Xenotransplantation of porcine islet cells as a potential option for the treatment of type 1 diabetes in the future.

Solid organ and cell transplantation, including pancreatic islets constitute the treatment of choice for chronic terminal diseases. However, the clinical use of allogeneic transplantation is limited by the growing shortage of human organs. This has prompted us to initiate a unique multi-center and multi-team effort to promote translational research in xenotransplantation to bring xenotransplantation to the clinical setting. Supported by the German Research Foundation, an interdisciplinary group of surgeons, internal medicine doctors, diabetologists, material sciences experts, immunologists, cell biologists, virologists, veterinarians, and geneticists have established a collaborative research center (CRC) focusing on the biology of xenogeneic cell, tissue, and organ transplantation. A major strength of this consortium is the inclusion of members of the regulatory bodies, including the Paul-Ehrlich Institute (PEI), infection specialists from the Robert Koch Institute and PEI, veterinarians from the German Primate Center, and representatives of influential ethical and religious institutions. A major goal of this consortium is to promote islet xenotransplantation, based on the extensive expertise and experience of the existing clinical islet transplantation program. Besides comprehensive approaches to understand and prevent inflammation-mediated islet xenotransplant dysfunction [immediate blood-mediated inflammatory reaction (IBMIR)], we also take advantage of the availability of and experience with islet macroencapsulation, with the goal to improve graft survival and function. This consortium harbors a unique group of scientists with complementary expertise under a cohesive program aiming at developing new therapeutic approaches for islet replacement and solid organ xenotransplantation.

Early prediction of cardiac allograft vasculopathy and heart transplant failure.

Early risk-prediction is essential to prevent cardiac allograft vasculopathy (CAV) and graft failure in heart transplant patients. We developed multivariate models to identify patients likely to experience CAV, severe CAV, and failure due to CAV, at 1, 5 and 10 years. A cohort of 172 patients was followed prospectively for 6.7 ± 3.9 years. Logistic regression models were developed and cross-validated using bootstrap resampling. Predictive markers of atherothrombosis (myocardial fibrin deposition, and loss of vascular antithrombin and tissue plasminogen activator) and arterial endothelial activation (intercellular adhesion molecule-1 expression) were measured in serial biopsies obtained within 3 months posttransplant. Most markers were univariately associated with outcome. Multivariate models showed that loss of tissue plasminogen activator was the dominant and, in most cases, only predictor of long-term CAV (p < 0.001), severe CAV (p < 0.001), and graft failure due to CAV (p < 0.001). The models discriminated patients having adverse outcomes, had particularly high negative predictive values (graft failure due to CAV: 99%, 99% and 95% at 1, 5 and 10 years) and predicted event incidence and time to event. Early absence of atherothrombotic risk identifies a patient subgroup that rarely develops CAV or graft failure, implying that this low-risk subgroup could possibly be followed with fewer invasive procedures.

Genetic polymorphisms of TP53 and FAS promoter modulate the progression of coronary artery disease after coronary artery bypass grafting: a gender-specific view.

INTRODUCTION: Progression of coronary artery disease (CAD) after primary coronary artery bypass grafting (CABG) is frequent and may lead to recurrent symptoms. Various data indicate that apoptosis is the main event occurring during development and progression of atherosclerotic plaque. Plaque vascular smooth muscle cells (VSMCs) are more sensitive than regular VSMCs to TP53-mediated apoptosis. METHODS: We investigated EDTA blood of 192 patients (18% female, age 60.9 ± 7.4 years) who had primary CABG more than 5 years ago. CAD progression was defined as clinical endpoints: re-operation (n = 88; 46%), catheter re-intervention (n = 58; 30%), or angina at follow-up (n = 89; 46%). Apoptotic gene polymorphisms (Toll-like receptor 2 A753G, FAS ligand C-844T, FAS promoter G-670A, TP53 Arg72Pro, and CD14 C-260T) were investigated by PCR-RFLP and compared to healthy controls (n = 200, 24% female, age 63.4 ± 5.4). Gender-specific analysis was carried out. RESULTS: Heterozygous, homozygous and wild-type expression of all five genetic polymorphisms showed almost identical distribution between patients with CAD and healthy controls. Looking at clinical endpoints, with GG expression of Toll-like receptor 2 polymorphism and GG expression of FAS promoter polymorphism, results showed a relative increased risk (p = 0.09) for recurrent symptoms and re-intervention. Patients with FAS promoter polymorphism with AA expression had an increased risk of suffering from recurrent symptoms (n = 28, p = 0.04). We found that patients with homozygous expression of TP53 polymorphisms (n = 3, all male) were prone to needing re-intervention after prior CABG (p = 0.03), but not re-operation. Over a period up to 15 years, the re-intervention rate was significantly different in homozygous genotypes of FAS LG, FAS promoter and TP53. CONCLUSIONS: Patients presenting with polymorphisms of FAS LG, FAS promoter and TP53 have an increased risk of CAD progression, as they have a higher rate of re-interventions.

