Vascular Endothelial Growth Factor Antagonist Research Articles

Destruction of tumor vasculature and abated tumor growth upon VEGF blockade is driven by proapoptotic protein Bim in endothelial cells

For malignant growth, solid cancers must stimulate the formation of new blood vessels by producing vascular endothelial growth factor (VEGF-A), which is required for the survival of tumor-associated vessels. Novel anticancer agents that block VEGF-A signaling trigger endothelial cell (EC) apoptosis and vascular regression preferentially within tumors, but how the ECs die is not understood. In this study, we demonstrate that VEGF-A deprivation, provoked either by drug-induced tumor shrinkage or direct VEGF-A blockade, up-regulates the proapoptotic BH3 (Bcl-2 homology 3)-only Bcl-2 family member Bim in ECs. Importantly, the tumor growth inhibitory activity of a VEGF-A antagonist required Bim-induced apoptosis of ECs. These findings thus reveal the mechanism by which VEGF-A blockade induces EC apoptosis and impairs tumor growth. They also indicate that drugs mimicking BH3-only proteins may be exploited to kill tumor cells not only directly but also indirectly by ablating the tumor vasculature.

A Phase 2/3, Multicenter, Randomized, Double-Masked, 2-Year Trial of Pegaptanib Sodium for the Treatment of Diabetic Macular Edema

To confirm the safety and compare the efficacy of intravitreal pegaptanib sodium 0.3 mg versus sham injections in subjects with diabetic macular edema (DME) involving the center of the macula associated with vision loss not due to ischemia. Randomized (1:1), sham-controlled, multicenter, parallel-group trial. Subjects with DME. Subjects received pegaptanib 0.3 mg or sham injections every 6 weeks in year 1 (total = 9 injections) and could receive focal/grid photocoagulation beginning at week 18. During year 2, subjects received injections as often as every 6 weeks per prespecified criteria. The primary efficacy endpoint was the proportion gaining ≥ 10 letters of visual acuity (VA) from baseline to year 1. Safety was monitored throughout. In all, 260 (pegaptanib, n = 133; sham, n = 127) and 207 (pegaptanib, n = 107; sham, n = 100) subjects were included in years 1 and 2 intent-to-treat analyses, respectively. A total of 49 of the 133 (36.8%) subjects from the pegaptanib group and 25 of the 127 (19.7%) from the sham group experienced a VA improvement of ≥ 10 letters at week 54 compared with baseline (odds ratio [OR], 2.38; 95% confidence interval, 1.32-4.30; P = 0.0047). For pegaptanib-treated subjects, change in mean VA from baseline by visit was superior (P<0.05) to sham at weeks 6, 24, 30, 36, 42, 54, 78, 84, 90, 96, and 102. At week 102, pegaptanib-treated subjects gained, on average, 6.1 letters versus 1.3 letters for sham (P<0.01). Fewer pegaptanib- than sham-treated subjects received focal/grid laser treatment (week 54, 31/133 [23.3%] vs 53/127 [41.7%], respectively, P = 0.002; week 102, 27/107 [25.2%] vs 45/100 [45.0%], respectively, P = 0.003). The pegaptanib treatment group showed significantly better results on the National Eye Institute-Visual Functioning Questionnaire than sham for subscales important in this population. Pegaptanib was well tolerated; the frequencies of discontinuations, adverse events, treatment-related adverse events, and serious adverse events were comparable in the pegaptanib and sham groups. Patients with DME derive clinical benefit from treatment with the selective vascular endothelial growth factor antagonist pegaptanib 0.3 mg. These findings indicate that intravitreal pegaptanib is effective in the treatment of DME and, taken together with prior study data, support a positive safety profile in this population. Proprietary or commercial disclosure may be found after the references.

