The effect of luminal preservation on autophagy and apoptosis during the static cold storage of rat intestines

Introduction: Intestinal transplantation still faces difficulties due to cold ischemia and reperfusion injury. Luminal preservation with PEG-solution has been shown to alleviate ischemic injury compared to cold storage in standard solutions. Autophagy is a cellular mechanism that removes dysfunctional cellular components to maintain homeostasis. Autophagy selectively removes damaged, potentially apoptosis-inducing mitochondria or other organelles and ultimately increases the threshold of stress required for the induction of cell death. Incomplete or failed autophagy may result in apoptosis or necrosis. Studying the activity of autophagy and apoptosis during the ischemic process helps us understand how to minimize the ischemic injury occurring during intestinal preservation. Materials and Methods: Sprague-Dawley rats were used as donors. Intestines were perfused and stored in IGL-1, with and without luminal PEG-3350 solution. Intestinal samples were obtained before preservation and after 8h and 14h of storage. Graft histology (Chiu score, morphometric analysis), immunohistology, and western blot were performed. Autophagy activity was studied by anti-p65 and anti-LC3AB antibodies and apoptosis by studying caspase 3, caspase 9 and Beclin-1. Results: Apoptotic activity seemed to increase at 8h and peak at 14h, although no clear significance was seen on intestines undergoing luminal preservation. Autophagy activity showed a similar pattern, but the intestines receiving additional luminal preservation appeared to have less activity compared to the control intestines (only vascular perfusion). Conclusion: These results confirm apoptosis as one of the ongoing mechanisms during cold intestinal preservation. Apoptotic activity increases during the cold ischemia time, but luminal preservation with PEG seems to decrease it. Autophagy also increases during cold ischemia but the effect of luminal preservation is less clearly delineated.Figure 1.: Graphs show apoptotic and autophagy markers studied with western blot from 0 hours of cold ischemia to 8 and 14 hours with and without luminal preservation with PEG-3350 solution. Y-axis show optical density.