Ileal nutritional function after one-stage orthotopic ileum transplantation in the growing pig: Reversal of lethal short bowel syndrome

Abstract

Listen

Translate article

Intestinal isolation is associated with hypoplasia of defunctioned mucosa and reduction in the segmental absorption, whereas the presence of luminal nutrition is essential for the expression of the ileal adaptive response after proximal small bowel resection. On the other hand, intensive postoperative graft monitoring is obligatory because of the disastrous consequences of small bowel graft rejection. Thus, the authors sought to develop an experimental ileum transplantation model that provided immediate graft placement in bowel continuity, together with readily available graft monitoring connection through a proximal Roux-en-Y enterostomy. Four groups of pigs were prepared: RESTX (n = 9), proximal 50% small bowel resection with simultaneous orthotopic ileum autotransplantation; RES (n = 7), proximal 50% small bowel resection; NONRES (n = 6), transection; and SB (n = 5), short bowel. Early (1 to 4 weeks) and long-term (5 to 12 weeks) studies of animal growth, nutritional status, disaccharide absorption, water and electrolyte balances, and liver function were performed after ileum autotransplantation (IAT) in relation to small intestine of variable length with undivided mesentery (intact neural and lymphatic connections). The perioperative transplantation mortality rate remained at about 10%. Reasons not related to the transplantation procedure accounted for the late complication rate of 38%. In the ileum autotransplantation (RESTX) group, weight gain was recovered 2 to 3 weeks after transplantation, and the mean weight reached the preoperative level at 5 weeks. The SB pigs underwent progressive weight loss. The transection (NONRES) and proximal resection (RES) animals gained weight at similar rates. IAT had no effect on the plasma protein concentrations. Proximal resection, with or without IAT, was associated with depressed plasma cholesterol contents in the early period. Plasma cholesterol levels amended long-term, after both IAT and proximal resection. IAT resulted in deficient intraluminal processing of maltose, whereas isolated proximal resection tended to enhance disaccharide absorption early after the surgery. The short bowel pigs were not able to preserve sufficient nutritional status, and demonstrated a marked decline in the hemoglobin, protein, and cholesterol levels. No biochemical signs suggestive of potential liver damage caused by portocaval graft vascularization were recognized. These findings suggest that one-stage ileum autotransplantation provides sufficient absorptive capacity to reverse otherwise lethal short bowel syndrome in the growing pig. However, transplantation disturbs the in vivo absorptive function of the nonrejecting ileum. Long-term impairment in disaccharide absorption may be partially related to an altered intestinal adaptive response secondary to proximal resection when combined with simultaneous transplantation. The authors developed this ileal small bowel transplantation model using rapidly growing pigs, wherein body weight gain represents an objective parameter of intestinal absorptive function. Only this type of animal model can yield clinically relevant data in the evaluation of a transplant's ability to provide sufficient nutritional function in a growing recipient.