Reactive oxygen species are critical mediators of coronary collateral development in a canine model

Recent evidence suggests that reactive oxygen species (ROS) promote proliferation and migration of vascular smooth muscle (VSMC) and endothelial cells (EC). We tested the hypothesis that ROS serve as crucial messengers during coronary collateral development. Dogs were subjected to brief (2 min), repetitive coronary artery occlusions (1/h, 8/day, 21 day duration) in the absence (occlusion, n = 8) or presence of N-acetylcysteine (NAC) (occlusion + NAC, n = 8). A sham group (n = 8) was instrumented identically but received no occlusions. In separate experiments, ROS generation after a single 2-min coronary artery occlusion was assessed with dihydroethidium fluorescence. Coronary collateral blood flow (expressed as a percentage of normal zone flow) was significantly increased (71 +/- 7%) in occlusion dogs after 21 days but remained unchanged (13 +/- 3%) in sham dogs. Treatment with NAC attenuated increases in collateral blood flow (28 +/- 8%). Brief coronary artery occlusion and reperfusion caused ROS production (256 +/- 33% of baseline values), which was abolished with NAC (104 +/- 12%). Myocardial interstitial fluid produced tube formation and proliferation of VSMC and EC in occlusion but not in NAC-treated or sham dogs. The results indicate that ROS are critical for the development of the coronary collateral circulation.     

Expression of VEGF and angiopoietins-1 and -2 during ischemia-induced coronary angiogenesis

The mechanisms underlying coronary capillary growth in response to ischemia are undefined. We hypothesized that the expression of vascular endothelial growth factor (VEGF) and angiopoietin (Ang)/Tie-2 were involved in capillary growth as an adaptation to ischemia. To test this hypothesis we measured capillary density, and the expressions of VEGF, Ang-1, Ang-2, and the Tie-2 receptor and its phosphorylation state during repetitive episodes of myocardial ischemia in chronically instrumented canines. Repetitive episodes of ischemia were induced by multiple (once/hour; 8/day), brief (2 min) occlusions of the left anterior descending coronary artery for 1, 7, 14, or 21 days. A sham group received the same instrumentation as the experimental groups but not the occlusion protocol. Collateral blood flow (microspheres) progressively increased from 9 +/- 3 to 83 +/- 10 ml. min-1. 100 g-1 on day 21. Capillary density increased at day 7 from 2378 +/- 53 (sham) to 2962 +/- 60/mm2, but it decreased to 2594 +/- 39/mm2 at day 21. Both VEGF and Ang-2 expression in myocardial interstitial fluid (Western analyses) peaked at day 3 of the repetitive occlusions but waned thereafter. In contrast the expression of Ang-1 remained relatively constant at all times in the occlusion groups. In shams, the expression of VEGF and Ang-2 was low and constant at all times. Tie-2 phosphorylation myocardial decreased decreased at day 7 but increased at 21 days of occlusions (P < 0.05). Our results indicate that capillary density was augmented by myocardial ischemia, but after development of collaterals and restoration of flow to the ischemic zone, capillary density returned to control levels. The change in capillary density paralleled with VEGF and Ang-2 expression but was inversely related to Tie-2 phosphorylation. We speculate the coronary angiogenesis is a coordinated event involving the expression of both VEGF and Ang-2 and that therapeutic angiogenic strategies may ultimately require treatment with more than a single factor.     

Mesenchymal stem cells are superior to angiogenic growth factor genes for improving myocardial performance in the mouse model of acute myocardial infarction

