(Circulation. 2000;102:185.)
© 2000 American Heart Association, Inc.
Clinical Investigation and Reports |
Vascular Endothelial Growth Factor-A–Induced Chemotaxis of Monocytes Is Attenuated in Patients With Diabetes Mellitus
A Potential Predictor for the Individual Capacity to Develop Collaterals
From the Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany.
Correspondence to Johannes Waltenberger, MD, Department of Internal Medicine II (Cardiology), Ulm University Medical Center, Robert-Koch-Str 8, D-89081 Ulm, Germany. E-mail johannes.waltenberger{at}medizin.uni-ulm.de
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Background—Vascular endothelial growth factor-A (VEGF-A) acts on endothelial cells and monocytes, 2 cell types that participate in the angiogenic and arteriogenic process in vivo. Thus far, it has not been possible to identify differences in individual responses to VEGF-A stimulation because of the lack of an ex vivo assay.
Methods and Results—We report a chemotaxis assay using isolated monocytes from individual diabetic patients and from healthy, age-matched volunteers. The chemotactic response of individual monocyte preparations to VEGF-A, as mediated via Flt-1, was quantitatively assessed using a modified Boyden chamber. Although the migration of monocytes from healthy volunteers could be stimulated with VEGF-A (1 ng/mL) to a median of 148.4% of the control value (25th and 75th percentiles, 136% and 170%), monocytes from diabetic patients could not be stimulated with VEGF-A (median, 91.1% of unstimulated controls; 25th and 75th percentiles, 83% and 98%; P<0.0001). In contrast, the response of monocytes to the chemoattractant formylMetLeuPhe remained intact in diabetic patients. The VEGF-A–inducible kinase activity of Flt-1, as assessed by in vitro kinase assays, remained intact in monocytes from diabetic patients. Moreover, the serum level of VEGF-A, as assessed by immunoradiometric assay, was significantly elevated in diabetic patients.
Conclusions—The cellular response of monocytes to VEGF-A is attenuated in diabetic patients because of a downstream signal transduction defect. These data suggest that monocytes are important in arteriogenesis and that their ability to migrate might be critical to the arteriogenic response. Thus, we resolved a fundamental mechanism involved in the problem of impaired collateral formation in diabetic patients.
Key Words: collateral circulation • diabetes mellitus • signal transduction • cell movement • monocytes • endothelial growth factors
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Vascular endothelial growth factor-A (VEGF-A) and its receptors are crucially involved in the process of angiogenesis, as several gene knockout experiments have shown.1 2 3 4 In addition, VEGF-A can induce an angiogenic response and enhance collateral blood flow when administered to an area of regional myocardial or peripheral ischemia.5 6 7 8 9 Therefore, it is important to investigate the cellular responses to VEGF-A stimulation under the pathological conditions that might affect or limit its function and use. Such conditions include diabetes mellitus, a prominent cardiovascular risk factor.10
VEGF-A was initially described as an endothelial cell-specific growth factor that could stimulate endothelial proliferation and migration in vitro11 and angiogenesis and endothelial cell regrowth in vivo.12 VEGF-A recently gained enormous attention in the medical community for the following 2 reasons. (1) It is crucially involved in the pathogenesis of a number of different angiogenic diseases, including diabetic retinopathy, psoriasis, rheumatoid arthritis, and the growth of solid tumors.13 (2) Local or regional VEGF-A application enhances blood flow to areas of regional ischemia, thereby stimulating tissue perfusion. This concept is known as "therapeutic angiogenesis"6 and was initially introduced by Höckel and Burke14 in a noncardiac context. In fact, several clinical trials are currently underway to prove the feasibility and efficiency of improving myocardial perfusion by using VEGF-A.15 16
The concept of therapeutic angiogenesis has been studied in detail in the context of regional ischemia in the heart, in the peripheral circulation, and in the brain. Most recently, the concept of arteriogenesis, ie, the growth of preexisting collaterals, is evolving; this requires discrimination from true angiogenesis.17 In light of this discrimination, the term therapeutic angiogenesis, although extensively used in the past, should no longer be used to describe the stimulation of true collateral growth; the term "therapeutic arteriogenesis" seems to be more appropriate.
The cellular effects of VEGF-A are mediated via 2 distinct receptor tyrosine-kinases11 called Flt-1 (Fms-like tyrosine kinase [VEGFR1]) and KDR (kinase-insert domain-containing receptor [VEGFR2]). In previous studies on the function of KDR, we found in vitro evidence for the regulation of receptor activity under pathological conditions such as hypoxia.
Besides endothelial cells, monocytes specifically respond to VEGF-A. One of the 2 VEGF-receptors (Flt-1) is present on the surface of monocytes and mediates the chemotactic response to VEGF-A and tissue factor induction.18 What makes monocytes especially attractive is the fact that they represent the only cell type in the body that carries receptors for VEGF and, at the same time, can be obtained from individual patients for functional analysis of the VEGF receptor system. Moreover, monocytes play an important role in the angiogenic process and during collateral growth/arteriogenesis.19 20 So far, there was no experimental approach to judge the individual response to VEGF-A stimulation in a defined patient. Given the possibility of obtaining such data, this would be an extremely important piece of information in the context of stimulating collateral formation.
