The influence of surgery, immunosuppressive drugs, and rejection, on graft function after small bowel transplantation: a large-animal study

In this study we assessed functional changes (motility and absorption) of intestinal allografts in a large-animal model of orthotopic small bowel transplantation in swine. Studies were performed on non-rejecting animals in the early and late stages after transplantation and after induction of different grades of acute rejection. Immunosuppression consisted of oral FK506 and mycophenolate mofetil. In each study group we regulated drug administration, in terms of dosage and timing, in order to induce different grades of acute rejection or to prevent it. Migrating myoelectrical complexes were recorded in fasting animals so that motility could be assessed. Mucosal biopsy of the allograft and D-xylose absorption tests were performed on the same day as the motility study. In the early stages following intestinal transplantation, we observed in non-rejecting animals a slightly increased graft motility and a marked carbohydrate malabsorption. Recovery of the carbohydrate absorption capacity occurs within 2 months, but the persistence of diarrhea leads to partial malabsorption and to a lack of normal weight gain. Motility reduction correlates with the grade of acute rejection and becomes significant at a later stage, when rejection is severe. Allograft carbohydrate absorption, on the contrary, is markedly reduced in all rejecting pigs, irrespective of the grade of rejection. In summary, the early functional impairment of non-rejecting animals has multifactorial causes due to surgery and immunosuppression (drug toxicity), and its occurrence suggests the need for specific guidelines for clinical early postoperative enteral feeding. The functional studies adopted here are helpful in defining the grade of functional impairment with or without acute rejection; however, they are not useful for early detection of ongoing acute rejection of the small bowel graft.     

Laparoscopic harvesting of small bowel graft for small bowel transplantation

Background: Small bowel transplantation represents a valid therapeutic option for patients with intestinal failure, obviating the need for long-term total parenteral nutrition. Recently, reports have shown the feasibility of performing living related intestinal transplantation using segmental small bowel grafts. The limitations of this technique include inadequate harvested small bowel lengths, as compared with the lengths obtained in cadaveric small bowel harvests, and large incisions for the donor. In this pilot study, we evaluated the feasibility of laparoscopically harvesting long segments of proximal jejunum for small bowel transplantation using a porcine model. The results can be used to evaluate the potential for applying this technique in human cases. Methods: For this study 10 yorkshire pigs were used. Under general anesthesia, each pig underwent laparoscopic segmental resection of 200 cm of proximal jejunum on a vascular pedicle. The harvested graft then was autoreimplanted using an open technique by anastomosing the vascular pedicle to the superior mesenteric vessels. Success was determined 2 hours after anastomosis by visually identifying a pink graft with viable-appearing mucosa, an artery with a strong thrill, and palpable venous flow. The animals were then sacrificed. Results: The mean operation time required to laparoscopically harvest the small bowel graft was 80 min (range, 35–120 min), and the mean length of harvested graft was 220 cm (range, 200–260 cm). The mean length of the graft's vascular pedicle was 4.5 cm (range, 4–5 cm). All 10 grafts were successfully harvested laparoscopically and then reimplanted using an open technique. All the grafts maintained good vascular flow, and showed no evidence of mucosal necrosis at necropsy. Obviously, further studies would be required to examine the long-term results of reimplanting a laparoscopically harvested small bowel graft, but proposals for such studies is beyond the scope of this report. Conclusion: Minimally invasive techniques can be used to harvest proximal small bowel grafts for living related small bowel transplantation.     

Comparison of rejection rate and functional outcome of small bowel transplantation alone or in conjunction with the ileocecal valve versus combined small and large bowel transplantation

Preservation of the ileocecal valve improves absorptive function and decreases the amount of small bowel needed for survival in patients with short gut syndrome. We compared the results of small and large bowel transplant (SLBTx), small bowel transplant only (SBTx), and SBTx with the ileocecal valve (ICVTx) in a porcine model. Total enterectomy was performed on 18 Yorkshire-Landrace pigs followed by orthotopic SBLTx (n = 6), SBTx (n = 6), and ICVTx (n = 6). A jejunostomy and an ileostomy were constructed for biopsies. Overall mean survival was 17 d with no statistically significant difference between groups. Rejection was seen in 6/6 SLBTx, 4/6 SBTx, and 4/6 ICVTx recipients. Acute rejection was seen in 84.3% of SLBTx, 52.3% of SBTx, and 42.5% of the ICVTx mucosal biopsy samples. Two cases of intra-abdominal infection were in the ICVTx group only. Weight loss was 147 g/d in the SLBTx group, 643 g/d in the SBTx group, and 393 g/d in the ICVTx group. While the functional outcome after SLBTx and ICVTx was noticeably better than the SBTx group, the increased rejection and intra-abdominal infection rates make transplanting the large bowel or the ileocecal valve a less attractive clinical option.     