Summary Both cell therapy and angiogenic growth factor gene therapy have been applied to animal studies and clinical trials. Little is known about the direct comparison between cell therapy and angiogenic growth factor gene therapy. The goal of this study was to compare the effects of human bone marrow-derived mesenchymal stem cells (hMSCs) transplantation and injection of angiogenic growth factor genes in a model of acute myocardial infarction in mice. The hMSCs were obtained from adult human bone marrow and expanded in vitro. The purity and characteristics of hMSCs were identified by flow cytometry and immunophenotyping. Immediately after ligation of the left anterior descending coronary artery in male severe combined immunodeficient (SCID) mice, culture-expanded hMSCs or angiogenic growth factor genes were injected intramuscularly at the left anterior free wall. The engrafted hMSCs were positive for cardiac marker, desmin. Infarct size was significantly smaller in the hMSCs-treated group than in the angiopoietin-1 (Ang-1) or vascular endothelial growth factor (VEGF)-treated group at day 28 after infarction. hMSCs transplantation was better in decreasing left ventricular end-diastolic dimension and increasing fractional shortening than Ang1 or VEGF gene therapy. Capillary density was markedly increased after hMSCs transplantation than Ang1 and VEGF gene therapy. In conclusion, intramyocardial transplantation of hMSCs improves cardiac function after acute myocardial infarction through enhancement of angiogenesis and myogenesis in the ischemic myocardium. hMSCs are superior to angiogenic growth factor genes for improving myocardial performance in the mouse model of acute myocardial infarction. Transplantation of MSCs may become the future therapy for acute myocardial infarction for myocardial regeneration.     

Therapeutic myocardial angiogenesis with vascular endothelial growth factors

Emerging evidence has shown that administration of angiogenic growth factors, either as recombinant protein or by gene transfer, can augment tissue perfusion through neovascularization in animal models of myocardial and hindlimb ischemia. Many cytokines have angiogenic activity; one of those that have been best studied in animal models and clinical trials is vascular endothelial growth factor (VEGF). VEGF has been known to be a key regulator of physiologic and pathologic angiogenesis associated with tumor. Recently the effect of VEGF is not restricted to the direct angiogenic effect in vivo but includes mobilization of bone-marrow-derived endothelial progenitor cells and augmentation of postnatal vasculogenesis in situ. Clinical trials of therapeutic angiogenesis with VEGF in patients with end-stage coronary artery disease have shown increases in exercise time and reductions in anginal symptoms and have provided objective evidence of improved perfusion and left ventricular function. Larger scale placebo-controlled trials with recombinant protein (rhVEGF165) have been limited to intracoronary and intravenous administration and have shown favorable trends in exercise time and angina frequency. Small-scale, placebo-controlled, randomized clinical trials of gene transfer (phVEGF-2) via thoracotomy or percutaneous intramyocardial delivery demonstrated significant improvement of both subjective symptoms and objective measures of myocardial ischemia. Both therapeutic modalities appear to be safe and well tolerated. Further studies are required to determine the optimal dose, formulation, route of administration, and combinations of growth factors and the utility of adjunctive endothelial progenitor cell or other stem cell supplementation, to provide safe and effective therapeutic myocardial neovascularization.     

Acupuncture Promotes Angiogenesis after Myocardial Ischemia through H3K9 Acetylation Regulation at VEGF Gene

Background

Acupuncture exerts cardioprotective effects on several types of cardiac injuries, especially myocardial ischemia (MI), but the mechanisms have not yet been well elucidated. Angiogenesis mediated by VEGF gene expression and its modification through histone acetylation has been considered a target in treating myocardial ischemia. This study aims to exam whether modulation of angiogenesis through H3K9 acetylation regulation at VEGF gene is one possible cardioprotective mechanism of acupuncture.

Results

We generated rat MI models by ligating the left anterior descending coronary artery and applied electroacupuncture (EA) treatment at the Neiguan (PC6) acupoint. Our results showed that acupuncture reversed the S-T segment change, reduced Q-wave area, decreased CK, CK-MB, LDH levels, mitigated myocardial remodeling, and promoted microvessel formation in the MI heart. RNA-seq analysis showed that VEGF-induced angiogenesis signaling was involved in the modulation of EA. Western blot results verified that the protein expressions of VEGF, Ras, phospho-p44/42 MAPK, phospho-p38 MAPK, phospho-SAPK/JNK and Akt, were all elevated significantly by EA treatment in the MI heart. Furthermore, increased H3K9 acetylation was also observed according with the VEGF. ChIP assay confirmed that EA treatment could notably stimulate the recruitment of H3K9ace at the VEGF promoter.

