Low-potassium Dextran Glucose Solution Research Articles

Thyroid hormone protects human lung epithelial cells from cold preservation and warm reperfusion-induced injury

BackgroundCellular stress associated with static-cold storage (SCS) and warm reperfusion of donor lungs can contribute to ischemia–reperfusion (IR) injury during transplantation. Adding cytoprotective agents to the preservation solution may be conducive to reducing graft deterioration and improving post-transplant outcomes.MethodsSCS and warm reperfusion were simulated in human lung epithelial cells (BEAS-2B) by exposing cells to low potassium dextran glucose solution at 4 °C for different periods and then switching back to serum-containing culture medium at 37 °C. Transcriptomic analysis was used to explore potential cytoprotective agents. Based on its results, cell viability, caspase activity, cell morphology, mitochondrial function, and inflammatory gene expression were examined under simulated IR conditions with or without thyroid hormones (THs).ResultsAfter 18 h SCS followed by 2 h warm reperfusion, genes related to inflammation and cell death were upregulated, and genes related to protein synthesis and metabolism were downregulated in BEAS-2B cells, which closely mirrored gene profiles found in thyroid glands of mice with congenital hypothyroidism. The addition of THs (T3 or T4) to the preservation solution increases cell viability, inhibits activation of caspase 3, 8 and 9, preserves cell morphology, enhances mitochondrial membrane potential, reduces mitochondrial superoxide production, and suppresses inflammatory gene expression.ConclusionAdding THs to lung preservation solutions may protect lung cells during SCS by promoting mitochondrial function, reducing apoptosis, and inhibiting pro-inflammatory pathways. Further in vivo testing is warranted to determine the potential clinical application of adding THs as therapeutics in lung preservation solutions.

Using nutrient-rich solutions and adding multiple cytoprotective agents as new strategies to develop lung preservation solutions.

Commonly, donor lungs are preserved with low-potassium dextran glucose solution at low temperature. We hypothesized that adding nutrients and/or cytoprotective agents to preservation solutions improves donor lung quality. Human lung epithelial cells and human pulmonary microvascular endothelial cells cultured at 37°C with serum containing medium were switched to designated testing solutions at 4°C with 50% O2 for different cold ischemic time, followed by switching back to serum containing culture medium at 37°C to simulate reperfusion. We found that bicarbonate buffer system should be avoided in preservation solution. When pH was maintained at physiological levels, cell culture media showed better cell survival than in low-potassium dextran glucose solution. Phosphate-buffered cell culture media were further improved by adding colloid dextran 40. When rat donor lungs were preserved at 4°C for 24 h, phosphate-buffered Roswell Park Memorial Institute-1640 medium [RPMI-1640(p)] plus dextran 40 or adding cytoprotective agents (alpha 1 antitrypsin, raffinose, and glutathione) to low-potassium dextran glucose solution prevented alveolar wall swelling, apoptosis, activation of endothelial cells, and cellular edema. Using nutrient-rich solution and/or adding multiple cytoprotective agents is a new direction for designing and developing organ preservation solutions. Cell culture model, as a screening tool, reduces the use of animals and provides potential underlying mechanisms.

Mesenchymal stem cells attenuate ischemia-reperfusion injury after prolonged cold ischemia in a mouse model of lung transplantation: a preliminary study.

Mesenchymal stem cells (MSCs) suppress inflammation and immune responses. We conducted this study to find out if MSCs attenuate ischemia-reperfusion injury in a mouse model of lung transplantation. C57BL/6J mouse lungs perfused with low-potassium dextran glucose solution were preserved at 4°C for 18h. Human MSCs were slowly injected into the left pulmonary artery of the lung grafts, and orthotopic left lung transplantation was then performed. The lung isografts were reperfused for 6h, and bronchoalveolar lavage fluid (BALF) from the left lung graft was collected. We measured the protein concentration, cell count, and proinflammatory cytokine concentrations in the BALF. The protein concentration and cell count in the BALF were significantly lower in the MSC-administered grafts than in the PBS-administered controls. Concentrations of proinflammatory cytokines, including IL-1β, IL-17A, and TNF-α, in BALF tended to be lower in the MSC-administered grafts than in the controls, but the difference was not significant. The pre-transplant administration of MSCs via the pulmonary artery of the lung graft attenuated ischemia-reperfusion injury after prolonged cold ischemia in this mouse model of lung transplantation.

