In Vitro/Ex Vivo Models for the Study of Ischemia Reperfusion Injury during Kidney Perfusion.

Oxidative stress is a key element of ischemia-reperfusion injury, occurring during kidney preservation and transplantation. Current options for kidney graft preservation prior to transplantation are static cold storage (CS) and hypothermic machine perfusion (HMP), the latter demonstrating clear improvement of preservation quality, particularly for marginal donors, such as extended criteria donors (ECDs) and donation after circulatory death (DCDs). Nevertheless, complications still exist, fostering the need to improve kidney preservation. This review highlights the most promising avenues of in kidney perfusion improvement on two critical aspects: ex vivo and in vitro evaluation.

Benefit of Mineralocorticoid Receptor Antagonism in AKI: Role of Vascular Smooth Muscle Rac1.

AKI is a frequent complication in hospitalized patients. Unfortunately, there is no effective pharmacologic approach for treating or preventing AKI. In rodents, mineralocorticoid receptor (MR) antagonism prevents AKI induced by ischemia-reperfusion (IR). We investigated the specific role of vascular MR in mediating AKI induced by IR. We also assessed the protective effect of MR antagonism in IR-induced AKI in the Large White pig, a model of human AKI. In mice, MR deficiency in smooth muscle cells (SMCs) protected against kidney IR injury. MR blockade by the novel nonsteroidal MR antagonist, finerenone, or genetic deletion of MR in SMCs associated with weaker oxidative stress production. Moreover, ischemic kidneys had higher levels of Rac1-GTP, required for NADPH oxidase activation, than sham control kidneys, and genetic deletion of Rac1 in SMCs protected against AKI. Furthermore, genetic deletion of MR in SMCs blunted the production of Rac1-GTP after IR. Pharmacologic inhibition of MR also prevented AKI induced by IR in the Large White pig. Altogether, we show that MR antagonism, or deletion of the MR gene in SMCs, limited the renal injury induced by IR through effects on Rac1-mediated MR signaling. The benefits of MR antagonism in the pig provide a rational basis for future clinical trials assessing the benefits of this approach in patients with IR-mediated AKI.

Chirurgie aortique totalement laparoscopique ou par laparotomie: comparaison des résultats après appariement par un score de propension.

STUDY OBJECTIVE: To compare the postoperative and medium-term outcomes of laparoscopic aortic surgery with those of conventional aortic surgery performed by a surgical team trained in laparoscopic aortic surgery. METHODS: A prospective study was conducted between January 2006 and December 2011 with 228 consecutive patients having undergone aortic bypass surgery for either an abdominal aortic aneurysm (n = 139) or an occlusive aortoiliac disease (n = 89). Conventional open aortic surgery was carried out in 145 patients, and total laparoscopic repair in 83 patients. The composite primary endpoint measure grouped together the following adverse events (AE): (1) any details < 30 days or later deaths related to the operation, (2) postoperative hemorrhage necessitating reoperation, (3) myocardial infarction I 30 days. (4) stroke I 30 days, (5) postoperative respiratory failure necessitating reintubation or assisted ventilation J 4 days, (6) aortic prosthesis infection, (7) aortic prosthesis occlusion, (8) any reoperation related to aortic surgery. In order to diminish biases attributable to the absence of randomization, the two surgical groups were matched by a propensity score enabling analysis of 50 pairs of patients having presented with identical preoperative characteristics. Univariate analysis of the AE occurring during the first 30 postoperative days was followed by multivariate analysis through logistic regression. The incidence rate of AE during follow-up was calculated using the Kaplan-Meier method and the roles of the different covariables were analyzed using the Cox model. RESULTS: Univariate analysis of the groups adjusted for propensity score showed that laparoscopic repair was associated with significantly higher risk of AE over the first 30 postoperative days (p = 0.03). Logistic regression analysis showed that laparoscopic aortic technique (Odds Ratio (OR) ; 4.50) and coronary artery disease (OR ; 4.67) were independently related to occurrence of an AE during the postoperative period. Occurrence of AE during follow-up was analyzed using the Cox model. Only two variables, laparoscopic aortic surgery [Hazard Ratio (HR) ; 4,40 ; CI 95 % 1.70-11.38 ; p. = 0.002] and coronary artery occurrence of an AE during follow-up. The small number of patients prevented a separate analysis with regard to aneurysmal and occlusive aortic disease. CONCLUSIONS: This study suggests that even with a well-trained surgical team, the laparoscopic approach increases risk for AE observed in the course of aortic surgery. ClinicalTrials. gov Identifier: NCT02325700.