Conclusions

Our study demonstrates for the first time that acupuncture can effectively up-regulate VEGF expression through H3K9 acetylation modification directly at the VEGF promoter and hence activate VEGF-induced angiogenesis in rat MI models. We employed high throughput sequencing in this study and, for the first time, generated genome-wide gene expression profiles both in the rat MI model and in acupuncture treatment.     

High resolution optical imaging of infarction in intact organs

We describe a method to visualize green fluorescent protein (GFP)-labeled cells in intact organs through combined confocal and reflected laser light imaging. This method allows us a three-dimensional (3-D) view of specific cell types in situ. Imaging of tissues from transgenic mice in which the endothelial cells are labeled with GFP under the control of endothelial-specific tyrosine receptor kinase 2 (TIE2) shows the spatial distribution of the GFP-labeled endothelial cells in intact organs. We have used this method to examine the tissue necrosis in the intact heart and kidney resulting from myocardial and renal infarction. In myocardial infarction produced by surgically occluding the left anterior descending coronary artery, the border of the infarct was highly cellular and showed a disrupted endothelial network and scar tissue appearing as a dense layer of reflection. The induced renal infarction produced by ligating the renal artery in the pedicle showed a clear infarct border in the affected kidney. The 3-D reconstruction of specific cell types in the context of the surrounding tissues should be useful for studying the overall organization and the relationship between different structures in the intact organ in normal and disease states.     

Assessment of collateral artery function and growth in a pig model of stepwise coronary occlusion

Therapeutic stimulation of collateral artery growth is a promising approach for treatment of cardiovascular diseases. Unfortunately, translation into clinical practice yet remains cumbersome. Cardiovascular physiology and anatomy are major determinants of vascular growth processes. Hence, large-animal models are needed to improve clinical translatability of preclinical research. Furthermore, acute complete occlusions are mostly applied in experimental research, whereas stepwise occlusions are more often observed in human disease. We developed a model of coronary collateral artery growth in which 1) the artery is occluded in a step wise approach, and 2) effects of local treatment can be measured individually for each supplying coronary vessel. A hemodynamically relevant stenosis was created by implantation of a tapered stent at day 0 (d0) in the left circumflex artery (LCX), followed by complete arterial occlusion at day 14 (d14). Fluorescent microspheres were injected for demarcation of perfusion territories at each time point. Three and four weeks after induction of stenosis, collateral conductance measurements were performed for each coronary artery separately using differently labeled fluorescent microspheres. Postmortem angiography after acute LCX occlusion confirmed the presence of preexistent coronary anastomoses in the pig. The tapered stent created a hemodynamically significant stenosis immediately postplacement (fractional flow reserve, 0.70 ± 0.03). Between day 21 and 28, collateral conductance significantly increased in both the left anterior descending (LAD) and the right coronary artery (RCA)-supplied, collateral-dependent territories (LAD d21, 0.77 ± 0.14; LAD d28, 1.35 ± 0.12; RCA d21, 0.88 ± 0.29; RCA d28, 1.70 ± 0.16 ml · min(-1) · g(-1) · 100 mmHg(-1)), indicating collateral artery growth. We here describe a new translational minimally invasive model of coronary collateral artery growth in pigs, according to a defined protocol of LCX-stenosis and subsequent occlusion, allowing preclinical evaluation of arteriogenic therapies.     