On the basis of these ideas, we developed and established an assay in which peripheral blood monocytes can be isolated from individuals and tested for their chemotactic response to VEGF-A in a modified Boyden chamber. We found that the specific and strong VEGF-A–induced response seen in healthy individuals is completely attenuated in patients with diabetes mellitus. We conclude that monocytes can be used to determine VEGF receptor–mediated cellular function in healthy and diseased individuals. Given the crucial role of monocytes in the development of functional collaterals, the impaired chemotactic response of monocytes to VEGF-A in diabetic patients seems to predict a reduced ability to grow collaterals. The analysis of the VEGF-A–induced migration of monocytes represents the first attempt to study the function of the VEGF system in healthy and diseased individuals.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Characterization of Patients and Healthy Volunteers
Patients with diabetes mellitus (n=16; 6 men and 10 women) and a mean age of 68.3±10.4 years were studied; this group included both patients with insulin-dependent (n=10) and non–insulin-dependent diabetes mellitus (n=6). Patients with underlying inflammatory or malignant disease and those who smoked were not included in this study. The glycosylated fraction of the major component of adult hemoglobin (HbA1c) was elevated in all patients; this elevation ranged from 7.0% to 11.2%, with a median of 8.5% (25th and 75th percentiles, 7.9% and 9.3%, respectively). Healthy volunteers (n=14; 5 men and 9 women) were included in our study as a control group. Their mean age was 56.4±4.0 years. Informed consent was obtained from patients and healthy volunteers according to the requirements of the local ethical committee.
Isolation of Monocytes from Peripheral Venous
Blood
Monocytes were isolated from 60 mL of heparinized venous blood
samples using a slightly modified version of the method of Denholm and
Wolber.21 In brief, density centrifugation
was performed using the Ficoll separation solution with a
density of 1.077 g/mL (Biochrom) to isolate mononuclear cells. In a
second round of centrifugation, monocytes were enriched
using Percoll separation solution with a density of 1.139
g/mL (Sigma) before washing and resuspending the cells in DMEM
(Biochrom). The purity of the extracted monocytes was up to 93%, as
determined by analysis with a
fluorescence-activated cell sorter using an
antibody recognizing CD14 (M14-FITC, Coulter Electronics). The vitality
of the isolated monocytes was assessed by trypan blue exclusion; it was
always >90%.
Monocyte Migration
Monocyte chemotaxis was quantitated using a modified 48-well
Boyden chamber (Nuclepore) and polycarbonate membranes with a pore
diameter of 5 µm (Nuclepore). Monocytes were seeded in a
concentration of 5x105 cells/mL in DMEM and
allowed to migrate for a total of 3 hours in the humidified incubator
(37°C; 5% CO2). Adherent cells on the filter
membrane were fixed in 99% ethanol for 10 minutes and stained using
Giemsa dye before scraping off cells at the upper side of the filter
membrane. For a quantitative assessment of migrated cells, a total of
15 high power fields from 3 different wells (5 each) were counted. Cell
migration was stimulated with either VEGF-A165
(0.1 to 10 ng/mL; this was kindly provided by Denis Gospodarowicz,
Chiron, Emeryville, Calif) or formylMetLeuPhe (fMLP,
10-8 mol/L; Sigma).
Immunoprecipitation and In Vitro Kinase Assay
Isolated monocytes were preincubated for 5 minutes with 100
µmol/L Na3VO4 to inhibit
phosphatase activity. Cells were stimulated for 3 minutes at 37°C
with 50 ng/mL VEGF. After washing with ice-cold PBS containing 100
µmol/L Na3VO4, cells were
solubilized in a lysis buffer (150 mmol/L NaCl, 20 mmol/L
Tris-HCl [pH 7.4], 1% CHAPS [Sigma], 10 mmol/L EDTA, 10%
glycerol, 100 µmol/L
Na3VO4, 1% Trasylol
[Bayer], and 1 mmol/L PMSF). The cell lysates were
centrifuged at 10 000g for 15 minutes, and
phosphotyrosine-specific immunoprecipitation was performed using the
4G10 monoclonal antibody (UBI) and a rabbit anti-mouse antiserum
(Sigma). Immunoprecipitates immobilized on Protein
A-Sepharose CL 4B (Pharmacia) were used for the immune complex kinase
assay, which was performed for 7 minutes at room temperature in 25 µL
of 50 mmol/L HEPES buffer (pH 7.4) containing 10 mmol/L
MnCl2, 1 mmol/L dithiothreitol, and 5 µCi
of [
-32P]ATP (Amersham). The samples were
separated by SDS-PAGE (5 to 15% gradient) before the gels were
incubated for 30 minutes in 2.5% glutaraldehyde,
washed 2 times for 15 minutes in 10% acetic acid and 40% methanol,
treated for 1 hour at 55°C in 1 mol/L KOH to remove serine-bound
phosphate,22 washed 3 times for 20 minutes in 10%
acetic acid/40% methanol, dried, and exposed to Hyperfilm MP
(Amersham). Radioactive bands were quantitated on a Fuji
Phosphorimager.