Cervical small bowel transplantation in the rat: a useful tool

Orthotopic intestinal transplantation in the rat is highly successful, but circumstances may require an extraabdominal graft location. We describe a microsurgical technique for cervical intestinal transplantation in the rat, which has been used to investigate the immune status of hosts already bearing an intraabdominal bowel transplant. A 10 cm segment of donor jejunum is harvested on a pedicle of superior mesenteric artery and superior mesenteric vein. In the recipient, the carotid artery (CA) and external jugular vein (EJV) are isolated. The venous anastomosis is performed end to end to the medial EJV branch, and the arterial anastomosis is completed end to side to the CA. Both anastomoses are performed with interrupted 10-0 nylon. The bowel is placed in a subcutaneous pocket in the neck, with both ends exteriorized. The procedure was performed in 11 donor-recipient pairs planned to elicit rejection, graft-vs.-host disease (GVHD) or graft acceptance. No technical complications were encountered. All rats survived long term, and their grafts were monitored histologically. The expected immune responses were observed, but rejection and GVHD were not fatal to the host with this model. We conclude that this technique is feasible and reliable to monitor the progress of isolated intestinal transplants. The location in the neck does not disrupt normal intestinal function of the recipient and may have multiple applications in the study of intestinal transplant immunology and physiology.     

Early referral is essential for successful pediatric small bowel transplantation: The Canadian experience

PURPOSE: The mortality rate for pediatric patients on the waiting list for transplantation has a major impact on the overall effectiveness of pediatric small bowel transplantation. This review was undertaken to determine the fate of Canadian children assessed for small bowel transplant and the outcome of those who undergo transplant in the tacrolimus era. METHODS: The authors reviewed retrospectively all of the pediatric small bowel patients listed since 1988 through the Canadian Organ Replacement Register and all the children referred to our program in its first year. All children who received a small bowel transplant between January 1993 and December 1999 also were reviewed. RESULTS: The mortality rate for pediatric patients on the small bowel transplant list was 53% after an average of 105 days on the list compared with 212 days for those who underwent transplant. Patients who died while on the list were younger and had signs of advanced liver disease at the time of listing. Thirteen Canadian children have received a small bowel transplant with an overall 1-year patient and graft survival rate of 61% and 53%, respectively. Survivors are all independent from total parenteral nutrition. CONCLUSION: Many Canadian children miss their opportunity for a successful small bowel transplant because of late referrals and a shortage of donor organs.     

Orthotopic small bowel transplantation in mice

On the basis of our experience with rat small bowel transplantation (SBT), we established a model of orthotopic SBT in mice. The immediate success rate was approximately 50%. Indefinite survival was obtained in the syngeneic group. The effect of different immunosuppressive treatments was also investigated: mean survival was 10.2+/-1.2 days in untreated mice receiving allogeneic grafts, 14.2+/-1.6 days with cyclosporine, 24+/-5.1 days in the rapamycin group, and 73.6+/-29.1 days with tacrolimus-treated animals. From this study, we conclude that although the model is technically difficult, it may provide an excellent tool to further investigate the physiology and immunology of small-intestinal transplantation.     

实验性小肠移植早期排斥标志物研究

为寻找小肠移植（ＳＢＴ）早期排斥标志物，本实验采用逆转录聚合酶链式反应技术，对小鼠ＳＢＴ术后１２小时受体Ｔ细胞表面白细胞介素－２受体α链（ＩＬ－２Ｒα）编码基因进行定性检测，并对移植小肠行同期病理学检查。结果发现：同种异体移植小鼠体内ＩＬ－２α ｃＤＮＡ阳性例数均明显高于非手术、同系移植及加环孢素Ａ（ＣｓＡ）治疗的同种异体移植小鼠；移植小肠病理学检查无异常变化。提示：Ｔ细胞表面ＩＬ－２Ｒα基因的活     

Recipient FK506 pretreatment regimens in rat small bowel transplantation: allograft survival, function, and systemic infection

