Cardiosphere-derived cells do not improve cardiac function in rats with cardiac failure.

BACKGROUND: Heart failure represents an important public health issue due to its high costs and growing incidence worldwide. Evidence showing the regenerative potential of postmitotic heart tissue has suggested the existence of endogenous cardiac stem cells in adult hearts. Cardiosphere-derived cells (CDC) constitute a candidate pool of such cardiac stem cells. Previous studies using acute myocardial infarction (MI) models in rodents demonstrated an improvement in cardiac function after cell therapy with CDC. We evaluated the therapeutic potential of CDC 60 days after MI in a rat model. METHODS: CDC were obtained from human discarded myocardial tissue and rat hearts by enzymatic digestion with collagenase II. At 10-15 days after isolation, small, round, phase-bright cells (PBCs) appeared on top of the adherent fibroblast-like cells. The PBCs were collected and placed on a nonadherent plate for 2 days, where they formed cardiospheres which were then transferred to adherent plates, giving rise to CDC. These CDC were characterized by flow cytometry. Wistar rats were submitted to MI through permanent occlusion of the anterior descending coronary artery. After 60 days, they were immunosuppressed with cyclosporine A during 10 days. On the third day, infarcted animals were treated with 5 × 105 human CDC (hCDC) or placebo through intramyocardial injection guided by echocardiogram. Another group of animals was treated with rat CDC (rCDC) without immunosuppression. hCDC and rCDC were stably transduced with a viral construct expressing luciferase under control of a constitutive promoter. CDC were then used in a bioluminescence assay. Functional parameters were evaluated by echocardiogram 90 and 120 days after MI and by Langendorff at 120 days. RESULTS: CDC had a predominantly mesenchymal phenotype. Cell tracking by bioluminescence demonstrated over 85% decrease in signal at 5-7 days after cell therapy. Cardiac function evaluation by echocardiography showed no differences in ejection fraction, end-diastolic volume, or end-systolic volume between groups receiving human cells, rat cells, or placebo. Hemodynamic analyses and infarct area quantification confirmed that there was no improvement in cardiac remodeling after cell therapy with CDC. CONCLUSION: Our study challenges the effectiveness of CDC in post-ischemic heart failure.

The relation between neutrophil-to-lymphocyte ratio and coronary chronic total occlusions.

BACKGROUND: Neutrophil-to-lymphocyte ratio (NLR) is a marker of systemic inflammation that correlates with cardiac events. This study assessed the association between NLR and the presence of chronic coronary total occlusion (CTO). METHODS: The study population included 225 patients, a control group (n = 75), a coronary artery disease group (n = 75), and a CTO group (n = 75). NLR was compared in the three groups. RESULTS: NLR levels were significantly higher in the CTO than in the other two groups (p < 0.001). Bivariate correlation analysis showed a positive correlation between NLR and SYNTAX Score, and multivariate logistic regression analysis found that NLR was an independent predictor of CTO. ROC analysis showed that an NLR cut-off of 2.09 could distinguish between patients with and without CTO (AUC = 0.74; 95% CI, 0.68-0.81), with a specificity of 69.3% and a sensitivity of 61%. CONCLUSION: NLR may be useful as a marker of CTO.

Should we establish a new protocol for the treatment of peripartum myocardial infarction?

Peripartum myocardial infarction is a rare event that is associated with high mortality rates. The differential diagnosis includes coronary artery dissection, coronary artery thrombosis, vascular spasm, and stenosis. Our evaluation of 2 cases over a 5-year time period has led to a hypothesis that peripartum myocardial infarction is an immune-mediated event secondary to coronary endothelial sensitization by fetal antigen. In our patients, we supplemented standard medical therapy with immunotherapy consisting of corticosteroids, plasmapheresis, and intravenous immunoglobulin. Herein, we present our most recent case-that of a 29-year-old black woman (gravida V, para IV), 2 weeks postpartum with no relevant medical history. She presented with a 1-week history of chest pain. Initial electrocardiographic and cardiac biomarkers were consistent with acute coronary syndrome. Echocardiography revealed reduced systolic function with inferior-wall hypokinesis. Angiography revealed diffuse disease with occlusion of the left anterior descending coronary artery not amenable to revascularization. We were successful in treating the myocardial infarction without the use of catheter-based interventions, by modifying the immunologic abnormalities. Two cases do not make a protocol. Yet we believe that this case and our earlier case lend credence to the hypothesis that peripartum myocardial infarction arises from sensitization by fetal antigens. This concept and the immune-modifying treatment protocol that we propose might also assist in understanding and treating other inflammatory-disease states such as peripartum cardiomyopathy and standard acute myocardial infarction. All of this warrants further investigation.

Common haplotype of interleukin-6 gene is associated with chronic total occlusions of coronary arteries.

