Atrial septal defect patients have an elevated risk for infective endocarditis.

Background. It has been unclear whether simple atrial septal defect (ASD) is an independent risk factor for infective endocarditis (IE). This study aimed to untangle the risk of endocarditis in a large nationwide cohort. Methods. We acquired data from the Finnish hospital discharge register on all individuals with ASD diagnosis from 1969 to 2019. Patients with complex congenital cardiac abnormalities were ruled out. Five individualized controls from the general population were matched to the ASD patient's birth year, sex, and residence at the index date. All the patients with ICD-8, -9, or -10 diagnosis codes for IE were gathered from the hospital discharge registry. Results. Altogether, 8322 patients with ASD and 39,237 individualized controls were enrolled in the study. Median follow-up was 21.6 years (IQR 11.8-36.9) from the first hospital contact. In total, 24 (16 male) cases of infective endocarditis among ASD patients and 10 (8 male) cases among controls were diagnosed during the follow-up. The incidence of endocarditis was 0.11 per 1000 person-years in the patients with ASD and 0.011 per 1000 person-years in the controls. The adjusted risk ratio for endocarditis was 13.51 (95% CI: 6.20-29.46) in patients with ASD compared to the control cohort. Patients with ASD and endocarditis had higher long-term mortality than individualized control patients (MRR 2.25, 95% CI: 1.23-4.11). Conclusions. The incidence of IE in patients with ASD was higher than in the general population. Mortality associated with IE was higher in patients with ASD compared to controls.

Cardiac sarcoidosis: epidemiology, characteristics, and outcome over 25 years in a nationwide study.

BACKGROUND: This study was designed to assess the epidemiology, characteristics, and outcome of cardiac sarcoidosis (CS) in Finland. METHODS AND RESULTS: We identified in retrospect all adult (>18 years of age) patients diagnosed with histologically confirmed CS in Finland between 1988 and 2012. A total of 110 patients (71 women) 51±9 years of age (mean±SD) were found and followed up for outcome events to the end of 2013. The annual detection rate of CS increased >20-fold during the 25-year period, reaching 0.31 in 1×10(5) adults between 2008 and 2012. The 2012 prevalence of CS was 2.2 in 1×10(5). Nearly two thirds of patients had clinically isolated CS. Altogether, 102 of the 110 patients received immunosuppressive therapy, and 56 received an intracardiac defibrillator. Left ventricular function was impaired (ejection fraction <50%) in 65 patients (59%) at diagnosis and showed no overall change over 12 months of steroid therapy. During follow-up (median, 6.6 years), 10 patients died of a cardiac cause, 11 patients underwent transplantation, and another 11 patients suffered an aborted sudden cardiac death. The Kaplan-Meier estimates for 1-, 5-, and 10-year transplantation-free cardiac survival were 97%, 90%, and 83%, respectively. Heart failure at presentation predicted poor outcome (log-rank P=0.0001) with a 10-year transplantation-free cardiac survival of only 53%. CONCLUSIONS: The detection rate of CS has increased markedly in Finland over the last 25 years. With current therapy, the prognosis of CS appears better than generally considered, but patients presenting with heart failure still have poor long-term outcome.

High number of transplanted stem cells improves myocardial recovery after AMI in a porcine model.

OBJECTIVE: The clinical data considering the bone marrow mononuclear cell (BMMNC) therapy in treatment for acute myocardial infarction (AMI) are controversial and the mechanisms remain unknown. Our objective was to study the cardiac function and changes in cytokine levels after administration of BMMNC in experimental AMI model. DESIGN: Unlabeled or Super-Paramagnetic-Iron-Oxide-labeled BMMNCs or saline was injected into myocardium of 31 pigs after circumflex artery occlusion. Ejection fraction (EF) was measured preoperatively, postoperatively and at 21 days by echocardiography. Cardiac MRI was performed postoperatively and after 21 days in 7 BMMNC animals. Serum cytokine levels were measured at baseline, 24 h and 21 days. Cellular homing was evaluated comparing MRI and histology. RESULTS: From baseline to 21 days EF decreased less in BMMNC group (EF mean control -19 SD 12 vs. BMMNC -4 SD 15 percentage points p = 0.02). Cytokine concentrations showed high variability between the animals. MRI correlated with histology in cell detection and revealed BMMNCs in the infarction area. By MRI, EF improved 11 percentage points. The improvement in EF was associated with the number of transplanted BMMNCs detected in the myocardium. CONCLUSION: BMMNC injection after AMI improved cardiac function. Quantity of transplanted BMMNCs correlated with the improvement in cardiac function after AMI.