The influence of bevacizumab on human choroidal melanoma in vivo

Objective To investigate the influence of vascular endothelial growth factor (VEGF)antagonist bevacizumab on the growth of human choroidal melanoma (CM) OCM-1 cell xenografts in nude mice, and to explore the probable mechanism. Methods OCM-1 cells were subcutaneously implanted on 18 nude mice to establish ectopic model of human CM. The nude mice with the tumor of 5 mm in diameter were randomly divided into three groups: untreated group (group A), normal saline (NS) group (group B), drug treated group (group C). Bevacizumab was intraperitoneally injected for 14 consecutive days in group C, and the same volume of NS was used at a same way in group B. The volume and weight of implanted tumor as well as inhibitory rates of drug on tumor were calculated, ki67 and survivin proteins were measured with immunohistochemistry, and the mRNA expression of VEGF and survivin were assessed by RT-PCR. Results The volume and weight of tumor was (598.86±321.81) mm3 , (0. 66±0. 15) g;(1 715. 15±278. 16)mm3 , (1.54±0. 39) g and (1 750. 23±206.36) mm3 , (1. 54±0. 31) g in groups C, A and B, respectively.There were significant differences between group C and A (F=34.53, P=0. 00) and group C and group B(F= 8.69, P=0.01). The inhibitory rate of these three groups were 57. 14%, 5. 31%, 6. 25%,respectively, and the proliferation index (PI) of ki67 in these three groups were (51.85±1.32)%, (46. 30±1.39) %, (27. 90±0. 90)%, respectively, there were significant differences in ki67 PI between C group and A or B group ( H = 15.17, P = 0.00). The expression of survivin mRNA was (0.49 ± 0.02 ), (0. 82 ± 0. 05)and (0. 61±0.05) in groupss C, A and B, respectively, there were significant differences between C group and A or B group (F=15.17, P＜0. 05) . The expression of VEGF mRNA was (0. 32±0. 08), (0. 73±0. 07), (0. 80±0.04) in groups C, A and B, significant difference was found between group C and A or B group (F= 12.05,P＜0. 05). Conclusion Bevacizumab can inhibit the growth of human CM in nude mice probably by inhibiting the activity of VEGF and downregulating survivin expression of the tumor as well as inhibiting the growth of the tumor. Key words: Choroid neoplasms; Antibodies, monoclonal; Vascular endothelial growth factors; Cell proliferation/drug effects; Apoptosis

Complexity of tumor vasculature and molecular targeting therapies

Malignant solid tumors require blood supply for their uncontrollable progression. Angiogenic blood vessels generally sprout from preexisting vascular cells. In addition, various types of precursor cells also participate in tumor neovascularization. They include endothelial progenitor cells, hematopoietic stem cells and mesenchymal stem cells that are stimulated and attracted into tumor lesion, in which a wide variety of proinflammatory factors are involved. Among key molecules, vascular endothelial growth factor (VEGF) works as a mastermind regulator. Humanized monoclonal antibodies targeting VEGF-mediated signaling pathways are currently used as the most pervasive drugs in several types of progressive tumors. Adverse effects of these drugs include hypertension and proteinuria. Such symptoms are widely observed in preeclamptic patients whose blood contain high amount of natural VEGF antagonist. Vasoactive G protein-coupled receptors (GPCRs)-mediated signalings such as renin-angiotensin system and chemokine axes are also noticed that they may become effective therapeutic targets. In this review, we discuss general view of angiogenic microenvironment in solid tumors, and highlight several key signaling molecules and inhibitory effects of them on the whole system.

