Mihai Oltean^1,2, Catalin Ciuce², Michael Olausson¹, Meghnad Joshi², Gustaf Herlenius¹

¹Sahlgrenska Transplant Institute, Sahlgrenska University Hospital, Gothenburg, Sweden; ²Transplant Biology Laboratory, University of Gothenburg, Gothenburg, Sweden

Luminal introduction of various customized solutions containing aminoacids, macromolecules or perfluorocarbon alleviates the preservation injury through various putative mechanisms. Energy depletion during the cold storage is considered a major cause behind the intestinal preservation injury. We tested if the addition of two main energy substrates, glucose (GLU) and glutamine (GLN) influence the development of preservation injury.

Rat intestines were perfused with UW solution and stored for 8, 14 and 20 hours. A polyethylene glycol (PEG)-3350 based solution was introduced intraluminally, with or without GLN (20 mmol/L) or GLU (5 mmol/L).  Preservation injury was evaluated considering the intestinal morphology (Park scale) and maltase activity. ZO-1 and claudin-3 were studied using immunofluorescence.

After 8h preservation, intestines undergoing UW perfusion alone revealed significant subepithelial edema (Park grade 3) that later progressed until complete mucosal disruption (grade 6-7 at 20h).  Intestines receiving PEG solution showed moderate edema (grade 2) at 8h but advanced mucosal injury (grade 6) at 20h. Intraluminal PEG-GLN solution significantly improved morphology (normal or discrete subepithelial edema edema at 8h (grade 1-2) and continued to have preserved, continuous mucosa even after 20h. In contrast, PEG-GLU intestines did worse than any the other group including UW alone at all time-points. Maltase activity decreased about 33% during preservation, similar in both groups.  Progressive ZO-1 and claudin-3 delocalization was found in all groups, most significant in intestines receiving intraluminal GLU.

Intraluminal glutamine greatly improved intestinal preservation and stabilized the tight junction complex. Luminal glucose did not affect brush-border enzymes but worsened the preservation injury. A possible mechanism may be an increased intracellular sodium inflow (glucose/sodium co-transport) that may have triggered cytoskeleton contraction, TJ dysfunction and epithelial breakdown.