Vascular endothelial growth factor expression, angiogenesis, and necrosis in renal cell carcinomas

Rapidly growing tumors often develop necrosis. In the present study the expression of vascular endothelial growth factor (VEGF) was investigated and compared to microvessel density and necrosis of renal cell carcinomas. In the tumor-host interface the microvessel density was significantly increased compared to central tumor areas. Tumor necrosis was associated with a decrease of microvessel density and an increase of the VEGF protein expression within the perinecrotic rim. VEGF protein was focally upregulated in vital tumor tissue. An increase of the apoptotic rate of endothelia and vital tumor tissue in tumors with necrosis could not be detected. VEGF(121,165) mRNA was decreased in proliferatively active carcinomas compared to less proliferative tumors. Multicellular renal cell cancer spheroids as a model of chronic hypoxia developed central apoptosis but no necrosis. VEGF was upregulated in the spheroid. Tumor microvessels expressed matrix metalloproteinase -2 and -9 and an incomplete pericyte covering in comparison to tumor-free tissue indicating immature active angiogenesis. We conclude that highly proliferative renal cell carcinomas outgrow their vascular supply and develop chronic hypoxia inducing a decrease of proliferation and an increase of VEGF expression. However, chronic hypoxia does not cause significant necrosis or apoptosis. Tumor necrosis is more likely induced by acute hypoxia due to immature microvessels. Furthermore, VEGF expression associated with concomitant tumor necrosis may help identify renal cell carcinomas susceptible to antiangiogenic therapy.

Inhibition of Kirsten-ras expression in human colorectal cancer using rationally selected Kirsten-ras antisense oligonucleotides

Kirsten-ras is frequently mutated in colorectal cancers and may be an important therapeutic target, particularly because we have previously shown that acquisition of a mutation is associated with a poorer outcome. Understanding the role of Kirsten-ras and the consequences of inhibiting its activity or expression will contribute to our comprehension of colorectal cancer biology and may help to rationalize the choice of molecular targets suitable for therapeutic manipulation. Therefore we undertook a simple screen, incubating a library of oligonucleotides with Kirsten-ras mRNA and RNase H to identify an antisense oligonucleotide that effectively inhibited Kirsten-ras expression. We show for the first time in a human colon cancer cell line that inhibition of Kirsten-ras expression inhibits constitutive phosphorylation of Erk1/2, but not c-Akt, suggesting that in these cells constitutive phosphorylation of Erk 1/2 is dependent upon Kirsten-ras. Successful inhibition of Kirsten-ras had little effect on cell number or cell death and there was no evidence for accumulation of cells in any particular phase of the cell cycle. Kirsten-ras inhibition significantly reduced secretion of VEGF-A165 into the culture medium. Gene expression profiling by microarray detected altered expression of a number of genes. Of particular interest for future studies was the altered expression of genes encoding products involved in protein trafficking and the potential effects of these changes on cell adhesion. Our results suggest that, at least in this model, Kirsten-ras may contribute to malignancy predominantly through effects on angiogenesis, invasion, and metastasis, and that therapies directed at Kirsten-ras, including antisense approaches, may have particular utility through these mechanisms.

Gene therapy for gastric ulcers with single local injection of naked DNA encoding VEGF and angiopoietin-1

BACKGROUND & AIMS

Angiogenesis, formation of new capillary blood vessels, is crucial for gastroduodenal ulcer healing because it enables delivery of oxygen and nutrients to the healing site. Because angiogenesis is stimulated by vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang1), we studied whether local gene therapy with nonviral DNA encoding VEGF and/or Ang1 into the ulcer base could accelerate ulcer healing through enhanced angiogenesis.

METHODS

Gastric ulcers were induced in rats by acetic acid applied to the serosal surface of the stomach, and the site around the ulcer was injected with nonviral plasmid-encoding full-length complementary DNA (cDNA) of human recombinant (rh) VEGF165, rhAng1, or their combination. For some studies, neutralizing anti-VEGF antibody was administered.

