Compared with Static Cold Storage, Hypothermic Machine Perfusion Mitigates Oxidative Stress and Tubular Injury in Rat Kidneys

Background: Hypothermic machine perfusion (HMP) has been shown to lower the incidence of delayed graft function compared to static cold storage (SCS) in kidney transplantation. However, the molecular changes induced by cold storage (CS) between these two preservation methods are not well understood. Methods: In this study, we used a Lewis rat model to compare the molecular effects of HMP and SCS on kidneys prior to transplantation. Both kidneys were flushed with cold saline (4°C) followed by preservation of the left kidney by HMP (at constant pressure with Belzer’s machine perfusion solution), and the right kidney stored via SCS using University of Wisconsin solution—both for 4 hours at 4°C. Results: To assess mitochondrial function, we analyzed respiratory complex activity in fresh kidney biopsies. While no significant difference in respiratory activity was observed between the two groups, Western blot analysis revealed a marked increase in NDUFS3 (a subunit of mitochondrial complex I) in HMP-preserved kidneys compared to both SCS and control kidneys. Immunohistochemical staining showed that kidneys preserved by SCS had higher levels of oxidative stress (nitrotyrosine) and injury markers (KIM-1 and NGAL), whereas HMP significantly reduced the expression of these proteins. Conclusion: Taken together, these findings suggest that compared to SCS, HMP may better protect kidneys from oxidative stress and injury during cold preservation. Future studies should explore longer preservation times and post-transplant outcomes to further evaluate the benefits of HMP in rat kidney transplantation. Funding: R01DK123264 (Parajuli). Funding: NIDDK Support