PURPOSE: Successful small bowel transplantation requires effective immunosuppression that preserves intestinal function but avoids opportunistic infection. This study aims to evaluate FK506 as a single immunosuppressant in different pretreatment regimens in a rat high responder strain combination. METHODS: Lewis --> DA rat heterotopic small bowel transplantation was performed. Studied groups were (1) untreated control, n = 12; (2) FK-1, n = 8; (3) FK-3, n = 8. FK506 (2 mg/kg/d, intramuscularly) was given to the recipients for 1 day (FK-1) and 3 days (FK-3) before small bowel transplantation, followed by 2 weeks of subtherapeutic treatment (0.3 mg/kg/d, intramuscularly) after small bowel transplantation. Syngeneic small bowel transplantation also was performed (n = 8). FK blood levels, maltose absorption test, histology, and bacteriology were performed at different postoperative days. RESULTS: Allograft survival was prolonged significantly with FK pretreatment, being more so in FK-3 group (FK-1, 22.2 +/- 1.5 d; FK-3, 40.7 +/- 14.1 d; control, 6.6 +/- 0.8 d; P< .01). In the first postoperative week, FK blood level was significantly higher in FK-3 group (19.8 +/- 1.5 ng/mL) than in FK-1 group (5.0 +/- 0.4 ng/mL; P < .05). There was no evidence of systemic infection in either FK-treated group. For maltose absorption, control allograft was abnormal on day 7 correlating to severely damaged intestinal architecture. In contrast, FK-treated allografts showed well-protected intestinal structure and normal absorption on days 7 and 21. CONCLUSION: High FK506 blood levels in the first postoperative week, achieved with FK pretreatment, prolonged intestinal allograft survival and preserved intestinal structure and function without allowing systemic infection.     

小肠移植后排斥反应的监测

检测猪同种异体小肠移植后受体的血浆Ｎ－乙酰氨基已糖酶，外周血单个核细胞前凝血质活性，血清肿瘤坏死因子，血清白细胞介素２和白细胞介素６，并与同期的粘膜活检结果对照，发现它们在排斥早期即有显著升高，其是单个核细胞前凝血活性和白细胞介素２的变化早于反排斥反应的病理变化，提示术后检测这些指标将有助于排斥反应的早期诊断。     

Living-related small bowel transplantation: two cases experiences

We have recently performed living-related small bowel transplantation for 2 patients. The first patient was a 14-year-old boy with total parenteral nutrition (TPN)-dependent short-bowel syndrome associated with hypoganglionosis of the entire intestine. He received a bowel graft from his 43-year-old mother. The second patient was a 27-year-old woman, who had massive enterectomy due to volvulus and developed vitamin deficiencies and severe metabolic disorders as a result of long-term TPN. She underwent living-related bowel transplantation from her 57-year-old mother. Blood types were ABO identical, cytotoxic cross matches were negative, and cytomegalovirus statuses were positive-to-positive in both cases. Up to one third of the donor bowel was harvested from the donor distal ileum more than 30 cm away from the ileocecal valve. The graft vessels were connected to infrarenal aorta, and inferior vena cava. The immunosuppressive regimen consisted of daclizumab, tacrolimus, and steroid. The graft surveillance was accomplished using zoom endoscopy and mucosal biopsy. The first patient developed progressive acute cellular rejection (ACR) on the 9th postoperative day (POD)-9 requiring OKT-3 therapy, which was effective. Two months after transplantation, he was weaned from TPN, tolerating oral intake with a fully functioning graft. The second patient experienced no episode of ACR and was weaned off TPN on POD-29 with a functioning graft. Her metabolic disorder dramatically improved after bowel transplantation. Both donors had no complication and were discharged from the hospital on POD-10. Living-related bowel transplantation is an extreme option of treatment for patients with short-bowel syndrome.     

Serum citrulline and rejection in small bowel transplantation: a preliminary report

BACKGROUND: There is no known serum marker for intestinal rejection. Serum concentrations of the amino acid citrulline arise almost exclusively from the intestinal mucosa. We examined the impact of acute cellular rejection (ACR) of intestinal allografts on serum citrulline levels. METHODS: Citrulline concentrations were assayed in serum samples of healthy volunteers (n=6) and seven patients who underwent small bowel transplants (SBTx). Trends in mean citrulline concentrations versus degree of ACR were assessed by matching posttransplantation citrulline concentrations with patients' grade of ACR at time of serum collection. Rejection was confirmed by biopsy and graded by following standardized criteria. An additional patient had citrulline concentrations determined for 31 sequential specimens 3-60 days posttransplant. RESULTS: Mean citrulline concentrations in controls were significantly higher than posttransplantation samples at any rejection grade. Mean concentrations declined significantly as rejection severity increased. The overall downward trend was statistically significant (P<0.05). In sequential measurements, citrulline levels increased significantly over time with declining severity of rejection. The increase in mean citrulline concentration between posttransplant days 3-16 and 52-60 was significant (P<0.01). CONCLUSIONS: Serum citrulline levels decline with increasing grade of ACR and may be a useful serum marker for intestinal rejection.     

Colon vs small bowel rejection after total bowel transplantation in a pig model

Abstract  With the advent of FK506, small bowel transplantation has become clinically feasible. Both clinically and experimentally, jeju-nal and ileal biopsies are used for early diagnosis of rejection. More recently, the colon, in addition to the small bowel, has been transplanted to decrease the high incidence of diarrhea after small bowel transplantation. A Bishop-Koop ileostomy allows biopsies on a regular basis, but the diagnosis of rejection remains a problem after takedown of the ileostomy. Rejection of the il-eum is more frequent and more severe than rejection of the jejunum or the colon. Colon biopsy after ileostomy takedown would not rule out rejection of the ileum.     

