Ingo Kutschka

Induced pluripotent stem cell (iPSC)-derived Flk-1 progenitor cells engraft, differentiate, and improve heart function in a mouse model of acute myocardial infarction

AIMS Induced pluripotent stem cell (iPSC)-derived cardiovascular progenitor cells represent a suitable autologous cell source for myocardial regeneration as they have the capability to form myocardial cells and to contribute to revascularization. As a first proof of concept we evaluated the potential of a murine iPSC-derived cardiovascular progenitor population, which expresses the surface marker foetal liver kinase-1 (Flk-1), to restore myocardial tissue and improve cardiac function after acute myocardial infarction (MI) in mice. METHODS AND RESULTS iPSC-derived Flk-1(pos) vs. Flk-1(neg) cells were selected by fluorescence activated cell sorting (FACS) and injected into the ischaemic myocardium of left anterior descending coronary artery (LAD)-ligated mice. Addressing safety aspects we used an octamer binding factor 4 (Oct4)-enhanced green fluorescent protein (eGFP) expressing iPSC clone from the transgenic Oct4-eGFP reporter mouse strain OG2 to enable FACS-based depletion of undifferentiated cells prior to transplantation. Infarcted animals were treated with placebo (phosphate-buffered saline, n = 13), Flk-1(neg) cells (n = 14), or Flk-1(pos) cells (n = 11; 5 × 10(5) cells each). Heart function was evaluated by magnetic resonance imaging and conductance catheter analysis 2 weeks postoperatively. Cardiovascular in vitro and in vivo differentiations were investigated by immunofluorescence staining. Treatment with Flk-1(pos) and Flk-1(neg) cells resulted in a favourable myocardial remodelling and improved left ventricular function. Engraftment and functional benefits were superior after transplantation of Flk-1(pos) compared with Flk-1(neg) cells. Furthermore, Flk-1(pos) grafts contained considerably more vascular structures in relation to Flk-1(neg) grafts. CONCLUSION iPSC-derived Flk-1(pos) progenitor cells differentiate into cardiovascular lineages in vitro and in vivo and improve cardiac function after acute MI. This proof of concept study paves the way for an autologous iPSC-based therapy of MI.

Isolated surgical aortic valve replacement after previous coronary artery bypass grafting with patent grafts: is this old-fashioned technique obsolete?

AIM High-risk patients are currently being evaluated for various catheter-based aortic valve replacement (AVR) techniques. To identify an individual patients risk, scores such as the EuroSCORE or STS risk calculator (RC) are used. The aim of the present study was to evaluate the surgical results in patients who underwent isolated AVR via a median re-sternotomy after prior CABG. PATIENTS AND METHODS Between 01/96 and 01/08, 349 patients underwent AVR as a redo procedure. One hundred and thirty patients had undergone previous CABG; in 39 patients (29 male, median age 75 (60-84)) preoperative coronary angiography revealed open grafts with no need for additional revascularization (30 had LIMA grafts). These patients underwent isolated AVR. Operative mortality was calculated using the standard and logistic EuroSCORE, and the STS RC. RESULTS Operative (30-day mortality) was 5% (2 patients). Mean calculated predicted mortality rates for the cohort were: 12+/-3% for the standard, and 32+/-21% for the logistic EuroSCORE, and 10+/-4% according to the STS RC. Receiver operated characteristics (ROC) analysis revealed 100% specificity for standard EuroSCOREs up to 12.5%, logistic EuroSCOREs up to 39.7% and up to 17.45% for STS RC, with a sensitivity of 69.5%, 75% and 97.2%, respectively. The STS RC showed significant better prediction of mortality than the EuroSCOREs (p=0.006). CONCLUSIONS Conventional AVR as a redo procedure after CABG with patent grafts can be performed with excellent results and lower mortality than estimated. Results of newer catheter-based AVR approaches should not to be compared with artificial scores to justify high morbidity rates.