Effect of VEGF and VEGF Trap on vascular endothelial cell signaling in tumors

Vascular endothelial growth factor (VEGF) A is a major promoter of tumor angiogenesis and a prime target of antiangiogenic cancer therapy. To examine whether endothelial cell signaling might provide histological biomarkers of angiogenesis and VEGF activity in vivo, normal mouse organs and multiple tumor models were studied immunohistochemically for endothelial expression of activated ERK, STAT3, and AKT. Phospho(p)-ERK and p-STAT3 expression was negligible in the endothelia of normal organs but was significantly elevated in tumor endothelium. p-AKT was present at significant and comparable levels in both tumor and normal endothelia. In K1735 tumors induced to express more VEGF, endothelial p-ERK, p-STAT3 and p-AKT increased accompanied by signs of accelerated angiogenesis. Treatment of K1735 and Colo-205 tumors with the VEGF inhibitor, VEGF Trap (aflibercept), decreased tumor endothelial p-ERK, p-STAT3 and p-AKT expression accompanied by signs of antiangiogenic effect. These results show that endothelial p-ERK and p-STAT3 (but not p-AKT) distinguish tumor from normal vessels and that the presence of these two signaling intermediates may be useful indicators of tumor angiogenic activity and angiogenesis inhibition by VEGF antagonist

P120 Profile of pregnant Brazilian patients in a glomerulopathies outpatient clinic

Ruptured human anterior cruciate ligaments (ACL) contain vascular stem cells capable of enhancing the healing of tendon grafts. In the current study we explored the role that neo-angiogenesis plays in ACL healing. ACL-derived CD34+ cells were isolated via Fluorescence Activated Cell Sorting (FACS) from the rupture sites of human ACLs. The cells were then virally transduced to express either vascular endothelial growth factor (VEGF) or soluble FLT-1 (sFLT-1), which is an antagonist of VEGF. We established five groups: CD34+VEGF(100%), where 100% of the cells were transduced with VEGF, CD34+VEGF(25%), where only 25% of the cells were transduced with VEGF, CD34+, CD34+sFLT-1, and a No cells group. The CD34+sFLT1 group had a significant reduction in biomechanical strength compared to the CD34+ group at 4 and 8 weeks; whereas the biomechanical strength of the CD34+VEGF(25%) group was significantly greater than the CD34+ group at week 4; however, no difference was observed by week 8. Immunohistochemical staining demonstrated a significantly lower number of isolectin B4 and hCD31 positive cells, markers associated with angiogenesis, in the CD34+sFLT1 group, and a higher number of isolectin B4 and hCD31 positive cells in the CD34+VEGF(100%) and CD34+VEGF(25%) groups compared to the CD34+ group. Graft maturation was significantly delayed in the CD34+sFLT1 group and accelerated in the CD34+VEGF(25%) group compared to the CD34+ group. In conclusion, blocking VEGF reduced angiogenesis, graft maturation and biomechanical strength following ACL reconstruction. Native expression of VEGF by the CD34+ cells improved tendon graft maturation and biomechanical strength; however, over-expression of VEGF impeded improvements in biomechanical strength.

Liver Resection Remains a Safe Procedure After Neoadjuvant Chemotherapy Including Bevacizumab

This study was conducted to analyze if the combination of Bevacizumab with standard chemotherapy increases postoperative morbidity and mortality after resection of colorectal liver metastases as compared with resection after chemotherapy alone. Parameters contributing to an increased morbidity were evaluated. Most patients referred for colorectal liver metastases are treated with neoadjuvant chemotherapy before hepatic surgery. Targeted agents like the vascular endothelial growth factor-antagonist Bevacizumab are increasingly added to standard therapy to prolong survival; however, little is known about the consequences of this policy in the perioperative period. One hundred-two patients treated between 2005 and 2009, who received neoadjuvant chemotherapy combined with Bevacizumab (CHT + B) were identified. A cohort of 112 patients treated without chemotherapy alone before resection served as the control group (CHT). Complications were graded within an established staging system and the therapeutic consequences were laid down. Uni- and multivariate analysis of factors contributing to postoperative complications in the CHT + B group was performed using a logistic regression model. Postoperative complications occurred in 45 (44%, CHT + B) and 38 (34%, CHT) patients, respectively (P = 0.216). The incidence of severe complications requiring surgical or radiologic intervention or leading to organ failure was 10.8% in the CHT + B group and 7.1% in the CHT group (P = 0.350). Increased age, low serum albumin, resection of more than 3 liver segments and synchronous bowel procedures requiring an anastomosis were associated with an increased morbidity rate in the multivariate regression analysis. No patient died in either group. The addition of Bevacizumab to standard chemotherapy before resection of colorectal liver metastases does not seem to increase postoperative morbidity. Caution should be given to extended resections >3 liver segments and synchronous bowel anastomoses.

