Myogenic Reprogramming of Bone Marrow Derived Cells in a W41Dmdmdx Deficient Mouse Model

Lack of expression of dystrophin leads to degeneration of muscle fibers and infiltration of connective and adipose tissue. Cell transplantation therapy has been proposed as a treatment for intractable muscle degenerative disorders. Several reports have demonstrated the ability of bone-marrow derived cells (BMDC) to contribute to non-haematopoietic tissues including epithelium, heart, liver, skeletal muscle and brain following transplantation by means of fusion and reprogramming. A key issue is the extent to which fusion and reprogramming can occur in vivo, particularly under conditions of myogenic deterioration

Brain natriuretic peptide is related to diastolic dysfunction whereas urinary albumin excretion rate is related to left ventricular mass in asymptomatic type 2 diabetes patients

<p>Abstract</p> <p>Background</p> <p>The aims of this study were to estimate the prevalence of left ventricular systolic (LVSD) and diastolic (LVDD) dysfunction, and to test if BNP and urinary albumin excretion rate (AER) are related to LVSD, LVD and left ventricular mass (LVM) in asymptomatic type 2 diabetes patients.</p> <p>Methods</p> <p>Presence of LVSD, LVDD and LVM, determined with echocardiography, was related to levels of BNP and AER in 153 consecutive asymptomatic patients with type 2 diabetes.</p> <p>Results</p> <p>LVSD was present in 6.1% of patients whereas 49% (29% mild, 19% moderate and 0.7% severe) had LVDD and 9.4% had left ventricular hypertrophy. Increasing age (P < 0.0001) was the only independent variable related to mild LVDD whereas increasing BNP (P = 0.01), systolic blood pressure (P = 0.01), age (P = 0.003) and female gender (P = 0.04) were independent determinants of moderate to severe LVDD. AER (P = 0.003), age (P = 0.01) and male gender (P = 0.006) were directly and independently related to LVM.</p> <p>Conclusion</p> <p>About half of asymptomatic type 2 diabetes patients have LVDD. Of those, more than one third display moderate LVDD pattern paralleled by increases in BNP, suggesting markedly increased risk of heart failure, especially in females, whereas AER and male sex are related to LVM.</p

Decreased inducibility of TNF expression in lipid-loaded macrophages

BACKGROUND: Inflammation and immune responses are considered to be very important in the pathogenesis of atherosclerosis. Lipid accumulation in macrophages of the arterial intima is a characteristic feature of atherosclerosis which can influence the inflammatory potential of macrophages. We studied the effects of lipid loading on the regulation of TNF expression in human monocyte-derived macrophages. RESULTS: In macrophages incubated with acetylated low density lipoprotein (ac-LDL) for 2 days, mRNA expression of TNF in cells stimulated with TNF decreased by 75%. In cell cultures stimulated over night with IL-1β, lipid loading decreased secretion of TNF into culture medium by 48%. These results suggest that lipid accumulation in macrophages makes them less responsive to inflammatory stimuli. Decreased basal activity and inducibility of transcription factor AP-1 was observed in lipid-loaded cells, suggesting a mechanism for the suppression of cytokine expression. NF-κB binding activity and inducibility were only marginally affected by ac-LDL. LDL and ac-LDL did not activate PPARγ. In contrast, oxidized LDL stimulated AP-1 and PPARγ but inhibited NF-κB, indicating that the effects of lipid loading with ac-LDL were not due to oxidation of lipids. CONCLUSIONS: Accumulation of lipid, mainly cholesterol, results in down-regulation of TNF expression in macrophages. Since monocytes are known to be activated by cell adhesion, these results suggest that foam cells in atherosclerotic plaques may contribute less potently to an inflammatory reaction than newly arrived monocytes/macrophages

Cardiovascular magnetic resonance of the myocardium at risk in acute reperfused myocardial infarction: comparison of T2-weighted imaging versus the circumferential endocardial extent of late gadolinium enhancement with transmural projection