Angiogenic strategy for human ischemic heart disease: Brief overview

In the Western World ischemic coronary disease is the leading cause of morbidity and mortality. Therapeutic approaches mostly aim to restore flow to a localized segment by angioplasty or bypass surgery. Therapeutic angiogenesis and or arteriogenesis describes a strategy where blood vessel formation is induced for the purposes of treating and/or preventing ischemic disease. At present, at least 17 clinical trials of myocardial angiogenesis have been presented involving over 900 patients. Therapeutic angiogenesis makes use of the administration of angiogenic growth factor protein or gene to promote the development of endogenous collateral vessels in ischemic myocardium. Most recently, interest has grown in the potential angiogenesis effects of cell therapy—such as autologous bone marrow cells or cultured stem cells—and there are now several groups initiating phase I/II trials in this area. (Mol Cell Biochem 264: 143–149, 2004)     

Autologous mesenchymal stem cell transplantation induce VEGF and neovascularization in ischemic myocardium

Neovascularization induced by vascular endothelial growth factor (VEGF) represents an appealing approach for treating ischemic heart disease. However, VEGF therapy has been associated with transient therapeutic effects and potential risk for hemangioma growth. Adult mesenchymal stem cells (MSCs) derived from bone marrow are a promising source for tissue regeneration and repair. In order to achieve a safe and persistent angiogenic effect, we have explored the potential of autologous MSCs transplantation to enhance angiogenesis and cardiac function of ischemic hearts. One week after myocardial infarction induced by occlusion of left anterior descending artery, autologous MSCs expanded in vitro was administrated intramyocardially into the infarct area of the same donor rats. By 2 months, MSCs implantation significantly elevated VEGF expression levels, accompanied by increased vascular density and regional blood flow in the infarct zone. The neovascularization resulted in a decreased apoptosis of hypertrophied myocytes and markedly improved the left ventricular contractility (ejection fraction: 79.9+/-7.6% vs. 37.2+/-6.9% in control animals). Therefore, mechanisms underlying MSCs improvement of cardiac functions may involve neovascularization induced by differentiation of MSCs to endothelial cells and para-secretion of growth factors, in addition to the apoptosis reduction and previously reported cardiomyocytes regeneration. Two months after cell transplantation, there are significant improvement of left ventricular function. Hence, autologous MSCs transplantation may represent a promising therapeutic strategy free of ethical concerns and immune rejection, for neovascularization in ischemic heart diseases.     

Norepinephrine of the rat myocardium during repeated ischemia

Character of tissue changes as well as their reversibility could vary depending on the duration of myocardial ischemia. Long (over 30 min) ischemia leads to a massive release of myocardial interstitial norepinephrine. We tried to investigate changes in the myocardial sympathetic system produced by a relatively long episode of ischemia-repeperfusion. Myocardial norepinephrine has been collected by means of microdialysis probe during repeated occlusions of the left descending coronary artery. It was shown that long episode of occulusion-reperfusion resulted in suppression of massive norepinephrine release in response to second (test) occlusion. The features of norepinephrine release during successive occlusions make it possible to associate this process with the reversibility of the ischemic tissue damages.     

Autologous stem cell transplantation for myocardial repair

Current therapies for heart failure due to transmural left ventricular (LV) infarction are limited. We have developed a novel patch method for delivering autologous bone marrow stem cells to sites of myocardial infarction for the purpose of improving LV function and preventing LV aneurysm formation. The patch consisted of a fibrin matrix seeded with autologous porcine mesenchymal stem cells labeled with lacZ. We applied this patch to a swine model of postinfarction LV remodeling. Myocardial infarction was produced by using a 60-min occlusion of the left anterior descending coronary artery distal to the first diagonal branch followed by reperfusion. Results were compared between eight pigs with stem cell patch transplantation, six pigs with the patch but no stem cells (P), and six pigs with left anterior descending coronary artery ligation alone (L). Magnetic resonance imaging data collected 19 +/- 1 days after the myocardial infarction indicated a significant increase of LV systolic wall thickening fraction in the infarct zone of transplanted hearts compared with P or L hearts. Blue X-gal staining was observed in the infarcted area of transplanted hearts. PCR amplification of specimens from the X-gal-positive area revealed the Ad5 RSV-lacZ vector fragment DNA sequence. Light microscopy demonstrated that transplanted cells had differentiated into cells with myocyte-like characteristics and a robust increase of neovascularization as evidenced by von Willebrand factor-positive angioblasts and capillaries in transplanted hearts. Thus this patch-based autologous stem cell procedure may serve as a therapeutic modality for myocardial repair.     

