Evidence for association of coronary sinus levels of hepatocyte growth factor and collateralization in human coronary disease

Relationship between thrombospondin-1, endostatin, angiopoietin-2, and coronary collateral development in patients with chronic total occlusion

This study is aimed to investigate whether serum angiostatic factors (thrombospondin-1 [TSP-1] and endostatin) or angiogenic factors (angiopoietin-2 [Ang-2]) are related to coronary collateral vessel development in patients with chronic total occlusion (CTO).A total of 149 patients were enrolled in the study, and 39 patients with coronary artery disease but without significant stenosis were included in control group. In 110 patients with CTO lesion, 79 with Rentrop grades 2 to 3 collaterals were grouped as good collateral, while 31 with Rentrop grades 0 to 1 collaterals were grouped as poor collateral. Serum TSP-1, endostatin, and Ang-2 levels were studied.Serum endostatin level was significantly higher in poor collateral group compared with control group and good collateral group, respectively (96.2 ± 30.4 vs 77.8 ± 16.5 ng/mL, P = 0.007; 96.2 ± 30.4 vs 81.2 ± 30.4 ng/mL, P = 0.018). In multivariate analysis, decreased serum endostatin level was independently related to good coronary collateral development. Serum TSP-1 level was lower in patients with CTO compared with control group. However, no difference in TSP-1 level was detected between poor and good collateral group. The serum Ang-2 level did not show a significant difference among 3 groups.Circulatory endostatin may be a useful biomarker for coronary collateral development and potential target for therapeutic angiogenesis in patients with CTO.

Circulating neuregulin-1β levels vary according to the angiographic severity of coronary artery disease and ischemia

BACKGROUND

Coronary artery disease (CAD) is the leading killer in the United States. Patients with severe CAD and ischemia have worse prognosis. Therefore expansion of biomarker research, to identify at-risk individuals and explain the complex biology between cardiovascular growth factors and atherosclerosis is needed. Neuregulin-1β (NRG-1β) is a myocardial stress activated growth and survival factor released from endocardial and endothelial cells. NRG-1β is essential for cardiovascular development and a regulator of angiogenesis. We postulated that plasma and serum levels of NRG-1β would vary in relation to CAD severity and the presence of stress-induced ischemia.

METHODS

We measured serum and plasma levels of NRG-1β and vascular endothelial growth factor (VEGF) in 60 patients undergoing cardiac catheterization. CAD severity was calculated from angiographic results using a modified Duke jeopardy score.

RESULTS

Serum NRG-1β (sNRG-1β), plasma NRG-1β (pNRG-1β), serum VEGF, and plasma VEGF were detectable in the majority of patients. The pNRG-1β levels were approximately two-fold higher than sNRG-1β. Both sNRG-1β and pNRG-1β correlated inversely with CAD severity. pNRG-1β levels were statistically higher in patients with stress-induced ischemia denoted by a positive myocardial perfusion imaging study that correlated with angiographic findings (P=0.02).

CONCLUSION

Both sNRG-1β and pNRG-1β correlated inversely with angiographic severity of CAD. pNRG-1β levels were two-fold higher than serum and were higher in patients with stress-induced ischemia. Therefore we conclude that plasma is the optimal source for the further exploration of the biological significance of NRG-1β as a biomarker of CAD severity and ischemia.

Human studies of angiogenic gene therapy

Despite significant advances in medical, interventional, and surgical therapy for coronary and peripheral arterial disease, the burden of these illnesses remains high. To address this unmet need, the science of therapeutic angiogenesis has been evolving for almost two decades. Early preclinical studies and phase I clinical trials achieved promising results with growth factors administered as recombinant proteins or as single-agent gene therapies, and data accumulated through 10 years of clinical trials indicate that gene therapy has an acceptable safety profile. However, more rigorous phase II and phase III clinical trials have failed to unequivocally demonstrate that angiogenic agents are beneficial under the conditions and in the patients studied to date. Investigators have worked to understand the biology of the vascular system and to incorporate their findings into new treatments for patients with ischemic disease. Recent gene- and cell-therapy trials have demonstrated the bioactivity of several new agents and treatment strategies. Collectively, these observations have renewed interest in the mechanisms of angiogenesis and deepened our understanding of the complexity of vascular regeneration. Gene therapy that incorporates multiple growth factors, approaches that combine cell and gene therapy, and the administration of "master switch" agents that activate numerous downstream pathways are among the credible and plausible steps forward. In this review, we examine the clinical development of angiogenic gene therapy, summarize several of the lessons learned during the conduct of these trials, and suggest how this prior experience may guide the conduct of future preclinical investigations and clinical trials.

