Start Of Perfusion Research Articles

Impact of Hypothermic Oxygenated Machine Perfusion on Immune Cell Clearance in Liver Transplantation: Enhancing Graft Function and Post-Transplant Outcomes.

Background: Hypothermic oxygenated machine perfusion (HOPE) has emerged as a critical innovation in liver transplantation (LTx), offering significant protection against ischemia-reperfusion injury (IRI). This study focuses on quantifying and characterizing immune cells flushed out during HOPE to explore its effects on graft function and post-transplant outcomes. Materials and Methods: Fifty liver grafts underwent end-ischemic HOPE. Perfusate samples were collected at three time points: at the start of perfusion, after 10 min, and at the end of perfusion. The samples were analyzed to quantify and characterize immune cells, assessing the effectiveness of HOPE in reducing cellular debris and its impact on graft quality. Results: The primary perfusate contained significant concentrations of immune cells, mainly segmented neutrophils, lymphocytes, and monocytes. After 10 min of perfusion, outflow cell concentration decreased by over 95%, and by the end of perfusion, a more than 99% reduction was observed. Conclusions: HOPE effectively reduces immune cell concentrations in liver grafts, suggesting a mechanism for improved graft function and reduced post-transplant complications. These findings support the continued use and optimization of HOPE in LTx.

Inflammatory Gene Expression in Livers Undergoing Ex Situ Normothermic Perfusion Is Attenuated by Leukocyte Removal From the Perfusate.

Ex situ normothermic perfusion (ESNP) is a method to evaluate and potentially recondition organs before transplantation. However, increased expression of inflammatory molecules, including by tissue-resident immune cells, may occur during the perfusion process, potentially negating the beneficial effects of perfusion. We used RNA sequencing to assess gene expression in 31 livers undergoing ESNP, including 23 donated after circulatory death (DCD) and 8 donated after brain death. In 7 DCD livers, a leucocyte filter was added to the circuit during perfusion. Biopsies were available for transcriptomic assessment in all cases at the start of perfusion and at varying time points postperfusion. During ESNP in DCD livers, we observed an increase in proinflammatory, profibrinolytic, and prorepair pathway genes. SERPINE1, encoding plasminogen activator inhibitor-1, was among the genes most significantly upregulated during perfusion in DCD livers, potentially promoting fibrin clot persistence in vasculature. We also found increased expression of monocyte and neutrophil recruiting chemokine and proinflammatory cytokine transcripts during ESNP, but several prorepair molecules, including thymic stromal lymphopoietin, were also upregulated. In both DCD and donation after brain death livers, interferon-gamma response genes were enriched, whereas oxidative phosphorylation genes decreased in organs with high perfusate alanine transaminase, a biomarker associated with adverse clinical outcomes. The inclusion of a leukocyte filter in the perfusion circuit mitigated the induction of inflammation/immune pathway genes during perfusion and was associated with enrichment in oxidative phosphorylation genes. Leukocyte removal during ESNP abrogates transcriptional changes that are associated with unfavorable clinical outcomes, potentially benefiting human livers undergoing ESNP.

In Vitro Evaluation of Adsorption Properties of Various Devices for Selective Lipopolysaccharide Hemoperfusion (Experimental Study)

The objective: to study in vitro adsorption properties of various devices for selective lipopolysaccharide (LPS) adsorption.Subjects and Methods: Various methods of closed circuit circulating bovine serum endotoxin solutions were used. The serum was perfused using an LPS sorption device for 240 min. Serum samples were collected before the start of perfusion, and 30, 60, 120, 150, and 240 minutes after the start of circulation. LPS concentrations were measured by the turbidimetric method. One column for polymyxin hemoperfusion and three devices for selective adsorption of lipopolysaccharides were assessed.Results: When using the device for polymyxin hemoperfusion, the concentration of endotoxin in bovine serum decreased by 61% during 120 minutes, and in 120 minutes after additional administration of endotoxin, it went down by 57%. When using the other three devices, these parameters made 9% and 6%, 10% and 8%, 5% and 10%, respectively. Conclusion. By definition, an in vitro study cannot provide for complex pathophysiological reactions occurring in the body during sepsis. Тhis fact leads to limitations in extrapolating the results obtained to clinical practice.