RESULTS

Single local injection of plasmids encoding VEGF165 and Ang1 significantly increased neovascularization and accelerated ulcer healing. A neutralizing anti-VEGF antibody significantly reduced the acceleration of ulcer healing resulting from the treatment. Coinjection of both plasmids encoding rhVEGF165 and rhAng1 resulted in formation of more mature vessels and to more complete restoration of gastric glandular structures within the ulcer scar. However, this did not result in further reduction of ulcer size.

CONCLUSIONS

VEGF and Ang1 gene therapy, with limited duration of target gene expression, significantly accelerates gastric ulcer healing. Coinjection of both plasmids leads to more complete structural restoration. Inhibition of accelerated healing by a neutralizing anti-VEGF antibody indicates an essential role for VEGF and enhanced angiogenesis in ulcer healing.

Assessment of the VEGF, bFGF, aFGF and IL8 angiogenic activity in urinary bladder carcinoma, using the mice cutaneous angiogenesis test

Development of new blood vessels in solid tumors depends on changes in equilibrium between angiogenic stimulators and inhibitors. Overexpression of angiogenic growth factors has been shown in bladder carcinoma. The 'mice cutaneous angiogenesis test' is a good method for assessment of the total angiogenic potential of bladder cancer tissue. The analysis of the levels of proangiogenic factors could be useful for the choice of properly directed angiogenesis inhibitors. The aim of our study was to investigate the influence of blocking some angiogenic factors on the angiogenic activity of bladder cancer tissue. Tumor tissue obtained from 12 patients with invasive bladder carcinoma was used. Cancer tissue homogenates were incubated in the presence of specific antibodies against VEGF, bFGF, Il-8 and aFGF. Cytokine levels were determined using the ELISA test. Cutaneous angiogenesis assay in Balb/c mice was performed to detect the angiogenic activity of the tumor tissue. VEGF, bFGF and Il-8 were present in all examined cancer tissues (aFGF level was not estimated). Cytokine concentration and angiogenic activity of bladder cancer tissue showed individual variation. There was no correlation between the cytokines content in tumor tissue and the ability of this tissue to induce angiogenesis. Absorption caused significant reduction in cytokines level. The reduction of angiogenic activity was observed in the cancer tissue of 1 patient after VEGF absorption, in 3 patients' tissue homogenates after incubation with anti-aFGF and in 2 patients' homogenates after bFGF absorption. There was no reduction of angiogenic activity after Il-8 absorption.

[Effect of PCNA antisense oligooxynucleotides and VEGF antisense oligoxynucleotides on growth of hepatocellular carcinoma transplanted in nude mice]

OBJECTIVE

To study the inhibitory effect of PCNA antisense oligonucleotides or/and VEGF antisense oligonucleotides on growth of human hepatocellular carcinoma in nude mice.

METHODS

Human hepatocellular carcinoma transplanted subcutaneously in nude mice model was established, and subsequently was divided into four groups: PCNA-ASODN group, VEGF-ASODN group, combined group and control group. Different treatments were given respectively. The weigh and volume of subcutaneous tumors was measured, and the morphological changes of tumor cells was observed under microscope.

RESULTS

The growth inhibitory rate in the PCNA-ASODN group was 72.8%, 44.9% in the VEGF-ASODN group, and 87.2% in the combined group. The combined group which was treated with PCNA-ASODN and VEGF-ASODN showed more effective inhibitory than the PCNA-ASODN group or the VEGF-ASODN group respectively.

CONCLUSIONS

The growth of human hepatocellular carcinoma in nude mice can be inhibited by PCNA antisense oligonucleotides and VEGF antisense oligonucleotides respectively. Better inhibitory effect can be obtained if PCNA antisense oligonucleotides and VEGF antisense oligonucleotides are combined in use.

Biopanning and rapid analysis of selective interactive ligands

Here we introduce a new approach for the screening, selection and sorting of cell-surface-binding peptides from phage libraries. Biopanning and rapid analysis of selective interactive ligands (termed BRASIL) is based on differential centrifugation in which a cell suspension incubated with phage in an aqueous upper phase is centrifuged through a non-miscible organic lower phase. This single-step organic phase separation is faster, more sensitive and more specific than current methods that rely on washing steps or limiting dilution. As a proof-of-principle, we screened human endothelial cells stimulated with vascular endothelial growth factor (VEGF) and constructed a peptide-based ligand-receptor map of the VEGF family. Next, we validated the motif PQPRPL as a novel chimeric ligand mimic that binds specifically to VEGF receptor-1 and to neuropilin-1. BRASIL may prove itself a superior method for probing target cell surfaces with a broad range of potential applications.

