Coronary Endothelial Injury Research Articles

Abstract 12560: Effect of Somah Solution on Hypoxia/Reoxygenation Induced Coronary Artery Endothelial Injury: A Comparison to Current Ex-Vivo Heart Perfusates

Introduction: Ex-Vivo Heart Perfusion (EVHP) has been proposed to expand cardiac donation by enabling resuscitation and preservation of hearts donated after circulatory death. Hypoxia/reoxygenation endothelial injury affects organ viability and patient’s outcomes. STEEN Solution is accepted as the primary component for perfusion of other solid organs. However, there is lack of evidence to determine the optimal perfusate composition to maintain cardiac viability during longer periods of perfusion. Somah solution has been proposed as a novel cardioprotective solution optimized to meet cardiac metabolism and confer enhanced protective effects against reperfusion injury. Our aim was to compare the effects of STEEN and Somah on endothelial reoxygenation injury in vitro. Methods: Human coronary artery endothelial cells were exposed to 16 hours of hypoxia in culture medium followed by 16 hours of reoxygenation treated with Celsior, STEEN or Somah to simulate the EVHP setting. Endothelial activation markers’ gene expression was assessed through qRT-PCR; supernatant was collected to quantify endothelin-1 (ET-1) with ELISA; and quantitative neutrophil adhesion assay was performed to evaluate endothelial function. Results: Treatment with Somah demonstrated decreased expression of cell surface adhesion molecules E-Selectin (Me 0.133±0.12, So -0.073±0.34, ST 1.624±0.46, Ce 0.999±0.45 fold-change from hypoxia; p=0.002) and VCAM-1 (Me -0.004±0.20, So -0.363±0.43, ST 0.428±0.39, Ce 0.597±0.13 fold-change from hypoxia; p=0.023), and vasoactive molecule MCP-1 (Me 0.225±0.72, So -0.510±0.70, ST 1.500±0.49, Ce 0.829±0.28 fold-change from hypoxia; p=0.015). Celsior and Somah reduced cell secretion of ET-1 (Me 395 pg/ml, So 20 pg/ml, ST 448 pg/ml, Ce 16 pg/ml; n=4, p<0.05). Reoxygenation injury increased neutrophil adhesion to endothelial cells; there was a non-statistically significant trend towards protection against this injury with Somah. Conclusions: Somah exerts protective effect against reoxygenation injury when compared to STEEN in vitro. It may have utility in enhancing cardiac organ preservation during EVHP. Future studies in a pre-clinical setting should be conducted to address this question.

MicroRNA-130a alleviates human coronary artery endothelial cell injury and inflammatory responses by targeting PTEN via activating PI3K/Akt/eNOS signaling pathway.

Our study aims to investigate the roles of microRNA-130a (miR-130a) in human coronary artery endothelial cells (HCAECs) injury and inflammatory responses by targeting PTEN through the PI3K/Akt/eNOS signaling pathway. HCAECs were treated with 1.0 mmol/L homocysteine (HCY) and assigned into eight groups: the blank group, the negative control (NC) group, the miR-130a mimics group, the miR-130a inhibitors group, the si-PTEN group, the Wortmannin group, the miR-130a inhibitors + si-PTEN group and the miR-130a mimics + Wortmannin group. Luciferase reporter gene assay was used to validate the relationship between miR-130a and PTEN. The expressions of miR-130a, PTEN and PI3K/Akt/eNOS signaling pathway-related proteins were detected by qRT-PCR assay and Western blotting. MTT assay and Hoechst 33258 staining were adopted to testify cell growth and apoptosis. The NO kit assay was used to detect the NO release. ELISA was conducted to measure serum cytokine levels. Luciferase reporter gene assay confirmed the target relationship between miR-130a and PTEN. Compared with the blank and NC groups, the miR-130a mimics and si-PTEN groups showed significant increases in the expressions of PI3K/Akt/eNOS signaling pathway-related proteins, cell viability and the NO release, while serum cytokine levels and cell apoptosis were decreased; by contrast, an opposite trend was observed in miR-130a inhibitors and Wortmannin groups. However, no significant difference was found in the miR-130a inhibitors + si-PTEN and miR-130a mimics + Wortmannin groups when compared with the blank group. These results indicate that miR-130a could alleviate HCAECs injury and inflammatory responses by down-regulating PTEN and activating PI3K/Akt/eNOS signaling pathway.

