Protective Effect of PEG 35 000 Da on Renal Cells: Paradoxical Activation of JNK Signaling Pathway During Cold Storage

Abstract

Polyethylene glycol (PEG), a high-molecular weight colloid, is added to preservation solutions in order to decrease cold-and ischemia-induced injuries of the grafted organ. We evaluated on LLC-PK1, a porcine proximal tubular epithelial cell line (1) the efficiency of several commercial preservation solutions (University of Wisconsin, Euro-Collins, Celsior, SCOT, IGL-1), and (2) whether adding PEG (400-35 000 Da) in a simple extracellular-type buffer modified cell integrity and mitogen-activated protein kinase (MAPK) signaling pathways. SCOT was the most efficient commercial solution. Moreover, only PEG 35 000 Da totally preserved cell viability, induced a decrease on reactive oxygen species production and a decrease on p38-MAPK activation. Furthermore PEG 35 000 Da stimulated c-Jun N-terminal kinase (JNK). However, the inhibition of JNK pathway, with the specific SP600125 inhibitor, in the presence of PEG 35 000 Da did not affect cell survival. We also confirmed on whole pig kidney the protective effect of PEG 35 000 Da on cold-induced tubular injuries. This study confirms PEG antioxidative properties, but we demonstrate that its effect on JNK signaling pathway had also a paradoxical effect on cell death. This sheds a new light on PEG effects during cell preservation, independently from the classical immuno-camouflaging hypothesis.

Polyethylene glycols interact with membrane glycerophospholipids: is this part of their mechanism for hypothermic graft protection?

“…The presence of 1 g/L of PEG35000 stabilized the DPPC monolayer in the gaseous phase more strongly than PEG20000. This could be in agreement with the higher effectiveness of PEG35000 against cold-induced injuries observed in our cellular preservation model and also with the higher protection of PEG35000 observed during organ transplantation [3,4,11].…”

“…We have previously shown in our in vitro model of coldpreservation that the storage of LLC-PK1 cells during 24 h at 4°C in EC was very deleterious inducing more than 80% of cell death [11]. Adding only 1 g/L of PEG35000 in the preservation solution protected cells against cold-induced injury, decreasing the LDH release by around 20%.…”

“…We previously demonstrated that PEG present in an extracellular type solution protected, to some extent, cultured renal epithelial cells against damages caused by hypothermia and that the different PEGs tested from 400 to 20,000 Da reduced the cold-induced cell death by 50% [11]. Only PEG35000 was able to protect totally against necrosis.…”

Cold Preservation Mediated Renal Injury: Involvement of Mitochondrial Oxidative Stress

“…Cells exposed to cold storage have been shown to sustain mitochondrial injury and cell death. [14,17,34,36] Our data using a novel rodent model of short-term cold renal preservation demonstrate that cold I/R induces significant renal injury that is accompanied by elevations in oxidant production and mitochondrial dysfunction. This appears to be the first report showing that minimal cold preservation (i.e., 40 minutes) in vivo results in early renal and mitochondrial dysfunction.…”

Evaluation of Institut Georges Lopez-1 Preservation Solution in Pig Pancreas Transplantation

“…PEG35 is a highYmolecular weight polymer, nontoxic, and water soluble, with properties of particular interest in organ preservation (18), including exerting an oncotic pressure that reduces the deleterious effects of edema (19). PEG is absorbed on the surface of cell membranes, preserves or restores the integrity of plasma membranes, and reduces lipid peroxidation (LPO) (14,16,18,20,21).…”