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At least 433 records · Page 24Linked to original sources

PubMed2002

Uveal melanomas express vascular endothelial growth factor and basic fibroblast growth factor and support endothelial cell growth.

BACKGROUND: Tumour microvascularity is a significant determinant of prognosis for a large number of different tumours, including uveal melanoma. The development of blood vessels within these and other tumours is partly controlled by soluble pro-angiogenic cytokines, of which basic fibroblast growth factor (bFGF) and vascular endothelial growth factor-A (VEGF) are the best described. METHODS: Because VEGF has been inconsistently found within uveal melanomas and bFGF is described as an autocrine growth factor in cutaneous melanoma, the authors looked at the expression of these cytokines in uveal melanomas using immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR). The cross talk between uveal melanoma cells and endothelial cells was then assessed in an in vitro co-culture model. RESULTS: While most tumour cells expressed bFGF at the protein level by immunohistochemistry (89%), relatively few (22%) expressed VEGF, and this was of limited extent. All 20 tumours tested by RT-PCR contained mRNA for both bFGF and VEGF. Co-culture experiments using an ATP based bioassay showed that uveal melanomas could support the growth of a rat brain endothelial cell line (GPNT) and human umbilical vein endothelial cells (HUVEC), and that this could be modulated by cytokines and anti-cytokine antibodies. CONCLUSION: These results suggest that angiogenesis within uveal melanoma may be the result of a complex interplay between endothelial and tumour cells, and that bFGF and VEGF could play a part.

Adenosine Triphosphate↗

PubMed2001

Oxidized LDL regulates vascular endothelial growth factor expression in human macrophages and endothelial cells through activation of peroxisome proliferator-activated receptor-gamma.

Vascular endothelial growth factor (VEGF) has been recognized as an angiogenic factor that induces endothelial proliferation and vascular permeability. Recent studies have also suggested that VEGF can promote macrophage migration, which is critical for atherosclerosis. We have reported that VEGF is remarkably expressed in activated macrophages, endothelial cells, and smooth muscle cells within human coronary atherosclerotic lesions, and we have proposed the significance of VEGF in the progression of atherosclerosis. To clarify the mechanism of VEGF expression in atherosclerotic lesions, we examined the regulation of VEGF expression by oxidized low density lipoprotein (Ox-LDL), which is abundant in atherosclerotic arterial walls. A recent report has revealed that peroxisome proliferator-activated receptor-gamma (PPARgamma) is expressed not only in adipocytes but also in monocytes/macrophages and has suggested that PPARgamma may have a role in the differentiation of monocytes/macrophages. Furthermore, 9- and 13-hydroxy-(S)-10,12-octadecadienoic acid (9- and 13-HODE, respectively), the components of Ox-LDL, may be PPARgamma ligands. Therefore, we investigated the involvement of PPARgamma in the regulation of VEGF by Ox-LDL. PPARgamma expression was detected in human monocyte/macrophage cell lines, human acute monocytic leukemia (THP-1) cells, and human coronary artery endothelial cells (HCAECs). Ox-LDL (10 to 50 microg/mL) upregulated VEGF secretion from THP-1 dose-dependently. VEGF mRNA expression in HCAECs was also upregulated by Ox-LDL. The mRNA expression of VEGF in THP-1 cells and HCAECs was also augmented by PPARgamma activators, troglitazone (TRO), and 15-deoxy-(12,14)-prostaglandin J(2) (PGJ2). In contrast, VEGF expression in another monocyte/macrophage cell line, human histiocytic lymphoma cells (U937), which lacks PPARgamma expression, was not augmented by TRO or PGJ2. We established the U937 cell line, which permanently expresses PPARgamma (U937T). TRO and Ox-LDL augmented VEGF expression in U937T. In addition, VEGF production by THP-1 cells was significantly increased by exposure to 9-HODE and 13-HODE. In conclusion, Ox-LDL upregulates VEGF expression in macrophages and endothelial cells, at least in part, through the activation of PPARgamma.