(467) - Polymerized Human Serum Albumin as an Osmotic Molecule to Support Ex-Vivo Lung Perfusion

Ex vivo lung perfusion (EVLP) is an integral method of organ preservation that could expand the donor pool by allowing organ assessment and recovery before transplantation. The composition of the perfusion solution is crucial in maintaining and improving the function of the organ during EVLP. This study was performed to compare the outcomes of EVLP using perfusate supplemented with polymeric human serum albumin (polyHSA) versus human serum albumin (HSA) using a small animal model. Rat heart-lung blocks were procured, cold flushed with low potassium dextran glucose solution, and divided into two treatment groups: normothermic EVLP using modified cell culture media supplemented with either 4% HSA or 4% polyHSA (n=6, each). The deoxygenated solution (6% O2, 8%CO2, 86% N2) was at 20% cardiac output for 120 minutes at 37oC. The lungs were evaluated using oxygen production, lung compliance, pulmonary vascular resistance (PVR), wet-to dry ratio and lung weight. Standard statistical methods were used. PolyHSA concentrations were formulated and perfused in comparison to weight by volume protein concentration. At 2 hours of normothermic EVLP the type of perfusion solution (HSA or polyHSA) significantly impacted the end organ metrics. Oxygen production, lung compliance, and PVR were comparable between the cohorts (p>0.05) at 2 hours of EVLP. The HSA group showed a significant increase in lung weight and wet to dry ration, when compared to the polyHSA cohort (both p< 0.05, figure). In a small animal model of normothermic EVLP a polyHSA-supplemented perfusate demonstrated significantly less edema, as compared to HSA. The solution oncotic pressure and physical properties of the molecule can have a direct impact on tissue edema and lung weight that develops with EVLP. This observation demonstrates the importance of refining preservation / perfusion solutions and the need to optimize the perfusate used in EVLP with use of polyHSA to limit pulmonary edema.

Mesenchymal Stem Cells Attenuates Ischemia Reperfusion Injury after Orthotopic Lung Transplantation in a Mouse Model

Purpose Mesenchymal stem cells (MSCs), multipotent mesenchymal stromal cells, have been shown to possess immunomodulatory and antiinflammatory properties. We hypothesized that MSCs may attenuate ischemia reperfusion injury after lung transplantation in mice. Methods and Materials C57BL/6 lungs were stored for 18 hours in low-potassium dextran glucose solution at 4°C prior to transplantation. The left lung grafts were orthotopically transplanted into C57BL/6 mice. A frozen vial of human MSCs (isolated from healthy male, courtesy of Dr. Darwin Prockop, Texas AM 1.095 vs 1.965 mg/ml, p=0.037, cell count; 0.61x10^5 vs 1.09x10^5 cells, p=0.011). IL-1β, IL17A and TNFα levels in BALF showed a trend toward a decrease in MSCs administered mice compared with PBS administered mice (IL-1β; 26.6 vs 38.7 pg/ml, p=0.13, IL17A; 284 vs 655 pg/ml, p=0.097, TNFα; 234 vs 500 pg/ml, p=0.073). Human MSCs were found in the lung graft 6 hours after lung transplantation by immunohistochemistry against human HLA class I. Conclusions MSCs attenuated ischemia reperfusion injury, which was accompanied by a trend toward decreased levels of proinflammatory cytokines in the graft after lung transplantation in a mouse model.