Immunoradiometric Assay
The VEGF-A concentration was analyzed in serum samples
of all diabetic and nondiabetic subjects. Samples were stored at
-20°C until analysis. An immunoradiometric assay was
performed with 2 monoclonal antibodies specific for VEGF-A, which were
generously supplied by Genentech Inc (South San Francisco,
Calif). We used the monoclonal antibody B2.6.2 to recognize
VEGF-A165 and VEGF-A189 and
the monoclonal antibody A4.6.1 to recognize VEGF-A121,
VEGF-A165, and VEGF-A189.23 The
96-well plates (Maxisorp, Nunc) were coated with B2.6.2 (5 µg/mL) in
50 mmol/L carbonate buffer (pH 9.6) for 16 hours at 4°C. After
washing with 0.03% Tween 80 in PBS (pH 7.4), the plates were blocked
for 1 hour at 25°C using PBS (pH 7.4) with 0.5% bovine serum
albumin and 0.03% Tween 80. Plates were washed before
the addition of serum samples or the VEGF-A165
control (range, 5 pg/mL to 11 ng/mL) and incubated for 2 hours at
25°C; all experiments were performed in triplicate. After a washing
step, the monoclonal anti-VEGF antibody A4.6.1,
[125I]-labeled using the Chloramin-T
method,24 was added to each well
(5x104 cpm/well) and incubated for 2 hours at
25°C. Supernatants were then discarded, the plates were washed, and
the wells were counted using an automated -counter (LKB Wallac 1277
Gammamaster, LKB-Pharmacia). The sensitivity of the assay was 20 pg/mL.
No cross-reactivity was found with the closely related
platelet-derived growth factor-BB.
Statistical Analysis
Results of the migration assays and the VEGF-A serum levels were
analyzed using a 2-sided exact Wilcoxon test for
unpaired samples. Data for each group of patients were described as
medians and quartiles (25th and 75th percentiles). In the case of the
migration assay, testing was primarily performed for a VEGF-A
concentration of 1 ng/mL.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
VEGF-A–induced monocyte migration was assessed using a modified Boyden chamber assay. The migration of monocytes from healthy volunteers (n=14; age, 56.4±4.0 years) could be significantly stimulated with VEGF-A to 148.4% (25th and 75th percentiles, 136% and 170%) compared with the 100% baseline control value. This value was reached at 1.0 ng/mL VEGF-A (Figure 1A
).
For a VEGF-A concentration of 0.3 ng/mL, the maximal stimulatory effect
was slightly higher, with a median of 153.0% above the unstimulated
baseline, but no statistically significant difference was found between
this and the value obtained for a VEGF-A concentration of 1.0 ng/mL.
Monocytes from diabetic patients (n=16; age, 68.3±10.4 years;
HbA1c, 7.0% to 11.2%) could not be stimulated with VEGF-A
in this assay. This was true for all VEGF-A concentrations tested (0.1
to 10 ng/mL). Compared with the unstimulated 100% control,
VEGF-A–stimulated (1.0 ng/mL) monocyte migration measured 91.1% (25th
and 75th percentiles, 83% and 98%). When monocytes were stimulated
with VEGF-A at 0.1 ng/mL, this value measured 91.1% (25th and 75th
percentiles, 87% and 99%); it measured 91.8% (25th and 75th
percentiles, 82% and 100%) at 0.3 ng/mL VEGF-A and 87% (25th and
75th percentiles, 76% and 97%) at 10 ng/mL VEGF-A. All these values
were significantly below the results obtained for healthy individuals
(P<0.0001). No differences existed between monocytes
from patients with insulin-dependent and non–insulin-dependent
diabetes mellitus.
|
To clarify whether the migration of monocytes across the porous filter
membranes depended on the presence of a VEGF-A gradient between the
lower and the upper compartment, we performed a checkerboard
analysis. As shown in the
Table, the maximal induction of migration
occurred in the presence of a positive concentration gradient between
the 2 compartments. In the presence of equal concentrations of VEGF-A,
no enhanced migratory response could be observed. These results
indicate that VEGF-A can activate a true chemotactic response
in monocytes with no appreciable chemokinetic activity.
|
In contrast to the VEGF-A–induced effects, the VEGF-independent
chemotactic response of monocytes to the tripeptide fMLP
(10-8 mol/L) remained intact in diabetic
patients at 235% (25th and 75th percentiles, 158% and 357%); the
control group had a response of 304% (25th and 75th percentiles, 262%
and 420%) (Figure 1B
). No statistically
significant difference existed between the 2 groups.
