Enzymes activity of intestinal grafts after liver small bowel transplantation in rats

OBJECTIVES: To investigate the activity alterations of enzymes in intestine grafts after liver/small bowel transplantation in rats and the relations of these changes to immune rejection of grafts. METHODS: A model of liver/small bowel transplantation (LSBT) was established in closed colony SD and Wistar rats. The activity of enzymes including triphosphatase (ATPase), alkalinophosphatase (AKP), acytelcholinesterase (AchE), oxidesynthase (NOS) and monoamine oxidase (MAO) in bowel grafts was studied histochemically at regular postoperative intervals. RESULTS: The activity of enzymes in the wall of the grafts disappeared eventually in isolated small bowel transplantation (SBT) rats. In contrast, the activity in LSBT rats remained and recovered postoperatively. CONCLUSIONS: The rejection in grafted intestine could be prevented or delayed in LSBT rats. The changes in the activity of enzymes and neurons might be used to detect the rejection and function of the graft.

Mesenchymal stem cell therapy in patients with small bowel transplantation:Single center experience

AIM: To study the effects of mesenchymal stem cell (MSC) therapy on the prevention of acute rejection and graft vs host disease following small bowel transplantation.

Diagnosis and treatment of acute rejection in the first case of human living-related small bowel transplantation with a long-term survival in China

AIM： To report the comprehensive diagnosis and treatment of acute rejection in the first case of living-related small bowel transplantation with a long-term survival in China. METHODS： A 18-year-old boy with short gut syndrome underwent living-related small bowel transplantation, with the graft taken from his father （44-year old）. A segment of 150-cm distal small bowel was resected from the donor. The ileo-colic artery and vein from the donor were anastomosed to the infrarenal aorta and vena cava of the recipient respectively. The intestinal continuity was restored with an end-to-end anastomosis between the recipient jejunum and donor ileum, and the distal end was fistulized. FK506, MMF and prednisone were initially used for post-transplant immunosuppression. Endoscopic observation and mucosal biopsies of the graft were carried out through the terminal ileum enterostomy; serum was collected to detect the levels of IL-2R, IL-4, IL-6 and IL-8. The change of the graft secretion and absorption was observed. RESULTS： Acute rejection was diagnosed promptly and cured. The patient was in good health, 5 years after living- related small bowel transplantation. CONCLUSION： The correct diagnosis and treatment of acute rejection are the key to the long-term survival after living-related small bowel transplantation.

Protective effect of L-arginine preconditioning on ischemia and reperfusion injury associated with rat small bowel transplantation

AIM: To investigate the protective effect and possible mechanism of L-arginine preconditioning on ischemia and reperfusion injury associated with small bowel transplantation (SBT).METHODS: Male inbred Wistar rats weighting between 180 and 250 g were used as donors and recipients in thestudy. Heterotopic rat SBT was performed according to the techniques of Li and Wu. During the experiment, intestinal grafts were preserved in 4 ℃ Ringer's solution for 8 h before being transplanted. Animals were divided into three groups. In group 1, donors received intravenous L-arginine (50 mg/kg, 1 mL) injection 90 min before graft harvesting. However, donors in control group were given normal saline (NS) instead. In group 3, six rats were used as sham-operated control. Specimens were taken from intestinal grafts 15 min after reperfusion. Histological grading, tissue malondialdehyde (MDA) and myeloperoxidase (MPO) levels were assessed. The graft survival of each group was monitored daily until 14 d after transplantation. RESULTS: Levels of MDA and MPO in intestine of shamoperated rats were 2.0±0.22 mmol/g and 0.66±0.105 U/g. Eight hours of cold preservation followed by 15 min of reperfusion resulted in significant increases in tissue MDA and MPO levels. Pretreatment with L-arginine before graft harvesting resulted in lower enhancement of tissue levels of MDA and MPO and the differences were significant (4.71±1.02 mmol/g vs8.02±3.49 mmol/g, 1.03±0.095 U/g vs 1.53±0.068 U/g, P＜0.05). Besides, animals in L-arginine pretreated group had better histological structures and higher 2-wk graft survival rates comparing with that in NS treated group (3.3±0.52 vs6±0.1, 0/6 vs6/6, P＜0.05or 0.01).CONCLUSION: L-arginine preconditioning attenuates ischemia and reperfusion injury in the rat SBT model,which was due to antioxidant activities partially.