CXCR4 expression determines functional activity of bone marrow-derived mononuclear cells for therapeutic neovascularization in acute ischemia

OBJECTIVE

Bone marrow-derived mononuclear cells (BMCs) improve the functional recovery after ischemia. However, BMCs comprise a heterogeneous mixture of cells, and it is not known which cell types are responsible for the induction of neovascularization after cell therapy. Because cell recruitment is critically dependent on the expression of the SDF-1-receptor CXCR4, we examined whether the expression of CXCR4 may identify a therapeutically active population of BMCs.

METHODS AND RESULTS

Human CXCR4(+) and CXCR4(-) BMCs were sorted by magnetic beads. CXCR4(+) BMCs showed a significantly higher invasion capacity under basal conditions and after SDF-1 stimulation. Hematopoietic or mesenchymal colony-forming capacity did not differ between CXCR4(+) and CXCR4(-) BMCs. Injection of CXCR4(+) BMCs in mice after induction of hindlimb ischemia significantly improved the recovery of perfusion compared to injection of CXCR4(-) BMCs. Likewise, capillary density was significantly increased in CXCR4(+) BMC-treated mice. Because part of the beneficial effects of cell therapy were attributed to the release of paracrine effectors, we analyzed BMC supernatants for secreted factors. Importantly, supernatants of CXCR4(+) BMCs were enriched in the proangiogenic cytokines HGF and PDGF-BB.

CONCLUSIONS

CXCR4(+) BMCs exhibit an increased therapeutic potential for blood flow recovery after acute ischemia. Mechanistically, their higher migratory capacity and their increased release of paracrine factors may contribute to enhanced tissue repair.

Effect of hepatocyte growth-promoting factors on myocardial ischemia during exercise in patients with severe coronary artery disease

Hepatocyte growth-promoting factor (pHGF) has the greatest potential as a therapeutic agent for vascular growth factor. The aim of this study was to investigate the effect of pHGF on myocardial ischemia and exercise capacity in patients with severe coronary artery disease (CAD). Forty-nine patients were enrolled for a two week treatment period. Treadmill graded exercise tests with gas analysis were conducted before and after therapy. Serum levels of HGF were significantly elevated after therapy. The degrees of exercise-induced ST segment depression were decreased more significantly in the pHGF group. Similar differences were also found in the maximum heart rate and the maximum heart rate when the ST segment was depressed 1 mm while undergoing the treadmill graded exercise test. Both were increased more significantly in the pHGF group. Total exercise time, systolic blood pressure in the peak of exercise, the length of time that ST segment depression of 1 mm is needed, and total work all were increased in both groups after intervention. Furthermore, total exercise time and total work were increased more significantly in the pHGF group. The levels of HGF increased significantly after pHGF treatment. pHGF could favorably improve exercise-induced myocardial ischemia and enhance exercise capacity in patients with severe CAD.

Systemic and intracardiac vascular endothelial growth factor and angiopoietin-1 and -2 levels in coronary artery disease: effects of angioplasty

BACKGROUND

Vascular growth factors are involved in the pathophysiology of human atherosclerotic vascular disease and plaque destabilization. We hypothesized that in stable patients with coronary artery disease (CAD), plasma levels of vascular endothelial growth factor (VEGF) and angiopoietins 1 and 2 (as indices of angiogenesis) would be no higher in coronary sinus blood when compared to the aortic root, coronary ostium, and peripheral femoral vein. Secondly, we hypothesized that percutaneous coronary intervention (PCI; angioplasty+/-stenting) would increase intracardiac levels of these indices, perhaps by destabilizing coronary plaques.

METHODS

Patients undergoing elective diagnostic coronary angiography (n = 70; mean age 58.8+/-11.2 years) of which 37 proceeded to PCI were recruited. Blood samples were obtained from the aortic root, coronary ostium, coronary sinus, and femoral vein. Plasma VEGF, angiopoietin-1 and angiopoietin-2 levels were measured by immunoassays.

RESULTS

There were no significant differences in VEGF, angiopoietin-1 and angiopoietin-2 levels when aortic root, coronary ostium, coronary sinus, and femoral vein samples were compared (P = not significant (NS)). In patients undergoing PCI, peripheral angiopoietin-2 levels were increased significantly post PCI (P = 0.01). There was also a difference in intracardiac gradient (that is, aortic root-coronary sinus difference) in angiopoietin-1 (P = 0.02) following PCI. No significant changes in VEGF with PCI were noted.