Arteriosclerosis↗

PubMed2002

CD40 ligand inhibits endothelial cell migration by increasing production of endothelial reactive oxygen species.

BACKGROUND: The CD40/CD40 ligand system is involved in atherogenesis. Activated T lymphocytes and platelets, which express high amounts of CD40 ligand (CD40L) on their surface, contribute significantly to plaque instability with ensuing thrombus formation, leading to acute coronary syndromes. Because reendothelialization may play a pivotal role for plaque stabilization, we investigated a potential role of CD40L on endothelial cell (EC) migration. METHODS AND RESULTS: Stimulation of ECs with recombinant CD40L prevented vascular endothelial growth factor (VEGF)-induced EC migration, as determined by a "scratched wound assay." In addition, activated T lymphocytes and platelets significantly inhibited VEGF-induced EC migration and tube formation in vitro. Because the activation of endothelial nitric oxide (NO) synthase and the release of NO are required for EC migration and angiogenesis, we analyzed the effect of NO. Coincubation with the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) did not reverse the inhibitory effect of CD40L on VEGF-induced EC migration and tube formation. In addition, EC migration induced by SNAP was completely inhibited by CD40L. CD40L, however, induced the production of reactive oxygen species and reduced endothelial NO bioavailability. This reactive oxygen species-dependent effect of CD40L stimulation was reversed with vitamin C or N-acetylcysteine. CONCLUSIONS: The activation of the CD40 receptor inhibits EC migration by increasing reactive oxygen species. The blockade of EC migration by CD40L may critically affect endothelial regeneration after plaque erosion and thereby may contribute to the increased risk for development of acute coronary events in patients with high circulating levels of CD40L.

Antioxidants↗

PubMed2004

Vascular endothelial growth factor receptor-2-induced initial endothelial cell migration depends on the presence of the urokinase receptor.

The angiogenic response of endothelial cells initiated by different growth factors is accompanied by assembly of cell surface-bound proteolytic machinery as a prerequisite for focal invasion. We have shown previously how the vascular endothelial growth factor (VEGF) initiates proteolysis by activation of pro-urokinase (pro-PA) via the VEGF receptor-2 (VEGFR-2). We now show that the cell surface receptor of the uPA-system, the urokinase receptor (uPAR), is redistributed to focal adhesions at the leading edge of endothelial cells in response to VEGF. VEGF165 and VEGF-E, both interacting with VEGFR-2, but not PlGF exclusively stimulating VEGFR-1, induce within minutes internalization of uPAR via an LDL receptor-like molecule, dependent on generation of active uPA and the presence of plasminogen activator inhibitor-1 (PAI-1). uPAR seems to play a pivotal role in VEGFR-2-induced endothelial cell migration because cleavage of surface uPAR impaired the migratory response of endothelial cells toward VEGF-E, but not toward PlGF.

Animals↗

PubMed2000

Vascular endothelial growth factor(165) gene transfer augments circulating endothelial progenitor cells in human subjects.

Preclinical studies in animal models and early results of clinical trials in patients suggest that intramuscular injection of naked plasmid DNA encoding vascular endothelial growth factor (VEGF) can promote neovascularization of ischemic tissues. Such neovascularization has been attributed exclusively to sprout formation of endothelial cells derived from preexisting vessels. We investigated the hypothesis that VEGF gene transfer may also augment the population of circulating endothelial progenitor cells (EPCs). In patients with critical limb ischemia receiving VEGF gene transfer, gene expression was documented by a transient increase in plasma levels of VEGF. A culture assay documented a significant increase in EPCs (219%, P<0.001), whereas patients who received an empty vector had no change in circulating EPCs, as was the case for volunteers who received saline injections (VEGF versus empty vector, P<0.001; VEGF versus saline, P<0.005). Fluorescence-activated cell sorter analysis disclosed an overall increase of up to 30-fold in endothelial lineage markers KDR (VEGF receptor-2), VE-cadherin, CD34, alpha(v)beta(3), and E-selectin after VEGF gene transfer. Constitutive overexpression of VEGF in patients with limb ischemia augments the population of circulating EPCs. These findings support the notion that neovascularization of human ischemic tissues after angiogenic growth factor therapy is not limited to angiogenesis but involves circulating endothelial precursors that may home to ischemic foci and differentiate in situ through a process of vasculogenesis.

