A modified technique for small-bowel transplantation in the rat

Abstract

The rat model for small-bowel transplantation is becoming increasingly popular. The currently accepted microsurgical technique, however, is complicated by extensive dissection in the donor rat vascular system requiring a great deal of manipulation of the vessels themselves, with consequent complications of thrombosis and vascular injury. We describe a procedure for small-bowel transplantation in the rat that simplifies the currently accepted technique. The peripheral portion of the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) is used as the vascular pedicle of the segment of bowel to be transplanted rather than the SMA with an aortic cuff and the portal vein as previously described. The SMA and SMV are anastomosed to recipient aorta and inferior vena cava respectively. The bowel extremities are exteriorized, thus leaving access to the lumen for further studies. All anastomoses are performed with interrupted 10-0 nylon sutures. The procedure was performed in 11 animals. Good revascularization of the transplant was defined as immediate filling of the transplant vasculature with normal (pink) appearing bowel. Eight of the recipients had excellent revascularization. Venous occlusion was the cause of early failure in the remaining three animals. All animals were killed, autopsies performed, and the anastomoses examined. The longest survivors were killed at 7 months. Biopsies were obtained immediately and at daily intervals. Early ultrastructural changes of rejection in the transplanted bowel were studied by electron microscopy. Changes in the microvasculature were seen early after transplantation. Immunologic changes were apparent only later in the course of rejection. We conclude that this technique is successful in achieving functional small-bowel transplants in the rat. Manipulation of the vessels is greatly decreased, and one operator may perform the entire procedure in a short time. Further experimental applications such as long-term ultrastructural studies and the effects of immunosuppressive agents are discussed. Speculation is made on possible clinical applications of the microsurgical technique as well as the use of electron microscopy for early monitoring of rejection.