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Abstract The protective effect of microRNA (miR)‐145‐5p in acute lung injury (ALI) has been discovered previously. Thus, in this study, we attempted to further investigate the mechanism of miR‐145‐5p in ALI through the downstream E26 transformation‐specific proto‐oncogene 2 (ETS2)/transforming growth factor β1 (TGF‐β1)/Smad pathway. A lipopolysaccharide (LPS)‐induced ALI rat model was established. The expression of miR‐145‐5p in ALI rat lung tissues was up‐regulated. Afterward, pathological damage in the lung tissue, the wet/dry (W/D) ratio, apoptosis, and serum inflammatory factor contents were observed. miR‐145‐5p, ETS2, TGF‐β1, Smad2/3, and phosphorylated Smad2/3 levels were measured in rats. miR‐145‐5p expression was down‐regulated, ETS2 expression was up‐regulated, and the TGF‐β1/Smad pathway was activated in LPS‐exposed rats. Overexpression of miR‐145‐5p inactivated the TGF‐β1/Smad pathway and attenuated ALI, as reflected by relieved pathological damage, a decreased W/D ratio, reduced apoptosis, and suppressed inflammatory response. In contrast, loss of miR‐145‐5p or elevated ETS2 levels worsened ALI and activated the TGF‐β1/Smad pathway. Moreover, elevation of ETS2 diminished miR‐145‐5p‐mediated protection against ALI. Evidently, miR‐145‐5p negatively regulates ETS2 expression and inactivates the TGF‐β1/Smad pathway to ameliorate ALI in rats.

Human retinal pigment epithelial (RPE) cell cultures are usually obtained from donor eyes; isolation and culture of RPE cells obtained by evisceration has not been reported previously. The present study attempted to isolate and cultivate RPE cells from evisceration specimens obtained from two cases with severe ocular trauma. Two different isolation methods, explantation and enzymatic dissociation, were used. In Case 1, RPE cells grew from the explants, but were contaminated with other cells such as fibroblasts and melanocytes, and no pure RPE cultures were obtained by explantation. In Case 2, RPE cells were separated from choroids using 0.25% trypsin before plating for culture, which effectively eliminated contaminating cells. A pure RPE culture was obtained and cultured with F12 medium supplemented with 30% fetal bovine serum. With this enzymatic dissociation method, cultured RPE cells grew to confluence in primary culture and could be maintained in culture for five passages. Cultured RPE cells were identified by the presence of cytokeratin expression, as shown by immunocytochemical staining. These isolation and culture methods provide alternative sources for human RPE cells and could be useful in studies of the cell biology and pathophysiology of human RPE cells.