Proton pump inhibitors reduce mycophenolate exposure in heart transplant recipients-a prospective case-controlled study.

This prospective study investigates the impact of proton pump inhibitors (PPI) on mycophenolic acid (MPA) pharmacokinetics in heart transplant recipients receiving mycophenolate mofetil (MMF) and tacrolimus. MPA plasma concentrations at baseline (C(0 h)), 30 min (C(0.5 h)), 1(C(1 h)) and 2 h (C(2 h)) were obtained by high-performance liquid chromatography (HPLC) in 22 patients treated with pantoprazole 40 mg and MMF 2000 mg. Measurements were repeated 1 month after pantoprazole withdrawal. A four-point limited-sampling strategy was applied to calculate the MPA area under the curve (MPA-AUC). Predose MPA concentrations with PPI were 2.6 +/- 1.6 mg/L versus 3.4 +/- 2.7 mg/L without PPI (p = ns). Postdose MPA concentrations were lower with PPI at C(0.5 h) (8.3 +/- 5.7 mg/L vs. 18.3 +/- 11.3 mg/L, p = 0.001) and C(1 h) (10.0 +/- 5.6 mg/L vs. 15.8 +/- 8.4 mg/L, p = 0.004), without significant differences at C(2 h) (8.3 +/- 6.5 mg/L vs. 7.6 +/- 3.9 mg/L). The MPA-AUC was significantly lower with PPI medication (51.2 +/- 26.6 mg x h/L vs. 68.7 +/- 30.3 mg x h/L; p = 0.003). The maximum concentration of MPA (MPA-C(max)) was lower (12.2 +/- 7.5 mg/L vs. 20.6 +/- 9.3 mg/L; p = 0.001) and the time to reach MPA-C(max) (t(max)) was longer with PPI (60.0 +/- 27.8 min vs. 46.4 +/- 22.2 min; p = 0.05). This is the first study to document an important drug interaction between a widely used immunosuppressive agent and a class of drugs frequently used in transplant patients. This interaction results in a decreased MMF drug exposure which may lead to patients having a higher risk for acute rejection and transplant vasculopathy.

Impact of polyclonal anti-thymocyte globulins on the expression of adhesion and inflammation molecules after ischemia-reperfusion injury.

BACKGROUND: Polyclonal anti-thymocyte globulins (ATGs) are immunosuppressive agents used for the treatment and prevention of acute organ rejection after transplantation. ATGs induce apoptosis and complement-mediated cell death in peripheral T-lymphocytes and have shown a reduction of leukocyte adhesion after ischemia-reperfusion (IRI). We analyzed the impact of different ATGs upon the expression of adhesion and inflammation molecules after IRI. MATERIALS AND METHODS: The major arteries and veins of the extremities of cynomolgus monkeys were surgically isolated and flushed with Ringer's lactate at 4 degrees C. After 60 min of ischemia the limbs were reperfused with matching human blood. ATGs were added to the blood 30 min prior to the reperfusion, forming four groups: Tecelac-ATG group (n=16), Fresenius(S)-ATG group (n=16), Thymoglobulin-ATG group (n=12) and a control group (n=16). Biopsies from muscular tissue were obtained after the experiments. The expression of adhesion (ICAM-1, VCAM, PECAM, CD11b, CD62E) and inflammation (IL-1, IL-6, TNF-alpha) molecules on endothelium, leukocytes, and reperfused tissue was analyzed by means of immunohistochemistry. RESULTS: The expression of the studied adhesion molecules (ICAM-1, VCAM, PECAM, CD11b, and CD62E) was significantly increased in the control group when compared with the treated groups. The expression of IL-1, IL-6, and TNF-alpha was reduced in the ATG-groups in comparison to the control group. DISCUSSION: Our results showed that ATGs caused a reduction of the expression of adhesion and inflammation molecules both in endothelium and reperfused tissue. The inhibition of the expression of molecules required for firm cellular adhesion, may contribute to decreasing cellular graft infiltration after post-ischemic reperfusion.

