第一临床医学院知识库

目的： 合成Ⅰ型胶原蛋白的MR分子探针，并应于用小鼠的肝脏MR成像，以期实现肝纤维化的定性诊断。材料与方法：使用固相法、以各种氨基酸为原料合成Ⅰ型胶原蛋白结合多肽（LRELHLNNNG，TICTP），并利用有机小分子全合成法使用前体轮环藤宁合成交联剂DOTA，随后制备TICTP-DOTA复合物，最后螯合钆离子得到多肽-DOTA-Gd复合物TICTP1，并使用质谱分析及NMR波谱分析确认化学结构。选取昆明小鼠80只，随机分为两组，实验组60只，使用四氯化碳分次腹腔注射法制作肝纤维化小鼠模型，同期每周造模后第一天随机选取两只小鼠尾静脉注射TICTP1后进行MR肝脏T1预扫描，通过观察肝脏组织信号变化，发现造模6周后的小鼠在注射后TICTP1明显升高，对应病理期为F3期（METAVIR标准）；对照组腹腔注射相同剂量PBS溶液。分别随机选取注射6周的实验组小鼠及对照组各10只，实验组及对照组分别随机分为两组，每组5只，分别注射TICTP1（0.5μmol/ml，1.5ml/100g体重）及相同浓度剂量的马根维显，行MR肝脏 T1 5min、 60min、120 min、180 min扫描，动态观察肝脏信号变化曲线，及肝脏组织与同层面竖脊肌的信号比值。同期取小鼠肝脏组织行病检。使用SPSS 16.0行统计学分析。

结果：1.成功合成多肽-DOTA-Gd复合物TICTP1，质谱分析结果与预期相符。2.成功构建不同病理分期的小鼠肝纤维化病理模型。3.根据预实验结果取F3期小鼠进行定性实验，可观察到注射分子探针TICTP1的实验组小鼠肝脏T1信号明显升高，F3期肝纤维化组注射分子探针TICTP1 180min后，小鼠肝脏的MR信号改变与注射马根维显组、正常对照组之间差异均有统计学意义（p<0.05），ROC曲线下面积、敏感度、特异度均为1。而对照组及注射马根维显的实验组小鼠肝脏T1信号未见明显变化（p＞0.05）。结论：1.成功合成多肽-DOTA-Gd复合物TICTP1；2. TICTP1可作为小鼠肝纤维化特异性显像的MR分子探针。

Objective: Synthesize MR probes of type I collagen and use for liver MR imaging in mice to achieve qualitative diagnosis of liver fibrosis.Method:. Synthesis of type I collagen-binding peptides (LRELHLNNNG, TICTP) from various amino acids using the solid phase method and the synthesis of the crosslinker DOTA using the precursor epoxide vinegar using the organic small molecule total synthesis method, followed by the preparation of TICTP-DOTA The complex finally chelates cesium ions to obtain the peptide-DOTA-Gd complex TICTP1, and the chemical structure is confirmed using mass spectrometry analysis and NMR spectroscopy. Eighty Kunming mice were randomly divided into two groups, 60 in the experimental group, and mice models of hepatic fibrosis were produced by intraperitoneal injection of carbon tetrachloride. Two mice were randomly selected on the first day after the weekly model establishment. After pre-scanning of MR liver T1 by tail vein injection of TICTP1, the liver tissue signal changes were observed. It was found that TICTP1 was significantly elevated in mice after 6 weeks of modeling, and the corresponding pathological phase was F3 (METAVIR standard); Inject the same dose of PBS solution. Ten mice in the experimental group and 10 in the control group were randomly selected for each injection for 6 weeks. The experimental group and the control group were randomly divided into two groups, 5 in each group. They were injected with TICTP1 (0.5 μmol/ml, 1.5 ml/100 g weight). At the same dose of Magnevist, MR liver T1 was scanned at 5 min, 60 min, 120 min, and 180 min to dynamically observe the changes of liver signal and the signal ratio of liver tissue to the erector spinae of the same plane. At the same time, mouse liver tissue was taken for examination. Statistical analysis using SPSS 16.0.

Result: 1. The peptide-DOTA-Gd complex TICTP1 was successfully synthesized and the results of mass spectrometry analysis were in agreement with expectations. 2. Successful construction of pathological models of liver fibrosis in mice with different pathological stages. 3. According to the results of preliminary experiments, F3 mice were tested qualitatively, and the T1 signal in the liver of the mice injected with the molecular probe TICTP1 was significantly increased. The mice liver was injected 180 minutes after the injection of the molecular probe TICTP1 in the F3 liver fibrosis group. The differences of MR signal changes and injections of Magnevistin group and normal control group were statistically significant (p<0.05). The area under ROC curve, sensitivity, and specificity were both 1. However, there was no significant change in liver T1 signal in the control group and the experimental group injected with Magnevist (p>0.05).Conclusion: 1. Successful synthesis of polypeptide-DOTA-Gd complex TICTP1. 2. TICTP1 can be used as a MR molecular probe for mouse liver fibrosis specific imaging.