Optimal Conditions for Oxygenated Subnormothermic Machine Perfusion for Liver Grafts Using a Novel Perfusion Device

Liver transplantation from donors after cardiac death (DCD) resolves donor shortages. We investigated the optimal time for subnormothermic oxygenated perfusion in DCD liver transplantation. Ten F1 pigs (body weight: 27-32 kg) were allocated to 2 groups: the heart beating group (n=6), from which livers were retrieved while the heart was beating, and the donation after cardiac death (DCD) group (n=4), in which liver retrieval was performed on pigs under apnea-induced cardiac arrest for 20 minutes. In both groups, the livers were kept in cold storage for 2 hours after retrieval and perfused with a subnormothermic oxygenated Krebs-Henseleit buffer for 120 minutes. We used a novel perfusion device, which can set maximum perfusion pressures of arteries and portal vein, developed by Asahikawa Medical University and Chuo Seiko Co. Bile production, liver enzymes, and inflammatory cytokines were measured and the sinusoidal space, using tissue specimens taken from liver grafts, was measured at 30, 60, 90, and 120 minutes after the start of perfusion. Bile production peaked at 90 minutes. Significantly higher levels of liver enzymes and inflammatory cytokines were found in the DCD group (P < .05). The release of liver enzymes peaked at 60 minutes and that of inflammatory cytokines peaked at 90 minutes. The hepatic sinusoidal space was wide at 90 minutes and narrowed after 120 minutes. The results suggest that subnormothermic oxygenation perfusion may maintain optimal graft condition until around 90 minutes and perfusion for more than 120 minutes may be counterproductive.

Complex protocol of cardiopulmonary bypass

Complex protocol of cardiopulmonary bypass

New Pharmacokinetic Parameters of Imaging Substrates Quantified from Rat Liver Compartments.

Hepatobiliary imaging is increasingly used by pharmacologists to quantify liver concentrations of transporter-dependent drugs. However, liver imaging does not quantify concentrations in extracellular space, hepatocytes, and bile canaliculi. Our study compared the compartmental distribution of two hepatobiliary substrates gadobenate dimeglumine [BOPTA; 0.08 liver extraction ratio (ER)] and mebrofenin (MEB; 0.93 ER) in a model of perfused rat liver. A gamma counter placed over livers measured liver concentrations. Livers were preperfused with gadopentetate dimeglumine to measure extracellular concentrations. Concentrations coming from bile canaliculi and hepatocytes were calculated. Transporter activities were assessed by concentration ratios between compartments and pharmacokinetic parameters that describe the accumulation and decay profiles of hepatocyte concentrations. The high liver concentrations of MEB relied mainly on hepatocyte and bile canaliculi concentrations. In contrast, the three compartments contributed to the low liver concentrations obtained during BOPTA perfusion. Nonlinear regression analysis of substrate accumulation in hepatocytes revealed that cellular efflux is measurable ∼4 minutes after the start of perfusion. The hepatocyte-to-extracellular concentration ratio measured at this time point was much higher during MEB perfusion. BOPTA transport by multidrug resistance associated protein 2 induced an aquaporin-mediated water transport, whereas MEB transport did not. BOPTA clearance from hepatocytes to bile canaliculi was higher than MEB clearance. MEB did not efflux back to sinusoids, whereas BOPTA basolateral efflux contributed to the decrease in hepatocyte concentrations. In conclusion, our ex vivo model quantifies substrate compartmental distribution and transport across hepatocyte membranes and provides an additional understanding of substrate distribution in the liver. SIGNIFICANCE STATEMENT: When transporter-dependent drugs target hepatocytes, cellular concentrations are important to investigate. Low concentrations on cellular targets impair drug therapeutic effects, whereas excessive hepatocyte concentrations may induce cellular toxicity. With a gamma counter placed over rat perfused livers, we measured substrate concentrations in the extracellular space, hepatocytes, and bile canaliculi. Transport across hepatocyte membranes was calculated. The study provides an additional understanding of substrate distribution in the liver.

