Camille Dambrin

Orthotopic aortic transplantation in mice: a new model of allograft arteriosclerosis

BACKGROUND Graft arteriosclerosis is a major cause of death after allotransplantation of organs such as the heart or the kidney. Aortic allotransplantation in mice is a useful experimental model to study the mechanisms of this pathology. However, the conventional heterotopic aortic model is limited by a high morbidity and is technically difficult to perform. We developed a new simple method for aortic transplantation in mice. METHODS The infrarenal aorta from the donor mouse was anastomosed to the recipients aorta at the same position using a sleeve technique. Orthotopic aortic transplantation was performed in 45 mice, 5 isografts and 40 allografts. No immunosuppression was given, and the mice were killed at day 15 or 30. The graft was examined macroscopically, and several histologic sections were made. RESULTS The overall survival rate was 78%. The incidence of thrombosis was low (4 cases) compared with previously published series. Histology of aortas revealed typical aspects of rejection in the allografts with a chronic picture at day 30. No significant lesion was observed in isografts. CONCLUSIONS We have developed a model of orthotopic aortic transplantation in mice. This new model is easy to carry out and has a low incidence of thrombosis, probably because there is no size discrepancy between donor and recipient aortic segment.

Sirolimus (Rapamycin) Monotherapy Prevents Graft Vascular Disease in Nonhuman Primate Recipients of Orthotopic Aortic Allografts

Background—Delayed treatment with sirolimus (SRL) halts progression of graft vascular disease (GVD) in nonhuman primate (NHP) aortic allograft recipients. In this study, we investigated whether SRL monotherapy prevents the development of GVD. Methods and Results—Pairs of 3-cm infrarenal aortic segments were exchanged between mixed lymphocyte reaction–mismatched, blood group–compatible NHPs (n=12). Six NHPs were untreated controls, and 6 were treated orally with SRL starting on the day of transplantation. Follow-up was 105 days. SRL doses were adjusted individually by assessing SRL blood concentrations, immune function, and clinical status. The severity of GVD was determined every 3 weeks by intravascular ultrasound, which quantified intimal area (IA) and intimal volume (IV) for the middle 1-cm graft segments. The mean±SEM SRL plasma levels were 14.5±9 ng/mL. In grafts from treated NHPs, IA and IV values on days 63, 84, and 105 were significantly lower than for controls (P <0.05 to P <0.001). On day 105, in the grafts from SRL-treated NHPs compared with grafts from controls, values (mean±SEM) were IA, 2.9±0.9 versus 5.5±0.7 mm2, P <0.001 and IV, 29.6±4.6 versus 55.2±2.8 mm3, P <0.001; IA and IV values for grafts from SRL-treated NHPs did not increase significantly between days 21 and 105. Conclusions—We show that SRL monotherapy prevented GVD in NHP aortic allograft recipients, suggesting the value of SRL for controlling GVD in clinical transplantation.

Effects of the malononitrilamide FK778 on immune functions in vitro in whole blood from non-human primates and healthy human volunteers.

BACKGROUND FK778, a malononitrilamide analog of leflunomide, is currently being investigated for use in clinical transplantation. METHODS Whole blood from cynomolgus monkeys (n=4) and healthy human volunteers (n=4) was incubated with different concentrations of FK778 and stimulated with mitogens in culture medium. Lymphocyte proliferation was assessed by tritium-labeled thymidine incorporation and by flow-cytometric analysis of expression of proliferating cell nuclear antigen on cells in S/G(2)M phase. Flow cytometry was also used to assess expression of T and B lymphocyte activation surface antigens and production of intracellular cytokines by T cells. RESULTS Not only lymphocyte proliferation, but also expression of various T cell surface antigens (CD25, CD11a, CD95, CD154) was suppressed by FK778. Fifty percent effective concentration values for the different immune functions were lower in human blood than in blood from cynomolgus monkeys. CONCLUSIONS FK778 inhibits multiple immune functions. Their flow cytometric evaluation can be used to assess the effects of the drug in vivo.