Monocyte-fibronectin interactions, via alpha(5)beta(1) integrin, induce expression of CXC chemokine-dependent angiogenic activity

Monocyte-derived macrophages are important sources of angiogenic factors in cancer and other disease states. Upon extravasation from vasculature, monocytes encounter the extracellular matrix. We hypothesized that interaction with extracellular matrix proteins leads monocytes to adopt an angiogenic phenotype. We performed endothelial cell chemotaxis assays on conditioned medium (CM) from monocytes that had been cultured in vitro on various matrix substrates (collagen I, laminin, Matrigel, fibronectin), in the presence of autologous serum, or on tissue culture plastic alone. Monocytes cultured on Matrigel and on fibronectin were the most potent inducers of angiogenic activity compared with tissue culture plastic or autologous serum-differentiated monocytes. This increased angiogenic activity was associated with increased expression of angiogenic CXC chemokines (IL-8, epithelial neutrophil-activating peptide-78, growth-related oncogene alpha, and growth-related oncogene gamma) but not of vascular endothelial growth factor. Additionally, CM from monocytes cultured on fibronectin-depleted Matrigel (MG(FN-)) induced significantly less angiogenic activity than CM from monocytes cultured on control-depleted Matrigel. ELISA analysis of CM from monocytes cultured on MG(FN-) revealed a significant decrease in GRO-alpha and GRO-gamma compared with CM from monocytes cultured on MG. Incubation of monocytes before adherence on fibronectin with PHSCN (a competitive peptide inhibitor of the PHSRN sequence of fibronectin binding via alpha(5)beta(1) integrin) results in diminished expression of angiogenic activity and CXC chemokines compared with control peptide. These data suggest that fibronectin, via alpha(5)beta(1) integrin, promotes CXC chemokine-dependent angiogenic activity from monocytes.

Ossification in the human calcaneus: a model for spatial bone development and ossification

Perichondral bone, the circumferential grooves of Ranvier and cartilage canals are features of endochondral bone development. Cartilage canals containing connective tissue and blood vessels are found in the epiphysis of long bones and in cartilaginous anlagen of small and irregular bones. The pattern of cartilage canals seems to be integral to bone development and ossification. The canals may be concerned with the nourishment of large masses of cartilage, but neither their role in the formation of ossification centres nor their interaction with the circumferential grooves of Ranvier has been established. The relationships between cartilage canals, perichondral bone and the ossification centre were studied in the calcaneus of 9 to 38-wk-old human fetuses, by use of epoxy resin embedding, three-dimensional computer reconstructions and immunhistochemistry on paraffin sections. We found that cartilage canals are regularly arranged in shells surrounding the ossification centre. Whereas most of the shell canals might be involved in the nourishment of the cartilage, the inner shell is directly connected with the perichondral ossification groove of Ranvier and with large vessels from outside. In this way the inner shell canal imports extracellular matrix, cells and vessels into the cartilage. With the so-called communicating canals it is also connected to the endochondral ossification centre to which it delivers extracellular matrix, cells and vessels. The communicating canals can be considered as inverted 'internal' ossification grooves. They seem to be responsible for both build up intramembranous osteoid and for the direction of growth and thereby for orientation of the ossication centre.

Tissue factor increases in the aqueous humor of proliferative diabetic retinopathy

BACKGROUND

Tissue factor (TF) is a cellular initiator of the coagulation cascade and is upregulated by the major factors of diabetic angiopathy, TF might thus be one of the key molecules in diabetic retinopathy (DR).

PURPOSE

To measure TF in diabetic eyes and evaluate its possible role in DR.

METHODS

TF concentration in the aqueous humor of the eyes in 44 patients with diabetes and 35 age-matched control patients was evaluated by ELISA. The concentration of TF in aqueous humor (AH) was compared with the grade of DR. The concentration of TF in AH was also compared with duration of diabetes, renal function, and blood glucose control. The serum TF concentration in each group was also compared. The correlation between the serum TF and aqueous TF in each patient was analyzed. The effect of vascular endothelial growth factor (VEGF) on the TF activity of cultured bovine retinal endothelial cells was evaluated.

