Experimental model of liver transplantation large-for-size in growing animals: morphometric, histological and molecular studies

Abstract

Liver transplantation has well established its role in the definitive treatment of end-stage liver disease in children. The main indication for this procedure in children is biliary atresia (BA), totaling 60% of cases.The BA is characterized by a progressive inflammation and sclerosis causing obliteration of the bile ducts and biliary cirrhosis. When the diagnosis is early, Kasai procedure takes place in an attempt to restore bile flow and prevent disease progression. However, approximately 25% of children undergoing this procedure and those where the diagnosis is delayed presents with severe liver dysfunction in the first year of life associated with severe malnutrition. Thus, the indication of liver transplantation in small children has become commonly performed, existing studies in children under 5 kg.In transplantation performed between a donor adult and pediatric a recipient, the graft is made, usually the left lobe or left lateral segment whose average masses are between 400 to 500 g and 200 to 350 g, respectively. The choice of graft is based on the relationship between mass and weight of the graft recipient with proper ratio of 1 to 3%. With the shortage of donors, increasingly faced with the need to perform a transplant from a donor of 80 to 90 kg for a child of 4 to 6 kg.It is known that if the relationship between graft weight and liver weight is greater than 5%, the blood perfusion of the graft may be insufficient, which can lead to organ dysfunction. This situation is known as large-for-size syndrome. Moreover, the volume occupied by the graft creates difficulties in closing the abdominal cavity, causing abdominal compartment syndrome. Among the animal models of liver transplantation, using pigs presents a series of advantages such as size and anatomical similarities with the human structures, which allows, in addition to scientific studies, technical training. The objectives of this study are standardize a model of large-for-size syndrome, performing transplants between pigs with weights disproportionate and compared by means of biochemical analysis, histology and immunohistochemistry, the mechanisms of liver injury in the situation of large-for-size syndrome with transplantation in animals of similar size.Will be performed 30 transplants using 60 animals, 30 donors and 30 recipients. Half of the procedures will be disproportionate weight among animals with taking the situation for large-size and half between animals with similar weight.The pigs will be kept alive until 6 hours after reperfusion. Blood samples will be collected for biochemical analysis will be performed liver biopsies and 1, 3 and 6 hours after reperfusion. The material obtained in the biopsies will be subjected to histological analysis (reperfusion injury), immunohistochemistry using TUNEL and PCNA antigens (cell replication and apoptosis) and molecular method using qRT-PCR to quantify the apoptosis-related genes Bax and Bcl2. (AU)