Effects of 20-minute warm ischemia on coronary endothelial function of pig donor hearts after cardiac death

BACKGROUND: Myocardial and coronary endothelial injury occurs in donor hearts due to warm ischemia during cardiac transplantation. Coronary endothelial structure and function play a critical role in long-term outcomes for patients after cardiac transplantation. OBJECTIVE: To study the effect of hypoxia-induced warm ischemia (20 minutes) on coronary endothelial function of porcine donor hearts after cardiac death (DCD). METHODS: Sixteen healthy Swedish domestic pigs were randomized into control (n=6), DCD (n=5), and DCD plus cold storage (n=5) groups, respectively. A DCD model in pigs was established using the method of hypoxia-induced 20-minute warm ischemia in the DCD and DCD plus cold storage groups. Isolation of the heart left anterior descending coronary artery or combined with heart preservation pretreatment for 4 hours was performed in the DCD and DCD plus cold storage groups. The maximum coronary endothelium-dependent relaxation was determined in the three groups. RESULTS AND CONCLUSION: There were no significant differences in the maximum coronary endothelium-dependent relaxation and the minus logarithmic of substance concentration induced 50%maximal relaxation among three groups (P > 0.05). These results indicate that 20-minute warm ischemia cannot lead to obvious coronary endothelial dysfunction. In addition, DCD combined with 4-hour cold storage does not affect coronary endothelial function. (Less)

Angiotensin Type 1 Receptor Antibodies and Cardiac Allograft Vasculopathy Late After Heart Transplantation: A New Pathway for Coronary Endothelial Injury?

Angiotensin Type 1 Receptor Antibodies and Cardiac Allograft Vasculopathy Late After Heart Transplantation: A New Pathway for Coronary Endothelial Injury?

Coronary flow velocity reserve is impaired in hypertensive patients with hyperhomocysteinemia

Hyperhomocysteinemia (HHcy) is an independent risk factor for coronary artery disease. Chronic HHcy induces coronary endothelial injury, and homocysteine (Hcy) inhibits insulin sensitivity by inducing endoplasmic reticulum stress in adipose tissue. However, the combined effects of chronic HHcy and hypertension on coronary artery endothelial function have still remained unclear. Fifty-one patients with essential hypertension (HT) were recruited, and were divided into nHT group (without HHcy) and H-type HT group (with HHcy). Forty healthy subjects were enrolled as controls. We assessed coronary artery endothelial function by coronary flow velocity reserve (CFVR). Hcy levels were significantly higher (15.60±6.58 vs 13.08±4.13 μmol l(-1), P<0.05), whereas CFVR values were significantly lower in the HT patients than in the control group (2.88±0.70 vs 3.23±0.54, P<0.05). Hcy levels were negatively correlated with CFVR value (r=-0.578, P<0.01, 95% confidence interval -0.085 to -0.046). The homeostasis model assessment-insulin resistance values were significantly higher (3.92±2.16 vs 2.72±1.50, P<0.05) , whereas CFVR values were significantly lower in H-type HT group than in nHT group (2.31±0.31 vs 3.25±0.62, P<0.01). Coronary artery endothelial function may be impaired in essential hypertensive patients with HHcy, and insulin resistance induced by HHcy may contribute to this damage.