Adult↗

PubMed2000

Acidosis inhibits endothelial cell apoptosis and function and induces basic fibroblast growth factor and vascular endothelial growth factor expression.

Endothelial cells are exposed to an acidotic environment in a variety of pathological and physiological conditions. However, the effect of acidosis on endothelial cell function is still largely unknown, and it was evaluated in the present study. Bovine aortic endothelial cells (BAECs) were grown in bicarbonate buffer equilibrated either with 20% CO(2) (pH 7.0, acidosis) or 5% CO(2) (pH 7.4, control). Acidosis inhibited BAEC proliferation in 10% FCS, whereas by day 7 in serum-free medium, cell number was 3-fold higher in acidotic cells than in control cells. Serum deprivation enhanced BAEC apoptosis, and apoptotic cell death was markedly inhibited by acidosis. Additionally, acidosis inhibited FCS-stimulated migration in a modified Boyden chamber assay and FCS-stimulated differentiation into capillary-like structures on reconstituted basement membrane proteins. Conditioned media from BAECs cultured for 48 hours either at pH 7.0 or pH 7.4 enhanced BAEC proliferation and migration at pH 7.4, and both effects were more marked with conditioned medium from BAECs grown in acidotic than in control conditions. Acidosis enhanced vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) mRNA expression as well as bFGF secretion, and a blocking bFGF antibody inhibited enhanced BAEC migration in response to conditioned medium from acidotic cells. These results show that acidosis protects endothelial cells from apoptosis and inhibits their proangiogenic behavior despite enhanced VEGF and bFGF mRNA expression and bFGF secretion.

Acidosis↗

PubMed1999

Induction of vascular endothelial growth factor expression in endothelial cells by platelet-derived growth factor through the activation of phosphatidylinositol 3-kinase.

Increased numbers of platelet-derived growth factor beta receptors betaPPDGFRs) on neovascular endothelial cells is a common occurrence in several pathological conditions including wound healing, inflammation, and glioma tumorigenesis. Here we sought to test the biological significance of this by determining whether expression of wild-type betaPDGFR by normal aortic endothelial cells affected the expression of the vascular endothelial growth factor (VEGF), a critical angiogenesis regulator and mitogen for such cells. The results showed that PDGF could increase transcription and secretion of VEGF by betaPDGFR-expressing endothelial cells. Moreover, we further demonstrated a requirement for the activation of phosphatidylinositol 3-kinase (PI3K) in this response by using chemical inhibitors of PI3K, mutant PDGFR, and dominant-negative PI3K. These studies suggest a novel mechanism by which PDGF induces VEGF expression in endothelial cells, define VEGF as a downstream target for PI3K, and invoke a role for PI3K in angiogenesis.

Dose-Response Relationship, Drug↗

PubMed2001

Vascular endothelial growth factor enhances the expression of urokinase receptor in human endothelial cells via protein kinase C activation.

Among other proteolytic enzymes, the urokinase-type plasminogen activator (u-PA)/plasmin cascade contributes to cell migration and the formation of capillary-like structures in a fibrinous exudate. The u-PA receptor (u-PAR) focuses proteolytical activity on the cell surface of the endothelial cell and hereby accelerates the pericellular matrix degradation. Vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF)-2 enhance u-PA receptor expression in human endothelial cells. In this paper we show that the protein kinase C (PKC) inhibitors Ro31-8220 and GF109203X inhibit VEGF165-induced u-PAR antigen expression in human endothelial cells, whereas PKC inhibition had no effect on FGF-2-induced u-PAR antigen enhancement. In addition, inhibition of PKC activity had no effect on VEGF165- or FGF-2-induced proliferation in human endothelial cells. We conclude that VEGF165 induces u-PAR via a PKC-dependent pathway, whereas proliferation is induced via a different pathway probably involving tyrosine phosphorylation of proteins downstream of the VEGF receptors.

