The current status of small bowel transplantation in the UK and internationally

Small intestinal transplantation should now be routinely considered for patients with irreversible intestinal failure and complications of parenteral nutrition (PN). Although technically possible for a century,1 and attempted in humans for more than 40 years,2 immunological graft intolerance presented an impenetrable barrier to successful engraftment until the development of the powerful calcineurin inhibitor immunosuppressive agents in the late 1970s. Their subsequent clinical use over the past 17 years has transformed small intestinal transplantation from a position of predictable failure to predominant success and routine clinical reality for a select group of patients One year graft survivals for solid organs are now excellent and have been improving steadily since the introduction of ciclosporin to routine clinical practice in the early 1980s.3,4 In contrast, survival values for small intestinal transplantation have been slow to improve although are now comparable with those for lung, and the latest published values for one year survival approximate those for liver and kidney (table 1) Why then has progress with intestinal transplantation been so much more difficult? View this table: Table 1  Patient and graft survival of patients receiving small intestinal and solid organ grafts The technical feasibility of the procedure has been established for a century1 but immunological feasibility was far more difficult to establish. The high density of lymphoid tissue and the large mucosal surface area of the small intestine expressing class 2 major histocompatability antigens fuels the mutual intolerance between graft and host. As a hollow organ whose lumen is colonised by a multitude of bacteria and other micro-organisms, it behaves as a potent vector of infection to the host, a problem that is made worse by the precarious barrier from the lumen provided by the thin and vulnerable monolayer of mucosal epithelium. Here then is the fine balance between immunosuppression and infection that …