Karola Trescher

Colony-stimulating factor-1 transfection of myoblasts improves the repair of failing myocardium following autologous myoblast transplantation

AIMS Skeletal myoblasts are used in repair of ischaemic myocardium. However, a large fraction of grafted myoblasts degenerate upon engraftment. Colony-stimulating factor-1 (CSF-1) accelerates myoblast proliferation and angiogenesis. We hypothesized that CSF-1 overexpression improves myoblast survival and cardiac function in ischaemia-induced heart failure. METHODS AND RESULTS Three weeks following myocardial infarction, rats developed heart failure and received intramyocardial injections of mouse CSF-1-transfected or untransfected primary autologous rat myoblasts, recombinant human CSF-1, mouse CSF-1 expressing plasmids, or culture medium. Tissue gene and protein expression was measured by quantitative RT-PCR (reverse transcription-polymerase chain reaction) and western blotting. Fluorescence imaging and immunocytochemistry were used to analyse myoblasts, endothelial cells, macrophages, and infarct wall thickening. Electrocardiograms were recorded online using a telemetry system. Left ventricular function was assessed by echocardiography over time, and improved significantly only in the CSF-1-overexpressing myoblast group. CSF-1-overexpression enhanced myoblast numbers and was associated with an increased infarct wall thickness, enhanced angiogenesis, increased macrophage recruitment and upregulated matrix metalloproteases (MMP)-2 and -12 in the zone bordering the infarction. Transplantation of CSF-1-overexpressing myoblasts did not result in major arrhythmias. CONCLUSION Autologous intramyocardial transplantation of CSF-1 overexpressing myoblasts might be a novel strategy in the treatment of ischaemia-induced heart failure.

Improved myocardial protection in the failing heart by selective endothelin-A receptor blockade

OBJECTIVE Ischemia/reperfusion injury caused by cardioplegic arrest is still a major challenge in patients with reduced left ventricular function. We investigated the effect of chronic versus acute administration of the selective endothelin-A receptor antagonist (ERA) TBC-3214Na during ischemia/reperfusion in failing hearts. METHODS Male Sprague-Dawley rats underwent coronary ligation. Three days after myocardial infarction (MI), 19 randomly assigned animals (ERA chronic) were administered TBC-3214Na continuously with their drinking water, 29 MI rats received placebo, and 3 rats died during the observation period. Six weeks after infarction, hearts were evaluated in a blood-perfused working heart model during 60 minutes of ischemia and 30 minutes of reperfusion. In 14 MI rats, TBC-3214Na (ERA acute) was added to the cardioplegic solution during ischemia. Thirteen MI rats served as control. RESULTS At a similar infarct size, postischemic recovery of cardiac output (ERA chronic: 91% +/- 10%, ERA acute: 86% +/- 11% vs control: 52% +/- 15%; P < .05) and external heart work (ERA chronic: 90% +/- 10%, ERA acute: 85% +/- 13% vs control: 51% +/- 17%; P < .05) was significantly enhanced in both TBC-3214Na-treated groups whereas recovery of coronary flow was only improved in ERA acute rats (ERA acute: 121% +/- 23% vs ERA chronic: 75% +/- 13%; control: 64% +/- 15%; P < .05). Blood gas measurements showed enhanced myocardial oxygen delivery and consumption with acute TBC-3214Na therapy. Additionally, high-energy phosphates (phosphocreatine) were significantly higher and transmission electron microscopy revealed less ultrastructural damage under acute TBC-3214Na administration. CONCLUSION Acute endothelin-A receptor blockade is superior to chronic blockade in attenuating ischemia/reperfusion injury in failing hearts. Therefore, acute endothelin-A receptor blockade might be an interesting option for patients with heart failure undergoing cardiac surgery.

