Filtration coefficient in isolated preserved and reperfused canine lung

Protective effects of inhaled nitric oxide and gabexate mesilate in lung reperfusion injury after transplantation from non-heart-beat donors

BACKGROUND

The use of lung grafts from non-heart-beat donors (NHBDs) is one way of solving the critical donor organ shortage. Inhaled nitric oxide (NO) and gabexate mesilate (FOY), a protease inhibitor, can attenuate some types of neutrophil-mediated tissue injury. Using an isolated lung ventilation and perfusion model, we studied the effects of these agents on reperfusion injury following lung transplantation from NHBDs.

METHODS

Five groups of minipigs were studied. In group 1(n = 6), the lungs were flushed and harvested after cardiac arrest, and were reperfused for 2 hours after 2 hours of cold ischemia. In group 2 (n = 6), the lungs were harvested after 2 hours of in situ warm ischemia, followed by 2 hours of cold ischemia and 2 hours of reperfusion. In groups 3 (n = 7), 4 (n = 7), and 5 (n = 6), the procedure was the same as in group 2, except in group 3, NO was inhaled before and after ischemia, in group 4, FOY was given intravenously, and in group 5, a combination of inhaled NO and intravenous FOY were administered.

RESULTS

Compared with group 1, group 2 had higher mean pulmonary arterial pressure, vascular resistance, and lower arterial blood oxygen tension. Furthermore, these negative effects of warm ischemia were also reflected in the contents of bronchoalveolar lavage fluid, tissue myeloperoxidase (MPO) activity, histology, and permeability change. Either FOY or NO administration (groups 3 or 4) ameliorated the associated injury. A combination of FOY and NO use (group5) decreased the parameters of lung reperfusion injury measurement to a larger degree than either agent individually.

CONCLUSIONS

The inhaled NO and FOY can protect NHBD lung grafts at an early reperfusion period. Their use in combination has an additive protective effect that might be applied to the protection of NHBD grafts from preservation and reperfusion injury.

A novel paracorporeal method for isolated rodent lung reperfusion

BACKGROUND

The isolated perfused lung model is commonly used in small animals to study lung function after preservation and cold storage. Measurements of oxygenation, compliance, and capillary filtration coefficient (Kf) permit analysis of preservation solutions or modifications of these solutions. However, inter-investigator variability using different perfusates makes comparisons difficult. Whole blood perfusion more closely mimics the in vivo situation, but extracorporeal circulation may alter the physiologic integrity of the model. Paracorporeal support has been used, but this technique required mechanical ventilation of the support rodent and did not incorporate a method for determining Kf. We evaluated a less-invasive technique, of providing cross-circulatory syngeneic support, maintaining the ability to compute Kf.

METHODS

Angiocatheters were inserted into both femoral arteries and one femoral vein of the support rat. The venous cannula was connected to the pulmonary artery of the ex vivo lung block to provide inflow. Pulmonary effluent blood from the lung block was collected via a left atrial cannula and returned to the support rat via the femoral artery. A separate, height-adjustable column was included in the circuit for measurement of Kf.

RESULTS

Each support rat was used to sequentially perfuse three double-lung blocks. The inflow sample to each lung block was analyzed for pH, pO2, pCO2, and hematocrit to follow alterations in support rat physiology. There were no statistical differences in the pH, PO2, or hematocrit. No significant differences were noted in the pO2 of the pulmonary effluent blood or the Kf; analyzed to determine whether the sequence of reperfusion affected the pulmonary function assessment.

CONCLUSIONS

The syngeneic support rat delivers constant pressure systemic venous blood at stable physiologic parameters to the ex vivo lung block. Recirculation of the perfusate through the support rat diminishes the need to pool blood from donors, detoxifies and deoxygenates pulmonary effluent blood, and permits examination of sequential lung blocks. This technique represents a hybrid model between isolated perfused and orthotopic transplant models, maintaining Kf determination, a sensitive indicator of reperfusion injury. This technique could be applicable to reperfusion injury models of other organs (using arterial inflow instead) and may permit increased standardization among investigators.