Placement of 2 implantable centrifugal pumps to serve as a total artificial heart after cardiectomy

2. Atik E, Barbero-Marcial M, Tanamati C, Kajita L, Ebaid M, Jatene A. Anomalous origin of the left coronary artery from the right pulmonary artery with intramural aortic trajectory. Clinicosurgical diagnostic implications. Arq Bras Cardiol. 1999; 73:181-90. 3. Turley K, Szarnicki RJ, Flachsbart KD, Richter RC, Popper RW, Tarnoff H. Aortic implantation is possible in all cases of anomalous origin of the left coronary artery from the pulmonary artery. Ann Thorac Surg. 1995;60:84-9. 4. Goldberg SP, Mitchell MB, Campbell DN, Tissot C, Lacour-Gayet F. Anomalous left coronary artery from the pulmonary artery with an intramural course within

Improved right ventricular function after intracoronary administration of a C1 esterase inhibitor in a right heart transplantation model

OBJECTIVE Myocardial injury from ischemia can be augmented after reperfusion due to proinflammatory events including complement activation, leukocyte adhesion, and release of various chemical mediators. It has been shown that intracoronary administration of a C1 esterase inhibitor (C1 INH) significantly reduces myocardial necrosis in an experimental model of ischemia. Our study addresses the question whether the most susceptible region of the heart for ischemic injury, the right ventricle (RV), can benefit from the protective effects of C1 esterase inhibition after transplantation. METHODS To precisely control RV volume in vivo an isovolumic model was used in which the RV volume was regulated using an intracavity high compliance balloon inserted into donor hearts of domestic pigs (34+/-4 kg). After 4 h of ischemia, donor hearts were transplanted into recipient pigs (44+/-4 kg). Treatment groups, each with six animals, consisted of C1 INH treatment or control. After opening the cross clamp, the C1 INH group animals received 20 IU/kg body weight of C1 INH intracoronary over a 5 min period. The control animals received no drug therapy. The hearts were reperfused for 60 min, and thereafter the RV balloon volume was increased in 10 ml increments until RV failure occurred. These measurements were repeated after 120 min of reperfusion. RESULTS There was no significant difference in maximal RV developed pressure between the two groups (after 1 h, 35.7+/-5.9 vs. 40.6+/-12.7 mm Hg; after 2 h, 41.5+/-10.7 vs. 46.3+/-15.2 mm Hg; for C1 INH and control animals, respectively). However, the RV could be loaded with a significantly higher volume after both 1 h (60.0+/-20.0 ml (C1 INH) vs. 46.7+/-13.7 ml (control) balloon volume, P<0.05), and 2 h of reperfusion (70.0+/-8.9 ml vs. 60.0+/-6.3 ml; C1 INH and control animals, respectively; P<0.05). CONCLUSIONS Intracoronary administration of a C1 INH significantly improves right ventricular function in an experimental transplant model. Thus, inhibition of the classic complement cascade may be a promising therapeutic approach for effective protection of myocardium from reperfusion injury after transplantation.

Pacemaker dependency after isolated aortic valve replacement: do conductance disorders recover over time?

OBJECTIVES Permanent pacemaker (PPM) implantation is required in 3-8% of all patients undergoing aortic valve replacement (AVR). Our aim was to evaluate long-term PPM dependency and recovery of atrioventricular (AV) conduction disorders during follow-up in these patients. METHODS Since January 1997, a total of 2106 consecutive patients underwent isolated AVR at our institution. Of these, 138 patients (6.6%, 72 female, median age 71 (37-89) years) developed significant conduction disorders leading to PPM implantation postoperatively. Preoperative ECG showed normal sinus rhythm (n = 64), first degree AV block (n = 19), left bundle branch block (n = 13), right bundle branch block (n = 16), left anterior hemiblock (n = 14) and AV block with ventricular escape rhythm (n = 10). Atrial fibrillation was present in 23 patients. Pacemakers were implanted after a median of 7 (1-30) days following AVR. PPM dependency was analysed by ECG and pacemaker check during follow-up. RESULTS A total of 45 of 138 patients with postoperative PPM Implantation died during a mean follow-up time of 5.3 ± 4.7 years. A further 9 patients were lost to follow-up. Long-term survivals at 1, 5 and 10 years were 88%, 79% and 59%, respectively. Only 8 (10%) of 84 survivors were no longer pacemaker-dependent. The majority of patients (n = 66, 79%) required permanent ventricular stimulation, and the remaining 10 (13%) showed intermittent stimulation with a mean ventricular stimulation fraction of 73% (22-98%). CONCLUSIONS The majority of patients do not recover from AV conduction disorders after AVR. Since higher-grade AV blocks expose patients to a high risk of sudden death after surgery, we recommend early implantation of permanent pacemaker.