Myocardial protective effects of micro-flow perfusion with blood Plegisol solution

Objective To study the myocardial protective effect of micro-flow perfusion with blood Plegisol solution on warm ischemic pig heart and the mechanism.Methods Twelve isolated pig hearts were subjected to orthotopic heart transplantation and randomly divided into experimental group (n =6,warm ischemia for 10 min,4℃ blood the micro-flow continuous infusion for 8 h,and warm-blooded continuous perfusion during transplantation) and control group (n =6,wark ischemia for 10 min,and immersion with 4℃ Plegisol liquid alone for 8 h).The pathological changes of myocardial tissue in all pig hearts after reperfusion were observed.The superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in myocardial tissue were measured by xanthine oxidase and thiobarbituric acid method.Immunohistochemistry was used to detect B lymphocytes/leukemia-2 (bcl-2) and Caspase-3 protein expression.Results In control group,coronary endothelial and myocardial tissue injury was more serious than in experimental group.As compared with control group,myocardial tissue SOD activity [(7.88 ± 0.41) U/(mg· protein)] was significantly increased,and MDA content [(9.97 ± 1.05) nmol/(mg· protein)] was significantly reduced in experimental group (P ＜ 0.05).The expression levels of bcl-2 mRNA and protein in experimental group (0.651 ±0.052 and 0.506 ±0.048) were significantly increased as compared with control group (0.337 ±0.026 and 0.271 ±0.022),and those of Caspase-3 mRNA and protein in experimental group (0.343 ± 0.027 and 0.215 ± 0.019) were significantly decreased as compared with control group [(0.782 ±0.059 and 0.629 ±0.054),P ＜0.01].Conclusion The mechanism by which micro-flow perfusion with blood Plegisol solution protects warm ischemic pig heart may be related to the alleviation of the isolated pig heart coronary endothelial and myocardial edema,reduction of the reperfusion oxidative damage and the inhibition of cardiac apoptosis. Key words: Micro-flow infusion; Warm ischemic; Myocardial protective

317 Impact of Routinely Performed Coronary Angiography in Older Heart Donors on Heart Transplantation Results

tients at increased risk for poor outcomes, particularly the development of cardiac allograft vasculopathy (CAV). Smoking is known to cause coronary endothelial cell injury. However, the role of donor smoking history is unclear. The purpose of the current study was to assess the effect of donor smoking on outcomes of heart transplant recipients. Methods and Materials: We assessed 394 patients transplanted from 1994 to 2010 for donor history of smoking. There were 216 patients whose donor had a smoking history and 178 patients whose donor did not smoke. Outcomes were compared between groups: 5-year survival, 5-year freedom from CAV (stenosis 30%), 5-year freedom from non-fatal major adverse cardiac events (NF-MACE: MI, heart failure, stenting, defibrillator, stroke, and new peripheral vascular disease), and 1-year freedom from any-treated rejection. Results: Recipient age, gender, donor age, reason for transplant, CMV mismatch were similar between groups. Patients in the donor smoking group had a significantly lower 5-year freedom from CAV compared to patients in the donor non-smoking group (78% vs. 88%, p 0.014; figure). However, other outcomes were similar, including 5-year survival (77% vs. 76%, p 0.82), freedom from NF-MACE (87% vs. 85%, p 0.62), and 1st-year freedom from any-treated rejection (92% vs. 90%, p 0.53).

Elevated Soluble fms-Like Tyrosine Kinase-1 Levels in Acute Coronary Occlusion

Early recognition of an acute coronary occlusion (ACO) improves clinical outcomes. Soluble fms-like tyrosine kinase-1 (sFLT1) is an endothelium-derived protein induced by hypoxia. We tested whether sFLT1 levels are elevated in ACO. Serum sFLT1 levels were measured by enzyme-linked immunosorbent assay in patients with ST-segment elevations and angiographically confirmed ACO, unstable angina/non ST-segment elevation myocardial infarction, and 2 control groups. To further explore sFLT1 release, a mouse model of ACO and in vitro human coronary artery endothelial cell injury were used. sFLT1 levels were increased in ACO compared with unstable angina/non-ST-elevation myocardial infarction, catheterized controls, or healthy volunteers (200.7±15.5 versus 70.7±44.0 versus 10.2±4.0 versus 11.7±1.7 pg/mL respectively, P<0.001 versus ACO). At presentation, all ACO patients had elevated sFLT1 levels (>15 pg/mL, 99th percentile in controls), whereas 57% had levels of the MB isoform of creatine kinase levels >10 ng/mL (P<0.01) and 85% had ultrasensitive troponin I levels >0.05 ng/mL (P<0.05). Within 60 minutes after symptom onset, sFLT1 was more sensitive than the MB isoform of creatine kinase or ultrasensitive troponin I for ACO (100% versus 20% versus 20% respectively; P≤0.01 for each). Within 60 minutes of ACO in mice, sFLT1 levels were elevated. Hypoxia and thrombin increased sFLT1 levels within 15 minutes in human coronary artery endothelial cells. sFLT1 levels may be an early indicator of endothelial hypoxia in ACO.