Inhibition of adamts13: a novel therapy to treat mechanical circulatory support-induced acquired von willebrand syndrome

Abstract Introduction Bleeding is the most frequent adverse event in patients with continuous flow mechanical circulatory support (CF-MCS) and has been linked to the occurrence of acquired von Willebrand syndrome (aVWS). MCS devices cause an increased shear-induced proteolysis of von Willebrand factor (VWF) by ADAMTS13, leading to aVWS. Hence, specifically blocking ADAMTS13 might be an efficient way to rescue the loss of HMW VWF multimers in CF-MCS patients. Purpose To investigate if blocking ADAMTS13, using an in-house developed inhibitory anti-ADAMTS13 monoclonal antibody (mAb), prevents the loss of high molecular weight (HMW) VWF multimers in in vitro CF-MCS systems and to determine the efficacy of this therapy in a CF-MCS calf model. Methods Human blood was perfused through in vitro CF-MCS systems (Heartmate II and Impella CP, axial flow heart pumps) in the presence of the inhibitory or control mAb (20 μg/mL). Bovine blood was perfused through an in vitro Impella 5.5 system with the inhibitory mAb (20 μg/mL) or PBS. Next, Impella 5.5 pumps were implanted in calves. One dose of the inhibitory mAb (600 μg/kg) or PBS was injected eight days after Impella implantation. Plasma samples were analysed for VWF multimers, VWF antigen (VWF:Ag) and VWF collagen binding activity (VWF:CB). Results A time-dependent decrease in HMW VWF multimers was observed in both in vitro CF-MCS systems in the presence of the control mAb, leading to a 70% reduction of HMW VWF multimers, 180 minutes (min) after blood perfusion (p=0.01 for HM II and p=0.0003 for Impella). This was also reflected by a severely decreased VWF:CB/VWF:Ag ratio (0.59±0.11 and 0.52±0.10 at 180 min versus 1.00±0.06 and 1.07±0.09 before perfusion, for the HM II (p=0.03) and Impella (p=0.001) respectively). Interestingly, blocking ADAMTS13 using the inhibitory mAb prevented the loss of HMW VWF multimers in both systems (p=0.50 for the HM II and p=0.06 for the Impella, 180 min after the start of perfusion). The preservation of HMW VWF multimers was also reflected by normal VWF:CB/VWF:Ag ratios (0.92±0.16 and 0.97±0.11 at 180 min versus 0.93±0.09 and 1.19±0.12 before perfusion for the HM II (p=0.75) and Impella (p=0.06) respectively). Blocking bovine ADAMTS13 using the inhibitory mAb could prevent the loss of HMW VWF multimers in the in vitro Impella 5.5 system, showing that the calf is a good preclinical animal model to study the in vivo effect of this novel therapy. Impella implantation in the calves led to a decrease in HMW VWF multimers (Figure 1A and B). Hence, this animal model represents the VWF laboratory features of MCS-induced aVWS. Moreover, the loss of HMW VWF multimers after pump implantation could be rescued after injection of the inhibitory mAb (Figure 1A and B). Conclusion Blocking ADAMTS13 rescues MCS-induced VWF proteolysis in calves. Hence, inhibiting ADAMTS13 function could become a promising therapeutic strategy to rescue aVWS-induced bleeding in MCS patients. Figure 1. Impella calf model Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Fund for Scientific Research Flanders

The Condition of the Rat Myocardium and Isolated Sheep Heart after Prolonged 24-Hour Hypothermic Preservation in a Pressurized Carbon Monoxide–Oxygen Gas Mixture

