An Ideal Model Of Mouse Heterotopic Vascularized Segmental Pancreas Transplantation

BackgroundVascularized pancreas transplantation is currently the treatment of choice in patients with IDDM,which is also the only established method to achieve long-term normoglycemia and insulin independence.However,the results of single pancreas transplants have not improved in recent years,50%of pancreas-only transplants failed within 6 months,with only 41%survival rate of the 4-year graft for single pancreas transplants.Evidence suggests that the grafts failed for many reasons,including immunological reasons,recurrent disease and rejection.Ischemia reperfusion injury (IRI) with consecutive graft pancreatitis being the risk of acute graft failure which is reported to occur with an incidence of up to 35%is still one of the most significant nonimmunologic complications after pancreas transplantation.The reasons for IRI include microcirculatory disorders,endothelial cell activation,expression of proinflammatory cytokines,adhesion molecules,loss of endothelial integrity and so on.For better understanding of the molecular basis of pathophysiology and immunology,especially in terms of IRI,we have tried to develop a mouse pancreas transplantation model.Howcver mouse pancreas transplantation models need precise microsurgical procedure,it is more advantageous than rat models,compare with rat model it is cheaper and more immunological methods can be applied,better for researching in transplantation immunology.By using the cuff technique,we designed an ideal,simplified mouse model of cervical heterotopic vascularized segmental pancreas transplantation.MethodsMale Balb/c mice were used as donor and recipient pairs,randomly assigned to the two different experimental groups,without cold storage in groupⅠ(Ⅰ=6),exposed to 16 h of cold ischemia(Pancreatic grafts were preserved in University of Wisconsin solution for 16 h at 4℃) and then transplanted in groupⅡ(n=6).Warm ischemia,defined as the time during organ harvest and revascularization,was strictly kept to 45 min in both groups.The donor pancreas was isolated by using a no-touch technique and then placed in the recipient's cervical region by using the cuff technique.After 2h of reperfusion, inject FITC(MW 150000;50g/kg body weight;Sigma,Deisenhofen,Germany) through caudal vein,graft were retrieved for intravital microscopy(IVM),analyzed by means of functional capillary density(FCD),capillary diameters(CD) intravital microscopy. Blood samples were obtained from the subhepatic interior vena cava to measure the blood amylase levels using a clinical biochemistry machine.Remove the graft for HE stain and immunohistochemical.All statistic analysis was performed with SPSS11.6 software and P-value＜0.05 was considered as significant.ResultsThe immediate success rate was＞90%.Donor operation lasted 40±5 min; dissection of recipient vessels lasted 20±5 min.Revascularization time was 5 to 10 min, resulting in a total pancreas ischemia time of 30±5 min.Postoperative 2h,the blood amylase levels of GroupⅠ(1096.5±652.3u/l) is lower than GroupⅡ(2803.7±1902.0u/l,P＜0.05);Histology on postoperative 2h showed almost normal of all grafts. The scorce of Group is lower than GroupⅡin inflammation and similar in edema, acinar necrosis and hemorrhage;In groups with prolonged cold ischemia(GroupⅡ), graft microcirculation(FCD) was significantly reduced than GroupⅠ(P＜0.05),the CD of two Group has no difference.ConclusionWe conclude that our model is more physiological and would be benefit for studying various transplantation-related problems.