Nano-Self-Assembled Particles Loaded with Aldehyde Dehydrogenase 2 Agonist Inhibit Ischemia-Reperfusion Injury of Transplanted Kidneys

Kidney transplantation serves as an ideal treatment for patients with end-stage renal disease. Due to the organ shortage, there has been an uptick in the use of circulatory death donors (DCD), yet DCD kidneys endure severe ischemia-reperfusion injury (IRI), limiting transplantation efficacy. Therefore, we developed a strategy combining hypothermic machine perfusion (HMP) with aldehyde dehydrogenase 2 (ALDH2) agonist Alda-1, using quaternized chitosan/5β-cholanic acid/Alda-1 nanoparticles (A-NCH) for ex vivo DCD kidney repair. Methodologically, A-NCH was synthesized by conjugating O-hydroxypropyl trimethylammonium chloride chitosan (O-HTCC) with 5β-cholanic acid via EDC/NHS-mediated coupling, forming self-assembled micelles with a mean diameter of 132.4 ± 0.3 nm and ζ-potential of 45.0 ± 1.0 mV. It exhibited a high drug loading ratio (41.9%), with 80% of Alda-1 released at 4 °C within 3.5 h following the Weibull model, enabling sustained drug delivery during HMP. A-NCH demonstrated outstanding compatibility with cells and blood, as well as effective antibacterial properties combat Escherichia coli and Staphylococcus aureus. In vitro, A-NCH reduced H₂O₂- and oxygen-glucose deprivation- and -reoxygenation-induced oxidative stress and apoptosis in HK-2 and HUVECs. In vivo, using a rat DCD kidney transplantation model, A-NCH-administered HMP accelerated kidney graft function recovery and alleviated renal tubular injury. Mechanistically, A-NCH activated ALDH2, inhibited the P38 MAPK pathway, promoted nuclear translocation of TEAD4/YAP1, and suppressed the transition of proximal tubule cells to an injured phenotype. In this study, the solubility and drug loading of Alda-1 were improved by 5β-cholanic acid modification of O-HTCC, which proved the synergistic efficacy with HMP in DCD kidney repair and provided a translatable strategy to expand the donor pool.