Serum Vascular Endothelial Growth factor-A Levels Research Articles

374P - Vegf-A Level As a Predictor of Bevacizumab Benefit for Breast Cancer: Systematic Review with Meta-Analysis

ABSTRACT Aim: Bevacizumab lacks any potential biomarker of benefit, precluding its optimal use for breast cancer therapy. Among the putative candidates, the serum levels of vascular endothelial growth factor-A (VEGF-A) - a target of bevacizumab - has recently called attention as a promising marker. We sought to evaluate the role of VEGF-A levels as a biomarker. Methods: We searched electronic databases and meeting proceeding for randomised controlled trials (RCTs) comparing the addition of bevacizumab to standard chemotherapy. RCTs were included if outcomes of high and low VEGF-A serum breast cancer patients were presented. Random-effects model were applied to calculate the pooled hazard ratios for event-free survival (EFS), comprising disease recurrence, progression or any-cause death, and overall survival (OS), with respective confidence intervals (95% CI). High and low VEGF-A levels subgroups followed each trial definition, and results were compared using interaction test. Heterogeneity was calculated using Chi-squared test (I2). Results: Three trials enrolled a total of 3748 patients, with 1713 patients with VEGF-A serum available for assessment, were included. One trial added bevacizumab in adjuvant setting (N = 2591, 1155 for biomarker evaluation) and two as first-line therapy (N = 1157, 558 for biomarker evaluation). Bevacizumab improved EFS of patients with above median VEGF-A serum levels (HR: 0.62; 95% CI 0.49–0.79; P Conclusions: The need for a marker of benefit of this expensive therapy medication is an unmet need and better patient selection can improve outcomes and resource use. Serum VEGF-A levels may be a promising marker of bevacizumab activity in breast cancer, either in palliative or adjuvant scenario and further assessment of bevacizumab use in breast cancer should focus on VEGF-A measurement Disclosure: All authors have declared no conflicts of interest.

Serum vascular endothelial growth factor-A (VEGF-A) as a biomarker in squamous cell carcinoma of head and neck patients undergoing chemoradiotherapy.

To evaluate serum VEGF-A levels in squamous cell carcinoma of head and neck (SCCHN) patients and relationships with response to therapy. Serum VEGF-A levels in patients (n=72) treated with radiotherapy (RT) or radio-chemotherapy (RCT) and controls (n=40) were measured by ELISA. Serum VEGF-A levels of the SCCHN cases were significantly higher (p=0.001) than in healthy controls, and in patients with positive as compared to negative lymph node status (p=0.004). Similarly, patients with advanced stage (Stage III-IV) disease had more greatly elevated levels of serum VEGF-A level than their early stage (Stage I-II) counterparts (p=0.001). In contrast, there was no significant difference (p=0.57) in serum level of VEGF-A in patients with advanced T-stage (T3-4) as compared to early stage (T1-2). Similarly, patients with distant metastasis had no significant (p=0.067) elevation in serum VEGF-A level as compared to non-metastatic disease. However, the non-responder patients had significantly higher serum VEGF-A level as compared to responders (p=0.001). Our results suggest that the serum VEGF-A level may be a useful biomarker for the prediction of response to therapy in SCCHN.

Serum tissue inhibitor of metalloproteinase 1 (TIMP-1) and vascular endothelial growth factor A (VEGF-A) are associated with prognosis in esophageal cancer patients

The matrix metalloproteinases, tissue inhibitors of metalloproteinases and angiogenesis contribute to growth and spread of cancer. We investigated the correlation between pretreatment serum levels of tissue inhibitor of metalloproteinase 1 (TIMP-1) and vascular endothelial growth factor A (VEGF-A), and clinicopathologic features and survival in patients with esophageal cancer (EC). Serum TIMP-1 and VEGF-A were measured by enzyme-linked immunosorbent assay (ELISA) in 89 patients with EC, and 30 healthy controls. Serum TIMP-1 and VEGF-A levels were significantly higher in patients with esophageal carcinoma than in the control group (p=0.001 and p<0.001, respectively). High levels of TIMP-1 were associated with histological type (p<0.001), tumor depth (p<0.001), stage (p<0.001) and lymph node metastases (p=0.001). Subgroup analysis showed that tumor size (p<0.001), tumor depth (p<0.001), stage (p<0.001), lymph node metastases (p=0.002), distant metastases (p=0.009) and resectability (p=0.003), were correlated with an elevated level of VEGF-A. Patients with elevated levels of TIMP-1 and VEGF-A had a significantly lower overall survival (p=0.02 and p=0.048, respectively), and disease-free survival (TIMP-1, p<0.001). High serum levels of TIMP-1 and VEGF-A were found to be associated with tumor progression and unfavorable prognosis in patients with EC.