High organoprotective properties of a carbon monoxide (CO)–oxygen (O2) gas mixture were confirmed after prolonged (24-h) preservation of the papillary muscle and an isolated rat heart at 4°C. Hypothermic preservation in the high-pressure gas mixture (6 atm) provided efficient restoration of the contractile activity of the isolated rat heart after 24-h storage at 4°C. The isolated retrograde-perfused Langendorff heart performed physically relevant mechanical work, which was similar in duration to that of an intact control heart. Staining with triphenyltetrazolium chloride did not detect infarcted regions in the myocardium. After preservation, the heart tissue was highly capable of performing its function in a test for electrically stimulated contractile activity of papillary muscles. In the test group, The frequency–intensity relationship, the potentiation effect induced by a pause, and the response to stimulation with isoproterenol of test hearts generally corresponded to the parameters of a normal rat myocardium. A sheep heart, which is comparable in size and weight to a human heart, was for the first time successfully preserved using the gas mixture. Normal heartbeat was spontaneously restored after the start of perfusion in all experiments. Histology did not detect a significant difference between test and control sheep hearts. The normal tissue structure of the myocardium was preserved in the test hearts. The 24-h preservation achieved in the study was four times longer than the maximum allowable preservation time of standard static cold storage. The results obtained with the large laboratory animal heart model showed that the hypothermic preservation protocol is promising for prolonged storage of human hearts.

L-type Ca2+ channels' involvement in IFN-γ-induced signaling in rat ventricular cardiomyocytes.

The purpose of this study was to examine the effects of interferon-γ (IFN-γ) on calcium movement in rat ventricular myocytes. L-type Ca2+ currents (ICa,L) were recorded with the whole-cell configuration of the patch-clamp techniques. IFN-γ induces current density reduction at the test potential of 0mV by 47.6 ± 7.4%. Heparin, a selective inhibitor of inositol-1,4,5-triphosphate (IP3)-induced Ca2+ release, applied via a patch pipette, induced an ICa,L amplitude decrease of about 46 ± 5.6%. The addition of IFN-γ to heparin-treated cells has no effect on ICa,L. Ryanodine induced an ICa,L current amplitude decrease of 35.1 ± 6.2%. The addition of IFN-γ to ryanodine-treated cells caused an additional ICa,L inhibiting of 17.6 ± 4.8%. Both cyclopiazonic acid (CPA), a specific SERCA inhibitor, and a combination of CPA and ryanodine caused a significant reduction of the ICa,L amplitudes. Subsequent addition of IFN-γ inhibited ICa,L for an additional 16.3 ± 4.4%. The employment of chelerythrine in this study prevented IFN-γ-induced L-type Ca2+ channel inhibition in only 10min from the start of perfusion. Proposed mechanisms of regulation involved IFN-γ-induced IP3-sensitive Ca2+ release probably by a Ca2+-dependent translocation of PKC from the cytoplasm to the cell membrane as the obligatory first step of the IFN-γ-induced PKC-dependent L-type Ca2+ channel inhibition.

Optimum Perfusate Volume of Purified Subnormothermic Machine Perfusion for Porcine Liver Donated After Cardiac Death

IntroductionSubnormothermic machine perfusion (SNMP) shows some advantages for the preservation of grafts donated after cardiac death (DCD) and improvements in machine perfusion (MP) technology are important to enhance organ preservation outcomes for liver transplantation. In this study, we focused on purified subnormothermic machine perfusion (PSNMP) and volumes of perfusate removed to substitute for purification and replaced by modified University of Wisconsin-gluconate after the start of perfusion and investigated, in particular, the optimum perfusate purification volume. Several purification volumes under SNMP were compared. In addition, the perfusate purification during MP was indicated as a potential technique to enhance the organ quality of DCD grafts and extended-criteria donors. MethodsThe PSNMP at several volumes (0.5 L, 1.5 L, and 3 L) were compared with regular SNMP without any purification treatment (untreated control). In the PSNMP group, all perfusate was removed to substitute for purification of the perfusate by modified University of Wisconsin-gluconate solution after the start of perfusion. After removing the perfusate, new perfusate with the same components was perfused to preserve the porcine livers obtained under warm ischemia for 60 minutes using SNMP at 22°C porcine liver for 4 hours. ResultsThe concentrations of aspartate aminotransferase and lactate dehydrogenase in the untreated group were significantly higher during perfusion compared to those of the intervention group. There are no significant differences among the volume conditions of the purification groups. ConclusionsThe optimal volume of perfusate purification was confirmed with a simple experimental comparison between untreated and PSNMP conditions.

