Cris Ullmann

Effects of autologous bone marrow stem cell transplantation on beta-adrenoceptor density and electrical activation pattern in a rabbit model of non-ischemic heart failure

BackgroundSince only little is known on stem cell therapy in non-ischemic heart failure we wanted to know whether a long-term improvement of cardiac function in non-ischemic heart failure can be achieved by stem cell transplantation.MethodsWhite male New Zealand rabbits were treated with doxorubicine (3 mg/kg/week; 6 weeks) to induce dilative non-ischemic cardiomyopathy. Thereafter, we obtained autologous bone marrow stem cells (BMSC) and injected 1.5–2.0 Mio cells in 1 ml medium by infiltrating the myocardium via a left anterolateral thoracotomy in comparison to sham-operated rabbits. 4 weeks later intracardiac contractility was determined in-vivo using a Millar catheter. Thereafter, the heart was excised and processed for radioligand binding assays to detect β1- and β2-adrenoceptor density. In addition, catecholamine plasma levels were determined via HPLC. In a subgroup we investigated cardiac electrophysiology by use of 256 channel mapping.ResultsIn doxorubicine-treated animals β-adrenoceptor density was significantly down-regulated in left ventricle and septum, but not in right ventricle, thereby indicating a typical left ventricular heart failure. Sham-operated rabbits exhibited the same down-regulation. In contrast, BMSC transplantation led to significantly less β-adrenoceptor down-regulation in septum and left ventricle. Cardiac contractility was significantly decreased in heart failure and sham-operated rabbits, but was significantly higher in BMSC-transplanted hearts. Norepinephrine and epinephrine plasma levels were enhanced in heart failure and sham-operated animals, while these were not different from normal in BMSC-transplanted animals. Electrophysiological mapping revealed unaltered electrophysiology and did not show signs of arrhythmogeneity.ConclusionBMSC transplantation improves sympathoadrenal dysregualtion in non-ischemic heart failure.

Functional, metabolic, and morphological aspects of continuous, normothermic heart preservation: effects of different preparation and perfusion techniques.

Continuous blood perfusion of donor hearts for transplantation has been the focus of an increasing amount of research, but the optimal preparation and perfusion techniques have not been clearly defined. Therefore, we investigated the effectiveness of different preservation strategies using continuous, normothermic heart perfusion after donor heart harvesting. Hearts of 12 pigs were randomly assigned to two groups receiving a constant pressure perfusion in a modified Langendorff system after different preparation techniques. In Group 1, six hearts were arrested with Bretschneider HTK cardioplegia (4 degrees C) and then reperfused with a circulating pressure of 80 to 90 mmHg using leukocyte depleted autologous blood. In Group 2, beating hearts of six pigs were explanted while being perfused, without cardioplegic arrest. Post-harvesting perfusion was similar to Group 1 except for a lower circulating pressure (40-50 mm Hg). At different time points (baseline and 1, 6, and 12 h after reperfusion), myocardial biopsies were taken, and contractility was assessed by measuring the maximum rate of left ventricular pressure rise (Deltap/Deltat (max)). Adenosine triphosphate (ATP) concentration was measured in all biopsies using a bioluminescence technique. Additionally, ultrastructural alterations were investigated using electron microscopy. Hypothermic cardioplegia and a higher reperfusion pressure (Group 1) were associated with an earlier and sharper decline in contractile function and intracellular ATP concentration. Ultrastructural alterations in Group 1 appeared earlier and were more distinctive than in Group 2. Endothelial ultrastructure, in particular, was better preserved in Group 2. Significant alterations were present in both groups after 12 h of perfusion but were more severe in Group 1. Blood perfusion provides protection against severe ischemic damage for a limited time. The use of a lower perfusion pressure, as well as avoiding cardioplegia and hypothermia, led to significantly better and longer preservation of perfused hearts.

Cerebral protection during controlled hypoperfusion in a piglet model: comparison of moderate (25°C) versus deep (18°C) hypothermia at various flow rates using intraoperative measurements and ex vivo investigation.