Myofilament protein carbonylation contributes to the contractile dysfunction in the infarcted LV region of mouse hearts

AIMS The region-specific mechanical function of left ventricular (LV) murine cardiomyocytes and the role of phosphorylation and oxidative modifications of myofilament proteins were investigated in the process of post-myocardial infarction (MI) remodelling 10 weeks after ligation of the left anterior descending (LAD) coronary artery. METHODS AND RESULTS Permeabilized murine cardiomyocytes from the remaining anterior and a remote non-infarcted inferior LV area were compared with those of non-infarcted age-matched controls. Myofilament phosphorylation, sulfhydryl (SH) oxidation, and carbonylation were also assayed. Ca(2+) sensitivity of force production was significantly lower in the anterior wall (pCa50: 5.81 ± 0.03, means ± SEM, at 2.3 µm sarcomere length) than that in the controls (pCa50: 5.91 ± 0.02) or in the MI inferior area (pCa50: 5.88 ± 0.02). The level of troponin I phosphorylation was lower and that of myofilament protein SH oxidation was higher in the anterior location relative to controls, but these changes did not explain the differences in Ca(2+) sensitivities. On the other hand, significantly higher carbonylation levels, [e.g. in myosin heavy chain (MHC) and actin] were observed in the MI anterior wall [carbonylation index (CI), CIMHC: 2.06 ± 0.46, CIactin: 1.46 ± 0.18] than in the controls (CI: 1). In vitro Fenton-based myofilament carbonylation in the control cardiomyocytes also decreased the Ca(2+) sensitivity of force production irrespective of the phosphorylation status of the myofilaments. Furthermore, the Ca(2+) sensitivity correlated strongly with myofilament carbonylation levels in all investigated samples. CONCLUSION Post-MI myocardial remodelling involves increased myofibrillar protein carbonylation and decreased Ca(2+) sensitivity of force production, leading potentially to contractile dysfunction in the remaining cardiomyocytes of the infarcted area.

Type A dissection and chronic dilatation: tenascin-C as a key factor in destabilization of the aortic wall

OBJECTIVES Tenascin-C plays an important role in myocardial and vascular remodelling. We hypothesized that tenascin-C is a key factor in the development of degenerative disease of the ascending aorta, leading to chronic dilatation and acute aortic dissection. METHODS Ascending aortic wall specimens were obtained during surgery for chronic dilatation (n=52) and acute Type A dissection (n=30). Patients (n=12) undergoing aortic valve replacement served as controls. Tenascin-C expression was evaluated by immunostaining and semi-quantitatively assessed using the ImageJ software. TN-C levels in peripheral blood were determined by enzyme-linked immunosorbent assay. RESULTS Histological examination showed a clear difference between chronic dilatation and acute dissection. In chronic dilatation, tenascin-C staining was homogenously distributed throughout the media parallel to vascular smooth muscle cells. In acute dissection, a strong staining with a heterogenous and spotty distribution was detected. Control aortas showed no tenascin-C staining. Tenascin-C expression was significantly higher in Type-A dissection compared with chronic dilatation. This was accompanied by a significant elevation of tenascin-C levels in peripheral blood in acute dissection. There was no statistical correlation between the tenascin-C level in peripheral blood and the aortic diameter either in dissection or in dilatation. CONCLUSIONS Tenascin-C is a marker of progressive destabilization of the aortic wall independent of size in chronic dilatation and acute dissection. Therefore, it might be a valuable tool in guiding intervention strategies in patients with disease of the ascending aorta.

Introducing a mouse model of brain death

Experimental animal models of brain death increasing intracranial pressure (ICP) by inflating an intracranial placed balloon-catheter are well established and used in transplant-associated studies. Our aim was to develop an experimental mouse model of brain death (BD) and to compare explosive and gradual brain death induction under ICP monitoring. We therefore induced BD in female OF-1 mice by injecting 40 microl saline every 5 min into an intracranial placed balloon increasing ICP rapidly [BD ex, n=7], or gradually [BD grad, n=7] with 20 microl volume every 5 min under electroencephalogram (EEG) and ICP monitoring until BD occurred. The major criterion for BD was a flat-line-EEG, confirmed by cessation of spontaneous respiration and maximally dilated and fixed pupils. ICP, central activity and heart rate were continuously monitored during the entire 6h follow-up. In sham-operated controls [control, n=7] a burr hole was drilled but no balloon inserted. The BD groups showed equal ICP levels at the time of BD. Both groups had increased heart rates (HR) 15 min after BD, HR decreased to 402+/-29.39 bpm (beats per minute) [BD ex] and 409.33+/-26.46 bpm [BD grad] (n.s. vs. control) by 30 min after the inflation of the balloon, but only BD ex showed a significant decrease in HR compared to control, progressively decreasing thereafter. On the basis of these results, we conclude that the mouse model of brain death can be performed in a standardized, reproducible and successful way.