Experimental Machine Liver Perfusion Ex Vivo: First Russian Case-Report

Background/Objectives: The article describes preclinical trials of a new apparatus for normothermic machine perfusion of the donor liver that was designed and developed in the Central Research Institute of Robotics and Technical Cybernetics (Saint-Petersburg, Russia). Methods: An experimental study of a new apparatus for isolated perfusion of donor liver was performed on the isolated pig liver. Microcirculation parameters were controlled using computerized dopplerography ultrasound for blood flow studies MM-E-K. Findings: The device consists of the following components - two pumps for pumping fluids in two hydraulic circuits; container, wherein the sealed package is a liver transplant; pump control system; touch screen for setting input and output; uninterruptible power supply to provide mobile functions. Porcine liver was isolated, explanted and after 30 minutes of warm ischemia time it was placed into the apparatus from the pig after induced cardiac death. Liver was perfused with a perfusate of an original composition maintaining its viability. The developed apparatus maintained separate peristaltic blood flow in portal vein at 1.5 l/min and in common hepatic artery at 0.3 l/min, which corresponds to the physiological parameters. Perfusion using the developed apparatus for machine perfusion allowed restoring and preserving the functional state of the liver after 30 minutes of warm ischemia time, as evidenced by spontaneous recovery of the bile outflow, color and texture of the liver graft. Biochemical data values stabilize at physiological levels within 40 minutes after the start of perfusion. Applications/Improvements: The perfusion device is designed to restore and maintain the viability of the donor organ (liver) using extracorporeal flow normothermic perfusion of donor organs.

Sulodexide alone or in combination with low doses of everolimus inhibits the hypoxia-mediated epithelial to mesenchymal transition in human renal proximal tubular cells

Prolonged cold ischemia time, the period from the start of perfusion with cold preservation fluid after cessation of circulation due to arterial clamping until transplantation in the recipient, could induce epithelial-to-mesenchymal transition (EMT) in renal tubular cells, a process associated with chronic graft damage. In this context, everolimus (EVE) and sulodexide (SUL) could potentially slow down this process. To assess whether SUL (50 μg/ml), EVE (at 5, 10, 100 nM) or their combination were able to inhibit EMT in human renal epithelial proximal tubular cells (HK-2) reoxygenated after 24 h under hypoxic conditions, we used classical biomolecular strategies. Hypoxia induced upregulation of alpha smooth muscle actin (α-SMA), fibronectin (FN) and vimentin at gene-expression and α-SMA and FN at protein levels. However, the addition, after reoxygenation, of SUL plus low-dose EVE (5 nM) to the cell culture reversed this condition. Moreover, SUL and EVE were able to inhibit the hypoxia-induced Akt phosphorylation in HK2 cells and their morphological changes. Similarly, SUL was able to reverse the hyper-expression of EMT markers induced by high EVE dosage (100 nM) in cells cultured under both normoxic and hypoxic conditions. Our data reveal, for the first time, that sulodexide, alone or combined to low doses of everolimus, may hinder EMT in renal cells following hypoxia or minimize fibrotic complications due to high dosage of mammalian target of rapamycin inhibitors.

