Renal ischemia-reperfusion injury is inevitable in the course of kidney transplantation and can lead to delayed graft function, graft failure, increased postoperative morbidity, and mortality. Relaxin, an insulin-related peptide hormone, protects against renal ischemia-reperfusion injury in rodent models. Although it has yet to be tested in clinical settings given lack of large animal studies. Thus, this study was designed to investigate the effect of Relaxin supplemented to Custodiol® for static cold storage in a large animal kidney transplantation model. In this blinded, randomized, and placebo-controlled experimental study, kidneys from 19 donor pigs were retrieved after perfusion with Custodiol® supplemented with Relaxin (5 or 20 nmol/l) or placebo. Right and left kidneys underwent static cold storage for 24 or 48 hours, respectively. Kidney samples were harvested for PCR analysis to investigate oxidative stress. Apoptosis/necroptosis-related gene panels and immunohistochemistry were performed to document apoptosis and oxidative stress-induced cell damage. Subsequently, kidneys were transplanted after unilateral right nephrectomy, and recipients were followed up for 28 days. Blood biochemistry markers for kidney function, including indicators of oxidative stress, lipid peroxidation, and endothelial cell damage (Carbonyl protein; Malondialdehyde; 4-hydroxynonenal; Myeloperoxidase; Big Endothelin; and Total Oxidant Status) were determined. The results of the study showed that perfusion with Relaxin upregulated SOD2 and NFKB gene expression to 135 % (p=0.042) and 125 % (p=0.019), respectively. At the same time, RIPK1 expression was downregulated to 82 % (p=0.016) of corresponding controls. Furthermore, after static cold storage, Relaxin significantly downregulated RIPK1 and MLKL expression and decreased the number of Caspase 3- and MPO-positive cells in kidney grafts. This is the first large animal study demonstrating that ischemic injury was significantly diminished after static cold storage in Custodiol® supplemented with Relaxin via both antioxidant and anti-apoptotic/anti-necroptotic mechanisms. Clinical trials are warranted to implement synthetic human Relaxin as a novel additive to preservation solutions to combat ischemia-reperfusion injury in kidney transplantation.
Relaxin in organ preservation: a large animal study
Baušys, A. (Author). 2022
Student thesis: Doctoral thesis