Basal segmental auto-transplantation after pneumonectomy for advanced central lung cancer

In patients with central lung cancer that extensively involves the bronchus/pulmonary artery, a double-sleeve lobectomy is often difficult to perform. We describe a case of post-pneumonectomy basal segmental auto-transplantation using a lung preservation technique that uses cold low-potassium dextran glucose solution to protect the lung graft from ischaemia-reperfusion injury during the ex situ division of the segmental graft and the pathological investigations for the clearance of the surgical margins. A right basal segmental auto-transplantation procedure was performed in a patient with stage-IIIA squamous cell lung cancer. This technique could allow extensive pulmonary resection while minimizing the loss of pulmonary reserve.

Addition of a neutrophil elastase inhibitor to the organ flushing solution decreases lung reperfusion injury in rat lung transplantation

Neutrophil elastase plays an important role in ischemia-reperfusion injury. We hypothesized that the addition of sivelestat, a specific neutrophil elastase inhibitor, to the organ flushing solution would decrease reperfusion injury in a rat single left-lung transplant model. All donor lungs were flushed with 25 ml low-potassium dextran-glucose solution and stored for 16 h at 4 degrees C. Rats were divided into three experimental groups (n=10) that received donor lungs washed in either normal flushing solution (group 1), or flushing solution containing 20mg sivelestat (group 2) or 40 mg sivelestat (group 3). Graft function was assessed 48 h after reperfusion using five measurements: isolated graft oxygenation, wet/dry ratio, peak airway pressure, tissue myeloperoxidase activity, and serum lipid peroxides level. Histological examination of lung grafts was also performed. Group 3 showed better oxygenation (groups 1, 2, and 3: 133.9+/-113.5, 254.0+/-84.6, and 378.7+/-77.6 mmHg, respectively; p<0.0001 vs group 1, p=0.0052 vs group 2), lower peak airway pressure (groups 1, 2, and 3: 28.7+/-6.1, 26.0+/-5.8, and 21.5+/-5.3 mmHg, respectively; p=0.0385 vs group 1), lower wet/dry ratio (groups 1, 2, and 3: 6.74+/-0.78, 5.77+/-0.52, and 4.90+/-0.16, respectively; p=0.0010 vs group 1), and lower myeloperoxidase activity (groups 1, 2, and 3: 0.304+/-0.081, 0.178+/-0.053, and 0.106+/-0.029 DeltaOD/mg/min, respectively; p<0.0001 vs group 1, p=0.0319 vs group 2). No significant differences in arterial PaCO(2) and serum lipid peroxide levels were observed between the three groups. Addition of sivelestat to the organ flushing solution ameliorated ischemia-reperfusion injury in a lung transplant model.

Canine Bilateral Lung Transplantation After 18-hour Preservation Using Non–heart-beating Donors

We previously reported that lung inflation with oxygen, EPC-K1 (a diester alpha-tocopherol and ascorbic acid), urokinase and low-potassium dextran glucose (LPDG) solution can be beneficial in lung preservation. In the present study, a canine bilateral lung transplantation (BLT) model was used to evaluate long-term lung preservation of non-heart-beating donors (NHBDs). Animals were euthanized without heparinization and left at room temperature for 2 hours until lung extraction. After cardiac arrest, the lungs were kept inflated with 100% oxygen. After extraction, the donor lungs were flushed with LPDG solution containing EPC-K1 (1.0 mg/liter), followed by injection of urokinase (120,000 IU) into the pulmonary artery. Eighteen BLTs were performed after preservation at 4 degrees C. Total ischemic time was scheduled for 12 hours in Group 1 (n = 6), 18 hours in Group 2 (n = 6) and 24 hours in Group 3 (n = 6). After BLT, recipients were followed up for 6 hours. An additional 6 BLTs were performed as a chronic study in the same setting as for Group 2. All animals in Groups 1 and 2 showed excellent pulmonary function during the 6-hour post-transplant assessment time, in contrast to only 2 dogs from Group 3. In the chronic study, all 6 animals showed excellent pulmonary function for 24 hours (PaO2 = 528 +/- 8 mm Hg with 100% oxygen) and 2 of them survived for >1 week. Successful chronic lung preservation (18 hours) using NHBDs is achievable in a canine BLT model.