Adult heart transplantation with distant procurement and ex-vivo preservation of donor hearts after circulatory death: a case series

Orthotopic heart transplantation is the gold-standard long-term treatment for medically refractive end-stage heart failure. However, suitable cardiac donors are scarce. Although donation after circulatory death has been used for kidney, liver, and lung transplantation, it is not used for heart transplantation. We report a case series of heart transplantations from donors after circulatory death. The recipients were patients at St Vincent's Hospital, Sydney, Australia. They received Maastricht category III controlled hearts donated after circulatory death from people younger than 40 years and with a maximum warm ischaemic time of 30 min. We retrieved four hearts through initial myocardial protection with supplemented cardioplegia and transferred to an Organ Care System (Transmedics) for preservation, resuscitation, and transportation to the recipient hospital. Three recipients (two men, one woman; mean age 52 years) with low transpulmonary gradients (<8 mm Hg) and without previous cardiac surgery received the transplants. Donor heart warm ischaemic times were 28 min, 25 min, and 22 min, with ex-vivo Organ Care System perfusion times of 257 min, 260 min, and 245 min. Arteriovenous lactate values at the start of perfusion were 8·3-8·1 mmol/L for patient 1, 6·79-6·48 mmol/L for patient 2, and 7·6-7·4 mmol/L for patient 3. End of perfusion lactate values were 3·6-3·6 mmol/L, 2·8-2·3 mmol/L, and 2·69-2·54 mmol/L, respectively, showing favourable lactate uptake. Two patients needed temporary mechanical support. All three recipients had normal cardiac function within a week of transplantation and are making a good recovery at 176, 91, and 77 days after transplantation. Strict limitations on donor eligibility, optimised myocardial protection, and use of a portable ex-vivo organ perfusion platform can enable successful, distantly procured orthotopic transplantation of hearts donated after circulatory death. NHMRC, John T Reid Charitable Trust, EVOS Trust Fund, Harry Windsor Trust Fund.

Selective evaluation of high density lipoprotein from mouse small intestine by an in situ perfusion technique

The small intestine (SI) is the second-greatest source of HDL in mice. However, the selective evaluation of SI-derived HDL (SI-HDL) has been difficult because even the origin of HDL obtained in vivo from the intestinal lymph duct of anesthetized rodents is doubtful. To shed light on this question, we have developed a novel in situ perfusion technique using surgically isolated mouse SI, with which the possible filtration of plasma HDL into the SI lymph duct can be prevented. With the developed method, we studied the characteristics of and mechanism for the production and regulation of SI-HDL. Nascent HDL particles were detected in SI lymph perfusates in WT mice, but not in ABCA1 KO mice. SI-HDL had a high protein content and was smaller than plasma HDL. SI-HDL was rich in TG and apo AIV compared with HDL in liver perfusates. SI-HDL was increased by high-fat diets and reduced in apo E KO mice. In conclusion, with our in situ perfusion model that enables the selective evaluation of SI-HDL, we demonstrated that ABCA1 plays an important role in intestinal HDL production, and SI-HDL is small, dense, rich in apo AIV, and regulated by nutritional and genetic factors.

Effects of Pharyngeal Cooling on Brain Temperature in Primates and Humans

Pharyngeal cooling decreases brain temperature by cooling carotid arteries. This study was designed to evaluate the principle of pharyngeal cooling in monkeys and humans. Monkeys (n = 10) were resuscitated following 12 min of cardiac arrest. Pharyngeal cooling (n = 5), in which cold saline (5°C) was perfused into the cuff at the rate of 500 ml/min, was initiated simultaneously with the onset of resuscitation for 30 min. Patients (n = 3) who were in an intensive care unit were subjected to 30 min of pharyngeal cooling under propofol anesthesia. In the animal study, core brain temperature was significantly decreased compared with that in the control group by 1.9°C (SD = 0.8, P < 0.001) and 3.1°C (SD = 1.0, P < 0.001) at 10 min and 30 min after the onset of cooling, respectively. The cooling effect was more evident in an animal with low postresuscitation blood pressure. Total dose of epinephrine, number of direct current shocks, and recovery of blood pressure were not different between the two groups. The pharyngeal epithelium was microscopically intact on day 5. In the clinical study, insertion of the cuff and start of perfusion did not affect heart rate or blood pressure. Tympanic temperature was decreased by 0.6 ± 0.1°C/30 min without affecting bladder temperature. The pharynx was macroscopically intact for 3 days. Pharyngeal cooling rapidly and selectively decreased brain temperature in primates and tympanic temperature in humans and did not have adverse effects on return of spontaneous circulation, even when initiated during cardiac arrest in primates.