Superoxide production during ischemia-reperfusion in the perfused rat heart: a comparison of two methods of measurement.

Reactive oxygen species (ROS) have been implicated in many aspects of tissue/cellular metabolic signaling and pathology, including cardioprotection against ischemia-reperfusion damage. Recent reports of enhanced ROS production under global or simulated ischemia in intact heart or isolated cardiomyocytes, respectively, and its decrease again upon reperfusion are paradoxical. Mechanisms for increasing ROS production with decreasing reactant (oxygen) concentration remain elusive, making it important to critically evaluate the experimental methods used to measure ROS production. In the present paper superoxide production in isolated perfused rat hearts was monitored by lucigenin chemiluminescence or dihydroethidine (DHE) oxidation product fluorescence in parallel with redox state of flavin and cytochrome oxidase. Lucigenin luminescence decreased in ischemia and increased again upon reperfusion, transiently reaching values eightfold the control value coincidently with an overshoot of mitochondrial oxygen concentration. Hypoxic perfusion decreased lucigenin chemiluminescence in spite of coronary flow increase, whereas change in lucigenin concentration in the perfusate had negligible effect. In contrast to lucigenin luminescence, the fluorescence of the DHE oxidation product increased continuously during a 30-min global ischemia and decreased precipitously upon reperfusion, this change is coincident with absorption changes of the oxygen-binding protein myoglobin. The time course of DHE oxidation product fluorescence during ischemia and reperfusion was similar to that of the mitochondrial membrane potential probe safranin as shown in perfused heart previously [Ylitalo KV, Ala-Rämi A, Liimatta EV, Peuhkurinen KJ, Hassinen IE. J Mol Cell Cardiol 2000;32:1223-38]. In solution under high oxygen partial pressure DHE was mainly oxidized to a product, whose fluorescence, absorbance and mass spectra were similar to ethidium, and this product behaved like a mitochondrial membrane potential probe in isolated mitochondria. As a membrane permeable cation it accumulates into the mitochondria when the membrane potential is high (high intramitochondrial concentration quenches fluorescence) and then is released (increased fluorescence) during hypoxia/ischemia. Upon reperfusion it is re-accumulated in the mitochondria as the membrane potential recovers. The non-specific oxidation of DHE makes this dye less suitable for superoxide detection in experiments on isolated perfused hearts that necessitate high oxygen partial pressure in the perfusate. The time course of lucigenin luminescence during ischemia/reperfusion is consistent with decreased ROS production during ischemia/hypoxia, while the oxygen concentration is decreased, followed by an overshoot when the heart tissue is reperfused and the oxygen pressures return to normal or above normal.

The effect of bone marrow microenvironment on the functional properties of the therapeutic bone marrow-derived cells in patients with acute myocardial infarction.