Beneficial Effects of Supplemental Nitric Oxide Donor Given during Reperfusion Period in Reperfusion-Induced Lung Injury

Reperfusion injury is a perplexing cause of early graft failure after lung transplantation and today we know that reperfusion may be more harmful to tissues than the preceding ischemia. We hypothesized that administration of the nitric oxide donor nitroglycerin (NTG) during flush perfusion and reperfusion periods would ameliorate reperfusion-induced lung injury. Using an IN SITU normothermic ischemic lung rabbit model, three groups were studied (n = 7/group): (1) NTG given during flush perfusion (ischemia group); (2) NTG given in the flush perfusion and the reperfusion period (reperfusion group); and (3) no NTG (control group). All groups were flushed with low potassium dextran glucose solution. Blood gas analysis, tissue nitrite (nitric oxide metabolite) level analysis, bronchoalveolar lavage (BAL) fluid examination and morphological examinations were performed. Compared with the ischemia group, the reperfusion group had significantly improved arterial oxygenation (318 +/- 31.4 mmHg vs. 180 +/- 14.7 mmHg, P < 0.05), decreased BAL fluid neutrophil percentage (21 +/- 1.9 % vs. 30 +/- 5.6 %, P < 0.05), increased tissue nitrite level (32.55 +/- 4.12 nmol/g vs. 27.81 +/- 1.05 nmol/g, P < 0.05), and decreased tissue histopathological lesion scores (0.42 +/- 0.53 vs. 1.14 +/- 0.37, P < 0.05). This study suggests that nitric oxide donors supplemented during flush perfusion and reperfusion have more beneficial effects on lung functions against reperfusion injury than any other treatment modalities during IN SITU normothermic ischemic lung model.

Post-mortem Administration of Urokinase in Canine Lung Transplantation From Non–heart-beating Donors

We previously reported that post-mortem heparinization by closed-chest cardiac massage within 30 minutes after cardiac arrest is beneficial in lung transplantation (LTx) from non-heart-beating donors (NHBDs) by preventing formation of microthrombi. In this study, we evaluated the effects of post-mortem administration of urokinase 60 minutes after cardiac arrest. Left LTx was performed in 12 pairs of mongrel dogs. Donors were sacrificed and left at room temperature for 2 hours. In Group 1 (n = 6), heparin sodium (1,000 U/kg) was administered intravenously 60 minutes after cardiac arrest, then closed-chest cardiac massage was performed for 1 minute to distribute the heparin. In Group 2 (n = 6), the donors were treated as in Group 1, except, in addition to heparin sodium, urokinase (120,000 U) was administered intravenously before and at the end of cardiac massage. After 2 hours of cardiac arrest, donor lungs were flushed with low-potassium dextran glucose solution. After left LTx, the right pulmonary artery was ligated, and recipients were followed up for 3 hours. Uni- and multivariate repeat analyses were performed to obtain statistical data. Group 2 had significantly better arterial oxygen tension, lower pulmonary vascular resistance and lower wet/dry weight ratio of the transplanted lung than Group 1. d-dimer level during the warm ischemia was significantly lower in Group 2 than in Group 1. Post-mortem administration of urokinase along with heparin is beneficial in LTx from NHBDs by fibrinolytic action on already formed pulmonary microthrombi in the cadaver donor lungs.

