407.1: Experimental Assay of Intestinal Graft Viability and Function After Regional Abdominal Normothermic Perfusion

Abstract

Introduction: DCD has not been considered as a valid alternative for intestinal transplantation (IT). However, normothermia has recently improved the results of the classic cold perfusion in other organs. Our aim was double: to test the viability and function of the intestinal grafts using normothermic regional perfusion (NRP) in an experimental porcine model and to assess ischemic-reperfusion injury (IRI) of the small bowel in human DCD. Method: We used 8 donor-recipient pairs (25.5 ± 2.5 kg), supporting donors with an abdominal NRP. Their small intestine was heterotopically transplanted into the recipients. Blood and intestinal samples were obtained repeatedly throughout the procedure and 1, 2, 7 and 14 days after. IRI was evaluated using Park-Chiu score (PCS) in samples taken during NRP and up to 48 hours after IT. Samples from 7 and 14 days were analyzed to assess graft rejection and GVHD. The gene expression for TJP1, EPCAM, MUC2, LYZ, IL-6, and TNF was measured in all samples. The absorptive function of the grafts was tested at the endpoint. Glycemia from the draining veins of the graft was compared with that from the native small bowel and peripheral blood 15, 30 and 60 minutes after intra-graft glucose administration. The small intestines from eight human DCDs were also sampled for histological analysis while other organs were procured for transplantation. Results: All the intestines were successfully procured. One case was excluded due to venous stenosis. 6 animals (86%) reached the endpoint in good conditions. Grafts conserved architecture during NRP. The highest PCS was observed 1 hour after reperfusion, with denuded villi (PCS-4) in 3 samples (43%). All grafts recovered, with no or very subtle alterations after 48 hours. Five recipients (71%) did not show rejection signs at any time. 2 cases expressed mild rejection (29%) after 7 days. At the endpoint, one of them had recovered but the other had progressed to severe acute cellular rejection (14%). TNF-α, TJP-1 and IL-6 showed maximum levels at the endpoint. Grafts’ glycemia reached its maximum 30 minutes after glucose administration, demostrating their absorption capacity. Human samples did not show any IRI in 80% of the cases. Conclusion: This experimental model postulate DCD with NRP as an alternative source of organs to address the mismatch between the waiting list for IT and the scarcity of donors. Its clinical and functional results appear to be comparable to those of other procurement techniques. The analysis of the human samples suggests that this approach could be successfully translated to the clinical setting. The authors thank NUPA (Spanish Association of Help to Children and Adults with Intestinal Failure, Parenteral Nutrition and Multivisceral Transplant) and Fundación Mutua Madrileña for their support of the present research.