Cell Division↗

PubMed2001

The antiangiogenic property of docetaxel is synergistic with a recombinant humanized monoclonal antibody against vascular endothelial growth factor or 2-methoxyestradiol but antagonized by endothelial growth factors.

Numerous chemotherapeutic agents have been shown to have an inhibitory effect on endothelial cell proliferation and migration, and tubule formation. In this study, we examined the antiangiogenic activity of docetaxel. Docetaxel inhibited endothelial cell proliferation and tubule formation in vitro in a dose-dependent fashion. Docetaxel treatment also inhibited angiogenesis in an in vivo Matrigel plug assay. The endothelial stimulating factors, vascular endothelial cell growth factor (VEGF) and basic fibroblast growth factor are able to protect endothelial cells from the antiangiogenic properties of docetaxel. This protective effect can be overcome by a recombinant humanized monoclonal antibody directed against VEGF in both in vitro and in vivo models. Similarly, combination of docetaxel with the antiangiogenic agent 2-methoxyestradiol also overcomes the protective effect of VEGF in both in vitro and in vivo models. These data suggest that microenvironmental factors (e.g., local release of VEGF and basic fibroblast growth factor) could play a role in decreasing the antiangiogenic effects of docetaxel, whereas agents such as 2- methoxyestradiol and recombinant humanized monoclonal antibody directed against VEGF may reverse this protective effect.

2-Methoxyestradiol↗

PubMed2001

Synergistic induction of t-PA by vascular endothelial growth factor and basic fibroblast growth factor and localization of t-PA to Weibel-Palade bodies in bovine microvascular endothelial cells.

Endothelial cell migration is stimulated by members of the vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) families, and is dependent on extracellular proteolytic activity provided by enzymes of the plasminogen activator (PA) system. Here we report that in bovine microvascular endothelial cells (BME cells), bFGF principally increased urokinase-type PA (u-PA) while tissue-type PA (t-PA) was increased mainly by VEGF. In bovine aortic endothelial cells (BAE cells), bFGF increased u-PA, whereas VEGF had no effect. Co-added bFGF and VEGF increased t-PA mRNA levels and enzyme activity in both cell types in a synergistic manner. Tissue-type plasminogen activator (t-PA) immunoreactivity colocalized with von Willebrand factor, a marker for Weibel-Palade bodies. Co-added bFGF and VEGF increased the number of t-PA-positive cells as well as the number of t-PA-positive granules per cell. Localization of t-PA in regulated storage granules endows endothelial cells with the potential to rapidly increase proteolytic activity in the pericellular environment.

Animals↗

PubMed2001

[Triptolide inhibits vascular endothelial growth factor expression and production by endothelial cells].

OBJECTIVE: To investigate the effect of triptolide on vascular endothelial growth factor (VEGF) expression and secretion by endothelial cells, and explore the mechanism of anti-proteinuric effect of triptolide on glomerular nephritis. METHOD: A human umbilical endothelium derived cell line (ECV-304) from American Type Culture Collection(ATCC) was used in this study. The effects of triptolide on VEGF mRNA expression, and intracellular protein production and secretion induced by PMA were measured by RT-PCR, flow cytometry and enzyme linked immunosorbent assay (ELISA). The effects of triptolide on endothelial c-jun/c-fos mRNA expression were investigated by RT-PCR. RESULTS: 100 ng/ml PMA significantly increased VEGF mRNA expression, intracellular production and secretion of VEGF in endothelial cells, while triptolide inhibited the effects of PMA in a dose-dependent manner. Moreover, triptolide dose-dependently inhibited endothelial c-jun/c-fos mRNA expression. CONCLUSION: Triptolide is a potent inhibitor of VEGF expression and production, suggesting that the inhibitory influence of triptolide on VEGF expression and production may be one of the mechanisms underlying its anti-proteinuric effect on glomerular nephritis. Triptolide might inhibit VEGF expression and production by interfering with transcription factor AP-1 formation.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2005

[Effect of monoclonal antibody against extracellular domain III of vascular endothelial growth factor receptor KDR on proliferation of vascular endothelial cells].