RESULTS

The mean TF concentration in AH was higher in patients with active proliferative DR (244.5 pg/ml) than in either those with non-proliferative DR (132.4 pg/ml, P<0.05) or the control patients (114.9 pg/ml, P<0.01). The serum TF concentration in active proliferative DR patients (348.3 pg/ml) was significantly higher than in either non-proliferative DR patients, (235.9 pg/ml, P<0.01) or in the controls (223.5 pg/ml, P<0.01). However, the TF concentration of AH was not significantly correlated to that of the serum in each patient. The TF concentration in AH closely correlated with the grade of DR and protein concentration. VEGF increased the biological activity of TF in vitro.

CONCLUSION

The origin of TF in AH, however, is still not clearly understood. Nonetheless, TF in AH directly reflects the severity of ocular diabetic change, and the present results indicate that TF indeed plays some role in the progression of DR.

The angiogenic response to skeletal injury is preserved in the elderly

Angiogenesis is essential for normal bone formation and repair. Avascularity characterizes aberrant fracture union in the elderly, while angiogenic mechanisms during cutaneous wound repair are attenuated in aged humans. We hypothesized that skeletal injury results in local (circulating) and systemic (fracture site) 'angiogenic' responses and that these reparative mechanisms are attenuated with advanced patient age. This prospective study examined peripheral blood and fracture hematoma from 32 patients, 16 under 40 years and 16 over the age of 75, undergoing emergent surgery for isolated fracture. The angiogenic cytokines vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) were assayed. Endothelial cell cultures were supplemented with patient plasma and fracture hematoma and angiogenesis determined in vitro by measuring cell proliferation and blood vessel tube formation. Angiogenesis was determined in vivo using a murine dorsal wound pocket model and quantification of new blood vessel formation after 7 days. We found that all injured patients, irrespective of age, have elevated plasma and fracture hematoma levels of VEGF and PDGF. These elevated cytokine concentrations translate into biologically significant angiogenic effects, in vitro and in vivo. These effects are primarily VEGF mediated and are not dependent on patient age. The biological activity of these growth factors does not diminish with advanced age. Thus skeletal injury does result in local and systemic angiogenic responses whereby angiogenic cytokine availability and activity is preserved in the aged suggesting alternative mechanisms for the development of avascularity in delayed and fracture non-union in the elderly.

Serum vascular endothelial growth factor in late rheumatoid arthritis

OBJECTIVES

To investigate the serum levels of VEGF in patients with rheumatoid arthritis of long duration.

METHODS

Serum VEGF levels were measured in 118 patients with long-standing rheumatoid arthritis according to the ACR criteria (mean duration 12 years). The disease activity score was evaluated by the method of van der Heijde et al.

RESULTS

Serum levels of VEGF in patients with RA were significantly higher than in healthy controls. VEGF levels showed no correlation with CRP, SAA amyloid protein, or the disease activity score.

CONCLUSIONS

Our findings suggest that, contrary to the results reported in patients with early onset RA, where VEGF appears to play an active part in joint inflammation, in long-standing RA elevated VEGF serum levels may be an independent marker although its significance remain to be established.

Angiogenesis and endometrial cancer

Angiogenesis occurs more frequently in endometrial carcinomas developing against a background of endometrial atrophy rather than carcinomas arising from a hyperplastic endometrium. In some studies, angiogenesis is associated with unfavourable histopathological features, but not in others. In all studies, however, increased angiogenesis is related to poor prognosis. Vascular endothelial growth factor (VEGF) is the major stimulus for endothelial cell proliferation in endometrial carcinomas and is, therefore, associated with high angiogenesis. VEGF expression at the invading tumour front is 4-10 times higher than in the inner tumour areas and is significantly associated with poor prognosis, particularly within stage I endometrial disease. However, since its stimulating effect on endothelial cells is basically dependent on the presence of VEGF receptors, i.e. the flk-1(KDR), the detection of a functionally intact angiogenic pathway VEGF/flk-1 (KDR) is a more reliable and, indeed, independent prognostic parameter. The other angiogenic factor, thymidine phosphorylase (TP), is related to the adverse histopathological variables of the non endometrioid carcinomas, high tumour grade, deep myometrial invasion and advanced stage of disease, at least at the invading tumour front, and its prognostic significance is, therefore, limited. Furthermore, it is not directly related with increased angiogenesis. However, the simultaneous expression of high VEGF / high TP activity at the invading tumour front emerged as the most potent angiogenic phenotype in endometrial carcinomas, indicating that the two molecules are co-operating. Furthermore, a high TP activity in the stromal cells is associated with a high density of activated macrophages which further promotes endometrial tumour angiogenesis.

