Circulating endothelial cells demonstrate an attenuation of endothelial damage by minimizing the extracorporeal circulation

ObjectiveDetachment of endothelial cells may represent serious injury of the endothelium after cardiopulmonary bypass. We investigated whether the extent of endothelial injury is related to the type of cardiopulmonary bypass system used (conventional or minimized) and determined circulating endothelial cells as well as von Willebrand factor and soluble thrombomodulin.MethodsTwenty patients scheduled for elective coronary bypass grafting were randomly assigned to either the minimal extracorporeal circulation system or the standard cardiopulmonary bypass. Ten healthy volunteers served as controls. Circulating endothelial cells per milliliter of full blood were perioperatively determined by immunomagnetic cell separation technique. Endothelial plasma markers were measured by enzyme-linked immunosorbent assay.ResultsPreoperative circulating endothelial cell numbers did not differ between the experimental groups, but were significantly higher than in the healthy controls (18.6 ± 5.6 vs 7.2 ± 3.8, P < .001). At 6 hours, circulating endothelial cell numbers increased significantly compared with baseline in both experimental groups and peaked at 12 hours after cardiopulmonary bypass initiation, each time with significantly lower values in the minimal extracorporeal circulation group (6 hours: 44.0 ± 9.9 vs 29.6 ± 9.8, P = .007; 12 hours: 48.1 ± 6.8 vs 31.8 ± 7.1, P < .001). Likewise, von Willebrand factor and soluble thrombomodulin postoperatively increased in both groups with a tendency toward lower levels in the minimal extracorporeal circulation group. Although circulating endothelial cells gradually declined, continually with lower numbers in the minimal extracorporeal circulation group, the endothelial plasma markers remained elevated during observation time.ConclusionsCirculating endothelial cells represent a novel marker of the intrinsic endothelial damage caused by cardiopulmonary bypass. Its analysis facilitates the evaluation of cardiopulmonary bypass modifications as the minimal extracorporeal circulation system could be proven to be less injurious to endothelium and myocardium

Cardioprotective Role of Sphingosine 1-Phosphate Receptor Agonist Fingolimod (FTY720) in Global Ischemia-Reperfusion Models

Background and purpose: Ischemic Heart Diseases (IHD) are the most common cause of morbidity and mortality. Incidence and prevalence is continuously growing. There is an escalating risk for revascularization or resuscitation in patients with IHD. Recently, it has been reported that sphingosine 1-phosphate receptor agonist plays anti-apoptotic and anti-inflammatory role in ischemia-reperfusion injury. The aim of our study is to investigate the cardioprotective effects of sphingosine 1-phosphate receptor agonist fingolimod (FTY720) in global ischemia-reperfusion injury related to the cardiac arrest, cardiopulmonary bypass, and heart transplantation. Methods: In all the three experimental studies, global ischemia-reperfusion was achieved by cardiac arrest either by Ventricular fibrillation or cardioplegia (CPB HT) in anesthetized (sodium pentobarbital, 60 mg/ml/kg i.v) and ventilated male Sprague-Dawley rats (300 - 350 g). The global ischemic period lasted 10 min in the cardiac arrest and cardioplegic arrest, but in transplantation, ischemia time was 60 min while reperfusion times were maintained for either 60 min or 24 hours. Where applicable, monitoring was done using electrocardiogram and hemodynamic data recorded at baseline, 1 hour and 24 hours of reperfusion. The level of high energy phosphates was measured. Apoptotic, inflammatory and oxidative markers were analyzed. The statistical significance was considered as p ≤ 0.05. Experimental design: In all the above mentioned protocols, 10 animals were used in each of the control and treated groups. The first study examined the cardioprotective potential of fingolimod using the following treatment strategy, treatment administered (post ischemia) immediately at the early phase of reperfusion (fingolimod 1mg/kg i.v) compared to saline controls (0.9% saline). In next two experimental models, treatment administration was done 15 min before ischemic phase (fingolimod 1mg/kg i.v.) compared to controls (0.9% saline), followed by 10 min ischemia and 60 min reperfusion in cardioplegic arrest while 60 min ischemic phase remained from heart explantation to reperfusion, and reperfusion phase lasted for 24 hours following blood and tissue collection Results: Three experimental models demonstrated significant myocardial protection in Fingolimod treated groups as compared to control groups. Hemodynamic assessment showed improved cardiac function at late phase. Reduced frequency of apoptotic cells and inflammatory mediators were found in the treated group. High energy phosphates were preserved in the treated as compared to control groups. Reactive Oxygen Species (ROS) were also attenuated in the fingolimod-treated group. Increased phosphorylation of Akt and Erk1/2 signaling pathways found in fingolimod treated group as compared to control, these are important part of Reperfusion Injury Salvage Kinase (RISK) and Survivor Activating Factor Enhancement(SAFE) pathways. Conclusions: The intravenous administration of fingolimod in global ischemia-reperfusion was cardioprotective. Fingolimod cardioprotection appears to be mediated through preservation of high energy phosphates, reduction in oxidative stress, inhibition of apoptosis and inflammation leading to preserved cardiac functions. In summary, targeting sphingosine 1-phosphate receptors modulation may offer a new potential therapeutic cardioprotective agent to attenuate myocardial damage during global myocardial ischemia and reperfusion