Acute Treatment of ST-Segment-Elevation Myocardial Infarction: Is There a Role for the Cardiac Surgeon?

BACKGROUND Several attempts from single institutions to treat acute myocardial infarctions with bypass surgery never reached widespread acceptance in the cardiology and surgical community. Owing to a variety of new surgical techniques, this old dogma has to be reconsidered under the light of patient-adjusted optimal treatment algorithms. METHODS Between August 2002 and August 2007, 112 patients, mean age of 66 years (range, 41 to 85 years), underwent emergency coronary artery bypass grafting (untreatable or rejected by the referring cardiologists within 48 hours after onset of symptoms). Thirty-seven patients (33%) exhibited cardiogenic shock, and 18 (16%) had prior cardiopulmonary resuscitation. Preoperative support by intraaortic balloon pump was initiated in only 10%, and 65% had left main stem stenosis. RESULTS All patients showed a significant elevation of cardiac markers (creatine kinase-MB) and ST-segment elevation. The mean number of grafts was 2.4 (range, 1 to 4). The cardiopulmonary bypass time ranged from 48 to 261 minutes. Intraaortic balloon pump for weaning from extracorporeal circulation was used in 42 patients (38%); 3 patients needed extracorporeal membrane oxygenation support. Postoperative complications included rethoracotomy for bleeding in 4% and stroke in 2%. Thirty-day mortality was 20% in the whole group, 30% in the group with cardiogenic shock, and 15% in those without hemodynamic deterioration (p = 0.044). The multivariate analysis revealed the preoperative need for catecholamines as the only risk factor for 30-day mortality (odds ratio, 6.4; 95% confidence interval, 2 to 21; p = 0.002). CONCLUSIONS Emergency coronary artery bypass grafting in patients with acute myocardial infarction can be performed with acceptable results, especially in those without cardiogenic shock. Therefore, operative revascularization should not be considered only as a rescue therapy.

Homocysteine: A treatable risk factor for allograft vascular disease after heart transplantation?

Growing evidence suggests that elevated total plasma homocysteine (tHCY) levels are associated with cardiac allograft vasculopathy following heart transplantation. To assess the effect of folic acid supplementation on tHCY levels, we performed a prospective study in a cohort of 69 patients (7.0 +/- 3.2 years after heart transplantation; mean age, 55.0 +/- 9.6 years; 61 male) treated with 5 mg folic acid/day (n = 34) vs no medication (n = 35). Therapy with folic acid resulted in significantly decreased tHCY levels, from 22.6 +/- 9.6 micromol/liter to 17.3 +/- 5.5 micromol/liter (p = 0.001) within 3 months, whereas values in the control group remained unchanged. We conclude that folic acid supplementation (5 mg per day) provides a simple and effective measure to lower elevated tHCY levels in heart transplant recipients.

Treatment of patients with recurrent or persistent infection of cardiac implantable electronic devices.

BACKGROUND Increasing rates of bacterial infections in device therapy of cardiac rhythm disturbances pose a clinical problem. Radical surgical treatment yields the best long-term results but is frequently preceded by conservative treatment or limited surgical procedures leading to an unnecessary long treatment course. Recurrence/persistence of infection then potentially poses an even more serious clinical problem. METHODS AND RESULTS A total of 192 consecutive explantation procedures were performed for cardiac implantable electronic device (CIED) infections over a 10 year period. Forty-nine cases followed recurrence of infection subsequent to prior surgical treatment for device infection. Differences in patient/disease characteristics and outcome were looked for in recurrent as compared to primary infections (referral mode) to identify a potential requirement for adjusting treatment in recurrence. With a minimum follow-up of 24 months, 98% eradication of infection was observed independent of referral mode. Differences between primary and recurrent infection essentially reflected the primary presenting clinical picture-chronic smouldering vs. acute systemic infection. Various parameters that follow from this differentiation are significantly different between the groups. There was however no difference in outcome in terms of mortality and rate of recurrence. In addition, the parameters of the extraction procedure did not differ considerably. CONCLUSION Despite significant differences in baseline and disease characteristics between primary and recurrent CIED infection, a standardized radical protocol results in an equally high success rate in eradicating infection in both groups. Nevertheless, direct and un-delayed referral of patients with suspected CIED infection to specialized centres is recommended as it saves time for the patient.

