Organs obtained from brain dead donors can have suboptimal outcomes. Activation of the innate immune system and translocation of intestinal bacteria could be causative. Thirty two pigs were assigned to control, brain death (BD), BD + luminal intestinal polyethylene glycol (PEG), and BD + luminal intestinal University of Wisconsin solution (UW) groups. Animals were observed for 360 min after BD before organ retrieval. 2,000 mL luminal intestinal preservation solution was instilled into the duodenum at the start of organ procurement. Repeated measurements of plasma C3a, Terminal Complement Complex (TCC), IL-8, TNF, and lipopolysaccharide binding protein were analysed by immunoassays. C3a was significantly higher in the BD groups compared to controls at 480 min after brain death. TCC was significantly higher in BD and BD + UW, but not BD + PEG, compared to controls at 480 min. TNF was significantly higher in the BD group compared to all other groups at 480 min. LPS binding protein increased following BD in all groups except BD + PEG, which at 480 min was significantly lower compared with all other groups. Brain death induced innate immune system activation was decreased by luminal preservation using PEG during organ procurement, possibly due to reduced bacterial translocation.

Background: Organs obtained from brain dead (BD) donors often have worse outcomes. Activation of the complement system and translocation of intestinal bacteria could be causative. We aimed to examine activation of the complement system following BD and evaluate the systemic and local effect of adding luminal intestinal preservation to classical vascular preservation. Methods and material: BD was induced in 30 pigs (four groups: control (n=7), BD alone (n=8), BD + luminal intestinal polyethylene glycol (PEG, n=7) and BD + luminal intestinal University of Wisconsin solution (UW, n=8) using a previously validated method and all animals were observed for 6 hours before organ retrieval. In the PEG and UW groups, 2000 ml of the selected solution was instilled into the duodenum during the organ procurement surgery. Repeated measurements of C3a, Terminal Complement Complex (TCC), IL-8 and TNF were performed in plasma at baseline, BD, 30, 60, 120, 240 and 360 minutes after BD, and following the intestinal intervention (480). Plasma lipopolysaccharide binding protein (LPS-BP) was measured at baseline, BD, and 480 minutes after BD. All were normalised to albumin concentration. Biopsies were taken from jejunum and ileum at time of removal and following 8, 14 and 24 hours of static cold storage (SCS) using UW. Preliminary analysis has been performed at 24 hours of SCS for the BD groups, full histology will be available soon. Results: All animals were kept circulatory- and respiratory stable until organ procurement. At 480 minutes, C3a was significantly higher in BD, BD+PEG, and BD+UW groups compared to control group (all p<0.05) (fig. 1A). TCC was significantly higher in the combined BD group compared to control at 360 minutes, at 480 minutes, the BD and BD+UW groups were significantly higher compared to the control group (all p<0.05) (fig. 1B). IL-8 and TNF were significantly higher in the BD group compared to all other groups at 480 minutes (p=0,003 and p=0.001) (fig. 1C and D). LPS-BP increased following induction of BD in all groups except BD+PEG, which at 480 minutes were significantly lower (p=0.002) (fig. 1E and F) compared with all other groups. Preliminary biopsies from the Jejunum after 24 hours of SCS show a reduced median Chiu/Park score in the BD+PEG (2.5) and BD+UW (2.0) groups compared to the BD group (fig. 2). Conclusion: The complement system is activated following BD independently of intestinal and luminal preservation and may lead to inflammation. Luminal intestinal preservation during organ procurement led to lower Chiu/Park scores, and reduced cytokine and LPS-BP expression, which may be due to reduced bacterial translocation occurring during surgery independent of BD. Luminal PEG intervention may be combined with early innate immune system inhibition in BD donors to prevent systemic inflammation, which hampers organ function.

Background: Intestinal transplantation (ITx) has shown sub-optimal graft survival rates for the last ten years, mostly due to rejection and subsequent sepsis. This could be improved by reducing initial preservation injury. Experimental studies applying luminal preservation (LP) to animal and human intestines show promising results. Herewith presented is the first trial of luminal preservation LP of human intestines from suitable donors in a clinical setting. Methods: Twenty-five bowels (small intestine and ascending colon) from brain-dead donors meeting criteria for ITx (age extended to ≤ 70 years) were divided into four groups in two European centres that use different vascular perfusion solutions (University of Wisconsin, UW, or Institut Georges Lopez-1, IGL-1). Two groups served as controls (only vascular perfusion), two as LP treatment groups with additional ice-cold polyethylene glycol 3350 (PEG). LP occurred before and during vascular perfusion via the existing nasogastric tube, placed manually in the duodenum during procurement. Samples from procurement and after seven and fourteen hours of cold storage were scored histologically for intestinal preservation injury (IPI). Results: Implementation of LP did not prolong procurement times. PEG reached the terminal ileum but did not pass into the large intestine (colonic samples were thus not analysed). LP significantly reduced jejunal mucosal damage at procurement, independently of the vascular flush solution used, compared to control groups (median IPI scores 2 in control groups, 0 in treated groups 0, p < 0.001). LP protected the jejunum during cold storage when IGL-1 was the vascular preservation solution. LP had little effect on the ileum, though a marginally worsened mucosa was observed after seven hours in UW vascular flush group (IPI 3 in both groups, higher range values in treated group, p = 0.01). Conclusion: Luminal preservation with ice-cold PEG is clinically applicable without generating changes in procurement times or techniques. LP reduced jejunal IPI at procurement and during cold storage in vascular IGL-1-preserved intestines, but not after vascular preservation with UW.

Introduction: Graft survival rates in intestinal transplantation (ITx) are the lowest among solid organ transplantation. Unique for ITx is the presence of metabolically-active luminal content consisting of microbes, dietary and waste products. Ischemic damage during cold storage decreases mucosal integrity, which contributes to graft rejection and infections. Cold storage of the bowel is limited to 10 hours, after which it is deemed unsuitable for transplantation. Luminal preservation (LP) with polyethylene glycol (PEG) has shown promising effects in improving graft-viability in experimental animal models. The ITx centres in The Netherlands and Belgium joined forces with the aim to analyse the effect of LP on graft viability. Methods: A prospective study was set up with 4 study groups: 1. Control: University of Wisconsin solution (UW) for vascular perfusion (VP) only 2. VP + LP: UW+PEG 3. Institut Georges Lopez-1 solution (IGL-1) for VP only 4. VP + LP: IGL-1+PEG Inclusion criteria follows recommendations from the Organ Procurement and Transplantation Network for ITx, with extended age to 70 years (due to donor shortage) and no anthropomorphic features taken into account. Donors underwent standard dissection for organ procurement. If LP was included, the intestine was perfused with PEG (6.4% w/v) through the nasogastric tube. Samples were taken at 0, 7 and 14 hours after start of preservation. Analyses include histology (Park/Chiu preservation score), and further studies on gene and protein expression, and bacterial localisation and composition. Results: So far, 9 bowels were included. In Dutch cases (N=7), 4 grafts received VP-only and 3 grafts received LP. In Belgium, 2 VP-only experiments were performed so far. VP-only samples show decay of the intestinal microscopic structure over time with necrosis of villi tips and mucosal disintegration (Figure 1 a, b, c). LP samples show a conserved epithelial lining up to 14 hours of cold storage, with increasing signs of subepithelial oedema (Figure 1 a, d, e). Preservation scores reflect these findings (Figure 2). Conclusion: These preliminary data suggest that LP with PEG reduces preservation injury in intestinal grafts. LP might thus improve graft viability and increase its preservation time-window. Different LP solutions are being tested and further analyses are underway to address barrier function and the cause of the subepithelial oedema.