Murine models of renal ischaemia reperfusion injury: An opportunity for refinement using non-invasive monitoring methods

Abstract

BackgroundRenal Ischaemia Reperfusion Injury (R-IRI) can cause Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD), resulting in significant morbidity and mortality. To understand the underlying mechanisms, reproducible small-animal models of AKI and CKD are needed. We describe here how innovative technologies for measuring kidney function non-invasively in small rodents allowed successful refinement of the R-IRI models, and enabled the transition from AKI to CKD to be monitored longitudinally in individual animals. MethodsMale BALB/c mice underwent bilateral renal pedicle clamping (AKI) or unilateral renal pedicle clamping with delayed contralateral nephrectomy (CKD) under isoflurane anaesthetic. Transdermal GFR monitoring and multi-spectral optoacoustic tomography in combination with statistical analysis were used to identify and standardise variables within these models. ResultsPre-clamping anaesthetic time was one of the most important predictors of AKI severity after R-IRI. Standardising pre-clamping time resulted in a more predictably severe AKI model. In the CKD model, initial improvement in renal function was seen, followed by significant progressive reduction in function between weeks 2 and 4. Performing contralateral nephrectomy on day 14 enabled the development of CKD in a survivable way.Conclusions Non-invasive monitoring of global and individual renal function after R-IRI is feasible, reproducible and correlates well with classical markers of injury. This facilitates refinement of kidney injury models and enables the degree of injury seen in pre-clinical models to be translated to those seen in the clinical setting. Thus, future therapies can be tested in a clinically relevant, non-invasive, manner.

Quantifying acute kidney injury in an Ischaemia-Reperfusion Injury mouse model using deep-learning-based semantic segmentation in histology

“…The mouse model of renal IRI was induced by bilateral clamping of the renal pedicle using a dorsal approach. Male mice (9–10weeks) were anaesthetised (isoflurane 1.5%; 1.0 L/min, O 2 ) for 30 min prior to the surgical procedure ( Harwood et al, 2019 ). The body temperature was controlled at 36.5–37.1°C with a homeothermic monitor system (PhysioSuite, Kent Scientific, Torrington), and the renal pedicle was carefully dissected and clamped with a non-traumatic vascular clamp (InterFocus Ltd, Liton, 18052-03) for 27.5 min.…”