BACKGROUND: Treatment of acute myocardial infarction with stem cell transplantation has achieved beneficial effects in many clinical trials. The bone marrow microenvironment of ST-elevation myocardial infarction (STEMI) patients has never been studied even though myocardial infarction is known to cause an imbalance in the acid-base status of these patients. The aim of this study was to assess if the blood gas levels in the bone marrow of STEMI patients affect the characteristics of the bone marrow cells (BMCs) and, furthermore, do they influence the change in cardiac function after autologous BMC transplantation. The arterial, venous and bone marrow blood gas concentrations were also compared. METHODS: Blood gas analysis of the bone marrow aspirate and peripheral blood was performed for 27 STEMI patients receiving autologous stem cell therapy after percutaneous coronary intervention. Cells from the bone marrow aspirate were further cultured and the bone marrow mesenchymal stem cell (MSC) proliferation rate was determined by MTT assay and the MSC osteogenic differentiation capacity by alkaline phosphatase (ALP) activity assay. All the patients underwent a 2D-echocardiography at baseline and 4 months after STEMI. RESULTS: As expected, the levels of pO(2), pCO(2), base excess and HCO(3) were similar in venous blood and bone marrow. Surprisingly, bone marrow showed significantly lower pH and Na(+) and elevated K(+) levels compared to arterial and venous blood. There was a positive correlation between the bone marrow pCO(2) and HCO(3) levels and MSC osteogenic differentiation capacity. In contrast, bone marrow pCO(2) and HCO(3) levels displayed a negative correlation with the proliferation rate of MSCs. Patients with the HCO(3) level below the median value exhibited a more marked change in LVEF after BMC treatment than patients with HCO(3) level above the median (11.13 ± 8.07% vs. 2.67 ± 11.89%, P = 0.014). CONCLUSIONS: Low bone marrow pCO(2) and HCO(3) levels may represent the optimal environment for BMCs in terms of their efficacy in autologous stem cell therapy in STEMI patients.

Tumor necrosis factor alpha promotes the expression of immunosuppressive proteins and enhances the cell growth in a human bone marrow-derived stem cell culture.

Mesenchymal stem cells (MSCs) are widely used in experimental treatments for various conditions that involve normal tissue regeneration via inflammatory repair. It is known that MSCs can secrete multiple soluble factors and suppress inflammation. Even though the effect of MSCs on inflammation has been extensively studied, the effect of inflammation on MSCs is poorly understood. One of the major cytokines released at the site of inflammation is tumor necrosis factor alpha (TNF-α) which is known to induce MSC invasion and proliferation. Therefore, we wanted to test the effects of TNF-α exposure on MSCs derived from human bone marrow. We found, as expected, that cell proliferation was significantly enhanced during TNF-α exposure. However, according to the cell surface marker analysis, the intensity of several antigens in the minimum criteria panel for MSCs proposed by International Society of Cellular Therapy (ISCT) was decreased dramatically, and in certain cases, the criteria for MSCs were not fulfilled. In addition, TNF-α exposure resulted in a significant but transient increase in human leukocyte antigen and CD54 expression. Additional proteomic analysis by two-dimensional difference gel electrophoresis and mass spectrometry revealed three proteins whose expression levels decreased and 8 proteins whose expression levels increased significantly during TNF-α exposure. The majority of these proteins could be linked to immunosuppressive and signalling pathways. These results strongly support reactive and immunosuppressive activation of MSCs during TNF-α exposure, which might influence MSC differentiation stage and capacity.

Catheter ablation of atrial fibrillation in patients with therapeutic oral anticoagulation treatment.

AIMS: Current guidelines recommend discontinuation of oral anticoagulation treatment (OAT) and switch to heparin 2-5 days before catheter ablation of atrial fibrillation (AF). However, increasing evidence leans against the 'bridge therapy' and support continuation of OAT during the procedure. METHODS AND RESULTS: We evaluated the safety of AF ablation among patients with therapeutic OAT. The study population comprised 193 consecutive patients who underwent 228 AF ablation procedures guided by electroanatomical mapping. Periprocedural international normalized ratio was <2 (1.6 ± 0.3) in 103 cases (Group 1) and ≥2 (2.4 ± 0.4) in 125 cases (Group 2). Heparin (5000 IU bolus followed by continuous infusion through an open-irrigated ablation catheter) was used in both groups. No intracardiac echocardiographic guidance was used and activated clotting time (ACT) was not monitored. The incidence of major (intracranial bleeding, tamponade, bleeding that required surgical intervention, or blood transfusion) and minor bleeding complications and all thrombo-embolic events were registered during the 3-month follow-up. There was no statistical difference in major (P = 1.0) and minor complications (P = 0.74) between the groups. The bleeding complications included one surgically corrected groin haematoma in both groups (0.9%), 25 small haematomas at the puncture site (11 in Group 1 (10.7%) and 14 in Group 2 (11.2%), P = 0.90), and two minor pericardial effusions in Group 1. In Group 2, one patient had ischaemic stroke 16 days after the procedure. CONCLUSION: Transseptal puncture and AF ablation can be performed safely in patients with ongoing OAT without intracardiac echocardiographic guidance and ACT monitoring.