AIM: Genetic polymorphisms in genes coding for cytokines may predispose patients to coronary artery disease and chronic total occlusion (CTO) of coronary arteries. The aim of the study was to evaluate association of common genetic variations of interleukins (IL) with CTOs. METHODS: We reviewed coronary angiograms and evaluated presence of CTOs in 684 consecutive patients with no history of revascularization. The following genetic variations were analyzed: IL-1B +3954 C>T, IL-1B -511 C>T, IL-1RN VNTR and haplotypes of IL-6 encompassing IL-6 -596 G>A, IL-6 -572 G>C, IL-6 -373 AnTn and IL-6 -174 G>C polymorphisms. RESULTS: In 254 patients (37.1%) CTO of at least one artery was found. We observed nine IL-6 haplotypes, of which five were common (>1%) and one (GG9/12G, n=8) was not previously reported in literature. The most prevalent IL-6 haplotype (AG8/12C or Hap*1, 49.5%) correlated with CTOs, that were present in 31.5%, 36.5% and 44.5% of patients with none, one and two Hap*1, respectively (OR [95%CI] 1.252 [0.844-1.856] and 1.746 [1.104-2.762] for heterozygots and homozygots, respectively). In multivariate analysis this association became non-significant (OR [95%CI] 1.202 [0.805-1.796] and 1.529 [0.955-2.450]). In subgroup analysis Hap*1 was, however, associated with CTOs in the left anterior descending artery (p for trend 0.032) and the left circumflex artery (P=0.047), but not in the right coronary artery (p=0.799). In multivariate analysis CTOs of the left coronary arteries were associated only with total cholesterol (OR [95%CI] 1.170 [1.020-1.341]) and Hap*1 (OR [95%CI] 1.469 [0.914-2.361] and 1.970 [1.151-3.372] for heterozyogots and homozygots, respectively). CONCLUSION: Our study suggests that common IL-6 haplotype (AG8/12C or Hap*1) is associated with development of CTOs in left coronary arteries.

The indirect alloimmune response causes microvascular endothelial dysfunction-a possible role for alloantibody.

BACKGROUND: The causes of endothelial dysfunction after cardiac transplantation are unknown. Here, we have investigated whether the indirect alloimmune response mediates endothelial dysfunction in a major histocompatibility complex class I mismatch model. METHODS: PVG.RT1 rat hearts were transplanted into thymectomized CD8 T-cell-depleted allogeneic (PVG.R8) or syngeneic (PVG.RT1) recipients. Alloantibody was assessed at 2, 4, and 8 weeks. Cardiac allograft vasculopathy, the nature of the inflammatory infiltrate, and origin of endothelial cells were examined at 1, 2, 4, and 8 weeks. Endothelial function was assessed by Langendorff preparations at 1, 2, and 4 weeks. RESULTS: Recipients produced alloantibody and showed luminal occlusion at 1 (17.7%±8.0%), 2 (23.2%±4.9%), 4 (34.3%±5.0%), and 8 weeks (58.1%±1.8%) posttransplantation. The major inflammatory features of the allografts consisted of CD11b monocytes, CD4 T cells, and C4d deposition. At 1 week, the basal coronary flow and the vasodilator response to 5-hydroxytrytamine of syngeneic and allografted hearts were inhibited compared with normal hearts. At 4 weeks, the basal coronary flow of allografts was 54% lower than syngrafts (P<0.01), and 5- hydroxytrytamine and sodium nitroprusside did not evoke an increase in coronary flow in the allograft heart compared with syngeneic controls (P<0.01). Culture of aortic rings with antibody to major histocompatibility complex class I inhibited endothelium-dependent vasodilation to acetylcholine. CONCLUSION: Transient microvascular endothelial dysfunction occurred in syngeneic and allogeneic cardiac grafts after transplantation. Syngeneic but not allogeneic grafts recovered, suggesting the indirect immune response, consisting of CD4 T cells, monocytes, and antibody, mediates endothelial dysfunction. A possible role for alloantibody in endothelial dysfunction is discussed.

Increased levels of procoagulant tissue factor-bearing microparticles within the occluded coronary artery of patients with ST-segment elevation myocardial infarction: role of endothelial damage and leukocyte activation.

OBJECTIVE: During myocardial infarction, platelet activation and endothelial apoptosis are responsible for the release of procoagulant membrane-derived microparticles (MPs) in the bloodstream. Few data are available on the potential role played by MPs in coronary atherothrombosis. In the present study, we investigated the levels and cellular origins of MPs within the occluded coronary artery of patients with ST-segment elevation myocardial infarction (STEMI) treated by primary angioplasty (PCI). METHODS: A total of 12 patients with STEMI treated by primary PCI within 24h of symptom onset were included in this study. MPs procoagulant activity and cellular origin were characterized within the occluded coronary artery before PCI (C(0)), after restoration of the epicardial blood flow (C(1)), and in blood collected from the femoral artery (F). RESULTS: Levels of leukocyte-derived CD11a(+) MPs, endothelial-derived CD105(+) MPs, and tissue factor (TF)-bearing MPs were significantly higher within the occluded coronary artery than in peripheral blood samples. Restoration of the epicardial blood flow led to a significant reduction of procoagulant CD11a(+) and CD105(+) MPs by 30% and 42%, respectively (p<0.05). CONCLUSIONS: Elevation of procoagulant MPs within the occluded coronary artery of patients with STEMI suggests their pathophysiological role in coronary atherothrombosis.

Monitoring of cell therapy and assessment of cardiac function using magnetic resonance imaging in a mouse model of myocardial infarction.

We have developed a mouse severe combined immunodeficient (SCID) model of myocardial infarction based on permanent coronary artery occlusion that allows long-term functional analysis of engrafted human embryonic stem cell-derived cardiomyocytes, genetically marked with green fluorescent protein (GFP), in the mouse heart. We describe methods for delivery of dissociated cardiomyocytes to the left ventricle that minimize scar formation and visualization and validation of the identity of the engrafted cells using the GFP emission spectrum, and histological techniques compatible with GFP epifluorescence, for monitoring phenotypic changes in the grafts in vivo. In addition, we describe how magnetic resonance imaging can be adapted for use in mice to monitor cardiac function non-invasively and repeatedly. The model can be adapted to include multiple control or other cell populations. The procedure for a cohort of six mice can be completed in a maximum of 13 weeks, depending on follow-up, with 30 h of hands-on time.