Microarray-based clustering analysis of miRNAs altered in IRI-AKI mouse kidney

The aim of this study was to identify miRNAs that regulate AKI and develop their applications as diagnostic biomarkers and therapeutic agents. First, kidney tissues from two different AKI mouse models, namely, AKI induced by the administration of lipopolysaccharide (LPS) causing sepsis (LPS-AKI mice) and AKI induced by renal ischemia–reperfusion injury (IRI-AKI mice), were exhaustively screened for their changes of miRNA expression compared with that of control mice by microarray analysis. A model with ischemia–reperfusion injury-induced acute kidney injury (IRI-AKI) was created in accordance with a previously reported method. This IRI model was generated using male C57BL/6 mice (9 weeks old; 20–25 g) housed in a room with controlled temperature, humidity, and a 12 h light–dark cycle. The mice were anesthetized using isoflurane as follows: anesthesia induction concentration 3.0%–5.0%, maintenance concentration 2.0%–3.0%, and concentration during clamping 1.0%–1.5%. In the IRI model described here, single midline abdominal surgery was used both to perform right nephrectomy and to induce ischemia–reperfusion of the left kidney. Successful ischemia could be visually confirmed by gradual uniform darkening of the kidney. This IRI model had a 25- or 45-min clamping time, with the kidneys being collected 12 or 24 h later. A blood sample was obtained from the vena cava of each animal. For the sham model of IRI, only a midline incision was made.