| Objective: To investigate the effects of microRNA-21-5p on the Lungs ofhyperoxia-induced acute lung injury rats and provide a theoretical basis for gene therapy ofhyperoxia-induced acute lung injury.Method:160SD rats were randomly divided into four groups (n=40), comparison group,PBS group, empty virus group and miRNA-21-5p group. The rats of four groups wereplaced in a homemade high oxygen box to feed. Randomly selected10rats from hyperoxia0h,24h,48h and72h and anesthetized them at intraperitoneal. Then extract1ml arterialblood detect gas to analyze and calculate the oxygenation index (OI) and respiratory index(RI); observe the general changes of the lung tissue; take the right lung of rats and makeHE staining. Then use optical microscope to observe the pathology change and mark itwith scores; and take the left lung to measure wet/dry ratio (W/D).Results:（1）The change of respiratory function: Intra-group comparison, with theextension of time, the OI gradually decreased in comparison group, the PBS group, and theempty virus group while RI gradually increased (P <0.05); The within group comparisons:In hyperoxia24h,48h and72h, the OI of miRNA-21-5p group was significantly higherthan comparison among PBS and empty virus groups, however, the RI of this group islower than other three groups(P <0.05)；（2）The naked eye changes of the lung tissue: Inhyperoxia0h, each group of lung tissue was soft with slightly pink color; In hyperoxia24h,the lung tissue was pale red, the surface were scattered with bleeding point in differentsizes, and the lung tissue swelled; in hyperoxia48h and72h, the lung tissue appeared to becongestion with blood, and became edema with dark red color, the lung surface appearedmany visible bleeding points and bleeding patchy, the lung tissue was swelled significantly,some rats even have yellow or red pleural effusion; but the miRNA-21-5p group’s changeis comparatively less than other three groups;（3）Change of lung tissue under opticalmicroscope: in hyperoxia0h, the structures of lung tissue were clear for all groups; In hyperoxia24h, the structure of lung tissue in each group, there were slightly widening ofalveolar septal, with little edema and a small amount of inflammatory cell infiltration; Inhyperoxia48h and72h, the structures of lung tissue were disordered, the section alveolarwalls were fractured and damaged of the Comparison group, the PBS group and emptyvirus group, there were significant widening, edema and a large number of inflammatorycells infiltration in alveolar septal and there were edema fluid, inflammatory cells and evena small amount of red blood cells appeared in alveolar cavities, but the pathology damagedegree of lung tissue of miRNA-21-5p group was less than above three groups.（4）Thepathologic scores of lung tissue: Intra-group comparison, with the extension of time, thepathologic scores of lung tissue of each group were gradually increased (P <0.05); Thewithin group comparisons: In hyperoxia24h,48h, and72h, the pathologic scores ofmiRNA-21-5p group was significantly lower than other three groups (P <0.05).（5）TheW/D of lung tissue: Intra-group comparison, with the extension of time, the W/D ratio oflung tissue of each group was gradually increased (P <0.05), The within groupcomparisons: In hyperoxia24h,48h, and72h, the W/D of miRNA-21-5p group was lowerthan other three groups (P <0.05).Conclusion:（1） Sustained high levels of oxygen (>90%) can cause lung injury of rats after24hours, then it can establish the HALI model successfully;（2） Slow virus vector can be successful transfection of miRNA-21-5p, and for a longtime to express in the body;（3）The miRNA-21-5p has certain protective effect in lung tissue of HALI rats. |
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