Replacement Of The Portal Vein By The Allograft For Radical Resection Of Pancreatic Carcinoma

BackgroundsThe management of pancreatic and hepatic hilar tumor involved the superior mesenteric and portal vein (SMPV) represents the most challenging technical aspect of biliary-pancreatic surgery. Prior studies have demonstrated that partial or segmental portal vein (PV) resection and reconstruction is an ideal means of managing tumor adherence to the SMPV. A vascular conduit has to be used for reconstruction of the SMPV when the defect after a complete resection fails to be restored by direct anastomosis. Options for conduit during SMPV reconstruction include synthetic or autologous vein, as well as allogeneic vessels. Autologous conduits, such as saphenous vein, superficial femoral vein and renal vein, are extensively adopted for reconstruction. However, harvesting an autograft is associated with increased operating time, and the sacrificingof the major vein is sometimes associated with postoperative edema of the lower leg or impairment of function in poor-risk patients. Greater saphenous vein can be sacrificed with minimal disadvantage but is not suitable to interpose a major vein. The use of PV allografts provided by cadaveric liver transplants was a preferable alternative to autografts, due to its identical anatomical nature and immediate availability for implantation. Some methods like cryopreservation allows ready access to a stored inventory of allografts that are immediately available when the need arises.Rodent models for allogeneic aortic segment transplants, autologous vein interposition have been developed for study transplant vasculopathy and neointimal hyperplasia of venous conduit. To our knowledge, the orthotopic PV graft has not been investigated in an animal model. The changes in the allogeneic PV remained not answered, since the liver was considered an immune privileged organ and the portal presentation of the donor antigen induced transplant tolerance. This study aimed at the clinical strategy for replacement of resected portal vein by allograft in the pancreatic surgery. Therefore, we developed this PV transplantation model aimed at studying the pathologic alteration of the grafts.Materials and MethodsPart IWe reported 3 cases of portal vein transplantation for massive vascularinvolved pancreatic tumor during January 2004 to January 2006.Part IIFor animal investigation, C57BL/6 (H2~b) and BALB/c (H2~d) mice wereused as donors and recipients. Animals were allocated into the threegroups: group A, syngeneic transplantation; group B, allogeneictransplantation; group C, CTLA4-Ig treatment in allogeneictransplantation.ResultsA total of 80 PV grafts have been implanted with success rate of 91.3% (73/80). Graft wall remained unchanged in group A, nevertheless thickening of graft wall progressed rapidly with massive mononuclear infiltration in group B in the first 4 weeks. Graft wall thickness decreased from 4- to 8-week when the intima and the muscular layer were completely replaced by intercellular matrix. Compared to the group B, the CTLA4-Ig treated mice were revealed intact venous wall and attenuated rejection.ConclusionAllogeneic portal vein transplantation is an applicable alternative in radical resection of pancreatic tumor. Murine study indicated rejection events in the allogeneic grafts. CTLA4-Ig could possibly inhibited rejection and decrease graft wall thickness.