Formation of microchimerism in rat small bowel transplantation by spienocyte infusion

AIM： To investigate the effect of donor splenocyte infusion combined with cyclosporine A （CsA） on rejection of rat small bowel transplantation （SBT）. METHODS： Male Sprague-Dawley （SD） rats and female Wistar rats weighing 230-270 g were used as donors and recipients respectively in the study. Heterotopic small bowel transplantation was performed. The rats were divided into three groups： group one receiving allotransplantation （SD→Wistar）, group two receiving allotransplantation （SD→Wistar） ＋ donor splenocyte infusion, group three receiving allotransplantation （SD →Wistar） ＋ donor splenocyte infusion ＋ CsA followed by CsA 10 mg/kg per day after transplantation, in which recipient Wistar rats were injected with 2 ×10^8 SD splenocytes 28 d before transplantation, and treated with CsA after transplantation. Finally, the specific DNA fragment of donor Y chromosome was detected in recipient peripheral blood and skin by PCR. The survival time after small bowel transplantation was observed. Gross and histopathological examinations were performed. RESULTS： The survival time after small bowel transplantation was 7.1 ± 1.2 d in group 1, 18.4 ± 3.6 d in group 2 and 31.5± 3.1 d in group 3. The survival time was significant longer （P 〈 0.01） in group 3 than in groups 1 and 2. The gross and histopathological examination showed that the rejection degree in group 3 was lower than that in groups 1 and 2.CONCLUSION： Donor splenocyte infusion combined with CsA decreases remarkably the rejection and prolongs the survival time after rat small bowel transplantation.

Gut microbiota and its implications in small bowel transplantation

The gut microbiota is mainly composed of a diverse population of commensal bacterial species and plays a pivotal role in the maintenance of intestinal homeostasis, immune modulation and metabofism. The influence of the gut microbiota on solid organ transplantation has recently been recognized. In fact, several studies indicated that acute and chronic allograft rejection in small bowel transplantation （SBT） is closely associated with the alterations in microbial patterns in the gut. In this review, we focused on the recent findings regarding alterations in the microbiota following SBT and the potential roles of these alterations in the development of acute and chronic allograft rejection. We also reviewed important advances with respect to the interplays between the microbiota and host immune systems in SBT. Furthermore, we explored the potential of the gut microbiota as a microbial marker and/or therapeutic target for the predication and intervention of allografl rejection and chronic dysfunction. Given that current research on the gut microbiota has become increasingly sophisticated and comprehensive, large cohort studies employing metagenomic analysis and multivariate linkage should be designed for the characterization of host-microbe interaction and causality between microbiota alterations and clinical outcomes in SBT. The findings are expected to provide valuable insights into the role of gut microbiota in the development of allograft rejection and other transplant-related complications and introduce novel therapeutic targets and treatment approaches in clinical practice.

Experimental small bowel preservation using Polysol: A new alternative to University of Wisconsin solution, Celsior and histidine-tryptophan-ketoglutarate solution?

AIM: To evaluate the potential of Polysol, a newly developed preservation solution, in cold storage of small bowel grafts, compared with the current standards, University of Wisconsin solution (UW), Celsior and histidine-tryptophan-ketoglutarate solution (HTK). METHODS: Male Wistar rats were used as donors. Small bowels were retrieved, flushed and then stored in the respective 4 solutions for 18 h at 4℃. Functional integrity of the grafts was evaluated by isolated reperfusion with oxygenated Krebs-Henseleit buffer at 37℃ for 30 min in all 4 groups. RESULTS: Polysol preservation exhibited the highest tissue ATP concentration and the lowest release of LDH. Malondialdehyde, an index for tissue lipid peroxidation, was also the lowest in Polysol. Tissue oxygen consumption was significantly higher in Polysol than in the others. Of interest, UW-storage promoted 10-fold higher apoptosis than in the others. Moreover, electron microscopy revealed that the mucosal villi/micro-villi formation and the cell organelles, including mitochondria, were both significantly better preserved in Polysol, while deleterious alterations were apparent in the others, most notably in UW. Although Celsior and HTK exhibited the better trend of results than UW in some parameters, but could not reach the over-all superiority to UW.CONCLUSION: Cold storage using Polysol resulted in significantly better integrity and function of small bowel grafts than UW. Hence, Polysol may be a novel alternative for the small bowel preservation.