Gene expression in human small intestinal mucosa in vivo is mediated by iron-induced oxidative stress

Iron-induced oxidative stress in the small intestine may alter gene expression in the intestinal mucosa. The present study aimed to determine which genes are mediated by an iron-induced oxidative challenge in the human small intestine. Eight healthy volunteers [22 yr(SD2)] were tested on two separate occasions in a randomized crossover design. After duodenal tissue sampling by gastroduodenoscopy, a perfusion catheter was inserted orogastrically to perfuse a 40-cm segment of the proximal small intestine with saline and, subsequently, with either 80 or 400 mg of iron as ferrous gluconate. After the intestinal perfusion, a second duodenal tissue sample was obtained. Thiobarbituric acid-reactive substances, an indicator of lipid peroxidation, in intestinal fluid samples increased significantly and dose dependently at 30 min after the start of perfusion with 80 or 400 mg of iron, respectively (P < 0.001). During the perfusion with 400 mg of iron, the increase in thiobarbituric acid-reactive substances was accompanied by a significant, momentary rise in trolox equivalent antioxidant capacity, an indicator of total antioxidant capacity (P < 0.05). The expression of 89 gene reporters was significantly altered by both iron interventions. Functional mapping showed that both iron dosages mediated six distinct processes. Three of those processes involved G-protein receptor coupled pathways. The other processes were associated with cell cycle, complement activation, and calcium channels. Iron administration in the small intestine induced dose-dependent lipid peroxidation and a momentary antioxidant response in the lumen, mediated the expression of at least 89 individual gene reporters, and affected at least six biological processes.

Isoflurane and sevoflurane during reperfusion prevent recovery from ischaemia in mitochondrial KATP channel blocker pretreated hearts

Inhalation anaesthetics given only during post-ischaemic reperfusion have some protective effect against reperfusion injury in the heart. Adenosine triphosphate-regulated mitochondrial potassium channels have been shown to be an important mediator of cardioprotection. Thus, we investigated whether 5-hydroxydecanoate, a putative mitochondrial potassium channel blocker, prevents the cardioprotective effect of volatile anaesthetics. Forty rats were randomly allocated to four groups of equal size: control group, 5-hydroxydecanoate group, 5-hydroxydecanoate + sevoflurane group and 5-hydroxydecanoate + isoflurane group. Seven minutes after the start of perfusion, normal saline (control group) or 5-hydroxydecanoate (the other groups) was administered. Ten minutes after the start of perfusion, the heart was rendered globally ischaemic for 10 min. One minute before the end of the ischaemic period, 2.7% sevoflurane or 1.4% isoflurane were administered in the 5-hydroxydecanoate + sevoflurane or 5-hydroxydecanoate + isoflurane groups respectively. The heart was reperfused for 10 min. Adenosine triphosphate content at the end of reperfusion in the 5-hydroxydecanoate + sevoflurane group was significantly lower (P < 0.05) than those in the control and the 5-hydroxydecanoate + isoflurane groups (19.9 +/- 8.7, 28.1 +/- 3.4 and 30.4 +/- 2.3 micromol g(-1), respectively). In addition, the combination of inhalation anaesthetics and 5-hydroxydecanoate decreased the ratios of recovered hearts from ischaemia (5-hydroxydecanoate + sevoflurane group: 40%, 5-hydroxydecanoate + isoflurane group 50%). 5-hydroxydecanoate alone caused no significant changes in haemodynamics and myocardial metabolism. However, the combination of 5-hydroxydecanoate and volatile anaesthetics impaired the recovery from ischaemia. Although animal data cannot be extrapolated to human beings, we suggest that more attention be paid to patients on sulphonylurea drugs, which inhibit potassium channels, when they are anaesthetized with volatile anaesthetics.