Cyclical mechanical stretching increases the expression of vascular endothelial growth factor in rat vascular smooth muscle cells

BACKGROUND AND PURPOSE

Mechanical forces have profound effects on vascular smooth muscle cells (VSMCs). The mechanism by which mechanical stimuli regulate vascular endothelial growth factor (VEGF) expression and regulation has yet to be elucidated. We investigated the effect of cyclical mechanical stretching on regulation of the VEGF gene in VSMCs.

MATERIALS AND METHODS

Cultured rat VSMCs grown on a flexible membrane base were stretched by applying a vacuum at 60 cycles/minute. VEGF concentration in the cultured media was determined by enzyme-linked immunoassay. VEGF gene expression was determined by Western blot and Northern blot. The location of VEGF in the VSMC was studied immunohistochemically. Chimeric constructs of the VEGF promoter were deleted and the promoter activity was determined by luciferase activity.

RESULTS

VEGF concentration increased by 21 to 32% as early as 10 minutes after stretching and remained at this level for up to 12 hours. The concentration of VEGF reached a maximum of 2.8-fold over that in control cells by 2 hours after stretching and declined slightly thereafter. The amount of VEGF mRNA in stretched cells increased as early as 1 hour after stretching, reached a maximum of 3.2-fold over the amount in control cells by 2 hours, and remained at this level for up to 6 hours after stretching. Immunohistochemical study confirmed increased VEGF expression in VSMCs after stretching. Stretched cells transfected with a Sac-Nhe fragment showed only 46% of the luciferase activity of unstretched control cells. However, stretched cells transfected with chimeric plasmids containing a Spe-Nhe fragment showed 2.8-fold luciferase activity over that in control cells.

CONCLUSIONS

Cyclical mechanical stretching upregulates expression of the VEGF gene in VSMCs at the transcription level. The VEGF 5'-flanking region contains a negative stretch-response element located in the 0.4-kb Sac-Pst fragment and a positive stretch-response element located in the 0.6-kb Spe-Sac fragment.

Vascular endothelial growth factor production by isolated rat hepatocytes after cold ischemia-warm reoxygenation

Inflammatory disturbances in the liver microcirculation have been associated with preservation injury of hepatic grafts. Vascular endothelial growth factor (VEGF), a proinflammatory growth factor released by hepatocytes, acts on sinusoidal endothelial cells, but its implication in graft injury is still unclear. We studied VEGF production by rat hepatocytes after cold ischemia and warm reoxygenation and compared the capacity of University of Wisconsin (UW) and sodium-lactobionate-sucrose (SLS) preservation solutions to maintain this hepatocellular function. Isolated hepatocytes were kept for 0, 24, and 48 hours at 4 degrees C in either solution (cold ischemia), then incubated for 1 to 24 hours at 37 degrees C (warm reoxygenation). We assessed cell viability and production of VEGF messenger RNA (mRNA) and protein. Cell viability decreased in a linear time-dependent fashion by 10% after 48 hours of cold preservation and by an additional 40% after 24 hours of warm culture. Very little VEGF mRNA could be detected after up to 48 hours of simple cold preservation in either solution. However, subsequent warm culture led to a robust and rapid increase in VEGF mRNA expression within the first hour, which declined to close to background levels within 8 to 12 hours in culture. This effect was more important in cells preserved in SLS than UW solution. Similarly, cold preservation alone did not trigger VEGF secretion. VEGF secretion was detected after culturing hepatocytes at 37 degrees C and reached a maximal secretion rate within 12 to 15 hours. However, VEGF production by preserved cells was reduced compared with unstored cells. In conclusion, cold ischemia and warm reoxygenation triggers VEGF mRNA expression by hepatocytes, but subsequent VEGF secretion is partially impaired, suggesting posttranslational defects.

