RESUMO
Skin wound healing is a complex process involving different events such as blood coagulation, inflammation, new blood vessels formation, and extracellular matrix deposition. These events can be observed by using histology techniques. However, the lack of the standardization of such parameters impacts on the reproducibility of results. Here, we describe a protocol to perform macroscopic and microscopic analyses of the events that occur during skin wound healing using the experimental model of excisional wounds in rats.
RESUMO
Introduction: Aspiration of gastric content is associated with a wide range of clinical conditions (acute lung injury, severe interstitial pneumonia or bronchiolitis obliterans following lung transplantation). Objective: To study the course of histological alterations in a model of intra-tracheal instillation of gastric juice in rats. Methods: Anesthetized rats were euthanized at different times: 4, 12 and 24 hours and 4 and 7 days after intratacheal (IT) instillation of gastric juice. Animals that were not intervened served as controls. The right inferior lobe was studied (H-E) and a histological injury score was given according to a recently published score system. Results: Between 4-24 h an inflammatory-hemorragic pattern with bronchiol-centric distribution was characterized by a large proportion of neutrophils in both alveoli and interstitium, alveolarfluid accumulation, proteinaceous material andfew hyaline membranes. Between 4 and 7 days, mononuclear cells were more prevalent, the hemorrhagic component disappeared, the percentage of abnormal bronchioles was significantly reduced and there was organization of the alveolar infiltrate, with Masson bodies, granulomas and giant cells associated with gastric juice particles. Conclusions: In rats, IT instillation of gastric juice induces diffuse alveolar damage that evolves towards an early granulomatous interstitial pneumonia along with lax fibrous tissue. Knowledge of the temporary course of the pulmonary responses helps to the understanding of the consequences of the several clinical conditions that favor gastric content aspiration.
Introducción: La aspiración de contenido gástrico se asocia con diversas condiciones clínicas (daño pulmonar agudo, neumonía intersticial severa o bronquiolitis obliterante post-trasplante). Objetivo: Estudiar el curso de las alteraciones histológicas en un modelo de instilación intra-traqueal (IT)de jugo gástrico en ratas. Métodos: Ratas anestesiadas recibieron vía ITjugo gástrico de un pool obtenido previamente. Los animales fueron sacrificados a las: 4, 12 y 24 h y 4 y 7 días post-instilación. Animales sin intervención sirvieron como controles. El lóbulo inferior derecho fue estudiado (H-E) para la asignación de un puntaje de daño histológico de acuerdo a un sistema de puntuación recientemente publicado. Resultados: Entre 4-24 h se observó un patrón inflamatorio-hemorrágico de distribución bronquíolo-céntrica, con predominio de neutrófilos intersticiales y alveolares, edema, material proteináceo alveolar y escasas membranas hialinas. Entre los 4 y 7 días, se observó predominio mononuclear y desaparición del componente hemorrágico, se redujo significativamente el porcentaje de bronquíolos afectados y se observó organización del infiltrado inflamatorio, con cuerpos de Masson, granulomas y células gigantes asociadas a partículas del jugo gástrico. Conclusiones: En ratas, la instilación IT de jugo gástrico induce daño alveolar difuso que progresa hacia una neumonía intersticial granulo-matosa temprana con tejido fibroso laxo. El conocimiento del curso de la respuesta pulmonar en este modelo, contribuye a comprender las posibles consecuencias de las condiciones clínicas que favorecen la aspiración de contenido gástrico.