Reactive oxygen and NF-kappaB in VEGF-induced migration of human vascular smooth muscle cells.

Migration and proliferation of vascular smooth muscle cells (VSMC) contribute to angiogenesis and the lesions of atherosclerosis. Since, vascular endothelial growth factor (VEGF) is overexpressed by VSMC in intima of atherosclerotic human coronary arteries, we determined if VEGF could stimulate VSMC migration and the intracellular signals involved. VEGF induced VSMC migration but had no significant activity on proliferation. VEGF increased intracellular reactive oxygen species (ROS), NF-kappaB activation and IL-6 expression. Blockade of the generation of intracellular ROS by antioxidants inhibited VEGF-induced NF-kappaB activation, IL-6 expression, and cell migration indicating that generation of ROS was required for NF-kappaB activation and the chemotactic activity of VEGF. Expression of a mutated, nondegradable form of inhibitor of NF-kappaB (IkappaB-alphaM) suppressed VEGF-triggered activation of NF-kappaB and upregulation of IL-6 as well as VSMC migration. Neutralization of IL-6 by its antibody significantly attenuated the migration stimulated by VEGF. Collectively, our data provide the first evidence that intracellular ROS and NF-kappaB are required for VEGF-mediated smooth muscle cell migration. Further, IL-6 induced by VEGF is involved in the ability of the growth factor to stimulate migration.     

Therapeutic myocardial angiogenesis with vascular endothelial growth factors

Emerging evidence has shown that administration of angiogenic growth factors, either as recombinant protein or by gene transfer, can augment tissue perfusion through neovascularization in animal models of myocardial and hindlimb ischemia. Many cytokines have angiogenic activity; one of those that have been best studied in animal models and clinical trials is vascular endothelial growth factor (VEGF). VEGF has been known to be a key regulator of physiologic and pathologic angiogenesis associated with tumor. Recently the effect of VEGF is not restricted to the direct angiogenic effect in vivo but includes mobilization of bone-marrow-derived endothelial progenitor cells and augmentation of postnatal vasculogenesis in situ. Clinical trials of therapeutic angiogenesis with VEGF in patients with end-stage coronary artery disease have shown increases in exercise time and reductions in anginal symptoms and have provided objective evidence of improved perfusion and left ventricular function. Larger scale placebo-controlled trials with recombinant protein (rhVEGF₁₆₅) have been limited to intracoronary and intravenous administration and have shown favorable trends in exercise time and angina frequency. Small-scale, placebo-controlled, randomized clinical trials of gene transfer (phVEGF-2) via thoracotomy or percutaneous intramyocardial delivery demonstrated significant improvement of both subjective symptoms and objective measures of myocardial ischemia. Both therapeutic modalities appear to be safe and well tolerated. Further studies are required to determine the optimal dose, formulation, route of administration, and combinations of growth factors and the utility of adjunctive endothelial progenitor cell or other stem cell supplementation, to provide safe and effective therapeutic myocardial neovascularization. (Mol Cell Biochem 264: 63–74, 2004)     