OBJECTIVE: To prepare a neutralizing monoclonal antibody (McAb) against vascular endothelial growth factor receptor KDR and study its biological activity. METHODS: Extracellular immunoglobulin (Ig)-like domain III of KDR (KDR III) was expressed in E. coli and purified by affinity chromatograph. Monoclonal antibody against KDR III was prepared by hybridoma technique. ELISA and FACS analysis were used to identify its specificity. Immunoprecipitation and [(3)H]-TdR incorporation assay were also used to detect the activity of anti-KDR McAb blocking the phosphorylation of KDR tyrosine kinase receptor and the influence on VEGF-induced mitogenesis of human endothelial cells. RESULTS: McAb Ycom1D3 against KDR III was prepared which bound specifically to both the soluble KDR III and the cell-surface expressed KDR. It effectively blocked VEGF/KDR interaction and inhibited VEGF-stimulated activation of KDR expression on human endothelial cells. Furthermore, Ycom1D3 efficiently neutralized VEGF-induced mitogenesis of human umbilical vascular endothelial cells. CONCLUSION: McAb Ycom1D3 against KDR III may suppress the action of VEGF by blocking native vascular endothelial growth factor receptor KDR. It has potential clinical applications in the treatment of cancers and other diseases where pathological angiogenesis is involved.

Antibodies, Monoclonal↗

PubMed1995

Hypoxic induction of endothelial cell growth factors in retinal cells: identification and characterization of vascular endothelial growth factor (VEGF) as the mitogen.

BACKGROUND: New vessel growth is often associated with ischemia, and hypoxic tissue has been identified as a potential source of angiogenic factors. In particular, ischemia is associated with the development of neovascularization in a number of ocular pathologies. For this reason, we have studied the induction of endothelial cell mitogens by hypoxia in retinal cells. MATERIALS AND METHODS: Human retinal pigment epithelium (hRPE) were grown under normoxic and hypoxic conditions and examined for the production of endothelial mitogens. Northern analysis, biosynthetic labeling and immunoprecipitation, and ELISA were used to assess the levels of vascular endothelial growth factor/vascular permeability factor (VEGF) and basic fibroblast growth factor (bFGF), two endothelial cell mitogens and potent angiogenic factors. Soluble receptors for VEGF were employed as competitive inhibitors to determine the contribution of the growth factor to the hypoxia-stimulated mitogen production. RESULTS: Following 6-24 hr of hypoxia, confluent and growing cultures of hRPE increase their levels of VEGF mRNA and protein synthesis. Biosynthetic labeling studies and RT-PCR analysis indicate that the cells secrete VEGF121 and VEGF165, the soluble forms of the angiogenic factor. In contrast, hRPE cultured under hypoxic conditions show reduced steady-state levels of basic fibroblast growth factor (bFGF) mRNA and decreased bFGF protein synthesis. Unlike VEGF, bFGF is not found in conditioned media of hRPE following 24 hr of hypoxia. Using a soluble high-affinity VEGF receptor as a competitive inhibitor of VEGF, we demonstrate that a VEGF-like activity is the sole hypoxia-inducible endothelial mitogen produced by cultured hRPE. CONCLUSIONS: From this comparison we conclude that hRPE do not respond to hypoxia with a general, nonspecific increase in the overall levels of growth factors, as is seen during cell wounding responses or serum stimulation. The physiological relevance of data from this in vitro model are affirmed by separate studies in an animal model of retinal ischemia-induced ocular neovascularization (1) in which retina-derived VEGF levels have been shown to correlate spatio-temporally with the onset of angiogenesis. Taken together, these data support the hypothesis that the induction of VEGF by hypoxia mediates the rapid, initial angiogenic response to retinal ischemia.

