of tyrosinekinases is much less known and several hypotheses appear. Usually, the common side effects of the inhibitors of tyrosine-kinases can be easily managed and are reversible when the treatment is stopped. Their management is essentially based on prevention measures. It is necessary to stop definitively or temporarily the treatment in case of intensification of pre-existing comorbidities or side effects of rank 3 or 4. There is no predictive factor of treatment toxicity and, at the moment, there is thus no indication in a previous dose adaptation.

Synergistic effect of vascular endothelial growth factor and granulocyte colony-stimulating factor double gene therapy in mouse limb ischemia

BACKGROUND

Vascular endothelial growth factor (VEGF) has mostly been tested to treat ischemic diseases, although the outcomes obtained are not satisfactory. Our hypothesis is that the local transient expression of VEGF and stem cell mobilizer granulocyte colony-stimulating factor (G-CSF) genes in ischemic limbs can complement their activities and be more efficient for limb recovery.

METHODS

Limb ischemia was surgically induced in mice and 50 microg of VEGF and/or G-CSF genes were locally transferred by electroporation. After 3-4 weeks, evidence of necrosis by visual inspection, capillary density, muscle mass, muscle force and hematopoietic cell mobilization were evaluated.

RESULTS

After 4 weeks, 70% and 90% of the animals of the ischemic group (IG) and VEGF-treated group (VG), respectively, presented limb necrosis, in contrast to only 10% observed in the group of mice treated with both VEGF and G-CSF genes (VGG). Recovery of muscle mass and muscle force was higher than 60% in the VGG compared to the non-ischemic group. The mobilization of Sca1+ cells and neutrophils was also higher in the VGG, which may explain the lower level of necrosis observed in this group (22%, in contrast to 70% in the IG). Capillary density and degree of fibrosis were determined in weeks 3 and 4, and also showed a clear benefit as a result of the use of the G-CSF and VEGF genes together.

CONCLUSIONS

Gene therapy using VEGF and G-CSF demonstrated a synergistic effect promoting vessel and tissue repair in mouse hind limb ischemia.

Extracellular matrix molecules: potential targets in pharmacotherapy

The extracellular matrix (ECM) consists of numerous macromolecules classified traditionally into collagens, elastin, and microfibrillar proteins, proteoglycans including hyaluronan, and noncollagenous glycoproteins. In addition to being necessary structural components, ECM molecules exhibit important functional roles in the control of key cellular events such as adhesion, migration, proliferation, differentiation, and survival. Any structural inherited or acquired defect and/or metabolic disturbance in the ECM may cause cellular and tissue alterations that can lead to the development or progression of disease. Consequently, ECM molecules are important targets for pharmacotherapy. Specific agents that prevent the excess accumulation of ECM molecules in the vascular system, liver, kidney, skin, and lung; alternatively, agents that inhibit the degradation of the ECM in degenerative diseases such as osteoarthritis would be clinically beneficial. Unfortunately, until recently, the ECM in drug discovery has been largely ignored. However, several of today's drugs that act on various primary targets affect the ECM as a byproduct of the drugs' actions, and this activity may in part be beneficial to the drugs' disease-modifying properties. In the future, agents and compounds targeting directly the ECM will significantly advance the treatment of various human diseases, even those for which efficient therapies are not yet available.

Prostanoids for critical limb ischaemia

BACKGROUND

Peripheral arterial occlusive disease (PAOD) is a common cause of morbidity and mortality due to cardiovascular diseases in the general population. While numerous treatments have been adopted for different disease stages, there is no option other than amputation for patients presenting with critical limb ischaemia (CLI), unsuitable for rescue or reconstructive intervention.

OBJECTIVES

To determine the effectiveness and safety of prostanoids in patients presenting with CLI.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their trials register (last searched October 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (last searched 2009, Issue 4) for publications describing randomised controlled trials (RCTs) of prostanoids for CLI. We ran additional searches in MEDLINE, EMBASE, LILACS, and SciSearch, and we also contacted pharmaceutical companies and experts, in order to identify unpublished data and trials still underway.