Elabela gene therapy promotes angiogenesis after myocardial infarction

This study was aimed at investigating whether Elabela (ELA) gene therapy can promote angiogenesis in the treatment of myocardial infarction (MI). The fusion expression plasmid pAAV-3 × Flag/ELA-32 was successfully constructed using molecular cloning technique. The model of acute MI was established by ligating the left anterior descending coronary artery in mice. Adeno-associated virus serotype 9 (AAV9) was injected into the surrounding myocardium and tail vein immediately after the model was established. AAV was injected again from the tail vein one week later. Compared with the MI+PBS (control) group, the serum N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration, and the values of left ventricular end-diastolic diameter (LVDd) and left ventricular end-systolic diameter (LVDs) of the MI+AAV-ELA (gene therapy) group were significantly decreased, while the value of left ventricular ejection fraction was significantly increased at 2 and 4 weeks after operation. Compared with the control group, the expression of CD105 and vWF and the percentage of CD31- and Ki67–co-positive cells were significantly increased in the gene therapy group. Moreover, the expressions of apelin peptide jejunum (APJ) receptor, vascular endothelial growth factor (VEGF), VEGFR2, Jagged1 and Notch3 in the heart tissue around the infarction were up-regulated in mice with gene therapy. The results suggest that ELA activates VEFG/VEGFR2 and Jagged1/Notch3 pathways through APJ to promote angiogenesis after myocardial infarction. ELA gene therapy may be used in the treatment of ischaemic cardiomyopathy in future.     

Non-linear dynamic analysis of the cardiac rhythm during transient myocardial ischemia.

Coronary artery occlusions related to myocardial ischemia drive cardiac control system reactions that may lead to heart failure. The purpose of this study was to assess the autonomic nervous system (ANS) response during prolonged percutaneous transluminal coronary angioplasty (PTCA). Continuous ECG data were acquired from 50 patients before and during PTCA, with occlusions in the left anterior descending, left circumflex or right coronary artery. Heart rate variability (HRV) was analyzed for 3-min segments of the R-R interval signal obtained from ECG data. The ANS behavior was evaluated by HRV analysis using fractal-like indices. The fractal scalar exponent alpha(1) and power-law slope beta decreased considerably during PTCA. This indicates that significant reactions of autonomic control of the heart rate occurred during coronary artery occlusions, with a reduction in complexity of the ANS.     

Role of MMPs and plasminogen activators in angiogenesis after transmyocardial laser revascularization in dogs

We examined the role of matrix metalloproteinases (MMPs), tissue inhibitors of MMP (TIMPs), and plasminogen activator (PA) in transmyocardial laser revascularization (TMLR)-induced angiogenesis. TMLR was accomplished with a carbon dioxide laser in seven dogs whose left anterior descending coronary artery (LAD) was ligated. Seven control dogs underwent only LAD ligation, and four dogs underwent a sham operation, consisting only of a left thoracotomy. Two weeks later, transmural myocardial samples were harvested from the distributions of the LAD and the left circumflex artery for substrate zymography, immunohistochemical staining, and in situ zymography. MMP-1, MMP-2, TIMP-1, TIMP-2, and urokinase-type PA levels in the distribution of the LAD were higher in the laser group than in the control or sham group. Counts of von Willebrand factor-positive microvessels and smooth muscle alpha-actin-positive arterioles demonstrated that the angiogenesis and ateriogenesis was promoted in the laser group and correlated directly with the number of MMP-stained microvessels. We conclude that TMLR induces the expression of MMPs, TIMPs, and urokinase-type PA and that these proteinases play an important role in angiogenesis after TMLR.     

Haptoglobin expression and activity during coronary collateralization

Coronary collateral development relies on the coordinated secretion of growth factors. However, alone they are insufficient for permanent collateral growth. We utilized proteomics to identify other important proteins in the extracellular environment that could facilitate collateralization. Chronically instrumented dogs developed coronary collaterals by the repetitive occlusion method. Subendocardial (0.19 +/- 0.04, 0.27 +/- 0.06, 0.48 +/- 0.10, and 0.81 +/- 0.11 ml x min(-1) x g(-1) on days 1, 7, 14, and 21, respectively) and subepicardial (0.14 +/- 0.01, 0.36 +/- 0.06, 0.51 +/- 0.07, and 0.71 +/- 0.08 ml x min(-1) x g(-1) on days 1, 7, 14, and 21, respectively) blood flow increased in animals subjected to repetitive occlusion. Sham animals exhibited no changes in blood flow. Myocardial interstitial fluid (MIF) from both groups was analyzed by two-dimensional electrophoresis with matrix-assisted laser desorption/ionization time-of-flight identification. The acute-phase protein haptoglobin was identified in the group subjected to repetitive occlusion. ELISA of MIF showed haptoglobin to be elevated at all time points of collateral development compared with sham, with maximal production on day 7. Purified haptoglobin dose dependently stimulated endothelial cells to form tubes and vascular smooth muscle cells to migrate. Purified haptoglobin did not stimulate proliferation of either cell type. The relative contribution of haptoglobin to the chemotactic properties of MIF was tested using a neutralizing antibody. Neutralized MIF could not stimulate smooth muscle cells to migrate at any time during collateral development. Endothelial cell tube formation was inhibited after the midpoint of collateralization. Therefore, the acute-phase protein haptoglobin plays a critical role during coronary collateralization.     

