Pharmacologic targeting of renal ischemia-reperfusion injury using a normothermic machine perfusion platform.

Normothermic machine perfusion (NMP) is an emerging modality for kidney preservation prior to transplantation. NMP may allow directed pharmacomodulation of renal ischemia-reperfusion injury (IRI) without the need for systemic donor/recipient therapies. Three proven anti-IRI agents not in widespread clinical use, CD47-blocking antibody (αCD47Ab), soluble complement receptor 1 (sCR1), and recombinant thrombomodulin (rTM), were compared in a murine model of kidney IRI. The most effective agent was then utilized in a custom NMP circuit for the treatment of isolated porcine kidneys, ascertaining the impact of the drug on perfusion and IRI-related parameters. αCD47Ab conferred the greatest protection against IRI in mice after 24 hours. αCD47Ab was therefore chosen as the candidate agent for addition to the NMP circuit. CD47 receptor binding was demonstrated by immunofluorescence. Renal perfusion/flow improved with CD47 blockade, with a corresponding reduction in oxidative stress and histologic damage compared to untreated NMP kidneys. Tubular and glomerular functional parameters were not significantly impacted by αCD47Ab treatment during NMP. In a murine renal IRI model, αCD47Ab was confirmed as a superior anti-IRI agent compared to therapies targeting other pathways. NMP enabled effective, direct delivery of this drug to porcine kidneys, although further efficacy needs to be proven in the transplantation setting.

Brief Normothermic Machine Perfusion Rejuvenates Discarded Human Kidneys.

Normothermic machine perfusion (NMP) may allow resuscitation and improved assessment of kidneys before transplantation. Using discarded human kidneys, we investigated the mechanistic basis and translational potential of NMP compared with cold static storage (CS). METHODS: Discarded deceased donor kidneys (n = 15) underwent 1-hour NMP following CS. Renal perfusion, biochemical, and histologic parameters were recorded. NMP was directly compared with CS in paired donor kidneys using simulated transplantation with allogeneic whole blood, followed by assessment of the aforementioned parameters, in addition to RNA sequencing. RESULTS: Kidneys were successfully perfused, with improved renal blood flows and resistance over the course of perfusion, and evidence of urine output (median 21 mL), in all but one kidney. NMP completely resolved nonperfused regions in discarded donation after circulatory death kidneys. In paired kidneys (n = 4 pairs), transcriptomic analyses showed induction of stress and inflammatory pathways in NMP kidneys, with upregulation of pathways promoting cell survival and proliferation. Furthermore, the NMP pairs had significantly better renal perfusion (1.5-2 fold improvement) and functional parameters, and amelioration of cell death, oxidative stress, and complement activation. CONCLUSIONS: In this pilot preclinical study using simulated transplantation of paired kidneys, NMP of discarded marginal kidneys demonstrated some significant mechanistic benefits in comparison to CS alone. NMP may have potential to reduce organ discards and enhance early graft function in such kidneys.

Extra-corporeal normothermic machine perfusion of the porcine kidney: working towards future utilization in Australasia.

BACKGROUND: The ongoing supply-demand gap with respect to donor kidneys for transplantation necessitates the increased use of higher kidney donor profile index and/or donation after circulatory death (DCD) kidneys. Machine perfusion (MP) preservation has become increasingly popular as a means to preserve such organs. Human data regarding normothermic kidney MP (NMP) is in its infancy, and such a system has not been established in the Australasian clinical setting. METHODS: Modified cardio-pulmonary bypass technology was utilized to develop a viable NMP kidney perfusion system using a porcine DCD model. System development and optimization occurred in two stages, with system components added in each experiment to identify optimal perfusion conditions. RESULTS: Device functionality was demonstrated by the successful perfusion of and urine production by, eight porcine kidneys. Urine production diminished in the presence of colloid in the perfusate. Pressure-controlled (compared with flow-controlled) perfusion is preferable as a safe perfusion pressure range can be maintained. More physiologic perfusion conditions are achieved if oxygenation is provided by an oxygen/carbon dioxide mixture compared to 100% oxygen. CONCLUSION: A viable and reproducible NMP system was established and tested in porcine kidneys, which was able to simulate graft function extra-corporeally. Further work is required to identify the most optimal perfusion conditions. Prior to its utilization in clinical transplantation, the system should be tested in non-transplanted human kidneys.