Influence of Hypothermic Machine Perfusion on Markers of Oxidative Stress and Early Tubular Injury in Rat Donor Kidneys Before Transplantation

Background: Hypothermic machine perfusion (HMP) has been associated with reduced delayed graft function compared with static cold storage (SCS). However, the molecular mechanisms underlying these differences during cold preservation remain incompletely understood. This study compared cold-storage-related biochemical and histological changes in kidneys preserved by HMP versus SCS using a Lewis rat model prior to transplantation. Methods: Following isolation, rat kidneys were flushed with cold saline (4 °C). Left kidneys were preserved by HMP at constant flow using Belzer’s machine perfusion solution (MPS) at 4 °C, while right kidneys were stored using SCS in University of Wisconsin solution at 4 °C. After four hours of preservation, kidneys were processed for biochemical and histological analysis. Fresh biopsies were evaluated for mitochondrial complex respiration. Western blotting was performed to assess expression of NDUFS3, a complex I subunit. Histological staining for nitrotyrosine and kidney injury markers was compared across groups. Results: Mitochondrial complex respiration did not differ significantly between the SCS and HMP groups. Western blot analysis demonstrated significantly increased NDUFS3 expression in HMP-preserved kidneys compared with SCS and control kidneys. Histological evaluation revealed elevated tubular staining of nitrotyrosine and kidney injury markers in SCS kidneys relative to controls, whereas HMP preservation markedly attenuated these increases. Conclusions: HMP mitigates cold-storage-induced oxidative stress and reduces expression of kidney injury markers after four hours of preservation. These molecular findings suggest a protective effect of HMP during cold preservation. Future studies with longer preservation times and transplantation models are needed to determine whether these improvements translate into enhanced post-transplant kidney function.