When the intestine has been injured beyond repair or no longer functions well enough, transplantation is an option. The prob-lem is that this organ contains a lot of tissue from the lymphatic system—a system that carries immune cells. When a donor’s small intestine is transplanted, those immune cells, which normally fight foreign substances and infec-tion, may attack the recipient’s tissue, causing a condition called graft-versus-host disease. In addition, the new organ may be rejected.

Basics of transplantation

To succeed, an organ transplantation requires a good tissue match between the donor and recipient. That is key to preventing rejection of the organ. Tissue matches are determined by comparing sets of proteins on the surface of cells. These proteins, called HLA antigens, are unique to each person. Because family members share many of the same HLA genes, they are more likely to have similar antigens and tissue types.

Sometimes, however, no good family match exists and time is of the essence. The person in need cannot wait for the ideal donor. In this case, a less suitable match may be used. To minimize the chances of organ rejection, the recipi-ent receives drugs to suppress his or her immune system. Introduction of the immunosuppressive drug tacrolimus marked an important advance in small intestine transplantation.

While these drugs stifle the immune system’s reaction to the new organ, they also impair the system’s ability to pro-tect the person against infection. And most medications must be taken for life.

Getting a new small intestine

The University of Pittsburgh Medical Center has performed more small intes-tine transplants than any other institu-tion in the world. Currently, the medical center performs 60 such operations each year. That surgical experience gives the doctors the best perspective on this procedure. While early episodes of rejection are fairly common, they are usually reversed with short-term courses of high-dose corticosteroids.

But how well do those people do later? To find out, a team of research-ers at the University of Pittsburgh reviewed all those who had received a small intestine transplant between June 2003 and July 2004, following them for 1 to 3 years after surgery. The goal was to evaluate the recipients’ ability to eat without a feeding tube, the transplanted organ’s function, and the recipients’ general quality of life.

Free of the feeding tube

The team looked at 46 people who had undergone small intestine trans-plantation (61% also received a liver), as well as 13 who were on total par-enteral nutrition (TPN) at home. TPN involves feeding through a catheter (tube) implanted in a large vein. The method provides critical nutrition for people who can’t absorb food through their small intestine, but it can lead to infection and other complications.

The main reason for intestinal failure in the patients studied was too little small bowel, due to repeated opera-tions for Crohn’s disease and related conditions. Most required a transplant after suffering repeated infections while on TPN.

During the follow-up period, 5 people died—2 of them from organ rejection. None of the others lost their transplant-ed small intestine to rejection. After 21 months, the average survival rate for both patient and tissue graft was about 90%. After surgery, nutrition was pro-vided through TPN. But TPN was dis-continued in all transplant patients—on average, after 18 days. Their quality of life, as measured by a questionnaire, improved significantly in 25 of the 26 areas tested, including anxiety, depres-sion, stress, and quality of personal relationships. Their reports of organ function indicated improvement as well.

More candidates for surgery?

Previously, small intestine transplan-tation was regarded as so experimental that the only reason to consider it was if TPN failed. That thinking is now changing, as newer immunosuppres-sant drugs have boosted survival rates and the positive impact of transplanta-tion on patients’ quality of life becomes evident. These considerations, say the researchers, may lead to broadening the indications for the operation.

From American Journal of Gastroenterology