Small-bowel transplantation in the rat with a nonsuture cuff technique. Technical and immunological considerations

Protective effects of mannitol against small bowel ischemia and reperfusion injury after transplantation in rats

AIM: To investigate the effect of mannitol on small bowel ischemia and reperfusion (I/R) injury after transplantation and its possible mechanism.

METHODS: Rat models of small bowel I/R injury after transplantation were established in male rats. All the rats were randomly divided into sham operation group, I/R group and mannitol-treated group. After 0.5, 1 and 1.5 hours of I/R, intestinal tissues were collected for histopathological examination. The content of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) in the intestinal tissues.

RESULTS: The height and thickness of intestinal intestinal villi were significantly lower in I/R group than those in sham operation group (P < 0.01) and mannitol-treated group (P < 0.05). At different time points, the content of MDA was markedly higher in I/R group (16.24 ± 4.56, 18.50 ± 2.89, 19.42 ± 2.21) than that in sham operation group (10.26 ± 1.72, P < 0.01) and mannitol-treated group (11.24 ± 1.51, 14.03 ± 3.12, 16.06 ± 3.62; P < 0.05), but the activity of SOD was notably higher (398.36 ±1 8.81, 363.16 ± 16.29, 325.66 ±1 4.58 vs 447.97 ± 16.94; 422.30 ±1 7.41, 385.09 ± 19.11, 346.15 ± 14.10; P < 0.01 or P < 0.05).

CONCLUSION: Mannitol has protective effect against small bowel I/R injury after transplantation in rats by eliminating free radicals.

Immuno-protective effect of liver on small bowel in combined transplantation of liver and small bowel

AIM: To develop a new combined transplan-tation model of liver and small bowel in rats, and to investigate the protective effect of trans-planted liver on transplanted small bowel.

METHODS: Closed colony Sprague Dawley rats and inbred Wistar rats were included in this study. Five groups were designed: isogene small bowel transplant group (A), isogene liver transplant group (B), xenogene small bowel transplant group (C), xenogene liver transplant group (D), combined transplant of liver and small bowel group (E). Only Wistar rats were used in group A and B, while SD and Wistar rats were used as donors and recipients respectively in group C, D and E. During the combined transplantation of liver and small bowel (CTLS) for the donors, inferior vena cava in chest was cut to construct a muff in the lateral wall of portal vein and cuff was placed. During the operation for the recipients, portal veins of the donors and recipients were connected using cuff technique, and re-arterialization was completed by anastomosing the superior mesenteric artery of graft with the right kidney artery of the recipients. Randomly selected 4 rats from each group were sacrificed on postoperative days (POD) 5, 7 and 14, and grafts were sampled. The rejection of graft was investigated through histopathological analysis, and the apoptosis of the cells of graft were evaluated by TUNEL.

RESULTS: The survival rate of CTLS was 73.3% (22/30). The pathological changes of ischemia and reperfusion injury were observed in group A and B, and the numbers of apoptotic cells in the grafts were decreased with the prolonging of time. However, acute rejection after transplantation appeared in group C and D, and there were more apoptotic cells in the grafts. Mild, moderate and severe acute rejection occurred on POD 5, 7 and 14, respectively in group C, while only mild or severe acute rejection appeared in group E. Furthermore, the number of apoptotic cells in the grafts of group E was markedly decreased on POD 14 in comparison with that of group C (16.9 ± 4.3 vs 20.5 ± 6.3, P < 0.05). The degrees of acute rejection after transplantation and cell apoptosis of the grafts were not significantly different between group D and E.

CONCLUSION: The technique used in this study is feasible for establishment of CTLS model, and the transplanted liver can protect the transplanted intestinal graft from rejection in CTLS.