Mitigation of Ischemia-Reperfusion Injury and Improvement in Overall Graft Viability by Hypothermic Pulsatile Perfusion with Molecular Hydrogen Is Associated with Trx-1/HO-1 Activation in a Non-Survival Ex Vivo Swine Model of Donation-After-Circulatory-Death Kidney Preservation and Transplantation

Despite their reduced viability, kidneys from donors-after-circulatory-death (DCD) increase the pool of transplantable kidneys. Molecular hydrogen (H2) is emerging as a gas with therapeutic potential against graft injury. We investigated the effect of H2 in an ex vivo porcine model of DCD kidney transplantation. Renal arteries of male Yorkshire pigs (n = 6) were clamped in situ for 60 min to induce ischemia, and ureters and arteries were cannulated to mimic DCD kidney injury. Upon nephrectomy, kidneys were flushed with UW solution or H2-saturated UW solution and then preserved by machine perfusion at 4 °C for 4 h followed by a 4-h reperfusion period with warm autologous blood. Urine and arterial blood samples were collected hourly. H2 preserved renal architecture, evidenced by significantly reduced tubular necrosis and renal expression of damage markers, which corresponded with the downregulated renal expression of pro-inflammatory genes compared to the UW-only group (p < 0.05). H2 also markedly reduced levels of serum creatinine, BUN and intrarenal resistance, while flow rate, creatinine clearance and urine output were significantly higher, which positively correlated with Trx-1 and HO-1 expression in comparison with UW only group (p < 0.05). Improvement in renal graft quality and function is associated with Trx-1/HO-1 activation, suggesting preliminary clinical trials in kidney transplantation.