Stereological assessment of the blood-air barrier and the surfactant system after mesenchymal stem cell pretreatment in a porcine non-heart-beating donor model for lung transplantation.

More frequent utilization of non-heart-beating donor (NHBD) organs for lung transplantation has the potential to relieve the shortage of donor organs. In particular with respect to uncontrolled NHBD, concerns exist regarding the risk of ischaemia/reperfusion (IR) injury-related graft damage or dysfunction. Due to their immunomodulating and tissue-remodelling properties, bone-marrow-derived mesenchymal stem cells (MSCs) have been suspected of playing a beneficial role regarding short- and long-term survival and function of the allograft. Thus, MSC administration might represent a promising pretreatment strategy for NHBD organs. To study the initial effects of warm ischaemia and MSC application, a large animal lung transplantation model was generated, and the structural organ composition of the transplanted lungs was analysed stereologically with particular respect to the blood-gas barrier and the surfactant system. In this study, porcine lungs (n = 5/group) were analysed. Group 1 was the sham-operated control group. In pigs of groups 2-4, cardiac arrest was induced, followed by a period of 3 h of ventilated ischaemia at room temperature. In groups 3 and 4, 50 × 106 MSCs were administered intravascularly via the pulmonary artery and endobronchially, respectively, during the last 10 min of ischaemia. The left lungs were transplanted, followed by a reperfusion period of 4 h. Then, lungs were perfusion-fixed and processed for light and electron microscopy. Samples were analysed stereologically for IR injury-related structural parameters, including volume densities and absolute volumes of parenchyma components, alveolar septum components, intra-alveolar oedema, and the intracellular and intra-alveolar surfactant pool. Additionally, the volume-weighted mean volume of lamellar bodies (lbs) and their profile size distribution were determined. Three hours of ventilated warm ischaemia was tolerated without eliciting histological or ultrastructural signs of IR injury, as revealed by qualitative and quantitative assessment. However, warm ischaemia influenced the surfactant system. The volume-weighted mean volume of lbs was reduced significantly (P = 0.024) in groups subjected to ischaemia (group medians of groups 2-4: 0.180-0.373 µm³) compared with the sham control group (median 0.814 µm³). This was due to a lower number of large lb profiles (size classes 5-15). In contrast, the intra-alveolar surfactant system was not altered significantly. No significant differences were encountered comparing ischaemia alone (group 2) or ischaemia plus application of MSCs (groups 3 and 4) in this short-term model.

Localization of Exogenous Mesenchymal Stem Cells in a Pig Model of Lung Transplantation.

BACKGROUND: Mesenchymal stem cells (MSCs) have a great potential for the treatment of acute lung injury. This study provides a detailed immunohistochemical and stereological analysis of the localization and distribution of exogenous MSC in a pig model of lung transplantation after intravascular or endobronchial application. METHODS: MSC derived from human bone marrow were labeled by DiI and administered intravascularly or endobronchially to the lungs of donor pigs after a period of 3 hours warm and 3 hours cold ischemia. The left lung was transplanted to a recipient pig and reperfused for 4 hours before fixation. The right donor lung was fixed for microscopic analysis directly after the ischemia time. RESULTS: After both administration routes, a similar number of exogenous MSC was found in the lungs. Within each animal, the heterogeneity of MSC distribution was high both with respect to left and right lung as well as to the different lobes of each lung. After endobronchial application, MSC were found in alveolar and bronchial/bronchiolar lumen, whereas after intravascular administration, they were mainly observed in blood vessels. CONCLUSION: Although the administration of exogenous MSC is possible by endobronchial or intravascular application, it yields a heterogeneous distribution in the lungs which may warrant strategies to improve a more homogeneous distribution.

Long-term results after lung transplantation using organs from circulatory death donors: a propensity score-matched analysis†.