Platelet activating factor acetylhydrolase decreases lung reperfusion injury

BACKGROUND

Ischemia-reperfusion injury involves free radical production, polymorphonuclear neutrophil chemotaxis/degranulation, and production of proteolytic enzymes, complement components, coagulation factors, and cytokines. Activated polymorphonuclear neutrophils, endothelial cells, and macrophages produce platelet activating factor, which further promotes these inflammatory reactions. The recently cloned plasma form of platelet activating factor-acetylhydrolase (PAF-AH) demonstrates antiinflammatory effects by degrading platelet activating factor. We evaluated the effects of PAF-AH in an isolated perfused rat lung model by adding it to the flush solutions or to the reperfusion blood.

METHODS

Rat lungs were isolated, flushed with EuroCollins (EC) or University of Wisconsin (UW) solution, stored at 4 degrees C for 6 or 12 hours, and reperfused using a cross-circulating syngeneic support rat. During reperfusion, oxygenation, compliance, and capillary filtration coefficient were calculated. There were four groups in the study; group I (control) had no PAF-AH added, group II had PAF-AH added to the flush solution, group III had PAF-AH added to reperfusion blood, and group IV had PAF-AH added to both flush solution and reperfusion blood.

RESULTS

After 6 hours of storage, oxygenation, compliance, and capillary filtration coefficient significantly improved for EC in group IV. For UW, oxygenation improved in group IV whereas compliance improved in groups II, III, and IV. After 12 hours of storage, compliance improved for EC in group IV and capillary filtration coefficient improved in groups III and IV. For UW, oxygenation and compliance improved in groups II and IV, whereas capillary filtration coefficient improved in group IV.

CONCLUSIONS

Addition of PAF-AH to intracellular organ preservation solutions and to the blood reperfusate significantly improves postreperfusion oxygenation and compliance, and reduces lung capillary permeability.

The effect of FR167653 on pulmonary ischemia-reperfusion injury in rats

BACKGROUND

A novel synthesized organic compound, FR167653, has been characterized as a potent suppressant of interleukin-1 and tumor necrosis factor-alpha. We designed this experimental study to evaluate the effect of FR167653 on ischemia-reperfusion injury of the rat lung.

METHODS

Following general anesthesia, the left bronchus, pulmonary artery and vein were clamped for 1 hour. FR167653 was administered continuously beginning 30 minutes before the onset of ischemia and extending for 2 hours after reperfusion. Thirty-eight Wistar rats were divided into 4 groups according to the dose of FR167653 at the rate of 0.1, 0.05 and 0.025 mg/kg/hr in each group. After the optimal dose was obtained from the result of 1-week survival rate, the group with the optimal dose was compared with a control group by using such parameters as arterial oxygen saturation (SaO(2)), arterial oxygen tension (PaO(2)), cytokines, the expression of p38 MAP kinase and histologic study.

RESULTS

Survival rate of the group received FR at the rate of 0.1 mg/kg/hr (FR0.1 group) was best among the 4 groups. SaO(2) levels and PaO(2) levels after 2-hour of reperfusion were significantly (p < 0.05, respectively) higher in the FR0.1 group than in the control group. After 2-hour reperfusion, IL-1 beta was lower in the FR0.1 group than in the control group, and the expression of p38 MAP kinase was reduced in the FR0.1 group compared with the control group. In histologic study after 2-hour of reperfusion, alveolar damage with edema and interstitial thickening localized along the alveolar duct were observed in the control group, whereas these findings were remarkably less evident in the FR0.1 group.

CONCLUSIONS

We concluded that FR167653 ameliorates ischemia-reperfusion injury of the lung and may inhibit the production of proinflammatory cytokines by means of the inhibition of p38 MAP kinase.