Comparison of the diagnostic values of circulating steroid hormones, VEGF-A, PIGF, and ADAM12 in women with ectopic pregnancy

BackgroundSeveral peripheral proteins that might be useful for detecting the presence of ectopic pregnancy (EP) have been evaluated, but none have been proven entirely useful in the clinic. We investigated the presence and the possible changes in circulating molecules that distinguish between normal intrauterine pregnancy (IUP) and tubal ectopic pregnancy.MethodsNon-pregnant women during the menstrual cycle, women with IUP, and women with tubal EP after informed consent. Serum levels of 17β-estradiol (E2), progesterone (P4), testosterone (T), beta-human chorionic gonadotropin (β-hCG), vascular endothelial growth factor-A (VEGF-A), placental growth factor (PIGF), and a distintegrin and metalloprotease protein 12 (ADAM12) were analyzed. Receiver operating characteristic analysis was used to assess the diagnostic discrimination of EP and gestational age-matched IUP.ResultsE2, P4, PIGF, and ADAM12 levels increased and β-hCG decreased throughout IUP. E2 and VEGF-A levels were significantly different between women with tubal EP and IUP. However, using a serum β-hCG cut-off of less than 1000 mIU/mL, P4 was significantly lower in women with tubal EP compared to IUP. Although E2 was inversely correlated with VEGF-A in women in the early stages of IUP, E2 was not correlated with VEGF-A in women with EP prior to tubal surgery. There were no significant differences in either PIGF or ADAM12 alone between women with tubal EP or IUP. Although no significant correlations were seen between E2 and PIGF or P4 and ADAM12 in women in the early stages of IUP, E2 was positively correlated with PIGF and P4 was positively correlated with ADAM12 in women with EP prior to tubal surgery. Our studies defined associations but not causality.ConclusionsIndividual measurements of serum E2 or VEGF-A levels are strongly related to early pregnancy outcomes for women with IUP and EP, and pregnancy-associated E2 and VEGF-A levels provide diagnostic accuracy for the presence of tubal EP. This study demonstrates that correlation analysis of E2/VEGF-A and E2/PIGF serum levels may be able to distinguish a tubal EP from a normal IUP.

Association of low serum levels of transforming growth factor β1 (TGF-β1) and high levels of vascular endothelial growth factor-A (VEGF-A) following neoadjuvant chemoradiotherapy with poor outcome in esophageal cancer patients receiving combined modality therapy: A preliminary analysis using proximity ligation assay.

80 Background: Currently, serum biomarkers do not influence the treatment of esophageal cancer. The purpose of this project is to investigate, using the proximity ligation assay (PLA), serum biomarkers that predict treatment response and survival outcome for patients with locally advanced esophageal cancer (LAEC) undergoing neoadjuvant concurrent chemoradiotherapy (CCRT) followed by radical esophagectomy. Methods: From 2004 to 2011, 79 patients with LAEC receiving CCRT of taxane-based chemotherapy and 40 Gy followed by curative surgery were enrolled in this study. Serum samples were collected before and within one month after CCRT. Fifteen biomarkers (Axl, BMP2/4, EGFR, FAM84B, Gas6, Her2, IGFBP3, MMP1, MMP13, OPN, PDGFR-α, Periostin, SPARC, TGF-β1, VEGF-A) were analyzed using PLA. Pathological responses were classified into complete response (CR), microscopic residual (MicroR), or macroscopic residual (MacroR). Associations between serum level of each biomarker and pathological response, disease-free survival (DFS), and overall survival (OS) were evaluated by ANOVA and Log-rank tests. Results: Of 79 patients, 30 had CR (38%), 37 had MicroR (47%) and 12 had MacroR (15%). With a median follow-up of 54.5 months, the median OS and DFS were 34 and 43 months, respectively. Among evaluated biomarkers, TGF-β1 was the most significant one associated with pathological response (p=0.009, two-way ANOVA), with higher post-CCRT TGF-β1 levels predicting better response (p=0.035, one-way ANOVA). Patients with higher post-CCRT TGF-β1 levels (≥3rd quartile) had significantly better DFS (median not reached vs. 27 months, p=0.03). Patients with both lower levels of post-CCRT TGF-β1 and higher levels of VEGF-A had significantly worse DFS (13 months, p=0.001) and OS (18 months, p=0.035). Conclusions: Post-CCRT serum TGF-β1 and VEGF-A levels by PLA may be used to predict pathological response and survival outcome for esophageal cancer patients receiving combined modality therapy.

