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Intestinal adaptation is a spontaneous compensation of the remanent bowel after extensive enterectomy, which improves the absorption capacity of the remanent bowel to energy, fluid and other nutrients. Intestinal adaptation mainly occurs within 2 years after enterectomy, including morphological changes, hyperfunction and hyperphagia. Intestinal adaptation is the key factor for patients with short bowel syndrome to weaning off parenteral nutrition dependence and mainly influenced by length of remanent bowel, type of surgery and colon continuity. In addition, multiple factors including enteral feeding, glucagon-like peptide 2 (GLP-2), growth hormone, gut microbiota and its metabolites regulate intestinal adaptation via multi-biological pathways, such as proliferation and differentiation of stem cell, apoptosis, angiogenesis, nutrients transport related protein expression, gut endocrine etc. Phase III clinical trials have verified the safety and efficacy of teduglutide (long-acting GLP-2) and somatropin (recombinant human growth hormone) in improving intestinal adaptation, and both have been approved for clinical use. We aim to review the current knowledge about characteristics, mechanism, evaluation methods, key factors, clinical strategies of intestinal adaptation.

Objective: To investigate the result in treating short bowel syndrome with living-related small bowel transplantation., Methods: Two patients with short bowel syndrome underwent living-related small bowel transplantation. One patient was an 18-year-old boy and the donor was his father. A segment of 150 cm distal small bowel was resected as the graft from the donor. Another patient was a 15-year-old boy and the donor was his mother. The graft was 160 cm long, with arteries and veins anastomosed to the recipient's infrarenal aorta and cava respectively. Intestinal continuity was restored with an end-to-end anastomosis between the recipient's jejunum and the donor's ileum, and the distal end was made as fistulization. Treatment of immunosuppression, antibiotics, anti-thrombosis and nutritional support were given posttransplantation., Results: Complications such as anaemia and acute rejection occurred in the first recipient and were handled properly and brought under control after operation. The patient has been surviving 26 months since the transplantation. The graft's function is well. The patient can eat food and resume his daily work. In the second recipient, acute rejection occurred on day 26 after operation and was controlled by implosion therapy. Serious rejection occurred on day 80 again and did not respond to implosion therapy with methylprednisolone. After use of OKT3 and ATG the rejection was minimized. Because of uncontrolled infection, the patient died on 5th month after operation., Conclusion: Living-related small bowel transplantation is an ideal treatment for short bowel syndrome.

Basing on the establishment of an isolated bowel segement (IBS) in Beagle dog by omentoenteropexy, the possibility of using omentum as vascular pedicle in bowel elongation was investigated. Five young Beagle dogs (3 females, 2 males) with a body weight of 5-9 kg were used. A longitudinal incision (15 cm long) was made down to the seromuscular layer of the jejunal segment on the antimesenteric border, 20 cm distal to the duodenojejunal fold, the mucosal layer should never be injured. Then the free margin of the omentum was attached to the seromuscular border of the jejunum by interrupted sutures. One dog died from volvulus and necrosis of the bowel 3 days after operation. Seven weeks later, the mesentery was ligated in one dog and the bowel lengthening procedure was carried out in the other 3 dogs. The procedure consisted of longitudinal splitting of the isolated bowel segment anteroposteriorly, thus two separated segments of bowel were obtained, each received its own blood supply from either omental or mesenteric blood vessels. Either of the longitudinally splitting segments was rebuilt into one intestinal canal by 3/0 non-traumatic sutures. Then isoperistaltic end-to-end anastomosis of these two isolated segments was carried out, and an jejunostomy was established. The free jejunal ends were rejoined together to restore the continuity of the bowel lumen. Two weeks later, the blood supply of the experimental bowel segment was observed. It was shown that the IBS and elongated bowel segment (EBS) appeared viable, and there was good collateral circulation between the bowel segment and the omentum. The regeneration of lymphatics was observed from injection of methylene blue. It was concluded that a viable IBS and EBS could be established by using omentoenteropexy technique. The application of the this model in the management of short bowel syndrome needed to be further investigated.

The pigs with allograft were divided into 5 groups according to the different immunosuppressive regimens. Acute rejection of allograft occurred in animals not treated with immunosuppressive agents or treated with low dose of cyclosporine (CsA). There was no rejection developed in the pigs treated with high dose CsA or low dose CsA and tripterygium wilfordii (TW). No evidence of chronic rejection was detected in animals with continued administration of TW after living longer than 100 days when the immunosuppressive treatment was discontinued. A woman with enterocolitis, ileus and short-gut syndrome received a complete cadaveric small bowel transplantation in march 12, 1994. The graft had 6 minutes for warm ischemia and 9 hours and 45 minutes for cold ischemia. The immunosuppressive therapy consisted of CsA, TW and methylprednisolone. The patient is alive and the function of graft is normal.