The endoplasmic reticulum (ER) represents a subcellular target reactive to various cytosolic impairments. The involvement of ER-stress in organ preservation was investigated, comparing machine preservation, cold storage (CS) and a novel concept of only temporary perfusion after procurement. Rat livers were retrieved 30 min after cardiac arrest and preserved for 18 h by CS, oxygenated machine perfusion for 18 h (18 h MP) or for 2 h with subsequent CS for 16 h (2 h MP + 16 h CS). Upon reperfusion, 18 h MP significantly improved enzyme leakage (ALT, LDH) and promoted a 2-fold increase of metabolic recovery compared to CS. However, vascular stress, evaluated by endothelinrelease, was significantly elevated after 18 h MP. Interestingly, better viability was obtained using the shortterm perfusion protocol (2 h MP + 16 h CS), which further reduced enzyme leakage, maintained energetic recovery and mitigated endothelin-release compared to 18 h MP. Caspase 12-mRNA was upregulated in the 18 h MP-group but unchanged after CS or 2 h MP + 16 h CS. Activation/cleavage of caspase 12 protein was significantly enhanced after 18 h MP and very low in the 2 h MP + 16 h CS-group. Correspondingly, electron microscopy showed ultrastructural alterations of ER after CS and especially after 18 h MP but not after 2 h MP + 16 h CS. At this time mitochondrial appearance was unaffected in all groups, suggesting the ER to be an early subcellular target of preservation injury. In our model, ER and vascular endothelium were best protected by only temporary machine perfusion, which also maintained overall graft viability.

The increasing interest in neoadjuvant chemotherapy of liver metastasis after colorectal carcinoma prior to resection has focussed surgical concerns to the influence of oncological chemotherapy on hepatic tolerance to intraoperative ischaemia. The present study was thus undertaken in order to produce first experimental data on liver function and morphology after neoadjuvant chemotherapy and subsequent ischaemic challenge in a rat model. Male Wistar rats were randomised to receive an intraperitoneal chemotherapy (CH) or placebo (PL) according to the same protocol. Afterwards the animals were subjected to 30 min of total hepatic ischaemia induced by Pringle's manoeuvre and subsequent reperfusion for 1 h or 24 h. Serum activities of hepatic enzymes showed no differences between CH and PL at any time. Bile flow, however, was found to be significantly reduced in CH. In contrast, post-ischaemic up-regulation of PUMA and cleavage of caspase3 was found to be more prominent in PL than in CH, while the antiapoptotic chaperone GRP78 revealed a higher expression in the latter. It is concluded that chemotherapy did not affect ischaemic tolerance of the liver in our model, but promoted a kind of preconditioning, that is likely to counteract cellular induction of apoptosis upon ischaemic challenge.

Background Active MMP-9 disruption of the extracellular matrix plays an important role in inflammatory disorders. In this study, we investigated the inflammatory role of MMP-9 and the extracellular matrix (ECM) breakdown product hyaluronan as a trigger for the postoperative intestinal inflammatory response of postoperative ileus. Methods A standardized intestinal surgical manipulation (SM) was performed on rats to produce ileus assessed by the oral non-digestible FITC-dextran transit assay. Isolated intestinal muscularis extracts were studied for mRNA expressions of IL-6, MMP-9 and CD44. Peritoneal MMP-9 activity was quantified using zymography. Peritoneal fluid and serum were quantified for hyaluronan and TIMP-1 levels by ELISA. Peritoneal macrophages were cultured and exposed to peritoneal fluid or synthetic hyaluronan for ELISA analysis of IL-6 and MIP-1α. Results Transit was significantly delayed after SM and extracts of the isolated jejunal and colonic muscularis demonstrated a significant induction of IL-6, MMP-9 and CD44 mRNAs compared to controls. Zymography confirmed significant MMP-9 activity in peritoneal fluid compared to controls. ELISA measurements showed a significant upregulation in hyaluronan and TIMP-1 in the peritoneal fluid and serum. Additionally, ELISA and RT-PCR measurements of peritoneal macrophages stimulated with postsurgical peritoneal fluid and synthetic hyaluronan resulted in higher expressions of IL-6 and MIP-1α in the macrophage supernatant. Conclusions Our results confirm that MMP-9 disruption in the ECM with hyaluronan release and muscularis CD44 receptor induction has the potential to trigger muscularis proinflammatory cascades which cause postoperative ileus and we suggest that MMP-9 inhibition may be a novel therapeutic approach to limit postoperative ileus.

It is concluded that CH leads to a delay in liver regeneration but is no contraindication for ischemia. On the contrary, CH seems to cause a preconditioning of livers leading to the induction of antiapoptotic chaperones in our short-term model.