增强MRI对胰腺导管腺癌组织渗透性评估价值的实验研究

Experimental study on the value of enhanced MRI in evaluating the permeability of pancreatic ductal adenocarcinoma

目的探讨增强MRI对胰腺导管腺癌(PDAC)小鼠模型组织渗透性的评估价值。方法实验动物为雌性C57BL/6小鼠27只,采用随机数字法将小鼠分为3组,每组9只。将小鼠PDAC细胞(Panc02)与胚胎成纤维细胞(NIH/3T3)以2∶1和1∶1的比例种植于小鼠皮下,构建不同组织渗透性的PDAC小鼠皮下瘤模型,分别为低成纤维细胞组和高成纤维细胞组,单纯Panc02细胞种植模型为对照组。利用组织染色对各组肿瘤α-平滑肌肌动蛋白(α-SMA)阳性表达率、成纤维细胞活化蛋白(FAP)阳性表达率、胶原纤维覆盖率、血管数量以及组织血管长径/短径进行量化评估,利用伊文思蓝(EB)染色的组织切面平均光密度值(AOD)量化组织渗透效率。对小鼠行增强MRI,获得20 min强化程度和20 min强化率。采用单因素方差分析比较各组小鼠肿瘤组织学指标和MRI增强参数的总体差异,指标间相关性均采用Pearson相关分析。以20 min强化率为因变量,α-SMA阳性表达率、胶原纤维覆盖率和血管长径/短径3种组织学指标为自变量,进行多元线性逐步回归分析。结果3组小鼠肿瘤组织AOD值、α-SMA阳性表达率、FAP阳性表达率、胶原纤维覆盖率、血管长径/短径、20 min强化程度和20 min强化率的总体差异均具有统计学意义(P均<0.001),血管数量总体差异无统计学意义(P=0.650)。小鼠PDAC组织的AOD值与α-SMA阳性表达率、胶原纤维覆盖率、血管长径/短径呈负相关(r=-0.888,P=0.001;r=-0.813,P=0.008;r=-0.915,P<0.001)。20 min强化程度与AOD值呈正相关(r=0.954,P<0.001),20 min强化率与α-SMA阳性表达率、胶原纤维覆盖率、血管长径/短径均呈负相关(r=-0.901,P<0.001;r=-0.837,P=0.005;r=-0.880,P=0.002)。多元线性逐步回归分析结果显示,α-SMA阳性表达率是肿瘤20 min强化率的重要影响因素(R2=0.813,P=0.001)。结论成纤维细胞的种植比例提高可显著降低肿瘤组织渗透效率。增强MRI 20 min肿瘤强化程度与组织渗透效率呈正相关。

Objective To investigate the value of enhanced MRI in evaluating the tissue permeability of pancreatic ductal adenocarcinoma(PDAC)animal model.Methods The experimental animals were 27 female C57BL/6 mice.The mice were divided into 3 groups with 9 mice in each group by random number method.Murine pancreatic adenocarcinoma(Panc02)and embryonic fibroblasts(NIH/3T3)were implanted subcutaneously at the ratio of 2∶1 and 1∶1 to establish PDAC models with different tissue permeability,which were low fibroblast group and high fibroblast group,respectively,and simple Panc02 implantation model was control group.The positive expression rate ofα-smooth muscle actin(α-SMA),the positive expression rate of fibroblast activating protein(FAP),the coverage rate of collagen fibers,number of blood vessels and the long/short diameter of tissue vessels were quantitatively evaluated by tissue staining,and the tissue permeation efficiency was quantified by the average optical density(AOD)of tissue sections stained by Evans blue(EB).Enhanced MRI was performed on mice,and the enhancement degree and the enhancement rate of 20 min were obtained.One-way ANOVA was used to compare the overall differences of tumor histological indexes and MRI enhancement parameters in each group,and the correlation between the indexes was analyzed by Pearson correlation analysis.Multiple linear stepwise regression analysis was conducted with 20 min enhancement rate as dependent variable,whileα-SMA positive expression rate,collagen fiber coverage rate and vascular long/short diameter as independent variables.Results There were significant differences in AOD value,α-SMA positive expression rate,FAP positive expression rate,collagen fiber coverage rate,vascular long/short diameter,20 min enhancement degree and 20 min enhancement rate among the three groups(P<0.001),but there was no significant difference in the number of blood vessels(P=0.650).The AOD value was negatively correlated with the positive expression rate ofα-SMA,the coverage rate of collagen fibers and the long/short diameter of blood vessels in PDAC model,respectively(r=-0.888,P=0.001;r=-0.813,P=0.008;r=-0.915,P<0.001).The 20 min enhancement degree was positively correlated with AOD value(r=0.954,P<0.001).The positive expression rate ofα-SMA,collagen fiber coverage and vascular long/short diameter were negatively correlated with 20 min enhancement rate(r=-0.901,P<0.001;r=-0.837,P=0.005;r=-0.880,P=0.002).The results of multiple linear stepwise regression analysis showed that the positive expression rate ofα-SMA was an important influencing factor for the 20 min enhancement rate(R2=0.813,P=0.001).Conclusions The increase of fibroblast implantation ratio significantly decreased the permeation efficiency of tumor tissue.The positive expression rate ofα-SMA,the coverage rate of collagen fibers and the long/short diameter of blood vessels were negatively correlated with the permeation efficiency of tumor tissue.The 20 min enhancement degree was positively correlated with tissue permeation efficiency.