Cofactor requirements for nuclear export of Rev response element (RRE)- and constitutive transport element (CTE)-containing retroviral RNAs. An unexpected role for actin.

Nuclear export of proteins containing leucine-rich nuclear export signals (NESs) is mediated by the export receptor CRM1/exportin1. However, additional protein factors interacting with leucine-rich NESs have been described. Here, we investigate human immunodeficiency virus type 1 (HIV-1) Rev-mediated nuclear export and Mason-Pfizer monkey virus (MPMV) constitutive transport element (CTE)-mediated nuclear export in microinjected Xenopus laevis oocytes. We show that eukaryotic initiation factor 5A (eIF-5A) is essential for Rev and Rev-mediated viral RNA export, but not for nuclear export of CTE RNA. In vitro binding studies demonstrate that eIF-5A is required for efficient interaction of Rev-NES with CRM1/exportin1 and that eIF-5A interacts with the nucleoporins CAN/nup214, nup153, nup98, and nup62. Quite unexpectedly, nuclear actin was also identified as an eIF-5A binding protein. We show that actin is associated with the nucleoplasmic filaments of nuclear pore complexes and is critically involved in export processes. Finally, actin- and energy-dependent nuclear export of HIV-1 Rev is reconstituted by using a novel in vitro egg extract system. In summary, our data provide evidence that actin plays an important functional role in nuclear export not only of retroviral RNAs but also of host proteins such as protein kinase inhibitor (PKI).

Design and fabrication of three-dimensional scaffolds for tissue engineering of human heart valves.

We developed a new fabrication technique for 3-dimensional scaffolds for tissue engineering of human heart valve tissue. A human aortic homograft was scanned with an X-ray computer tomograph. The data derived from the X-ray computed tomogram were processed by a computer-aided design program to reconstruct a human heart valve 3-dimensionally. Based on this stereolithographic model, a silicone valve model resembling a human aortic valve was generated. By taking advantage of the thermoplastic properties of polyglycolic acid as scaffold material, we molded a 3-dimensional scaffold for tissue engineering of human heart valves. The valve scaffold showed a deviation of only +/-3-4% in height, length and inner diameter compared with the homograft. The newly developed technique allows fabricating custom-made, patient-specific polymeric cardiovascular scaffolds for tissue engineering without requiring any suture materials.

CD14(++)CD16+ monocytes but not total monocyte numbers predict cardiovascular events in dialysis patients.

Migration of monocytes into the vessel wall contributes to the onset and progression of atherosclerosis. Because monocytes are a heterogeneous population, we determined potential associations between monocyte subsets and cardiovascular events in a prospective cohort of 94 dialysis patients followed for 35 months. The incidence of cardiovascular events and death measured by Kaplan-Meier plots and flow cytometric analysis of monocyte subsets showed that total leukocyte and monocyte numbers failed to predict event-free survival. Among monocyte subsets, a high CD14(++)CD16(+) monocyte number was associated with higher rates of cardiovascular events and death. In a multivariate proportional hazards model adjusted for classical cardiovascular risk factors, patients with CD14(++)CD16(+) monocyte numbers in the top quartile were at higher risk of cardiovascular events and death compared to patients in the lowest quartile. Our study suggests that the number of CD14(++)CD16(+) monocytes was independently associated with cardiovascular events and death in a high-risk population of dialysis patients.