<p>Abstract</p> <p>Background</p> <p>In the situation of acute coronary occlusion, the myocardium supplied by the occluded vessel is subject to ischemia and is referred to as the myocardium at risk (MaR). Single photon emission computed tomography has previously been used for quantitative assessment of the MaR. It is, however, associated with considerable logistic challenges for employment in clinical routine. Recently, T2-weighted cardiovascular magnetic resonance (CMR) has been introduced as a new method for assessing MaR several days after the acute event. Furthermore, it has been suggested that the endocardial extent of infarction as assessed by late gadolinium enhanced (LGE) CMR can also be used to quantify the MaR. Hence, we sought to assess the ability of endocardial extent of infarction by LGE CMR to predict MaR as compared to T2-weighted imaging.</p> <p>Methods</p> <p>Thirty-seven patients with early reperfused first-time ST-segment elevation myocardial infarction underwent CMR imaging within the first week after percutaneous coronary intervention. The ability of endocardial extent of infarction by LGE CMR to assess MaR was evaluated using T2-weighted imaging as the reference method.</p> <p>Results</p> <p>MaR determined with T2-weighted imaging (34 ± 10%) was significantly higher (p < 0.001) compared to the MaR determined with endocardial extent of infarction (23 ± 12%). There was a weak correlation between the two methods (r²= 0.17, p = 0.002) with a bias of -11 ± 12%. Myocardial salvage determined with T2-weighted imaging (58 ± 22%) was significantly higher (p < 0.001) compared to myocardial salvage determined with endocardial extent of infarction (45 ± 23%). No MaR could be determined by endocardial extent of infarction in two patients with aborted myocardial infarction.</p> <p>Conclusions</p> <p>This study demonstrated that the endocardial extent of infarction as assessed by LGE CMR underestimates MaR in comparison to T2-weighted imaging, especially in patients with early reperfusion and aborted myocardial infarction.</p

Myocardium at risk by magnetic resonance imaging: head-to-head comparison of T2-weighted imaging and early gadolinium enhanced steady state free precession

AIMS: To determine the myocardial salvage index, the extent of infarction needs to be related to the myocardium at risk (MaR). Thus, the ability to assess both infarct size and MaR is of central clinical and scientific importance. The aim of the present study was to explore the relationship between T2-weighted cardiac magnetic resonance (CMR) and contrast-enhanced steady-state free precession (CE-SSFP) CMR for the determination of MaR in patients with acute myocardial infarction. METHODS AND RESULTS: Twenty-one prospectively included patients with first-time ST-elevation myocardial infarction underwent CMR 1 week after primary percutaneous coronary intervention. For the assessment of MaR, T2-weighted images were acquired before and CE-SSFP images were acquired after the injection of a gadolinium-based contrast agent. For the assessment of infarct size, late gadolinium enhancement images were acquired. The MaR by T2-weighted imaging and CE-SSFP was 29 ± 11 and 32 ± 12% of the left ventricle, respectively. Thus, the MaR with T2-weighted imaging was slightly smaller than that by CE-SSFP (-3.0 ± 4.0%; P < 0.01). There was a significant correlation between the two MaR measures (r(2)= 0.89, P < 0.01), independent of the time after contrast agent administration at which the CE-SSFP was commenced (2-8 min). CONCLUSION: There is a good agreement between the MaR assessed by T2-weighted imaging and that assessed by CE-SSFP in patients with reperfused acute myocardial infarction 1 week after the acute event. Thus, both methods can be used to determine MaR and myocardial salvage at this point in time

Infarct evolution in man studied in patients with first-time coronary occlusion in comparison to different species - implications for assessment of myocardial salvage