Electrocardiographic abnormalities and ventricular tachyarrhythmias after myocardial infarction.

AIMS: To assess the association of electrocardiographic repolarization and depolarization patterns to vulnerability to ventricular tachyarrhythmias. METHODS: In the present case-control study, a 12-lead ECG, signal-averaged ECG (SAECG), T-wave and QRS morphology, and T-wave alternans (TWA) were analyzed in post-MI patients with and without documented sustained ventricular tachycardia (VT) or fibrillation (VF) (VT/VF group, n=40, Non-VT/VF group, n=37, respectively) and healthy subjects (n=41). RESULTS: The QRS complex duration, measured from standard ECG (128 +/- 32 ms vs. 102 +/- 21 ms, p<0.001) or SAECG (125 +/- 25 ms vs. 99 +/- 20 ms, p<0.001), was significantly longer in the VT/VF than Non-VT/VF group. Several T-wave morphology variables, e.g., the total cosine of the angle between the main vectors of T-wave and QRS loops (TCRT), were different in the VT/VF (-0.13 +/- 0.58) and Non-VT/VF group (-0.11 +/- 0.48) compared to the healthy controls (0.47 +/- 0.50, p<0.001). However, there were no significant differences in any of the T-wave morphology variables including TWA between the two post-MI groups. CONCLUSION: Abnormalities in ventricular depolarization are more common among post-MI patients with prior VT/VF than in those without documented ventricular tachyarrhythmias. Abnormal T-wave morphology and TWA seem to reflect the heart disease rather than specifically vulnerability to VT/VF.

Acute homing of bone marrow-derived mononuclear cells in intramyocardial vs. intracoronary transplantation.

OBJECTIVES: Cell homing optimisation after transplantation is critical in myocardial infarction (MI) cell therapy. DESIGN: Eight pigs were randomized to receiving autologous purified (111)indium-labeled bone marrow mononuclear cells (BMMCs) (10(8) cells/2 ml) by intramyocardial (IM) (n=4) or by intracoronary (IC) (n=4) transplantation after 90 minutes occlusion of the CX-coronary artery. Dual isotope SPECT imaging was performed 2 and 24 hours postoperatively. Two animals were additionally analyzed on the sixth postoperative day. Tissue samples from the major organs were analyzed. RESULTS: In SPECT imaging revealed that BMMCs administered using IM injection remained in the injured area. In contrast, minor proportion of IC transplanted cells remained in the myocardium, as most of the cells showed homing in the lungs. Analysis of the biopsies showed a seven-fold greater number of cells in the myocardium for the IM method and a 10-fold greater number of cells in the lungs in the IC group (p < 0.001). CONCLUSIONS: In producing persistently high cell homing at the infarction site, the IM transplantation is superior to the IC transplantation. However, the IC administration might be more specific in targeting injured capillaries and epithelial cells within the infarcted myocardium.

Effects of intracoronary injection of mononuclear bone marrow cells on left ventricular function, arrhythmia risk profile, and restenosis after thrombolytic therapy of acute myocardial infarction.

