可取出式食管支架预防烧伤后瘢痕狭窄的实验研究

Prevention of esophageal stricture with retrievable esophageal stent after corrosive esophageal burns in dogs

目的探讨可取出式食管支架(retrievable esophageal stent,RES)置入烧伤家犬食管内4个月后能否顺利取出及对食管烧伤后瘢痕狭窄的预防作用。方法24只家犬根据随机数字表法分为对照组(未烧伤)、烧伤组(烧伤后不给予任何治疗)及治疗组(伤后2周置入RES,4个月后拔管),治疗组又根据拔管后观察时间分为治疗Ⅰ组(拔管后立即处死)及治疗Ⅱ组(拔管后2个月处死)。测定离体食管的狭窄指数,观察其显微及超微结构,比色法检测食管组织羟脯氨酸含量,分别采用原位杂交及ELISA法测定食管组织Ⅰ、Ⅲ型胶原mRNA表达及蛋白水平,检测食管顺应性及生物力学特性,RT-PCR及Western blot分别测定TGF-β1、Smad3、Smad7的mRNA表达及蛋白水平。结果RES置入4个月后能顺利取出。烧伤组伤后3周发生吞咽困难,仅1只家犬存活至实验完毕,治疗Ⅰ、Ⅱ组实验中无死亡,RES置入后进食无异常,处死前体质量与实验前无显著性差异。与烧伤组相比,治疗Ⅰ、Ⅱ组食管狭窄指数、组织羟脯氨酸水平和Ⅰ、Ⅲ型胶原mRNA表达及蛋白水平均显著减低(P<0.05);食管顺应性及弹性明显增加,组织学检查胶原纤维较细,排列较规则;食管组织TGF-β1、Smad3mRNA表达及蛋白水平下调,而Smad7升高(P<0.01)。结论RES置入烧伤家犬食管内4个月能顺利取出,取法简便。RES能有效预防食管烧伤后瘢痕狭窄形成。食管组织TGF-β1、Smad3增加及Smad7降低可能是RES预防烧伤瘢痕狭窄的分子机制之一。

To probe whether retrievable esophageal 4 months after placement and prevent forming esophageal stricture stent （RES） in dogs with can be removed successfully corrosive esophageal Methods Twenty-four dogs were randomly divided into control （without esophageal burns）, burn （ treatment for esophageal burns） and treatment group burns. without （ RES was placed at 2 weeks after esophageal burns and removed 4 months later）. The treatment group was further divided into RES Ⅰ （ dogs being killed immediately after RES withdrawal） and RES Ⅱ （dogs being killed 2 months after RES removal）. Stricture index was measured and microscopic and ultrastructural features were observed in the harvested esophagus. Hydroxyproline quantities by colorimetry, type Ⅰ and Ⅲ collagen mRNA expression by in situ hybridization and their protein levels by ELISA were detected in esophageal tissues. The esophageal compliance and biomechanics were also examined in dogs. TGF-β1, Smad3, Smad7 mRNA expression by RT-PCR and their protein levels by Western blotting were investigated. Results One dog died of aspiration less than 24 h after esophageal burns in the burn group, and others developed progressive dysphagia since 3 weeks after injury, only one dog survived. No animal deaths in the groups RES Ⅰ and Ⅱ through RES replacement and no significant changes the experiment. All dogs could intake regular diet following was in their weight before and after the experiment. with the burn group, stricture index, type Ⅰ and Ⅲ collagen mRNA and protein levels, and quantities decreased significantly in the groups RES Ⅰ and Ⅱ （P 〈 0. 05 ）, while the esophageal In comparison hydroxyproline compliance and elasticity among the biomechanics improved dramatically; Histopathological study revealed that collagen diameter was thinner and its orientation tended toward regular and parallel pattern; TGF-β1 and Smad3 mRNA and protein levels increased but Smad7 decreased significantly in esophageal tissues in the groups RES Ⅰ and Ⅱ （P 〈 0. 01 ）. Conclusion RES can be extracted successfully and conveniently 4 months after placement and prevent developing esophageal stenosis in dogs with corrosive esophageal burns. The changes of TGF-β1, Smad3 and Smad7 mRNA and protein levels might relate to the preventive role of RES.