[Assessment of aortic stenosis after aortic valve replacement: comparative evaluation of dual-source CT and echocardiography]. / Quantitative Evaluation der Aortenklappenöffnungsfläche mit der Dual-Source-CT und Korrelation mit der 2D-Echokardiografie: Initiale Ergebnisse.

PURPOSE: To prospectively evaluate whether planimetric measurements of aortic valve area (AVA) with dual-source computed tomography (DSCT) correlate with measurements obtained by echocardiography and to correlate the amount of calcification of the aortic valve with AVA in a group of patients after aortic valve replacement. MATERIALS AND METHOD: 23 patients underwent dual-source computed tomography (DSCT) of the heart (Somatom Definition, Siemens Medical Solutions, Forchheim, Germany), without heart rate control (heart rate 52-113 beats/minute). All patients had undergone aortic valve replacement (homografts, mean time after surgery: 7+/-3 years). The AVA of the transplanted aortic valve graft was measured planimetrically by means of DSCT and compared with echocardiography as a standard of reference, to exclude post-surgical restenosis of the valve. Maximum AVA in systole planimetrically measured with CT was compared with calculated AVA values determined with the continuity equation, using transvalvular pressure gradients. The amount of calcification of the aortic valve was quantified and correlated (Spearman's R) with the AVA. To assess intra- and inter-reader reproducibility, the DCST data was re-analyzed by two readers 4 weeks after the initial review. RESULTS: All DSCT datasets were of diagnostic image quality concerning valve depiction. The mean AVA as measured by DSCT was 2.7+/-0.9 cm (2) compared to 1.8+/-0.5 cm (2) by echocardiography (p<0.05). The planimetric evaluation of the CT data as compared to results of echocardiography showed a significant correlation of the results (Pearson's correlation coefficient R=0.78, p<0.001). Intra- and inter-reader reproducibility was good with intra-class correlation coefficients of 0.86 and 0.81, respectively (p<0.001). There was a significant negative correlation between the amount of aortic valve calcification and AVA as measured by echocardiography (R= -0.42; p<0.05) and as measured by DSCT (R= -0.67; p=0.001). CONCLUSION: First experience indicates that DSCT is able to assess aortic valve opening area with high image quality and good intra- and inter-reader reproducibility in subjects after aortic valve replacement. The negative correlation between AVA and the amount of aortic valve calcification suggests that calcification is a possible risk factor for restenosis in subjects with aortic valve replacement.

Primary graft failure and Ca2+ sensitizers after heart transplantation.

Primary organ failure after heart transplantation is a severe complication generally related to prolonged ischemia time, poor quality of the organ, or rejection. Ca(2+) sensitisers increase cardiac contractility without altering intracellular Ca(2+) levels. Our aim was to evaluate the influence of levosimendan in the therapy of primary failure after heart transplantation. Five patients presenting with reduced ejection fraction (EF<30%) and high dosed catecholamines after heart transplantation were treated with levosimendan (Simdax, Abbot GesmbH, Vienna, Austria) in a 24-hour continuous infusion (0.10 microg/kg*min) postoperatively. We assessed hemodynamic measurements including MAP, CVP, and PAP as well as heart function. Pharmacologic support with catecholamines could be halved at 24 hours and terminated in four of the patients 72 hours after levosimendan administration. Hemodynamics (MAP 70 +/- 11 vs 85 +/- 6 mm Hg; CI 2.5 +/- 0.4 vs 3.6 +/- 0.4 L/min/m(2)) and EF (28 +/- 10 vs 54 +/- 4%) improved at 48 hours after treatment. Acute graft failure after cardiac transplantation is associated with poor short- and long-term outcomes. Among our patients, levosimendan reduced the need for catecholamine support as well as improved ventricular performance.

Successful reimplantation of a passive-fixation ventricle lead perforating the chest wall.

Delayed perforation of a passive fixed pacemaker lead is a rare complication after pacemaker implantation and is associated with increased morbidity and mortality. We report the case of an 82-year-old patient who presented with a delayed perforation of the right heart wall, the pericardium, and the chest wall by a passive-fixation ventricular lead 14 months after pacemaker implantation. The lead was uneventfully extracted transvenously and repositioned in the right ventricle with good pacing and sensing.