Toward Optimal Learning of the Gesture in Laparoscopic Surgery: Methodology and Performance.

Classical surgical education has to face both a forensic reality and a technical issue: to train a learner in more complex techniques in an increasingly short time. Moreover, surgical training is still based on an empirical hierarchical relationship in which learners must reproduce a sequence of actions in a situation of strong emotional pressure. However, the effectiveness of learning and its quality are linked to the emotional states in which learners find themselves. Among these emotions, epistemic confusion can be found that arises in complex learning situations where there is a cognitive imbalance related to the comprehension of the task, and which results from a rupture between the pre-established patterns of the learner and the new learning task. Although one knows that confusion can have a beneficial or a negative impact on learning, depending on whether it is well regulated or not, the factors that can influence it positively are still poorly understood. Thus, the objective of this experiment is to assess the impact of confusion on the learning of a surgical procedure in an augmented reality context and to determine if this impact varies according to the feedback given to the learners and according to the occurrence of disruptive events. Medical externs were recruited (N = 15) who were required to perform a suturing task on a simulator and whose performance was measured using a Motion Capture (MoCap) system. Even though the statistical analyzes did not allow a conclusion to be reached, the protocol already established makes it possible to consider a longer-term study that will allow (by increasing the number of sessions and the number of participants) more significant results to be obtained in order to develop new surgical learning protocols. This preliminary study opens a new field of research on the influence of epistemic emotions, and more particularly of confusion, which is likely to upset traditional surgical teaching, and is based on negative conditioning and strong emotions with negative valence as well as stress and coercion.

Trophic factor and FR167653 supplementation during cold storage rescue chronic renal injury.

PURPOSE: The use of organs from deceased after cardiac death and extended criteria donors grew in the last decade. These organs are more sensitive to ischemia-reperfusion injury during transplantation and current preservation protocols do not protect them adequately. MATERIALS AND METHODS: In an autotransplanted, deceased after cardiac death donor pig kidney model we evaluated the benefits of supplementation with University of Wisconsin solution trophic factors and FR167653, an inhibitor of p38 mitogen-activated protein kinase. RESULTS: Supplemented solution improved renal recovery and limited ischemia-reperfusion injury, particularly when agents were used in conjunction. Long-term benefits were highlighted by decreased renal fibrosis, as determined by Picrosirius staining, and inflammation, as evaluated by renal cell infiltration. Mechanistic evaluation showed decreased expression of epithelial-to-mesenchymal transition markers, a process involved in renal fibrosis development. Tumor necrosis factor-α was markedly decreased in the treated experimental group. Apoptosis was also decreased, accompanied by decreased p38 mitogen-activated protein kinase phosphorylation. CONCLUSIONS: Supplementing the current gold standard kidney preservation protocol with trophic factors and p38 mitogen-activated protein kinase inhibitors markedly increased the quality of grafts in our pig deceased after cardiac death donor model. Hence, this represents a strategy of interest to improve transplantation outcomes.

Total laparoscopic renal artery bypass for restenosis after failed percutaneous transluminal renal stenting.

OBJECTIVE: The purpose of this article was to report our experience of the repair of renal artery restenosis after percutaneous transluminal renal angioplasty (PTRA) using a total laparoscopic technique without robotic assistance. METHODS: Between February 2005 and October 2009, we performed six total laparoscopic aortorenal artery bypasses for restenosis after failed PTRA. All these patients had recurrent hypertension with renal insufficiency. RESULTS: The mean operative time was 246 minutes (range, 200-310 minutes). The mean warm renal ischemic time was 28 minutes (range, 22-35 minutes). All patients received a prosthetic graft interposition. The estimated surgical blood loss was 980 mL (range, 500-1400 mL). No conversion was observed and no in-hospital deaths occurred. There was no severe postoperative morbidity. Postoperative serum creatinine levels raised in all patients but all returned to baseline before discharge. Median length of postoperative hospital stay was 6 days (range, 4-8 days). Median follow-up was 13 months (range, 7-19 months). Color Doppler ultrasound scan examination and computed tomography (CT) with injection of contrast media showed patency of all bypasses. Hypertension was improved in all patients but renal insufficiency remained unchanged. CONCLUSION: Total laparoscopic renal artery bypass is feasible and safe in patients after failed PTRA. This approach may reduce the morbidity of open repair but is technically demanding and necessitates a large previous experience in total laparoscopic aortic surgery.

FR167653 improves renal recovery and decreases inflammation and fibrosis after renal ischemia reperfusion injury.