The VEGF-A–inducible kinase activity of Flt-1 remained fully intact in
monocytes from diabetic patients, as assessed by the in vitro kinase
assay (Figure 2). VEGF-A could induce
similar levels of tyrosine phosphorylation in all
monocyte preparations analyzed. No differences existed in
monocytes isolated from healthy control subjects.
|
The VEGF-A serum level was measured in blood samples from all
individuals tested. The median VEGF-A serum level in healthy
individuals was 98 pg/mL (25th and 75th percentiles, 75 and 137 pg/mL).
In contrast, the VEGF-A serum levels of diabetic patients were
significantly elevated (median, 153 pg/mL; 25th and 75th percentiles,
106 and 230 pg/mL; P=0.0088) (Figure 3). VEGF-A serum levels of female
diabetics were higher than those of male diabetics (230 versus 149
pg/mL; P=NS), just as VEGF-A serum levels in healthy female
individuals were higher than those in healthy male individuals (116.5
versus 88 pg/mL; P=NS).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
In the present study, we showed for the first time that the cellular response to the angiogenic factor VEGF-A strongly depends on the integrity of the studied cells. Although the Flt-1–mediated chemotactic response to VEGF-A was strong and consistent in all monocytes isolated from healthy volunteers, monocytes from patients with diabetes mellitus did not properly respond, and they lacked the ability to migrate toward VEGF-A in a chemotaxis assay. Moreover, our data on the VEGF-A–induced and Flt-1–mediated signal transduction defect in diabetic patients provide novel insight into the mechanism of how monocyte function is impaired in diabetic patients.
The recruitment of monocytes is thought be an important step during collateral formation secondary to regional myocardial ischemia.20 25 Increased shear stress in preformed epicardial collaterals somewhat distant to the actual area of hypoxia and ischemia paves the way for monocyte accumulation, their maturation to macrophages, and the release of growth factors, which creates an inflammatory environment. In contrast to true angiogenesis, the process of arteriogenesis, which describes the growth of collateral vessels,17 seems to be critically dependent on monocytes and on proper monocyte function.20 25 Therefore, our ex vivo assay using the VEGF-A stimulation of monocytes may have a predictive value for a patient’s ability to develop collateral circulation to an ischemic area in the heart or in the peripheral circulation. In fact, during the initial review process of this article, a study was published in Circulation demonstrating that the ability of diabetic patients with coronary artery disease to develop coronary collaterals is significantly impaired.26 These data are compatible with our hypothesis of growth factor–induced monocyte migration as a predictor of an individual’s ability to develop collateral circulation. Therefore, our novel ex vivo assay is a good candidate for a surrogate assay of the process of arteriogenesis. Likewise, our data may serve as a molecular explanation for the reduced collateralization seen in diabetic patients.
Because VEGF-dependent monocyte function is severely reduced in monocytes from diabetic patients, our data suggest that VEGF-A and its receptor Flt-1 might indeed be critically involved in stimulating the process of arteriogenesis. VEGF-A could stimulate arteriogenesis in the following 2 different and independent ways. (1) Direct VEGF-A action stimulates the endothelium and promotes vascular remodeling. (2) VEGF-A promotes an indirect mode of activation by stimulating monocyte recruitment to the vessel wall. These monocytes and developing macrophages are vehicles for a number of vascular growth factors that are produced by these cells and released at the site of activation, such as vascular growth factors (including VEGF-A),27 28 basic fibroblast growth factor, transforming growth factor-ß, and epidermal growth factor.29
Our model, however, does not exclude the functional involvement of other growth factors and cytokines in the process of arteriogenesis. For example, monocytes could be recruited to the vessel wall by monocyte chemoattractant protein-1.19 On the basis of recent data, this protein could also act as a molecular mediator (it can be induced by VEGF-A).30 Because of the limited number of monocytes obtained from each preparation and the need for triplicate analysis and the inclusion of proper controls, we have not been able to test the response of monocytes from diabetic individuals toward other factors. However, this will be the subject of a future study.
In diabetic patients, the decreased chemotactic response of monocytes to VEGF-A is a consequence of impaired VEGF-A–induced and Flt-1–mediated signal transduction. Although the activation of tyrosine phosphorylation seems to remain fully intact, the signal does not reach the (intact) cytoskeletal components responsible for migration. Strong evidence indicates that the impaired VEGF-A–induced and Flt-1–mediated effect is selective and that the investigated monocytes are basically intact; for example, the potent and unspecific tripeptide fMLP can stimulate a proper chemotactic response in these cells. Therefore, our findings suggest a signal transduction defect is responsible for the impaired monocyte migration.