Sivelestat reduces myocardial ischemia and reperfusion injury in rat hearts even when administered after onset of myocardial ischemia

Sivelestat, a neutrophil elastase inhibitor, has been shown to attenuate pulmonary injury during ischemia and reperfusion by improving microcirculation and may be effective as a cardioprotective agent. Isolated rat hearts were Langendorff-perfused (constant pressure, 75 mmHg) with oxygenated Krebs-Henseleit bicarbonate buffer (KHB). The optimal sivelestat concentration at 19 micromol/l was revealed because left ventricular developed pressure (LVDP) recovery in 19 micromol/l sivelestat was highest among 0.19, 1.9, 19, 190, and 1900 micromol/l sivelestat (26+/-10, 33+/-7, 56+/-5*, 35+/-2, and 15+/-5%, respectively; *P<0.01). In order to examine the optimal administration timing, sivelestat was administered at pre- and post-ischemic phases. LVDP recovery and troponin-T were observed in pre-, post-ischemic sivelestat groups and control. After 60 min-reperfusion, LVDP recoveries were 42+/-10*, 45+/-19*, and 14+/-5%, respectively (*P<0.01 compared to control), and troponin-T values were 4+/-1, 2+/-1**, and 8+/-2, respectively (**P<0.05 compared to control). Acetylcholine-induced increase in coronary flow was also investigated to examine the sivelestat's cardioprotective mechanism. Ischemia-reperfusion (I/R) impaired the acetylcholine-induced increase in coronary flow (maximal changes: sham, 125+/-11%; I/R, 98+/-3; P<0.01) and this impairment was attenuated by sivelestat-perfusion at reperfusion (maximal change: 112+/-7%; P<0.05 vs. I/R). Sivelestat attenuates coronary endothelial ischemia-reperfusion injury and improves myocardial protection even when administered at the reperfusion period. This suggests a role for sivelestat in the preservation of coronary endothelial function enhancing myocardial protection.

Toll-Like Receptors 2-Deficient Mice Are Protected Against Postischemic Coronary Endothelial Dysfunction

Toll-like receptors (TLR) 2 are expressed in cardiac and inflammatory cells, and regulate leukocyte function. Because leukocyte adhesion is a critical event in endothelial injury induced by ischemia/reperfusion (I/R), we assessed whether TLR2 were involved in I/R-induced coronary endothelial injury. Ischemia-reperfusion markedly decreased NO-mediated coronary relaxations to acetylcholine assessed ex vivo. In contrast, in TLR2 deficient mice, I/R paradoxically improved the NO-mediated responses to acetylcholine. To precise the cellular compartment expressing TLR2 which is involved in endothelial injury, we developed bone-marrow chimeric mice by transplanting TLR2-/- bone marrow to WT mice or WT bone marrow to TLR2-/- mice and submitted them to I/R 5 weeks after transplant. Both chimeric mice displayed similar protection as TLR2-/- mice against I/R-induced endothelial dysfunction, suggesting a role of TLR2 expressed on both non-bone marrow cells (in our case presumably endothelial cells and/or cardiomyocytes) and cells of bone marrow origin (presumably neutrophils). TLR2 deficiency was also associated with a smaller infarct size, and reduced reperfusion-induced production of reactive oxygen species and leukocyte infiltration. TLR2 contribute to coronary endothelial dysfunction after I/R, possibly through stimulation of neutrophil- (and free radical-) mediated endothelial injury.