Transcoronary sinus delivery of autologous bone marrow and angiogenesis in pig models with myocardial injury

Purpose: The aim of the investigation is to study myocardial injury on pig model with two objectives: (1) feasibility of stimulating angiogenesis with fresh autologous bone marrow; (2) administration of the same fresh autologous bone marrow via coronary sinus with transitory occlusion. Methods: A controlled study was done in animal model with three phases, in a study group of 12 pigs (bone marrow administration) as well as in control group of 4 pigs (saline administration). Phase 1—production of coronary stenosis and myocardial injury; Phase 2—two weeks later, administration of bone marrow through coronary sinus with 10 min occlusion in the study group and saline solution in the control group. Phase 3—two weeks later, histological staining with hematoxylin–eosin and inmunohistochemical staining with monoclonal antibody for smooth muscle α-actin were conducted on both study and control groups. Results: The percentage of angionenesis observed in the study group was 91% and 0% in control group. Counting of positive actin in affected and control areas showed statistically significant differences in relation to both groups: study group (1.37 vs. 0.79) and control group (0.47 vs. 0.51). The percentage of mononuclear immature cells observed in the myocardium in the study group was 25% and in the control group was 0%. There was no increment in the coronary collateral circulation when comparing coronary angiography. Conclusions: Autologous bone marrow in animal model with experimental myocardial injury enhances angiogenesis, as well as vessels with smooth muscles. The transitory occlusion of the coronary sinus might be an effective way to administer cells as those from the bone marrow.     

Effects of adenosine and acadesine on interstitial nucleosides and myocardial stunning in the pig.

5-Amino-4-imidazolecarboxamide riboside (AICAr) or acadesine has been proposed to exert cardioprotection by enhancing adenosine production in ischemic myocardium. However, there are conflicting reports on acadesine's effects in ischemic myocardium and few studies in which myocardial adenosine levels have been measured. The purpose of this study was to determine whether acadesine increases interstitial fluid adenosine levels and attenuates myocardial stunning or potentiates the effects of adenosine in the intact pig. In pentobarbital-anesthetized pigs, myocardial stunning was induced by 10 min left anterior descending coronary artery occlusion and 90 min reperfusion. Regional ventricular function was assessed by measuring systolic wall thickening, and interstitial nucleosides were estimated by cardiac microdialysis. Control hearts were compared with hearts treated with acadesine, adenosine, and adenosine plus acadesine. Adenosine pretreatment (100 microg x kg(-1) x min(-1), intracoronary) immediately prior to ischemia increased interstitial adenosine levels 9-fold and improved postischemic functional recovery from a control value of 17.6 +/- 4.1% to 43.6 +/- 3.4% of preischemic systolic wall thickening. In contrast, acadesine (20 mg/kg i.v. bolus 10 min prior to ischemia + 0.5 mg x kg (-1) x min(-1), i.v. infusion through 60 min reperfusion) had no effect on interstitial fluid adenosine levels or the recovery of regional function (21.5 +/- 5.9% recovery), nor were the functional effects of adenosine potentiated by acadesine. These findings indicate that acadesine does not enhance myocardial adenosine levels, attenuate myocardial stunning, or potentiate the cardioprotective effects of adenosine in the pig.