Changes Occurring in Intestinal Transplants

Changes Occurring in Intestinal Transplants

Total intestinal transplantation is used to correct the short gut syndrome. Pediatric candidates for intestinal transplantation are those who undergo extensive intestinal resections for gastroschisis, volvulus, and necrotizing enterocolitis, as well as those with functional disorders such as intestinal pseudo-obstruction, microvillous inclusion disease, and juvenile polyposis (652). The optimum treatment depends on buying time and hoping for maximal intestinal growth and adaptation.

Intestinal transplantation inevitably involves transection of the intestinal wall causing intrinsic and extrinsic denervation, interruption of lymphatic drainage, and preservation-induced injury. Immunologic reactions and immunosuppressive agents may further compromise normal intestinal function. Rejection of the transplant increases intestinal permeability, resulting in bacterial translocation and leading to
sepsis. The large amount of transplanted lymphoid tissue present in the Peyer patches, lamina propria, and mesenteric lymph nodes is responsible for the highly immunogenic character of intestinal allografts. Table 6.58 lists some of the major complications of intestinal transplantation.

TABLE 6.58 Complications of Transplantation

Preservation injury
Graft failure
Ischemic damage
Graft rejection
Graft vs. host disease
Posttransplant lymphoproliferative disorders

Lymphatic regeneration needs to occur following the graft to establish the lymphatic drainage so critical to the nutritional functions of the small bowel, including the absorption of chylomicrons. If this does not occur, lymphedema will develop. Lymphedema reduces absorption of nonlymphatic-dependent proteins and carbohydrates. Impaired gut barrier function may eventually lead to sepsis and multiorgan failure.

Part of the ability of the graft to function normally involves regeneration of the neural components. When failed grafts are evaluated, they demonstrate a lack of extrinsic adrenergic and perivascular fibers in all layers of the bowel wall, but intrinsic neural endocrine transmitters are preserved. Both peptidergic nerves and their receptors are retained following transplantation (653). Patients on cyclosporin therapy may have atypical changes in the bowel wall that do not allow one to detect GVHD or rejection.

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Jun 22, 2016 | Posted by in GASTROENTEROLOGY | Comments Off on Changes Occurring in Intestinal Transplants

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