P38 Mitogen-Activated Protein Kinase Mediates Palmitate-Induced Apoptosis But Not Inhibitor of Nuclear Factor-κB Degradation in Human Coronary Artery Endothelial Cells

Plasma free fatty acids are elevated in patients with type 2 diabetes and contribute to the pathogenesis of insulin resistance and endothelial dysfunction. The p38 MAPK mediates stress, inflammation, and apoptosis. Whether free fatty acids induce apoptosis and/or activate nuclear factor-kappaB inflammatory pathway in human coronary artery endothelial cells (hCAECs) and, if so, whether this involves the p38 MAPK pathway is unknown. hCAECs (passages 4-6) were grown to 70% confluence and then incubated with palmitate at concentrations of 0-300 microm for 6-48 h. Palmitate at 100, 200, or 300 microm markedly increased apoptosis after 12 h of incubation. This apoptotic effect was time (P=0.008) and dose (P=0.006) dependent. Palmitate (100 microm for 24 h) induced a greater than 2-fold increase in apoptosis, which was accompanied with a 4-fold increase in p38 MAPK activity (P<0.001). Palmitate did not affect the phosphorylation of Akt1 or ERK1/2. SB203580 (a specific inhibitor of p38 MAPK) alone did not affect cellular apoptosis; however, it abolished palmitate-induced apoptosis and p38 MAPK activation. Palmitate significantly reduced the level of inhibitor of nuclear factor-kappaB (IkappaB). However, treatment of cells with SB203580 did not restore IkappaB to baseline. We conclude that palmitate induces hCAEC apoptosis via a p38 MAPK-dependent mechanism and may participate in coronary endothelial injury in diabetes. However, palmitate-mediated IkappaB degradation in hCAECs is independent of p38 MAPK activity.

Preconditioning protects endothelium by preventing ET-1-induced activation of NADPH oxidase and xanthine oxidase in post-ischemic heart

The hypothesis was tested that endothelin-1 (ET-1)-induced superoxide (O 2 −) generation mediates post-ischemic coronary endothelial injury, that ischemic preconditioning (IPC) affords endothelial protection by preventing post-ischemic ET-1, and thus O 2 −, generation, and that opening of the mitochondrial ATP-dependent potassium channel (mK ATP) triggers the mechanism of IPC. Furthermore, the study was aimed at identifying the source of O 2 − mediating the endothelial injury. Langendorff-perfused guinea-pig hearts were subjected either to 30 min ischemia/35 min reperfusion (IR) or were preconditioned prior to IR with three cycles of either 5 min ischemia/5 min reperfusion or 5 min infusion/5 min washout of mK ATP opener diazoxide (0.5 mM). Coronary flow responses to acetylcholine (ACh) served as a measure of endothelium-dependent vascular function. Myocardial outflow of ET-1 and O 2 − and functional recoveries were followed during reperfusion. NADPH oxidase and xanthine oxidase (XO) activities were measured in cardiac homogenates. IR augmented ET-1 and O 2 − outflow and impaired ACh response. All these effects were attenuated or prevented by IPC and diazoxide, and 5-hydroxydecanoate (a selective mK ATP blocker) abolished the effects of IPC and diazoxide. Superoxide dismutase and tezosentan (a mixed ET-1-receptor antagonist) mimicked the effects of IPC, although they had no effect on the ET-1 generation. IR augmented also the activity of NADPH oxidase and XO. Apocynin treatment, that resulted in NADPH oxidase inhibition, prevented XO activation and O 2 − generation in IR hearts. The inhibition of XO, either by allopurinol or feeding the animals with tungsten-enriched chow, prevented post-ischemic O 2 − generation, although these interventions had no effect on the NADPH activity. In addition, the post-ischemic activation of NADPH oxidase and XO, and O 2 − generation were prevented by IPC, tezosentan, thenoyltrifluoroacetone (mitochondrial complex II inhibitor), and tempol (cell-membrane permeable O 2 − scavenger). In guinea-pig heart: (i) ET-1-induced O 2 − generation mediates post-ischemic endothelial dysfunction; (ii) IPC and diazoxide afford endothelial protection by attenuating the ET-1, and thus O 2 − generation, and the mK ATP opening triggers the protection; (iii) the NADPH oxidase maintains the activity of XO, and the XO-derived O 2 − mediates the endothelial injury, and (iv) ET-1 and O 2 − (probably of mitochondrial origin) are upstream activators of the NADPH oxidase–XO cascade, and IPC prevents the cascade activation and the endothelial dysfunction by preventing the ET-1 generation.