Early postoperative small bowel obstruction: A review

Early postoperative small bowel obstruction (ESBO) is a challenging problem. Although it is usually amenable to non-operative management, a significant proportion of patients will require re-operation. Certain causes of ESBO and types of index procedures should prompt consideration for early re-operation. A laparoscopic approach during the index operation, certain barrier agents and closure of mesenteric defects in bariatric surgery may reduce the risk of ESBO. There is no consensus regarding an acceptable length of time for initial non-operative management of ESBO but re-operation beyond two weeks may be associated with increased complications.     

Perioperative analgesia in experimental small bowel transplantation

BACKGROUND: Despite numerous studies in experimental rat small bowel transplantation (SBT), few authors make reference to perioperative analgesia. Recent changes to the Animals (Scientific Procedures) Act 1986 in the United Kingdom have made the use of analgesia in laboratory animals compulsory because pain is unnecessary in the majority of scientific procedures. METHODS: Heterotopic SBT (PVG-->DA) was performed on male rat recipients weighing 220 to 250 mg under isoflurane with a mean anesthetic time of 100 minutes. Recovery from anesthesia was usually within 15 minutes. Analgesia regimens were based on those in common use for other procedures. All drugs were administered in the 30 minutes prior to recovery from anesthesia. Group A received carprofen (2 mg/kg IM or SC). Group B was given buprenorphine (0.05 mg/kg either IM or SC). Group C received paracetamol (10- 30 mg) rectally. An early postoperative scoring system of four criteria was used, giving a maximum (least desirable) score of 16. Sixty transplants were performed, divided between the three groups. RESULTS: In group A animals scored a median of 1 of 16 but all except three recipients died within 3 hours. Those in group B scored a median of 8 of 16, but all animals except one died between 4 to 16 hours after surgery. Group C had a median score of 11 of 16, but there was no early mortality. Postmortem examination excluded technical failures in all but three animals. CONCLUSION: We recommend the use of paracetamol for perioperative analgesia in SBT because of the high mortality associated with other drugs when used in this procedure.     

Cadaveric small bowel/split liver transplantation in a child

Scarcity of size-matched grafts continues to be a major limiting factor for liver and combined liver/intestinal transplants in the pediatric population. It is reported that 29 % of pediatric patients listed for hepatic transplantation die while waiting for a donor. The reported mortality of pediatric patients awaiting intestinal transplantation is about 40 %. We report on a technique of segmental liver and intestinal transplantation in a child. To our knowledge, this is the first report of a combined split liver-intestinal transplantation. We used a cadaveric donor, but the technique can also be performed with a live donor. The adult recipient of one segment of the liver was discharged home without complications. The child who received the combined liver intestinal graft developed intestinal perforation and severe rejection and died. If this technique is applied successfully, the adverse effects and mortality of a long pretransplant waiting period in pediatric patients may be avoided. Received: 7 May 1998 Received after revision: 29 September 1998 Accepted: 12 October 1998     

小肠移植后亚临床排斥反应的临床病理研究一例

目的 探讨小肠移植后亚临床型细胞性排斥反应(SCR)的临床表现、肠镜下改变和病理特点.方法 小肠移植1例,受者为女性,34岁,供者为男性.应用抗CD52单克隆抗体行诱导治疗,术后单用他克莫司(Tac)、无皮质激素的维持治疗方案.怀疑发生可疑排斥反应(IND)级至I级排斥反应时,提高血Tac浓度,行短程小剂量皮质激素治疗,排斥反应控制不佳时,则行甲泼尼龙冲击治疗;发生中度排斥反应时提高血Tac浓度,给予甲泼尼龙2 g,随后应用皮质激素递减方案.术后头2个月内,每周行2次肠镜和病理学检查,之后频次减为1次/周.结果 至随访结束患者已存活19个月(611 d),期间共发生有临床症状的急性排斥反应6次,亚临床排斥反应3次.3次亚临床排斥反应时,2次肠镜下未见明显改变,1次表现为斑点状的充血、水肿,放大肠镜下绒毛数量轻度减少.3次亚临床排斥反应的病理检查中,1次以黏膜上皮剥脱为主,隐窝上皮损伤较轻,组织学改变符合轻度急性排斥反应;而另2次以隐窝上皮的损伤为主,为可疑急性排斥反应.结论 SCR可能是临床排斥反应的早期阶段,无明显临床症状,肠镜下改变不明显,诊断主要依靠病理学检查,但必须排除移植肠血管病变、肠梗阻、各类炎症等术后并发症.