Microvascular Responsiveness to Cardiopulmonary Bypass

Cardiopulmonary bypass can result in multiple organ failure due to mechanisms of ischemia reperfusion injury and the systemic inflammatory response syndrome. The primary objective of this thesis was to investigate and monitor the microvasculature in cardiac surgery patients using multiple methodologies and real-time monitoring techniques. The purpose of our first study was to determine whether pulsatile blood flow during bypass improves microvascular perfusion compared to non-pulsatile flow. We found that changes in sublingual mucosal microcirculation using orthogonal polarization spectral imaging correlate with indices of thenar muscle tissue oxygen saturation and its recovery during a vascular occlusion test using near-infrared spectroscopy in both groups. There were significantly fewer normally perfused vessels, along with impaired microvascular responsiveness and elevated levels of lactate in the non-pulsatile group. Although these technologies help to better understand the pathophysiology of acute circulatory failure, a need exists for improved monitors that can continuously track real-time changes in the microcirculation. Our subsequent studies involved the application of a custom broadband continuous wave near-infrared monitor to determine the feasibility of tracking microvascular hemoglobin content as a surrogate for red blood cell (RBC) flow in skeletal muscle during non-pulsatile bypass. We measure changes in optical density at the isosbestic wavelength as an index of change in hemoglobin over time. The changes in optical density relative to baseline values were continuously monitored throughout the procedure, and showed a positive correlation with various interventions during bypass and with potentially negative outcomes. In our third study we applied continuous wavelet transform analysis to the near-infrared data to reflect the dynamic variability in RBC distribution within the microvasculature as an indicator of autoregulation. We showed signal power composition varied within and between patients at all time points, and shifting of power distribution from high to low frequency ranges, and vice versa, in relation to specific events during the procedure. These studies support the potential for clinical devices that can be easily interpreted by a clinician in real-time to guide therapeutic targets and improve clinical outcomes. Our current research and related future work is an important first step and compelling pre-requisite for such a monitor

Aspects of leucocyte and fat filtration during cardiac surgery

Na een hartoperatie treden vaak door het hele lichaam ontstekingsreacties op. Door het bloed tijdens de operatie te filteren, lopen patiënten minder risico op beschadigingen in longen, hart en hersenen, ontdekte Hans de Vries. Tijdens een hartoperatie neemt de hart-longmachine een aantal lichaamsfuncties over. Deze machine vormt door zijn grote contactoppervlak met het bloed van de patiënt een enorme prikkel voor stollings- en ontstekingsreacties. De ontstekingen kunnen het hele lichaam treffen en zorgen daar voor weefselbeschadigingen. Een sleutelrol in dit schadelijke proces spelen witte bloedlichaampjes (leukocyten) en vetdeeltjes die tijdens de operatie in de bloedbaan komen. De Vries experimenteerde met twee filters die respectievelijk leukocyten en vetdeeltjes uit het bloed verwijderen. Hij ontdekte dat er minder ontstekingsreacties en weefselbeschadigingen optreden wanneer de leukocyten worden gefilterd uit het restbloed van de hart-longmachine. De patiënten blijken dan na de operatie een betere longfunctie te hebben. Het filter vangt overigens niet alle leukocyten weg; het verwijdert vooral de geactiveerde, ziekmakende witte bloedlichaampjes. Ook een vetdeeltjesfilter zorgt voor minder ontstekingsreacties. Voor de patiënten had dit echter geen merkbare gevolgen. Vermoedelijk laat de effectiviteit van dit filter nog te wensen over.

Inhaled carbon monoxide protects time-dependently from loss of hypoxic pulmonary vasoconstriction in endotoxemic mice

Background: Inhaled carbon monoxide (CO) appears to have beneficial effects on endotoxemia-induced impairment of hypoxic pulmonary vasoconstriction (HPV). This study aims to specify correct timing of CO application, it’s biochemical mechanisms and effects on inflammatory reactions. Methods: Mice (C57BL/6; n = 86) received lipopolysaccharide (LPS, 30 mg/kg) intraperitoneally and subsequently breathed 50 ppm CO continuously during defined intervals of 3, 6, 12 or 18 h. Two control groups received saline intraperitoneally and additionally either air or CO, and one control group received LPS but breathed air only. In an isolated lung perfusion model vasoconstrictor response to hypoxia (FiO2 = 0.01) was quantified by measurements of pulmonary artery pressure. Pulmonary capillary pressure was estimated by double occlusion technique. Further, inflammatory plasma cytokines and lung tissue mRNA of nitric-oxide-synthase-2 (NOS-2) and heme oxygenase-1 (HO-1) were measured. Results: HPV was impaired after LPS-challenge (p < 0.01). CO exposure restored HPV-responsiveness if administered continuously for full 18 h, for the first 6 h and if given in the interval between the 3rd and 6th hour after LPS-challenge (p < 0.05). Preserved HPV was attributable to recovered arterial resistance and associated with significant reduction in NOS-2 mRNA when compared to controls (p < 0.05). We found no effects on inflammatory plasma cytokines. Conclusion: Low-dose CO prevented LPS-induced impairment of HPV in a time-dependent manner, associated with a decreased NOS-2 expression