Fluvastatin as co-medication in heart transplant recipients with elevated creatine-kinase.

BACKGROUND: Statins reduce the risk for transplant vasculopathy and mortality among heart transplant recipients. Interactions between commonly used statins (ie, simvastatin, atorvastatin) and immunosuppressant drugs lead to side effects or withdrawal of statin therapy. Fluvastatin shows fewer interactions with the immunosuppressant agents because it is not metabolized via the cytochrome P-450 3A4 pathway like most immunosuppressants, steroids, or other statins. This study investigated the impact of a switch from other statins to fluvastatin in heart transplant recipients who revealed elevated creatine-kinase levels. METHODS: A total of 23 heart transplant patients with elevated creatine-kinase levels were included in this study. Statins were replaced with an equal dosage of fluvastatin. We measured on the day of replacement as well as there after at 3, 6, 9, and 12 months creatine-kinase, lipid status, ALT, AST, and creatinine levels. RESULTS: After 6 months creatine-kinase showed a significant reduction of 25% (P < .05) and after 9 months of 38% (P < .05). The HDL-cholesterol levels were significantly reduced at 6 months (8%; P < .05) and 9 months (23%; P < .05). At 3 months, triglyceride levels were significantly elevated (18%; P < .05). No differences were observed in ALT, AST, creatinine, total, and LDL-cholesterol at any time. CONCLUSION: A conversion from commonly used statins to fluvastatin in heart transplant patients with elevated creatine-kinase was safe, leading to a significant reduction in creatine-kinase levels. Except for an initial raise in triglycerides and a lowering of HDL-cholesterol, no changes in lipid status were seen. This conversion might help to maintain lipid-lowering therapy in transplant recipients who show side effects using conventional statins.

AAV-mediated gene transfer to cardiac cells in a heterotopic rat heart transplantation model.

INTRODUCTION: Adeno-associated virus (AAV) vectors offer the possibility to transfer genes to a wide range of organ and cell types. To determine the efficiency of AAV-mediated gene transfer to cardiac cells, vectors were administered to the heart under various conditions. METHODS: In Sprague-Dawley rats, AAV vectors based on serotype 2 and coding for beta-galactosidase were injected via coronaries into hypothermic nonbeating and normothermic beating hearts before transplantation. In addition, vectors were injected intravenously or into the thigh muscle. After 28 days all animals were humanely killed and organs explanted for analysis. RESULTS: Transgenic DNA was always detectable in the liver and the heart, irrespective of the application mode. However, transgenic mRNA could not be determined in the transplanted hearts. In contrast, direct injection into the thigh muscle resulted in transgenic mRNA production and marker gene expression. After systemic application, transgenic mRNA was detected in the liver but not in the heart. CONCLUSION: The results of our study indicated that AAV-mediated gene transfer to cardiac cells is possible. However, it was impossible to detect transgenic mRNA or marker gene expression in the transplanted hearts after intracoronary perfusion or systemic injection.

Transgenic animals in experimental xenotransplantation models: orthotopic heart transplantation in the pig-to-baboon model.

Pig organs are at risk for hyperacute and acute vascular rejection mediated by anti-pig antibodies, mainly binding to the Galalpha(1,3)Gal epitope. Acute cellular rejection is characterized by progressive infiltration of mononuclear cells. There is an ongoing search for immunosuppressive regimens that provide adequate protection against all patterns of xenograft rejection, but have no severe impact on the condition of xenograft recipients. Herein orthotopic heart transplantations were performed from hDAF or hCD46 piglets to nonsplenectomized baboons. Basic immunosuppression consisted of tacrolimus, sirolimus, GAS914, steroids, and ATG. Group 1 received basic immunosuppression. Group 2 was additionally treated with rituximab and group 3 with half-dose cyclophosphamide. Group 4 received cyclophosphamide and an anti-HLA-DR antibody. Three baboons received GAS914 and TPC. Monitoring included the regular assessment of anti-porcine antibodies, blood counts, therapeutic drug monitoring, and graft histology. Two grafts failed due to technical mistakes. In group 1, baboons died after 1 and 9 days. In group 2, maximum survival was 30 hours. In group 3, baboons lived 20 hours, 25 days, and 14 days. Group 4 survival times were 9.5 hours, 5.5 hours, 4 days, 34 hours, and 3 days. An increase of non-Galalpha(1,3)Gal antibodies was observed. Depositions of immunoglobulins and complement revealed a humoral rejection process. No cellular infiltration could be observed. In conclusion, suppressing cellular rejection with half-dose cyclophosphamide together with tacrolimus and sirolimus produced longer graft survival with a good general condition. Prevention of acute xenograft rejection further needs inhibition of non-Galalpha(1,3)Gal cytotoxicity by sufficient depression of B-cell activation.