The nitric oxide donor, S-nitroso human serum albumin, as an adjunct to HTK-N cardioplegia improves protection during cardioplegic arrest after myocardial infarction in rats

OBJECTIVES Currently available cardioplegic solutions provide excellent protection in patients with normal surgical risk; in high-risk patients, however, such as in emergency coronary artery bypass surgery, there is still room for improvement. As most of the cardioplegic solutions primarily protect myocytes, the addition of substances for protection of the endothelium might improve their protective potential. The nitric oxide donor, S-nitroso human serum albumin (S-NO-HSA), which has been shown to prevent endothelial nitric oxide synthase uncoupling, was added to the newly developed histidine-tryptophan-ketoglutarat (HTK-N) cardioplegia in an isolated heart perfusion system after subjecting rats to acute myocardial infarction (MI) and reperfusion. METHODS In male Sprague-Dawley rats, acute MI was induced by ligation for 1 h of the anterior descending coronary artery. After 2 h of in vivo reperfusion hearts were evaluated on an isolated erythrocyte-perfused working heart model. Cold ischaemia (4°C) for 60 min was followed by 45 min of reperfusion. Cardiac arrest was induced either with HTK (n = 10), HTK-N (n = 10) or HTK-N + S-NO-HSA (n = 10). In one group (HTK-N + S-NO-HSA plus in vivo S-NO-HSA; n = 9) an additional in vivo infusion of S-NO-HSA was performed. RESULTS Post-ischaemic recovery of cardiac output (HTK: 77 ± 4%, HTK-N: 86 ± 7%, HTK-N + S-NO-HSA: 101 ± 5%, in vivo S-NO-HSA: 93 ± 8%), external heart work (HTK: 79 ± 5%, HTK-N: 83 ± 3%, HTK-N + S-NO-HSA: 101 ± 8%, in vivo S-NO-HSA: 109 ± 13%), coronary flow (HTK: 77 ± 4%, HTK-N: 94 ± 6%, HTK-N + S-NO-HSA: 118 ± 15%, in vivo S-NO-HSA: 113 ± 3.17%) [HTK-N + S-NO-HSA vs HTK P < 0.001; HTK-N + S-NO-HSA vs HTK-N P < 0.05] and left atrial diastolic pressure (HTK: 122 ± 31%, HTK-N: 159 ± 43%, HTK-N + S-NO-HSA: 88 ± 30, in vivo S-NO-HSA: 62 ± 10%) [HTK-N + S-NO-HSA vs HTK P < 0.05; in vivo S-NO-HSA vs HTK-N P < 0.05] were significantly improved in both S-NO-HSA-treated groups compared with HTK and HTK-N, respectively. This was accompanied by better preservation of high-energy phosphates (adenosine triphosphate; energy charge) and ultrastructural integrity on transmission electron microscopy. However, no additional benefit of in vivo S-NO-HSA infusion was observed. CONCLUSIONS Addition of the NO donor, S-NO-HSA refines the concept of HTK-N cardioplegia in improving post-ischaemic myocardial perfusion. HTK-N with S-NO-HSA is a possible therapeutic option for patients who have to be operated on for acute MI.

Short-term clinical outcomes between intermittent cold versus intermittent warm blood cardioplegia in 2200 adult cardiac surgery patients.