SELECTION CRITERIA

Randomised controlled trials describing efficacy and safety of prostanoids compared with placebo or other pharmacological control treatments, in patients presenting with CLI, without chance of rescue or reconstructive intervention.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, assessed trials for eligibility and methodological quality, and extracted data. Disagreements were resolved by consensus or by the third author.

MAIN RESULTS

We retrieved 532 citations which after the first screening resulted in 111 potential studies. Finally, after exclusion of studies of poor quality and a lack of sufficient information, 20 trials were included in the review.Prostanoids seem to have efficacy regarding rest-pain relief (risk ratio (RR) 1.32, 95% confidence interval (CI) 1.10 to 1.57; P = 0.003), and ulcer healing (RR 1.54, 95% CI 1.22 to 1.96). Iloprost also shows favourable results regarding major amputations (RR 0.69, 95% CI 0.52 to 0.93). The more frequently reported adverse events when using prostanoids were headache, facial flushing, nausea, vomiting and diarrhoea.

AUTHORS' CONCLUSIONS

Despite some positive results regarding rest-pain relief, ulcer healing and amputations, there is no conclusive evidence based on this meta-analysis of the long-term effectiveness and safety of different prostanoids in patients with CLI. Further well-conducted, high quality randomised double-blinded trials should be performed.

Improving regenerating potential of the heart after myocardial infarction: factor-based approach

The emerging evidence that the heart has the potential to regenerate, albeit not ideally, has stimulated considerable interest in the field of cardiac regenerative medicine. Several lines of research demonstrated that factor-based therapy is feasible and effective, whether it is used independently or as an adjunct to cell therapy. The ultimate goal of the factor-based approach is to improve the regenerating potential of the heart as a means to treat patients with cardiovascular disease. This article reviews recent approaches involving factor-based therapy for cardiac repair and regeneration including some of the advantages of this type of therapy as well as some of the hurdles that must be overcome before this therapeutic approach becomes a standard part of clinical medicine.

Regenerative therapy in peripheral artery disease

Patients with peripheral artery disease (PAD) and critical limb ischemia are the main candidates for limb amputations and have a poor life expectancy. Frequently, these patients are not eligible for either surgical or percutaneous interventions aimed at mechanical revascularization. Therefore, new strategies need to be identified to offer these patients a viable therapeutic option. Gene and cell therapy hold great promise for the treatment of peripheral vascular diseases because, in animal models, local delivery of growth factors and endothelial progenitor cells result in new blood vessel formation and regeneration of ischemic tissues. In this article, are reviewed phase I and phase II gene, and cell therapy clinical trials in patients with PAD.

Endovascular treatment of peripheral vascular disease

Peripheral arterial disease (PAD) affects about 27 million people in North America and Europe, accounting for up to 413,000 hospitalizations per year with 88,000 hospitalizations involving the lower extremities and 28,000 involving embolectomy or thrombectomy of lower limb arteries. Many patients are asymptomatic and, among symptomatic patients, atypical symptoms are more common than classic claudication. Peripheral arterial disease also correlates strongly with risk of major cardiovascular events, and patients with PAD have a high prevalence of coexistent coronary and cerebrovascular disease. Because the prevalence of PAD increases progressively with age, PAD is a growing clinical problem due to the increasingly aged population in the United States and other developed countries. Until recently, vascular surgical procedures were the only alternative to medical therapy in such patients. Today, endovascular practice, percutaneous transluminal angioplasty with or without stenting, is used far more frequently for all types of lower extremity occlusive lesions, reflecting the continuing advances in imaging techniques, angioplasty equipment, and endovascular expertise. The role of endovascular intervention in the treatment of limb-threatening ischemia is also expanding, and its promise of limb salvage and symptom relief with reduced morbidity and mortality makes percutaneous transluminal angioplasty/stenting an attractive alternative to surgery and, as most endovascular interventions are performed on an outpatient basis, hospital costs are cut considerably. In this monograph we discuss current endovascular intervention for treatment of occlusive PAD, aneurysmal arterial disease, and venous occlusive disease.