Aberrant origin of the left main coronary artery arising from the right coronary artery associated with coronary artery disease: a case report.

Coronary artery anomalies are not frequent, nevertheless they are associated with increased and potentially lethal cardiac events. Recognition of these anomalies is fundamental in patients undergoing diagnostic or interventional coronary angiography. Most patients presenting with coronary anomalies are asymptomatic, but the risk of myocardial ischemia and sudden death requires the treatment of those patients. Different therapeutic options have been discussed, including surgery, conservative therapy, and interventional approaches. In this report, an aberrant origin of the left main coronary artery arising from the right coronary artery associated with coronary artery atherosclerosis and its surgical correction is described.

Successful single lung fontan operation in 2 children: case reports.

We report on 2 children, aged 3 and 4 years, with single ventricle physiology who underwent Fontan operation in the presence of a single right lung successfully with good midterm outcome. Therefore, the absence of one lung is not a contraindication for a Fontan palliation in selected patients with optimal hemodynamics.

Successful pulmonary thromboendarterectomy for right atrial thrombosis in a heart transplant recipient: a case report.

Acute massive or submassive pulmonary embolism is a life-threatening condition with a poor prognosis. It causes sudden hemodynamic deterioration and warrants immediate surgery. We report the case of a 41-year-old male heart transplant recipient who had not been treated prophylactically for thrombosis, who was referred to our center because of exertional dyspnea after immobilization owing to an injury in one of his legs. Transesophageal echocardiography revealed a large, mobile, right atrial mass originating from a pacemaker lead. Furthermore, contrast-enhanced computed tomography scanning of the chest revealed multiple pulmonary emboli resulting in subtotal occlusion of both pulmonary arteries. Although typically reserved for patients with chronic thromboembolic pulmonary hypertension, surgical thromboendarterectomy was successfully performed. Six months after discharge, the patient is well and has a New York Heart Association class 1 rating. This is the first report of a successful pulmonary thromboendarterectomy in a heart transplant recipient.

LEA29Y expression in transgenic neonatal porcine islet-like cluster promotes long-lasting xenograft survival in humanized mice without immunosuppressive therapy.

Genetically engineered pigs are a promising source for islet cell transplantation in type 1 diabetes, but the strong human anti-pig immune response prevents its successful clinical application. Here we studied the efficacy of neonatal porcine islet-like cell clusters (NPICCs) overexpressing LEA29Y, a high-affinity variant of the T cell co-stimulation inhibitor CTLA-4Ig, to engraft and restore normoglycemia after transplantation into streptozotocin-diabetic NOD-SCID IL2rγ-/- (NSG) mice stably reconstituted with a human immune system. Transplantation of INSLEA29Y expressing NPICCs resulted in development of normal glucose tolerance (70.4%) and long-term maintenance of normoglycemia without administration of immunosuppressive drugs. All animals transplanted with wild-type NPICCs remained diabetic. Immunohistological examinations revealed a strong peri- and intragraft infiltration of wild-type NPICCs with human CD45+ immune cells consisting of predominantly CD4+ and CD8+ lymphocytes and some CD68+ macrophages and FoxP3+ regulatory T cells. Significantly less infiltrating lymphocytes and only few macrophages were observed in animals transplanted with INSLEA29Y transgenic NPICCs. This is the first study providing evidence that beta cell-specific LEA29Y expression is effective for NPICC engraftment in the presence of a humanized immune system and it has a long-lasting protective effect on inhibition of human anti-pig xenoimmunity. Our findings may have important implications for the development of a low-toxic protocol for porcine islet transplantation in patients with type 1 diabetes.