Association of Nerve Growth Factor and Vascular Endothelial Growth Factor A with Psychometric Measurements of Opiate Dependence: Results of a Pilot Study in Patients Participating in a Structured Diamorphine Maintenance Program

Preclinical study results suggest that neurotrophic peptides like nerve growth factor (NGF) and vascular endothelial growth factor A (VEGF-A) may be associated with symptoms of addictive behavior like withdrawal symptoms and rewarding effects. We investigated alterations in NGF and VEGF-A serum levels in opiate-dependent patients (25 male patients), who received diamorphine (DAM, heroin) treatment within a structured opiate maintenance program, and compared the results with the NGF and VEGF-A serum levels of healthy controls (23 male controls). NGF and VEGF-A serum levels were assessed before and after DAM administration twice a day (in the morning (16 h after last application – t1) and in the afternoon (7 h after last application – t3)) in order to detect a possible immediate or summative (in the afternoon) heroin effect on these two neuropeptides. Moreover, we investigated possible associations between the serum levels of these neurotrophic growth factors and psychometric dimensions of addictive behavior, e.g. craving, withdrawal, depression. Whereas there was no direct effect of DAM application on the serum levels of both neurotrophic growth factors neither in the morning nor in the afternoon, the NGF serum levels of the patient group were found to be significantly increased at all four time points of investigation compared with the healthy controls. In contrast, VEGF-A serum levels did not differ significantly in the patient and control groups. We found a significant positive association between the NGF serum levels and several items of the short opiate withdrawal scale as well as a negative association between self-reported mood (measured by visual analogue scale) and mood before heroin application (in the morning as in the afternoon). Moreover, we found a significant positive association between the NGF serum levels (t1 and t3) and the self-reported craving for methadone. In contrast, we found a negative association between the VEGF-A serum levels and avoidance, anxiety, suicide intentions of the SCL-90 as well as a positive association between the VEGF-A serum levels and the subscales of the heroin craving questionnaire measuring the rewarding effects of heroin. In conclusion, the results of this pilot study show that there might be an association between symptoms of opiate dependence and withdrawal and serum levels of VEGF-A and NGF.

VEGF-A immunohistochemical and mRNA expression in tissues and its serum levels in potentially malignant oral lesions and oral squamous cell carcinomas

The aim of the study was to investigate whether the estimation of circulating Vascular endothelial growth factor-A (VEGF-A) levels by ELISA could be used as surrogate of VEGF-A expression in tissues of pre-malignant oral lesions (PMOLs) and oral squamous cell carcinoma (OSCC) as compared to that in healthy controls. The study samples comprised of tissue and blood samples from 60 PMOLs, 60 OSCC, and 20 healthy controls. Serum VEGF-A levels were determined by an ELISA based assay (Quantikine human VEGF; R & D System, Minneapolis USA). Tissue VEGF-A expression and microvessel density (MVD) were assessed by immunohistochemistry (IHC) using antibodies against VEGF-A and CD-34 on formalin fixed paraffin embedded (FFPE) tissue sections. VEGF-A mRNA expression was analyzed by real-time PCR in snap frozen tissues. Serum VEGF-A levels and immunohistochemical VEGF-A expression were significantly high in PMOLs and OSCC in comparison with controls. VEGF mRNA gene expression showed more than 50-fold increase in PMOLs and OSCC. VEGF-A levels in serum correlated in a linear fashion with the tissue expression in oral pre-malignant and malignant lesions, suggesting that the serum levels may serve as surrogate material for tissue expression of VEGF-A.