BACKGROUND Aim of the present study was to compare clinical outcome of intermittent cold (ICC) versus intermittent warm (IWC) blood cardioplegia in different cardiosurgical procedures. METHODS Two thousand one hundred and eighty-eight patients were retrospectively divided into 5 groups: isolated coronary artery bypass surgery (CABG; N.=1203), isolated aortic valve surgery (AVR; N.=374), isolated mitral valve surgery (MVR; N.=151), combined AVR+CABG (N.=390), and combined MVR+CABG (N.=70). Myocardial protection was performed by ICC (N.=1578) or IWC (N.=610) blood cardioplegia. In logistic regression models the effect of cardioplegia on 30-day mortality, IABP/ECLS (intraaortic balloon-pump/extracorporal life support) implantation, transient neurological deficit, stroke, renal failure, new-onset atrial fibrillation, and troponin T release was estimated. Potential modifications of the effect of cardioplegia by logistic EuroSCORE, cross-clamping time, ejection fraction, and op-status elective versus urgent/emergent were investigated. RESULTS There were no statistically significant differences between ICC and IWC regarding 30-day mortality (odds ratio [OR]=0.70; 95% CI: 0.39-1.23; P=0.219), IABP/ECLS support (OR=0.60; 95% CI: 0.23-1.55; P=0.294), transient neurological deficit (OR=0.90; 95% CI: 0.65-1.24; P=0.541), stroke (OR=0.79; 95% CI: 0.40-1.54; P=0.495), renal failure (OR=1.07; 95% CI: 0.57-1.99; P=0.825), and atrial fibrillation (OR=0.96; 95% CI: 0.77-1.18; P=0.713) across all 5 groups. Troponin t release was significantly higher in ICC compared to IWC (by 0.029±0.015 ng/mL; P=0.046) in univariate analysis; this effect was lowered by risk-factor adjustment and lost statistical significance. The effect of cardioplegia was not significantly different between groups. In urgent/emergent surgery ICC resulted in a significantly higher 30-day mortality (OR=3.03; P=0.024) compared to IWC. CONCLUSIONS The comparison of IWC and ICC blood cardioplegia in different cardiosurgical procedures showed no statistical significant difference in myocardial protection. The use of ICC, however, appeared overall associated with a slightly better clinical outcome except in patients undergoing urgent/emergent CABG where IWC led to a reduction in 30-day-mortality.

SiNiTang ? A Traditional Chinese Herbal Remedy Improves Cardiac Function Post-MI

SiNiTang is a well known traditional Chinese herbal remedy. It is used to treat cold extremities, weak pulse and lethargy: Symptoms that correspond with myocardial infarction and heart failure in western medicine. To examine potential beneficial effects on post-MI remodeling, a modified SiNiTang formula was tested using a well established model of myocardial infarction in Rats. Application of SiNiTang significantly reduced left ventricular dilation and thus preserved left ventricular function. However, it did not affect the hypertrophic response. Exploratory histopathological examination revealed better vascularization of infarct and peri-infarct areas in SiNiTang treated animals compared to placebo. HUVEC cells were treated with SiNiTang showed increased proliferation and tube formation. SiNiTang attenuates ventricular dilation post-MI and increases neoangiogenesis.

In vivo and ex vivo functional characterization of left ventricular remodelling after myocardial infarction in mice

The interest in cardiac remodelling (REM) has steadily increased during recent years. The aim of this study was to functionally characterize REM following myocardial infarction (MI) in mice using high‐end in vivo and ex vivo methods.

Protection of the Failing Heart

In the developed world, heart failure (HF) is the only cardiovascular disease that is steadily increasing. Both in Europe and the United States about five million people live with the diagnosis of HF, and about 400,000 patients are newly diagnosed every year. Several epidemiological and demographic factors contribute to this trend (Hunt et al.). (a) The development of HF goes parallel with the rise in life expectancy. HF is clearly a disease of the elderly because 80% of the patients admitted to hospital with the diagnosis of HF are older than 65 years (Katz and Konstam ). (b) Improved treatment regimens of acute myocardial infarction (MI) increase survival. Consequently, the survivors are more likely to develop HF due to postMI remodelling later in their life (Opie (c) A general increase in pharmacological and non-pharmacological treatment modalities heightens the number of patients living with HF and/or reaching later stages of HF.