OBJECTIVES: Due to organ shortage in lung transplantation (LTx), donation after circulatory death (DCD) has been implemented in several countries, contributing to an increasing number of organs transplanted. We sought to assess long-term outcomes after LTx with organs procured following circulatory death in comparison with those obtained from donors after brain death (DBD). METHODS: Between January 2007 and November 2013, 302 LTxs were performed in our institution, whereby 60 (19.9%) organs were retrieved from DCD donors. We performed propensity score matching (DCD:DBD = 1:2) based on preoperative donor and recipient factors that were significantly different in univariate analysis. RESULTS: After propensity matching, there were no statistically significant differences between the groups in terms of demographics and preoperative donor and recipient characteristics. There were no significant differences regarding intraoperative variables and total ischaemic time. Patients from the DCD group had significantly higher incidence of primary graft dysfunction grade 3 at the end of the procedure (P = 0.014), and significantly lower pO2/FiO2 ratio during the first 24 h after the procedure (P = 0.018). There was a trend towards higher incidence of the need for postoperative extracorporeal life support in the DCD group. Other postoperative characteristics were comparable. While the overall cumulative survival was not significantly different, the DCD group had significantly poorer results in terms of bronchiolitis obliterans syndrome (BOS)-free survival in the long-term follow-up. CONCLUSIONS: Long-term results after LTx with organs procured following DCD are in general comparable with those obtained after DBD LTx. However, patients transplanted using organs from DCD donors have a predisposition for development of BOS in the longer follow-up.

Dynamic Support Culture of Murine Skeletal Muscle-Derived Stem Cells Improves Their Cardiogenic Potential In Vitro.

Ischemic heart disease is the main cause of death in western countries and its burden is increasing worldwide. It typically involves irreversible degeneration and loss of myocardial tissue leading to poor prognosis and fatal outcome. Autologous cells with the potential to regenerate damaged heart tissue would be an ideal source for cell therapeutic approaches. Here, we compared different methods of conditional culture for increasing the yield and cardiogenic potential of murine skeletal muscle-derived stem cells. A subpopulation of nonadherent cells was isolated from skeletal muscle by preplating and applying cell culture conditions differing in support of cluster formation. In contrast to static culture conditions, dynamic culture with or without previous hanging drop preculture led to significantly increased cluster diameters and the expression of cardiac specific markers on the protein and mRNA level. Whole-cell patch-clamp studies revealed similarities to pacemaker action potentials and responsiveness to cardiac specific pharmacological stimuli. This data indicates that skeletal muscle-derived stem cells are capable of adopting enhanced cardiac muscle cell-like properties by applying specific culture conditions. Choosing this route for the establishment of a sustainable, autologous source of cells for cardiac therapies holds the potential of being clinically more acceptable than transgenic manipulation of cells.

Endothelial Injury Associated with Cold or Warm Blood Cardioplegia during Coronary Artery Bypass Graft Surgery.

The aim of this investigation was to analyze the impact of intermittent cold blood cardioplegia (ICC) and intermittent warm blood cardioplegia (IWC) on endothelial injury in patients referred to elective on-pump coronary artery bypass graft (CABG) surgery. Patients undergoing CABG procedures were randomized to either ICC or IWC. Myocardial injury was assessed by CK-MB and cardiac troponin T (cTnT). Endothelial injury was quantified by circulating endothelial cells (CECs), von Willebrand factor (vWF), and soluble thrombomodulin (sTM). Perioperative myocardial injury (PMI) and major adverse cardiac events (MACE) were recorded. Demographic data and preoperative risk profile of included patients (ICC: n = 32, IWC: n = 36) were comparable. No deaths, PMI, or MACE were observed. Levels of CK-MB and cTnT did not show intergroup differences. Concentrations of CECs peaked at 6 h postoperatively with significantly higher values for IWC-patients at 1 h (ICC: 10.1 ± 3.9/mL; IWC: 18.4 ± 4.1/mL; P = 0.012) and 6 h (ICC: 19.3 ± 6.2/mL; IWC: 29.2 ± 6.7/mL; P < 0.001). Concentrations of vWF (ICC: 178.4 ± 73.2 U/dL; IWC: 258.2 ± 89.7 U/dL; P < 0.001) and sTM (ICC: 3.2 ± 2.1 ng/mL; IWC: 5.2 ± 2.4 ng/mL; P = 0.011) were significantly elevated in IWC-group at 1 h postoperatively. This study shows that the use of IWC is associated with a higher extent of endothelial injury compared to ICC without differences in clinical endpoints.

Lung transplantation in chronic obstructive pulmonary disease: long-term survival, freedom from bronchiolitis obliterans syndrome, and factors influencing outcome.