Optimal Time for Post-mortem Heparinization in Canine Lung Transplantation with Non–heart-beating Donors

We previously reported that post-mortem heparinization by closed-chest cardiac massage is beneficial in lung transplantation from non-heart-beating donors by preventing formation of microthrombi. In this study, we evaluated the optimal time for post-mortem heparinization in canine lung transplantation from non-heart-beating donors. Left lung transplantation was performed in 25 weight-matched pairs of mongrel dogs. Donors were killed with an intravenous injection of potassium chloride and left at room temperature for 2 hours. The cadaver donors were assigned randomly to one of five study groups. In Group H0, heparin sodium (1,000 U/kg) was given intravenously before cardiac arrest. In Groups H10, H30, H45 and H60, heparin sodium (1,000 U/kg) was given intravenously 10, 30, 45 and 60 minutes after cardiac arrest, respectively, followed by closed-chest cardiac massage for 2 minutes. After 2 hours of cardiac arrest, donor lungs were flushed with low-potassium dextran glucose solution and preserved for 60 minutes. After left lung allotransplantation, the right pulmonary artery was ligated, and recipient animals were followed up for 3 hours. Uni- and multivariate repeat analyses were utilized for statistical assessment. After transplantation, gas exchange was significantly worse in Groups H45 and H60 than in Groups H0, H10 and H30. Thrombin/anti-thrombin III complex concentration during warm ischemia was significantly higher in Groups H30, H45 and H60 than in Groups H0 and H10. The optimal time for post-mortem heparinization in lung transplantation from non-heart-beating donors is approximately 30 minutes after cardiac arrest.

Effects of postmortem heparinization in canine lung transplantation with non–heart-beating donors

Microthrombus formation appears to be one of the major detrimental factors in lung transplantation from non-heart-beating donors. The purpose of this study was to evaluate the effects of postmortem heparinization by closed-chest cardiac massage in a canine model of left single-lung allotransplantation from non-heart-beating donors. Left lung transplantation was performed in 18 weight-matched pairs of mongrel dogs. Donors were killed with an intravenous injection of potassium chloride and left at room temperature for 2 hours. The cadaveric donors were assigned randomly to one of the three groups. In group 1 (n = 6), no heparin was given as a control. In group 2 (n = 6), heparin sodium (1000 U/kg) was administered intravenously before cardiac arrest. In group 3 (n = 6), heparin sodium (1000 U/kg) was administered intravenously 10 minutes after death, then closed-chest cardiac massage was performed for 2 minutes. After 2 hours of cardiac arrest, donor lungs were flushed with low-potassium dextran-glucose solution and preserved for 60 minutes. After left lung transplantation, the right pulmonary artery was ligated, and recipient animals were followed up for 3 hours. Univariate and multivariate repeated analyses were used for statistics. Both groups 2 and 3 had significantly better gas exchange and lower pulmonary vascular resistance than group 1. Changes in thrombin-antithrombin III complex concentration during the warm ischemia indicated that postmortem heparinization suppressed clotting activation in the donor. Postmortem heparinization by cardiac massage is beneficial in lung transplantation from non-heart beating donors by preventing microthrombus formation.

Comparison of canine single and sequential bilateral lung transplant model for lung preservation study

The purpose of this study was to compare canine sequential bilateral lung transplantation (SBLT) with left single lung transplant (LSLT) models. After 24 hours of lung preservation with low potassium/dextran glucose (LPDG) solution, seven SBLT procedures were performed using mongrel dogs. The comparative group including nine cases of LSLT. After completion of each transplant, the dogs were maintained on a ventilator for 3 hours. Thereafter serial hemodynamics were evaluated with recipients with chest X-ray, computed tomography, and lung perfusion scan checked at 2 hours after transplantation. Pathological evaluations were also performed. Five of seven SBLT successfully completed the whole assessment, all LSLT survived. In SBLT, pulmonary arterial pressure and pulmonary vascular resistance were significantly elevated, but recovered 3 hours after reperfusion. The ultrastructural aspects of alveolae and pulmonary artery endothelium showed a reversible mild injury 24 hours after lung preservation and reperfusion. The present study suggests that the canine SBLT model using LPDG solution provides an excellent preservation effect and is more physiological as the dog is completely dependent on the function of the transplanted lung.