AIMS: To assess the efficacy and safety of bone marrow cell (BMC) therapy after thrombolytic therapy of an acute ST-elevation myocardial infarction (STEMI). METHODS AND RESULTS: Patients with STEMI treated with thrombolysis followed by percutaneous coronary intervention (PCI) 2-6 days after STEMI were randomly assigned to receive intracoronary BMCs (n = 40) or placebo medium (n = 40), collected and prepared 3-6 h prior PCI and injected into the infarct artery immediately after stenting. Efficacy was assessed by the measurement of global left ventricular ejection fraction (LVEF) by left ventricular angiography and 2-D echocardiography, and safety by measuring arrhythmia risk variables and restenosis of the stented vessel by intravascular ultrasound. At 6 months, BMC group had a greater absolute increase of global LVEF than placebo group, measured either by angiography (mean +/- SD increase 7.1 +/- 12.3 vs. 1.2 +/- 11.5%, P = 0.05) or by 2-D echocardiography (mean +/- SD increase 4.0 +/- 11.2 vs. -1.4 +/- 10.2%, P = 0.03). No differences were observed between the groups in the adverse clinical events, arrhythmia risk variables, or the minimal lumen diameter of the stented coronary lesion. CONCLUSION: Intracoronary BMC therapy is associated with an improvement of global LVEF and neutral effects on arrhythmia risk profile and restenosis of the stented coronary lesions in patients after thrombolytic therapy of STEMI.

[Myocardial infarction in a young patient--with underlying vasculitis]. / Nuoren potilaan sydäninfarkti--taustalla vaskuliitti.

Myocardial infarction in a young patient is rare, and its diagnosis and treatment may be delayed. Vasculitis can cause inflammation in the coronary artery and cause a myocardial infarction even in a young person. We describe a sudden myocardial infarction caused by vasculitis in two young adults having chest pain symptoms.

Ventricular tachyarrhythmia as a primary presentation of sarcoidosis.

AIMS: Sarcoidosis is a multisystem, granulomatous disease with occasional cardiac manifestations. The clinical course of patients with ventricular tachyarrhythmias as a primary presentation of sarcoidosis is mostly unknown. METHODS AND RESULTS: We describe nine patients (four males and five females) in whom sarcoidosis manifested as ventricular tachycardia (VT). The age of the patients was 53 +/- 10 years (range 33-68). The disease was diagnosed by endomyocardial biopsy in eight patients and by lymph node biopsy in one patient. The presenting arrhythmia varied from non-sustained VT to incessant VT and ventricular fibrillation. All patients received implantable cardioverter defibrillator (ICD) and anti-arrhythmic medication. High-dose steroid treatment was used in eight cases. During the follow-up (50 +/- 34 months), five patients underwent appropriate ICD therapies and non-sustained VT episodes were detected in four patients. Two patients developed incessant VT, which was treated by catheter ablation. One patient was referred for heart transplantation. CONCLUSION: Our data indicate that sarcoidosis can manifest as VT without any detectable systemic findings. This makes sarcoidosis an important diagnostic consideration in patients with VT of unknown origin. Arrhythmia control in cardiac sarcoidosis is difficult, and all modern treatments including high-dose steroids, anti-arrhythmic drugs, ICD, and catheter ablation are needed to suppress the arrhythmias.

Utility of plasma apelin and other indices of cardiac dysfunction in the clinical assessment of patients with dilated cardiomyopathy.

Apelin is a recently discovered peptide ligand reported to be involved in the regulation of cardiovascular homeostasis. The exact role of apelin in the pathophysiology of congestive heart failure has remained obscure, and the reported circulating levels of apelin in patients with heart failure have been contradictory. To establish the role of apelin in the assessment of cardiac dysfunction we measured plasma apelin levels in 65 patients with congestive heart failure caused by idiopathic dilated cardiomyopathy (IDC) and 14 healthy volunteers by specific radioimmunoassay. IDC patients were carefully examined including echocardiography, both-sided cardiac catheterization and cardiopulmonary exercise test. In addition, plasma levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), N-terminal pro-atrial natriuretic peptide (NT-proANP), interleukin (IL)-6, tumor necrosis factor alpha (TNF-alpha), epinephrine and norepinephrine were determined. Plasma apelin levels were similar in IDC patients (median 26.5 pg/ml, range<3.40-97.6 pg/ml) and in control subjects (median 24.1 pg/ml, range 19.0-28.7 pg/ml; p=NS). Unlike the levels of NT-proBNP, IL-6, TNF-alpha, and norepinephrine, plasma apelin levels did not reflect the severity of heart failure. Our study demonstrates that although disturbed apelin-APJ signalling in heart may play a role in the pathophysiology of heart failure, circulating apelin levels cannot be applied in the clinical assessment of patients with chronic left ventricular dysfunction.