<p>Abstract</p> <p>Background</p> <p>The time course of infarct evolution, i.e. how fast myocardial infarction (MI) develops during coronary artery occlusion, is well known for several species, whereas no direct evidence exists on the evolution of MI size normalized to myocardium at risk (MaR) in man. Despite the lack of direct evidence, current literature often refers to the "golden hour" as the time during which myocardial salvage can be accomplished by reperfusion therapy. Therefore, the aim of the present study was to investigate how duration of myocardial ischemia affects infarct evolution in man in relation to previous animal data. Consecutive patients with clinical signs of acute myocardial ischemia were screened and considered for enrollment. Particular care was taken to assure uniformity of the patients enrolled with regard to old MI, success of revascularization, collateral flow, release of biochemical markers prior to intervention etc. Sixteen patients were ultimately included in the study. Myocardium at risk was assessed acutely by acute Myocardial Perfusion Single photon emission computed tomography (MPS) and by T2 imaging (T2-STIR) cardiovascular magnetic resonance (CMR) after one week in 10 of the 16 patients. Infarct size was measured by late gadolinium enhancement (LGE) at one week.</p> <p>Results</p> <p>The time to reach 50% MI of the MaR (T₅₀) was significantly shorter in pigs (37 min), rats (41 min) and dogs (181 min) compared to humans (288 min). There was no significant difference in T₅₀when using MPS compared to T2-STIR (p = 0.53) for assessment of MaR (288 ± 23 min vs 310 ± 22 min, T₅₀± standard error). The transmural extent of MI increased progressively as the duration of ischemia increased (R²= 0.56, p < 0.001).</p> <p>Conclusion</p> <p>This is the first study to provide direct evidence of the time course of acute myocardial infarct evolution in relation to MaR in man with first-time MI. Infarct evolution in man is significantly slower than in pigs, rats and dogs. Furthermore, infarct evolution assessments in man are similar when using MPS acutely and T2-STIR one week later for determination of MaR, which significantly facilitates future clinical trials of cardioprotective therapies in acute coronary syndrome by the use of CMR.</p

An artificial neural network to safely reduce the number of ambulance ECGs transmitted for physician assessment in a system with prehospital detection of ST elevation myocardial infarction

<p>Abstract</p> <p>Background</p> <p>Pre-hospital electrocardiogram (ECG) transmission to an expert for interpretation and triage reduces time to acute percutaneous coronary intervention (PCI) in patients with ST elevation Myocardial Infarction (STEMI). In order to detect all STEMI patients, the ECG should be transmitted in all cases of suspected acute cardiac ischemia. The aim of this study was to examine the ability of an artificial neural network (ANN) to safely reduce the number of ECGs transmitted by identifying patients without STEMI and patients not needing acute PCI.</p> <p>Methods</p> <p>Five hundred and sixty ambulance ECGs transmitted to the coronary care unit (CCU) in routine care were prospectively collected. The ECG interpretation by the ANN was compared with the diagnosis (STEMI or not) and the need for an acute PCI (or not) as determined from the Swedish coronary angiography and angioplasty register. The CCU physician's real time ECG interpretation (STEMI or not) and triage decision (acute PCI or not) were registered for comparison.</p> <p>Results</p> <p>The ANN sensitivity, specificity, positive and negative predictive values for STEMI was 95%, 68%, 18% and 99%, respectively, and for a need of acute PCI it was 97%, 68%, 17% and 100%. The area under the ANN's receiver operating characteristics curve for STEMI detection was 0.93 (95% CI 0.89-0.96) and for predicting the need of acute PCI 0.94 (95% CI 0.90-0.97). If ECGs where the ANN did not identify a STEMI or a need of acute PCI were theoretically to be withheld from transmission, the number of ECGs sent to the CCU could have been reduced by 64% without missing any case with STEMI or a need of immediate PCI.</p> <p>Conclusions</p> <p>Our ANN had an excellent ability to predict STEMI and the need of acute PCI in ambulance ECGs, and has a potential to safely reduce the number of ECG transmitted to the CCU by almost two thirds.</p

Engraftment of engineered ES cell–derived cardiomyocytes but not BM cells restores contractile function to the infarcted myocardium

Cellular cardiomyoplasty is an attractive option for the treatment of severe heart failure. It is, however, still unclear and controversial which is the most promising cell source. Therefore, we investigated and examined the fate and functional impact of bone marrow (BM) cells and embryonic stem cell (ES cell)–derived cardiomyocytes after transplantation into the infarcted mouse heart. This proved particularly challenging for the ES cells, as their enrichment into cardiomyocytes and their long-term engraftment and tumorigenicity are still poorly understood. We generated transgenic ES cells expressing puromycin resistance and enhanced green fluorescent protein cassettes under control of a cardiac-specific promoter. Puromycin selection resulted in a highly purified (>99%) cardiomyocyte population, and the yield of cardiomyocytes increased 6–10-fold because of induction of proliferation on purification. Long-term engraftment (4–5 months) was observed when co-transplanting selected ES cell–derived cardiomyocytes and fibroblasts into the injured heart of syngeneic mice, and no teratoma formation was found (n = 60). Although transplantation of ES cell–derived cardiomyocytes improved heart function, BM cells had no positive effects. Furthermore, no contribution of BM cells to cardiac, endothelial, or smooth muscle neogenesis was detected. Hence, our results demonstrate that ES-based cell therapy is a promising approach for the treatment of impaired myocardial function and provides better results than BM-derived cells