OBJECTIVES: Lung transplantation (LTx) remains the definitive treatment for end-stage lung failure, whereas chronic obstructive pulmonary disease (COPD) represents one of the main diagnoses leading to the indication for a transplant. We sought to assess long-term outcomes after LTx in patients diagnosed with COPD and analyze factors influencing outcome in this frequent patient cohort. METHODS: Between January 2007 and November 2013, a total of 88 LTx were performed in patients with COPD in our institution. Patients with emphysema associated with alpha1-antitrypsin deficiency were excluded from this observation. The study design was a retrospective review of the prospectively collected data. A large number of pre-, intra-, and postoperative variables were analyzed including long-term survival and freedom from bronchiolitis obliterans syndrome (BOS). Furthermore, impact of different variables on survival was analyzed. RESULTS: Preoperative donor data indicated a large proportion of marginal donors. While the overall cumulative survival after six yr was 57.4%, the results in terms of BOS-free survival in long-term follow-up were 39.7% after six yr. Patients with COPD were also associated with a low incidence (2.3%) of the need for postoperative extracorporeal life support (ECLS). CONCLUSIONS: Long-term results after LTx in patients with COPD are acceptable with excellent survival, freedom from BOS, and low use of ECLS postoperatively despite permanently increasing proportion of marginal organs used.

Preconditioning of skeletal myoblast-based engineered tissue constructs enables functional coupling to myocardium in vivo.

OBJECTIVE: Skeletal myoblasts fuse to form functional syncytial myotubes as an integral part of the skeletal muscle. During this differentiation process, expression of proteins for mechanical and electrical integration is seized, which is a major drawback for the application of skeletal myoblasts in cardiac regenerative cell therapy, because global heart function depends on intercellular communication. METHODS: Mechanically preconditioned engineered tissue constructs containing neonatal mouse skeletal myoblasts were transplanted epicardially. A Y-chromosomal specific polymerase chain reaction (PCR) was undertaken up to 10 weeks after transplantation to confirm the presence of grafted cells. Histologic and electrophysiologic analyses were carried out 1 week after transplantation. RESULTS: Cells within the grafted construct expressed connexin 43 at the interface to the host myocardium, indicating electrical coupling, confirmed by sharp electrode recordings. Analyses of the maximum stimulation frequency (5.65 ± 0.37 Hz), conduction velocity (0.087 ± 0.011 m/s) and sensitivity for pharmacologic conduction block (0.736 ± 0.080 mM 1-heptanol) revealed effective electrophysiologic coupling between graft and host cells, although significantly less robust than in native myocardial tissue (maximum stimulation frequency, 11.616 ± 0.238 Hz, P < .001; conduction velocity, 0.300 ± 0.057 m/s, P < .01; conduction block, 1.983 ± 0.077 mM 1-heptanol, P < .001). CONCLUSIONS: Although untreated skeletal myoblasts cannot couple to cardiomyocytes, we confirm that mechanical preconditioning enables transplanted skeletal myoblasts to functionally interact with cardiomyocytes in vivo and, thus, reinvigorate the concept of skeletal myoblast-based cardiac cell therapy.

First experience with the Synergy Micro-Pump in patients in INTERMACS class 1-2 as a bridge to transplantation: pushing the limits?

The Synergy Micro-pump is the smallest implantable left ventricular assist device (LVAD) and provides partial flow support up to 4.25 L/min. It was shown that early intervention with this device can provide substantial benefits to patients with severe heart failure not yet sick enough for a full-support LVAD. However, as it can be inserted via small incisions with no need for sternotomy or cardiopulmonary bypass, it might be beneficial for selected high-risk patients. The aim of this study was to evaluate the efficacy of the Synergy Micro-pump in patients in INTERMACS class 1-2. From February 2012 to August 2013, 13 patients with severe heart failure were supported with the Synergy Pocket Micro-pump. Patients were divided into two groups according to INTERMACS class: the high-risk group (INTERMACS class 1-2) and the low-risk group (INTERMACS class 3-4). There were seven patients in INTERMACS class 1-2 and six in INTERMACS class 3-4. Patient demographics, perioperative characteristics, and postoperative outcomes were compared. There were no statistically significant differences in patient demographics, and mean support time was 108 ± 114 days in the high-risk group and 238 ± 198 days in the low-risk group. Also, there were no significant differences in perioperative characteristics or in the rate of postoperative adverse events. The overall survival was comparable between the two groups (one late death in each group, log-rank P = 0.608). Two patients from the high-risk group were upgraded to a full-support LVAD (P = 0.462) after 65 ± 84.9 days of mean support. One patient from the high-risk group and two patients from the low-risk group were successfully transplanted (P = 0.559). The use of the Synergy Micro-pump in INTERMACS 1-2 patients is feasible and is associated with similar postoperative outcome as in patients in INTERMACS 3-4. Carefully selected patients with severe heart failure could benefit due to the small size of the pump; however, further studies and medium-term follow-up are required.