A Transfusion‐Related Acute Myocardial Injury

It is not uncommon for patients to have adverse reactions during or after blood transfusions, as they occur in 1%-6% of all blood transfusions. Although many of the reactions are clinically insignificant, a small subset of adverse reactions can lead to serious illness and even death. The authors describe a healthy young man who exhibited an acute pulmonary injury reaction to a blood product transfusion. However, he also suffered significant myocardial insult, as documented by decreased left ventricular ejection fraction and a significant rise in cardiac biomarkers. Based on current understanding of the pathophysiologic mechanisms in transfusion-related acute lung injury, the authors hypothesized that coronary endothelial injury may have caused microvascular ischemia or have induced acute myocarditis. Empiric treatment with steroids and a beta blocker resulted in improved left ventricular function in our patient.

Endothelial progenitor cell mobilization after percutaneous coronary intervention

Background In animal models, circulating endothelial progenitor cells (EPC) have been shown to participate in repair of damaged or degenerating vascular surfaces. In humans, reduced EPC counts correlate with cardiovascular risk and disease outcome; yet it has been difficult to establish that EPC are in fact mobilized in response to vascular injury as a physiologic response. We therefore studied early (<12 h) mobilization of EPCs into the peripheral circulation after a defined vascular manipulation, percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) and non-ACS patients. Methods and results CD34/CD31 positive EPC colony forming units (EPC-CFU) were quantified by a blinded observer in peripheral blood samples from eight control patients with angiographically normal coronary arteries, and in 30 patients with coronary artery lesions before and 12 h after PCI. All patients ( n = 38) had one or more CV risk factors. Ten patients presented with acute coronary syndrome (PCI ACS), and the rest ( n = 20) underwent elective PCI (PCI Elect). Despite the presence of an acute coronary syndrome, patients in the PCI ACS group did not present with increased EPC-CFU compared with either the PCI Elect or control groups ( P > 0.05). In addition, EPC-CFU (colonies/ml blood) increased significantly in the PCI Elect group after stent placement (11.8 + 1.6 before versus 16.5 + 1.9 after, P = 0.0009), while in contrast, PCI did not stimulate EPC mobilization in patients in the PCI ACS group (9.6 + 3.2 before versus 6.5 + 1.8, P = 0.20). We found a higher presenting vascular endothelial growth factor (VEGF) level in the PCI Elect group compared to PCI ACS (78.7 + 25.2 versus 15.3 + 7.9 pg/ml blood, P = 0.02). However, VEGF levels increased after PCI only in the PCI ACS group (15.3 + 7.9 to 133.3 + 27.5 pg/ml, P = 0.003) and not in the PCI Elect group (78.7 + 25.2 to 79.7 + 12.2 pg/ml, P = 0.97). Conclusion Our findings suggest that focal coronary endothelial injury as a result of PCI triggers early mobilization of EPC into the peripheral circulation in patients presenting for an elective PCI, without a corresponding rise in VEGF levels. In contrast, patients with an acute coronary syndrome fail to respond to PCI with early EPC mobilization despite a significant rise in VEGF. The results of the present study may suggest a novel mechanism for early EPC augmentation after PCI.

Endothelial progenitor cell mobilization after percutaneous coronary intervention