OBJECTIVE: Acute tubular necrosis (ATN) secondary to induced warm ischemia (WI) results in inflammatory and delayed fibrotic processes and remains a common clinical problem with serious consequences. Because tumor necrosis factor-alpha (TNF-alpha) is a prominent proinflammatory factor implicated in the pathophysiology of acute renal ischemia reperfusion injury (IRI), we hypothesized that FR167653 (FR), a potent inhibitor of TNF-alpha and interleukin-1beta production, may reduce IRI. METHODS: IRI was induced in male pigs by bilateral clamping of the renal pedicle for 90 minutes (WI90), or unilateral renal clamping (90 minutes) after contralateral nephrectomy (1/2Nx90), or unilateral renal clamping without contralateral nephrectomy (WIuni90). FR was administered intravenously 60 minutes before WI (1 mg/kg/h), during WI, and continuously for 3 hours (1 mg/kg/h) during reperfusion in treated groups (FRWI90, FR1/2Nx90, or FRWIuni90). Blood and urine samples were collected between day 1 and 3 months after reperfusion for assessment of renal function. Kidneys were excised and renal tissues were collected at 3 months for morphologic and inflammation evaluation and protein analysis. Experimental groups were compared with sham operated (control) and heminephrectomized (Unif) groups without renal ischemia. RESULTS: Three WI90 animals (43%) and five 1/2Nx90 (70%) were euthanized and necropsied at day 7 because of no urine production or poor conditions. Mortality was significantly improved after FR treatment. Survival was 100% in the control, Unif, WIuni90, and FR groups. In Unif groups, FR significantly reduced renal failure and bilateral renal ischemia (P < .05). At 3 months, proteinuria was significantly reduced in FR-treated groups (P < .01). Inflammatory cells count was also dramatically diminished in FR-treated pigs (P < .01 for CD3-positive cells). The second aspect of transient ischemia is the fibrotic process determined at 3 months. FR treatment was characterized by a reduction of renal fibrosis, particularly in Unif groups. TNF-alpha protein expression was diminished in FR-treated groups. CONCLUSION: This is the first evidence that FR reduced the early and long-term effect of WI in the severe ischemia model. This effect was particularly marked against fibrosis and inflammation, which would contribute to deterioration of a patient's renal function.

Laparoscopic aortic surgery: Techniques and results.

OBJECTIVE: This review describes and evaluates the results of laparoscopic aortic surgery. METHODS: We describe the different laparoscopic techniques used to treat aortic disease, including (1) total laparoscopic aortic surgery (TLS), (2) laparoscopy-assisted procedures including hand-assisted laparoscopic surgery (HALS), and (3) robot-assisted laparoscopic surgery, with their current indications. Results of these techniques are analyzed in a systematic review of the clinical series published between 1998 and 2008, each containing >10 patients with complete information concerning operative time, clamping time, conversion rate, length of hospital stay, morbidity, and mortality. RESULTS: We selected and reviewed 29 studies that included 1073 patients. Heterogeneity of the studies and selection of the patients made comparison with current open or endovascular surgery difficult. Median operative time varied widely in TLS, from 240 to 391 minutes. HALS had the shortest operating time. Median clamping time varied from 60 to 146 minutes in TLS and was shorter in HALS. Median hospital stay varied from 4 to 10 days regardless of the laparoscopic technique. The postoperative mortality rate was 2.1% (95% confidence interval, 1.4-3.0), with no significant difference between patients treated for occlusive disease or for aneurysmal disease. Conversion to open surgery was necessary in 8.1% of patients and was slightly higher with TLS than with laparoscopy-assisted techniques (P = .07). CONCLUSIONS: Analysis of these series shows that laparoscopic aortic surgery can be performed safely provided that patient selection is adjusted to the surgeon's experience and conversion is liberally performed. The future of this technique in comparison with endovascular surgery is still unknown, and it is now time for multicenter randomized trials to demonstrate the potential benefit of this type of surgery.

Influence of warm ischemia time on peripheral-type benzodiazepine receptor: a new aspect of the role of mitochondria.