Treatment by Mycophenolate Mofetil of Advanced Graft Vascular Disease in Non‐Human Primate Recipients of Orthotopic Aortic Allografts

Failure to control chronic graft dysfunction [e.g. graft vascular disease (GVD)] is the primary cause of immunologic graft failure. This is the first study of mycophenolate mofetil (MMF) for the treatment of GVD in non‐human primate recipients of aortic allografts. Abdominal aortic allografts were exchanged between mixed leukocyte reaction (MLR) ‐mismatched, blood‐group‐compatible cynomolgus monkeys. Six control recipients were untreated. Individualized treatment with frequent dose adjustments of MMF insured that treatment was close to the maximum tolerated dose (mean 99.2 mg/kg/day). Immune‐mediated injury proceeded unhindered until day 45, after which MMF treatment began. Changes in intimal volume (IV) were quantified by intravascular ultrasound (IVUS) and compared to histology on day 105. Serial IVUS measurements of IV (mm3) in controls showed progressive GVD. In four out of six animals, MMF was well tolerated, thus enabling optimum treatment; in all these animals, IV was significantly less than in the control animals (p = 0.02). In the two remaining animals, high doses were not tolerated; at day 105, there was no significant difference in IV between them and the controls. We found a significant correlation between the mean MMF tolerated dose and the inhibition of progression of IV (r = −0.88, p = 0.015). When high MMF doses were tolerated, MMF slowed progression of GVD.

The Role of Stent-Grafts in the Management of Aortic Trauma

Stent graft has resulted in major advances in the treatment of trauma patients with blunt traumatic aortic injury (TAI) and has become the preferred method of treatment at many trauma centers. In this review, we provide an overview of the place of stent grafts for the management of this disease. As a whole, TEVAR repair of TAIs offers a survival advantage and reduction in major morbidity, including paraplegia, compared with open surgery. However, endovascular procedures in trauma require a sophisticated multidisciplinary and experienced team approach. More research and development of TAI-specific endograft devices is needed and large, multicenter studies will help to clarify the role of TEVAR compared with open repair of TAI.

Early prediction of 3-month survival of patients in refractory cardiogenic shock and cardiac arrest on extracorporeal life support

Background: Extracorporeal life support (ECLS) holds the promise of significant improvement of the survival of patient in refractory cardiogenic shock (CS) or cardiac arrest (CA). Nevertheless, it remains to be shown to which extent these highly invasive supportive techniques could improve long-term patients outcome. Methods: The outcomes of 82 adult ECLS patients at our institution between January 2012 and December 2013 were retrospectively analyzed. Results: Patients were essentially men (64.7%) and are 54 years old. Preexisting ischemic (53.7%) and dilated cardiomyopathy (14.6%) were frequent. ECLS indications were shared equally between CA and CS. ECLS-specific adverse effects as hemorrhage (30%) and infection (50%) were frequent. ECLS was effective for 43 patients (54%) with recovery for 35 (43%), 5 (6%) heart transplant, and 3 (4%) left ventricular assist device support. Mortality rate at 30 days was 59.8%, but long-term and 3-month survival rates were similar of 31.7%. Initial plasma lactate levels >5.3 mmol/L and glomerular filtration rate <43 ml/min/1.73 m2 were significantly associated with 3-month mortality (risk ratio [RR] 2.58 [1.21–5.48]; P = 0.014; RR 2.10 [1.1–4]; P = 0.024, respectively). Long-term follow-up had shown patients paucisymptomatic (64% New York Heart Association 1–2) and autonomic (activities of daily living [ADL] score 6 ± 1.5). Conclusion: In case of refractory CA or CS, lactates and renal function at ECLS initiation could serve as outcome predictor for risk stratification and ECLS indication.

Increased mean aliphatic lipid chain length in left ventricular hypertrophy secondary to arterial hypertension: A cross-sectional study.

AbstractAbout 77.9 million (1 in 4) American adults have high blood pressure. High blood pressure is the primary cause of left ventricular hypertrophy (LVH), which represents a strong predictor of future heart failure and cardiovascular mortality. Previous studies have shown an altered metabolic profile in hypertensive patients with LVH. The goal of this study was to identify blood metabolomic LVH biomarkers by 1H NMR to provide novel diagnostic tools for rapid LVH detection in populations of hypertensive individuals. This cross-sectional study included 48 hypertensive patients with LVH matched with 48 hypertensive patients with normal LV size, and 24 healthy controls. Two-dimensional targeted M-mode echocardiography was performed to measure left ventricular mass index. Partial least squares discriminant analysis was used for the multivariate analysis of the 1H NMR spectral data. From the 1H NMR-based metabolomic profiling, signals coming from methylene (–CH2–) and methyl (–CH3) moieties of aliphatic chains from plasma lipids were identified as discriminant variables. The –CH2–/–CH3 ratio, an indicator of the mean length of the aliphatic lipid chains, was significantly higher (P < 0.001) in the LVH group than in the hypertensive group without LVH and controls. Receiver operating characteristic curve showed that a cutoff of 2.34 provided a 52.08% sensitivity and 85.42% specificity for discriminating LVH (AUC = 0.703, P-value < 0.001). We propose the –CH2–/–CH3 ratio from plasma aliphatic lipid chains as a biomarker for the diagnosis of left ventricular remodeling in hypertension.