Abstract Background In animal models, circulating endothelial progenitor cells (EPC) have been shown to participate in repair of damaged or degenerating vascular surfaces. In humans, reduced EPC counts correlate with cardiovascular risk and disease outcome; yet it has been difficult to establish that EPC are in fact mobilized in response to vascular injury as a physiologic response. We therefore studied early ( Methods and results CD34/CD31 positive EPC colony forming units (EPC-CFU) were quantified by a blinded observer in peripheral blood samples from eight control patients with angiographically normal coronary arteries, and in 30 patients with coronary artery lesions before and 12h after PCI. All patients ( n =38) had one or more CV risk factors. Ten patients presented with acute coronary syndrome (PCI ACS ), and the rest ( n =20) underwent elective PCI (PCI Elect ). Despite the presence of an acute coronary syndrome, patients in the PCI ACS group did not present with increased EPC-CFU compared with either the PCI Elect or control groups ( P >0.05). In addition, EPC-CFU (colonies/ml blood) increased significantly in the PCI Elect group after stent placement (11.8+1.6 before versus 16.5+1.9 after, P =0.0009), while in contrast, PCI did not stimulate EPC mobilization in patients in the PCI ACS group (9.6+3.2 before versus 6.5+1.8, P =0.20). We found a higher presenting vascular endothelial growth factor (VEGF) level in the PCI Elect group compared to PCI ACS (78.7+25.2 versus 15.3+7.9pg/ml blood, P =0.02). However, VEGF levels increased after PCI only in the PCI ACS group (15.3+7.9 to 133.3+27.5pg/ml, P =0.003) and not in the PCI Elect group (78.7+25.2 to 79.7+12.2pg/ml, P =0.97). Conclusion Our findings suggest that focal coronary endothelial injury as a result of PCI triggers early mobilization of EPC into the peripheral circulation in patients presenting for an elective PCI, without a corresponding rise in VEGF levels. In contrast, patients with an acute coronary syndrome fail to respond to PCI with early EPC mobilization despite a significant rise in VEGF. The results of the present study may suggest a novel mechanism for early EPC augmentation after PCI.

Targeted vascular delivery of antisense molecules using intravenous microbubbles

Perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles bind the antisense to the c-myc protooncogene (anti-c-myc) which prevents neointimal hyperplasia following vascular endothelial injury. The microbubbles also adhere to sites of damaged vascular endothelium and thus may be a method of systemically targeting delivery of anti-c-myc. Laser scanning microscopy was performed on the aorta of 10 mice (five which were complement depleted) that received intravenous FITC-PESDA following aortic endothelial injury. C-myc expression was quantified following selective intracoronary injury in nine pigs that received intravenous (IV) anti-c-myc bound to PESDA. Finally, neointimal formation was measured following intracoronary stent deployment in 30 pigs that received either IV anti-c-myc alone or the same dose bound to PESDA. Fluorescent microscopy confirmed selective PESDA microbubble adherence to aortic endothelium in all mice with aortic injury. This binding was nearly abolished when serum complement was depleted prior to injury. C-myc expression at the site of coronary endothelial injury was significantly lower in pigs treated with systemic anti-c-myc bound to PESDA. There was a 33% reduction in % stenosis and a 28% reduction in intimal area at 45 days post-stent deployment in pigs that received IV antisense plus PESDA. The stent margins also had reduced neointimal formation. Systemic administration of anti-c-myc bound to PESDA microbubbles may be a good method for preventing coronary neointimal formation within and around implanted stents.

Myocardial protection in reperfusion with postconditioning

Reperfusion is the definitive treatment for coronary occlusive disease. However, reperfusion carries the potential to exacerbate lethal injury, termed ‘reperfusion injury’. Studies have suggested that reperfusion injury events are triggered during the early moments of reflow, and determine, in part, the severity of downstream manifestations of postischemic injury, including endothelial dysfunction, infarction and apoptosis. The application of brief iterative episodes of reflow (reoxygenation) and reocclusion (ischemia, hypoxia) at the immediate onset of reperfusion, which has been termed ‘postconditioning’ by the authors, reduces many manifestations of postischemic injury, notably infarct size, apoptosis, coronary vascular endothelial injury and reperfusion arrhythmias. Cardioprotection with postconditioning has been reported to be comparable with that observed using the gold standard maneuver ischemic preconditioning. In contrast to preconditioning, which exerts its effects primarily during the index ischemia, postconditioning appears to exert its effects during reperfusion alone. Postconditioning modifies the early phase of reperfusion in ways that are just beginning to be understood. It appears to first: reduce the oxidant burden and consequent oxidant-induced injury; secondly, attenuate the local inflammatory response to reperfusion; and thirdly, engage end effectors and signaling pathways implicated in other cardioprotective maneuvers, such as ischemic and pharmacologic preconditioning. Postconditioning seems to trigger the upregulation of survival kinases principally known to attenuate the pathogenesis of apoptosis and possibly necrosis. The postconditioning phenomenon has been reproduced by a number of independent laboratories and has been observed in both large and small animal in vivo models, as well as in ex vivo and cell culture models. In contrast to preconditioning, postconditioning may have widespread clinical application because it can be applied during reperfusion at the point of service for angioplasty, stenting, cardiac surgery and organ transplantation.

