Intramyocardial injection of autologous cardiospheres or cardiosphere-derived cells preserves function and minimizes adverse ventricular remodeling in pigs with heart failure post-myocardial infarction.

OBJECTIVES: The purpose of this study was to test the safety and efficacy of direct injection of cardiosphere-derived cells (CDCs) and their 3-dimensional precursors, cardiospheres, for cellular cardiomyoplasty in a mini-pig model of heart failure after myocardial infarction. BACKGROUND: Intracoronary administration of CDCs has been demonstrated to reduce infarct size and improve hemodynamic indexes in the mini-pig model, but intramyocardial injection of CDCs or cardiospheres has not been assessed in large animals. METHODS: Autologous cardiospheres or CDCs grown from endomyocardial biopsies were injected through thoracotomy 4 weeks after anteroseptal myocardial infarction. Engraftment optimization with luciferase-labeled CDCs guided the choice of cell dose (0.5 million cells/site) and target tissue (20 peri-infarct sites). Pigs were randomly allocated to placebo (n = 11), cardiospheres (n = 8), or CDCs (n = 10). Functional data were acquired before injection and again 8 weeks later, after which organs were harvested for histopathology. RESULTS: Beyond the immediate perioperative period, all animals survived to protocol completion. Ejection fraction was equivalent at baseline, but at 8 weeks was higher than placebo in both of the cell-treated groups (placebo vs. CDC, p = 0.01; placebo vs. cardiospheres, p = 0.01). Echocardiographic and hemodynamic indexes of efficacy improved disproportionately with cardiospheres; likewise, adverse remodeling was more attenuated with cardiospheres than with CDCs. Provocative electrophysiologic testing showed no differences among groups, and no tumors were found. CONCLUSIONS: Dosage-optimized direct injection of cardiospheres or CDCs is safe and effective in preserving ventricular function in porcine ischemic cardiomyopathy. Although CDCs and cardiospheres have equivalent effects on left ventricular ejection fraction, cardiospheres are superior in improving hemodynamics and regional function, and in attenuating ventricular remodeling.

Cardiospheres recapitulate a niche-like microenvironment rich in stemness and cell-matrix interactions, rationalizing their enhanced functional potency for myocardial repair.

Cardiac stem cells (CSCs) are promising candidates for use in myocardial regenerative therapy. We test the hypothesis that growing cardiac-derived cells as three-dimensional cardiospheres may recapitulate a stem cell niche-like microenvironment, favoring cell survival and enhancing functional benefit after transplantation into the injured heart. CSCs and supporting cells from human endomyocardial biopsies were grown as cardiospheres and compared with cells cultured under traditional monolayer condition or dissociated from cardiospheres. Cardiospheres self-assembled into stem cell niche-like structures in vitro in suspension culture, while exhibiting greater proportions of c-kit(+) cells and upregulated expression of SOX2 and Nanog. Pathway-focused polymerase chain reaction (PCR) array, quantitative real-time PCR, and immunostaining revealed enhanced expression of stem cell-relevant factors and adhesion/extracellular-matrix molecules (ECM) in cardiospheres including IGF-1, histone deacetylase 2 (HDAC2), Tert, integrin-α(2), laminin-ß(1), and matrix metalloproteinases (MMPs). Implantation of cardiospheres in severe combined immunodeficiency (SCID) mouse hearts with acute infarction disproportionately improved cell engraftment and myocardial function, relative to monolayer-cultured cells. Dissociation of cardiospheres into single cells decreased the expression of ECM and adhesion molecules and undermined resistance to oxidative stress, negating the improved cell engraftment and functional benefit in vivo. Growth of cardiac-derived cells as cardiospheres mimics stem cell niche properties with enhanced "stemness" and expression of ECM and adhesion molecules. These changes underlie an increase in cell survival and more potent augmentation of global function following implantation into the infarcted heart.

Dedifferentiation and proliferation of mammalian cardiomyocytes.

BACKGROUND: It has long been thought that mammalian cardiomyocytes are terminally-differentiated and unable to proliferate. However, myocytes in more primitive animals such as zebrafish are able to dedifferentiate and proliferate to regenerate amputated cardiac muscle. METHODOLOGY/PRINCIPAL FINDINGS: Here we test the hypothesis that mature mammalian cardiomyocytes retain substantial cellular plasticity, including the ability to dedifferentiate, proliferate, and acquire progenitor cell phenotypes. Two complementary methods were used: 1) cardiomyocyte purification from rat hearts, and 2) genetic fate mapping in cardiac explants from bi-transgenic mice. Cardiomyocytes isolated from rodent hearts were purified by multiple centrifugation and Percoll gradient separation steps, and the purity verified by immunostaining and RT-PCR. Within days in culture, purified cardiomyocytes lost their characteristic electrophysiological properties and striations, flattened and began to divide, as confirmed by proliferation markers and BrdU incorporation. Many dedifferentiated cardiomyocytes went on to express the stem cell antigen c-kit, and the early cardiac transcription factors GATA4 and Nkx2.5. Underlying these changes, inhibitory cell cycle molecules were suppressed in myocyte-derived cells (MDCs), while microRNAs known to orchestrate proliferation and pluripotency increased dramatically. Some, but not all, MDCs self-organized into spheres and re-differentiated into myocytes and endothelial cells in vitro. Cell fate tracking of cardiomyocytes from 4-OH-Tamoxifen-treated double-transgenic MerCreMer/ZEG mouse hearts revealed that green fluorescent protein (GFP) continues to be expressed in dedifferentiated cardiomyocytes, two-thirds of which were also c-kit(+). CONCLUSIONS/SIGNIFICANCE: Contradicting the prevailing view that they are terminally-differentiated, postnatal mammalian cardiomyocytes are instead capable of substantial plasticity. Dedifferentiation of myocytes facilitates proliferation and confers a degree of stemness, including the expression of c-kit and the capacity for multipotency.