It is presently unclear whether the impaired VEGF-A–induced response of monocytes reflects or predicts an impaired endothelial response to VEGF-A. It may well be that the Flt-1–mediated response of VEGF-A in the endothelial cells of diabetic individuals is impaired as well. However, because most of the VEGF-A–induced responses in the endothelium are mediated by KDR11 and because KDR is not expressed in monocytes,18 our finding of impaired monocyte migration in diabetic individuals does not necessarily predict an impaired endothelial response to VEGF-A. There are many possible explanations for why arteriogenesis might be impaired while angiogenesis, in particular diabetic retinopathy, is stimulated in these patients. Although Flt-1–mediated responses are impaired in patients with diabetes mellitus, which leads to reduced monocyte migration and impaired arteriogenesis (as shown in this article), the angiogenic response of endothelial cells may be enhanced secondary to elevated VEGF-A levels. Another possible explanation might be a different degree of involvement of monocytes in arteriogenesis and angiogenesis. It is tempting to speculate that monocyte migration is the rate-limiting step in arteriogenesis, whereas the involvement of monocytes at sites of angiogenesis reflects the inflammatory nature of this process.
In the present study, we showed that the serum level of VEGF-A is significantly elevated in diabetic patients; this is similar to discoveries in the ocular fluid of patients with proliferative diabetic retinopathy.31 VEGF-A levels are raised under diabetic circumstances as a direct consequence of elevated glucose concentrations.32 In addition, the fact that angiogenesis is promoted in the form of diabetic retinopathy raises questions about differences in the pathogenesis of diabetic retinopathy and other forms of angiogenesis. Proliferative diabetic retinopathy is preceded by a long period of microvascular damage. After decades of chronic changes, microvascular occlusion eventually results in ischemia, which leads to the secretion of VEGF-A from the retina and to the development of abnormal angiogenesis within the isolated compartment of the eye. It is conceivable that elevated VEGF-A levels in diabetic individuals acting on KDR may compensate for the impaired activity of any Flt-1–mediated cellular response.
Taken together, these data indicate that the cellular response of monocytes to VEGF-A is attenuated in diabetic patients due to a downstream signal transduction defect. Therefore, we postulate that the VEGF-A–induced and monocyte-dependent process of collateral formation is severely impaired in diabetic patients and that VEGF-A–based therapeutic strategies to enhance tissue perfusion should give better results in patients not suffering from diabetes mellitus.
|
Acknowledgments |
|---|
This study was supported in part by grants Wa734/2-1 and Wa734/2-4 from the Deutsche Forschungsgemeinschaft and by the Sonderforschungsbereich SFB451, project B1 (all to J.W.). We would like to acknowledge the kind gift of recombinant VEGF-A from Denis Gospodarowicz, Chiron, Emeryville, Calif. We thank Hedwig Frank for performing the checkerboard analysis.
Received October 29, 1999; revision received February 2, 2000; accepted February 9, 2000.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1. Carmeliet P, Ferreira V, Breier G, et al. Abnormal blood vessel development and lethality in embryos lacking a single VEGF allele. Nature. 1996;380:435–439.[Medline] [Order article via Infotrieve]
2. Ferrara N, Carver-Moore K, Chen H, et al. Heterozygous embryonic lethality induced by targeted inactivation of the VEGF gene. Nature. 1996;380:439–442.[Medline] [Order article via Infotrieve]
3. Fong G-H, Rossant J, Gertsenstein M, et al. Role of the Flt-1 receptor tyrosine kinase in regulating the assembly of vascular endothelium. Nature. 1995;376:66–70.[Medline] [Order article via Infotrieve]
4. Shalaby F, Rossant J, Yamaguchi TP, et al. Failure of blood-island formation and vasculogenesis in Flk-1-deficient mice. Nature. 1995;376:62–66.[Medline] [Order article via Infotrieve]
5.
Banai S, Jaklitsch MT, Shou M, et al.
Angiogenic-induced enhancement of collateral blood flow to
ischemic myocardium by vascular
endothelial growth factor in dogs.
Circulation. 1994;89:2183–2189.
6.
Waltenberger J. Modulation of growth factor action:
implications for the treatment of cardiovascular
diseases. Circulation. 1997;96:4083–4095.
7.
Baumgartner I, Pieczek A, Manor O, et al. Constitutive
expression of phVEGF165 after intramuscular gene
transfer promotes collateral vessel development in patients with
critical limb ischemia. Circulation. 1998;97:1114–1123.
8.
Folkman J. Angiogenic therapy of the human heart.
Circulation. 1998;97:628–629.
9. Waltenberger J. Therapeutic angiogenesis in the heart using peptide growth factors: Angiogenesis research entering clinical trials. Angiogenesis. 1998;2:115–117.
10. Feener EP, King GL. Vascular dysfunction in diabetes mellitus. Lancet. 1997;350:9–13.
11.
Waltenberger J, Claesson-Welsh L, Siegbahn A, et al.
Different signal transduction properties of KDR and
Flt1, two receptors for vascular endothelial
growth factor. J Biol Chem. 1994;269:26988–26995.
12.
Asahara T, Bauters C, Pastore C, et al. Local delivery
of vascular endothelial growth factor accelerates
reendothelialization and attenuates intimal hyperplasia
in balloon-injured rat carotid artery. Circulation. 1995;91:2793–2801.