Microvascular permeability of the non-heart-beating rabbit lung after warm ischemia and reperfusion: role of neutrophil elastase

BACKGROUND

The duration of warm ischemia and reperfusion injury is a major limiting factor in the setting of lung transplantation with non-heart-beating donors (NHBD). We hypothesized that reperfusion with neutrophil elastase inhibitor or leukocyte-depleted blood has an inhibitory effect on the ischemia-reperfusion injury of NHBD rabbit lungs.

METHODS

To assess the lung injury, we used a perfused rabbit lung model and measured the hemodynamic parameters and filtration coefficient. The rabbit lungs after hypoxic cardiac arrest for 30, 50, and 60 minutes were harvested at room temperature, and ventilated lungs were reperfused for 1 hour at a constant flow (120 mL/min). The group with 60 minutes of warm ischemia and hypoxia was further divided into three groups to determine the effects of leukocyte-depleted reperfusion or neutrophil elastase inhibitor, (1) no other special treatment, (2) reperfusion with leukocyte-depleted blood, and (3) administration of 10 mg of specific neutrophil elastase inhibitor. The lungs reperfused immediately after harvest from the heart-beating donor were regarded as the control.

RESULTS

Sixty minutes of warm ischemia and hypoxia resulted in an increase in filtration coefficient (0.68+/-0.20 g x min(-1) x cm H2O(-1) per 100 g) compared with the control values of 0.13+/-0.03 g x min(-1) x cm H2O(-1) per 100 g. The increase in filtration coefficient after 60 minutes of warm ischemia and hypoxia in NHBD was remarkably suppressed by leukocyte depletion (0.23+/-0.07) and by neutrophil elastase inhibitor (0.21+/-0.08). The shunt fraction and histology results were also near normal.

CONCLUSIONS

These results suggested that leukocyte depletion or treatment with neutrophil elastase inhibitor during reperfusion reduces alveolar-capillary damage caused by lung ischemia-reperfusion injury in the NHBD lung transplantation setting. This effect might be mediated by inhibition of neutrophil elastase activity or sequestration, and thus may lead to the increased availability of NHBD lungs.

PGE1, dexamethasone, U-74389G, or Bt2-cAMP as an additive to promote protection by UW solution in I/R injury

A method to reduce ischemia-reperfusion (I/R) injury can be an important criterion to improve the preservation solution. Although University of Wisconsin solution (UW) works as a lung preservation solution, its attenuation effect on I/R injury has not been investigated. We attempted to determine whether, by adding various protective agents, modified UW solutions will enhance the I/R attenuation by UW. We examined the I/R injury in an isolated rat lung model. Various solutions, e.g., physiological salt solution (PSS), UW, and modified UW solutions containing various protective agents such as prostaglandin E1, dexamethasone, U-74389G, or dibutyryl adenosine 3',5'-cyclic monophosphate were perfused individually to evaluate the I/R injury. Isolated rat lung experiments, with ischemia for 45 min, then reperfusion for 60 min, were conducted in a closed circulating system. Hemodynamic changes, lung weight gain (LWG), capillary filtration coefficient (Kfc), protein content of lavage fluid, concentration of cytokines, and lung histopathology were analyzed. Results showed that the acute I/R lung injury with immediate permeability pulmonary edema was associated with an increase in tumor necrosis factor-alpha (TNF-alpha) production. A significant correlation existed between TNF-alpha and Kfc (r = 0.8, P < 0.0001) and TNF-alpha and LWG (r = 0. 9, P < 0.0001), indicating that TNF-alpha is an important cytokine modulating early I/R injury. Significantly lower levels of Kfc, LWG, TNF-alpha, and protein concentration of lung lavage (P < 0.05) were found in the UW-perfused group than in the control group perfused with PSS. Modified UW promoted the protective effect of UW to further decrease Kfc, LWG, and TNF-alpha (P < 0.05). Histopathological observations also substantiated this evidence. In the UW+U-74389G group, bronchial alveolar lavage fluid contained lowest protein concentration. We conclude that the UW solution attenuates I/R injury of rat lung and that the modified UW solutions further enhance the effect of UW in reducing I/R injury. Among modified solutions, UW+U-74389G is the best. Further investigation of the improved effects of the modified UW solutions would be beneficial in lung transplantation.