Engraftment, differentiation, and functional benefits of autologous cardiosphere-derived cells in porcine ischemic cardiomyopathy.

BACKGROUND: Cardiosphere-derived cells (CDCs) isolated from human endomyocardial biopsies reduce infarct size and improve cardiac function in mice. Safety and efficacy testing in large animals is necessary for clinical translation. METHODS AND RESULTS: Mesenchymal stem cells, which resemble CDCs in size and thrombogenicity, have been associated with infarction after intracoronary infusion. To maximize CDC engraftment while avoiding infarction, we optimized the infusion protocol in 19 healthy pigs. A modified cocktail of CDCs in calcium-free PBS, 100 U/mL of heparin, and 250 microg/mL of nitroglycerin eliminated infusion-related infarction. Subsequent infusion experiments in 17 pigs with postinfarct left ventricular dysfunction showed CDC doses > or =10(7) but <2.5 x 10(7) result in new myocardial tissue formation without infarction. In a pivotal randomized study, 7 infarcted pigs received 300,000 CDCs/kg (approximately 10(7) total) and 7 received placebo (vehicle alone). Cardiac magnetic resonance imaging 8 weeks later showed CDC treatment decreased relative infarct size (19.2% to 14.2% of left ventricle infarcted, P=0.01), whereas placebo did not (17.7% to 15.3%, P=0.22). End-diastolic volume increased in placebo, but not in CDC-treated animals. Hemodynamically, the rate of pressure change (dP/dt) maximum and dP/dt minimum were significantly better with CDC infusion. There was no difference between groups in the ability to induce ventricular tachycardia, nor was there any tumor or ectopic tissue formation. CONCLUSIONS: Intracoronary delivery of CDCs in a preclinical model of postinfarct left ventricular dysfunction results in formation of new cardiac tissue, reduces relative infarct size, attenuates adverse remodeling, and improves hemodynamics. The evidence of efficacy without obvious safety concerns at 8 weeks of follow-up motivates human studies in patients after myocardial infarction and in chronic ischemic cardiomyopathy.

Effects of atorvastatin on ventricular late potentials and repolarization dispersion in patients with hypercholesterolemia.

Emerging evidence suggests that statins have a favorable impact on the reduction of arrhythmia events and sudden cardiac death in patients with structural heart disease. We aimed to investigate the possibly and directly favorable effects of statins on ventricular late potentials, QT dispersion, and transmural dispersion of repolarization attained by analyzing clinical electrocardiography (ECG) risk stratification parameters in patients with hypercholesterolemia without structural heart disease. In total, 82 patients (45 females; mean age, 62 +/- 10 years) with hypercholesterolemia were enrolled in this prospective study to examine the effects of statin therapy (atorvastatin 10 mg/day for 3 months) on ECG risk stratification parameters. Surface 12-lead ECG and signal-average ECG (SAECG) were recorded before and after statin treatment. The SAECG parameters, QT dispersion, Bazett-corrected QT (QTc) dispersion, T wave peak-to-end interval (Tpe), and percentage of Tpe/QT interval were calculated and compared before and after statin therapy. Twelve-lead ambulatory 24-hour ECGs were recorded in 12 patients. The results demonstrated that after statin therapy for 3 months, serum levels of total cholesterol and low-density lipoprotein cholesterol were significantly reduced (both p values < 0.001). However, neither significant changes of each SAECG parameter nor the frequency of late potentials were demonstrated after atorvastatin therapy. In addition, no significant changes in QT dispersion, QTc dispersion, Tpe, or Tpe/QT were found. However, 24-hour ambulatory ECG revealed a flattening effect of circadian variation of QTc dispersion after atorvastatin therapy. In conclusion, the favorable antiarrhythmia effect of atorvastatin (10 mg/day) therapy cannot be directly reflected by analyzing these noninvasive ECG risk stratification parameters in low-risk patients with hypercholesterolemia.

Ruptured sinus of valsalva and complete atrioventricular block complicating fulminant course of infective endocarditis: a case report and literature review.

Patients with infective endocarditis usually developed persistent fever and heart failure, especially when the valve structures are invaded and destroyed. Persistent bacteremia often leads to severe sepsis or overwhelming septic shock. Septic emboli from the vegetation will possibly result in systemic thromboembolism with multiple organ infarction. Patients with infective endocarditis have been reported to present with either ruptured sinus of Valsalva or complete atrioventricular block. However, both of these serious complications occurring in a single patient is rare. In this case report, we present a 54-year-old man with a previous history of alcoholic cirrhosis and chronic renal failure who suffered from a fulminant course of infective endocarditis. Simultaneously, ruptured sinus of Valsalva and complete atrioventricular block further complicated the preexisting septic shock and multiple organ failure.