Risk factors predictive of one-year mortality after lung transplantation.

OBJECTIVES: Lung transplantation (LTx) is a life-saving therapy for patients with end-stage lung disease. However, there remains a significant postoperative complication rate and mortality in this extreme patient group. The aim of the present study was to identify donor, recipient and perioperative risk factors for one-year mortality after LTx. METHODS: A total of 252 LTxs were performed in our institution between 2007 and 2013. Donor and recipient demographics and clinical characteristics of 1-year survivors and non-survivors were collected and compared retrospectively. Multivariate logistic regression analysis was performed on univariate predictors for 1-year mortality with an entry criterion of P < 0.05. RESULTS: Multivariate analysis revealed female-to-male transplantation (95% CI: 0.088-0.767; P = 0.015), lower pO2/FiO2-ratio at 72 h postoperatively (95% CI: 0.988-0.999; P = 0.024), need for postoperative extracorporeal membrane oxygenation (ECMO) support (95% CI: 0.035-0.658; P = 0.012) and on-pump technique (95% CI: 0.007-0.944; P = 0.045) as the only independent predictors for 1-year mortality. Mainly unplanned intraoperative conversion to cardiopulmonary bypass contributed to poorer survival in patients who underwent LTx using cardiopulmonary bypass (P < 0.001). CONCLUSIONS: Our results show that the unplanned use of CPB (conversion from off- to on-pump) might adversely affect outcome after LTx. Also, the negative impact of female-to-male transplantation should not be underestimated during recipient selection. Furthermore, poor early postoperative oxygenation, particularly with the need for extracorporeal oxygenation, might be a very strong negative prognostic factor after LTx.

Mesenchymal stem cell pretreatment of non-heart-beating-donors in experimental lung transplantation.

BACKGROUND: Lung transplantation (LTx) is still limited by organ shortage. To expand the donor pool, lung retrieval from non-heart-beating donors (NHBD) was introduced into clinical practice recently. However, primary graft dysfunction with inactivation of endogenous surfactant due to ischemia/reperfusion-injury is a major cause of early mortality. Furthermore, donor-derived human mesenchymal stem cell (hMSC) expansion and fibrotic differentiation in the allograft results in bronchiolitis obliterans syndrome (BOS), a leading cause of post-LTx long-term mortality. Therefore, pretreatment of NHBD with recipient-specific bone-marrow-(BM)-derived hMSC might have the potential to both improve the postischemic allograft function and influence the long-term development of BOS by the numerous paracrine, immunomodulating and tissue-remodeling properties especially on type-II-pneumocytes of hMSC. METHODS: Asystolic pigs (n = 5/group) were ventilated for 3 h of warm ischemia (groups 2-4). 50x106 mesenchymal-stem-cells (MSC) were administered in the pulmonary artery (group 3) or nebulized endobronchially (group 4) before lung preservation. Following left-lung-transplantation, grafts were reperfused, pulmonary-vascular-resistance (PVR), oxygenation and dynamic-lung-compliance (DLC) were monitored and compared to control-lungs (group 2) and sham-controls (group 1). To prove and localize hMSC in the lung, cryosections were counter-stained. Intra-alveolar edema was determined stereologically. Statistics comprised ANOVA with repeated measurements. RESULTS: Oxygenation (p = 0.001) and PVR (p = 0.009) following endovascular application of hMSC were significantly inferior compared to Sham controls, whereas DLC was significantly higher in endobronchially pretreated lungs (p = 0.045) with overall sham-comparable outcome regarding oxygenation and PVR. Stereology revealed low intrapulmonary edema in all groups (p > 0.05). In cryosections of both unreperfused and reperfused grafts, hMSC were localized in vessels of alveolar septa (endovascular application) and alveolar lumen (endobronchial application), respectively. CONCLUSIONS: Preischemic deposition of hMSC in donor lungs is feasible and effective, and endobronchial application is associated with significantly better DLC as compared to sham controls. In contrast, transvascular hMSC delivery results in inferior oxygenation and PVR. In the long term perspective, due to immunomodulatory, paracrine and tissue-remodeling effects on epithelial and endothelial restitution, an endobronchial NHBD allograft-pretreatment with autologous mesenchymal-stem-cells to attenuate limiting bronchiolitis-obliterans-syndrome in the long-term perspective might be promising in clinical lung transplantation. Subsequent work with chronic experiments is initiated to further elucidate this important field.

