Histologic and functional evaluation of lungs reconditioned by ex vivo lung perfusion

BACKGROUND: Only about 15% of donor lungs are considered suitable for transplantation (LTx). Ex vivo lung perfusion (EVLP) has been developed as a method to reassess and repair damaged lungs. We report our experience with EVLP in non-acceptable donor lungs and evaluate its ability to recondition these lungs. METHODS: We studied lungs from 16 brain-dead donors rejected for LTx. After harvesting, the lungs were stored at 4 degrees C for 10 hours and subjected to normothermic EVLP with Steen Solution (Vitro life, Goteborg, Sweden) for 60 minutes. For functional evaluation, the following variables were assessed: partial pressure of arterial oxygen (Pao(2)), pulmonary vascular resistance (PVR), and lung compliance (LC). For histologic assessment, lung biopsy was done before harvest and after EVLP. Tissue samples were examined under light microscopy. To detect and quantify apoptosis, terminal deoxynucleotide transferase-mediated deoxy uridine triphosphate nick-end labeling assay was used. RESULTS: Thirteen lima donors were refused for having impaired lung function. The mean Pao(2) obtained in the organ donor at the referring hospital was 193.7 mm Hg and rose to 489 mm Hg after EVLP. During EVLP, the mean PVR was 652.5 dynes/sec/cm(5) and the mean LC was 48 ml/cm H2O. There was no significant difference between the mean Lung Injury Score before harvest and after EVLP. There was a trend toward a reduction in the median number of apoptotic cells after EVLP. CONCLUSIONS: EVLP improved lung function (oxygenation capacity) of organs considered unsuitable for transplantation. Lung tissue structure did not deteriorate even after 1 hour of normothermic perfusion. J Heart Lung Transplant 2012;31:305-9 (C) 2012 International Society for Heart and Lung Transplantation. All rights reserved.

ROLE OF FOCAL ADHESION KINASE IN LUNG REMODELING OF ENDOTOXEMIC RATS

Despite significant advances in the care of critically ill patients, acute lung injury continues to be a complex problem with high mortality. The present study was designed to characterize early lipopolysaccharide (LPS)-induced pulmonary injury and small interfering RNA targeting focal adhesion kinase (FAK) as a possible therapeutic tool in the septic lung remodeling process. Male Wistar rats were assigned into endotoxemic group and control group. Total collagen deposition was performed 8, 16, and 24 h after LPS injection. Focal adhesion kinase expression, interstitial and vascular collagen deposition, and pulmonary mechanics were analyzed at 24 h. Intravenous injection of small interfering RNA targeting FAK was used to silence expression of the kinase in pulmonary tissue. Focal adhesion kinase, total collagen deposition, and pulmonary mechanics showed increased in LPS group. Types I, III, and V collagen showed increase in pulmonary parenchyma, but only type V increased in vessels 24 h after LPS injection. Focal adhesion kinase silencing prevented lung remodeling in pulmonary parenchyma at 24 h. In conclusion, LPS induced a precocious and important lung remodeling. There was fibrotic response in the lung characterized by increased amount in total and specific-type collagen. These data may explain the frequent clinical presentation during sepsis of reduced lung compliance, oxygen diffusion, and pulmonary hypertension. The fact that FAK silencing was protective against lung collagen deposition underscores the therapeutic potential of FAK targeting by small interfering RNA.

Comparison of lung preservation solutions in human lungs using an ex vivo lung perfusion experimental model

OBJECTIVE: Experimental studies on lung preservation have always been performed using animal models. We present ex vivo lung perfusion as a new model for the study of lung preservation. Using human lungs instead of animal models may bring the results of experimental studies closer to what could be expected in clinical practice. METHOD: Brain-dead donors whose lungs had been declined by transplantation teams were used. The cases were randomized into two groups. In Group 1, Perfadex (R) was used for pulmonary preservation, and in Group 2, LPDnac, a solution manufactured in Brazil, was used. An ex vivo lung perfusion system was used, and the lungs were ventilated and perfused after 10 hours of cold ischemia. The extent of ischemic-reperfusion injury was measured using functional and histological parameters. RESULTS: After reperfusion, the mean oxygenation capacity was 405.3 mmHg in Group 1 and 406.0 mmHg in Group 2 (p=0.98). The mean pulmonary vascular resistance values were 697.6 and 378.3 dyn.s.cm(-5), respectively (p=0.035). The mean pulmonary compliance was 46.8 cm H2O in Group 1 and 49.3 ml/cm H2O in Group 2 (p=0.816). The mean wet/dry weight ratios were 2.06 and 2.02, respectively (p=0.87). The mean Lung Injury Scores for the biopsy performed after reperfusion were 4.37 and 4.37 in Groups 1 and 2, respectively (p=1.0), and the apoptotic cell counts were 118.75/mm(2) and 137.50/mm(2), respectively (p=0.71). CONCLUSION: The locally produced preservation solution proved to be as good as Perfadex (R). The clinical use of LPDnac may reduce costs in our centers. Therefore, it is important to develop new models to study lung preservation.