13. Folkman J. Angiogenesis in cancer, vascular, rheumatoid and other disease. Nat Med. 1995;1:27–31.[Medline] [Order article via Infotrieve]
14.
Höckel M, Burke FJ. Angiotropin treatment
prevents flap necrosis and enhances dermal regeneration in rabbits.
Arch Surg. 1989;124:693–698.
15.
Rosengart TK, Lee LY, Patel SR, et al. Angiogenesis
gene therapy: phase I assessment of direct intramyocardial
administration of an adenovirus vector expressing VEGF121 cDNA to
individuals with clinically significant severe coronary artery
disease. Circulation. 1999;100:468–474.
16.
Losordo DW, Vale PR, Symes JF, et al. Gene therapy for
myocardial angiogenesis: initial clinical results with direct
myocardial injection of phVEGF(165) as sole therapy for myocardial
ischemia. Circulation. 1998;98:2800–2804.
17.
Schaper W, Buschmann I. Collateral circulation and
diabetes. Circulation. 1999;99:2224–2226. Editorial.
18.
Clauss M, Weich H, Breier G, et al. The vascular
endothelial growth factor receptor FLT-1 mediates
biological activities: implications for a functional role of placenta
growth factor in monocyte activation and chemotaxis. J Biol
Chem. 1996;271:17629–17634.
19.
Ito WD, Arras M, Winkler B, et al. Monocyte chemotactic
protein-1 increases collateral and peripheral conductance
after femoral artery occlusion. Circ Res. 1997;80:829–837.
20. Arras M, Ito WD, Scholz D, et al. Monocyte activation in angiogenesis and collateral growth in the rabbit hindlimb. J Clin Invest. 1998;101:40–50.[Medline] [Order article via Infotrieve]
21. Denholm EM, Wolber FM. A simple method for the purification of human peripheral blood monocytes. J Immunol Methods. 1991;144:247–251.[Medline] [Order article via Infotrieve]
22.
Cooper JA, Hunter T. Changes in protein
phosphorylation in rous sarcoma virus-transformed
chicken embryo cells. Mol Cell Biol. 1981;1:165–178.
23. Kim KJ, Li B, Winer J, et al. Inhibition of vascular endothelial growth factor-induced angiogenesis suppresses tumour growth in vivo. Nature.. 1993;362:841–844.[Medline] [Order article via Infotrieve]
24. Hunter WM, Greenwood FC. Preparation of iodine131 labelled human growth hormone of high specific activity. Nature. 1962;194:495–496.[Medline] [Order article via Infotrieve]
25. Schaper W. Coronary collateral development: concepts and hypotheses. In: Schaper W, Schaper J, eds. Collateral Circulation: Heart, Brain, Kidney, Limbs. Boston: Kluwer Academic Publishers; 1993:41–64.
26.
Abaci A, Oguzhan A, Kahraman S, et al. Effect of
diabetes mellitus on formation of coronary collateral
vessels. Circulation. 1999;99:2239–2242.
27. Berse B, Brown LF, van de Water L, et al. Vascular permeability factor (vascular endothelial growth factor) gene is expressed differentially in normal tissues, macrophages, and tumors. Mol Biol Cell. 1992;3:211–220.[Abstract]
28. Iijima K, Yoshikawa N, Connolly D, et al. Human mesangial cells and peripheral blood mononuclear cells produce vascular permeability factor. Kidney Int. 1993;44:959–966.[Medline] [Order article via Infotrieve]
29. Ross R. The pathogenesis of atherosclerosis: a perspective for the 1990s. Nature. 1993;362:801–809.[Medline] [Order article via Infotrieve]
30.
Marumo T, Schini-Kerth VB, Busse R. Vascular
endothelial growth factor activates nuclear
factor-
B and induces monocyte chemoattractant protein-1 in
bovine retinal endothelial cells. Diabetes. 1999;48:1131–1137.[Abstract]
31.
Aiello LP, Avery RL, Arrigg PG, et al. Vascular
endothelial growth factor in ocular fluid of patients
with diabetic retinopathy and other retinal disorders.
N Engl J Med. 1994;331:1480–1487.
32. Natarajan R, Bei W, Lanting L, et al. Effects of high glucose on vascular endothelial growth factor expression in vascular smooth muscle cells. Am J Physiol. 1997;273:H2224–H2231.