The peripheral benzodiazepine receptor (PBR) is located mainly in the outer mitochondrial membrane and many functions are associated directly or indirectly with the PBR. We have studied the influence of different durations of warm ischemia (WI) on renal function, tissue damage and PBR expression in a Large Whitepig model. After a midline incision, the renal pedicle was clamped for 10 (WI10), 30 (WI30), 45 (WI45), 60 (WI60) or 90 min (WI90), and blood and renal tissue samples were collected between 1 day and 2 weeks after reperfusion for assessment of renal function. Metabolite excretion associated with renal ischemia reperfusion injury such as trimethylamine-N-oxide (TMAO) was quantified in blood by magnetic resonance spectroscopy. PBR mRNA and protein expression were determined in renal tissue. TMAO levels rose progressively and significantly with increasing duration of WI. PBR mRNA expression was upregulated between 3 h and 1 day after reperfusion in WI30, WI45 and WI60. Its upregulation was noted 3 days after reperfusion in WI90. At day 14, PBR transcript expression was not different from basal level in any group. PBR protein followed the same pattern. These findings suggest a new role for PBR which could be a major target in the regeneration process during ischemia reperfusion.

Modulation of peripheral-type benzodiazepine receptor during ischemia reperfusion injury in a pig kidney model: a new partner of leukemia inhibitory factor in tubular regeneration.

BACKGROUND: It was demonstrated that postischemic kidney expresses different factors in a pattern that recapitulates expression of these factors in the developing kidney. We investigated whether peripheral-type benzodiazepine receptor (PBR), which belongs to the mitochondrial permeability transition pore and is essential during development, could be influenced by the ischemia-reperfusion injury process when compared with leukemia inhibitor factor (LIF). STUDY DESIGN: PBR, LIF, and LIF receptor messengers and proteins were analyzed in adult normal and ischemic kidney under conditions mimicking cardiac arrest: 18 pigs were studied after 60 minutes of warm ischemia and reperfusion for 7 days and compared with sham-operated (Sham, n = 12) and control (CONT, n = 12) groups. The same messengers and proteins were assessed in fetal kidneys. RESULTS: In normal kidney, PBR was expressed in descending and ascending limbs of Henle and in distal tubules. After ischemia-reperfusion injury, PBR mRNA significantly increased between days 1 and 7 in cortex and outer medulla. PBR protein increased between days 1 and 7, and was transiently expressed in proximal tubules at days 1 and 3 and returned to basal level at day 7. LIF messenger and protein increased rapidly at day 1 in proximal tubules. In turn, LIF receptor messenger and protein were not changed during reperfusion. CONCLUSIONS: These results suggest that PBR may be implicated in ischemia-reperfusion injury and, particularly, in the regenerative process within proximal tubules with LIF. These new insights open the possibility of novel targets for organ protection and repair.

Inhibition of coagulation proteases Xa and IIa decreases ischemia-reperfusion injuries in a preclinical renal transplantation model.

Coagulation is an important pathway in the pathophysiology of ischemia-reperfusion injuries. In particular, deceased after circulatory death (DCD) donors undergo a no-flow period, a strong activator of coagulation. Hence, therapies influencing the coagulation cascade must be developed. We evaluated the effect of a new highly specific and effective anti-Xa/IIa molecule, with an integrated innovative antidote site (EP217609), in a porcine preclinical model mimicking injuries observed in DCD donor kidney transplantation. Kidneys were clamped for 60 minutes (warm ischemia), then flushed and preserved for 24 hours at 4°C in University of Wisconsin (UW) solution (supplemented or not). EP217609-supplemented UW solution (UW-EP), compared with unfractionated heparin-supplemented UW solution (UW-UFH) or UW alone (UW). A mechanistic investigation was conducted in vitro: addition of EP217609 to endothelial cells during hypoxia at 4°C in the UW solution inhibited thrombin generation during reoxygenation at 37°C in human plasma and reduced tumor necrosis factor alpha, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 messenger RNA cell expressions. In vivo, function recovery was markedly improved in the UW-EP group. Interestingly, levels of thrombin-antithrombin complexes (reflecting thrombin generation) were reduced 60 minutes after reperfusion in the UW-EP group. In addition, 3 months after transplantation, lower fibrosis, epithelial-mesenchymal transition, inflammation, and leukocyte infiltration were observed. Using this new dual anticoagulant, anti-Xa/IIa activity during kidney flush and preservation is protected by reducing thrombin generation at revascularization, improving early function recovery, and decreasing chronic lesions. Such an easy-to-deploy clinical strategy could improve marginal graft outcome.

Trimetazidine reduces early and long-term effects of experimental renal warm ischemia: a dose effect study.