CONCLUSION

There were no differences in indices of angiogenesis when aortic root, coronary ostium, coronary sinus, and femoral vein levels of VEGF and angiopoietins are compared, suggesting that peripheral blood measurements of these indices are comparable to intracardiac levels. Although no immediate effects were observed in soluble VEGF levels, PCI affected intracardiac angiopoietin-1 with a systemic release of angiopoietin-2. Further investigations are necessary to determine the relative systemic and intracardiac effects of the angiopoietins in vascular remodelling post PCI.

Humoral and cellular factors responsible for coronary collateral formation

Clinical observations suggest that patients with coronary artery disease (CAD) display a marked heterogenerty in collateral formation despite similar degrees of coronary obstruction. The development of coronary collaterals helps protect the myocardium from ischemic damage, yet the factors responsible for collateral formation are poorly understood. To better understand the biochemical and cellular mechanisms of collateral artery formation, monocyte function and circulating levels of pro- and antiangiogenic factors were measured in 101 patients with angiographically assessed CAD and extensively developed (score 2, n = 33) or absent (score 0, n = 68) collateral circulations. Compared with patients with score 0, those with score 2 were slightly older and had more advanced CAD. The score 2 group was also more likely to have had a previous myocardial infarction or coronary artery bypass grafting and a family history of CAD. At the same time, there were no significant differences between groups with regard to circulating levels of vascular endothelial growth factor-A(165), platelet-derived growth factor-betabeta, fibroblast growth factor-2, fibroblast growth factor-4, hepatocyte growth factor, tumor necrosis factor-alpha, interleukin-1beta, endostatin, matrix metalloproteinase-9, promatrix metalloproteinase-1, and CD40 ligand. Monocytes isolated from patients with score 2 and 0 collateral circulations demonstrated no differences in migration assays. However, adhesion to fibrinogen and collagen was significantly higher for monocytes from patients with score 0 (p = 0.05 and 0.04, respectively). In conclusion, these data suggest that the degree of coronary collateral formation is not determined by differences in systemically measurable levels of pro- or antiangiogenic factors assessed in this study. Rather, cellular properties, such as cell adhesion, or genetic differences between patients may be the driving force for collateral development.

Mobilization of CD34/CXCR4+, CD34/CD117+, c-met+ stem cells, and mononuclear cells expressing early cardiac, muscle, and endothelial markers into peripheral blood in patients with acute myocardial infarction

BACKGROUND

Adult stem cells can contribute to myocardial regeneration after ischemic injury. Bone marrow and skeletal muscles contain a population of CXCR4+ cells expressing genes specific for muscle progenitor cells that can be mobilized into the peripheral blood. The aims of the study were (1) to confirm the presence of early tissue-committed cells expressing cardiac, muscle, and endothelial markers in populations of mononuclear cells in peripheral blood and (2) to assess the dynamics and magnitude of the mobilization of CD34+, CD117+, CXCR4+, c-met+, CD34/CD117+, and CD34/CXCR4+ stem cells into peripheral blood in relation to inflammatory and hematopoietic cytokines in patients with ST-segment-elevation acute myocardial infarction (STEMI).

METHODS AND RESULTS

Fifty-six patients with STEMI (<12 hours), 39 with stable angina, and 20 healthy control subjects were enrolled. Real-time reverse transcription-polymerase chain reaction (RT-PCR) was used for detection of tissue-specific markers. The number of the cells was assessed by use of a flow cytometer on admission, after 24 hours, and after 7 days. RT-PCR revealed increased expression of mRNA (up to 3.5-fold increase) for specific cardiac (GATA4, MEF2C, Nkx2.5/Csx), muscle (Myf5, Myogenin, MyoD), and endothelial (VE-cadherin, von Willebrand factor) markers in peripheral blood mononuclear cells. The number of CD34/CXCR4+ and CD34/CD117+ and c-met+ stem cells in peripheral blood was significantly higher in STEMI patients than in stable angina and healthy subjects, peaking on admission, without further significant increase after 24 hours and 7 days.

CONCLUSIONS

The study demonstrates in the setting of STEMI a marked mobilization of mononuclear cells expressing specific cardiac, muscle, and endothelial markers as well as CD34/CXCR4+ and CD34/CD117+ and c-met+ stem cells and shows that stromal cell-derived factor-1 is an important factor influencing the mobilization.