Modelo experimental de perfusão pulmonar ex vivo em ratos: avaliação histopatológica e de apoptose celular em pulmões preservados com solução de baixo potássio dextrana vs. solução histidina-triptofano-cetoglutarato

Abstract

Objective: To compare histopathological findings and the degree of apoptosis among rat lungs preserved with low-potassium dextran (LPD) solution, histidine-tryptophan-ketoglutarate (HTK) solution, or normal saline (NS) at two ischemia periods (6 h and 12 h) using an experimental rat model of ex vivo lung perfusion. Methods: Sixty Wistar rats were anesthetized, randomized, and submitted to antegrade perfusion via pulmonary artery with one of the preservation solutions. Following en bloc extraction, the heart-lung blocks were preserved for 6 h or 12 h at 4°C and then reperfused with homologous blood for 60 min in an ex vivo lung perfusion system. At the end of the reperfusion, fragments of the middle lobe were extracted and processed for histopathological examination. The parameters evaluated were congestion, alveolar edema, alveolar hemorrhage, inflammatory infiltrate, and interstitial infiltrate. The degree of apoptosis was assessed using the TdT-mediated dUTP nick end labeling method. Results: The histopathological examination showed that all of the lungs preserved with NS presented alveolar edema after 12 h of ischemia. There were no statistically significant differences among the groups in terms of the degree of apoptosis. Conclusions: In this study, the histopathological and apoptosis findings were similar with the use of either LPD or HTK solutions, whereas the occurrence of edema was significantly more common with the use of NS. Keywords: Organ preservation; Organ preservation solutions; Lung transplantation; Reperfusion injury; Apoptosis. ResumoObjetivo: Comparar os achados histopatológicos e de apoptose em pulmões de ratos preservados em soluções low-potassium dextran (LPD, baixo potássio dextrana), histidine-tryptophan-ketoglutarate (HTK, histidina-triptofano-cetoglutarato) ou salina normal (SN) em 6 h e 12 h de isquemia pela utilização de um modelo experimental de perfusão pulmonar ex vivo. Métodos: Sessenta ratos Wistar foram anestesiados, randomizados e submetidos à perfusão anterógrada pela artéria pulmonar com uma das soluções preservadoras. Após a extração, os blocos cardiopulmonares foram preservados por 6 ou 12 h a 4°C, sendo então reperfundidos com sangue homólogo em um sistema de perfusão ex vivo durante 60 min. Ao final da reperfusão, fragmentos do lobo médio foram extraídos e processados para histopatologia, sendo avaliados os seguintes parâmetros: congestão, edema alveolar, hemorragia alveolar, hemorragia, infiltrado inflamatório e infiltrado intersticial. O grau de apoptose foi avaliado pelo método TdT-mediated dUTP nick end labeling. Resultados: A histopatologia demonstrou que todos os pulmões preservados com SN apresentaram edema alveolar após 12 h de isquemia. Não houve diferenças em relação ao grau de apoptose nos grupos estudados. Conclusões: No presente estudo, os achados histopatológicos e de apoptose foram semelhantes com o uso das soluções LPD e HTK, enquanto a presença de edema foi significativamente maior com o uso de SN. Descritores: Preservação de órgãos; Soluções para...

Lung Protection Strategies during Cardiopulmonary Bypass Affect the Composition of Bronchoalveolar Fluid and Lung Tissue in Cardiac Surgery Patients

“…Its buffer system is thought to withdraw extracellular sodium and calcium, together with buffering of the extracellular space by means of histidine and histidine-hydrochloride, thus prolonging the period during which organs tolerates interruption in blood supply [31]. It has been found that HTK solution attenuated pulmonary edema until 12 h post-perfusion when compared to both saline and the low-potassium dextran preservation solution in an experimental rat model of ex vivo lung perfusion [32]. In the randomized Pulmonary Protection Trial of adult patients undergoing elective cardiac surgery [26], we found that postoperative arterial oxygenation on the first postoperative day was slightly better following pulmonary artery perfusion with normothermic oxygenated blood during CPB compared to pulmonary artery perfusion with hypothermic HTK solution and standard regimen with no perfusion.…”

Publicações do Jornal Brasileiro de Pneumologia

“…There were three studies involving ex vivo experimental models. ( 13 - 15 ) The use of a surgical adhesive for lung repair after lobectomy was tested in rats, ( 16 ) the extracellular matrix of the rat trachea was examined, ( 17 ) an experimental rat model of pulmonary hypertension ( 18 ) was studied, and the use of a self-expanding tracheal stent was tested in rabbits. ( 19 ) Murine models of allergic response ( 20 ) and of protective ventilation strategies ( 21 ) were studied.…”