Outcomes after implantation of partial-support left ventricular assist devices in inotropic-dependent patients: Do we still need full-support assist devices?

OBJECTIVES: Partial-support left ventricular assist devices (LVADs) represent a novel strategy for heart failure treatment. The Synergy Pocket Micro-pump (HeartWare Inc, Framingham, Mass), the smallest surgically implanted long-term LVAD, provides partial flow up to 4.25 L/min and was primarily designed for "less sick" patients with severe heart failure. This device is implanted minimally invasively without sternotomy or cardiopulmonary bypass. Early implantation in patients with Interagency Registry for Mechanically Assisted Circulatory Support class 4 and higher was shown to be feasible and associated with significantly improved hemodynamics and quality of life. The aim of this study was to present our experience with implementation of long-term partial circulatory support as a bridge to transplantation in patients with more advanced heart failure who were dependent preoperatively on inotropic support or intra-aortic balloon pump. METHODS: In this observational study, only inotropic or intra-aortic balloon pump-dependent patients with end-stage heart failure were included (n = 12). These patients underwent Synergy device implantation between February 2012 and August 2013. RESULTS: The mean preoperative Interagency Registry for Mechanically Assisted Circulatory Support class was 2.17 ± 0.84 (class 1, 25%; class 2, 33%; class 3, 42%). The mean age was 46 ± 15 years, and 33% were female. Preoperatively, 4 patients (33%) had at least 1 previous sternotomy, 3 patients (25%) were supported with a balloon pump, 1 patient (8%) had a previous full-support LVAD, and 4 patients (33%) had cerebrovascular events in the past. After device implantation, there were no right ventricular failures, device-related infections, hemorrhagic strokes, arterial or venous thromboembolisms, or worsenings of aortic and mitral regurgitation observed over the follow-up. The mean follow up was 174 ± 171 days (range, 5-764 days; cumulative, 3199 days). One patient (8%) died, 3 patients (25%) successfully underwent transplantation, 1 device (8%) was explanted after myocardial recovery, and 5 patients (42%) are still on ongoing support. Two patients (17%) were upgraded to a full-support LVAD after 65 days of mean support. A total of 11 of 12 patients (92%) were discharged from the hospital and are presently alive. Left ventricular end-diastolic diameter was significantly reduced 3 months after device implantation. CONCLUSIONS: Partial LVAD support may be clinically efficacious in inotropic and intra-aortic balloon pump-dependent patients. On the basis of our experience and evidence of previous research, such patients may benefit from minimally invasive access, no need for sternotomy and cardiopulmonary bypass, a short implantation time, an easy exchange if necessary, and a lower risk of subsequent heart transplantation. Because the implantation is performed without sternotomy, device upgrade is feasible with a comparatively low operative risk and good clinical outcome. Our preliminary results show that partial-support devices may have the potential to replace full-support LVADs in the near future.

Outcomes after different non-sternotomy approaches to left single-vessel revascularization: a comparative study with up to 10-year follow-up.

OBJECTIVES: Various non-sternotomy approaches have been used for left internal mammary artery (LIMA) grafting in left single-vessel revascularization. The aim of this study was to evaluate the impact of three different non-sternotomy techniques on long-term outcomes after left single-vessel revascularization. METHODS: A total of 502 patients having single-vessel LAD disease treated from April 2003 to May 2013 by minimally invasive direct coronary artery bypass grafting (MIDCAB), endoscopically assisted coronary artery bypass grafting (EACAB) or robotically assisted direct coronary artery bypass grafting (RADCAB) were reviewed. In all cases, distal anastomoses were performed through anterolateral minithoracotomy incisions. In-hospital and long-term (10-year) outcomes were compared using standard and propensity score-adjusted analyses. RESULTS: One hundred and eighty-nine patients had MIDCAB, 76 had EACAB and 236 had RADCAB. After propensity score matching, RADCAB patients had significantly longer operative duration (P < 0.001), whereas MIDCAB and RADCAB patients had significantly higher incidence of postoperative angina over the follow-up (P = 0.034). The groups were comparable regarding in-hospital mortality and reintervention rate as well as incidence of myocardial infarction, reoperations, reinterventions and cardiac death. All groups showed comparable long-term survival (P = 0.943). CONCLUSIONS: MIDCAB, EACAB and RADCAB are associated with similar long-term survival and incidence of major adverse cardiac events (MACEs) in single-vessel surgical revascularization. However, the endoscopic approach was found to be free from the disadvantages of longer operating duration observed in RADCAB or higher incidence of angina and shorter freedom from MACEs observed in both MIDCAB and RADCAB groups.