Normal gas exchange after 30-h ischemia and treatment with phosphodiesterase inhibitor PDI747.

Phosphodiesterases (PDEs) negatively regulate the concentrations of cAMP and/or cGMP, which act as downstream second messengers to the prostaglandins. PDE type-4 (PDE4) is selective for cAMP and is found in high concentrations in endothelial, epithelial, and different blood cells. The aim of this study was to evaluate if PDI747, a novel selective inhibitor of PDE4, can restore pretransplant cAMP levels and thereby posttransplant organ function after prolonged cold ischemia. Left lung transplantation was performed in pigs (25-31 kg). Donor lungs were flushed with low potassium dextran glucose (LPDG) solution only (control, n=5)or, in addition with 1 micromol of PDI747 (PDI747, n=5) and stored for 30 h at 1 degrees C. PDI747 animals further received a bolus of PDI747 (0.3 mg/kg) 15 min prior to reperfusion and a continuous infusion (0.3 mg/kg per hour) during the 5 h after reperfusion. After occlusion of the right pulmonary arteries and the right main bronchus, hemodynamic and gas exchange parameters and extravascular lung water (EVLW) levels of the transplanted lung were assessed. Two control animals died of severe lung edema leading to heart failure (control, n=3). One animal in the treatment group was excluded due to a patent ductus arteriosus (PDI747, n=4). Gas exchange at the end of the experiment was restored to normal levels in the PDI747 group (Pa, O(2) 47.6+/-11.2 kPa, Pa,CO(2) 6.4+/-1.8 kPa) but not in the control group (Pa, O(2) 7.7+/-2.9 kPa, Pa, CO(2) 11.9+/-3.0 kPa, P(PaO2)<0.0001, P(Pa, CO2)=0.06). Extravascular lung water (EVLW) was normal in the PDI747 group (8.5+/-1.1 ml/kg) and clearly elevated in the control group (16.2+/-5.6 ml/kg, P=0.007). Airway pressure in the PDI747 group was significantly lower than in the control group (7.8+/-0.5 cm H(2)O vs. 11.3+/-0.6 cm H(2)O, respectively, P<0.0001). The free radical mediated tissue injury measured by lipid peroxidation (TBARS) was significantly reduced (P=0.001) in the PDI747 group. With the inhibition of PDE4 with PDI747 we achieved normal gas exchange, no posttransplant lung edema, normal airway pressures, and a reduced free radical injury after 30 h of cold ischemia.

Improved lung function by means of retrograde flush in canine lung transplantation with non-heart-beating donors

Objective: Use of lungs from non-heart-beating donors would increase the pulmonary donor pool. The aim of this study was to evaluate the effects of retrograde flush in canine lung transplantation from non-heart-beating donors. Methods: Left lung transplantation was performed in 12 weight-matched pairs of dogs. Donors were killed without heparinization, left at room temperature for 2 hours, and then randomized into 2 groups. In group AF (n = 6) lung retrieval was performed after flushing the lung block with low potassium dextran glucose (50 mL/kg) solution through the pulmonary artery. In group AF+RF (n = 6) additional retrograde flushing (low potassium dextran glucose, 25 mL/kg) was performed through the left atrium before retrieval. Flushed solution was sampled at intervals to measure hemoglobin concentrations. The lungs were preserved at 4°C for 2 hours, and the left lung was implanted to the recipient being subjected to a total ischemic time of 5 hours. After left lung transplantation, the right pulmonary artery and main bronchus were ligated. Lung function, including arterial blood gas and pulmonary hemodynamics, was measured for 3 hours. For lung function study, statistical analyses were performed by using 1-way analysis of variance with repeated measures. Results: Group AF+RF had significantly better gas exchange and lower wet/dry weight ratio of the transplanted lung than group AF. Changes of hemoglobin concentration in the flushed solution indicated that additional retrograde flush could remove residual microthrombi after antegrade flush. Conclusions: This study supports the theory that additional retrograde flush improves lung function after lung transplantation by removing residual pulmonary microthrombi in the lungs of non-heart-beating donors.J Thorac Cardiovasc Surg 2003;125:901-6