Fluorescent microspheres reveal different regional blood flow in hyperacutely rejected nontransgenic and hDAF pig hearts.

Classic features of hyperacute rejection show differential severity in the inner compared to the outer myocardium. In the present study, regional blood flow (RBF) measured by fluorescent microspheres served as a marker of the extent of hyperacute rejection. Using a working heart model, hearts of nontransgenic and hDAF transgenic pigs were perfused with human blood. Additionally, hDAF transgenic pig hearts were perfused with human blood containing GAS914 or the GPIIb/IIIa inhibitor tirofiban. Injections of fluorescent microspheres into the donor heart were performed in situ and during perfusion. Reference arterial blood samples were collected from the inferior aorta and the afterload line. Perfusion was terminated before hyperacutely rejected hearts failed to pump against the afterload column. RBF was determined in tissue samples of standardized areas of the left atrium and ventricle. Each specimen was divided into subepicardial and subendocardial tissue samples. Fluorescence intensity was measured using an automated luminescence spectrometer. At the end of perfusion with human blood, hyperacutely rejected nontransgenic pig hearts showed a higher RBF in the subendocardium. In hDAF-transgenic pig hearts perfused with unmodified human blood the subendocardial/subepicardial blood flow ratio changed in favor of the subepicardium. This ratio was not further improved by GAS914. In contrast, tirofiban was able to assimilate subepicardial and subendocardial blood flow. In conclusion, RBF of hyperacutely rejected pig hearts was inhomogeneous. Inhibition of complement activation improved the reduced subepicardial RBF, but depletion of antibodies had no positive effect. The ability of tirofiban to further increase subepicardial RBF affirms thrombosis of subepicardial veins as the defining characteristic of hyperacute rejection.

Postoperative Heparin-Mediated Extracorporeal Low-Density Lipoprotein Fibrinogen Precipitation Aphaeresis Prevents Early Graft Occlusion after Coronary Artery Bypass Grafting.

Background Early graft occlusion due to thromboembolic events is a well-known complication after coronary artery bypass grafting (CABG). Fibrinogen, the coagulation factor I, is a glycoprotein that is transformed by thrombin into fibrin. It plays a major role in thrombus formation and is highly elevated after CABG. Our aim was to determine if postoperative lowering of fibrinogen levels by H.E.L.P. (heparin-mediated extracorporeal low-density lipoprotein [LDL] fibrinogen precipitation) aphaeresis could reduce the rate of early graft occlusion in patients with hypercholesterolemia undergoing CABG. Methods Between December 2004 and September 2009, 36 male patients with hypercholesterolemia (mean LDL cholesterol 128 ± 12 mg/dL), mean age 58 ± 9 years, underwent CABG. Mean preoperative fibrinogen level was 387 ± 17 mg/dL. H.E.L.P. aphaeresis was postoperatively performed when fibrinogen levels exceeded 350 mg/dL on day 1 and 250 mg/dL every consecutive day up to day 8. Pre- and postaphaeresis blood samples were obtained and plasma fibrinogen level reduction was calculated. Early graft occlusion was evaluated by means of coronary angiography or multislice computed tomography before discharge. Results A total of 128 distal anastomoses were performed in 36 patients (mean 3.6/patient). Postoperatively, 191 H.E.L.P. aphaeresis sessions were performed (mean 5.3/patient). Fibrinogen levels were lowered from 391 ± 10 mg/dL (preaphaeresis) to 171 ± 5 mg/dL (postaphaeresis; p < 0.001). Coronary angiography (multislice computed tomography in 7 patients) revealed graft patency in 125 of 128 grafts (98% patency) with three occluded venous grafts to target vessels of 1.5 mm. H.E.L.P. aphaeresis-related complications were limited to hypotensive episodes in two patients and bacteremia in one patient. Conclusions H.E.L.P. apheresis offers an easy, save, and efficient method to decrease fibrinogen postoperatively in patients having CABG. Showing excellent graft patency rates in comparison to the literature, this method is a promising tool to reduce early graft occlusion after CABG.