Alternative Splicing↗

PubMed1996

Influence of vascular endothelial growth factor on bovine corneal endothelial cells in a wound-healing model.

In this study we determined the influence of vascular endothelial growth factor (VEGF) on bovine corneal endothelial cell proliferation and wound healing. Proliferation was determined by measurement of DNA replication as well as by counting of the number of cells present after a defined growth period. In a wound-healing model, reproducible cell-free areas were created within monolayers of cultured bovine corneal endothelial cells and the migration of the cells into these areas was analyzed. The DNA replication and cell proliferation of bovine corneal endothelial cells were not influenced by VEGF. In contrast, in the wound-healing model, VEGF supplementation at concentrations of 1 and 10 ng/ml increased the cell density of the wounded area by 20% and 50%, respectively, as compared with the cell density of wounds left untreated by VEGF. Furthermore, no increase in DNA replication was found in cells involved in wound healing. Our results demonstrate that healing of bovine corneal endothelial cell layers after wounding is predominantly performed by cell migration rather than by proliferation. This migration can be stimulated by the addition of exogenous VEGF.

Animals↗

PubMed1996

Vascular endothelial growth factor stimulates protein kinase C-dependent phospholipase D activity in endothelial cells.

Many tumors produce vascular endothelial growth factor (VEGF), a paracrine factor acting selectively on endothelial cells. VEGF has many effects on cultured endothelial cells and mediates angiogenesis and enhanced vascular permeability in vivo. The endothelial signal transduction pathways of VEGF represent novel targets for cancer therapy because they are readily accessible to systemically administered drugs. We have examined VEGF-stimulated signals generated in HUVEC to identify potential targets for therapeutic intervention. The transphosphatidylation reaction has been used to monitor phospholipase D (PLD) activity; total inositol phosphates have been measured after prelabeling of cells with [3H]myoinositol; and intracellular free calcium has been measured using Fura-2 fluorescence. After HUVEC-stimulation with VEGF, there is an early influx of calcium (maximal by 100 seconds) followed by activation of PLD (half maximal by 100 seconds, EC50 70 pm). The PLD activity was inhibited by reducing extracellular calcium (150 nM, 50% inhibition), exposure to 12-O-tetradecanoylphorbol 13 acetate (200 nM, 24 hours, 100% inhibition), Roche 31,8220 (10 microM, 15 minutes, 72% inhibition), or genestein (100 microM, 30 minutes, 56% inhibition), which suggests a dependence on both protein kinase C and tyrosine phosphorylation. Activation of phospholipase C-catalyzed hydrolysis of phosphatidylinositol-4,5-bisphosphate was inferred from the production of inositol phosphates, although this response was slower (half maximal by 3 minutes). The phospholipase C activity was also dependent on influx of calcium and was partially inhibited by low (150 nM) extracellular calcium. PLD may be involved in mediating a number of endothelial responses to tumor-secreted VEGF, notably cytoskeleton-dependent effects such as the cell migration involved in angiogenesis. This signal transduction pathway could represent an accessible and vulnerable target for cancer therapeutic intervention and has the novelty of being located within normal cells rather than tumor cells.

Calcium↗

PubMed1997

Inhibition of vascular endothelial growth factor-induced endothelial cell migration by ETS1 antisense oligonucleotides.

Vascular endothelial growth factor (VEGF) increased the level of ETS1 mRNA in human umbilical vein endothelial cells (HUVEC) and human lung microvascular endothelial cells (HMVEC-L) over 5-fold. Protein levels were shown to increase concordantly. VEGF was also found to stimulate the invasiveness of endothelial cells as measured by migration through Matrigel- or gelatin-coated membranes. The VEGF-induced invasiveness was inhibited by ETS1 antisense oligonucleotides but not by a sense control. In addition, the ETS1 antisense oligonucleotides reduced the levels of ETS1 and urokinase-type plasminogen activator mRNAs. The antisense oligonucleotides directed against the ETS1 gene thus altered a cellular property of endothelial cells that is correlated with the ability of the cells to migrate through basement membranes. Together, these observations demonstrate a direct role for the ETS1 gene in angiogenesis.