Trimetazidine protects the energy status after ischemia and reduces reperfusion injury in a rat single lung transplant model

Background: Ischemia-reperfusion injury involves free radical generation and polymorphonuclear neutrophil chemotaxis. Trimetazidine is an anti-ischemic drug that restores the ability of the ischemic cells to produce energy and reduces the generation of oxygen-derived free radicals. We evaluated the effect of trimetazidine against ischemia-reperfusion injury after lung transplantation. Methods: Rat single lung transplantation was performed in 3 experimental groups (n = 5): (1) the immediate transplantation group was defined as animals undergoing transplantation immediately after harvest without treatment; (2) the ischemic control group was defined as animals undergoing transplantation after 18 hours of cold (4°C) ischemia without treatment; and (3) the trimetazidine-treated group was defined as animals undergoing transplantation after 18 hours of cold (4°C) ischemia and donor and recipient treatment with 5 mg/kg intravenous trimetazidine 10 minutes before harvest and reperfusion, respectively. All donor lungs were flushed with low-potassium dextran-glucose solution. After 2 hours of reperfusion, oxygenation was measured, and lung tissue was frozen and assessed for adenosine triphosphate content, myeloperoxidase activity, and thiobarbituric acid–reactive substances. Peak airway pressure was recorded throughout the reperfusion period. Results: The trimetazidine group showed significantly higher levels of adenosine triphosphate content (1.73 ± 0.8 pmol vs 0.72 ± 0.2 pmol [ischemic control], P =.008), better oxygenation (238.82 ± 113.9 mm Hg vs 89.39 ± 14.7 mm Hg [ischemic control], P =.008), and reduced lipid peroxidation (1.28 ± 0.1 nmol/g vs 2.09 ± 0.4 nmol/g [ischemic control], P =.008). Adenosine triphosphate levels of the trimetazidine group were comparable with those of the immediate transplantation group (1.73 ± 0.8 pmol vs 1.89 ± 0.5 pmol, respectively; P =.31). Peak airway pressure and myeloperoxidase activity were comparable among groups. Conclusion: Donor and recipient treatment with trimetazidine provided a significant protection of the energy status, better oxygenation, and reduced lipid peroxidation in this experimental model. Our data suggest that trimetazidine may be an important adjunct to prolong ischemic time safely and to decrease lung ischemia-reperfusion injury.

Raffinose improves 24-hour lung preservation in low potassium dextran glucose solution: a histologic and ultrastructural analysis

Background. We have previously shown that the addition of raffinose to low potassium dextran (LPD) preservation solution improves transplanted rat lung function after 24 hours of storage. The mechanisms by which raffinose acts are unclear. The aim of this study was to examine the histologic and ultrastructural correlates of this enhanced pulmonary function after preservation with raffinose. Methods. In a randomized, blinded study, rat lungs were flushed with LPD, or LPD containing 30 mmol/L of raffinose, and stored for 24 hours at 4°C. Control lungs were flushed with LPD but not stored (n = 5 each group). Changes in postpreservation edema were determined. In addition, lungs were flushed with a trypan blue solution to quantify cell death, and examined using both light and electron microscopy. Results. The LPD lungs gained significantly more weight (25.5% ± 5.5%) compared with raffinose-LPD lungs (5.2% ± 5.3%; p < 0.0001). There were higher percentages of dead cells in the LPD lungs (29% ± 0.3% of total cells) compared with raffinose-LPD lungs (14% ± 1.4%; p < 0.001) and control lungs (0.2% ± 5%; p < 0.001). Control lungs maintained normal ultrastructure, whereas LPD lungs showed a decreased number of intact type II pneumocytes and significant cellular necrosis. Interstitial and alveolar edema with interstitial macrophage infiltration was also observed. Alveolar capillaries were collapsed. In contrast, raffinose-LPD lungs showed only mild alterations such as minimal interstitial edematous expansion, fewer damaged cells, and minimal capillary injury. Conclusions. Raffinose exerts a cytoprotective effect on pulmonary grafts during preservation, which explains the previously documented improved function. This simple modification of LPD with raffinose may provide clinical benefit in extended pulmonary preservation.