Vascular endothelial growth factor-A and changes in a tumor-bearing mouse model with Lewis lung cancer

Vascular endothelial growth factor-A (VEGF-A) affects tumor growth and metastasis through stimulation of angiogenesis. The purpose of this study was to describe features of Lewis lung cancer (LLC) in mice and compare the serum VEGF-A levels with those of normal control mice. Two groups of mice were compared: one was subcutaneously injected with LLC cells (n=16) and the other served as the normal control (n=6). The serum VEGF-A levels were measured by ELISA prior to inoculation, and at 7, 21 and 35 days post-inoculation. The tumor weight and the metastatic condition were evaluated on day 35. Changes in body weight and serum VEGF-A concentration over a period of time were compared between the groups using generalized estimating equations. The relationship between the primary tumor and the metastatic condition was analyzed using the Spearman's rank correlation test. The survival rate was 56.3% on day 35 post-tumor inoculation. No difference was found between the groups with regard to gastrocnemius muscle weight on day 35 post-inoculation [0.1315±0.0066 g vs. 0.1308±0.0069 g (normal control)]. In tumor-bearing mice, the weight gain at sacrifice was less (0.24±0.45 vs. 1.93±0.47 g, P=0.01), the final mean tumor volume and weight were 4264.69±1038.32 mm(3) and 3.70±0.83 g, the number of nodules in the lungs and livers was 6.33 (range 0-20) and 2.22 (range 0-11), respectively, and the serum VEGF-A levels were significantly higher than those of control mice. In conclusion, lower body weight gain, metastasis in the liver and lungs, and elevated VEGF-A levels are features of LLC in mice.

Association of angiopoietin-2, C-reactive protein and markers of obesity and insulin resistance with survival outcome in colorectal cancer

Background:This study investigated the relationship of obesity, insulin resistance, inflammation and angiogenesis with cancer progression and survival in a colorectal cancer cohort.Methods:Clinical and pathological data, along with anthropometric and follow-up data, were collected from 344 consecutive colorectal cancer patients. Serum samples at diagnosis were analysed by immunoassay for adiponectin, C-reactive protein (CRP), vascular endothelial growth factor-A (VEGF-A), angiopoietin-2 (Ang-2), insulin-like growth factor-1 (IGF-1), insulin and C-peptide.Results:Serum Ang-2 and VEGF-A levels increased with tumour T stage (P=0.007 and P=0.025, respectively) and N stage (P=0.02 and P=0.03, respectively), and correlated with CRP levels (r=0.43, P<0.001 and r=0.23, P<0.001, respectively). Angiopoietin-2 correlated with C-peptide (r=0.14, P=0.007) and VEGF-A with IGF-1 in males (r=0.25, P=0.001). Kaplan–Meier analysis showed that patients with high serum levels of CRP and Ang-2 had significantly reduced survival (both P⩽0.001). After adjusting for tumour stage and age, Ang-2 remained a significant predictor of survival. The CRP levels were inversely associated with survival in American Joint Committee on Cancer stage II patients (P=0.038), suggesting that CRP could be used to support treatment decisions in this subgroup. Serum markers and anthropometric measures of obesity correlated with each other, but not with survival.Conclusion:Our study supports the concept that obesity-related inflammation, rather than obesity itself, is associated with colorectal cancer progression and survival. The study confirms serum Ang-2 as a predictive marker for outcome of colorectal cancer.

CLINICAL STUDY: BRIEF REPORT: Serum levels of vascular endothelial growth factor A increase during alcohol withdrawal

Vascular endothelial growth factor A (VEGF-A) is a key regulator of angiogenesis. This study investigated VEGF-A serum levels during alcohol withdrawal (days 1, 7 and 14, 76 male patients, 38 healthy controls). Patients showed significantly higher VEGF-A serum levels (t = 2.620, P = 0.010), which increased significantly during withdrawal (F = 4.484, P = 0.014, mean difference = -36.835, P = 0.037). The increase of VEGF-A serum levels was significantly associated with initial breath alcohol concentration and the sumscore of the severity scale of alcohol dependence (SESA questionnaire, F = 5.252, P = 0.008). Increase of VEGF-A serum levels is closely associated to alcohol intoxication and severity of alcohol dependence.