Two novel mutations in the beta-myosin heavy chain gene associated with dilated cardiomyopathy.

BACKGROUND: Dilated cardiomyopathy (DCM) is familial in approximately 20-35% of cases of idiopathic DCM. Several mutations in the different sarcomere protein genes have been reported to cause DCM. AIMS: We wanted to investigate the role of sarcomere protein gene variants in Finnish DCM patients. METHODS AND RESULTS: We screened all coding exons of five sarcomere protein genes (beta-myosin heavy chain, alpha-tropomyosin, troponin C, troponin I and troponin T) in a well-characterized population of 52 DCM patients in Eastern Finland by the PCR-SSCP and sequencing method. Two novel mutations, Arg1053Gln and Arg1500Trp, in the beta-myosin heavy chain gene in two index patients were detected. The proband with the Arg1053Gln mutation had a dilated left ventricle and impaired systolic function, but other family members carrying this mutation presented with septal hypertrophy. It thus seems that the Arg1053Gln mutation is primarily a HCM mutation, which can also lead to DCM. The other mutation, Arg1500Trp, was associated with a typical DCM phenotype. The Arg1500Trp mutation carrier had only one family member alive, but she did not carry the mutation and, therefore, cosegregation of the mutation and the disease in this family could not be reliably verified. No disease-causing mutations were found in the other sarcomere protein genes. CONCLUSIONS: Two novel mutations in the beta-myosin heavy chain gene were detected in patients with DCM. Overall, mutations in the beta-myosin heavy chain gene seem to be relatively uncommon in Finnish DCM patients.

Ischemic preconditioning does not improve myocardial preservation during off-pump multivessel coronary operation.

BACKGROUND: The value of ischemic preconditioning during coronary operations has remained controversial. The aim of this study was to evaluate the effects of ischemic preconditioning on myocardial energy metabolism and tissue injury during off-pump multivessel coronary surgery. METHODS: Eleven patients with preceding preconditioning were compared with 11 patients without it. The preconditioning group underwent a 5-minute period of ischemia followed by a 5-minute reperfusion period before coronary occlusion for each of the first two anastomoses. RESULTS: The transmyocardial differences (coronary sinus - arterial) in inosine and the sum of adenine degradation products increased in both groups, but the differences in xanthine and hypoxanthine increased only in the preconditioning group. Myocardial lactate production increased to a maximum of 0.09 mmol/L with preconditioning and to a maximum of 0.17 mmol/L without it. Transmyocardial pH differences increased to 0.03 U in both groups. The maximum postoperative concentration of creatine kinase-MB mass was 14.8 microg/L with preconditioning and 6.3 microg/L without preconditioning, and that of troponin I 7.4 microg/L and 5.2 microg/L, respectively. There were no statistically significant differences between the groups, however. CONCLUSIONS: Ischemic preconditioning of 5 minutes followed by reperfusion of 5 minutes during off-pump multivessel coronary artery surgery did not prevent myocardial metabolic derangement and tissue injury and thus cannot be routinely recommended.

Analysis of molecular changes after autologous cell therapy in swine myocardial infarction tissue can reveal novel targets for future therapy.