Prevention of reperfusion injury by inhaled nitric oxide in lungs harvested from non-heart-beating donors. Paris-Sud University Lung Transplantation Group

BACKGROUND

In lung transplantation using non-heart-beating donors (NHBD), the postmortem period of warm ischemia exacerbates lung ischemia-reperfusion injury. We hypothesized that inhaled nitric oxide (NO) would reduce ischemia-reperfusion injury, and thus ameliorate the viability of the lung graft.

METHODS

A blood-perfused, isolated rat lung model was used. Lungs were flushed and harvested from non-heart-beating donors after 30 minutes of in situ warm ischemia. The lung was then stored for 2 hours at 4 degrees C. Inhaled NO at 30 ppm was given either during the period of warm ischemia, during reperfusion, or during both periods. Lung ischemia-reperfusion injury was assessed after 1 hour of reperfusion by measuring pulmonary vascular resistance, coefficient of filtration, wet-to-dry lung weight ratio, and myeloperoxidase activity.

RESULTS

A severe IR injury occurred in lungs undergoing ischemia and reperfusion without NO as evidenced by high values of pulmonary vascular resistance (6.83 +/- 0.36 mm Hg. mL-1.min-1), coefficient of filtration (3.02 +/- 0.35 mL.min-1.cm H2O-1 x 100 g-1), and wet-to-dry lung weight ratio (8.07 +/- 0.45). Lower values (respectively, 3.31 +/- 0.44 mm Hg.mL-1.min-1, 1.49 +/- 0.34 mL.min-1.cm H2O-1 x 100 g-1, and 7.44 +/- 0.43) were observed when lungs were ventilated with NO during ischemia. Lung function was further improved when NO was given during reperfusion only. All measured variables, including myeloperoxidase activity were significantly improved when NO was given during both ischemia and reperfusion. Myeloperoxidase activity was significantly correlated with coefficient of filtration (r = 0.465; p < 0.05).

CONCLUSIONS

These data suggest that inhaled NO significantly reduces ischemia-reperfusion injury in lungs harvested from non-heart-beating donors. This effect might be mediated by inhibition of neutrophil sequestration in the reperfused lung.

Heart and Heart-Lung Transplantation: An Update

Heart and heart-lung transplantation have been established as effective treatments for a wide variety of end-stage cardiopulmonary diseases. Recent years have seen refinements in surgical techniques for cardiopulmonary replacement as well as the selection and postoperative care of thoracic transplant recipients. Despite substantial clinical progress, however, significant problems remain, particularly donor organ shortage, graft rejection, opportunistic infection, and limited organ preservation techniques. Basic and clinical research are currently addressing these problems. In this brief review, we provide an update of our experiences with heart and heart-lung transplantation in the West (particularly at Stanford University), an outline of the active issues in the field, and some thoughts about the development of thoracic transplantation in Asia.

Changes in vascular permeability with ischemic time, temperature, and inspired oxygen fraction in isolated rabbit lungs

The capillary filtration coefficient (Kf) is one of the most accurate measures of change in pulmonary vascular permeability and has been used in various models of acute lung injury. To evaluate the isolated effects of ischemia on Kf, we have developed an ex vivo rabbit lung model in which the influences of reperfusion are eliminated. The current study was designed to validate this model by determining the effect of cold flushing with low-potassium-dextran solution containing 1% glucose (LPDG), ischemic time, temperature, and inspired oxygen fraction on Kf. On completion of the ischemic period, the ventilated lungs, with the heart still attached, were suspended from a strain-gauge force transducer. After the lungs were flushed with 50 mL hetastarch solution (6% hetastarch solution with physiologic saline solution), the left atrial drainage cannula was occluded and the pulmonary artery pressure was incrementally increased by elevation of the reservoir. The Kf was calculated as the slope of the line relating the weight gain rate and pulmonary capillary pressure.(ABSTRACT TRUNCATED AT 250 WORDS)