Evaluation of the association of serum levels of hyaluronic acid, sICAM-1, sVCAM-1, and VEGF-A with mortality and prognosis in patients with Crimean-Congo hemorrhagic fever

Background Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral hemorrhagic disease. Pathogenesis of the disease has not been well described yet. A well-known pathogenic feature of CCHF virus is its capability to damage endothelium. Increased hyaluronic acid (HA) levels indicate liver sinusoidal endothelial damage. Soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1) and vascular endothelial growth factor-A (VEGF-A) play a role in the inflammatory process, vascular damage and plasma leakage. Objectives To investigate whether or not there is a relationship between HA, sICAM-1, sVCAM-1 and VEGF-A serum levels and fatality in CCHF. Study design Sixty-one patients who were confirmed by RT-PCR and serological tests for CCHF, included in the current study. HA, sICAM-1, sVCAM-1, VEGF-A levels in serum samples were analyzed by ELISA. Results There were statistically significant differences between fatal and non-fatal CCHF patients in terms of HA, sICAM-1, sVCAM-1, and VEGF-A levels. In addition, AST and ALT levels were positively correlated with HA, sICAM-1, sVCAM-1, and VEGF-A levels. Conclusion HA, sICAM-1, sVCAM-1, and VEGF-A levels of the patients that died during hospitalization were statistically significantly higher than the patients that survived, and this finding suggests that the level of these molecules could be used as a prognostic marker in CCHF.

Signs of reduced angiogenic activity after surgical removal of deeply infiltrating endometriosis

To study the concentrations of vascular endothelial growth factor A (VEGF-A), soluble vascular endothelial growth factor receptors-1 and -2 (sVEGFR-1 and -2), angiogenin, and angiopoietin-2 (Ang-2) in serum and peritoneal fluid from healthy controls and women with advanced endometriosis. Further, we addressed the question of whether surgical removal of endometriotic lesions was associated with normalization of the serum concentrations of the same markers. Patients with endometriosis before and after surgery were compared with control patients. University Hospital. Twenty-one healthy controls and 32 women with advanced endometriosis. In women with endometriosis we performed surgical removal of endometriotic lesions using laparoscopy. Data on serum and peritoneal fluid concentrations of selected markers in healthy controls and women with endometriosis before surgery and in serum 5 to 7 days after surgery. Women with endometriosis had elevated levels of VEGF-A, sVEGFR-1, and Ang-2 in serum and all studied markers in peritoneal fluid compared with healthy controls. Surgical removal of endometriotic lesions resulted in decreased serum levels of pro-angiogenic VEGF-A and increased levels of sVEGFR-2 that negatively regulates the action of VEGF. Women with advanced endometriosis have serum and peritoneal fluid concentrations of several factors involved in the regulation of angiogenesis that differ from those in healthy women, and these changes at least partly normalize within a week after surgical removal of the endometriotic lesions.

Hypercholesterolaemia impairs monocyte function in CAD patients

Hypercholesterolaemia (HC) impairs arteriogenesis, i.e. collateral artery growth. Monocytes are crucial mediators of arteriogenesis. We investigated the impact of the cardiovascular risk factor HC on ligand-induced monocyte chemotaxis. The migratory response of monocytes towards the arteriogenic ligands vascular endothelial growth factor-A (VEGF-A) and monocyte chemoattractant protein-1 (MCP-1) in hypercholesterolaemic coronary artery disease (CAD) patients (n = 14), hypercholesterolaemic controls (n = 8) and age-matched healthy controls (n = 19) was analysed. Furthermore, the serum VEGF-A level was determined in all individuals. VEGF-A-induced monocyte chemotaxis was severely impaired in hypercholesterolaemic CAD patients when compared with age-matched healthy controls (P < 0.001). The same was true for the migratory response towards MCP-1 (P < 0.001). VEGF-A- and MCP-1-induced monocyte chemotaxis of hypercholesterolaemic controls was also decreased in comparison with the healthy control group, but not as severe as observed in the hypercholesterolaemic CAD patients. VEGF-A serum levels did not differ between the three study groups. Hypercholesterolaemia severely impairs monocyte function in hypercholesterolaemic CAD patients. Monocyte dysfunction is probably connected to impaired collateral artery growth. The duration of the cardiovascular risk factor HC seems to influence the extent of monocyte dysfunction, as there exists a continuum of diminished monocyte chemotaxis in the three study groups. Further trials are warranted in order to determine whether statins can reverse the negative influence of HC on cell function.