Ultrastructural evaluation of preservation and reperfusion effects of low potassium dextran glucose solution in canine allograft lungs

Ultrastructural evaluation of preservation and reperfusion effects of low potassium dextran glucose solution in canine allograft lungs

A novel cell culture model for studying ischemia-reperfusion injury in lung transplantation.

Many cell culture models have been developed to study ischemia-reperfusion injury; however, none is specific to the conditions of lung preservation and transplantation. The objective of this study was to design a cell culture model that mimics clinical lung transplantation, in which preservation is aerobic and hypothermic. A549 cells, a human pulmonary epithelial cell line, were preserved in 100% O(2) at 4 degrees C for varying periods in low-potassium dextran glucose solution, simulating ischemia, followed by the introduction of warm (37 degrees C) DMEM plus 10% fetal bovine serum to simulate reperfusion. Cultures were assayed for cell attachment and viability. Sequential extension of ischemic times to 24 h showed a time-dependent loss of cells. There was a further decrease in cell number after simulated reperfusion. Cell detachment was due mainly to cell death, as determined by cell viability. The effects of chemical components such as dextran 40 and calcium in the preservation solution and various preservation gas mixtures were examined by use of this model system. With its design and validation, this model could be used to study mechanisms related to ischemia-reperfusion injury at the cellular and molecular level.

Inhibition of angiotensin-converting enzyme by captopril: A novel approach to reduce ischemia-reperfusion injury after lung transplantation

Objectives: Ischemia-reperfusion injury after lung transplantation involves the generation of free radicals. Captopril has been shown to be protective in models of ischemia-reperfusion injury in other organs by acting as a free radical scavenger. The purpose of this study was to assess the protective effects of captopril against ischemia-reperfusion injury and to evaluate the ability of captopril to scavenge free radicals and inhibit neutrophil activation in an experimental model of lung transplantation. Methods: A rat single-lung transplant model was used. Donor lungs were flushed and preserved in low-potassium dextran-glucose solution with (n = 5) and without captopril (500 μmol/L; n = 5) for 18 hours at 4°C and then transplanted and reperfused for 2 hours. At the conclusion of the 2-hour reperfusion period, arterial blood gases, blood pressure, and peak airway pressure were measured. Lung tissue biopsy specimens were obtained for assessment of wet/dry weight ratios, histology, and neutrophil sequestration (myeloperoxidase activity). Lipid peroxidation (F2-isoprostane assay) was analyzed from plasma samples and tissue lysates. Results: The addition of captopril to the lung preservation solution significantly improved postreperfusion PO2 (312 ± 63.3 mm Hg vs 202 ± 21.1 mm Hg; P =.006), peak airway pressure (11.4 ± 1.1 cm H2O vs 15.6 ± 1.5 cm H2O; P =.001), and wet/dry weight ratio (4.9 ± 0.4 vs 15.8 ± 10.9; P =.008). Blood pressures did not differ significantly between groups. No significant differences were seen in myeloperoxidase activity or F2-isoprostane levels. Conclusions: The use of captopril in the preservation solution ameliorates ischemia-reperfusion injury in transplanted lungs after an extended cold preservation period. The mechanisms by which captopril is protective remain elusive but do not appear to include inhibition of neutrophil sequestration or lipid peroxidation. This novel approach to ischemia-reperfusion injury may lead to improved lung function after transplantation and provide further insight into the pathogenesis of acute lung injury. (J Thorac Cardiovasc Surg 2000;120:573-80)