A Novel Rodent Hybrid Model of Renal Ischemia Reperfusion Injury/Autotransplantation.

Abstract

Introduction: Ischaemia reperfusion injury (IRI) is major cause of acute kidney injury and allograft dysfunction. No evidence-based protective or restorative treatments are in widespread clinical use. This reflects the limitations of current in-vivo models, which cannot mimic the severity of IRI observed clinically, without excessive post-procedure animal deaths from acute renal failure. Stem cell-based therapies may protect against IRI and aid regeneration of damaged tissues. However, systemic drug delivery methods lead to side-effects that limit dosing and produce sub-optimal drug concentrations in the key tissues. Serum markers commonly tested lack the sensitivity to demonstrate quantitative changes in renal function in response to injury +/- therapeutic intervention. Methods: In a novel rat model of severe left renal IRI the left renal artery is clamped and transected. The kidney is perfused via intra-renal artery infusion of therapeutic agents or vehicle. After arterial anastomosis, clamps removed to provide 120 mins of warm ischaemia. The right kidney remains to prevent death from acute renal failure. Animals are recovered for a 2 or 6 week period before terminal GFR studies by inulin clearance. Each ureter is cannulated to allow the GFR of kidney to be calculated separately. Kidneys are analysed for histology, and molecular markers of damage. Results: Compared to sham operations, saline treated animals suffer a long-term reduction in GFR of around 40%, with associated histological, and molecular markers of injury. Anastomotic patency rates approach 100%. Despite the injury severity, post-operative animal losses are <5%. Conclusion: Using this model, we are able to inflict a severe, consistent renal injury. Intra-renal artery infusion allows a high local concentration of therapy without systemic distribution, minimising total drug amounts administered, reducing side effects. This mimics the route most likely employed in clinical transplantation, where the renal artery is accessible. Inulin clearance most accurately characterizes GFR, allowing full assessment of therapeutic intervention. This model is a useful tool for screening potential therapeutic agents, prior to testing in a more complex uraemic or transplant model. This reduces animal numbers needed to test drugs for clinical transplantation and allows for refinement of dosing schedules.