Correlation between High Vascular Endothelial Growth Factor-A Serum Levels and Treatment Outcome in Patients with Standard-Risk Acute Lymphoblastic Leukemia: A Report from Children's Oncology Group Study CCG-1962

Many molecular pathways, including cell cycle control, angiogenesis, and drug resistance, mediate tumor growth and survival. Vascular endothelial growth factor-A (VEGF-A) serum levels <40 and >100 pg/mL have been associated with good and poor prognoses, respectively. The hypothesis was that serum VEGF-A levels in standard-risk acute lymphoblastic leukemia pediatric patients at induction are predictive of event-free survival (EFS). One hundred seventeen patients were entered in CCG-1962 study and randomized into the native and polyethylene glycolated asparaginase arms. VEGF-A levels were quantified by an ELISA assay. All patients had a decrease in VEGF-A levels by day 14 of induction, but they later dichotomized; EFS group levels remained low and event group levels increased. A correlation exists between high VEGF-A levels at entry to induction and time to event. Moreover, 6-year EFS patients have lower end of induction VEGF-A levels (28 +/- 6 pg/mL) than event patients (>100 pg/mL; P < 0.01). Kaplan-Meier curves using various VEGF-A values were produced; with < or =30 at entry into induction (day 0) and < or =60 pg/mL at the end of induction (day 28), patients with low VEGF-A levels had superior EFS (P < 1e-4). Furthermore, patients who had an increase in VEGF-A during induction (DeltaVEGF-positive, days 0-28) were more likely to have an event (P < 1e-4). Bifurcation by asparaginase treatment arm did not alter these results. These observations strongly support that high VEGF-A levels in induction are an asparaginase treatment-independent predictive marker for EFS. Hence, an anti-VEGF-A therapy should be tested in acute lymphoblastic leukemia.

Elevation of Vascular Endothelial Growth Factor-A Serum Levels Following Acute Myocardial Infarction. Evidence for its Origin and Functional Significance

A. Kranz, C. Rau, M. Kochs and J. Waltenberger. Elevation of Vascular Endothelial Growth Factor-A Serum Levels Following Acute Myocardial Infarction. Evidence for its Origin and Functional Significance. Journal of Molecular and Cellular Cardiology (2000) 32, 65–72. Following the onset of acute myocardial infarction (AMI), a number of serum parameters show well-defined changes reflecting myocardial injury. During the consecutive repair phase, compensatory processes are initiated including the formation of a collateral circulation on the basis of angiogenesis and arteriogenesis. An important angiogenic factor is vascular endothelial growth factor-A (VEGF-A), shown to be upregulated in the ischemic myocardium. It is unclear, however, whether acute myocardial ischemia leads to a detectable elevation of VEGF-A serum concentrations. With the use of an immunoradiometric assay, we measured the levels of VEGF-A in the serum of patients after AMI at defined time intervals, of patients with unstable angina pectoris (UAP) and of healthy individuals. In addition, in a small group of patients with subacute myocardial infarction VEGF-A concentrations were measured in coronary sinus blood. The data are given as median followed by the 25th and 75th percentiles. In the group with AMI serum VEGF-A measured 105 [78; 176] pg/ml on day 1 and 114 pg/ml [72; 163] pg/ml on day 3 after onset of AMI. Serum levels of VEGF-A significantly increased on day 7 after AMI to 189 [119; 373] pg/ml (P=0.0103) and on day 10 to 255 [162; 371] pg/ml (P=0.0007). The VEGF-A serum level in healthy controls and in patients with UAP measured 98 [75; 137] pg/ml and 116 [57; 140] pg/ml, respectively. Serum at day 10 after AMI contained VEGF-A at a biologically relevant concentration capable of stimulating proliferation of endothelial cells. Surprisingly, VEGF-A serum levels were similar in samples taken from the coronary sinus with 61 [43; 83] pg/ml. Therefore the main source for VEGF-A in the blood stream is not the infarcted myocardium. However, the number of platelets, a rich source of VEGF-A, is significantly increased after myocardial infarction, i.e. 284 [252; 363]×109/litre v 220 [177; 250]×109/litre. In conclusion, the time course of VEGF-A elevation following AMI strongly suggests that VEGF-A plays a role as an endogenous activator of coronary collateral formation in the human heart. The most likely source of the elevated VEGF-A are platelets, rather than the infarcted myocardium.