缺血预适应对大鼠移植小肠的早期保护作用

目的　研究缺血预适应 (IPC)对大鼠移植小肠上皮细胞和细胞外基质的早期保护作用。方法　SD大鼠随机分为正常对照组 (假手术组 ,S组 ,n =6 ) ,小肠移植组 (SBT组 ,n =12 )和缺血预适应加小肠移植组 (ISBT ,n =12 )。建立大鼠异位节段小肠移植模型。移植肠血管重建成功之后 ,再灌注 1h各组取材。免疫组化定量检测层粘连蛋白 (lami nin ,LN)表达。原位末端标记检测移植小肠上皮细胞凋亡。透射电子显微镜观察各组小肠上皮基底膜结构变化。结果　S组、SBT组、ISBT组LN表达分别为 39.5 2± 2 .6 0 ,13.5 3± 0 .4 4 ,2 5 .4 0± 1.79,SBT组明显低于S组 (P <0 .0 5 ) ,而ISBT组明显高于SBT组 (P <0 .0 5 )。S组、SBT组、ISBT组上皮细胞凋亡指数 (AI)分别为 2 .2± 0 .83,30 .8± 3.2 ,13.2± 2 .86 ,SBT组明显高于S组 (P <0 .0 5 ) ,ISBT组明显低于SBT组 (P <0 .0 5 )。透射电镜观察显示S组小肠上皮基底膜呈线性连续完整的结构 ,而SBT组基底膜分解断裂、甚至消失 ,ISBT组上皮基底膜破坏程度比SBT组为轻。结论　IPC对大鼠移植小肠上皮细胞和细胞外基质均有早期保护作用。IPC抑制细胞凋亡可能是其保护移植小肠上皮细胞的机制之一

Early protective effect of ischemic preconditioning on small intestinal graft in rats

Objective To investigate the early protective effect of ischemic preconditioning on small intestinal graft in rats. Methods SD rats were randomly assigned to the following study groups: sham operation group (S group, n=6), small bowel transplantation group (SBT group, n=12), and ischemic preconditioning plus small bowel transplantation group (ISBT group, n=12). Heterotopic SBT model was established. When the graft was revascularized successfully and reperfused for 1h, samples were obtained from the different groups. Laminin was analyzed with immunohistochemical staining. Quantitative analysis of laminin positive signals was performed using image acquiring analysis system. Apoptotic epithelia of small intestinal graft were detected by the TdT-mediated dUTP nick end labeling method. The morphological change of epithelial basement membrane was observed by transmission electron microscopy. Results The mean optical density value of laminin positive signals were 39.52±2.60, 13.53±0.44, and 25.40±1.79, respectively, in S, SBT and ISBT groups. The average optical density value of laminin positive products in SBT group was sharply lower than that in S group(P< 0.05). However, the mean optical density value of laminin positive products in ISBT group was significantly higher than that in SBT group(P< 0.05). The apoptotic index (AI) in S, SBT and ISBT groups were 2.2±0.83, 30.8±3.2, and 13.2±2.86, respectively. The AI in SBT group was significantly higher than that in S group (P< 0.05) . The AI in ISBT group was sharply lower than that in SBT group (P< 0.05). Transmission electron microscopy revealed that the epithelial basement membrane in S group stayed normal, but in SBT group it became disrupted, collapsed, and even disappeared. The lesion of the epithelial basement membrane in ISBT group was milder than that in SBT group. Conclusion Ischemic preconditioning has an early protective effect on epithelial cells and extracellur matrix of small intestinal graft. Inhibition of epithelial cell apoptosis may be one of mechanisms of ischemic preconditioning.