Cell Division↗

PubMedDate not supplied

Stimulation of growth and migration of vascular endothelial cells by vascular endothelial growth factor transduced smooth muscle cells in co-culture.

Vascular endothelial growth factor (VEGF) is a secreted mitogen with high specificity toward endothelial cells. Expression of VEGF by smooth muscle cells in vivo may be an important stimulus for the regrowth of the endothelium after damage caused by interventions such as angioplasty. The levels of VEGF secreted by cultured smooth muscle cells minimally stimulated growth of endothelial cells in co-culture. Full length cDNA for the 165 amino acid residue, bovine VEGF (VEGF165), was isolated from calf liver total RNA by reverse transcriptase polymerase chain reaction (RT-PCR) techniques, and used to generate plasmid constructs for transfection. Bovine aortic smooth muscle cells (BSMC), stably transfected with VEGF165 plasmid DNA, secreted mitogen into conditioned culture medium at levels that are physiologically relevant (2-4 ng/ml). Transformed BSMC stimulated growth of bovine aortic endothelial cells (BAEC) in co-culture, to a significantly greater extent than mock transfected BSMC. Migration of BAEC was also enhanced by the presence of VEGF transduced BSMC. These data suggest that smooth muscle cells, genetically engineered to produce VEGF, may provide biologic linings in cardiovascular prostheses that could promote the growth of endogenous endothelial cells.

Animals↗

PubMed1998

Hypoxia and vascular endothelial growth factor stimulate angiogenic integrin expression in bovine retinal microvascular endothelial cells.

PURPOSE: Integrins alphavbeta3 and alphavbeta5 are cell-to-matrix adhesion molecules that have been reported to mediate vascular cell proliferation and migration. The authors investigated the regulation of expression of these angiogenic integrins by hypoxia and vascular endothelial growth factor (VEGF) in retinal microvascular endothelial cells in culture. METHODS: Cultured bovine retinal capillary endothelial cells were exposed to human recombinant VEGF under normoxic (95% air, 5% CO2) conditions to assess the effects of VEGF. Hypoxia studies were performed under lower oxygen concentration (0.5%-1.5% O2) induced by nitrogen replacement in constant 5% CO2 conditions. Integrin family mRNA and protein expression were assessed by northern blot analysis and immunoprecipitation. RESULTS: VEGF (25 ng/ml) increased integrin alphav, beta3, and 35 mRNA after 24 hours 6.1+/-0.8-fold (P < 0.001), 5.9+/-1.1-fold (P < 0.001), and 1.9+/-0.2-fold (P < 0.01), respectively. Similarly, hypoxia stimulated gene expression of integrin alphav and beta3 after 24 hours by 5.1+/-1.7-fold (P < 0.01) and 3.0+/-0.5-fold (P < 0.01), respectively, and integrin beta5 after 9 hours 1.4+/-0.2-fold (P < 0.05). This hypoxia-induced, integrin alphav mRNA elevation was inhibited significantly by anti-VEGF neutralizing antibody. Also, a conditioned medium from confluent endothelial cells maintained under hypoxic conditions for 24 hours produced a 7.1+/-1.1-fold increase (P < 0.001) in integrin alphav mRNA expression after 24 hours, which was reversed by anti-VEGF neutralizing antibody. Induction of integrin alphav by VEGF and hypoxia was confirmed in the protein level. CONCLUSIONS: These data suggest that hypoxia stimulates expression of vascular integrins alphavbeta3 and alphavbeta5 in retinal microvascular endothelial cells partially through autocrine-paracrine action of VEGF induced by the hypoxic state.

Animals↗