This article has been cited by other articles:
 |
|
 |
|
  J. Waltenberger Limits to Growth of Native Collateral Vessels: Just One Mouse CLIC Away From Unlimited Collateral Perfusion? Circ. Res., July 2, 2009; 105(1): 9 - 11. [Full Text] [PDF]
|
|
|
|
 |
|
 F. Mouquet, F. Cuilleret, S. Susen, K. Sautiere, P. Marboeuf, P. V. Ennezat, E. McFadden, P. Pigny, F. Richard, B. Hennache, et al. Metabolic syndrome and collateral vessel formation in patients with documented occluded coronary arteries: association with hyperglycaemia, insulin-resistance, adiponectin and plasminogen activator inhibitor-1 Eur. Heart J., April 1, 2009; 30(7): 840 - 849. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Zampetaki and Q. Xu Vascular Remodeling in Diabetes: Don't Leave Without Your STAT5 Arterioscler. Thromb. Vasc. Biol., January 1, 2009; 29(1): 10 - 11. [Full Text] [PDF]
|
|
|
|
 |
|
 J. M. van Golde, M. S. Ruiter, N. C. Schaper, S. Voo, J. Waltenberger, W. H. Backes, M. J. Post, and M. S. Huijberts Impaired Collateral Recruitment and Outward Remodeling in Experimental Diabetes Diabetes, October 1, 2008; 57(10): 2818 - 2823. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Kerber, Y. Reiss, A. Wickersheim, M. Jugold, F. Kiessling, M. Heil, V. Tchaikovski, J. Waltenberger, M. Shibuya, K. H. Plate, et al. Flt-1 Signaling in Macrophages Promotes Glioma Growth In vivo Cancer Res., September 15, 2008; 68(18): 7342 - 7351. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. S. Czepluch and J. Waltenberger Vascular endothelial growth factor protein levels and gene expression in peripheral monocytes after stenting: a randomized comparative study of sirolimus-eluting and bare-metal stents Eur. Heart J., August 1, 2008; 29(15): 1924 - 1925. [Full Text] [PDF]
|
|
|
|
|
|
S. Dimmeler and A. Leri Aging and Disease as Modifiers of Efficacy of Cell Therapy Circ. Res., June 6, 2008; 102(11): 1319 - 1330. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Kinnaird, E. Stabile, S. Zbinden, M.-S. Burnett, and S. E. Epstein Cardiovascular risk factors impair native collateral development and may impair efficacy of therapeutic interventions Cardiovasc Res, May 1, 2008; 78(2): 257 - 264. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Spinetti, N. Kraenkel, C. Emanueli, and P. Madeddu Diabetes and vessel wall remodelling: from mechanistic insights to regenerative therapies Cardiovasc Res, May 1, 2008; 78(2): 265 - 273. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Tchaikovski, G. Fellbrich, and J. Waltenberger The Molecular Basis of VEGFR-1 Signal Transduction Pathways in Primary Human Monocytes Arterioscler. Thromb. Vasc. Biol., February 1, 2008; 28(2): 322 - 328. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Stadler, J. Eggermann, S. Voo, A. Kranz, and J. Waltenberger Smoking-Induced Monocyte Dysfunction Is Reversed by Vitamin C Supplementation In Vivo Arterioscler. Thromb. Vasc. Biol., January 1, 2007; 27(1): 120 - 126. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. de Paulis, N. Prevete, I. Fiorentino, F. W. Rossi, S. Staibano, N. Montuori, P. Ragno, A. Longobardi, B. Liccardo, A. Genovese, et al. Expression and Functions of the Vascular Endothelial Growth Factors and Their Receptors in Human Basophils J. Immunol., November 15, 2006; 177(10): 7322 - 7331. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. G Ebrahimian, C. Heymes, D. You, O. Blanc-Brude, B. Mees, L. Waeckel, M. Duriez, J. Vilar, R. P. Brandes, B. I. Levy, et al. NADPH Oxidase-Derived Overproduction of Reactive Oxygen Species Impairs Postischemic Neovascularization in Mice with Type 1 Diabetes Am. J. Pathol., August 1, 2006; 169(2): 719 - 728. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J.-S. Silvestre and B. I. Levy Molecular Basis of Angiopathy in Diabetes Mellitus Circ. Res., January 6, 2006; 98(1): 4 - 6. [Full Text] [PDF]
|
|
|
|
 |
|
 R Zbinden, S Zbinden, M Billinger, S Windecker, B Meier, and C Seiler Influence of diabetes mellitus on coronary collateral flow: an answer to an old controversy Heart, October 1, 2005; 91(10): 1289 - 1293. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Simons Angiogenesis, Arteriogenesis, and Diabetes: Paradigm Reassessed? J. Am. Coll. Cardiol., September 6, 2005; 46(5): 835 - 837. [Full Text] [PDF]
|
|
|
|
 |
|
 M. Simons Angiogenesis: Where Do We Stand Now? Circulation, March 29, 2005; 111(12): 1556 - 1566. [Full Text] [PDF]
|
|
|
|
|
|