A novel treatment strategy of new onset atrial fibrillation after cardiac surgery: an observational prospective study.

OBJECTIVE: The aim of this prospective observational study was to evaluate the efficiency of a new escalating treatment strategy with vernakalant, flecainide and electrical cardioversion (EC) in patients with new onset atrial fibrillation (AF) after cardiac surgery. MATERIAL AND METHODS: 24 patients with new onset AF after aortic valve surgery, coronary artery bypass surgery or combined procedures were evaluated in this study. Additional including criteria were age between 18 and 80, duration of AF less than four days, body weight less than 100 kg and no previous treatment with class I or III antiarrhythmic drugs. Exclusion criteria were poor left ventricular ejection fraction (LVEF < 40%) and history of myocardial infarction within 30 days. The patients were divided into converters and non-converters according to their response to combination treatment with vernakalant and flecainide, and the groups were compared. RESULTS: The mean age of the population was 69.6 ± 6.3 years and 26.1% of patients were female. There were no statistically significant differences between the two groups in terms of height, weight, gender distribution, comorbidities, preoperative medication, left ventricular function and left atrium diameter. Interventricular septum (IVS) in the non-converted group was significantly thicker compared to the converted group: 14.0 ± 1.00 vs. 10.40 ± 2.59 mm (p = 0.036). While 14 patients (60.9%) were successfully converted into stable sinus rhythm by pharmacological treatment with vernakalant and flecainide, 9 patients (39.1%, non-converted group) remained in AF. However, seven of them could be converted after additional EC. CONCLUSION: The combination of vernakalant and flecainide improves the conversion rate into a stable sinus rhythm in postcardiotomy patients with new onset AF compared to single drug therapy. Furthermore it might be an excellent precondition for successful EC in patients who are not converted after using both antiarrhtythmic drugs. Furthermore, left ventricular hypertrophy might be a potential negative predictor of successful pharmacological cardioversion.

Effects of exogenous surfactant on the non-heart-beating donor lung graft in experimental lung transplantation - a stereological study.

The use of non-heart-beating donor (NHBD) lungs may help to overcome the shortage of lung grafts in clinical lung transplantation, but warm ischaemia and ischaemia/reperfusion injury (I/R injury) resulting in primary graft dysfunction represent a considerable threat. Thus, better strategies for optimized preservation of lung grafts are urgently needed. Surfactant dysfunction has been shown to contribute to I/R injury, and surfactant replacement therapy is effective in enhancing lung function and structural integrity in related rat models. In the present study we hypothesize that surfactant replacement therapy reduces oedema formation in a pig model of NHBD lung transplantation. Oedema formation was quantified with (SF) and without (non-SF) surfactant replacement therapy in interstitial and alveolar compartments by means of design-based stereology in NHBD lungs 7 h after cardiac arrest, reperfusion and transplantation. A sham-operated group served as control. In both NHBD groups, nearly all animals died within the first hours after transplantation due to right heart failure. Both SF and non-SF developed an interstitial oedema of similar degree, as shown by an increase in septal wall volume and arithmetic mean thickness as well as an increase in the volume of peribron-chovascular connective tissue. Regarding intra-alveolar oedema, no statistically significant difference could be found between SF and non-SF. In conclusion, surfactant replacement therapy cannot prevent poor outcome after prolonged warm ischaemia of 7 h in this model. While the beneficial effects of surfactant replacement therapy have been observed in several experimental and clinical studies related to heart-beating donor lungs and cold ischaemia, it is unlikely that surfactant replacement therapy will overcome the shortage of organs in the context of prolonged warm ischaemia, for example, 7 h. Moreover, our data demonstrate that right heart function and dysfunctions of the pulmonary vascular bed are limiting factors that need to be addressed in NHBD.

Less invasive coronary artery revascularization with a minimized extracorporeal circulation system: preliminary results of a comparative study with off-pump-procedures.