Vascular endothelial growth factor antagonism inhibits breast cancer proliferation via Akt and Erk signaling

While recent epidemiological studies report preeclampsia has long‐term protective effects against breast cancer, the mechanisms and the factors responsible for these observations remain unknown. We have previously shown that proliferation of breast cancer cells in vitro is decreased when treated with serum from rats with placenta ischemia‐induced model of preeclampsia. We hypothesize that anti‐angiogenic factors elaborated by the ischemic placenta such as soluble fms‐like tyrosine kinase‐1 (sFlt‐1), a vascular endothelial growth factor antagonist, inhibits proliferation of breast cancer cells by reducing Erk 1/2 and Akt signaling. To this end, we treated MCF‐7 and LCC9 breast cancer cells with 15 ng/mL sFlt1 for up to 24 hrs and measured proliferation and Akt and Erk signaling. sFlt‐1 reduced MCF‐7 (66.8% ‐ 24h) and LCC9 (98.8% ‐ 24h) proliferation, and decreased Akt activation 44.9% within 5 minutes of treatment and 73.0% 24 hours post‐treatment. Erk1/2 phosphorylation was reduced by 92.6% after 30 minutes of treatment and by 24 hours Erk1/2 activation was minimal in both the control and treated cells. Taken together sFlt‐1 may act on key regulators of cell survival and proliferation at early time points to regulate breast cancer cell proliferation and survival. Understanding the mechanisms responsible for these observations may reveal novel therapeutic approaches to cancer prevention and treatment.

Vascular Endothelial Growth Factor Secreted by Activated Stroma Enhances Angiogenesis and Hormone-Independent Growth of Estrogen Receptor–Positive Breast Cancer

"Reactive" or activated stroma characterizes many malignancies including breast cancers. Recently, we isolated a reactive mouse mammary gland stromal cell line called BJ3Z. These cells express alpha-smooth muscle actin and stromal cell-derived factor 1 (SDF-1) and are tumorigenic when injected into mice. Here we show that, in vivo, BJ3Z cells influence the angiogenesis and proliferation of xenografted estrogen receptor (ER)-positive MCF-7 human breast cancer cell-derived solid tumors. The growth-promoting effects of BJ3Z cells are equivalent to those of estradiol (E(2)). BJ3Z cells also increase the proliferation of normal mouse mammary luminal cells adjacent to tumors. In vitro, BJ3Z cells reorganize and increase the proliferation of cocultured malignant MCF-7 and normal human breast MCF10A cells grown as organoids in three-dimensional culture. The effects of BJ3Z cells on MCF-7 cells are equivalent to those of E(2). In contrast, BJ3Z cells do not alter the growth of highly aggressive ER-negative MDA-MB-231 human breast cancer cells. We show that BJ3Z cells secrete vascular endothelial growth factor (VEGF). The growth of MCF-7 organoids induced by BJ3Z can be inhibited by antagonists of VEGF and SDF-1. Conversely, recombinant VEGF stimulates the proliferation of MCF-7, but not MDA-MB-231, organoids. We conclude that, in addition to angiogenesis, VEGF released by activated stroma increases the growth of ER-positive malignant epithelial cells and of adjacent normal epithelium. Because activated stroma can substitute for E(2) and fosters hormone-independent growth of ER-positive tumors, we suggest that breast cancers exhibiting intrinsic hormone resistance may respond to antiangiogenic therapies.

