Establishment of A Mouse Model of Renal Fibrosis via Unilateral Ischemia-Reperfusion Injury And Delayed Contralateral...

Renal ischemia-reperfusion injury (IRI) contributes to acute kidney injury (AKI) and is a major driver of progression to chronic kidney disease (CKD). A reproducible animal model is necessary to facilitate the evaluation of maladaptive repair and fibrosis mechanisms. Herein is reported a standard mouse model of renal fibrosis established by unilateral ischemia-reperfusion injury (uIRI) followed by contralateral nephrectomy (CNx). This strategy ensures long-term animal survival during disease progression while enabling the precise assessment of residual renal function of the injured kidney at the time of harvest. Male C57BL/6 mice were subjected to warm ischemia for 28 min at 37 °C, and a CNx was performed 24 h prior to each study endpoint. Mice were sacrificed for histological and immunohistochemical evaluations at the following time points: 2 days, 5 days, 1 week, 2 weeks, 3 weeks, and 4 weeks post-IRI. On postoperative days 2 and 5, the kidneys primarily exhibited tubular necrosis, particularly at the corticomedullary junction, without evidence of interstitial fibrosis. Starting one week after surgery, these pathological features were replaced by inflammatory cell infiltration and early tubular atrophy; interstitial fibrosis also emerged and reached its peak severity by the second week. During the third and fourth weeks after surgery, the kidneys showed widespread tubular atrophy consistent with disuse atrophy. Notably, interstitial fibrosis was reduced compared to the second week, indicating progression to the quiescent, hypocellular scarring phase. This model effectively reproduces the clinical scenarios of the AKI-to-CKD transition and provides a reliable platform for exploring fibrotic mechanisms and screening therapeutic interventions.