Although several studies have demonstrated a functional recovery of infarcted myocardial tissue after cell therapy, little is known about the molecular mechanisms behind it. The aim of this study was to characterize the effect of cell therapy at the molecular level to screen for novel target candidates for future therapy of infarcted myocardial tissue. We used a swine acute myocardial infarction model evoked by transient occlusion of the circumflex coronary artery. Autologous bone marrow-derived mononuclear cells (BMMCs) or saline were injected intramyocardially or into the circumflex coronary artery. Samples for protein and RNA analysis were collected from the infarction area and healthy myocardium after a 3 week recovery period and analysed by two-dimensional gel electrophoresis (2DE) and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Proteomic screening detected 13 protein spots which were altered after infarction but had been restored by BMMC treatment. The identification of seven proteins by mass spectrometry revealed that five proteins with decreased expression after infarction corresponded to mitochondrial proteins involved in energy metabolism. Their restored levels after BMMC treatment indicate their involvement in the recovery of heart function. In contrast, the elevated levels of α-crystallin B chain and cathepsin D after infarction suggest an involvement in the pathological mechanisms causing a decreased heart function. This study reveals that cell therapy with BMMCs after myocardial infarction causes restoration of several altered protein levels after 3 weeks and identifies potential marker proteins involved in the pathology of infarction.

Activity of mesenchymal stem cells in a nonperfused cardiac explant model.

Stem cell therapy represents a potential novel additional therapy for acute myocardial infarction. Cardiac applications of stem cell therapy are now undergoing clinical trials though many properties, including localization, possible adhesion, and infiltration of the injected stem cells in the myocardium, have not been studied in detail even in vitro. To study these mechanisms in a controlled microenvironment, we developed a model where mesenchymal stem cells (MSCs) were transported into live, cultured cardiac explants for further co-culture. About 10×10(3) porcine MSCs were injected into freshly excised and isolated cardiac explants of the pig. The explants were present in the culture medium for up to 7 days, with the time course of viability of the myocardial tissue, and the migration and the localization of the injected MSCs were analyzed with histological and immunohistological stainings. The myocyte structure was observed to be well preserved, and proliferation of capillaries and myofibroblasts was detected at the explant periphery. There were injected MSCs localized in the capillaries and in contact with the endothelial cells. The migration range and the number of adherent MSCs increased over time, suggesting active movement of MSCs in the explant. Our results suggest that this cardiac explant culture model is a feasible method for studying the effects of stem cells in the myocardium in vitro.

Granulation tissue is altered after intramyocardial and intracoronary bone marrow-derived cell transfer for experimental acute myocardial infarction.

BACKGROUND: Bone marrow-derived mononuclear cell (BMMC) treatment in acute myocardial infarction (AMI) has been shown to have a beneficial effect. Our objective was to study in detail the histopathological process after the cell therapy after intramyocardial (IM) or intracoronary (IC) administration of BMMCs following experimental AMI. METHODS: Twenty-fours pigs were randomized to the IM group (n=8), the IC group (n=8), and the control group (n=8).After 90 min of transient occlusion of the circumflex coronary artery, BMMCs were injected either intramyocardially or by a transfemoral catheter into the circumflex coronary artery. Echocardiography was performed preoperatively, postoperatively, and after a 21-day recovery period. The heart biopsies were examined histopathologically. Volumetric ex vivo CT scan was performed to evaluate calcification of the infarcted myocardium. RESULTS: The ejection fraction (EF) showed significant recovery in the IM group compared to the control group at Day 21 (P=.05). Despite beneficial histological changes in the infarction site in the IC group, compared to the control group, EF failed to recover. Reduction of collagen density that depicts scar formation was seen in both cell therapy groups compared to the control (P<.001). The number of mitotic cells was higher in the control group compared to the cell therapy groups (P<.001). The IC and IM groups differed significantly from each other in muscle-specific actin staining (P<.001) and smooth muscle actin staining (P<.004). The IM therapy group showed higher density for both stainings. Additionally, macrophage density was higher in the IC group compared to the IM and control groups (P<.002). Both cell therapy regimens substantially diminished tissue calcification; due to the large variation, the effect was not statistically significant. CONCLUSION: BMMC therapy launches cellular changes that affect mostly the repair process in the granulation tissue. The cell transplantation method might have some effect on the magnitude of the effect.