Tumor necrosis factor-a in atherosclerosis

Tumor necrosis factor-a in atherogenesis Stefan Jovinge, Department of Medicine, King Gustaf Vth Research, Karolinska Hospital, Karolinska Institute, Stockholm, Sweden The presence of inflammatory cells is prominent at all phases of the atherosclerotic process leaving no doubt that the inflammation is of central importance in atherosclerosis. The recruitment of inflammatory cells into the vessel wall is therefore a key event in early lesion formation. Hypercholesterolemia, which is one of the most important risk factors for cardiovascular disease, has been shown to lead to an accumulation of lipids in the vessel wall where local oxidative processes modify them. Oxidized LDL particles have cytotoxic as well as pro-inflammatory properties. Tumor necrosis factor (TNF)-a is a cytokine central to the inflammatory reaction. Moreover, TNFa plays an important role in the induction of matrix degrading enzymes necessary for the SMC migration seen in the further development of the atherosclerotic lesion. TNFa has also a well-established role in the role in triglyceride metabolism in the sense that it inhibits the major enzyme involved in degradation of triglycerides, lipoprotein lipase, leading to increased levels of triglycerides in the circulation of animals with high levels of TNFa. In addition TNFa has been found to influence glucose metabolism by inhibiting glucose transport proteins as well as insulin receptor signaling. Moreover, insulin resistance has been shown to be associated an increased expression of TNFa in adipose as well as muscle tissue. The major objectives of this investigation were to study the effect of oxidized LDL on the expression of cytokines and their role in the atherosclerotic process. Oxidized LDL was shown to increase secretion of smooth muscle cell SMC mitogens from monocyte/macrophages. TNFa was established to be the major mitogen released by these cells. The effect of oxidized LDL on monocyte/macrophages was mediated by activation of the transcription factor AP-I. TNFa did induce a transient depolymerization of stress fibers in vascular smooth muscle cells which corresponded to an increased cytokinesis of these cells into cell culture wounds. The expression of the transcription factor ets-l gene was also increased these cells. Oxidized LDL was also shown to induce primary necrotic cell death of vascular SMC. The cytokines TNFa and y-interferon had no obvious impact on cell survival, but in combination with oxidized LDL they induced a significant increase in the frequency of cells undergoing cell death by apoptosis. Following injection of LDL, Sprague-Dawley rats accumulated LDL in the vasculature that became oxidatively modified. LDL oxidized prior to injection accumulated in the liver and not in the vasculature. The accumulation of oxidized LDL in the arteries following LDL injection coincided with induction of TNFa protein expression in the vessel wall. This expression was almost completely abolished in rats injected with LDL pre-incubated with the anti-oxidant probucol. Young post-myocardial infarction patients were found to have higher plasma levels of TNFa than age matched controls. Among hyperlipidemic patients TNFa correlated with VLDL triglycerides and cholesterol while there was an inverse relation to HDL cholesterol. In patients treated with bezafibrate VLDL triglycerides levels were reduced by 35% without any significant change in TNFa levels. Moreover, TNFa levels were found to correlate with fasting glucose and proinsulin levels. In conclusion our results show that oxidized LDL has a pro-inflammatory effect by inducing expression of TNFa. They also show that TNFa stimulates migration of vascular cells and that oxidized LDL in combination with the cytokines TNFa and y-interferon induces apoptosis. Finally, they suggest that TNFa has a role in the disturbances of triglyceride and glucose metabolism frequently observed in young patients with myocardial infarction. Key words: atherosclerosis, oxidized low-density lipoprotein, monocytes, tumor necrosis factor-a, cytokinesis, ets-l, matrix metalloproteinases, apoptosis, glucose metabolism, insulin resistance, myocardial infarction ISBN 91-628-2486-