Gene therapy for cardiovascular disease: a case for cautious optimism

There is currently intense interest in the development of gene therapy for cardiovascular disease. The stimulation of therapeutic angiogenesis for ischemic heart disease has been one of the areas of greatest promise. Encouraging results have been obtained with the angiogenic cytokines vascular endothelial growth factor (VEGF) and basic fibroblast growth factor in animal models, leading to clinical trials in ischemic heart disease. VEGF also has therapeutic potential in a second area of cardiovascular gene therapy, the enhancement of arterioprotective endothelial functions to prevent postangioplasty restenosis and bypass graft arteriopathy. The endothelial cell growth and survival functions of VEGF promote endothelial regeneration, whereas VEGF-induced endothelial production of NO and prostacyclin inhibits vascular smooth muscle cell proliferation. Inhibition of neointimal hyperplasia may also be achieved by gene transfer of endothelial NO synthase (eNOS), PGI synthase, or cell cycle regulators (retinoblastoma, cyclin or cyclin-dependent kinase inhibitors, p53, growth arrest homeobox gene, fas ligand) or antisense oligonucleotides to c-myb, c-myc, proliferating cell nuclear antigen, and transcription factors such as nuclear factor kappaB and E2F. An improved understanding of etiologically complex pathologies involving the interplay of genes and the environment, such as atherosclerosis and systemic hypertension, has led to the identification of new targets for gene therapy, with the potential to alleviate inherited genetic defects such as familial hypercholesterolemia. The use of vasodilator gene overexpression and antisense knockdown of vasoconstrictors to reduce blood pressure in animal models of systemic and pulmonary hypertension offers the prospect of gene therapy for human hypertensive disease. The renin-angiotensin system has been the target of choice for antihypertensive strategies because of its wide distribution and additional effects on fibrinolytic and oxidative stress pathways. Gene therapy in cardiovascular disease has an exciting future but remains at an early stage. Further developments in gene transfer vector technology and the identification of additional target genes will be required before its full therapeutic potential can be realized.

Expression of cyclooxygenase-2 in ovarian mature cystic teratomas with malignant transformation

Cyclooxygenase-2 (COX-2) has been reported to be associated with tumor progression and angiogenesis and we previously reported that an increase in COX-2 expression might be associated with malignant transformation and tumorigenesis of epithelial ovarian neoplasms. In this study, COX-2 expression of ovarian mature cystic teratomas with malignant transformation, a rare entity accounting for just 1.8% of all mature cystic teratomas, was investigated using immunohistochemical techniques. There were 89 cases of mature cystic teratomas treated with surgery as their initial therapy at Osaka City University Medical School Hospital between 1995 and 2001. Ten cases of these were selected for study; five cases of mature cystic teratoma with malignant transformation, and five cases of mature benign teratoma. Expressions of CD34, vascular endothelial growth factor (VEGF), and COX-2 were investigated. Expressions of VEGF and COX-2 were strong in tissues of mature cystic teratomas with squamous cell carcinoma; however, expressions of them were hardly apparent in mature benign teratomas and in mature cystic teratomas with adenocarcinomas. These results tend to suggest that COX-2 is associated with tumor growth and progression in mature cystic teratomas with squamous cell carcinoma, as opposed to mature benign teratomas and mature cystic teratomas with adenocarcinomas.

Clinical significance of urinary vascular endothelial growth factor in patients with superficial bladder tumors