OBJECTIVE: Renal ischemia reperfusion (IR) injury (IRI) is an important mechanism of acute renal failure (ARF) and a crucial factor of tissue damage during vascular surgery. IR may lead to tissue destruction and influence the early and long-term outcome of organs. The anti-anginal medication trimetazidine (TMZ) is a drug, the protective effects of which have been already assessed during cold preservation and warm ischemia (WI). The objective of this dose-effect study was to assess the role of TMZ in severe renal WI model. MATERIALS AND METHODS: We have used an established WI pig kidney model associated with a uninephrectomy condition and studied the dose-dependent role of TMZ (1, 5, and 10 mg/Kg, i.v. for 24 hours before WI) against deleterious effects of WI (60 minutes of WI followed by reperfusion) compared with sham-operated (control) and uninephrectomized animals (unif). Direct effect of TMZ was determined using different variables: renal function (creatinine clearance; C(cr)) and indirectly, the consequences on inflammation (cells infiltration), rate of apoptosis, fibrosis development, and renal epithelial cells change into myofibroblast, which defined epithelial to mesenchymal transition (alpha-smooth muscle actin [alpha-SMA] and vimentin expression). RESULTS: TMZ (5 or 10 mg/Kg) significantly increased C(cr) and reduced the inflammatory response prevalent in ischemic kidney injury and rate of apoptosis expression. In addition, the limitation of initial IRI was correlated with an earlier and greater expression of hypoxia-inducible transcription factor-1alpha (HIF-1alpha), which is a hypoxia marker during kidney regeneration. A reduction of the tubulointerstitial development of fibrosis and a limitation of the alpha-smooth muscle actin expression (alpha-SMA) was observed with TMZ treatment. At 3 months, vimentin expression was increased in WI groups without TMZ or low TMZ dose treatment compared with 5 or 10 mg/Kg treated groups. CONCLUSION: Collectively, these data suggest that TMZ made the warm ischemic kidneys more resistant to the deleterious impact of a single episode of IR and could have a role in preserving the ischemic kidney from long-term damage.

Stent-graft repair for thoracic aortic disease: results of an independent nationwide study in France from 1999 to 2001.

BACKGROUND: The purpose of this study was to assess the overall short-term outcome of stent-graft repair for thoracic aortic disease in France between June 1999 and May 2001. METHODS: This retrospective study was designed by the French National Health Insurance Fund for Salaried Workers. To ensure objectivity, data were retrieved at each center and checked by a team of medical advisors. RESULTS: Between June 1999 and May 2001, a total of 166 stent-graft repairs for thoracic aortic disease were performed in 166 patients, mainly by surgeons in the operating room (88%). Patients were classified according to the American Society of Anesthesiologists as status I or II in 24% of cases, status III in 56%, and status IV or V in 20%. The diameter of the thoracic aneurysm was less than 50 mm in 17% of cases. Seventeen patients (10%) died during the first 3 months, including 8 within the first 30 days after the procedure. A total of 49 complications were noted in 34 patients (20.5%). Endoleaks occurred in 27 patients (16.3%), including 8 that necessitated further treatment. Other stent-related complications included rupture (n = 3), aortoesophageal or tracheal fistula (n = 3), paraplegia (n = 6), stent migration (n = 2), visceral embolism (n = 5), and cerebral embolism (n = 2). There were 14 delivery-related complications (8%) at the catheterization site. Non-stent-related complications occurred in 14 (8%). CONCLUSIONS: This nationwide study demonstrates that stent-graft repair for thoracic aortic disease can be performed with acceptable postoperative morbidity. However, it is not a risk-free procedure and should continue to be used in an investigative setting.

Post-traumatic thoracic outlet syndromes.

This retrospective study aims to clarify the mechanisms, frequency, symptoms, treatment, and outcome of post-traumatic thoracic outlet syndromes. A total of 13 patients (7 men and 6 women) with a mean age of 41 +/- 16 years were studied. Underlying injuries resulted from sports, road, and household accidents. Bone lesions were pseudarthrosis, hypertrophic callus, and luxations. Congenital anomalies were observed in five patients (38%). Vascular lesions included aneurysm of the subclavian artery or vein, acute ischemia, and subclavian vein thrombosis. Operative treatment involving orthopedic and/or vascular surgery was indicated in all patients. Post-traumatic thoracic outlet syndrome occurs in young subjects after violent trauma. Vascular complications are frequent and severe. Treatment achieves good results but benefits may be diminished by bone or nerve involvement.

Totally laparoscopic aortic repair: a new device for direct transperitoneal approach.

On the basis of our experience with more than 71 cases of totally laparoscopic aortic surgery by the retrocolic approach, we have developed a new technique by a simple transperitoneal approach. The purpose of this report is to describe that technique and the novel laparoscopic bowel retractor used to ensure stable exposure of the aorta.