Functional and transcriptomic recovery of infarcted mouse myocardium treated with bone marrow mononuclear cells.

Although bone marrow-derived mononuclear cells (BMNC) have been extensively used in cell therapy for cardiac diseases, little mechanistic information is available to support reports of their efficacy. To address this shortcoming, we compared structural and functional recovery and associated global gene expression profiles in post-ischaemic myocardium treated with BMNC transplantation. BMNC suspensions were injected into cardiac scar tissue 10 days after experimental myocardial infarction. Six weeks later, mice undergoing BMNC therapy were found to have normalized antibody repertoire and improved cardiac performance measured by ECG, treadmill exercise time and echocardiography. After functional testing, gene expression profiles in cardiac tissue were evaluated using high-density oligonucleotide arrays. Expression of more than 18% of the 11981 quantified unigenes was significantly altered in the infarcted hearts. BMNC therapy restored expression of 2099 (96.2%) of the genes that were altered by infarction but led to altered expression of 286 other genes, considered to be a side effect of the treatment. Transcriptional therapeutic efficacy, a metric calculated using a formula that incorporates both recovery and side effect of treatment, was 73%. In conclusion, our results confirm a beneficial role for bone marrow-derived cell therapy and provide new information on molecular mechanisms operating after BMNC transplantation on post ischemic heart failure in mice.

Autoantibodies enhance agonist action and binding to cardiac muscarinic receptors in chronic Chagas' disease.

Chronic Chagasic patient immunoglobulins (CChP-IgGs) recognize an acidic amino acid cluster at the second extracellular loop (el2) of cardiac M(2)-muscarinic acetylcholine receptors (M(2)AChRs). These residues correspond to a common binding site for various allosteric agents. We characterized the nature of the M(2)AChR/CChP-IgG interaction in functional and radioligand binding experiments applying the same mainstream strategies previously used for the characterization of other allosteric agents. Dose-response curves of acetylcholine effect on heart rate were constructed with data from isolated heart experiments in the presence of CChP or normal blood donor (NBD) sera. In these experiments, CChP sera but not NBD sera increased the efficacy of agonist action by augmenting the onset of bradyarrhythmias and inducing a Hill slope of 2.5. This effect was blocked by gallamine, an M(2)AChR allosteric antagonist. Correspondingly, CChP-IgGs increased acetylcholine affinity twofold and showed negative cooperativity for [(3)H]-N-methyl scopolamine ([(3)H]-NMS) in allosterism binding assays. A peptide corresponding to the M(2)AChR-el2 blocked this effect. Furthermore, dissociation assays showed that the effect of gallamine on the [(3)H]-NMS off-rate was reverted by CChP-IgGs. Finally, concentration-effect curves for the allosteric delay of W84 on [(3)H]-NMS dissociation right shifted from an IC(50) of 33 nmol/L to 78 nmol/L, 992 nmol/L, and 1670 nmol/L in the presence of 6.7 x 10(- 8), 1.33 x 10(- 7), and 2.0 x 10(- 7) mol/L of anti-el2 affinity-purified CChP-IgGs. Taken together, these findings confirmed a competitive interplay of these ligands at the common allosteric site and revealed the novel allosteric nature of the interaction of CChP-IgGs at the M(2)AChRs as a positive cooperativity effect on acetylcholine action.

Human antibodies with muscarinic activity modulate ventricular repolarization: basis for electrical disturbance.

INTRODUCTION: In chronic chagasic patients sudden death has been reported when QT interval dispersion is increased and antibodies with muscarinic-like activity have been demonstrated to trigger arrhythmias. The aims were to investigate, in vivo and in vitro, relation between these antibodies and heterogeneity of ventricular repolarization and to identify predictors of cardiac death in chronic chagasic patients. METHODS AND RESULTS: Clinical, electrocardiograph and echocardiograph variables from 32 chronic chagasic patients with moderate to severe left ventricular dysfunction, followed-up for 10 years were analyzed. Sera from chronic chagasic patients with or without muscarinic activity were tested in isolated rabbit hearts to study ventricular repolarization. Stepwise multivariate logistic analysis was applied to identify independent predictors of cardiac death. QT interval dispersion of patients with muscarinic activity (75.9+/-5.5 ms) was larger than that of patients without muscarinic activity (51.3+/-4.0 ms, p<0.001). Maximum uncorrected and corrected QT intervals were not significantly different between groups of patients. Sera from patients with muscarinic activity significantly and reversibly increased QT interval in isolated rabbit hearts (p=0.002). This effect was abolished in the presence of the muscarinic antagonist atropine. Multivariate analysis identified maximum corrected QT intervals and left ventricular end diastolic index as independent predictors of cardiac death (p=0.03 and p=0.02, respectively). CONCLUSIONS: Sera with muscarinic activity from chagasic patients have a strong contribution to evoke ventricular repolarization rhythm disorder. In these patients, ventricular repolarization heterogeneity is increased significantly. In vitro, muscarinic sera reversibly increased repolarization duration. Maximum corrected QT intervals and left ventricular end diastolic index are independent predictors of cardiac death.

[Cell therapy in dilated cardiomyopathy]. / Terapia celular na cardiomiopatia dilatada.

A forty-one-year-old male with systolic heart failure, FC-III NYHA, clinical stage C due to dilated cardiomyopathy was submitted to an autologous transplant of the mononuclear fraction of bone marrow via coronary artery system through heart catheterism. Two months after the procedure, there was a decrease in plasma BNP and cardiac area reduction at the thorax X-ray and nuclear magnetic resonance. The echocardiogram showed decrease of the secondary regurgitation and mitral ring dilatation. There was a better performance at the ergospirometry, with increase of the maximum oxygen consumption and consequent reduction in drug therapy. The absence of adverse events characterized by clinical/hemodynamic instability, enzymatic alteration or electrocardiogram demonstrate the safety and feasibility of this procedure carried out and described with pioneering spirit in dilated cardiomyopathy.

Terapia celular na cardiomiopatia dilatada / Cell therapy in dilated cardiomyopathy

Homem de 41 anos em insuficiência cardíaca sistólica, CF III NYHA, estágio clínico C, por cardiomiopatia dilatada, foi submetido ao transplante autólogo da fração mononuclear da medula óssea, via sistema arterial coronariano, através de cateterismo cardíaco. Dois meses após o procedimento, houve diminuição do BNP plasmático, diminuição da área cardíaca ao estudo radiológico do tórax e à ressonância nuclear magnética. O ecocardiograma demonstrou diminuição do fluxo regurgitante secundário a dilatação do anel mitral. Na ergoespirometria houve melhor desempenho, com aumento do consumo máximo de oxigênio, sendo possível redução da terapêutica medicamentosa. A ausência de eventos adversos caracterizados por: instabilidade clínica/hemodinâmica, alteração enzimática ou eletrocardiográfica apontam para segurança e exeqüibilidade deste procedimento realizado e descrito com pioneirismo na cardiomiopatia dilatada.