Prolonged blockade of VEGF receptors does not damage retinal photoreceptors or ganglion cells

It has recently been reported that relatively short-term inhibition of vascular endothelial growth factor (VEGF) signaling can cause photoreceptor cell death, a potentially clinically important finding since VEGF blockade has become an important modality of treatment of ocular neovascularization and macular edema. However, in a set of studies in which we achieved extended and complete blockage of VEGF-induced vascular leakage through retinal expression of a VEGF binding protein, we did not observe any toxicity to retinal neurons. To follow-up on these apparently discrepant findings, we designed a set of experiments with the kinase inhibitor SU4312, which blocks phosphorylation of VEGF receptors, to look directly for evidence of VEGF inhibition-related retinal toxicity. Using transgenic mice with sustained expression of VEGF in photoreceptors, we determined that periocular injection of 3 microg of SU4312 every 5 days markedly suppressed subretinal neovascularization, indicating effective blockade of VEGF signaling. Wild-type mice given periocular injections of 5 microg of SU4312 every 5 days for up to 12 weeks showed normal scotopic and photopic electroretinograms (ERGs), no TUNEL stained cells in the retina, and no reduction in outer nuclear layer thickness. Incubation of cultured ganglion cells or retinal cultures containing photoreceptors with high doses of SU4312 did not reduce cell viability. These data suggest that blocking VEGF signaling in the retina for up to 12 weeks does not damage photoreceptors nor alter ERG function and should reassure patients who are receiving frequent injections of VEGF antagonists for choroidal and retinal vascular diseases.

Use of pegaptanib for recurrent and non-clearing vitreous haemorrhage in proliferative diabetic retinopathy

Diabetes is the leading cause of blindness in the United Kingdom among people of working age. Many with proliferative diabetic retinopathy (PDR) go on to develop vitreous haemorrhage (VH). Those with recurrent or non-clearing VH require vitrectomy to restore vision. Pegaptanib is a vascular endothelial growth factor antagonist that disrupts the proliferative cascade and has been shown to precipitate regression of retinal neovascularisation. We assessed the effect of pre-operative intravitreal (IVT) pegaptanib on the timing, difficulty, and outcome of vitrectomy for recurrent VH in PDR. Fourteen consecutive patients (15 eyes) were given a course of 1-3 IVT pegaptanib injections and vitrectomy was performed when indicated by the recurrence or persistence of VH, or progression of associated tractional retinal detachment (TRD). The range of patient follow-up was from 6 months to 2 years. All had no further VH for at least 4 weeks after IVT pegaptanib. Five eyes remained free from VH until the end of the study (8-25 months), thus obviating the need for vitrectomy. Two further cases avoided vitrectomy following further IVT pegaptanib. In the majority of patients with VH, IVT pegaptanib created a window for further laser and risk factor optimisation. Surgery was faster and less challenging, compared with conventional vitrectomy for recurrent VH due to PDR. IVT pegaptanib can be considered in diabetic patients with VH. Approximately one-third may avoid vitrectomy altogether. There are clear intra-operative advantages of using IVT pegaptanib pre-operatively. However, caution should be exercised where there is pre-existing TRD.

Vascular Endothelial Growth Factor: Much More than an Angiogenesis Factor

Vascular endothelial growth factor (VEGF) is best known as a cytokine essential for embryonic vasculogenesis and for the angiogenesis associated with various pathologies including cancer. However, VEGF also serves other functions that are less widely recognized. An early study (Berse et al., 1992) revealed widespread expression of VEGF transcripts in adult tissues devoid of ongoing neovascularization, thereby predicting additional VEGF functions distinct from angiogenesis. More recent studies have confirmed that VEGF does indeed serve multiple additional functions, including normal maintenance of endothelial and neural cell compartments. These findings have important implications for the use of VEGF antagonists and VEGF receptor antagonists in patients for which inhibition of pathological angiogenesis is the therapeutic goal.