J. Waltenberger Growth factor signal transduction defects in the cardiovascular system Cardiovasc Res, February 15, 2005; 65(3): 574 - 580. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. E. Markkanen, T. T. Rissanen, A. Kivela, and S. Yla-Herttuala Growth factor-induced therapeutic angiogenesis and arteriogenesis in the heart-gene therapy Cardiovasc Res, February 15, 2005; 65(3): 656 - 664. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. M. Dikov, J. E. Ohm, N. Ray, E. E. Tchekneva, J. Burlison, D. Moghanaki, S. Nadaf, and D. P. Carbone Differential Roles of Vascular Endothelial Growth Factor Receptors 1 and 2 in Dendritic Cell Differentiation J. Immunol., January 1, 2005; 174(1): 215 - 222. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. G. Ebrahimian, R. Tamarat, M. Clergue, M. Duriez, B. I. Levy, and J.-S. Silvestre Dual Effect of Angiotensin-Converting Enzyme Inhibition on Angiogenesis in Type 1 Diabetic Mice Arterioscler. Thromb. Vasc. Biol., January 1, 2005; 25(1): 65 - 70. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. L. Unthank, K. M. Sheridan, and M. C. Dalsing Collateral Growth in the Peripheral Circulation: A Review Vascular and Endovascular Surgery, July 1, 2004; 38(4): 291 - 313. [Abstract] [PDF]
|
|
|
|
|
|
P. D. Lambiase, R. J. Edwards, P. Anthopoulos, S. Rahman, Y. G. Meng, C. A. Bucknall, S. R. Redwood, J. D. Pearson, and M. S. Marber Circulating Humoral Factors and Endothelial Progenitor Cells in Patients With Differing Coronary Collateral Support Circulation, June 22, 2004; 109(24): 2986 - 2992. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M Fujita and K Tambara Recent insights into human coronary collateral development Heart, March 1, 2004; 90(3): 246 - 250. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Tamarat, J.-S. Silvestre, S. Le Ricousse-Roussanne, V. Barateau, L. Lecomte-Raclet, M. Clergue, M. Duriez, G. Tobelem, and B. I. Levy Impairment in Ischemia-Induced Neovascularization in Diabetes: Bone Marrow Mononuclear Cell Dysfunction and Therapeutic Potential of Placenta Growth Factor Treatment Am. J. Pathol., February 1, 2004; 164(2): 457 - 466. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. K. Selvaraj, R. K. Giri, N. Perelman, C. Johnson, P. Malik, and V. K. Kalra Mechanism of monocyte activation and expression of proinflammatory cytochemokines by placenta growth factor Blood, August 15, 2003; 102(4): 1515 - 1524. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Tamarat, J.-S. Silvestre, M. Huijberts, J. Benessiano, T. G. Ebrahimian, M. Duriez, M.-P. Wautier, J. L. Wautier, and B. I. Levy Blockade of advanced glycation end-product formation restores ischemia-induced angiogenesis in diabetic mice PNAS, July 8, 2003; 100(14): 8555 - 8560. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Rehman, J. Li, C. M. Orschell, and K. L. March Peripheral Blood "Endothelial Progenitor Cells" Are Derived From Monocyte/Macrophages and Secrete Angiogenic Growth Factors Circulation, March 4, 2003; 107(8): 1164 - 1169. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Heeschen, M. Weis, and J. P. Cooke Nicotine promotes arteriogenesis J. Am. Coll. Cardiol., February 5, 2003; 41(3): 489 - 496. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. M. Tepper, R. D. Galiano, J. M. Capla, C. Kalka, P. J. Gagne, G. R. Jacobowitz, J. P. Levine, and G. C. Gurtner Human Endothelial Progenitor Cells From Type II Diabetics Exhibit Impaired Proliferation, Adhesion, and Incorporation Into Vascular Structures Circulation, November 26, 2002; 106(22): 2781 - 2786. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Krabatsch, R. Petzina, H. Hausmann, A. Koster, and R. Hetzer Factors influencing results and outcome after transmyocardial laser revascularization Ann. Thorac. Surg., June 1, 2002; 73(6): 1888 - 1892. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Edelberg, L. Tang, K. Hattori, D. Lyden, and S. Rafii Young Adult Bone Marrow-Derived Endothelial Precursor Cells Restore Aging-Impaired Cardiac Angiogenic Function Circ. Res., May 31, 2002; 90 (10): e89 - e93. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Pohl, C. Seiler, M. Billinger, E. Herren, K. Wustmann, H. Mehta, S. Windecker, F. R. Eberli, and B. Meier Frequency distribution of collateral flow and factors influencing collateral channel development: Functional collateral channel measurement in 450 patients with coronary artery disease J. Am. Coll. Cardiol., December 1, 2001; 38(7): 1872 - 1878. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Harraz, C. Jiao, H. D. Hanlon, R. S. Hartley, and G. C. Schatteman CD34- Blood-Derived Human Endothelial Cell Progenitors Stem Cells, July 1, 2001; 19(4): 304 - 312. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Jelkmann Pitfalls in the Measurement of Circulating Vascular Endothelial Growth Factor Clin. Chem., April 1, 2001; 47(4): 617 - 623. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Waltenberger Impaired collateral vessel development in diabetes: potential cellular mechanisms and therapeutic implications Cardiovasc Res, February 16, 2001; 49(3): 554 - 560. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||