BACKGROUND: Coronary-artery-bypass-grafting (CABG) with conventional extracorporeal circulation (CECC) is associated with adverse effects such as systemic inflammatory response leading to a decrease in systemic vascular resistance and hemodynamic instability. Modern "less invasive" procedures have been established recently which potentially avoid negative side effects of CECC. The aim of this study was to compare perioperative outcome following coronary revascularization using either a minimized extracorporeal circuit (Mini-HLM) or off-pump technique (OPCAB). METHODS: In this prospective ethics-approved trial, 120 patients referred for CABG were randomly assigned either to off-pump coronary artery bypass (OPCAB) or to a Mini-HLM procedure. Patient demographics, preoperative characteristics and extensive postoperative outcome were analyzed for both groups. Hemodynamic data were measured at seven time points perioperatively. RESULTS: Operation-time was longer in the Mini-HLM group (178,3 ± 32,9 min) compared to OPCAB (133,2 ± 32,7 min, p < 0,001) with higher graft numbers in Mini-HLM group (3,11 ± 0,7 vs. 1,78 ± 0,7, p < 0.001). There were no significant differences in perioperative hemodynamic criteria, catecholaminergic support, hospital (p = 0,534) and intensive care unit stay (p = 0,880), ventilation time (p = 0,113), blood loss (p = 0,570), transfusion requirements, postoperative atrial fibrillation rate (p = 0,706) and neurocognitive disturbance (p = 0,297). No deaths and no myocardial infarctions were observed. CONCLUSIONS: Coronary revascularisation with Mini-HLM represents a suitable and "less invasive" procedure which achieves all benefits of OPCAB but may allow for less demanding revascularisation than OPCAB in special patients with complex coronary anatomy and can therefore be used both on a routine basis and in all "conversion" cases of OPCAB.

Surfactant application in experimental lung transplantation.

BACKGROUND: Non-heart-beating donor (NHBD) utilization can significantly increase the limited donor lung pool. However, optimal preservation of organ function is crucial as the development of ischemia/reperfusion injury (IRI) can result in severe surfactant inactivation. Exogenic surfactant application is effective in prevention and therapy of IRI. Studies on optimal timing of Curosurf, including application in NHBDs, have not been done, but could help to optimize NHBD lung transplantation. METHODS: The extracorporeal screening model (ESM) included rat lungs (Sprague-Dawley, n = 5/group) preserved with Perfadex. In 3 test groups, Curosurf was administered before flush preservation (T1), after 4-hour ischemia (T2) or during reperfusion (T3). Results after extracorporeal reperfusion were compared with controls. The transplantation model (TM) consisted of asystolic pigs (n = 5/group) ventilated for 7 hours with warm ischemia (WIT, Groups 1 and 2). In Group 2, 100 mg/kg BW Curosurf was bronchoscopically administered before preservation. After 3-hour cold storage, left lung transplantation was performed and data were compared with sham control data (Group 3). RESULTS: For the ESM, T1 lung oxygenation (SurfT1 167±47.4 mm Hg) was superior to others (SurfT2 47.3±15.3 mm Hg, SurfT3 77.2±48.8 mm Hg, controls 65.5±46.2 mm Hg; p<0.02). Stereology demonstrated poorer intra-alveolar edema formation in controls (1.86±2.53% of parenchyma) compared with surfactant-treated lungs (<0.02% of parenchyma) (p<0.02). Intra-alveolar erythrocyte sequestration as an indicator of vascular leakage was significantly lower in T1 lungs (0.15±0.12% of parenchyma) compared with all other groups (>0.74% of parenchyma). For TM, mortality was 80% in the untreated group and 100% in the Curosurf group, suggesting that a 7-hour WIT is above the limit for NHBD utilization. CONCLUSIONS: Donor lung pre-treatment with endobronchial pre-preservation Curosurf offers optimal preservation quality when compared with post-ischemic application or during reperfusion and results in improved functional outcome when compared with controls. Expensive NHBD pre-treatment with Curosurf cannot improve poor allograft outcome after extended WIT and should therefore not be considered. Seven-hour WIT seems generally to be above the limits for use in NHBD lung donors.

Noninvasive in vivo tracking of mesenchymal stem cells and evaluation of cell therapeutic effects in a murine model using a clinical 3.0 T MRI.