Anti-VEGF Therapies and Blood Pressure: More Than Meets the Eye

"Wet" (also called neovascular) age-related macular degeneration (AMD) is a chronic progressive disease characterized by leakage of fluid or blood from choroidal neovascularization. It remains the leading cause of blindness in the developed world. Vascular endothelial growth factor (VEGF), which plays a key role in the pathogenesis of retinal neovascularization and vessel leakage leading to central vision loss, has emerged as a potential target in the treatment of wet AMD. Importantly, large-scale clinical trials have demonstrated that intravitreal VEGF antagonism prevents vision loss and may even improve visual acuity in patients with neovascular AMD. Because VEGF and its downstream mediator nitric oxide have a well-established cardioprotective role, however, it can be argued that the beneficial effects of VEGF antagonism in the eye may come at the cost of adverse systemic effects, particularly myocardial infarction and stroke.

Estrogen and selective estrogen receptor modulators regulate vascular endothelial growth factor and soluble vascular endothelial growth factor receptor 1 in human endometrial stromal cells

To determine whether 17beta-estradiol (E(2)) and selective estrogen receptor modulators can regulate vascular endothelial growth factor (VEGF) and soluble VEGF receptor 1 (sVEGFR-1) as a VEGF antagonist in human endometrial stromal cells (ESCs). In vitro experiment. Research laboratory at Kansai Medical University. Sixteen patients undergoing hysterectomy for benign reasons. The ESCs were cultured with E(2), 4-hydroxytamoxifen (OHT), and raloxifene. The VEGF and sVEGFR-1 messenger RNA (mRNA) levels in ESCs were determined using quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Free (unbound) VEGF and sVEGFR-1 protein levels from ESCs were measured using ELISA kits. The E(2) significantly induced VEGF mRNA levels, whereas E2 caused a significant decrease in sVEGFR-1 messenger RNA (mRNA) levels. The E(2) or OHT significantly increased the VEGF production levels and attenuated the sVEGFR-1 production compared with control, but raloxifene had no significant effect. The decrease in levels of free VEGF was proportional to the increase in sVEGFR-1 levels in the culture media of ESCs. The E(2) or OHT stimulates VEGF production and concurrently attenuates sVEGFR-1 production in ESCs. This consequential increase in VEGF:sVEGFR-1 ratio might enhance the biological effects of VEGF on the angiogenic environment in human endometrium.

Human inflammatory synovial fibroblasts induce enhanced myeloid cell recruitment and angiogenesis through a hypoxia‐inducible transcription factor 1α/vascular endothelial growth factor–mediated pathway in immunodeficient mice

Hyperplasia and phenotypic changes in fibroblasts are often observed in chronic inflammatory lesions, and yet the autonomous pathogenic contribution of these changes is uncertain. The purpose of this study was to analyze the intrinsic ability of fibroblasts from chronically inflamed synovial tissue to drive cell recruitment and angiogenesis. Fibroblasts from patients with rheumatoid arthritis (RA) or osteoarthritis (OA), as well as fibroblasts from healthy synovial tissue and healthy skin, were cultured and subcutaneously engrafted into immunodeficient mice. Cell infiltration and angiogenesis were analyzed in the grafts by immunohistochemical studies. The role of vascular endothelial growth factor (VEGF), CXCL12, and hypoxia-inducible transcription factor 1alpha (HIF-1alpha) in these processes was investigated using specific antagonists or small interfering RNA (siRNA)-mediated down-regulation of HIF-1alpha in fibroblasts. Inflammatory (OA and RA) synovial fibroblasts, compared with healthy dermal or synovial tissue fibroblasts, induced a significant enhancement in myeloid cell infiltration and angiogenesis in immunodeficient mice. These activities were associated with increased constitutive and hypoxia-induced expression of VEGF, but not CXCL12, in inflammatory fibroblasts compared with healthy fibroblasts. VEGF and CXCL12 antagonists significantly reduced myeloid cell infiltration and angiogenesis. Furthermore, targeting of HIF-1alpha expression by siRNA or of HIF-1alpha transcriptional activity by the small molecule chetomin in RA fibroblasts significantly reduced both responses. These results demonstrate that chronic synovial inflammation is associated with stable fibroblast changes that, under hypoxic conditions, are sufficient to induce inflammatory cell recruitment and angiogenesis, both of which are processes relevant to the perpetuation of chronic inflammation.