Evaluating the prevalence of silent coronary artery disease in asymptomatic patients with spinal cord injury.

To evaluate the prevalence of coronary artery disease (CAD) in patients with spinal cord injury (SCI), 47 clinically asymptomatic SCI patients received thallium-201 myocardial perfusion single photon emission computed tomography (Tl-201 SPECT) after dipyridamole administration for the diagnosis of CAD. There were 4 groups as follows; group 1: 13 patients with quadriplegia and complete SCI, group 2: 11 patients with quadriplegia and incomplete SCI, group 3: 11 patients with paraplegia and complete SCI, and group 4: 12 patients with paraplegia and incomplete SCI. There were no significant differences in sex distribution, ages, SCI duration, or CAD risk factors among the SCI patients in the 4 groups. All Tl-201 SPECT images were interpreted by the agreement of 2 experienced nuclear medicine physicians without prior knowledge of the patients' histories. A total of 30 of 47 (63.8%) SCI patients had abnormal Tl-201 SPECT findings. Among the 4 groups of SCI patients, those in groups 1 and 4 had the significantly highest and lowest prevalences of abnormal Tl-201 SPECT findings, respectively. We concluded that combined quadriplegia and complete SCI is an important CAD risk factor in SCI patients based on the objective evidence of intravenous dipyridamole cardiac stress testing with Tl-201 SPECT.

Tolerability of ramipril 10 mg daily in high-risk cardiovascular patients in Taiwan: experience from Kaohsiung Medical University Chung-Ho Memorial Hospital.

The Heart Outcomes Prevention Evaluation (HOPE) study demonstrated that the angiotensin-converting enzyme inhibitor, ramipril, significantly reduces mortality, myocardial infarction and stroke in high-risk cardiovascular patients, beyond the benefits from blood pressure lowering. The tolerability of ramipril 10 mg/day has been an important concern when applying these results. Following the same criteria as the HOPE study, we investigated the adverse effects profile and tolerability of 10 mg ramipril in high-risk patients at our institution. In total, 92 patients with high cardiovascular risk were eligible for this study. Initially, ramipril was prescribed 2.5 mg orally once daily, and then titrated up to 5.0, 7.5, and 10.0 mg/day at 1-month intervals. The target maintenance dose was 10 mg/day. All adverse events were recorded during at least 3 months of follow-up. After 4-6 months of the titration protocol, only 18 patients (25.3%) reached and remained on ramipril 10 mg/day; 11 (15.5%), 22 (30.9%), and 20 patients (28.2%) remained on 2.5, 5.0, and 7.5 mg/day, respectively. Twenty-one patients (22.6%) had at least one adverse event. Twelve patients (13.0%) stopped treatment because of adverse effects. A total of 23 episodes of adverse events were reported, including cough (15.1%), dizziness (6.0%), and hypotension (2.4%). Ramipril was relatively well tolerated in our study population. However, only one-quarter of our patients reached the target maintenance dose of 10 mg/day. Dry cough, dizziness, and hypotension were the major side effects. About 15% of our patients discontinued ramipril treatment, which is comparable with previous reports.

Ruptured aneurysm of the sinus of valsalva into the right atrium without ventricular septal defect: a case report and literature review.

Aneurysm of the sinus of Valsalva (ASV), frequently associated with ventricular septal defect (VSD), is a rare cardiac disease that may be acquired or congenital. Rupture of an ASV, rare in the noncoronary cusp, usually produces serious hemodynamic change and carries poor prognosis if not treated surgically. We present the case of a 55-year-old female who came to us complaining of exertional dyspnea. Transthoracic echocardiography and aortography showed a noncoronary cusp ASV with rupture into the right atrium but without VSD. Because of high left to right shunt flow, she underwent successful surgical intervention with aneurysm repair approached from both the aorta and right atrium with a knitted Dacron patch. This was a rare case of noncoronary cusp involvement in ASV that ruptured into the right atrium without VSD.

Successful retrieval of dislodged paclitaxel-eluting stent with a nitinol loop snare: a case report.

Coronary stent dislodgment or embolization before deployment is a rare but challenging complication in interventional cardiology. Intracoronary embolization of the dislodged stent is associated with a high risk of coronary occlusion, due to thrombus formation and subsequent myocardial infarction. Furthermore, systemic embolization may cause severe cerebrovascular events. Nonsurgical retrieval strategies for this complication have been suggested, but bailout cardiac surgery may be indicated if percutaneous retrieval attempts fail. To our knowledge, this is the first case report of intracoronary drug-eluting stent dislodgment, and successful retrieval was accomplished by a loop snare technique. With the increasing trend of using drug-eluting stents in percutaneous coronary intervention, the likelihood of stent dislodgment or embolization may increase. It should be kept in mind, especially by coronary interventionists, how to manage this complication.