Isolated hyperthermic liver perfusion with cytostatic-containing perfusate activates the complement cascade.

Eight patients with advanced liver malignancy undergoing isolated hyperthermic liver perfusion with melphalan and cisplatin were studied with regard to complement activation and formation of anaphylatoxins (C3a and C5a) and terminal C5b-9 complement complexes (TCCs). Blood samples for complement variables (C1-INH, C3, C4, C5, C3a, C5a and TCCs) were taken before surgery, 1 min before the start of perfusion, 1, 2 and 3 h after the start of perfusion, and 24 h after operation. Samples were drawn from the perfusate 1 h after the start of perfusion. Activation of complement was observed during perfusion. Raised plasma concentrations of C3a and TCCs were recorded and high levels of C3a and TCCs were found in the perfusate. In vitro tests indicated that melphalan and cisplatin may activate complement. This activation occurred at 37 and 42 degrees C but was more pronounced at 42 degrees C.

An in situ perfusion protocol of rat epididymal adipose tissue useful in metabolic studies

Experimental approaches involving the perfusion of tissues and organs offer the advantage of improved physiological relevance over the use of isolated tissues or cells while at the same time being much more controlled and tissue-specific than studies in vivo. Nevertheless, there have been few metabolic studies performed in perfused white adipose tissue, largely because of the difficulty of the surgical technique involved. Although some methods have been described, they are difficult to use as perfusion protocols and their reproducibility is poor. We have modified a rat perfusion method, based on a modification of the Ho and Meng technique, for use with epididymal white adipose tissue (eWAT), and we present it here as a protocol to be reproduced. We also offer surgical solutions for the most common variants of vessel distributions in rats. Using the protocol described here, the perfused adipose tissue is viable and metabolically active, as indicated by the maintenance of tissue ATP levels and adiponectin secretion and by endogenous lipolysis regulation. Moreover, there is a high level of lipoprotein lipase activity in the endothelium of the tissue, which is heparin-releasable. Thus, this method is a useful and reproducible tool that allows the perfusion of eWAT for use in metabolic studies.

Near-infrared spectroscopic assessment of mitochondrial oxygenation status—comparison during normothermic extracorporeal liver perfusion by buffer only or buffer fortified with washed red blood cells: an experimental study

Background Use of marginal and non–heart-beating donors leads to an increased incidence of complications after clinical liver transplantation. Normothermic extracorporeal liver perfusion (NELP) may allow resuscitation and evaluation of such organs. Despite recent success in long-term liver preservation by NELP, no methods of organ evaluation have been defined. Mitochondrial cytochrome oxidase (Cyt Ox) levels reflect oxygen and substrate delivery, and hence ATP production at the cellular level. This study used near-infrared spectroscopy (NIRS) to measure Cyt Ox levels during NELP. Methods Livers retrieved from New Zealand white rabbits were immediately perfused in an extracorporeal circuit with oxygenated buffer (group A, n = 4) or red blood cell (RBC)–fortified buffer (group B, n = 4). Perfusion was continued for 3 hours at 37°C pH 7.4, and perfusate was gassed with 95%O 2/5%CO 2 at 1 liter per minute. Cyt Ox levels were monitored continuously by NIRS and bile output was measured. Results Cyt Ox was reduced at the start of perfusion in both groups, but even more rapidly in the buffer-perfused group. After initial deterioration, Cyt Ox levels improved significantly ( P < .05) with perfusion in the RBG-perfused group, but remained impaired in the buffer group 5.74 ± 1.51 Δμmol/L and −25.77 ± 21.94 Δμmol/L for groups B and A, respectively, at 180 minutes. Differences in bile output were not significant (19.33 ± 9.50 and 25.00 ± 16.81 μmol/min/100 g for groups B and A respectively). Conclusions Cyt Ox levels may offer better viability markers than bile output. NIRS is a practical method to measure tissue oxygenation, and RBC-based perfusion provided better oxygenation during NELP.