Different properties of VEGF-antagonists: Bevacizumab but not Ranibizumab accumulates in RPE cells

Vascular endothelial growth factor (VEGF) antagonists are currently the therapy of choice for age-related macular degeneration. Here we compared the effects of FDA-approved Ranibizumab and off-label used Bevacizumab on RPE cells, investigating their respective uptake by RPE cells over time. Primary porcine RPE cells were treated with Bevacizumab or Ranibizumab, respectively. Uptake of the respective VEGF-antagonists was assessed with confocal laser scanning microscopy and flow cytometry. Cell death was assessed with MTT assay and VEGF secretion was measured with ELISA. When clinical doses were applied for 1 h, Bevacizumab was taken up by RPE cells as assessed by confocal laser scanning microscopy and flow cytometry. After 24 h of incubation, and further assessed after 1d, 5d, and 7d, Bevacizumab was detected in RPE cells where it accumulated over time. The presence of Bevacizumab within RPE cells after 7d was confirmed by flow cytometry. While some Ranibizumab was found in RPE cells after 1 h of incubation when assessed with confocal laser microscopy but not by flow cytometry, no signal above control was detected after 1d, 5d, or 7d. Neither substance induced significant cell death after 7 days and no inhibitory effect on VEGF secretion was observed after day 3 of culture. Bevacizumab, but not Ranibizumab, accumulates in RPE cells over time, implying substantial differences between these two drugs.

Neutralizing Endogenous VEGF Following Traumatic Spinal Cord Injury Modulates Microvascular Plasticity but not Tissue Sparing or Functional Recovery

Acute loss of spinal cord vascularity followed by an endogenous adaptive angiogenic response with concomitant microvascular dysfunction is a hallmark of traumatic spinal cord injury (SCI). Recently, the potent vasoactive factor vascular endothelial growth factor (VEGF) has received much attention as a putative therapeutic for the treatment of various neurodegenerative disorders, including SCI. Exogenous VEGF exerts both protective and destabilizing effects on microvascular elements and tissue following SCI but the role of endogenous VEGF is unclear. In the present study, we systemically applied a potent and well characterized soluble VEGF antagonist to adult C57Bl/6 mice post-SCI to elucidate the relative contribution of VEGF on the acute evolving microvascular response and its impact on functional recovery. While the VEGF Trap did not alter vascular density in the injury epicenter or penumbra, an overall increase in the number of Griffonia simplicifolia isolectin-B4 bound microvessels was observed, suggesting a VEGF-dependency to more subtle aspects of endothelial plasticity post-SCI. Neutralizing endogenous VEGF neither attenuated nor exacerbated chronic histopathology or functional recovery. These results support the idea that overall, endogenous VEGF is not neuroprotective or detrimental following traumatic SCI. Furthermore, they suggest that angiogenesis in traumatically injured spinal tissue is regulated by multiple effectors and is not limited by endogenous VEGF activation of affected spinal microvessels.

Gene expression and silencing for improved islet transplantation

Islet transplantation has great potential as an effective means of treating type 1 diabetes. However, its successful application greatly depends on the rapid revascularization of islets and prevention from their apoptotic cell death. We co-expressed human vascular endothelial growth factor (hVEGF) and human interleukin-1 receptor antagonist (hIL-1Ra) after transduction of human islets with Adv-hVEGF-hIL-1Ra. Since hepatocyte growth factor (HGF) increases β-cell proliferation and promotes revascularization of islets, we also constructed Adv-hHGF-hIL-1Ra. There was dose and time dependent expression of hVEGF and hIL-1Ra or hHGF and hIL-1Ra by islets, which led to decrease in caspase-3 activity and apoptosis induced by a cocktail of TNF-α, IL-1β and IFN-γ. Compared to non-treated islets, transduction of islets with these bipartite Adv vectors prior to transplantation under the kidney capsules of diabetic NOD-SCID mice reduced the blood glucose levels, and increased serum insulin and c-peptide levels. Immunohistochemical staining of the islet bearing kidney sections was positive for human insulin, growth factor (hVEGF or hHGF) and von Willebrand factor. Transduction with Adv-caspase-3-shRNA also prevented islets from cytokine induced apoptosis and improved islet transplantation. In conclusion, bipartite Adv vector efficiently co-expressed both growth factor and antiapoptotic genes or shRNA targeting pro-apoptotic genes, decreases apoptosis and improves the outcome of islet transplantation.