BACKGROUND During surgical correction of complex cardiac anomalies, some degree of hypoperfusion may be required. The aim of this study was to evaluate the effectiveness and safety of controlled cerebral hypoperfusion at moderate (25°C) versus deep (18°C) hypothermia. METHODS In this study, 56 female piglets (9.4 ± 0.8 kg, 3-4 weeks old) received cardiopulmonary bypass (CPB) at 25, 50, or 100% of the standard flow rate for 60 minutes of cardioplegic cardiac arrest. Body temperature was kept at 18, 25, and 37°C. Routine hemodynamic and functional parameters were measured online until 4 hours of reperfusion. Immunohistology was used to quantify heat shock protein 70 (HSP70) and nitrotyrosine (NO-Tyr) levels in the hippocampus; high-performance liquid chromatography was used to quantify jugular venous blood malondialdehyde (MDA) levels. RESULTS Reduced CPB flow led to significant reduction of mean arterial pressure by 79%, reduction of jugular venous oxygen saturation (SvO2) by 47%, reduction of carotid blood flow by 92%, and increase of serum lactate by 350%. All these changes were significantly enhanced in the 37°C versus the 25 and the 18°C groups. Regional oxygen saturation (rSO2) was significantly reduced in the 37°C low flow groups. HSP70, NO-Tyr, and MDA were increased in the 25 and 50% flow groups (p < 0.05). There was a significant correlation between rSO2 and SvO2 (r = 0.61) and between SvO2 and HSP70 (r = - 0.72). CONCLUSIONS Reduction in global blood flow during CPB leads to comparable biochemical changes in the hippocampus at 25 and 18°C. Regional oxygenation saturation, SvO2, and HSP70 are important parameters to evaluate the efficacy of further anti-ischemic therapies during surgical corrections.

Selective cerebral perfusion using moderate flow in complex cardiac surgery provides sufficient neuroprotection. Are children young adults

OBJECTIVE Selective cerebral perfusion (SCP) is commonly applied during the correction of complex congenital cardiac defects. In this study, we assessed the impact of different flow levels of SCP on potential brain ischaemia. METHODS Fifteen piglets (7-10 kg, age 3-4 weeks) received SCP via the right common carotid artery during cardiopulmonary bypass at 25°C for 90 min. Regular brain perfusion (1 ml/g brain weight/min), moderate hypoperfusion (0.5 ml/g/min) and extensive hypoperfusion (0.25 ml/g/min) were evaluated. Clinical parameters and tissue oxygenation index (TOI) were registered online until 3 h of reperfusion. Hematoxylin and eosin (HE) staining and immunohistological analyses for apoptosis inducing factor (AIF) and nitrotyrosine (NO-Tyr) were performed on sections of the hippocampus. RESULTS Intracerebral pressure remained stable throughout the study. Haemodynamic parameters, blood gas and lactate measurements were stable until the end of the study. Extensive hypoperfusion led to a moderate reduction of TOI. NO-Tyr immuno-positive cells were 15.7% at regular cerebral perfusion, 23.9% at moderate hypoperfusion (P = n.s.) and 46.1% at extensive hypoperfusion (P < 0.05). AIF immuno-positive nuclei were present in 8.3% of the hippocampus cells after regular perfusion, in 10.8% after moderate hypoperfusion (P = n.s.) and in 17.9% after extensive hypoperfusion (P < 0.05). CONCLUSIONS SCP using a moderate SCP flow regime demonstrates comparable results to normal brain perfusion while after extensive hypoperfusion significant morphological brain injury could be found. Thus moderate, but not extensive, hypoperfusion might have the potential to prevent perfusion-related cerebral oedema and an increasing risk of brain injury.

Limitationen bei manuell und telemanipulator-assistierten Ziel- und Präzisionsbewegungen in der endoskopischen Chirurgie am bewegten Objekt

Chirurgie am bewegten Objekt erfordert eine hohe Prazision und Zielgenauigkeit. Inzwischen sind Techniken entwickelt worden, die eine totalendoskopische Operation (z. B. am schlagenden Herzen) unter Verwendung eines Telemanipulatorsystems ermoglichen. Ziel der Studie war, die Bandbreite an Limitationen fur die manuelle und telemanipulator-assistierte Zielbewegungen zu eruieren. Methoden: Um Bedingungen, vergleichbar mit einem schlagenden Herzen, zu schaffen, ist ein endoskopischer Trainer bestehend aus einer beweglichen Platte und fixierten Kontaktpunkten entwickelt worden. Die Platte wird von 3 Servomotoren angetrieben und uber einen Computer gesteuert. Die Amplitude und die Frequenz kann unabhangig voneinander variiert werden, um verschiedene Bewegungen (Imitation eines ruhenden und schlagenden Herzens) mit unterschiedlicher Schnelligkeit zu simulieren. 20 Probanden wurden aufgefordert Kontaktpunkte auf der Platte in unterschiedlicher Reihenfolge mit steigendem Schwierigkeitsgrad (ID) zu treffen. Sowohl die Zeit zwischen den einzelnen Beruhrungen (Zielberuhrung lost Signal aus) als auch die Fehler (Kontaktpunkte werden verfehlt) wurden elektronisch gespeichert. Zusammenfassungg: Im Vergleich zu manuellen Zielbewegungen benotigt man bei telemanipulator-assisitierten Zielbewegungen am bewegten Objekt mehr Zeit und macht mehr Fehler. Bei hohen Geschwindigkeiten (Frequenz von 60/min) zeigt sich, das Zielbewegungen aufgrund der technischen Schwierigkeiten mit den momentan verfugbaren Telemanipulatoren nahezu unmoglich werden.