Structural evidence for a new elaborate 3D-organization of the cardiomyocyte lateral membrane in adult mammalian cardiac tissues

AIMS This study explored the lateral crest structures of adult cardiomyocytes (CMs) within healthy and diseased cardiac tissue. METHODS AND RESULTS Using high-resolution electron and atomic force microscopy, we performed an exhaustive quantitative analysis of the three-dimensional (3D) structure of the CM lateral surface in different cardiac compartments from various mammalian species (mouse, rat, cow, and human) and determined the technical pitfalls that limit its observation. Although crests were observed in nearly all CMs from all heart compartments in all species, we showed that their heights, dictated by the subsarcolemmal mitochondria number, substantially differ between compartments from one species to another and tightly correlate with the sarcomere length. Differences in crest heights also exist between species; for example, the similar cardiac compartments in cows and humans exhibit higher crests than rodents. Unexpectedly, we found that lateral surface crests establish tight junctional contacts with crests from neighbouring CMs. Consistently, super-resolution SIM or STED-based immunofluorescence imaging of the cardiac tissue revealed intermittent claudin-5-claudin-5 interactions in trans via their extracellular part and crossing the basement membrane. Finally, we found a loss of crest structures and crest-crest contacts in diseased human CMs and in an experimental mouse model of left ventricle barometric overload. CONCLUSION Overall, these results provide the first evidence for the existence of differential CM surface crests in the cardiac tissue as well as the existence of CM-CM direct physical contacts at their lateral face through crest-crest interactions. We propose a model in which this specific 3D organization of the CM lateral membrane ensures the myofibril/myofiber alignment and the overall cardiac tissue cohesion. A potential role in the control of sarcomere relaxation and of diastolic ventricular dysfunction is also discussed. Whether the loss of CM surface crests constitutes an initial and common event leading to the CM degeneration and the setting of heart failure will need further investigation.

Unusual Pathology in a Kidney from a Heart-Transplant Patient

Acute kidney injury (AKI) is often observed after heart transplantation. In this setting, acute tubular necrosis is the main histological finding on kidneys. We report the unusual pathology found in a kidney from a heart-transplant patient. The patient experienced several hemodynamic insults, massive transfusion, and implantation of a mechanical circulatory-support device before heart transplantation: there was prolonged AKI after transplantation. A kidney biopsy revealed acute tubular necrosis and renal hemosiderosis, which was probably related to the transfusion and to mechanical circulatory-support device-induced intravascular hemolysis. Assessment of iron during resuscitation could have prevented, at least partly, AKI.

0378: Mechanical circulatory support and factor VII: effective but (not so) dangerous?

Objectives Hemorrhagic complications are a main concern after mechanical circulatory support, alternative to heart transplantation, and often involve multiple transfusions and re-interventions at the initial phase. The Recombinant activated factor VII (NovoSeven®), expensive drug with proven blood savings in some coagulopathies, can help control mediastinal bleeding but runs the risk of pump thrombosis. Methods This is a single-center prospective cohort of patients wtih longterm electrical intracorporeal continuous flow left ventricular assist device (LVAD) type HeartMate II, between January 2008 and September 2014. We studied the post-operative use of blood products and their derivatives, especially NovoSeven®, and its consequences on the level of bleeding and thromboembolism. Results 42 devices were implanted in 36 men and 6 women with a mean age of 57.3 years, for 30 ischemic and 12 primitive cardiomyopathies, 10 cases in “Destination Therapy” and 32 in “Bridge-to-Transplantation”. The 30-day mortality was 6 patients, 1-year survival of 84%, the average intubation period of 7 days and ICU stay of 16.3 days. The average volume of thoracic drainage was 3036mL. The average transfusion per patient was 10.4 red blood cells, 7.1 fresh frozen plasma, 16.3 platelet units, 2.4g of fibrinogen (Clottafact®), 1162 IU of clotting factors (Octaplex®) and 2.9g of NovoSeven®. 17 patients (40.5%) received NovoSeven® (ranging from 4 to 15mg) including 8 during the procedure because of precarious hemostasis. Only 6 patients (14.3%) required reoperation for tamponade within J0 and J9, including 4 who had NovoSeven® prior. 6 patients (14.3%) had an intracardiac thrombus remote, 3 had received NovoSeven®. Conclusion An aggressive transfusion policy after LVAD can greatly limit the rate of surgical re-openings for bleeding, recognized as a risk factor for wound infection, without causing major thrombotic event.