Vascular endothelial growth factor (VEGF) is an important mediator of tumor angiogenesis and has been shown to be excreted in the urine of bladder cancer patient. The goal of this study was to evaluate urinary VEGF levels of patients with superficial bladder transitional cell carcinoma (TCC) and to determine its predictive value for recurrence. Pre-operative urinary VEGF levels were determined in 31 patients with superficial bladder TCC and 10 control patients. A quantitative enzyme immunoassay was used to measure urinary VEGF levels and the urine VEGF concentration was corrected by the creatinine concentration in a 24-h urine specimen. The corrected urinary VEGF levels were higher in patients than controls (p=0.003). Ten of 31 patients had TCC recurrences during this study. Corrected urinary VEGF levels were significantly higher in recurrent vs. non-recurrent patients (p=0.001). A cut-off value of 0.32 (corrected urinary VEGF levels) was valuable for predicting recurrences in this prospective study. However, there was no statistical correlation between VEGF levels and tumor stage (Ta or T1), tumor size or tumor grade. Pre-operative urinary VEGF levels are associated with a risk of recurrence in patient with superficial bladder TCC. Quantification of urinary VEGF may prove to be a valuable, non-invasive indicator of carcinoma recurrence in patients with superficial bladder TCC. Urinary VEGF may be a therapeutic target for intravesical therapy. However, because of the small number of cases, further studies with larger number of patients will be needed to clarify this issue.

Clinical applications of cardiovascular angiogenesis

Angiogenesis is fundamental to both normal physiologic (wound healing) and pathologic (cancer) processes. Manipulation of divergent angiogenic signals promises effective therapy of atherosclerotic cardiovascular disease. Positive proangiogenic strategies promise collateral circulation to ischemic territories, while negative antiangiogenic strategies starve the fibromuscular proliferation within the atherosclerotic lesion. Indeed, recent phase 1 trials suggest that delivering DNA or recombinant protein to the site of vascular occlusion may stimulate physiologically significant collateral circulation in chronically ischemic myocardium. While symptomatic and functional improvement has been documented, toxicity profiles and effects on long-term patient survival are still unclear. The purposes of this article are as follows: (1) to review the pathophysiologic basis for pro- and antiangiogenic strategies in the treatment of cardiovascular disease, (2) to examine the clinical trials of proangiogenic gene or recombinant protein delivery into ischemic beds, and conversely, (3) to explore antiangiogenic strategies in the prevention and treatment of intimal neovascularization and smooth muscle proliferation within the vessel wall.

Endothelial survival factors as targets for antineoplastic therapy

Angiogenesis is essential for the growth and metastasis of solid tumors. The angiogenic process includes not only development of new blood vessels but also maintenance of the existing vasculature. Recent studies have demonstrated that several factors induce angiogenesis and also function as endothelial cell survival factors. Vascular endothelial growth factor, a potent angiogenic factor, is an endothelial cell survival factor whose tyrosine kinase receptors are limited to endothelial cells. Members of the angiopoietin family also bind to an endothelial cell-specific tyrosine kinase receptor. Angiopoietin-1 has been shown to stabilize endothelial cell networks, whereas angiopoietin-2 is antagonistic to angiopoietin-1 and destabilizes endothelial cell networks. Pericytes contribute to endothelial cell stabilization by cell-cell contact, secretion of survival factors, or both. In addition, integrins may function as endothelial cell survival factors by numerous mechanisms after binding to the extracellular matrix. The effects of many endothelial cell survival factors act in concert with vascular endothelial growth factor to enhance this essential step in angiogenesis. Targeting any of the aforementioned mechanisms for endothelial cell survival may provide novel therapeutic antineoplastic strategies.

Neurogenic perspective on vascular endothelial growth factor: review of the literature

Among a variety of approaches used to stimulate nerve regeneration in experimental settings, is the use of a class of proteins designated as nerve growth factors and various other growth factors. Of these, vascular endothelial growth factor (VEGF), has been demonstrated to possess a potential to stimulate nerve regeneration in addition to its angiogenic properties. A number of studies have investigated the role of VEGF in nerve regeneration, demonstrating that it has both neurogenic and mitogenic activity on cells in the peripheral nervous system. It is therefore likely that VEGF is a molecule of major significance for nerve homeostasis, especially during development, and possibly after nerve injury. This paper reviews the mechanisms of VEGF signal transduction in neurogenesis, and focuses on recent studies that have considerably widened the understanding of the way in which VEGF affects peripheral nerve regeneration. By emphasizing the possible therapeutic implication of VEGF in nerve pathology, the authors would like to introduce a new research approach to study the role of VEGF in the nervous system. They believe that in the future, the factor might become a powerful tool in enhancing nerve regeneration in clinical practice.

