A. Bertacco1, A. Alkukhun1, R. Agarwal1, C. P. LeBlanc1, A. Munoz-Abraham1, F. D’Amico1, M. Rodriguez-Davalos1, J. Geibel1 1Yale School Of Medicine,Surgery/Transplantation,New Haven, CT, USA
Introduction: Prevention of intestinal ischemia during small intestine transplantation still remains a challenge . A safe and effective preservation solution is a precondition for successful small intestine transplantation. The most commonly used hypothermic preservation solutions for intestinal transplantation are the University of Wisconsin solution (UW) and histidine-tryptophan-ketoglutarate (HTK). We have previously shown that intestinal ischemia results in an increased fluid shift towards the lumen of the intestine. In the present study we demonstrate that as the temperature increases (4-37 C) the HTK becomes more acidic. Using this knowledge, our aim was to evaluate the effect of the UW and HTK solution on the viability of an intestinal preparation at normothermic temperature in a rat perfusion model.
Methods: Male Sprague Dawley rats (average weight 440g) were anesthetized and euthanized in accordance with the Animal Care and Use Committee at Yale University. Two sequential small intestinal segments were procured and flushed with regular HEPES solution (with a pH 7.40, mOsm 300 at 37 C) to remove any remaining intestinal debris. The intestines were then connected to our intestinal chambers, which allowed both luminal and extraluminal perfusion. The first intestine was filled intraluminally with 1.5ml of UW Solution including 50µM of FITC-Inulin, and was surrounded by standard UW solution on the vascular side. The second intestine was filled with 1.5ml of HTK Solution including 50µM of FITC-Inulin, and was surrounded by HTK solution on the vascular side. Both chambers were maintained at 37o C. Sample measurements of intraluminal perfusate were made to measure FITC-Inulin concentration, using the Nanodrop 3300™and were taken at times 0,45,90 and 120 minutes.
Results: When comparing the FITC-Inulin concentration in both intestines, there was a mean reduction of 43.25% of FITC-Inulin concentration in the UW arm vs a 9.5% decrease in the HTK arm, indicating more fluid secretion in the intestine exposed to UW.
Conclusion: We have shown that UW solution increases the fluid shift towards the lumen at normothermic temperature compared to HTK solution. Surprisingly, we did not observe the expected amount of secretion from the acidic HTK. With that response, we recognized that UW is a better preservation solution at 37 C due to either it’s buffering capacity in the intestinal lumen, or starch component present in it’s composition. We hypothesize that UW results in decreased cellular swelling in the small intestine cells at normothermic conditions, and thus could leed to a a better outcome for intestinal preservation at normothermic temperatures.