Cardiac cell therapy with mesenchymal stem cells (MSCs) represents a promising treatment approach for end-stage heart failure. However, little is known about the underlying mechanisms and the fate of the transplanted cells. The objective of the presented work is to determine the feasibility of magnetic resonance imaging (MRI) and in vivo monitoring after transplantation into infarcted mouse hearts using a clinical 3.0 T MRI device. The labeling procedure of bone marrow-derived MSCs with micron-sized paramagnetic iron oxide particles (MPIOs) did not affect the viability of the cells and their cell type-defining properties when compared to unlabeled cells. Using a clinical 3.0 T MRI scanner equipped with a dedicated small animal solenoid coil, 10(5) labeled MSCs could be detected and localized in the mouse hearts for up to 4 weeks after intramyocardial transplantation. Weekly ECG-gated scans using T1-weighted sequences were performed, and left ventricular function was assessed. Histological analysis of hearts confirmed the survival of labeled MSCs in the target area up to 4 weeks after transplantation. In conclusion, in vivo tracking of labeled MSCs using a clinical 3.0 T MRI scanner is feasible. In combination with assessment of heart function, this technology allows the monitoring of the therapeutic efficacy of regenerative therapies in a small animal model.

Intraoperative stress in cardiac surgery: attendings versus residents.

BACKGROUND: Performing cardiac surgery is associated with stress for surgeons. We investigated stress levels of experienced surgeons and trainees during coronary artery bypass graft teaching procedures. METHODS: We assessed heart rate (HR) and sympathovagal balance (SVB) of experienced surgeons (attendings; n = 7) and residents enrolled in a training program (residents; n = 3) using a one-lead electrocardiogram during a total of 109 elective isolated coronary artery bypass graft procedures. We measured HR and SVB for baseline values at rest and at prespecified phases during the procedure in the role as primary surgeons (n = 10) and assistants (n = 9). RESULTS: All participants were healthy men with a mean age of 41.4 ± 4.3 y. For patients operated on during this study, demographic and intraoperative data were homogeneous. Compared with rest, mean HR and SVB for the whole procedure were higher for surgeons and assistants, with significant differences for HR values (surgeons, 83.7 ± 8.8 beats/min [bpm]; assistants, 85.4 ± 12.7 bpm, P < 0.05 versus 62.3 ± 5.1 bpm). Courses of HR and SVB were comparable for attending and resident groups but values were higher throughout for attendings compared with residents in their role as surgeons during the total procedure, and as assistants during cardiopulmonary bypass. Mean HR and SVB values of attendings assisting the procedure were higher compared with those of residents performing the operation. CONCLUSIONS: Surgical experience is not associated with reduced stress levels. Supervising a teaching case in cardiac surgery can be linked with more stress compared with the resident performing the procedure.

Mechanical preconditioning enables electrophysiologic coupling of skeletal myoblast cells to myocardium.

OBJECTIVE: The effect of mechanical preconditioning on skeletal myoblasts in engineered tissue constructs was investigated to resolve issues associated with conduction block between skeletal myoblast cells and cardiomyocytes. METHODS: Murine skeletal myoblasts were used to generate engineered tissue constructs with or without application of mechanical strain. After in vitro myotube formation, engineered tissue constructs were co-cultured for 6 days with viable embryonic heart slices. With the use of sharp electrodes, electrical coupling between engineered tissue constructs and embryonic heart slices was assessed in the presence or absence of pharmacologic agents. RESULTS: The isolation and expansion procedure for skeletal myoblasts resulted in high yields of homogeneously desmin-positive (97.1% ± 0.1%) cells. Mechanical strain was exerted on myotubes within engineered tissue constructs during gelation of the matrix, generating preconditioned engineered tissue constructs. Electrical coupling between preconditioned engineered tissue constructs and embryonic heart slices was observed; however, no coupling was apparent when engineered tissue constructs were not subjected to mechanical strain. Coupling of cells from engineered tissue constructs to cells in embryonic heart slices showed slower conduction velocities than myocardial cells with the embryonic heart slices (preconditioned engineered tissue constructs vs embryonic heart slices: 0.04 ± 0.02 ms vs 0.10 ± 0.05 ms, P = .011), lower maximum stimulation frequencies (preconditioned engineered tissue constructs vs embryonic heart slices: 4.82 ± 1.42 Hz vs 10.58 ± 1.56 Hz; P = .0009), and higher sensitivities to the gap junction inhibitor (preconditioned engineered tissue constructs vs embryonic heart slices: 0.22 ± 0.07 mmol/L vs 0.93 ± 0.15 mmol/L; P = .0004). CONCLUSIONS: We have generated skeletal myoblast-based transplantable grafts that electrically couple to myocardium.