Effect of CXCR3/HO-1 genes modified bone marrow mesenchymal stem cells on small bowel transplant rejection

AIM To investigate whether bone marrow mesenchymal stem cells (BMMSCs) modified with the HO-1 and CXCR3 genes can augment the inhibitory effect of BMMSCs on small bowel transplant rejection. METHODS Lewis rat BMMSCs were cultured in vitro. Third-passage BMMSCs were transduced with the CXCR3 / HO-1 genes or the HO-1 gene alone. The rats were divided into six groups and rats in the experimental group were pretreated with BMMSCs 7 d prior to small bowel transplant. Six time points (instant, 1 d, 3 d, 7 d, 10 d, and 14 d) (n = 6) were chosen for each group. Hematoxylin-eosin staining was used to observe pathologic rejection, while immunohistochemistry and Western blot were used to detect protein expression. Flow cytometry was used to detect T lymphocytes and enzyme linked immunosorbent assay was used to detect cytokines. RESULTS The median survival time of BMMSCs from the CXCR3/HO-1 modified group (53 d) was significantly longer than that of the HO-1 modified BMMSCs group (39 d), the BMMSCs group (26 d), and the NS group (control group) (16 d) (P < 0.05). Compared with BMMSCs from the HO-1 modified BMMSCs, BMMSCs, and NS groups, rejection of the small bowel in the CXCR3 / HO-1 modified group was significantly reduced, while the weight of transplant recipients was also significantly decreased (P < 0.05). Furthermore, IL-2, IL-6, IL-17, IFN-gamma, and TNF-alpha levels were significantly decreased and the levels of IL-10 and TGF-beta were significantly increased (P < 0.05). CONCLUSION BMMSCs modified with the CXCR3 and HO-1 genes can abrogate the rejection of transplanted small bowel more effectively and significantly increase the survival time of rats that receive a small bowel transplant.

Immunological protection of small bowel by simultaneously transplanted liver graft in pigs

BACKGROUND: A simultaneously transplanted liver shields a bowel graft from immunologic attack in small animals, while the possible immuno-tolerance induced by the liver in liver and small bowel transplantation (LSBT) is uncertain in large animal models. To investigate the clinically suspected beneficial effect of the liver on small bowel allograft, we developed a new model of composite LSBT in the pig. METHODS: Seventy outbred long-white pigs were randomized into four groups. LSBT without immunosuppressive treatment (n=10, group A); LSBT with routine immunosuppressive treatment (n=10, group B); LSBT with a lower dose of immunosuppressive treatment (n=10, group C); and small bowel segment allotransplantation without immunosuppressive treatment (n=10, group D). RESULTS: There was no remarkable difference in survival time between groups A and D (10.33 vs. 12.89 days, P>0.05), but the initial time of acute rejection of the intestinal graft in group A was clearly delayed when compared to group D (8.22 vs. 4.33 days, P<0.05), and the rejection scores in group A were remarkably lower than those in group D at each postoperative time point (0 vs. 0.44 on day 3, P<0.05; 0.22 vs. 1.78 on day 5, P<0.05; 1.11 vs. 2.56 on day 7, P<0.05). There were evident differences in postoperative survival time, initial time of acute rejection and postoperative rejection scores between groups A, B and C. Postoperative survival time (30.00 vs. 28.13 days, P>0.05), initial acute rejection time (25.40 vs. 22.13 days, P>0.05) or rejection score did not differ between groups B and C within one postoperative month. CONCLUSIONS: Compared to isolated segment small bowel allotransplantation, the intestinal graft in LSBT (group A) had a delayed initial time of acute rejection and a lower postoperative acute rejection score, and a lower dose of immunosuppressive treatment led to persistent graft immuno-tolerance in LSBT. Thus the simultaneously transplanted liver graft may reduce the risk of intestinal rejection and protect the bowel graft from severe acute rejection.

Sirolimus-related pulmonary toxicity mimicking 'asthma like' symptoms

Sirolimus is an immunosuppressant with expanding use in pediatric organ transplantation, dermatology and rheumatology. We report two cases of children who developed asthma like symptoms and were diagnosed with interstitial lung disease, which responded to discontinuation of sirolimus. Pediatricians should be aware about the pulmonary side effects of sirolimus.