Angiogenesis, vascular endothelial growth factor and platelet-derived growth factor-BB expression, iron deposition, and oxidation-specific epitopes in stented human coronary arteries

Pathogenesis of in-stent restenosis remains poorly understood because information from human histopathologic studies is scarce. We used an improved saw-grinding and cutting method on methacrylate-embedded samples containing metal stents, which allows in situ hybridization and immunohistochemical analysis of in-stent restenosis. Twenty-one samples were collected 3 hours to 3 years after stenting from 6 patients aged 36 to 81 years. Except in very early samples collected within hours after the stent deployment, neovascularization was present in all segments studied. At advanced stages, extensive neovascularization was located mainly at the luminal side of the stent struts and was only rarely accompanied by inflammatory cells. The neovessels colocalized with vascular endothelial growth factor (VEGF)-A mRNA and protein expression as well as with iron deposits and oxidation-specific epitopes, which imply the presence of chronic oxidative stress. VEGF-A expression was detected in the same areas containing macrophages, endothelial cells, and, to a lesser extent, smooth muscle cells, which also showed platelet-derived growth factor-BB expression. We conclude that in-stent restenosis features neovascularization, VEGF-A and platelet-derived growth factor-BB expression, and iron deposition, which is most probably derived from microhemorrhages. These mechanisms may play an important role in the development of neointimal thickening and could provide useful targets for the prevention and treatment of in-stent restenosis.

Intracoronary administration of recombinant human vascular endothelial growth factor to patients with coronary artery disease

BACKGROUND

Patients with severe myocardial ischemia who are not candidates for percutaneous or surgical revascularization have few therapeutic options. Therapeutic angiogenesis in animal models with use of recombinant human vascular endothelial growth factor (rhVEGF) has resulted in successful revascularization of ischemic myocardium. This was a dose escalation trial designed to determine the safety and tolerability of intracoronary rhVEGF infusions.

METHODS AND RESULTS

Patients were eligible if they had stable exertional angina, a significant reversible perfusion defect by stress myocardial perfusion study, and coronary anatomy that was suboptimal for percutaneous coronary intervention or coronary artery bypass grafting. rhVEGF was administered to a total of 15 patients by 2 sequential (eg, right and left) intracoronary infusions, each for 10 minutes, at rates of 0.005 (n = 4), 0.017 (n = 4), 0.050 (n = 4), and 0.167 mg/kg/min (n = 3). Pharmacokinetic sampling and hemodynamic monitoring were performed for 24 hours. Radionuclide myocardial perfusion imaging was performed before treatment and at 30 and 60 days after treatment. Follow-up angiograms were performed on selected patients at 60 days. The maximally tolerated intracardiac dose of rhVEGF was 0.050 mg/kg/min. Minimal hemodynamic changes were seen at 0.0050 mg/kg/min (2% +/- 7% [SD] mean decrease in systolic blood pressure from baseline to nadir systolic blood pressure), whereas at 0.167 mg/kg/min there was a 28% +/- 7% mean decrease from baseline to nadir (136 to 95 mm Hg systolic). Myocardial perfusion imaging was improved in 7 of 14 patients at 60 days. All 7 patients with follow-up angiograms had improvements in the collateral density score.

CONCLUSION

rhVEGF appears well tolerated by coronary infusion at rates up to 0.050 mg/kg/min. This study provides the basis for future clinical trials to assess the clinical benefit of therapeutic angiogenesis with rhVEGF.

Vascular endothelial growth factor: its prognostic, predictive, and therapeutic implications

Since the discovery that cancer development requires the growth of new blood vessels, many investigations have revealed the key molecules in the regulation of new vessel formation. One of the most important of these molecules is vascular endothelial growth factor (VEGF)--an endothelial-cell-specific mitogen and survival factor. VEGF also causes increased vascular permeability and recruits progenitor endothelial cells from the bone marrow. Clinical observations have confirmed that VEGF status is closely associated with the extent of neovascularisation and prognosis in many solid tumours. VEGF status is predictive of resistance to various treatments, including radiotherapy, chemotherapy, and endocrine therapy. Preliminary results also indicate that anti-VEGF treatment suppresses cancer progression without serious toxic effects. Various approaches for the control of cancers involving inhibition of the activity of VEGF are currently being investigated. This review considers the clinical implications of VEGF, particularly its prognostic, predictive, and therapeutic value.