IRES-based vector coexpressing FGF2 and Cyr61 provides synergistic and safe therapeutics of lower limb ischemia

Due to the lack of an adequate conventional therapy against lower limb ischemia, gene transfer for therapeutic angiogenesis is seen as an attractive alternative. However, the possibility of side effects, due to the expression of large amounts of angiogenic factors, justifies the design of devices that express synergistic molecules in low controlled doses. We have developed an internal ribosome entry site (IRES)-based bicistronic vector expressing two angiogenic molecules, fibroblast growth factor 2 (FGF2), and Cyr61. Through electrotransfer into the ApoE(-/-) mice hindlimb ischemic muscle model, we show that the IRES-based vector gives more stable expression than either monocistronic plasmid. Furthermore, laser Doppler analysis, arteriography, and immunochemistry clearly show that the bicistronic vector promotes a more abundant and functional revascularization than the monocistronic vectors, despite the fact that the bicistronic system produces 5-10 times less of each angiogenic molecule. Furthermore, although the monocistronic Cyr61 vector accelerates B16 melanoma growth in mice, the bicistronic vector is devoid of such side effects. Our results show an active cooperation of FGF2 and Cyr61 in therapeutic angiogenesis of hindlimb ischemia, and validate the use of IRES-based bicistronic vectors for the coexpression of controlled low doses of therapeutic molecules, providing perspectives for a safer gene therapy of lower limb ischemia.

Human studies of angiogenic gene therapy

Despite significant advances in medical, interventional, and surgical therapy for coronary and peripheral arterial disease, the burden of these illnesses remains high. To address this unmet need, the science of therapeutic angiogenesis has been evolving for almost two decades. Early preclinical studies and phase I clinical trials achieved promising results with growth factors administered as recombinant proteins or as single-agent gene therapies, and data accumulated through 10 years of clinical trials indicate that gene therapy has an acceptable safety profile. However, more rigorous phase II and phase III clinical trials have failed to unequivocally demonstrate that angiogenic agents are beneficial under the conditions and in the patients studied to date. Investigators have worked to understand the biology of the vascular system and to incorporate their findings into new treatments for patients with ischemic disease. Recent gene- and cell-therapy trials have demonstrated the bioactivity of several new agents and treatment strategies. Collectively, these observations have renewed interest in the mechanisms of angiogenesis and deepened our understanding of the complexity of vascular regeneration. Gene therapy that incorporates multiple growth factors, approaches that combine cell and gene therapy, and the administration of "master switch" agents that activate numerous downstream pathways are among the credible and plausible steps forward. In this review, we examine the clinical development of angiogenic gene therapy, summarize several of the lessons learned during the conduct of these trials, and suggest how this prior experience may guide the conduct of future preclinical investigations and clinical trials.

Implications of vascular endothelial growth factor for postischemic neurovascular remodeling

Neurovascular remodeling has been recently recognized as a promising target for neurologic therapies. Hopes have emerged that, by stimulating vessel growth, it may be possible to stabilize brain perfusion, and at the same time promote neuronal survival, brain plasticity, and neurologic recovery. In this review, we outline the role of vascular endothelial growth factor (VEGF) in the ischemic brain, analyzing how this growth factor contributes to brain remodeling. Studies with therapeutic VEGF administration resulted in quite variable results depending on the route and time point of delivery. Local VEGF administration consistently enhanced neurologic recovery, whereas acute intravenous delivery exacerbated brain infarcts due to enhanced brain edema. Future studies should answer the following questions: (1) whether increased vessel density translates into improvements in blood flow in the hemodynamically compromised brain; (2) how VEGF influences brain plasticity and contributes to motor and nonmotor recovery; (3) what are the actions of VEGF not only in young animals with preserved vasculature, on which previous studies have been conducted, but also in aged animals and in animals with preexisting atherosclerosis; and (4) whether the effects of VEGF can be mimicked by pharmacological compounds or by cell-based therapies. Only on the basis of such information can more definite conclusions be made with regard to whether the translation of therapeutic angiogenesis into clinics is promising.