Substantial Early Loss of Induced Pluripotent Stem Cells Following Transplantation in Myocardial Infarction

The limited success of cardiac stem cell therapy has lately generated discussion regarding its effectiveness. We hypothesized that immediate cell loss after intramyocardial injection significantly obscures the regenerative potential of stem cell therapy. Therefore, our aim was to assess the distribution and quantity of induced pluripotent stem cells after intramyocardial delivery using in vivo bioluminescence analysis. In this context, we wanted to investigate if the injection of different cell concentrations would exert influence on cardiac cell retention. Murine-induced pluripotent stem cells were transfected for luciferase reporter gene expression and transplanted into infarcted myocardium in mice after left anterior descending coronary artery ligation. Cells were delivered constantly in aqueous media (15 μL) in different cell concentrations (group A, n = 10, 5.0 × 10(5) cells; group B, n = 10, 1.0 × 10(6) cells). Grafts were detected using bioluminescence imaging. Organ explants were imaged 10 min after injection to quantify early cardiac retention and cell biodistribution. Bioluminescence imaging showed a massive early displacement from the injection site to the pulmonary circulation, leading to lung accumulation. Mean cell counts of explanted organs in group A were 7.51 × 10(4) ± 4.09 × 10(3) (heart), 6.44 × 10(4) ± 2.48 × 10(3) (left lung), and 8.06 × 10(5) ± 3.61 × 10(3) (right lung). Respective cell counts in group B explants were 1.69 × 10(5) ± 7.69 × 10(4) (heart), 2.11 × 10(5) ± 4.58 × 10(3) (left lung), and 3.25 × 10(5) ± 9.35 × 10(3) (right lung). Applying bioluminescence imaging, we could unveil and quantify massive early cardiac stem cell loss and pulmonary cell accumulation following intramyocardial injection. Increased injection concentrations led to much higher intracardiac cell counts; however, pulmonary biodistribution of transplanted cells still persisted. Therefore, we recommend applying tissue engineering techniques for cardiac stem cell transplantations in order to improve cardiac retention and limit biodistribution.

Laser-supported CD133+ cell therapy in patients with ischemic cardiomyopathy: initial results from a prospective phase I multicenter trial.

Objectives This study evaluates the safety, principal feasibility and restoration potential of laser-supported CD133+ intramyocardial cell transplantation in patients with ischemic cardiomyopathy. Methods Forty-two patients with severe ischemic cardiomyopathy (left ventricular ejection fraction (LVEF) >15% and <35%) were included in this prospective multicenter phase I trial. They underwent coronary artery bypass grafting (CABG) with subsequent transepicardial low-energy laser treatment and autologous CD133+ cell transplantation, and were followed up for 12 months. To evaluate segmental myocardial contractility as well as perfusion and to identify the areas of scar tissue, cardiac MRI was performed at 6 months and compared to the preoperative baseline. In addition, clinical assessment comprising of CCS scoring, blood and physical examination was performed at 3, 6 and 12 months, respectively. Results Intraoperative cell isolation resulted in a mean cell count of 9.7±1.2×106. Laser treatment and subsequent CD133+ cell therapy were successfully and safely carried out in all patients and no procedure-related complications occurred. At 6 months, the LVEF was significantly increased (29.7±1.9% versus 24.6±1.5% with p = 0.004). In addition, freedom from angina was achieved, and quality of life significantly improved after therapy (p<0.0001). Interestingly, an extended area of transmural delayed enhancement (>3 myocardial segments) determined in the preoperative MRI was inversely correlated with a LVEF increase after laser-supported cell therapy (p = 0.024). Conclusions This multicenter trial demonstrates that laser-supported CD133+ cell transplantation is safe and feasible in patients with ischemic cardiomyopathy undergoing CABG, and in most cases, it appears to significantly improve the myocardial function. Importantly, our data show that the beneficial effect was significantly related to the extent of transmural delayed enhancement, suggesting that MRI-guided selection of patients is mandatory to ensure the effectiveness of the therapy. Trial Registration: EudraCT 2005-004051-35) Controlled-Trials.com ISRCTN49998633