Paracrine action of sFLT‐1 secreted by stably‐transfected Ehrlich ascites tumor cells and therapy using sFLT‐1 inhibits ascites tumor growth in vivo

Vascular endothelial growth factor (VEGF) is known to play a major role in angiogenesis. A soluble form of Flt-1, a VEGF receptor, is potentially useful as an antagonist of VEGF, and accumulating evidence suggests the applicability of sFlt-1 in tumor suppression. In the present study, we have developed and tested strategies targeted specifically to VEGF for the treatment of ascites formation. As an initial strategy, we produced recombinant sFLT-1 in the baculovirus expression system and used it as a trap to sequester VEGF in the murine ascites carcinoma model. The effect of the treatment on the weight of the animal, cell number, ascites volume and proliferating endothelial cells was studied. The second strategy involved, producing Ehrlich ascites tumor (EAT) cells stably transfected with vectors carrying cDNA encoding truncated form of Flt-1 and using these cells to inhibit ascites tumors in a nude mouse model. The sFLT-1 produced by the baculovirus system showed potent anti-angiogenic activity as assessed by rat cornea and tube formation assay. sFLT-1 treatment resulted in reduced peritoneal angiogenesis with a concomitant decrease in tumor cell number, volume of ascites, amount of free VEGF and the number of invasive tumor cells as assayed by CD31 staining. EAT cells stably transfected with truncated form of Flt-1 also effectively reduced the tumor burden in nude mice transplanted with these cells, and demonstrated a reduction in ascites formation and peritoneal angiogenesis. The inhibition of peritoneal angiogenesis and tumor growth by sequestering VEGF with either sFlt-1 gene expression by recombinant EAT cells or by direct sFLT-1 protein therapy is shown to comprise a potential therapy.

Correlation of electroretinography b-wave absolute latency, plasma levels of human basic fibroblast growth factor, vascular endothelial growth factor, soluble fatty acid synthase, and adrenomedullin in diabetic retinopathy

Background We investigated the b-wave latency of electroretinogram (ERG), human basic fibroblast growth factor (b-FGF), vascular endothelial growth factor (VEGF), soluble fatty acid synthase (s-Fas), and adrenomedullin (ADM) in diabetic retinopathy. Patients and Methods Thirty control and 60 type II diabetic women (mean age 45±3.9 years, duration of diabetes 10.1±2.1 years) were investigated. Diabetics without complications (Group II) and with retinopathy (Group III) were diagnosed depending on clinical findings, abnormal fundus examination, and ERG. Plasma levels of b-FGF, VEGF, s-Fas, and ADM were measured. Results ERG showed a significant increase of b-wave absolute latency, plasma b-FGF, VEGF, s-Fas, and ADM in diabetic retinopathy ( P<.05). A positive correlation was found between b-wave latency and VEGF and s-Fas, and a negative correlation with b-FGF and ADM. Conclusion This study elucidates the causative role of VEGF and s-Fas in diabetic retinopathy. VEGF may potently promote growth of endothelial cells and formation of new vessels implicated in proliferative retinopathy. s-Fas could be involved in advancement of apoptotic changes in retinopathy and high levels of b-FGF, and ADM may be compensatorily neuroprotective and vasculoprotective. The results showed that diabetic retinopathy is the result of multiple factors, so it is optimistic to believe that reversing VEGF or s-Fas will halt retinopathy, targeting multiple mechanisms simultaneously by administering combination treatments of VEGF antagonists; antiapoptotic drugs together with b-FGF and/or ADM may be prospective.