Vasculoprotective effect of insulin in the ischemic/reperfused canine heart: Role of Akt-stimulated NO production

The objectives of this study were to investigate the vasculoprotective effects of glucose-insulin-potassium (GIK) on ischemia/reperfusion-induced coronary endothelial functional injury and to elucidate the mechanism involved. Dogs were subjected to 50 min of coronary occlusion and 4 h of reperfusion. Vehicle, GIK, or GK were intravenously infused 5 min before reperfusion, and the coronary vascular dysfunction and endothelial apoptosis were determined. In a separate study, cultured endothelial cells were subjected to simulated ischemia/reperfusion, and the signaling pathway involved in insulin's anti-apoptotic effect was investigated. In vivo ischemia/reperfusion caused significant coronary vascular endothelial dysfunction as evidenced by reduced endothelium-dependent vasorelaxation, decreased nitric oxide (NO) production, and endothelial cell apoptosis as determined by caspase 3 activation and TUNEL staining. Treatment with GIK, but not GK, markedly improved the endothelium-dependent coronary vasorelaxation (P<0.01 versus vehicle), increased total NO production (P<0.01), and attenuated endothelial apoptosis. In cultured endothelial cells, treatment with insulin also markedly increased NO production and reduced simulated ischemia/reperfusion-induced apoptosis. Moreover, pre-treatment with either Akt inhibitor or NO synthase inhibitor almost abolished the anti-apoptotic effect exerted by insulin but not by SNAP, an NO donor. These results demonstrate that in vivo treatment with GIK at reperfusion attenuates ischemia/reperfusion-induced coronary endothelial dysfunction and endothelial apoptosis in an Akt-dependent and NO-mediated fashion. The coronary vasculoprotective effect elicited by insulin may contribute to the previously observed cardiac protective effect of GIK.

Myocardial ischaemia in a child infected with influenza B

Cardiac involvement is a rare complication of infection by the influenza B virus. It usually presents with ventricular dysfunction, arrhythmias, or both. We report a 13-year-old boy with clinical, electrocardiographic, and laboratory findings of myocardial ischaemia during an otherwise silent acute infection with influenza B. Coronary endothelial injury constituted a potential underlying mechanism, and microthrombosis was promoted by high levels of lipoprotein(a) in the serum.

Repeated epicardial coronary artery endothelial injuries lead to a global spontaneous coronary artery spasm.

This study was conducted to develop a spontaneous coronary spasm model. Balloon endothelial denudation was carried out in the epicardial left anterior descending coronary artery (LAD) every 2 weeks, for a total of four times, in 12 pigs. Changes in the denuded site diameter and LAD blood flow caused by acetylcholine or serotonin were assessed before each denudation and at week 8. Blood pressure, electrocardiogram (ECG) from the LAD area and LAD blood flow were monitored continuously in conscious and unrestrained pigs. Spontaneous ECG ST depression with a decrease in LAD blood flow appeared at around 2 weeks. In accordance with this, 0.5 microg/kg acetylcholine induced similar ECG and LAD blood flow changes without denuded site narrowing, suggesting microvascular spasm. Thereafter, ECG ST depression or elevation by serotonin via a denuded site spasm was found after 6 weeks and spontaneous ECG ST changes due to epicardial coronary artery spasm were observed. Epicardial coronary artery endothelial injury may induce spontaneous vasospasticity in the downstream coronary microvessels as well as in the denuded portion, suggesting functional abnormality through the entire coronary arterial tree.